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01 January 2019, Volume 38 Issue 5 Previous Issue    Next Issue

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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 2017, 38 (5):  1-1.  doi: 10.7657/XJPG20170501 Abstract ( 116 )   PDF (300KB) ( 146 )   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

Triassic Provenance and Its Tectonic Significance in Sikeshu Sag, Junggar Basin ZHU Wena, WU Chaodonga,b, WANG Jialina, CHEN Ronga,b, WU Juna,b, ZHOU Tianqia,b 2017, 38 (5):  1-1.  doi: 10.7657/XJPG20170502 Abstract ( 105 )   PDF (300KB) ( 283 )   Save Permian and Triassic are the key periods for tectonic evolution in Junggar basin, but there are lots of disputes on the understanding of the tectonic evolution. Aiming at Triassic series of Sikeshu sag, the paper performs provenance analysis by combining the data of sedimentary environment, paleocurrent direction, gravel composition, detrital component of sandstone and detrital zircon age of U-Pb, and discusses the tectonic evolution history of the southern margin of Junggar basin during Triassic period. The composite analysis shows that the orogenic belts of North Tianshan Mountains and the northern margin of the central Tianshan Mountains are the major provenances of the upper Cangfanggou group of the Lower Triassic in Sikeshu sag, and the South Tianshan Mountains and the southern margin of Central Tianshan Mountains are the minor provenances. The variations of the provenances during Middle-Late Triassic epochs can be attributed to the subsidence of sedimentary basin resulted from the occurrence of depression in the southern margin of Junggar basin, which was the initiation of Sikeshu sag, indicating that Middle-Late Triassic epochs are the key periods for the down-wraped basin evolution in the southern margin of Junggar basin Related Articles | Metrics

Genesis of Authigenic Chlorite and Its Influence on Reservoir Physical Properties in Conglomerates of Baikouquan Formation, Mahu Sag QU Jianhua1, QIAN Haitao1, LI Peng1, YOU Xincai1, YUAN Rui2 2017, 38 (5):  1-1.  doi: 10.7657/XJPG20170503 Abstract ( 81 )   PDF (300KB) ( 280 )   Save Based on the data of core, cast thin section, SEM, clay mineral analysis by X-ray diffraction and physical property analysis, the paper analyzes the forming mechanism of authigenic chlorite and its influence on reservoir physical properties of the conglomerates in the Lower Triassic Baikouquan formation in Xiazijie fan and Huangyangquan fan of Mahu sag. The study results show that the authigenic chlorite in the conglomerates occurs mainly in 3 types such as grain-coating, pore-lining and pore-filling. The authigenic chlorite was mainly developed in alkaline water environment with high Fe2+ and Mg2+ content and originated from clay mineral transformation, volcanic material alteration and pore water crystallization. The gravels with grain-coating chlorite developed are in point and line contacts, which could improve the ability to resist compaction and mechanical strength of the rocks. The development of pore-lining chlorite restrains the growth of quartz. The authigenic chlorite is in favor of pore preservation in reservoirs. The effective porosity of the conglomerate reservoirs in Baikouquan formation of Mahu sag increases with the increase of the content of authigenic chlorite, and the higher the content of authigenic chlorite, the better the oil bearing property of the reservoir will be Related Articles | Metrics

Mesozoic Formation Water Characteristics and Hydrocarbon Geological Significance in the Hinterland of Junggar Basin GONG Yajun 2017, 38 (5):  1-1.  doi: 10.7657/XJPG20170504 Abstract ( 76 )   PDF (300KB) ( 137 )   Save As a medium for hydrocarbon migration and accumulation, formation water plays an important role in oil and gas entrapment. In order to further understand the relationship between formation water and hydrocarbon accumulation, based on hydrodynamic system classification of Mesozoic formation in the hinterland of Junggar basin, the paper analyzes pressure, salinity, type and oil & gas-bearing properties of the formation water in the hydrodynamic system, and demonstrates geological significance of the formation water by combining with the analyses on formation water origin and its genetic mechanism. The results show that 3 hydrodynamic systems are developed vertically in the Mesozoic strata; the formation water can be divided into 10 subclasses of 3 types. NaHCO3-type formation water is mainly related to surface fresh water, compaction released water of shales and hydrocarbon generation of organic matter; Na2SO4-type formation water mainly originates from infiltration of saline karst water and hydrocarbon generation and expulsion of coal-measure source rocks; CaCl2-type and MgCl2-type formation water are controlled by forward concentration and cation exchange. The differences of hydrocarbons with different formation water types depend on whether the hydrocarbon-bearing fluid is charged, charging sequence and duration and charging degree. For a series of fluid charging during geological processes, the earlier the hydrocarbon-bearing fluid charges， the longer the charging duration and the higher the charging degree is, the higher the hydrocarbon enrichment degree will be Related Articles | Metrics

Architecture of Channel Sand Body in Baodaowan Formation of Aerqingou Section in Southern Margin of Junggar Basin ZHAO Kang1, SHUANG Qi1, WANG Bing2, HUANG Yunfei1, WANG Xin2, DONG Yan2 2017, 38 (5):  1-1.  doi: 10.7657/XJPG20170505 Abstract ( 66 )   PDF (300KB) ( 122 )   Save In order to study the sedimentary characteristics and to classify the architecture of braided channel sand body in Badaowan formation of Aerqingou section in the southern margin of Junggar basin, and guided by theories of sedimentology and reservoir architecture, field outcrop observation and measurement are conducted. In the sand bodies of Badaowan formation, 11 lithofacies are found, boundaries with 6 levels are classified and 4 key elements of architecture are identified on Aerqingou section, based on which a reservoir architecture development model and its distribution patterns are established for the outcrop. The results show that the sand body results from depositional superimposition of 2 stages of braided channel events; 3-level to 6-level boundaries within the sand body can reduce horizontal and vertical connectivities in different extent and increase reservoir heterogeneity. Enhanced outcrop study and using architectural methods to dissect reservoirs can help us better understand reservoir heterogeneity Related Articles | Metrics

Genetic Classification of Sandy Conglomerate Facies and Sedimentary Characteristics of Fan Delta : A Case Study from Upper Wuerhe Formation in District Wuba in Northwestern Margin of Junggar Basin WANG Xiaojing1, LI Weifeng2, DONG Hong1, ZHU Jian1, ZHANG Daiyan1, YIN Shujian3 2017, 38 (5):  1-1.  doi: 10.7657/XJPG20170506 Abstract ( 127 )   PDF (300KB) ( 376 )   Save The upper Wuerhe formation of Upper Permian in District Wuba of Karamay oilfield in the northwestern margin of Junggar basin is a set of terrigenous coarse-grained clastic rocks. The main reservoir of the formation is sandy conglomerate and there are always some disputes on its sedimentary facies: alluvial fan, alluvial fan-fan delta or alluvial fan-nearshore subsea fan-fan delta. Further study on lithofacies will be benefit for accelerating the hydrocarbon exploration and development in the study area. By integrating data of core, rock thin section, lab analysis, mud log and well logging, the paper performs in-depth study on sedimentary characteristics of the formation. The study results show that the sedimentary facies of the upper Wuerhe formation in the study area is not an alluvial fan with its composite deposition system, but a set of typical fan delta depositions including 9 microfacies, i.e., fan channel, debris flow and underwater distributary channel and so on. The paper also defines relationships between lithofacies and sedimentary microfacies. It is considered that the the physical property, oil-bearing property and formation test productivity of tractive-current sandy conglomerate are better than those of gravity-current sandy conglomerate, which could provide geological theory basis for future oil and gas exploration and development in the area Related Articles | Metrics

Sedimentary Characteristics and Model of Outcrop in Jingjingzigou Formation of Southern Margin, Junggar Basin ZHANG Chi, YU Xinghe, LI Shunli, CHEN Hongliang, YANG Zhihao, LI Yalong 2017, 38 (5):  1-1.  doi: 10.7657/XJPG20170507 Abstract ( 107 )   PDF (300KB) ( 479 )   Save To solve the problems that the depositional environment of the Middle Permian Jingjingzigou formation in southern margin of Junggar basin is unclear and its sedimentary model is controversial, starting from 2 outcrop profiles such as Sigonghe and Sigonghe Coal Mine Plant, the paper makes a detailed study on the sedimentary characteristics of the formation, divides the formation into 11 lithofacies and 6 vertical sequences, identifies cyclic base levels including scour surface, lithofacies transition surface and flooding surface, concludes the abrupt change of paleoclimate from humid reducing environment to dry oxidation environment, and establishes a sedimentary model of braided-river delta for Jingjingzigou formation based on combination with typical profile analysis. The study shows that several sets of sandstones and mudstones deposited in the Jingjingzigou formation in the southern margin of Junggar basin, which are dominated by grey color and interbedded with several sets of coal beds. Large amount of debris of plant fossils can be noted in the formation, indicating a humid and warm paleoclimate which was suitable for vegetation growth. The interbedded red-brown sandstone in the middle indicates an abrupt change of the paleoclimate. Braided-river delta is mainly developed in the formation including distributary channel, swamp, interdistributary bay, underwater distributary channel and mouth bar etc. Relatively high sandstone ratio shows a characteristic of “mud coated by sand”. The base level rises continuously due to the influence of regional structures and downward half-cycle is poorly developed under the impact of river channel down-cutting Related Articles | Metrics

Evaluation of Source Rocks and Tight Oil Exploration Potential of Chang-7 Member in Central and Western Ordos Basin SONG Xingpei, LIU Luofu, XU Zhengjian, DOU Wenchao, YANG Yueshu, LIU Xiaoxiang 2017, 38 (5):  1-1.  doi: 10.7657/XJPG20170508 Abstract ( 67 )   PDF (300KB) ( 197 )   Save There is lack of profound study on the source rocks in Chang-7 member of Yanchang formation in the central and western Ordos basin, which restricts the oil and gas exploration process in the area. In order to clarify hydrocarbon generation conditions of the source rocks in Chang-7 member, the paper makes a systematic analysis on distribution and geochemical characteristics of Chang-7 source rocks in the area based on enormous amounts of actual data and previous research results, predicts favorable areas for oil and gas exploration and provides basis for tight oil exploration in Yanchang formation in the study area. The results show that the depocenters of the source rocks in the study area were mainly located in Jiyuan, Gengwan, Eastern Huan County, Baibo and Zhifang area during the deposition of Chang-7 member. The dark shales with large average cumulative thickness in Chang-7 member are characterized by good organic matter type, high organic matter abundance and high thermal evolution degree (indicating a stage of hydrocarbon generation), which belong to typical high-quality lacustrine source rocks and are major source rocks of Yanchang formation in the area. 6 favorable exploration areas are determined in the study area, including the western Youfangzhuang area to the south of Dingbian, the area to the east of Jiyuan, the area to the south of Tiebiancheng, northeastern Tiebiancheng area, northeastern Huan county and the area to the south of Baibo Related Articles | Metrics

Lower Limits of Physical Properties of Glutenite Reservoir in Lower Section of the 4th Member of Shahejie Formation in Steep Slope Zone of Northern Dongying Sag GAO Yang 2017, 38 (5):  1-1.  doi: 10.7657/XJPG20170509 Abstract ( 59 )   PDF (300KB) ( 112 )   Save Glutenite reservoir in the lower section of the 4th member of Shahejie formation in the northern steep slop zone of Dongying sag is characterized by strong heterogeneity, complex lithology, large variation of reservoir burial depth and complicated oil and gas phases. In addition, due to the lack of drilling and single-layer formation test data, it is difficult to determine the lower limits of physical properties of the effective reservoir. Base on methods of formation test, oil-bearing occurrence in cores, minimum flow pore throat radius and positive & negative cumulative method, the lower limits of porosity and permeability of the glutenite reservoir with different fluids and at different burial depth are determined. The research results show that the lower limits of porosity and permeability for reservoirs at the burial depth of 3000~4000 m are 6% and 1.0mD, respectively; those for condensate reservoirs at the burial depth of 4000~4500 m are 4% and 0.2mD; and those for gas reservoirs with the burial depth larger than 4500 m are 3% and 0.1mD. With the increase of burial depth, the properties of reservoir fluids change, and pore structures and reservoir space types change, too, which results in the gradual decline of the lower limits of reservoir physical properties Related Articles | Metrics

Comprehensive Dissection of Meandering-River Sedimentary System in Qinhuangdao 32-6 Oilfield, Bohai Bay Basin MA Pinghua1, HUO Mengying1, HE Jun1, SHAO Xianjie1, HUO Chunliang2, WU Ning1 2017, 38 (5):  1-1.  doi: 10.7657/XJPG20170510 Abstract ( 71 )   PDF (300KB) ( 132 )   Save Because the lateral oscillation amplitude of a meandering river is large, channel deposits are in stagger arrangement and there are no isochronous surface and stable marker bed in the sedimentary system, which leads to difficulties for sand body tracing. The use of well logging-seismic joint inversion technology can improve the resolution of sand body in point bars. Based on the establishment of lithofacies, logging facies and seismic facies and making full use of the characteristics of cores, high vertical resolution of logging curves and good lateral continuity of seismic signals, the accuracies of vertical classification and lateral correlation for channel units of different periods are improved. Abandoned river channel, point bar, flood plain and crevasse splay are identified accurately by overlapping sand body thickness contours, logging facies and seismic wave impedance slices. Based on the statistics of modern meandering river and outcrop data at home and abroad, the paper establishes relationships among geometrical parameters of point bars, puts forward methods to identify lateral accretion body, accretion surface and accretion bed of point bars and a method for internal architecture study, which provides reliable constraint conditions for accurate geological model establishment Related Articles | Metrics

Quantitative Heterogeneity Evaluation of Heavy Oil Reservoirs in Wellblock Zhong-18 of Fengcheng Oilfield, Xinjiang LIN Botao1, LIU Xing1, CHEN Sen2, JIN Yan1, PAN Jingjun2 2017, 38 (5):  1-1.  doi: 10.7657/XJPG20170511 Abstract ( 68 )   PDF (300KB) ( 197 )   Save Muddy interbeds are extremely developed and widely distributed in the terrestrial heavy oil reservoirs in Fengcheng oilfield, Xinjiang. The muddy interbeds exhibit serious heterogeneous and discontinuous distribution with distinct differences between intervals, which significantly impacts the effective development of the heavy oil reservoirs by SAGD technology. In order to evaluate the quality and reconstruction effect of the reservoirs, the reservoir heterogeneity caused by the muddy interbeds needs to be quantitatively analyzed. By using the Lorenz curve method, the paper establishes an evaluation model to characterize the muddy interbed distribution in oil sands; and presents several concepts about geometrical heterogeneity coefficient, numerical heterogeneity coefficient and composite heterogeneity coefficient and their calculation methods. With this method, the permeability profiles of 3 SAGD wells are evaluated in Wellblock Zhong-18 of Fengcheng oilfield, and their correlations with the recovery after 14 years of stable production which is predicted by CMG numerical simulation software are analyzed. The results show that the method can distinguish the heterogeneity differences between different profiles and the composite heterogeneity coefficient exhibits a good negative correlation with the recovery, which could guide block optimization for SAGD and reservoir reconstruction effect evaluation Related Articles | Metrics

Thermal Simulation Experiment on Asphaltene in Biodegraded Heavy Oil LI Erting1, CHEN Jun1,YU Shuang2, ZHOU Ni1, MA Wanyun1, WANG Yi1, LONG Xinman1 2017, 38 (5):  1-1.  doi: 10.7657/XJPG20170512 Abstract ( 54 )   PDF (300KB) ( 202 )   Save The paper analyzes and compares the biomarkers in the products from asphaltene thermal simulation at different temperatures in normal crude oil and heavy oil suffered from serious biodegradation in the northwestern margin of Junggar basin. The results show that relatively ideal temperature for the thermal simulation is 300℃, at which biomarker composition distribution of the products from the asphaltene thermal simulation of heavy oil is in accordance with that of normal crude oil. The biomarker in the simulation products of the heavy oil has complete compositions, indicating that it didn’t suffer from biodegradation and can be used to do oil source analysis for seriously biodegraded oil, which is featured with relatively high Pr/nC17 and Ph/nC18（0.66~0.71 and 1.01~1.21, respectively), relatively low Pr/Ph （1.15~1.21) and relatively high gammacerane index (0.30~0.41), indicating a weak reducing-reducing and brackish water-saline water depositional environment of organic parent materials; a C20＞C21＞C23 distribution pattern of tricyclic terpane and C23 tricyclic terpane/(C30 hopane + C23 tricyclic terpane) of 0.46~0.49; and extremely low content of Ts and C29Ts, showing that it is almost the same to the biomarker in the typical source rocks of Fengcheng formation Related Articles | Metrics

Calculation Methods of Water Influx in Gas Reservoirs with Aquifers YU Qingyan1, MU Zhenbao2, LIU Pengcheng1, LI Yong3, XIA Jing3, LI Baozhu3 2017, 38 (5):  1-1.  doi: 10.7657/XJPG20170513 Abstract ( 131 )   PDF (300KB) ( 189 )   Save During the development of gas reservoirs with aquifers, reservoir pressure decreases gradually with gas production, and edge and bottom water will cone into gas reservoirs. In the early stage of water invasion, waterflood front is relatively far from bottom hole. If the aquifer is distributed uniformly, the waterflood front can advance stably, at the moment the driving effect of aquifer can replenish energy for gas reservoirs, allowing the average gas reservoir pressure drop to slow down and gas production to be maintained. In the middle-late stage of water invasion, gas wells will be watered out rapidly and wellbore liquid loading will seriously impact gas production. Therefore, the analysis of water invasion performance and obtaining of water invasion time, aquifer size and water influx at each time point are of great significance for developing gas reservoirs with aquifer. Iterative solution is made by combining material balance equation for water-drive gas reservoir and pseudo-steady state water invasion equation. Finally, by using C# programming language, parameters including dynamic reserves of gas reservoir, aquifer size, and water invasion rate and cumulative water influx at each time point can be determined on the basis of production data matching in gas wells. The established numerical simulation model for gas reservoirs verifies that the method is reliable and applicable in field, and can get results rapidly with small error. The numerical simulation results directly show the validity of the water influx evaluation Related Articles | Metrics

Reasons of High Water Yield and Reservoir Reformation in Horizontal Wells in Shiguhao Area of Dongsheng Gas Field WANG Donghuia, CAO Shaohea, GUI Pingjuna, ZHANG Yongchunb 2017, 38 (5):  1-1.  doi: 10.7657/XJPG20170514 Abstract ( 55 )   PDF (300KB) ( 166 )   Save High water yield occurs during production test in some horizontal wells in Shiguhao area of Dongsheng gas field, which impacts the productivity construction in the gas field. In order to define gas reservoir type and hydrocarbon distribution, the paper conducts well selection for test by combining with single layer production characteristics, establishes well-logging standards for gas zone and aquifer identification for the Lower Shihezi formation on the basis of crossplot chart analysis and determines the gas and water distribution in He1 and He 2 section. After analyzing the relationship between construction parameter and hydraulic fracture height, it is considered that construction displacement has a significant impact on hydraulic fracture height. The relationship between fracturing scale and hydraulic fracture height in gas reservoirs is established and fracture heights under different fracturing scales can be effectively determined. Combined with electrical parameter, microfracture distribution, fracture height and thickness of reservoir and interlayer etc., 3 reasons causing the high water yield are identified in horizontal wells and a “one measure in one well ”reservoir reformation countermeasure is put forward Related Articles | Metrics

Energy-Saving Effect of Fireflooding Development in Hongqian Pilot Test Area of Karamay Oilfield LIANG Jianjun1, JI Ling1, JIANG Xiping2, CHEN Long1 2017, 38 (5):  1-1.  doi: 10.7657/XJPG20170515 Abstract ( 45 )   PDF (300KB) ( 95 )   Save Based on the research of fireflooding production process in the Hongqian pilot test area of Karamay oilfield, Junggar basin, the paper divides energy consumption system of fireflooding and analyzes main factors influencing energy consumption for each system. The research result shows that the energy consumption of fireflooding mainly comes from air injection system, among which energy consumption of air compressor accounts for the largest proportion. Energy consumptions of fireflooding and steamflooding are compared with each other under the same oil production conditions, and it is considered that fireflooding has obvious advantages on energy consumption, and can be an effective alternative technology for successive oilfield development when oil-steam ratio of reservoir is low and energy consumption is large during thermal recovery by steam injection. Because the water cut of the produced liquid during fireflooding is low, the treatment has obvious advantages compared with steam injection Related Articles | Metrics

Microscopic Damage Mechanism of Asphaltene Deposition on Cores during CO2 Flooding WANG Chen1,2, LI Tiantai2, GAO Hui2, ZHAO Jinsheng2, GAO Yuan3, DOU Liangbin2 2017, 38 (5):  1-1.  doi: 10.7657/XJPG20170516 Abstract ( 74 )   PDF (300KB) ( 250 )   Save In order to study microscopic damage mechanism of asphaltene deposition on reservoirs with different permeabilities during CO2 flooding, cores with high, medium and low permeabilities are selected for indoor CO2 flooding experiments and plugging degree of pore throat in cores are analyzed quantitatively by using NMR technology. The experimental results show that the deposition rate of asphaltene during miscible phase stage is obviously higher than that during immiscible phase stage, and the deposition rates are basically same in the cores with different permeabilities; permeability damage rate is positively correlated with the asphaltene deposition rate and the larger the core permeability, the smaller the permeability damage rate; the pore throats in low-permeability cores are blocked seriously with the plugging rate of relatively small pore throats (0.01~1 ms) reaching 38.19%, the plugging rate of relatively small pore throats in high-permeability cores is only 9.59%, which is significantly lower than the previous one Related Articles | Metrics

Water Cut Rising Law of Low-Amplitude Heavy Oil Reservoirs with Bottom Water in Horizontal Wells OUYANG Yuwei, HU Yong, ZHANG Yunlai, ZHANG Wei, XU Yanan 2017, 38 (5):  1-1.  doi: 10.7657/XJPG20170517 Abstract ( 59 )   PDF (300KB) ( 94 )   Save To determine water cut rising law of low-amplitude heavy oil reservoirs with bottom water in horizontal wells, the paper considers dynamic and static parameters, uses a comprehensive method combining numerical simulation, waterflooding type curves with production performance analysis, and summarizes the order of influences of different parameter on water cut variations in reservoirs with bottom water in horizontal wells. Linear regression equations related to each parameter are obtained and a chart showing water cut rising in horizontal wells is established. Based on the comparison of production performance data in horizontal wells with that of Q oilfield in the middle of Bohai Sea, it is considered that the method has relatively high prediction accuracy, which could provide basis for production system adjustment in horizontal wells, meanwhile provide theoretical basis for horizontal well production allocation at the early stage Related Articles | Metrics

pplication of SAGD Technology with Fishbone Steam-Injection Horizontal Well in Super Heavy Oil Reservoirs ZHAO Ruia, LUO Chihuia, CHEN Heqinga, ZHEN Guinanb, GAN Shanshana 2017, 38 (5):  1-1.  doi: 10.7657/XJPG20170518 Abstract ( 97 )   PDF (300KB) ( 201 )   Save In order to accelerate the expansion of steam chamber and to reduce the impact of interlayers during SAGD development for heterogeneous heavy oil reservoirs, a steam injection method with fishbone horizontal well is put forward. Taking Wellblock A of Fengcheng oilfield as an example, main factors influencing production effects of SAGD technology with fishbone steam-injection horizontal well are analyzed and branch shapes and key injection-production parameters are optimized by using numerical simulation technique. The study results show that horizontal and vertical displacements of branches are positively correlated with production effects of well groups, and the production effect of staggered branch distribution is better than those of symmetry and same-side branch distributions. When interlayers exist above fishbone steam-injection horizontal wells, the optimum production effect can be gained when the branches go across the interlayers. The actual application shows that both initial daily oil production and oil/ steam ratio of the fishbone steam-injection horizontal wells are higher than those of horizontal wells without a branch under the same conditions. The production method has certain advantages and can be guidance for similar reservoir development Related Articles | Metrics

Identification Method for Low-Contrast Pay Zones by Well-Logging Analysis:A Case Study of Dongying Formation in Block Nanpu 2-1 of Jidong Oilfield, Baihai Bay Basin ZHANG Ying1, WANG Teng2, XU Bo1, ZHANG Jie1, QU Lili1 2017, 38 (5):  1-1.  doi: 10.7657/XJPG20170519 Abstract ( 75 )   PDF (300KB) ( 188 )   Save Regarding the problems that a large number of low-contrast pay zones exist in Dongying formation of the Block Nanpu 2-1 in Jidong oilfield, Bohai Bay basin and conventional logging methods cannot be used to accurately evaluate oil-bearing properties of reservoirs, the paper introduces the natural gamma relative value and apparent formation water resistivity as valid parameters, uses logging chart to eliminate influences of lithology and water on electrical properties, applies probabilistic neural network (PNN) method to enhance logging identification accuracy, which could solve the contradiction between electrical and oil-bearing properties, and finally develops an evaluation technology taking amplifying electrical characteristics as the core. The research results have guiding significance for low-contrast pay zone identification by well-logging analysis Related Articles | Metrics

Methods of Production Data Analysis for Wells with Vertical Fractures in Low-Permeability Tight Gas Reservoirs CHENG Minhua1, LU Cheng2,3, WANG Junlei1, YUAN He1, WANG Xiaodong3 2017, 38 (5):  1-1.  doi: 10.7657/XJPG20170520 Abstract ( 53 )   PDF (300KB) ( 195 )   Save To further improve the accuracy and reliability of production data analysis for wells with vertical fractures in low-permeability tight gas reservoirs, the paper uses a point-sink function model for vertical fractures, and establishes an expression of side wall pressure with uniform flows in Laplace space, based on which typical curve charts of Blasingame-mode production data analysis are mapped through numerical inversion. A rapid and simple chart matching method is obtained after the characteristics of each flowing stage on the charts are analyzed. Through production data matching, effective parameters such as well control reserves, permeability, single well drainage area and radius, and fracture half-length etc. are gained, which can be used to evaluate single-well fracturing effect rapidly and effectively Related Articles | Metrics

Gas and Water Distribution Patterns of Callovian-Oxfordian Gas Reservoirs in Western Block B of the Right Bank, Amu Darya Basin LI Hanyun1,2, WANG Xingzhi2, LIU Yong1, XU Jianting1, YANG Xiaogang3 2017, 38 (5):  1-1.  doi: 10.7657/XJPG20170521 Abstract ( 52 )   PDF (300KB) ( 120 )   Save The western Block B of Amu Darya right bank has great potential for natural gas development. But the current exploration degree is relatively low, and gas and water distribution is not clear, which restricts the additional well allocation and follow-up development plan making. Based on the integrated use of logging and test results, the paper analyzes the relationship between gas and water in gas reservoirs, establishes a gas-water identification standard for the early exploration stage in the study area. It is considered that a pattern of “gas above and water below” exists in single wells vertically, but several gas-water systems are found regionally and there is no unified gas-water contact. The paper presents 3 gas-water distribution patterns for gas fields in western Block B of the right bank of Amu Darya, namely structural laminar edge-water gas reservoir, structural laminar bottom-water gas reservoir and structural lithological edge-water gas reservoir; and determines the planar distribution characteristics of each pattern, which could provide references for the study on gas-water distribution in multi-trap, complicated gas reservoirs in the similar carbonate rocks Related Articles | Metrics