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01 February 2007, Volume 28 Issue 1 Previous Issue    Next Issue

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Hydrocarbon Accumulation Conditions and Advantageous Exploration Targets in Foreland Basins of Central-Western China JIANG Fu-jie, JIANG Zhen-xue, PANG Xiong-qi, LIN Shi-guo, ZHU Hou-qin, LI Hong-yi 2007, 28 (1):  1-6.  Abstract ( 104 )   PDF (275KB) ( 211 )   Save The foreland basins in central and western regions of China are rich in oil and gas resources, but the discovery rate of resources is only about 9.3%, so it is necessary to carry out systematic analysis of the hydrocarbon accumulation conditions for guiding the oil-gas exploration in the regions. On the basis of comprehensive analyses on hydrocarbon accumulation conditions in the four representative foreland basins, Kuqa basin, southern Junggar basin, western Sichuan basin and northern margin of Qaidam basin, some conclusions are made as follows: The foreland basins in central and western regions of China are characterized by multi-set source rocks dominated by coal measure; heterogeneous reservoirs; multiple and sealing cap rock; anticline traps; unblocked transport system composed of fault, unconformity and highly permeable sand body; and poor conservative conditions, etc. According to these results combined with exploration practice, four favorable exploration zones are selected, these are the integrated anticline traps below the Tertiary gypsum halite, gypsum mudstone in Kuqa foreland thrust belts, the second and the third row structural belts in southern Junggar foreland thrust belt, the unconventional natural gas pools in the Yanshan palaeohigh in north and south of western Sichuan basin, the gentle fold structural belt in central Sichuan basin and the deep depression in Sichuan basin, and the cold lake and Nanbaxian structural belt in northern margin of Qaidam basin. References | Related Articles | Metrics

Quantitative Prediction of Ordovician Petroleum Resources in Tahe Oilfield ZHOU Zong-ying, HE Hong 2007, 28 (1):  7-10.  Abstract ( 77 )   PDF (166KB) ( 238 )   Save In view of the petroleum geologic conditions and exploration degree of Ordovician in Tahe oilfield, three different methods such as pool size sequence, resources area abundance and geologic factor regression are selected for prediction/estimation of its potential resources. The study shows that the results given by these three methods are quite consistent and have good comparability. The predicted petroleum resources in place of Ordovician in Tahe oilfield amount to about 1.414×109 t, which provide the geological basis for oil-gas exploration planning and preparing the mid-and long-term development goals in this area. References | Related Articles | Metrics

Structural Activity of Wuxia Fault Belt in Junggar Basin QIU Yi-bo, ZHA Ming, LI Zhen-hua, GAO Wei-hong 2007, 28 (1):  11-14.  Abstract ( 101 )   PDF (306KB) ( 203 )   Save Wuxia fault belt in the eastern part of northwestern margin of Junggar basin is an important part in the thrust belt of the northwestern margin. There existed multiple unconformities owing to multistage structural activities. However, the large-scale erosions in the uplift areas of the fault belt and the surrounding margins allow the determination of the fault active periods to be difficult. This paper analyzes the sedimentation and the occurrence of the strata in Wuxia area and suggests that Wuxia area underwent the development of foreland basin of Early Permian, the overthrust nappe of Late Permian, the strong structural uplift of Late Triassic, the weak structural activity of Late Jurassic and the structural shape of Cretaceous followed by finally forming the configuration nowadays. References | Related Articles | Metrics

Ordovician Palaeogeomorphology and Reservoir-Controlled Process in Tazhong Area, Tarim Basin WANG Hong-yu, FAN Tai-liang, GAO Zhi-qian, XUE Yan-mei 2007, 28 (1):  15-19.  Abstract ( 90 )   PDF (248KB) ( 228 )   Save The Ordovician in Tazhong area is characterized by large buried depth and stable lateral distribution before the Middlle-Lower Ordovician underwent erosion. By means of seismic stratigraphy, thickness tendency analysis and Ro data, the palaeogeomorphology in middle period of Caledonian tectonic movement in this area is well described as follows: Tazhong uplift is an ellipse shape region around No.2 structural belt with smooth topography and undeveloped local structures; existing slope break zone from surrounding sags to major uplift, and gradual variation of relief by features of sag→slope→platform margin break zone→inner-platform topographic low and ramp→ swell. The Upper Ordovician reef flat mainly distributed in the platform margin break zone and the inner-platform swell ramp zone, with feature of shifting with the platform margin migration. Study shows that the palaeogeomorphology is of remarkable effect on controlling the distribution, vertical evolution and lateral migration of reef flat reservoir body. It is predicted that there existed the platform margin facies in Mid-Late Caledonian tectonic movement in the area between TB-2 well and Z-3 well in southern Tazhong area, meaning that this area has the favorable conditions for biobermal reservoir development. References | Related Articles | Metrics

Characteristics and Types of Sedimentary Facies of Cretaceous in Yinmaili Area LIU Yong, WANG Zhen-yu, MA Qing 2007, 28 (1):  20-24.  Abstract ( 79 )   PDF (246KB) ( 194 )   Save The structural uplift is developed in Yinmaili area. According to available data of Cretaceous and the regional ancient relief in Yinmaili area, four types of sedimentary facies are identified, which include the alluvial facies, fan-delta facies, lacustrine facies and delta facies. Their lithologic features, sedimentary structures and vertical evolution sequences are analyzed in detail. For questionable existence of Yageliemu formation in this studied area, this paper indicates that original classification about the glutenite stratum into Jurassic should belong to bottom glutenite member (i.e. Yageliemu formation) by the strata contact relations. This means that in Yinmaili area the center of sedimentation and subsidence underwent multi-transportation, which is the important reason for the fact that large-scale variation and migration of sediments or sedimentary sand bodies occurred in this area. References | Related Articles | Metrics

Immature Crude Oil in Qintong Sag: Kerogen Character istics and Oil Sources Analysis HU Ying, ZHANG Zhi-huan, LUO Wei-feng 2007, 28 (1):  25-28.  Abstract ( 77 )   PDF (209KB) ( 199 )   Save The biomarker assemblage of immature crude oil from Qintong sag shows its multi-source complex characteristics. Higher plant and thallogen microbes are the most important hydrocarbon-generating kerogen of the oil, accounting for 40%~70% and 12%~40% of the total amount of hydrocarbon generation, respectively. Meanwhile, according to the source rocks in different horizons and the biomarker geochemistry, the main oil source of immature crude oil in this area is analyzed. References | Related Articles | Metrics

Geochemical Characteristics and Significance of Aromatic Hydrocarbon in Oil and Gas WANG Chuan-yuan, DU Jian-guo, DUAN Yi, ZHOU Xiao-cheng, ZHENG Chao-yang, WU Bao-xiang 2007, 28 (1):  29-32.  Abstract ( 200 )   PDF (132KB) ( 664 )   Save This paper reviews the application and advances of aromatic hydrocarbon biomarker in petroleum exploration and development, such as depositional environment, input of organic matter, migration, oil source correlation and thermal maturity. The result indicates that alkylnaphthalene and aromatic sulfur compounds are indicative of depositional environment and type of organic matter. Fluoranthene, perylene, pyrene benzo-pyrene and benzopyrene have been proposed as the input of terrigenous higher plant. Methylnaphthalene ratio and Methylphenanthrene index increase with the thermal maturity. The relative distribution of dibenzothiophene is well used for maturity assessment. The ratios of perylene to benzofluoranthene and perylene to benzo (e) pyrene are an effective index of thermal maturity. It is determined that the contents and distribution of pyrrolic compounds and dibenzothiophene are controlled by oil fraction during migration, which has potential significance in evaluating the oil migration and reservoir filling direction. The component of aromatic hydrocarbon in sediment is very complicated, so that great efforts should be made to identify them with more advanced apparatus and improve some biomarker index by experiments and practices. References | Related Articles | Metrics

Determination of Hydrocarbon Accumulation Stages in Hinterland Area of Junggar Basin WANG Bi-wei, CHEN Hong-han, SONG Guo-qi 2007, 28 (1):  33-35.  Abstract ( 72 )   PDF (137KB) ( 215 )   Save Three source sags located in the hinterland area of Junggar basin are the western Pen-1 well sag, Changji sag and northern Dongdaohaizi sag, in which there exist two sets of hydrocarbon source rocks (Permian and Jurassic) . They are characterized by the fact that the same set of source rocks in different sags is of different oil thresholds; the different source rocks in the same source sag are of different oil thresholds, too. The fact means that there should be multi-source and multi-stage hydrocarbon supplies/charging in this area, and the four times of tectonic movements (Late Hercynian, Indo-Sinian, Yanshan and Himalayan movements) resulted in the multi-stage hydrocarbon migrations. This paper detects 61 fluid inclusion samples gathered from 4 wells in the hinterland area, including the homogeneous temperatures for fluid inclusions of each stage, the salinities for aqueous inclusions and the fluorescence colors for hydrocarbon inclusions. The result indicates that there might be four times of oil charging events in this hinterland area with the homogeneous temperatures of hydrocarbon inclusions by 29.8～57.8℃, 74.6～90.7℃, 107.4～117.3℃, 135.3～145.8℃, and those of corresponding coexisting aqueous inclusions by 65～80℃, 80～100℃, 100～120℃ and 135～150℃, respectively. References | Related Articles | Metrics

Genetic Potential of Goal-Measure Source Rocks of Lower Cretaceous in Jixi Basin FAN Fu, GAO Fu-hong, GAO Hong-mei 2007, 28 (1):  36-39.  Abstract ( 68 )   PDF (224KB) ( 180 )   Save The Lower Cretaceous deposits are the most important source rocks in Jixi basin of Heilongjiang province. The types of source rocks include black mudstone, coal and carbonaceous mudstone. The organic lithology, the abundance of organic matter, the maturity and the type of source rock are discussed by the methods for organic geochemical analysis. The results show that the organic micro-component of the source rocks is dominated by exinite, with high content of vitrinite in coal and carbonaceous mudstone; the values of organic carbon, IH and S1+S2 reflect that the source rock ranks medium-good one; the organic matter belongs to Type-III kerogen, partly to Type-IIB; the vitrinite reflectance ranges from 0.5% to 1.1%. According to the hydrocarbon-generating mode of Type-III kerogen, the source rocks would be just in the climax of generating liquid hydrocarbon, with oil-gas generating potentials. Also, the good comparison with typical coal-formed oil basins such as Gippsland basin and Tuha basin indicates that Jixi basin is of very good prospect for petroleum exploration. References | Related Articles | Metrics

Geochemical Characteristics of Crude Oils in Mid-Shallow Layer of Wangfu Sag and Adjacent Areas, Songliao Basin JIANG Xing-chao, WANG Tie-guan, FENG Zi-hui, CHEN Jian-fa, WANG Jie, LI Min, WANG Xue 2007, 28 (1):  40-43.  Abstract ( 72 )   PDF (187KB) ( 193 )   Save The group composition, light hydrocarbon, chain alkane, sterane, hopane and stable carbon isotope are analyzed in geochemical characteristics. Study shows that the crude oils from Fuyu-Yangdachengzi zone belong to the same oil source, which could further be divided into three groups such as immature oil (A) , low-middle mature oil (B) and middle mature oil (C) . Type A is found in Wells Chang-20, San-403 and Wu-204 which are located at the highs of palaeo-and present-structure; Type C in Well Shuang-32 located at Wangfu sag, and Type B is distributed in rest areas. References | Related Articles | Metrics

Seismite Feature and Its Reservoir Quality of Shahejie Formation of Paleogene in Jiyang Depression GONG Li-qing, YANG Jian-ping 2007, 28 (1):  44-47.  Abstract ( 73 )   PDF (402KB) ( 205 )   Save Based on core observation, thin section and imaging logging analyses, seismite is recognized in the upper part of Member 4 and Member 3 of Shahejie formation of Paleogene in Jiyang depression. Such a rock features soft sediment deformation structures, including liquefied sand and shale veins, liquefied convolute lamination, step microfault, pillow and ball structures, beaded structure, carbonate micrite vein, autoclastic brecciated structure and pseudonodule, etc. Study shows that sedimentary period of Member 4-Member 3 of Shahejie formation is the intense activity period of the basin boundary fault. The obvious effect of seismism on hydrocarbon reservoir quality greatly improves the reservoir permeability whereas the improved porosity is seldom found. It is concluded that Seismite, especially the shattered rock and seismic-clastic breccia are as potential reservoir rocks. This provides new areas for petroleum exploration and development in the near future here. References | Related Articles | Metrics

The Origin of Sublacustrine Fan and Its Significance for Exploration in Northern Chexi Sub-Sag, Jiyang Depression FAN Zhen-feng 2007, 28 (1):  48-50.  Abstract ( 96 )   PDF (180KB) ( 368 )   Save The sublacustrine fan, as an important deposit in actic region of northern Chexi sub-sag, is characterized with both source and reservoir in it and favorable hydrocarbon accumulation conditions. According to the difference of the genetic mechanism, it is further divided into the slump turbidite fan and the deep-water turbidite fan for they have some differences in seismic profile, depositional character and space distribution. It is suggested that this fan is of good reservoir quality and oil-bearing property due to the effect of the profile structure and the abnormal high pressure fluid compartment, thus having higher values for petroleum exploration. References | Related Articles | Metrics

Analysis of Hydrocarbon Accumulation in West Slope of Mobei-Mosuowan Swell in Junggar Basin ZHOU Wen-quan, WANG Ling, JIANG Yong-jun, MAO Xin-jun, WU Bao-cheng 2007, 28 (1):  51-53.  Abstract ( 103 )   PDF (155KB) ( 199 )   Save The west slope in Mobei-Mosuowan swell in Junggar basin lies chronically in the target area of oil-gas migration. From the north to the south of this slope, Mobei field, Mosuowan field and Moxizhuang oil field have been found. It is one of the oil-enriched structural belts in the hinterland part of Junggar basin, in which the reservoirs are all distributed along the swell side with arcuate and beaded configuration and controlled by faults, structures and deposition. However, these reservoirs with complex distribution are still of particularity and regularity. This paper analyzes and summarizes the regularity of hydrocarbon accumulation in this area for further exploration here in the future. References | Related Articles | Metrics

Relationship Between Chemical Characteristic of Formation Water and Hydrocarbon Accumulation in Hinterland of Junggar Basin LIU Gui-feng, WANG Li, LI Chun-tao, XIE Shu, JIA Guo-lan, ZHANG Li 2007, 28 (1):  54-56.  Abstract ( 76 )   PDF (129KB) ( 334 )   Save Generation, migration, accumulation, preservation and dispersion of hydrocarbon are always associated with or accompanied by formation water. The moving formation water acts as the driving force and the carrier for oil-gas migration, accumulation and dispersion, and its chemical compositions can directly or indirectly reflect the environments and conditions of hydrocarbon occurrence. The movements of formation water and hydrocarbon are of interdependent and inter-restricted relationship. This paper studies the evolution of oil, gas and water in hinterland of Junggar basin from point of view of hydrogeology, analyzes the mutual action among them and the effect of formation water on the formation and distribution of oil-gas reservoirs, including applying some ions and characteristic factors of formation water to reflect the closed relations among the preservation conditions of the oil and gas, the closing degree of reservoirs and the oil-gas migration for the purpose of searching for favorable oil-gas accumulation zones by the varied features of formation water. It is suggested that study of hydrogeology of field water from different areas and different horizons is also a method for exploring oil-gas reservoirs, which can provide essential basis for the oil and/or gas prospect evaluation in this basin. References | Related Articles | Metrics

Relationship Between Abnormal Pressure and Hydrocarbon Accumulation in Ying'er Sag, Jiudong Basin KOU Ke-peng, LI Yong-min, LIU Guang-di 2007, 28 (1):  57-59.  Abstract ( 82 )   PDF (217KB) ( 213 )   Save Ying'er sag in Jiudong basin is characterized by well developed abnormal pressure environment. The distinct geologic characteristic is studied and the 3D abnormal pressure field is established using available sonic logging data and seismic impedance information of Ying'er sag. The feature of the fluid compartment is analyzed. In view of the relations between petroleum distribution and vertical abnormal pressure belt as well as the fluid potential and the petroleum migration and accumulation, the relationship between abnormal pressure and hydrocarbon accumulation is investigated and the favorable targets for petroleum exploration are given. References | Related Articles | Metrics

Magaspore Assemblage of Westphalian Stage of Late Carboniferous in Tazhong Area, Tarim Basin LUO Zheng-jiang, WANG Rui, CHENG Xian-sheng, Aliya, YANG Ji-duan 2007, 28 (1):  60-63.  Abstract ( 75 )   PDF (256KB) ( 168 )   Save Through a study of Late Carboniferous megaspores from Well M-1 in Tazhong area of Tarim basin, the megaspore assemblage of Westphalian stage of Late Carboniferous megaspore assemblage is established and the comparison of this megaspore assemblage is made with those in corresponding horizons at home and abroad such as Benxi and Taiyuan formations in Hebei province, Jingyuan formation in Gansu, Yanghugou formation in Ningxia as well as Sharl-Luolin area in France. The geologic age of the horizon where the assemblage lies is determined to be Westphalian stage of Late Carboniferous.This paper first reports the late Carboniferous megaspore assemblage in Tazhong area, which is of great significance for the biostratigraphic studies and the petroleum exploration and research in Tarim basin. References | Related Articles | Metrics

Stratigraphic and Environmental Significance of Ostracod Cypridea (Pseudocypridina) Gigantea ZHENG Xiu-liang, SHANG Hua 2007, 28 (1):  64-66.  Abstract ( 83 )   PDF (99KB) ( 251 )   Save Cypridea (Pseudocypridina) gigantea of ostracods is regarded as the important member of Late Cretaceous in Junggar basin. It is an ostracod of the mid-late epoch of Late Cretaceous, corresponding to Campania-Maestrichian epoch, widespread in Upper Cretaceous in China. It can be as a marker member of Late Cretaceous for its broad distribution in geography, but short duration in geologic period and well used for strata classification and correlation. From well-developed red layer of Late Cretaceous in Junggar basin, with drier climate, oxidized and evaporated environment, fewer bio-fossils at that time. The existence of ostracod indicates a little fresh and shallow water environment like lake, marsh, pond, river, etc., with low salinity, mostly being river-shallow lake environment in Late Cretaceous of Junggar basin. References | Related Articles | Metrics

Upper Cretaceous Sporopollen Assemblage and Significance of Ziniquanzi Formation in Southern Margin of Junggar Basin SHI Tian-ming, ZHOU Chun-mei, GU Xin-yuan, HE Zhuo-sheng 2007, 28 (1):  67-71.  Abstract ( 86 )   PDF (276KB) ( 270 )   Save A sporopollen assemblage Schizaeoisporites-Classopollis-Yenjiapollis discovered from the mid-lower part of Ziniquanzi formation in southern margin of Junggar basin is reported. According to the characteristics and the correlation results, the geologic era of this sporopollen assemblage is dated as Mid-Late stage (or Early Senonian) of Late Cretaceous. This discovery supplies a gap for absence of sporopollen assemblage of Late Cretaceous in northern Xinjiang, providing significant data or proof for the studies of Late Cretaceous micropaleo-flora in Junggar basin and even in China. From the particularity of this sporopollen assemblage, northern Xinjiang should be classified as arid palynofloral region in northwestern China. References | Related Articles | Metrics

Prediction of Block Fracture Using Nonlinear Deformation—An example of Block Min 15-18 in Jinhu Sag MA Xin-ben 2007, 28 (1):  72-74.  Abstract ( 66 )   PDF (139KB) ( 172 )   Save Nonlinear deformation can be used to separate from strain and rotation in process of deformation by means of its method of sum resolution, set up displacement function, calculate mean rotation angle, a representative value of the rotation and show the growth level and the extension direction of the structural fractures by the angle's changes in plane. In Block Min 15-18 located in north part of Minqiao fault anticline in Jinhu sag in Subei basin, multi-bedding volcanic reservoir in Funing formation of Palaeocene has been found, dominated by fissure/fracture in reservoir pore space. The calculated results show that the fissure/fracture-developed areas occur in the east, middle and west parts of the fault block, with fracture orientations of NWW, EW and SN, which are proved by the oilfield development status. References | Related Articles | Metrics

Calculation of Wellbore Steam Parameters for Extra-and Super-Heavy Oil Wells MA Xin-fang, WANG Wen-xiong, ZHANG Ting, XU Ming-qiang 2007, 28 (1):  75-77.  Abstract ( 84 )   PDF (131KB) ( 403 )   Save By analyzing the related domestic and overseas literatures and based on the theory of vertical multiphase flow and the law of energy conservation, this paper developed a model for calculating the distribution of temperature, pressure and steam quality in wellbore during production of extra-and super-heavy oils by steam injection process. The pressure drops of steam-fluid phases' vertical flow are calculated by this model with classical Orkiszewski method; the calculation of the temperature field is made by assuming one-dimensional steady-state heat conduction from the wellbore center to the cement sheath and two-dimensional unsteady-state heat conduction between the cement sheath and the strata, and the calculation of the steam quality is conducted by considering the change of steam enthalpy. The steam parameters are calculated using the four-rank Runge-Kutta method to make a program. The results given by this model are satisfactory when compared with measured data from the oil fields. References | Related Articles | Metrics

Fractured Low-Permeability Reservoirs: A Model for Single-Well Percolation FENG Jin-de, CHENG Lin-song, LI Chun-lan, GAO Qing-xian 2007, 28 (1):  78-81.  Abstract ( 76 )   PDF (177KB) ( 196 )   Save The anisotropy model with equivalent/continuous medium and the single-well percolation model considering starting pressure gradient in fractured low-permeability reservoirs are developed by means of the parallel-plane and tensor theories. The effects of natural fractures characterization parameters on the reservoir permeability and pressure distribution are studied by these models. The results show that fracture aperture and density have big effects on average reservoir permeability and anisotropy; the pressure distribution and scope are related to the fracture azimuth; the flow interferences exist between the parallel fracture plane direction and the vertical fracture plane direction. The better the fractures development is, the shorter the pressure affect in the vertical direction. Clear understanding of fracture azimuth and the appropriate well patterns and/or well spaces are the key to enhance the conformance or development efficiency of fractured low-permeability reservoirs. References | Related Articles | Metrics

Break Mechanism of Viscoelastic Surfactant Fracturing Fluids ZHAO Bo, HE Cheng-zu 2007, 28 (1):  82-84.  Abstract ( 96 )   PDF (131KB) ( 304 )   Save Fracturing fluid acts as pressure transfer and proppant carrier during the process of fracturing. However, polymer-based fracturing fluid will damage the payzones or even cause production decline of wells due to incomplete degradation of polymer in it. Surfactant molecules are made up of hydrophilic head group and lipophilic tail group, which become micelle by coalescence when dissolved in water. The viscoelastic surfactant fracturing fluid with some salinity is known as clean fracturing fluid for its little damage to fractures and absence of polymer residue. In general, such a fluid doesn't break till mixing with crude oil and gas in reservoirs without adding gel breaker. But this study shows that the viscoelastic fracturing fluid can not break when mixing with natural gas, so gel breaker has to be added for gas well fracturing. A suitable macromolecular gel breaker is presented in this paper. References | Related Articles | Metrics

The Propagation of Pressure Wave from Low Permeability Reservoirs ZHU Sheng-ju 2007, 28 (1):  85-87.  Abstract ( 123 )   PDF (129KB) ( 260 )   Save The propagation of pressure wave of unsteady flow of elastic fluid in low permeability reservoirs is researched using the steady state replacement method. Among the different percolation processes such as planoparallel flow, planoradial flow and spherical centripetal flow, the pressure wave propagating velocity is the fastest under the spherical centripetal flow, and the slowest under the planoparallel flow. And low permeability reservoir is slower than mid-high permeability reservoir in pressure wave propagating velocity. References | Related Articles | Metrics

A Fractal Study on Pore Structure of Sandstone in Extra Low Permeability Reservoirs—An example of Y and Z blocks in Ansai oilfield MA Zhan-qi, REN Xiao-juan, ZHANG Ning-sheng, LI Zhuan-hong 2007, 28 (1):  88-91.  Abstract ( 65 )   PDF (159KB) ( 234 )   Save This study of mercury injection curves from cores of extra low permeability reservoirs in Y and Z blocks in Ansai oilfield shows that the reservoirs are of singular and multiple fractal natures using fractal geometric formula with two parameters. The linear relation assumes between the mean characteristic parameter, sorting coefficient, variation coefficient of pore structure by rectangular method and the fractal dimension by integrated linear regression, indicating that the fractal dimensions can be used to quantitatively describe the heterogeneity of reservoirs. Also, the microscopic analysis of pore structure with different fractal feature comes to the conclusion that the reservoir rocks with similar fractal nature have similar pore type, depositional environment and diagenetic process, and the fractal dimension will increase with pore throat radius (or total number of pore throats) decreasing. Therefore, it is proposed that application of fractal nature to classification of deposition-diagenesis facies is probably a feasible method. References | Related Articles | Metrics

A Prediction of Water Breakthrough Time in Gas Reservoirs with Bottom Water WANG Hui-qiang, LI Xiao-ping, YANG Qi, GONG Wei, ZENG Yu-qiang 2007, 28 (1):  92-93.  Abstract ( 142 )   PDF (83KB) ( 296 )   Save Based on the theory of percolation flow through porous media, a study on prediction of water breakthrough time in bottom-water gas reservoirs is presented. Through mathematical calculations, a formula to determine the time of water breakthrough in bottom-water gas wells is derived. In the formula many factors are taken into account, such as perforating degree, gas-water mobility ratio, Irreducible water saturation, residual gas saturation, etc. Case study indicates that for a gas well with constant production rate, the relationship between the time of water breakthrough and the perforating degree assumes asymmetrical convex curve. References | Related Articles | Metrics

Numerical Simulation of Exploration Methods for Kekeya Condensate Oil-Gas Reservoir MOU Wei-jun, CHE Chao-shan, WANG Xin-yu, DENG Xin-liang, CHEN Shi-bing, CUI Tao-feng, ZONG Wei 2007, 28 (1):  94-96.  Abstract ( 77 )   PDF (161KB) ( 186 )   Save X42-X51 reservoir of Kekeya condensate gas field is a low permeability gas reservoir. For rational exploitation of this reservoir, the exploitation methods such as suitable well pattern and horizontal drilling technology are studied. On the premise of the main structural framework, basic reservoir characteristic and original fluid phase behavior property of X42-X51 condensate gas reservoir, an analogy model for high and low permeability-mixed distribution is developed. Applying numerical simulation technology, the methods for exploitation of the condensate gas reservoir with low permeability are studied. The results show that location of well in high permeability area benefits the production of both high permeability area and low permeability area; horizontal well/drilling is of high productivity and low pressure difference, hence, the recovery of gas or condensate could be enhanced obviously and the development period of such field be effectively reduced. References | Related Articles | Metrics

Application of Isotopic Tracer to Study of Residual Oil Distribution—An example of M pool in Yumen Laojunmiao oilfield ZHANG Hu-jun, LIU Ya-jun, YANG Hui-ping, LI Ke-qing, ZHONG Chong-bi, HOU Zhi-guang, LI Shi-wen, TANG Xi-ming 2007, 28 (1):  97-100.  Abstract ( 86 )   PDF (204KB) ( 324 )   Save Laojunmiao oilfield in Yumen is the oldest field in China developed with modern technologies and by waterflooding process. Since 1967, several methods such as well logging, reservoir engineering, core analysis, numerical simulation and water salinity analysis have been adopted for study the residual oil distribution in reservoirs in different periods or stages of development. However, the studies have shown that each of these methods has both peculiarity and limitation of its own. It is indicated that isotopic tracer injection is more suitable for revealing in-situ oil-water distribution and residual oil status. The principle of this technique includes that two isotopic tracers are injected into injection wells. The peak concentration change and the time-difference of the tracers produced from opposite oil wells will be shown on their curves. Then, the injection-production relations analysis, the reservoir heterogeneous parameters determination and the residual oil saturation evaluation are conducted using the tracer interpretation software in terms of chromatographic fractionation theory and convection-diffusion theory. Such an isotopic tracer technique has been used to Wellgroup-4252 of M pool in Laojunmiao oilfield. It is indicated that it is a simple, visual and effective method for study of the residual oil distribution in this old oilfield by waterflooding process. References | Related Articles | Metrics

3D Seismic Technique and Application for Exploration of Complex Fault Belt YU Gong-ming, ZHANG Yong-hua, LIANG Yun-ji, LI Feng, ZHAO Yu-qing 2007, 28 (1):  101-103.  Abstract ( 79 )   PDF (225KB) ( 225 )   Save In view of the burial characteristics of exploration targets, complex surface and geological conditions in steep slope zone of southern Biyang sag, the problems such as the structural fragment, large fault plane dip angle in the basinal boundary and lateral lithology variation near the fault belt occurred during previous seismic exploration are analyzed, and corresponding methods for them are proposed. In order to solve these problems, the technicians responsible for data acquisition and processing as well as interpretation are cooperated together in line with the guide of geologic model to optimize observation system by computer modeling, select a reasonable shot depth by microlog and refraction data, and bury geophones by drilling hole in piedmont zone. For data processing, the prestack depth migration profile is used to make the imaging of boundary large fault planes distinct and their locations reliable, including that the minor fault points and the interlayer contacts are clear, so that it is convenient for geologists to make a precise interpretation. References | Related Articles | Metrics

Application of Free C and H Isotopes in Normal Alkane to Correlation of Oil Sources in Huanghua Depression LIU Jin-ping, GENG An-song, XIONG Yong-qiang, LI Yong-xin, ZHU Gui-juan, ZHANG Ying-xin, LI Yu-sheng 2007, 28 (1):  104-107.  Abstract ( 106 )   PDF (182KB) ( 273 )   Save The free carbon and hydrogen isotopes in n-alkane from the Paleozoic source rocks in Huanghua depression are determined using techniques of GC-IRMS and GC-TC-IRMS to reveal the isotope compositions in different sedimentary environments. The results indicate that the δ13C and δD from n-alkane of Lower Paleozoic (marine facies) source rocks range from -29‰ to -33‰ and from -110‰ to -140%; while the δ13C and δD from n-alkane of Upper Paleozoic (transitional facies) source rocks range from -27‰ to-29‰ and from -140‰ to-170‰, respectively. From the marine facies to the transitional facies, there obviously exist the trend of rich-δ13C and poor-δD for the n-alkane. These also show that sedimentary environment could be the main factor controlling the isotopic compositions. It is concluded that in complex petroliferous systems, free C and H isotopic compositions and distributions from n-alkane are of significance in oil source correlations, and could be applied to investigation of related kerogens and sedimentary environments. References | Related Articles | Metrics

Features of Proved Petroleum Reserves Report in Terms of the New Classification Standard ZHAO Wen-zhi, BI Hai-bin, LI Jian-zhong, WANG Yong-xiang 2007, 28 (1):  108-111.  Abstract ( 89 )   PDF (127KB) ( 228 )   Save The petroleum reserves researches have been paid much more attention to since promulgation of the new standard for petroleum resources/reserves and implementation of reformed/improved reserves supervision methods. The common desire of domestic reserves supervision circle is how to improve the research level and allow reserves report to hold its important space in scientific report appraisal. First of all, the major problems available in reserves reports are discussed. Then, several points of the report that should be followed in terms of new standard are proposed, including precise terms, normalized style, focusing on oil-gas-water system and effective pay as well as data integrity and study reliability. The authors hope that a brand-new prospect will be created by further efforts of reserves researchers at home. References | Related Articles | Metrics

Re-Under standing of Low-Grade Petroleum Resources in Junggar Basin DONG Guang-hua, QIN Li, LEI Ling, WANG Cong-le, SONG Jun-xin, ZHANG Jun 2007, 28 (1):  112-115.  Abstract ( 113 )   PDF (137KB) ( 222 )   Save The systematic investigation of the relevant literature on low-grade reserves at home and abroad is made, and the definition and classification of the "low-grade" reserves in Junggar basin are conducted accordingly. Study shows that the low-grade reserves play a significant role in petroleum exploration and development in China. In terms of this definition, it is estimated that the low-grade reserves in Xinjiang Oilfield Company account for 66.99% of the total proven reserves by the end of 2005, of which the produced "high-grade" thin oil reserves that turned into the low-grade reserves due to water cut increase or production rate decline account for 8.8%. Such highgrade reserves are mainly distributed in Triassic and Permian systems of Karamay, Luliang, Cainan and Hongshanzui oilfields. In addition, the major areas for further searching for the "high-grade" reserves could locate the hinterland and southern margin of Junggar basin. References | Related Articles | Metrics

Genesis of High-Wax Oil in Nanyang Sag LI Shui-fu, ZHANG Dong-mei 2007, 28 (1):  116-118.  Abstract ( 122 )   PDF (244KB) ( 232 )   Save The oil that wax content is over 8% is called high-wax oil. Traditionally, it is considered that wax is normal alkane with high molecular weight, and it is originated from higher plant. Recent-year studies demonstrate that wax consists of not only high-molecularweight normal alkane, but also isoalkane, naphthene and olefin; and the origin of wax is not only from high plant, but also lower hydrobiont and lacustrine algae which are as important contributors to the wax. The wax content of crude oil in Nanyang sag ranges from 40% to 60%, and the type of organic matter is dominated by Type IIB~III. It is suggested that the high-wax oil is mainly originated from terrestrial higher plant, while lower hydrobiont is accidental. References | Related Articles | Metrics

Geological Era Adscription and Petroliferous Formation Classification of Shinan-31 Wellblock in Junggar Basin TANG Yong, ZHOU Wen-quan, ZHAO Ke-bin, XU Chang-sheng, WANG Lin, WU Bao-cheng, HAN Yong-qiang 2007, 28 (1):  119-121.  Abstract ( 110 )   PDF (161KB) ( 208 )   Save In view of disputable adscription of geological era and petroliferous formation classification of Shinan-31 Wellblock in Junggar basin, the systematic analyses of existing data from paleontology, core sample and geophysical prospecting are conducted. The geologic era of the petroliferous strata is dated as Qingshuihe stage of Early Cretaceous, which is higher than the basal conglomerate of Cretaceous in horizon, through the correlation of sand layers and the identification and tracing of the seismic sequence boundary by means of sequence stratigraphy and sedimentary system theory. The reservoir type of Shinan-31 Wellblock belongs to the lithologic reservoir with upward pinchout sands. References | Related Articles | Metrics

AVO Abnormal Responses from Gas Pools with High-Low Effectiveness LIU Ya-ming, XUE Liang-qing, PAN Ren-fang 2007, 28 (1):  122-124.  Abstract ( 86 )   PDF (126KB) ( 257 )   Save On the basis of petrophysical experiment of natural gas reservoir, the intrinsic relations between reservoir physical property, lithology, gas-bearing nature and AVO abnormal responses from gas reservoirs are summarized, including analysis of the responses sensitivity to the gas reservoirs. For gas reservoirs with high-low effectiveness, the variable porosity and variable gas saturation are simulated by AVO technique, coming to the conclusion that the AVO abnormal responses from gas reservoir with good gas-bearing property belong to Class-III, while those from one with poor gas-bearing property belong to Class-I and Class-II. Therefore, this AVO abnormal response could be used to improve the accuracy of parameters for interpretation and precision of fluid property recognition as references of regional prospecting evaluation. References | Related Articles | Metrics

Improvement of the Critical Production Rate Formula for Bottom-Water Reservoir with Partition Board Proposed by Dr. LI Chuan-liang HE Wei, HUANG Quan-hua, REN Peng, ZHEN Guo-shu 2007, 28 (1):  125-126.  Abstract ( 78 )   PDF (85KB) ( 238 )   Save In 1993, a formula for critical production rate of oil well in bottom water reservoir with partition board was proposed by Dr. Li Chuan-liang, but this formula did not contain any parameter of well penetration, i.e. did not take the perforated thickness into account. it is hard to just perforate the partition board of well in fact, so a modification for it should be made on Li's formula by adding a critical production rate contributed from the bottom of performed interval to the partition board. Case study indicates that the improved formula is more suitable for the real reservoirs than before. References | Related Articles | Metrics