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Hydrocarbon Accumulation Conditions and Exploration Directions of the Devonian in the Central Part of Western Sichuan Depression LI Shuangjian, ZHANG Lei, MA Jianfei, WU Qingjie, MENG Xianwu, DUAN Nan, SHI Lei Xinjiang Petroleum Geology    2026, 47 (4): 379-392.   DOI: 10.7657/XJPG20260401 Abstract （56）   HTML （13）    PDF（pc） （23067KB）（34）       Knowledge map    Save Influenced by the expansion of the Paleo-Tethys Ocean, the Devonian system along the western margin of the Yangtze Block presents a continuous sedimentary succession, with thickness up to several kilometers, providing favorable petroleum geological conditions. Due to complex surface structures and large burial depth of the Devonian in the Longmenshan piedmont zone of the Western Sichuan depression, this area has been insufficiently explored and studied. Moreover, there is limited research on stratigraphic distribution, reservoir development patterns, and hydrocarbon accumulation and preservation conditions of the Devonian in the deeply buried zones in the basin. Based on high-precision, contiguous 3D seismic data, this study identifies and confirms the presence of Middle-Upper Devonian high-energy facies zones. By integrating drilling and outcrop data, the fundamental hydrocarbon accumulation conditions of the Devonian in the central part of the Western Sichuan Depression are clarified, and future exploration directions are proposed. The results show that the strata in the Middle Devonian-Carboniferous in the central part of the Western Sichuan depression have a residual thickness ranging from 0 to 450 m, gradually decreasing from west to east, with a distribution area of up to 6,500 km2. The Middle-Upper Devonian is primarily an open platform to restricted platform depositional system, where high-quality reservoirs are mainly intraplatform facies and contain dissolution pores/vugs, jointly controlled by high-energy facies zones, fractures and early-stage dissolution. These high-quality reservoirs exhibit distinct medium-strong amplitude, discontinuous reflection features on seismic sections, and distribute as NE-SW-trending strips, covering an area of approximately 2,000 km2. Structural-lithologic traps in the Middle-Upper Devonian across the Western Sichuan depression, formed during the Indosinian period, show a good match with the peak hydrocarbon generation period of the Cambrian main source rocks. The overlying Triassic gypsum-salt rocks serve as a regional seal, ensuring excellent preservation conditions. Individual reservoirs can reach 100 m in thickness. These characteristics imply potential for forming large-to-medium, high-abundance gas fields. It is concluded that the Middle-Upper Devonian can be taken as a favorable target for deep-to-ultradeep marine exploration in the Sichuan Basin. Table and Figures | Reference | Related Articles | Metrics

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Offshore Petroleum Exploration History and Enlightenment in Beibu Gulf Basin LI Fanyi, ZHANG Houhe, LI Chunrong, ZHANG Wenzhao, HAO Jing, XU Qingmei, YAN Han Xinjiang Petroleum Geology    2021, 42 (3): 337-345.   DOI: 10.7657/XJPG20210310 Abstract （1485）   HTML （19）    PDF（pc） （1700KB）（2509）       Knowledge map    Save The paper analyzes the historical data of drilling, seismic survey, reserves and production, summarizes the offshore exploration achievements and targets and petroleum geology theory, then divides the offshore exploration process in the Beibu Gulf basin into three stages: (1) Early exploration stage (1960-1995). Drilling results proved that there are good source rocks and source-reservoir-cap assemblages in the Beibu Gulf basin, the basic structural characteristics was understood, and the secondary tectonic units were divided. Early exploration results laid a good foundation for further oil and gas exploration during 1980s when there was a high tide of foreign cooperation. (2) Breakthrough to the Weixinan sag and progressive exploration stage (1995-2010). The discovery and successful evaluation of a number of oilfields represented by Weizhou 12-1 firstly contributed to the cumulative proven geological reserves of oil in the Beibu Gulf basin exceeding 100 million tons. Facing the condition that the Weixinan sag is full of oil but the average size of the oilfields in the sag is relatively small, a progressive exploration strategy was put forward, which broke the bottleneck and realized the upgrading and increase of reserves. (3) Breakthrough to the Wushi sag and exploration into new areas (since 2010). The discovery and successful evaluation of a number of oilfields represented by Wushi 17-2 proved that the Wushi sag is another hydrocarbon-rich sag that has been confirmed by drilling data following the breakthrough of the Weixinan sag. This opened a new prospect in the Beibu Gulf basin. Meanwhile, the exploration to new targets such as buried-hill reservoirs led to the identification of a number of pre-Paleogene carbonate reservoirs which are potential contribution to sustainable development. Table and Figures | Reference | Related Articles | Metrics

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Karst Paleogeomorphology and Development Model of Karst Fracture-Cave Bodies of Ordovician in Halahatang Sag ZHANG Qingyu1,2, LIANG Bin2, QIN Fengrui2, CHEN Lixin3, DAN Yong2, LI Jingrui2 null    2016, 37 (6): 1-1.   DOI: 10.7657/XJPG20160606 Abstract （229）      PDF（pc） （4308KB）（1456）       Knowledge map    Save In view of different geological features of buried-hill weathering crust areas in the north and buried karst area in the south of Halahatang area in the northern Tarim basin, the Ordovician paleolandform and ancient drainage systems are restored using impression method and a combination method of paleostructure and residual impression. The karst fracture-cave body development characteristics and its formation mechanism are studied under 4 different paleo-landform environments, and 4 karst fracture-cave body development patterns are established such as buried-hill weathering crust zone, upper karst slope, lower karst slope and karst basin. The buried-hill weathering crust zone is dominated by surface-karst fracture-cave system; large fracture-cave bodies of Yijianfang formation-Yingshan formation and underground river channel systems mainly occur in the upper-karst slope; 2 sets of large fracture-cave bodies namely Liang-1-Liang-2 member and Yijianfang formation-Yingshan formation are developed on the lower karst slope; and karst fracture-cave bodies are distributed along faults in the karst basin Related Articles | Metrics

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Spontaneous Imbibition of Tight Oil Reservoirs Based on NMR Technology JU Mingshuang, WANG Xiuyu, YU Wenshuai, YANG Shenglai, YE Wenzhuo, ZHANG Tianqing null    2019, 40 (3): 1-1.   DOI: 10.7657/XJPG20190312 Abstract （310）      PDF（pc） （300KB）（861）       Knowledge map    Save China’s tight oil resources are rich in reserves and have huge economic value, but it is difficult to develop due to the features of low permeability and low porosity of tight oil reservoirs. The spontaneous imbibition principle based on capillary pressure becomes an effective production mechanism for such reservoirs. Combining with nuclear magnetic resonance(NMR) experiments, the paper clarifies the spontaneous imbibition flow law of fluids in tight core, studies the influences of core permeability, core length and one-way imbibition on the recovery percent of spontaneous imbibition based on T2 spectrum and imaging maps obtained from the nuclear magnetic experiment, and observes 2D fluid flowing and distribution in the core. The comparison result shows that the recovery percent of spontaneous imbibition obtained from T2 spectrum is consistent with that obtained from the mass method, which verifies the applicability using NMR experiments to study tight reservoir spontaneous imbibition and provides a reliable theoretical basis for tight oil development Related Articles | Metrics

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Analysis of Seismic Imaging Characteristics of Volcanic Rocks and Underlying Strata Based on Physical Models: A Case Study of Chaganhua Subsag, Southern Songliao Basin MIAO He, LI Ning, XING Tingdong, TIAN Jun Xinjiang Petroleum Geology    2026, 47 (4): 515-524.   DOI: 10.7657/XJPG20260416 Abstract （35）   HTML （4）    PDF（pc） （11013KB）（14）       Knowledge map    Save In the southern Songliao Basin, deep strata experienced intense volcanic activity during faulting period. Volcanic rocks act as the critical hydrocarbon reservoir rocks, but they interfere the seismic imaging of underlying strata. It is very important to study the impact of volcanic rocks on seismic imaging of underlying strata. Based on the typical characteristics and elastic parameters of the volcanic rocks in two eruption cycles and the overlying and underlying rocks in the Chaganhua subsag of the Changling fault depression, physical models were built by scaling down, and seismic acquisition and image processing were performed. On this basis, the impacts of the volcanic rocks on the seismic imaging of the underlying strata were analyzed. The results show that equivalent velocity and density models for volcanic rock formations can be constructed using mixed materials with mica powder and epoxy resin as cementing agents to simulate volcanic rock with high wave impedance and high hardness, together with different proportions of organic crystals to simulate different facies zones. These physical models yield the errors of P-wave velocity less than 2%. It is found that the volcanic rocks of Lower Cretaceous Yingcheng formation have great impacts on the well-seismic calibration of the underlying strata, the thickness of the volcanic rocks and the thickness of the underlying clastic rocks jointly affect the well-seismic calibration of the volcanic rocks of the Lower Cretaceous Huoshiling formation, and the seismic imaging-derived velocity in the volcanic rock area is smaller than the actual velocity of the strata. Based on the research results from the physical models, and considering the data of existing wells and previously acquired insights on the thickness and distribution of the volcanic rocks and clastic rocks, grid tomographic velocity modeling was conducted to iteratively optimize the velocity model, improving the compatibility between actual seismic data and synthetic seismogram. This study provides reference for seismic imaging in volcanic rock areas in other regions around the world. Table and Figures | Reference | Related Articles | Metrics

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Structural Pivot Zone and Its Oil-Gas Accumulation Conditions in Tarim Basin WANG Wei-guang, LV Xiu-xiang, YU Lian, CHENG Ke-nan Xinjiang Petroleum Geology    2011, 32 (4): 333-337.   Abstract （275）      PDF（pc） （390KB）（875）       Knowledge map    Save Tarim basin has undergone multi-stage differential elevating-subsiding motion and periphery orogeny, and formed a series of structural pivot zones. Their formation is closely related to the formation and evolution of uplifts and slopes. According to the differences of forming characteristics and developing positions, the pivot zone can be divided into three types: uplift-tilted type, slope-reversed type and uplift-slope compound type. The superior hydrocarbon accumulation conditions are generally found in these types of pivot zones in adjacent source area, carbonate rock karst, weathering crust, reef-bank and karst type reservoirs, and traps are dominated by buried hill and structural-lithologic traps. With respect to sag or source areas, the pivot zones are normally in higher locations, being the pointing area of hydrocarbon migration; while with respect to the uplift top, they are in lower ones, favorable for hydrocarbon preservation. Therefore, no matter for hydrocarbon capture or preservation, the pivot zones always locate in favorable positions. In addition, the hydrocarbon distribution in pivot zones is obviously characterized by complex hydrocarbon accumulation. Reference | Related Articles | Metrics

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Influences of Gelled Acid on Mechanical Properties of the Ordovician Carbonate Rocks in Block Shunbei, Tahe Oilfield LI Chunyue1, WANG Yang1, DENG Peng1,2, GUO Yintong2, XU Feng3, ZHOU Jun2 null    2018, 39 (6): 1-1.   DOI: 10.7657/XJPG20180609 Abstract （245）      PDF（pc） （2211KB）（443）       Knowledge map    Save From the perspective of macroscopic and microscopic points, the paper studies the influences of gelled acid used during fracturing on the mechanical properties of the Ordovician carbonate rocks in the Block Shunbei of Tahe oilfield, which could provide basis for efficient development of the carbonate reservoirs in the target blocks. The experiments were carried out to test the influences on microscopic structures and its mechanical properties of carbonate rock samples after treatment by gelled acid and the results showed that the mineral components of the Ordovician carbonate rocks in Shunbei area are characterized by high contents of carbonate minerals, low content of quartz and a few impurities; after the static acid-rock reaction, the intercrystal distance of minerals significantly increases and the calcite content reduces from 93% to 88%, indicating a high-brittleness fracturable reservoir; the static acid-rock reactions in different acid fluids and the corresponding uniaxial compression tests show that the optimal reaction time is 30 minutes, and each physical parameter and mechanics index get worse obviously; the density and P-wave velocity decrease obviously after 30 minutes of gelled acid treatment for the rock samples and the tensile and shear strengths significantly drop; the gelled acid as a reaction acid fluid can result in acid etching to the macrostructures and some damages to micropores of the carbonate rock samples. Therefore, the gelled acid is of great significance for carbonate reservoir fracturing and fracture propagation Related Articles | Metrics

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Patterns and Genetic Mechanisms of Spatial Differentiation of Crude Oil Physical Properties in the Mabei Area, Junggar Basin REN Haijiao, LI Guangxing, ZHAO Yi, HE Wenjun, YU Shuang, YANG Sen, LI Na, LI Hui, ZHU Tao Xinjiang Petroleum Geology    2026, 47 (4): 393-403.   DOI: 10.7657/XJPG20260402 Abstract （43）   HTML （6）    PDF（pc） （2282KB）（13）       Knowledge map    Save The Mabei area in the Mahu sag of the Junggar Basin has yielded significant hydrocarbon discoveries in multiple strata, including the Carboniferous, Permian, and Triassic. However, physical properties of crude oil vary spatially and stratigraphically, and the genetic mechanism underlying this differentiation represents a critical geological factor constraining hydrocarbon exploration. In this study, analyses on total hydrocarbon chromatography and biomarker were systematically performed. Based on the differential distribution of crude oil physical properties, the genetic mechanism of spatial differentiation was investigated, and an oil accumulation model for the Mabei area was established. The results show that the chemical composition of crude oil is the fundamental cause of physical property variations. Differences in depositional environment and thermal maturity of source rocks give rise to variations in chemical composition. In addition, multi-stage charging, mixing, and biodegradation further complicate the physical properties of crude oil. The Triassic crude oil in the sag and slope zones features low density, low viscosity, high wax content, and a high freezing point. It has a high proportion of saturated hydrocarbons and a low content of isomeric branched alkanes, indicative of predominantly high-mature oil. This oil was sourced from the high-maturity source rocks of the Fengcheng formation in the sag, migrated upward along faults, and accumulated in shallow reservoirs. The Permian crude oil in the slope zones and the conventional crude oil in the fault zones is characterized by high density, high viscosity, low wax content, and low freezing point. These oils have low saturated hydrocarbon content but abundant isomeric branched alkanes, and are dominated by mature oil, with a minor proportion of high-mature oil. Specifically, the mature oil originated from the source rocks of the Fengcheng formation in the fault and slope zones, forming reservoirs through vertical near-source migration or in-situ accumulation. The high-mature oil, which occurs only in the fault zones, is interpreted to have been sourced from both the Fengcheng and Jiamuhe formations, with lateral migration as the primary transport mechanism. The shallow heavy oil in the fault zones, buried at depths of less than 1,500 m, has a high freezing point and was mostly subjected to biodegradation. Table and Figures | Reference | Related Articles | Metrics

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Petroleum Exploration History and Enlightenment in the Northern Songliao Basin MENG Qi’an, LI Chunbai, BAI Xuefeng, ZHANG Wenjing, XUE Tao, PENG Jianliang, TANG Zhenguo Xinjiang Petroleum Geology    2021, 42 (3): 264-271.   DOI: 10.7657/XJPG20210302 Abstract （1133）   HTML （29）    PDF（pc） （1691KB）（2182）       Knowledge map    Save According to the exploration history in the northern Songliao basin, this paper summarizes the research results in different exploration stages and analyzes how the exploration idea in each stage changed and its role to exploring new targets. The Songliao basin went through three stages of oil and gas exploration: exploration of structural oil reservoirs (1955–1985), exploration of lithological oil reservoirs (1986–2010), and exploration of both conventional and unconventional oil and gas reservoirs (since 2011). The enlightment lies in objective geological conditions and the understanding of reservoir forming laws are the foundation for exploration deployment, sustainable theoretical innovation is the guarantee to make breakthroughs to oil and gas exploration, and technological innovation of engineering is the key to keeping steady increase of oil and gas reserves. The mature exploration areas in the basin are still primary exploration targets to discover large and medium-sized oil and gas fields in the future. Table and Figures | Reference | Related Articles | Metrics

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Experimental Study on Variable Flow Resistance during Polymer Flooding in Vertically Heterogeneous Reservoirs LIU Zheyu1, LI Yiqiang1, GAO Wenbing1, XUE Xinsheng2, WANG Shanshan2, LI Xiaoxu1 null    2017, 38 (3): 1-1.   DOI: 10.7657/XJPG20170313 Abstract （240）      PDF（pc） （300KB）（399）       Knowledge map    Save Good application results of field polymer flooding test have been achieved in many oil fields, but “profile reversion” often occurs during polymer flooding process and the conventional theory of alternate polymer injection to control profile reversion is not suitable for vertically heterogeneous reservoir development. Starting with resistivity calculation of oil-water two-phase flows, this paper studies the profile reversion mechanism and its discriminant method, discusses the EOR mechanism of alternate polymer injection during general oilfield development and determines the limits of permeability contrast applicable for polymer flooding. The study result shows that the injection volume corresponding to the extreme points of fluidity in each layer is just the point where the injection profile reversion occurs during polymer flooding; when the vertically heterogeneous reservoirs are developed generally, liquid absorption amounts in low-permeability layers are not significantly improved by alternate polymer injection, whereas the processes of oil aggregation and oil bank forming can enhance oil recovery; when the permeability contrast is higher than 4 in the vertically heterogeneous reservoirs, the single-stage polymer flooding can’t get the optimal development effect, the injection profile should be modified and then polymer flooding can be carried out again to improve the oil recovery percent of reserves. Related Articles | Metrics

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Optimization of Volcanic Gas Reservoir Development Program Based on the Improved AHP-Entropy Weight Method and TOPSIS MA Xu1, YANG Shuangchun1, LI Bingfan2, PAN Yi1, MA Peimin3 null    2017, 38 (3): 1-1.   DOI: 10.7657/XJPG20170312 Abstract （149）      PDF（pc） （300KB）（387）       Knowledge map    Save How to choose the optimal program for volcanic gas reservoir development economically is an urgent problem to be solved. According to the construction principle of the indexes of volcanic gas reservoir development program optimization, 7 optimum indexes of development program are determined. By using the improved analytical hierarchy process (AHP) and combined with entropy weight method and the technique for order preference by similarity to ideal solution（TOPSIS), an improved AHP-entropy weight & TOPSIS-based model for volcanic gas reservoir development program optimization is established and its validity has been verified by a case study of optimization for 8 volcanic gas reservoir development programs in a block of Songliao basin. The results show that the approximation degrees of each program are 0.2947, 0.5041, 0.6798, 0.7675, 0.3165, 0.6407, 0.6213 and 0.2546, respectively. Based on the optimal selection principle, it is considered that the optimal solution is the program No.8. The optimization result could provide references for decision making in oilfields, which has some practical and theoretical significance. Related Articles | Metrics

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Using Discrete Element Numerical Simulation Method to Study Salt Tectonic Deformation Mechanism of Kelasu Structural Belt DUAN Yunjiang1, HUANG Shaoying1, LI Weibo2, ZHANG Huifang1, MA Xiaodan1, LIAO Feiran1 null    2017, 38 (4): 1-1.   DOI: 10.7657/XJPG20170406 Abstract （259）      PDF（pc） （300KB）（998）       Knowledge map    Save In order to research the tectonic compressional deformation and its main controlling factors of salt structures in Kelasu structural belt of Kuqa depression, the paper simulates the salt tectonic deformation process of the 3 major seismic sections of Awat, Dabei and Keshen segments by using discrete element numerical simulation method. The simulation results show that the salt bed exhibits plastic deformation under the compressional setting and has relatively strong fluidity. Post-salt, salt and pre-salt beds show some structural characteristics of overall compression and layered deformation. A series of NS trending thrust structures are developed in pre-salt beds, and fault propagating folds and detached deformation structures are developed in post-salt beds. Pre-existing fractures mainly control pre-salt tectonic deformation and stress propagation range, pre-existing salt diapirs mainly influence the tectonic uplifting range of post-salt beds; salt rock distribution and palaeohigh of basement mainly impact the tectonic deformation of post-salt beds. The study results reveal the dynamic evolution process of salt structures in Kelasu structural belt, which will benefit to improve the understandings on salt tectonic deformation mechanism and its evolution process. Related Articles | Metrics

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Structural Characteristics and Evolution in the Southern Margin of Junggar Basin ZHU Ming, WANG Xin, XIAO Lixin Xinjiang Petroleum Geology    2020, 41 (1): 9-17.   DOI: 10.7657/XJPG20200102 Abstract （1719）   HTML （53）    PDF（pc） （13286KB）（677）       Knowledge map    Save The understanding of the complex structures in the southern margin of Junggar basin is very important to explore the oil traps in the middle-deep strata and discover large oil and gas fields. In this paper, the structural characteristics and evolution of the fold-thrust belt in the southern margin of Junggar basin are studied based on 2D structural sections, quantitative analysis of structural deformation, and the complex structural model and tectonic activity time and deformation mechanism are determined. The research results show that the southern margin of Junggar basin underwent two stages of deformation in the Late Jurassic and Miocene, respectively. Strike slip faults were developed in the Late Jurassic during which Gaoquan fault-uplift zone, Aika structural belt and Qigu-south Anjihai strike-slip fault formed, which were belong to Mesozoic strike-slip fault system in the periphery of Junggar basin. Thrust and fold belt were developed during Miocene. The Cenozoic anticline over-lapped on Gaoquan fault-uplift zone and Aika structural belt in the western section of the southern margin. The drilling of Well Gaotan-1 proves that the anticline structures overlying on the paleostructures are favorable targets for exploration. Three rows of thrust faults and imbricate structures are developed in the middle section of the southern margin, and the middle and lower parts of the structures are the main targets for petroleum exploration. The Cenozoic thrust-fold belt extends from south to north in the southern margin of Junggar basin. Qigu fault-fold zone in the piedmont and the deep folds in the basin formed in the early Miocene (23 Ma), the Huo-Ma-Tu thrust fault occurred at the end of Miocene(7 Ma), and Hutubi anticline and Kayindike anticline formed in Quaternery. Table and Figures | Reference | Related Articles | Metrics

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Geological Characteristics, Resource Potential and Exploration Direction of Shale Oil in Middle-Lower Permian, Junggar Basin ZHI Dongminga, SONG Yongb, HE Wenjunb, JIA Xiyub, ZOU Yangb, HUANG Liliangb null    2019, 40 (4): 1-1.   DOI: 10.7657/XJPG20190402 Abstract （577）      PDF（pc） （300KB）（1184）       Knowledge map    Save The Middle-Lower Permian series, the most important source rocks in Junggar basin, are dominated by multi-source, fine-grained mixed sediments deposited in a terrestrial salty lake environment and have good conditions for shale oil generation. A shale oil province with the OOIP of one billion tons has been discovered in the Lucaogou formation of Jimsar sag. Based on the previous study results and combined with the available geological data, the paper systematically summarizes the geological characteristics of the favorable shale oil areas in the Middle-Lower Permian of the basin. Meanwhile, on the basis of benchmarking with the geological characteristics of the shale oil in the Lucaogou formation of Jimsar sag, the shale oil exploration potential in the Fengcheng formation of Mahu sag and the Pingdiquan formation of Wucaiwan-Shishugou sag is analyzed and the next exploration direction for the shale oil in the basin is discussed. The study results show that the multi-source fine-grained mixed sediments of shore-shallow lacustrine-semi-deep lacustrine facies in the Middle-Lower Permian strata of the basin are the high-quality source rocks where tight sweet-spot reservoirs are developed, and the reservoir combination is characterized by source rock-reservoir superposition and frequent interbed with each other vertically, which lays a foundation for shale oil accumulation in the Middle-Lower Permian strata. Typical terrestrial shale oil characteristics such as hydrocarbon mainly coming from neighboring source rocks, self generation as the complementary and in-situ accumulation can be obviously seen. The maximum proven resources of the shale oil in the basin is 27.25×108 t. The geological conditions of the Fengcheng shale oil in the Mahu sag are better than those of the Lucaogou shale oil in Jimsar sag, therefore, the Fengcheng formation in Mahu sag is considered as the next key area for shale oil exploration. The geological conditions of the Pingdiquan shale oil in Wucaiwan-Shishugou sag are relatively poor, and the shale oil here can only be considered as a prospect area for exploration. Additionally, the Luocaogou formation in the piedmont of Bogda Mountain and the Pingdiquan formation in the slope area of Fukang-Dongdaohaizi sag are the potential areas for shale oil exploration and at present comprehensive geological research should be performed to gain more geological understandings and to complete technical preparation work Related Articles | Metrics

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Subdivisions of the Central-East Asia Multi-Energy Minerals Metallogenetic Domain and Types of Those Basins LIU Chi-yang, QIU Xin-wei, WU Bo-lin, ZHAO Hong-ge Xinjiang Petroleum Geology    2009, 30 (4): 412-418.   Abstract （251）      PDF（pc） （724KB）（1103）       Knowledge map    Save According to the different characteristics of regional structures, basin's evolutions and mineralization conditions, the Central- East Asia energy minerals metallogenetic domain (CEAMD) can be divided into such four mineralization zones as Songliao-Ordos, Alashan-Hexi corridor, Xinjiang and Central Asia ones. The comprehensive analyses and comparisons of accumulation/mineralization conditions and current exploration of multi-energy minerals show that the relatively stable regional tectonic background and moderate (weaker) structural deformation are probably the necessary conditions for the formation, coexistence and preservation of large- and medium-sized sand-type uranium deposits, oil-gas fields and coalfields. The primary basins suitable for coexistence and accumulation of oil-gas, coal and uranium are the large- and medium-sized intracraton basins, intermediate massif basins and correspondingly split medium- and small-sized relic basins. The medium-sized rift basins developed in late of Mesozoic are also of the conditions of accumulation/mineralization and coexistence of multi-energy minerals. Reference | Related Articles | Metrics

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Delineation of the Unconformity Horizon in Upper Jurassic in Jiergelehe Area of Wusu,Xinjiang, China PENG Xi-ling, YUAN Wen-xian, LIU Zhao-rong, LAI Shi-xin, HU Bin Xinjiang Petroleum Geology    2008, 29 (4): 452-456.   Abstract （285）      PDF（pc） （491KB）（805）       Knowledge map    Save There exists a huge unconformity of Upper Jurassic in Tuositai-Jiergelehe area, which was initially classified as the bottom boundary of Qigu formation of Upper Jurassic. But it has been classified as the bottom boundary of Toutunhe formation of Middle Jurassic, and these two formations can not be divided into sub-formations. This paper confirms that the present delineation of the unconformity is a mistake, based on the results from near three-year repetitive investigations. It is concluded that this unconformity does exist between the bottom of Qigu formation and the top of Toutunhe formation. Reference | Related Articles | Metrics

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ROP Improvement and Production Enhancement for Ultra-Deep Wells Based on Geology-Engineering Integration: A Case in Kuqa Depression, Tarim Basin CAI Zhenzhong, XU Ke, ZHANG Hui, WANG Zhimin, YIN Guoqing, LIU Xinyu Xinjiang Petroleum Geology    2022, 43 (2): 206-213.   DOI: 10.7657/XJPG20220212 Abstract （959）   HTML （17）    PDF（pc） （1457KB）（1195）       Knowledge map    Save The Kuqa depression in the Tarim basin is rich in oil and gas resources and has great potential for exploration. However, the geological setting in this area is complex and the target layers are generally buried deeper than 6 000 m, or even more than 8 000 m, making oil and gas exploration and development difficult. Considering the geological engineering characteristics and existing problems of ultra-deep wells in the Kuqa depression, a solution based on the concept of geology-engineering integration is proposed, and the successful practice of the first pre-salt highly-deviated well in Tarim oilfield is introduced. Research and practices show that geomechanical research is beneficial to reducing drilling complexities and increasing rate of penetration, can help select favorable reservoirs and optimize stimulation schemes, and finally support the ROP improvement and production enhancement. The geology-engineering integration is necessary for efficient development of complex oil and gas reservoirs. In this aspect, multiple disciplines will be collaborated in operations through the life cycle of each well to generate the maximum benefits and achieve overall progress from well location deployment, drilling engineering, well completion and stimulation to oil/gas production engineering, thereby facilitating the construction of large oil and gas fields. Table and Figures | Reference | Related Articles | Metrics

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Characteristics and Genesis of Condensate Reservoirs of Lianggaoshan Formation in Fuling Area, Southeastern Sichuan Basin LI Mingyang, LI Chengyin, QU Dapeng Xinjiang Petroleum Geology    2022, 43 (4): 387-395.   DOI: 10.7657/XJPG20220402 Abstract （880）   HTML （16）    PDF（pc） （1211KB）（863）       Knowledge map    Save In the condensate gas reservoirs of the Lower Jurassic Lianggaoshan formation in the Fuling area, southeastern Sichuan basin, the fluid properties are complex and the gas-oil ratios from multi-well testing differ greatly. In this paper, the basic characteristics of oil and gas were clarified by using the data such as crude oil chromatography-mass spectrometry, gas composition, carbon isotopes and fluid inclusions. The gas reservoir properties and phase states were determined with the empirical calculation method for gas compositions and through the experiments simulating PVT fluid phase state. On this basis, the genesis and forming process of condensate gas reservoirs were discussed. The results show that the gas reservoirs in the Lianggaoshan formation are mainly condensate gas reservoirs without oil rings, where hydrocarbons are mainly primary condensate oil and gas generated from Type Ⅱ2 kerogens in the mature stage, and cracking gas is found locally. The thermal evolution degree of source rocks and the differences in the present temperature and pressure conditions of formation are the main contributors to different reservoir properties. The superimposed areas of the relatively deep-burial areas during the hydrocarbon accumulation period on the areas with relatively high pressure at present are favorable targets for future exploration. Table and Figures | Reference | Related Articles | Metrics

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Distribution of Present Geothermal Field and Evaluation of Geothermal Resources in the Western Uplift of the Junggar Basin LU Hui, WANG Fei, ZHANG Yidan, WANG Junwei, ZHANG Jinlong, CHEN Lei, XIAO Bei, YANG Huang, LI Chen Xinjiang Petroleum Geology    2026, 47 (1): 92-102.   DOI: 10.7657/XJPG20260110 Abstract （130）   HTML （3）    PDF（pc） （5134KB）（39）       Knowledge map    Save Geothermal resources, as clean and stable non-carbon-based energy sources, are of great significance for China to achieve its “Dual Carbon” goals. The geothermal resources in the Junggar Basin have been insufficiently studied. This paper discusses the distribution of present geothermal field and performs the evaluation of geothermal resources in the western uplift of the Junggar Basin. Based on the high-quality, continuous temperature measurement data from 11 wells, the distribution characteristics of geothermal gradient and terrestrial heat flow were analyzed. Using the one-dimensional steady-state heat conduction equation, the planar distribution of temperature in the strata shallower than 5 000 m was revealed. On this basis, the geothermal resources of 7 sets of geothermal reservoirs (including the Carboniferous and above systems) were evaluated. The results show that, in the western uplift of the Junggar Basin, the average geothermal gradient is (21.3±3.0) ℃/km, and the average terrestrial heat flow is (43.9±6.9) mW/m2. In the Zhongguai bulge, a relatively high-temperature anomaly area, the average geothermal gradient is (23.3±2.8) ℃/km, and the average terrestrial heat flow is (47.9±5.8) mW/m2. The formation temperature at a depth of 4 000 m ranges from 78.0 ℃ to 122.9 ℃ in the western uplift, with an average of 100.7 ℃ in the Zhongguai bulge, indicating a good geothermal potential. The geothermal resources are estimated to be 411.24 EJ in the study area, with the largest quantity (132.61 EJ) endowed in the Permian, followed by the Carboniferous (121.52 EJ). The largest fluid resources are registered by the Cretaceous, reaching 19.58 EJ. This study provides key parameters for the development and utilization of geothermal resources in the western uplift and also offers a methodological reference for geothermal evaluation in other areas of the Junggar Basin. Table and Figures | Reference | Related Articles | Metrics

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Gravity Flow Research Review and Gravity Flow Type of Baikouquan Formation in Mahu Slope Area KANG Xun1, JIN Jun2, HU Wenxuan1, YANG Zhao2, CAO Jian1, WU Haiguang1 null    2015, 36 (3): 1-1.   DOI: 10.7657/XJPG20150324 Abstract （180）      PDF（pc） （300KB）（891）       Knowledge map    Save The history and actuality of gravity flows researches at home and abroad were reviewed, including the gravity flow formation mechanism, sedimentary process and development sequence, etc., and the classification models and identification characteristics of gravity flows were analyzed, pointing out the possible gravity flow types in glutenite combination. Based on these results, the development characteristics and depositional fabrics of Baikouquan glutenite in Mahu slope area of Junggar basin were systematically observed and studied. It is suggested that five types of gravity flows, such as debris flow, grain flow turbidity current, flood mudflow and sandy debris flow, are mainly developed in the Baikouquan formation. According to the typical cores lithology descriptions, the identification marks for various gravity flows are presented, and the corresponding sedimentary sequence models are established in this paper Related Articles | Metrics

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SubLayer Correlation Method and Application Based on Braided River Outcrop Geometric Model: A Case Study of Enping Formation in Oilfield A, Pearl River Mouth Basin JU Zilong1, TANG Hui1, LIU Weixin1, DAI Zong1, CHEN Cheng2, LI Qingmin1 null    2016, 37 (2): 1-1.   DOI: 10.7657/XJPG20160210 Abstract （182）      PDF（pc） （300KB）（556）       Knowledge map    Save From the braided river outcrops of Houcheng formation of Middle Jurassic at Junzhuang town, Mentougou region in Beijing, it is observed the cross?section of the braided river distributary channel is characterized by gradual thinning of thickness from channel center to channel wings. Considering the channel changing system, this paper presents the geometric model of the cross?section is that besides the thinning feature, it appears the unsymmetric semi?ellipse with flat top and swell bottom. Using the geometric model and the conventional “sand to sand and shale to shale”sub?layer correlation methods, the correlation of single sand body sublayer of the Enping formation in oilfield?A braided river sedimentary system in Pearl River Mouth basin is conducted. The result shows that the geometric model?based sublayer correlation method can be applied to explain the lateral difference between sand body number and sand thickness of interwells and longitudinal evolution pattern of the sedimentary center through the spatial distribution characteristics of braided river channels, and is more applicable in study of complicated sedimentary system like braided river, compared with conventional sub?layer correlation method Related Articles | Metrics

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Application of Multistage Acid Fracturing Technology for Horizontal Well to UltraDeep Fractured Carbonate Reservoirs ZHANG Bo1,2, XUE Chengjin1, ZHOU Linbo1, ZHANG Ye2,3 null    2013, 34 (2): 1-1.   Abstract （180）      PDF（pc） （300KB）（1100）       Knowledge map    Save The Ordovician carbonate reservoir in Tarim oilfield is dominated by fractures and solution pores and cavities and characterized by ultra?deep, high pressure and high temperature, of which the most fractures with medium?high angle are as both reservoir spaces and the main flow channels. But since such a reservoir is of low pore?throat coordination and poor connectivity, acid fracturing process has to be needed to build its productivity. The main factors affecting the effect of acid fracturing include the selection of acid fracturing process for the long openhole interval and that the acid?etching fractures can communicate the effective fracture?cave reservoir or not. For these reasons, this paper conducts such parameters optimizations as acid?etching fracture length, fluid conductivity, stimulation scale, prepad fluid ratio and expelling amount, etc., and then selects the fracturing and acid liquids to form a differentiated and multistage acid fracturing optimization design scheme. The field application indicates that the designed parameters are reasonable and effective, and the multi?stage acid fracturing technology is suitable for stimulation of the ultra?deep fractured carbonate reservoirs Related Articles | Metrics

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Classification of Low-Permeability Sandstone Reservoirs and Permeability Evaluation by Well Logging: A Case from the Reservoir of Toutunhe Formation in Wellblock Shinan-21 FENG Lijuan, JIANG Zhibin, QIAN Chuanchuan, SU Haibin, WANG Jie, LIU Gang null    2018, 39 (2): 1-1.   DOI: 10.7657/XJPG20180206 Abstract （195）      PDF（pc） （300KB）（482）       Knowledge map    Save The low-permeability sandstone reservoir of Toutunhe formation in Wellblock Shinan-21 of Junggar basin is characterized by strong heterogeneity and great physical property differences in profile. Based on physical property analysis and the data of mercury injection and casting thin section, regarding microscopic pore-throat structures of the reservoir, the reservoir can be divided into 4 types through parameter optimization by using cluster analysis method. The Toutunhe formation in Wellblock Shinan-21 is dominated by Type Ⅱ and Type Ⅲ reservoirs that are mainly influenced by shale content. The larger the shale content is, the poorer the pore structure and the lower the permeability will be. The error of permeability of shaly sandstone reservoir interpreted with conventional model is relatively large. According to shale content and combining with reservoir classification, the paper establishes 4 permeability interpretation models for the 4 types of reservoirs, respectively. The actual application shows that the new models can well match with core analysis data, the interpretation accuracy is improved by 7.8% compared with that of the conventional model and good effects have been gained, which can be widely used for other low-permeability shaly sandstone reservoirs Related Articles | Metrics

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Using Micro-CT Scanning Technology to Study Characteristics of Pore Structures in Sandy Conglomerate: A Case from Baikouquan Formation in Mahu Sag, Junggar Basin XIONG Jian1, TANG Yong2, LIU Xiangjun1, QU Jianhua2, LIU Kai1, YOU Xincai2 null    2018, 39 (2): 1-1.   DOI: 10.7657/XJPG20180218 Abstract （283）      PDF（pc） （300KB）（1199）       Knowledge map    Save Taking the sandy conglomerate reservoir of Baikouquan formation in Mahu sag as the study objects, micro-CT scanning technology is used to investigate the characteristics of the 2D and 3D pore structures of the rock in the sandy conglomerate reservoir. The results indicated that the sandy conglomerate sample obtained from Baikouquan formation in Mahu sag is dominated by residual intergranular pores, dissolved pores and micro-cracks. The shapes of the pores are irregular, the pore throats are of different sizes and their distributions are mainly contiguous and isolated; microscopic heterogeneous pore distribution is noted and even obvious in the samples with poor physical properties; equivalent pore radius is mainly in unimodal distribution and mostly less than 50 μm, and the proportion of small pores in the samples with relatively poor physical properties is higher than that in the samples with good physical properties Related Articles | Metrics

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Diagenesis in Alkaline Environment and Its Influences on Reservoir QualityA Case Study of Middle-Lower Permian Clastic Reservoirs in Northwestern Margin of Junggar Basin SHAN Xiang, GUO Huajun, ZOU Zhiwen, LI Yazhe, WANG Libao null    2018, 39 (1): 1-1.   DOI: 10.7657/XJPG20180107 Abstract （209）      PDF（pc） （300KB）（649）       Knowledge map    Save Based on the data of cast thin section, SEM, Electronic probe, X-ray diffraction and petrophysical properties etc., the paper detailedly studies the petrologic features and diagenesis of the Middle-Lower Permian clastics in the northwestern margin of Junggar basin, based on which, the influence of the diagenesis in alkaline environment on accumulative properties of reservoirs is discussed. The results show that the diagenesis in alkaline environment is commonly noted in the Middle-Lower Permian strata, such as tephra hydrolysis, tephra albitization, formation of zeolites and chlorite and so on. Various associated pores including alkaline dissolved pore of tephra, albitized associated pore and intercrystalline micropore in clay minerals are developed in alkaline environment. The influences of diagenesis in alkaline environment on the Middle-Lower Permian clastic reservoirs mainly include strong impaction of reservoir fluids resulted from alkaline fluids, i.e., high reservoir compaction ratio in alkaline fluids, which is unfavorable for primary pore preservation; high authigenic mineral content of reservoir under the diagenesis in alkaline environment and local cementation with large pore reduction amounts; high pore increase efficiency due to the corrosion of alkaline fluid. Alkaline dissolved pore in tephra can be the important accumulation space Related Articles | Metrics

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A CALCULATION METHOD OF FLUID PHASE EQUILIBRIUM OF KEKEYA CONDENSATE POOL Du Junshe Xinjiang Petroleum Geology    1992, 13 (3): 263-269.   Abstract （242）      PDF（pc） （420KB）（474）       Knowledge map    Save The phase equilibrium calculation of Kekeya condensate pool has been made using a hybrid method of the equation of state. That is accelerated iteration and interpolation in place of iteration step by step, of which a similar matrix has been adopted rather than a reverse one of Jacobi' s matrix that could hardly allow for giving solution with gradient method. The result shows that this method has advantages of fastly calculating speed and fairly good stabilities. Reference | Related Articles | Metrics

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Stratigraphic Classification and Correlation of Cambrian in Bachu Uplift, Tarim Basin CAI Xi-yao, MAO Shu-hua, QIAN Yi-xiong, CHEN Yue, YOU Dong-hua Xinjiang Petroleum Geology    2009, 30 (1): 38-42.   Abstract （300）      PDF（pc） （509KB）（1121）       Knowledge map    Save The Cambrian rocks commonly occured in the wells of Buchu uplift in Tarim basin could be divided into three series and seven members. They are clastic member, dolomite member and gypsum-bearing dolomite member in the lower series; subsalt carbonatite member, gypsum-salt member and gypsum-bearing dolomite member in the middle series, and pure dolomite member in the upper series, based on their obviously different electrical properties. The abundance fossils of small shell and algae found in the clastic member are discussed in space-time distribution in detail, and the age of the strata with small shell is determined as the early of Early Cambrian in wells of Bachu uplift. The outcrop section correlation shows that the clastic member and Yurtus formation belong to the relation of the same age but different facies. The subsalt carbonatite member corresponds to Shaylik formation, which can be considered as marker bed for formation correlation in this area. In addition, according to seismic sequence stratigraphy, the Cambrian strata can be divided into three super-sequences which correspond to three series; in terms of drilling sequence stratigraphy, it can be two and half super-sequences and five sequences. The classification and the correlation of the Cambrian strata in this area establish a stable stratigraphic foundation for further studies related to Bachu uplift. Reference | Related Articles | Metrics

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Evaluation Method for Economic Benefit of Secondary Development in Karamay Oil Field ZHANG Yu, WANG Jian-feng, XIANG Qian, ZHOU Chun-xia, LIU Bin, ZHANG Jun, QIU Yang Xinjiang Petroleum Geology    2010, 31 (5): 551-553.   Abstract （250）      PDF（pc） （211KB）（681）       Knowledge map    Save This paper elaborates the targets, project contents, necessity and features of secondary development in Karamay oil field, analyzes the significant distinctions of economic benefit evaluation between the secondary development projects and the ordinary projects and draws up the case history of specific evaluations. This research has been applied to the secondary development work in this field and has important significances on research of development adjustment in old oil fields, stabilization of production in existing blocks, enhancement of oil recovery in the reservoirs and proper understanding of economic benefit of the secondary development. Reference | Related Articles | Metrics

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Petroleum Exploration History and Enlightenment of Yanchang Exploration Area in Ordos Basin HU Chunqiao, REN Laiyi, HE Yonghong, WAN Yongping, LIANG Quansheng Xinjiang Petroleum Geology    2021, 42 (3): 312-318.   DOI: 10.7657/XJPG20210307 Abstract （954）   HTML （10）    PDF（pc） （4789KB）（1064）       Knowledge map    Save During the 100-year history of oil and gas exploration in Yanchang exploration area of Ordos basin, a number of major progress and breakthroughs have been made, all of which are of great significance. After analyzing the exploration history, data and important historical events, and based on the variations of oil and gas production and the development of geological theory in Yanchang exploration area, the exploration process is divided into four stages: Early exploration stage (1905-1949), sustained exploration stage (1950-1981), rapid development stage (1982-2006) and stabilizing oil production meanwhile increasing gas production stage (2007-). Additionally, this paper summarizes the theories and understandings in exploring ultra-low-extra-low permeability reservoirs, tight gas and continental shale gas in the southeastern area of the Ordos basin in recent ten years, and analyzes their important roles in the rapid increase of oil and gas reserves and production. Our findings may provide implications and references for future oil and gas exploration. Table and Figures | Reference | Related Articles | Metrics

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Petroleum Exploration History and Enlightenment in Hailar Basin LI Chunbai Xinjiang Petroleum Geology    2021, 42 (3): 374-380.   DOI: 10.7657/XJPG20210314 Abstract （853）   HTML （10）    PDF（pc） （1645KB）（800）       Knowledge map    Save After looking back the oil and gas exploration history and summarizing the geological understanding, engineering technology and important exploration results in the Hailar basin since the 1950s, the exploration process of the Hailar basin can be divided into four stages, namely regional exploration for oil and gas discovery, structural reservoir exploration for breakthrough, fault-block reservoir and lithologic reservoir exploration for reserves increase, and multi-type reservoir exploration for further expansion. Many years of exploration practice proves the following conclusions: (1) Every innovation in understanding and every change in thinking bring new portunities to exploration; (2) Breakthrough to key seismic technologies can effectively improve geophysical imaging quality and lay a foundation for deepening understanding of complex structural zones in complex faulted basins; (3) The prototype basin controls the formation and evolution of source rocks, and the structural belts in sags control the migration and enrichment of oil and gas, so that the optimal selection of major sags and the clear understanding of reservoir forming controlled by faults and structures are the basis and key points guiding exploration; (4) Understanding oil and gas enrichment laws in subsag-slope zones allows the changes of exploration ideas and expansion in exploration field and space; (5) The innovation in the understanding of geological theory is fundamental for widening exploration field and making sustainable discoveries, and it is also helpful to broaden our mind and encourage innovation in future exploration. Table and Figures | Reference | Related Articles | Metrics

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Classification of Sweet Spots in Shale Oil Reservoir of Lucaogou Formation in Jimsar Sag，Jurggar Basin QI Hongyan, WANG Zhenlin, ZHANG Yanning, LIN Jingqi, HU Xuan, SU Jing, XU Rui, CAO Zhifeng Xinjiang Petroleum Geology    2025, 46 (2): 127-135.   DOI: 10.7657/XJPG20250201 Abstract （814）   HTML （37）    PDF（pc） （3916KB）（374）       Knowledge map    Save The shale oil reservoir of Permian Lucaogou formation in the Jimsar sag of the Junggar Basin can be divided into two sweet spots from top to bottom. These sweet spots vary significantly in productivity and remain unclear for controlling factors, making sweet spot prediction challenging. By using geological, petrophysical experiment, logging, and formation testing data, the enrichment mechanisms of shale oil were identified, the main factors controlling sweet spots in the shale oil reservoir were investigated, sweet spot index was constructed, and a classification standard for sweet spots was established. The research results show that the dominant reservoir rocks in the sweet spots in the study area are silty-fine sandstone and psammitic dolomite, with good pore structure, relatively abundant free oil, and moderate brittleness. The development, distribution, and effectiveness of micro-fractures in the shale oil reservoir are influenced by formation overpressure. The sweet spots in the shale oil reservoir are mainly controlled by free oil saturation, formation overpressure, and brittleness index. The sweet spot index is greater than 45 for Class Ⅰ sweet spots, 25-45 for Class Ⅱ sweet spots, and less than 25 for Class Ⅲ sweet spots. Class Ⅰ and Class Ⅱ sweet spots are considered as prime targets for horizontal wells, while Class Ⅲ sweet spots are reserved for future development. Table and Figures | Reference | Related Articles | Metrics

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Discovery of Kelasu Subsalt Deep Large Gas Field, Tarim Basin YANG Haijun, LI Yong, TANG Yan'gang, LEI Ganglin, ZHOU Lu, ZHOU Peng Xinjiang Petroleum Geology    2019, 40 (zk(English) ): 12-20.   Abstract （218）      PDF（pc） （5710KB）（503）       Knowledge map    Save Kelasu tectonic belt is located in the northern Kuqa depression and the discovered subsalt large-deep gas field in the tectonic belt belongs to ultra-deep high-pressure gas fields with low-porosity high-yield fractured sandstones. Up to now 22 oil and gas reservoirs have been discovered in the gas field, which are the major production areas for natural gas in Tarim basin. There was no significant break-through after the discovery of Kela 2 gas field in 1998. Since 2006, the research of the deep zones in Kelasu tectonic belt has been strengthened, and in Aug., 2008 commercial gas flows were gained from the Cretaceous Bashijiqike formation in the Well Keshen-2 which is located in the Keshen-2 structure of Keshen area and the daily gas production was 40×104 m3, marking a great breakthrough has been gained. Then over 10 years of study, technological breakthroughs have been made on foreland basin exploration technology, petroleum geological theory and production practice, which provides guidance for the discovery of the Kelasu subsalt deep large gas field. The researches on trap identification in complex mountain areas, reservoir forming mechanism and hydrocarbon accumulation, speedy drilling and reservoir reformation effectively support the efficient exploration and development of the Kelasu subsalt deep large gas field. Reference | Related Articles | Metrics

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Study on Water Invasion Pathways in the Southwest Flank of Kela-2 Gas Field Based on DAS Microseismic Inversion ZHU Songbai, WANG Shengjun, LIN Na, NIE Yanbo, FAN Qiuhai, WU Weimin, WANG Jinbing, LU Jianrong Xinjiang Petroleum Geology    2026, 47 (3): 300-306.   DOI: 10.7657/XJPG20260306 Abstract （114）   HTML （17）    PDF（pc） （2061KB）（50）       Knowledge map    Save During long-term development of the Kela-2 gas field, edge/bottom water migrated along water invasion pathways toward production wells, causing a varying degree of water breakthrough in most wells, which has adversely affected the gas field development. Currently, there is a lack of effective methods for delineating water invasion pathways. To address this limitation, a numerical model of coupled gas-water two-phase flow-stress was established to simulate the coupled flow-stress field, fault deformation, and induced microseismicity during gas field development. Based on the 3D spatial distribution of observed microseismic events, the Mahalanobis distance-based objective function was constructed to align the 3D coordinates of microseismic events recorded by distributed acoustic sensing (DAS) with those generated by the numerical simulation. Then, the objective function was minimized by iteratively adjusting the initial permeability distribution of both the matrix and fractures until a convergence was achieved. Finally, the optimal permeability distribution and the coupled gas-water two-phase flow-stress field were analyzed to identify potential water invasion pathways. The results show that, in 2015, localized segments of faults F159 and F160 began activating, exhibiting an average shear-slip rate of 1 mm/a, and an average permeability of approximately 100 D. Two active aquifers exist in the southeastern and southwestern parts of the southwest flank of the Kela-2 gas field, and they spatially coincide with the activated segments of faults F159 and F160. Edge/bottom water intruded into reservoirs through these activated segments and subsequently migrated via high-permeability channels to Wells KL205, KL2-7 and KL2-8. The edge/bottom water rose vertically at a rate of 3 m/a, and migrated horizontally at a rate of 50 m/a. Three distinct water invasion pathways have been identified in the southwest flank of the Kela-2 gas field. These findings provide valuable insights for predicting the timing and extent of water breakthrough in gas wells, designing effective water management and drainage strategies, and improving overall production efficiency. Table and Figures | Reference | Related Articles | Metrics

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NMR Logging Permeability Prediction Method Based on Dynamic Pore Structure Efficiency ZHU Linqi1,2, ZHANG Chong1,2, HE Xiaoju1,2, CHEN Yulong1,2, WEI Yang1,2, YUAN Shaoyang1,2 null    2015, 36 (5): 1-1.   DOI: 10.7657/XJPG20150521 Abstract （226）      PDF（pc） （300KB）（710）       Knowledge map    Save Traditional NMR logging permeability models are always poor in application effect to tight sandstone reservoir. Considering the affects of formation pore?throat structure, pore space distribution, pore specific surface area on tight sandstone reservoir permeability, this paper proposes NMR logging permeability prediction method based on dynamic pore structure efficiency by means of theory of equivalent rock composition, and presents the model using29rock samples. In order to improve the prediction accuracy of the irreducible water saturation and the pore structure efficiency in this model, it gives such idea for evaluation of these two parameters as using T2 geometric mean value and4~32ms NMR porosity to build BP neural network for point?by?point prediction T2 cutoff value, and then taking the T2 cutoff value as intermediate parameter to get the irreducible water saturation and the porosity structure efficiency. The handling of the data proves that this model is of higher calculation accuracy than SDR and Coates models, and can be applied to permeability calculation of tight sandstone reservoir, and helpful to the productivity evaluation of the reservoirs Related Articles | Metrics

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An Approach to the Origin of Volcanoes HU Dao-xiong Xinjiang Petroleum Geology    2011, 32 (5): 564-568.   Abstract （392）      PDF（pc） （222KB）（1231）       Knowledge map    Save Volcano is one of exiting modalities of substances redistribution in the earth. The origin of volcano results from that the state of the mantle solid substance is changed, resulting in substances' differentiation. When it happens, displacement reaction of substances appears on top of the mantle. And then the load of displacement space will decrease, causing the buoyancy increasing. In the end, volcanic eruptions will happen. There are basic conditions for the formation of volcanoes, namely, displacement substances, displacement space and eruption channels. There are five existing states of volcanoes: perennial, intermittent, opening, ending and under-erupted ones, which are highly related with the velocity of substance displacement. And it keeps a close relationship with the velocity of solid substances' state change. Volcanic eruption results from substances emission in the earth, which can also cause volumetric change of the earth, namely crust movement. Intensity of volcanic eruption is in proportion to the thickness of the crust. If the crust is thinner, volcanic eruption can not happen but only overflow. And if the crust is thicker, greater pressure will produce in the displacement space. Pressure inside of the volcano is closely related with displacement height and density of the substance, by which the pressure can be calculated. Distributions of volcanoes are also interrelated to the distribution of solid substances of the mantle. And the distribution of the volcanoes in geohistory periods is strongly affected by the degree of impinging planetesimals, and that in later periods is mainly affected by subducted plates. Reference | Related Articles | Metrics

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Oil and Gas Distribution in Devonian Donghe Sandstone of Tarim Basin LI Jingchang, CHEN Yuanzhuang, HE Hong, SONG Haiming, XU Jie, WU Jiang null    2017, 38 (5): 1-1.   DOI: 10.7657/XJPG20170501 Abstract （280）      PDF（pc） （300KB）（630）       Knowledge map    Save In order to further illuminate the oil and gas distribution of the Devonian Donghe sandstone, and to explicitly determine the oil-gas exploration direction in Tarim basin, the paper analyzes the data related to the hydrocarbon accumulation in Donghe sandstone, and studies its hydrocarbon accumulation characteristics and oil-gas distribution. It is concluded that the oil and gas distribution in Donghe sandstone of Tarim basin is controlled by fault belt of Hercynian movement period and stratigraphic pinchout. Wether the traps constrained by the structures of Hercynian movement period could trap oil and gas or not depends on the trap sizes and the distance from oil source, and the eastern section of the Selibuya fault belt is the favorable area for oil and gas exploration. Wether the traps controlled by stratigraphic pinchout could trap oil and gas or not depends on the lithologies of the trap floor and their positions in structures, and the southern and northern sides of Shuntuoguole low uplift and the northern Awati depression are the most favorable areas for oil and gas exploration Related Articles | Metrics

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Organic Matter Enrichment and Hydrocarbon Source Rock FormingMechanism in Small-Scale Faulted Lacustrine Basins:A Case from the Frist Member of Lower Cretaceous Tenger Formation in Erlian Basin DING Xiujian1, LIU Guangdi2, ZHAO Longmei3, GAO Dengkuan4, ZHANG Kai5, KUANG Daqing6 null    2017, 38 (6): 1-1.   DOI: 10.7657/XJPG20170604 Abstract （282）      PDF（pc） （300KB）（685）       Knowledge map    Save To recognize forming mechanism of source rocks in small-scale faulted lacustrine basins, the paper studies formation, distribution and geochemical characteristics of source rocks, and establishes 3 source rock formation patterns in small-scale faulted lacustrine basins by integrating the influences of organic matter supply, preservation and dilution on source rock forming. In a lacustrine basin with active boundary fault and high depositional rate, organic matter supply is sufficient but its preservation condition is poor, the source rock is mainly constrained by the organic matter supply and is mainly developed in deep depressions with abundant organic matter supply; in a lacustrine basin with inactive boundary fault and low depositional rate, the organic matter supply is of small quantity and its preservation condition is good, the source rock is mainly controlled by organic matter preservation conditions and is mostly distributed in gentle slopes with high reduction degree; in a lacustrine basin with moderate-active boundary fault and moderate depositional rate, the organic matter supply is of large quantity and its preservation condition is relatively good, the source rock is controlled by depositional rate, organic matter supply and preservation, and is developed in both deep depressions and near-depression gentle slopes. Related Articles | Metrics

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Geometry and Kinematics of Wensu Swell in North Tarim Uplift CHEN Jiajun, HE Dengfa, SUN Fangyuan, HE Lei null    2018, 39 (3): 1-1.   DOI: 10.7657/XJPG20180309 Abstract （220）      PDF（pc） （300KB）（236）       Knowledge map    Save Wensu swell is located in the northwestern margin of Tarim basin, which belongs to western segment of North Tarim uplift. As a part of paleo-uplift in the cratonic basin, Wensu swell is an ideal object for studying the deformation behaviors in the interior of tectonic plates. Based on drilling data, logging information, 2D seismic data, Digital Elevation Model（DEM）and geological map and combining with the stratigraphic texture of periphery areas, the paper characterizes the geometries of Shajingzi boundary fault and Wensubei fault detailedly, and establishes a geometric and kinematic model with the guidance of fault-related fold theories. The study results suggest that Wensu swell is an inherited upwarping zone controlled by Shajingzi fault, Wensubei fault and basement uplift. Shajingzi fault was developed as fault propagation fold mode at the early stage, then broke through along the forelimb of the fold at the late stage and transtensional faults occured during the late Quaternary. Wensu swell formed at the end of Early Ordovician; its structure was shaped under the influence of the closing of South Tianshan Ocean at the end of Permian; Wensu swell stepped in relative tectonic silence stage during Mesozoic and strongly deformed due to the South Tianshan orogenesis during Cenozoic. Wensu swell and the peripheral area are shortened by about 35.40 km totally. Fine fault analysis, especially the staged fault analysis can be a breakthrough method to analyze complicated structures Related Articles | Metrics

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Logging Evaluation for Sandstone Reservoirs in Bashijiqike Formation of Keshen Area, Kuqa Depression XIN Yi1, TANG Jun2, LUO Zhenyuan1, BIE Kang1, TANG Baoyong1, LI Xiaolong1 null    2019, 40 (1): 1-1.   DOI: 10.7657/XJPG20190118 Abstract （204）      PDF（pc） （300KB）（543）       Knowledge map    Save The Bashijiqike formation in the Keshen area of the Kuqa depression in the Tarim basin has an average burial depth of more than 6 000 m, which belongs to deep-burial low-porosity and ultra-low permeability sandstone reservoirs. The variations of the reservoir lithologies have significant influences on logging responses and reservoir physical properties such as porosity and permeability. The elemental capture spectrum logging and micro-resistivity imaging logging are used to accurately characterize lithologies, and the logging evaluation parameters that can reflect mineral compositions and rock particle distribution are selected, and according to particle sizes the models for porosity and permeability calculation in the Keshen area are established to improve the accuracy of reservoir physical property evaluation. The logging parameters that can characterize the petrological characteristics of the reservoir are extracted by introducing the concept of lithology-lithofacies. Based on the data of elemental capture spectrum logging and imaging logging and the comprehensive consideration of lithology, grain size and sedimentary structure, a reservoir lithology-lithofacies division standard is established for the Bashijiqike formation in the Keshen area. The application of the method in the reservoir evaluation in the Keshen area has gained good results, which could provide references for the evaluation of low-porosity, low-permeability reservoirs with large lithology variations Related Articles | Metrics

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Characteristics of Pores and Throats Distribution in Tight Sandstone Reservoir WU Luofei1, SHI Yongmin1, MA Wei2, XIONG Wentao1, GUO Xinwei1 null    2013, 34 (4): 1-1.   Abstract （143）      PDF（pc） （300KB）（552）       Knowledge map    Save Taking Chang?6 tight sandstone reservoir in one field of mid?eastern Ordos basin as an example, with many experimental means such as FE?SEM, rock and cast sections, mercury injection and NMR, etc., this paper discusses in detail the pores and throats features in tight sandstone reservoir and suggests that the composite effects of pores and throats are significant to the development of such a reservoir.The static geological model for this reservoir can not well match with the micro?pores and throats by cell unit size, which is the primary cause resulting in limitation of reliability and accuracy, while using mean cell unit size of micro?pores and throats could more directly and properly characterize the heterogeneity of the tight sandstone reservoir Related Articles | Metrics

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A Rock Static Brittleness Index Calculation Method Considering Burial Depth Correction: A Case Study of Permian Lucaogou Formation in Jimsar Sag LI Guoxing1, MAO Rui2, WANG Zhenlin2, MU Liwei2 null    2018, 39 (5): 1-1.   DOI: 10.7657/XJPG20180517 Abstract （271）      PDF（pc） （300KB）（656）       Knowledge map    Save Based on the data of dynamic and static rock mechanics experiments and other supporting experiments, the ratio of Young’s modulus to Poisson’s ratio is preferred as the method to characterize the static brittleness index, a dynamicstatic brittleness index conversion model based on porosity and clay content is established and the static brittleness index can be calculated. Finally, the influence of burial depth on brittleness indexes is studied, burial depth correction is performed, and then a relatively sophisticated rock static brittleness calculation method considering burial depth correction is established on the basis of logging data. The calculation results of the rock brittleness are consistent with the results of core static brittleness experiment in the study area, and the method has been widely used in production Related Articles | Metrics

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Application of Geology-Engineering Integration in Efficient Exploration in Structure KS24 YIN Guoqing, ZHANG Hui, WANG Haiying, WANG Zhimin, LIU Xinyu null    2019, 40 (4): 1-1.   DOI: 10.7657/XJPG20190415 Abstract （233）      PDF（pc） （300KB）（727）       Knowledge map    Save Aiming at well location deployment, drilling speed increasing and well-completion production improvement in the Structure KS24 of Kelasu tectonic belt in the piedmont area of Kuqa depression during exploration, an analysis on the three aspects is carried out from the perspective of geology-engineering integration. In the stage of well location deployment, it is predicted that the faults controlling the structure have good sealing and is conducive to oil and gas preservation. On the basis of geological prediction and geomechanical research, the borehole stabilities are identified for shallow high-steep interval, gravel interval, mudstone interval, gypsum interval and fractured sandstone interval, and measures for optimizing drilling fluid performance are proposed. In the well completion stage, according to the geomechanical characteristics, a reasonable production improvement mode is formulated, and the stimulated interval, operation pressure and perforation cluster are optimized. According to the research results, 9 wells such as Well KS24 and Well KS241 etc. have been drilled successively and no abnormalities occur. The drilling speed is increased by 39% in average, which creates a drilling record in Kelasu tectonic belt. Different stimulation methods are adopted in the 5 drilled wells, the average gas well production is 31×104 m3/d, the average open flow capacity is 170×104 m3/d, and both the exploration success rate and high-yield well rate reach 100%. During the exploration practices in the Structure KS24, a procedure of geology-engineering integration study and its application has been established, and has been combined into well location deployment-drilling and engineering integration, which has become an effective mean to solve exploration and development problems under complex geological conditions Related Articles | Metrics

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Performance and Oil Displacement Effect of Polymer Microsphere Additive System REN Hao1, ZHANG Zuowei2, WANG Jian3, GUAN Dan1, QUE Tingli1, YU Heng4 null    2019, 40 (5): 1-1.   DOI: 10.7657/XJPG20190514 Abstract （316）      PDF（pc） （300KB）（1728）       Knowledge map    Save In order to improve the effects of waterflooding and polymer flooding in Pu125 block of Pubei oilfield, it is proposed to use polymer microsphere additive system to improve the technology. Under the simulated reservoir conditions, the performance of the additive system was evaluated, and its microstructure was analyzed to study its oil displacement effect. The experimental results show that the polymer microsphere additive system under the reservoir condition has a viscosity of 114.3 mPa·s, which has good temperature adaptability, mineralization adaptability and long-term stability. Its shear resistance is better than that of polymer solution; the microstructure of the additive system is that the microspheres are dispersed and adsorbed on the branches of the polymer network structure, which not only improves the viscosity of the polymer, but also enhances the dispersion of the microspheres; the efficiency of the additive system is better than that of polymer system. After the injection of the additive system, the distributing rates of the high and low permeability layers are about 50%, respectively. Compared with polymer-only flooding, the additive system can better improve the development effect and the recovery factor of high watercut reservoirs Related Articles | Metrics

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Comparative Analysis of Isothermal Adsorption Models for Shales and Coals ZHAO Tianyi, NING Zhengfu, ZENG Yan null    2014, 35 (3): 1-1.   Abstract （316）      PDF（pc） （300KB）（1789）       Knowledge map    Save The experimental data of CH4 adsorption on coals and shales are fitted by using Freundlich empirical formula, Langmuir model, extended Langmuir model, Toth adsorption model and Langmuir-Freundlich adsorption model. The fitting degrees is also examined. The results show that both the coal and the shale, the fitting precision of three?parameter model is higher than that of two?parameter model. For the two?parameter models, the fitting degrees of Langmuir model on coal and shale is much higher than the Freundlich empirical formula model by more than 8 times. For the three?parameter models, their fitting degrees are all higher, of which Toth model is the highest in fitting degree than E?F and L?F models at an averge temperature for shales, but for coals, it is lower than the other two. On the whole, Toth model and L?F model are better for fitting of coals and shales rather than Freundlich empirical formula. The study results are of guiding significance in proper selection of isothermal adsorption model for coals and shales Related Articles | Metrics

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Unconformity Types and Erosion Thickness Restoration in Nanpu Sag, Huanghua Depression, Bohai Bay Basin PENG Qinghua1, ZHOU Jiangyu2, JIANG Shaobin3a, WANG Yumei3b, MA Yueqin3b null    2013, 34 (6): 1-1.   Abstract （188）      PDF（pc） （300KB）（881）       Knowledge map    Save Nanpu sag underwent multi?stage extensional subsidence and uplifting?erosion cycle evolution, formed six regional unconformities, which can be divided into two categories: parallel unconformity and truncation unconformity. The former includes the Carboniferous bottom and the Mesozoic bottom unconformities; the latter includes the Cenozoic bottom, the Shahejie formation member?1 bottom, the Dongying formation bottom and the Guantao formation bottom ones. The control effects of these unconformities on hydrocarbon accumulation in the study area are mainly manifested in the following three aspects: reservoir reconstruction, as the oil and gas migration channels and sealing. Vitrinite reflectance trend line method is used to recover the erosion thickness of Dongying formation in Gaoshangpu area, Combined with interval transit time method and stratigraphic correlation method, the erosion thickness of Dongying formation in other areas of Nanpu sag has been recovered. The study shows that the erosion intensity of Dongying formation in Nanpu sag could be divided into two districts: the strong erosion district in the northeast part and the week erosion district in the north?central part. Overall, the Dongying formation in Nanpu sag has suffered from erosion, its structural high is big, and its central sag area is small in denudation quantity Related Articles | Metrics

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Discussion on Genesis of Red Beds of Jurassic in Yongjin Area in Junggar Basin HE Zhen-jian Xinjiang Petroleum Geology    2009, 30 (1): 133-135.   Abstract （349）      PDF（pc） （240KB）（847）       Knowledge map    Save The red sandy mudstone deposit (red beds) occurs in the top of Jurassic in Yongjin area of Junggar basin. Based on the core observation, change of clay mineral composition, oxide ratio and chemical alteration index analysis, the red beds are normal sedimentary rocks formed in the shore-shallow lake or braided delta front environment, followed by being oxidized while migration and deposition under the semiarid-subhumid climate. The result shows that the red beds are in weak chemical weathering and leaching process without weathering crust. It is suggested that the red beds should belong to Toutunhe formation of Middle Jurassic. The Che-Mo palaeohigh developed in late of Middle Jurassic is of short-term subsidence and then uplift features. Reference | Related Articles | Metrics

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Improvement and Application of Reservoir Size Sequential Method LI Xiao-guang, LU Gang, SHAN Jun-feng Xinjiang Petroleum Geology    2009, 30 (1): 106-108.   Abstract （281）      PDF（pc） （288KB）（443）       Knowledge map    Save The reservoir size sequential method is an important method for petroleum resource estimation. However, with this method irrational predicted results are often gained by selecting value k in terms of minimum standard error as principle. This paper proposes an improved algorithm in terms of k-line chart concept and "1-2-2 principle" for determine value k. The numerous testing results indicate that "1-2-2 principle" combined with k-line chart will be more reasonable to give value k, and more helpful to improve the predicted precision. Reference | Related Articles | Metrics

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Geochemical Feature of Low-Mature Crude Oil in Sub-Sag of Guanzhen in Subei Basin YANG Bin, LIANG Xing, MA Xiao-xiang, ZHOU Songyuan, LOU Ji-sheng, CAI Ya-ping Xinjiang Petroleum Geology    2008, 29 (5): 553-556.   Abstract （274）      PDF（pc） （310KB）（502）       Knowledge map    Save The sub-sag of Guanzhen is located in middle part of Hongze sag in Yanfu depression, Subei basin. Its low-mature crude oil is characterized by the "four highs and one low" physical properties: the middle-higher crude density, high viscosity, high solidification point, high paraffin content and low sulfur content. The oils in wells in this sub-sag are not subjected to biodegradation, with the typical low-mature oil feature of their group compositions, which are proved by low degree of the thermal evolution data of light hydrocarbons including sterane, low m(Pr)/m(Ph) and high m(Ph)/m(nC18) ratios. The m(Pr)/m(Ph) ratio indicates the crude is product from the reductingstrong reducting environment and dominated by sapropelic kerogen. The high paraffin content of crude oils is related to those that a part of humic kerogen formed oil in low-mature stage and botryococcane in saprogelic kerogen early formed oil. Reference | Related Articles | Metrics

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Characteristics of Alkaline Minerals and Logging Evaluation of Trona in Fengcheng Formation of Mahu Sag MAO Rui, ZHAO Lei, SHEN Ziming, LUO Xingping, CHEN Shanhe, FENG Cheng Xinjiang Petroleum Geology    2023, 44 (6): 667-673.   DOI: 10.7657/XJPG20230604 Abstract （723）   HTML （24）    PDF（pc） （1727KB）（643）       Knowledge map    Save The Fengcheng formation of the Mahu sag in the Junggar basin is primarily composed of alkaline lake sediments. A large number of alkaline minerals are developed near the center of the alkaline lake. As a major type in these alkaline minerals, trona is an important industrial resource worthy of development. Currently, the trona intervals are mainly qualitatively evaluated by using the crossplot method, and a quantitative evaluation method is required. Based on core analysis and thin-section identification on alkaline minerals, together with previous research findings, the alkaline minerals in the Fengcheng formation are classified into four categories: trona, shortite; huntite, and searlesite, and their physical properties and impacts on both reservoir properties and oil-bearing property are identified. The influence of trona content on logging responses is analyzed, and a predictive model for trona content is developed by using the deep-to-shallow resistivity ratio. Core data uninvolved in the modeling are used for verifying the predictive model. It is found that the trona content predicted by the model and the trona content measured in the sample are in good agreement, with an average relative error of 5.67%, meeting the requirements for precise mineral content calculations. Finally, based on the logging evaluation results of trona content from eleven wells, the distribution of trona in the Fengcheng formation is clarified. The research results may provide a theoretical and technical support for trona resource evaluation. Table and Figures | Reference | Related Articles | Metrics

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Water Production Mechanism in Tight Sandstone Gas Reservoirs After Fracturing in Linxing Gas Field SHI Xuefeng, YOU Lijun, GE Yan, HU Yunting, MA Litao, WANG Yijun, GUO Sasa Xinjiang Petroleum Geology    2024, 45 (1): 81-87.   DOI: 10.7657/XJPG20240111 Abstract （825）   HTML （9）    PDF（pc） （678KB）（609）       Knowledge map    Save The tight sandstone gas reservoirs in the Linxing gas field，Ordos basin，are key targets for onshore gas development. Due to the structural complexity，reservoir physical properties，and complicated gas-water relationship，most gas wells produce water continuously after fracturing，and their water production rates are very different. Understanding the reasons for irreducible water saturation variation after fracturing is of great significance for formulating effective water control and gas recovery measures to increase well productivity. In this study，representative tight sandstone samples from the Linxing gas field were tested by using the gas displacement method to clarify how reservoir properties，production pressure difference，and fracturing fluid affect irreducible water saturation. The results show that the difference in the irreducible water saturation between matrix and fractures is 13.32%~18.36% for Class Ⅰ reservoirs，28.28%~34.19% for Class Ⅱ reservoirs，and 39.10%~48.15% for Class Ⅲ reservoirs. Hydraulic fractures can significantly improve the water flow capacity of reservoirs，and provide additional water flow pathways. The increased production pressure difference，reduced flow pressure loss and weakened hydrophilic degree are the main mechanisms leading to the weakening capacity of the reservoir in bounding water and water production of gas wells after fracturing. To control water and produce gas efficiently in tight sandstone gas reservoirs with high water cut after fracturing，measures such as controlling fracturing scale，optimizing production systems，and adjusting fracturing additive amount can be implemented，which will help delay the onset of water breakthrough in gas wells and reduce the overall water production. Table and Figures | Reference | Related Articles | Metrics