Table of Content

01 August 2006, Volume 27 Issue 4 Previous Issue    Next Issue

For Selected:

Download Citations EndNote Reference Manager ProCite BibTeX RefWorks

Toggle Thumbnails

The Structural Belt Compartment of Carboniferous Basement and Petroleum Distribution in Junggar Basin LIN Zu-bin, WU Xing-hua, WANG Yan, SHI Xin-qin 2006, 27 (4):  389-393.  Abstract ( 95 )   PDF (646KB) ( 212 )   Save The II-Class structural units of Carboniferous basement are regionally classified into such framework as one terrace, two uplifts and three depressions, based on data from surface gravity and geomagnetic survey. Between the depression and the uplift is linked by faulted terrace and fracture belt. 275 prospecting wells were drilled here, and 10 medium-sized complete oil-gas fields have been found by 31 wells of them, all of which are concentrated in traps of successive depression-side uplifts (Kz, Mz) on the fault terrace and fracture belt; in traps of non-successive depression-side uplifts (C, P), only 21 oil/gas-yielding isolated points or wells have been discovered, with 160 water wells due to lack of oil-feeding channels linked with hydrocarbon-generating source rocks; 47 dry wells that are drilled in shale between two distributary channels adjacent to the lobate delta and in tuff around the buried hill. It is suggested that 25 locations of 9 IIIClass anticline structural belts are favorable for finding out proved or controlled reserves. References | Related Articles | Metrics

Petroleum Exploration of Distributary Channel in Ramp Region of Continental Fault Basin LIU Chuan-hu 2006, 27 (4):  394-397.  Abstract ( 94 )   PDF (352KB) ( 184 )   Save Multi-stage distributary channels are generally developed in ramp region in continental fault basin and annularly distributed around hydrocarbon-generating basins, with good reservoir quality and source-reservoir-caprock assemblage conditions. If faults occur on updip distributary channels, their hydrocarbon-accumulating conditions will be more favorable. But it is absolutely difficult to study such distributary channel reservoirs, because they are characterized by multiple types, widespread distribution, highly hidden nature, multiple combinations between fault and channel and peculiar hydrocarbon-accumulating feature. Hence, the prerequisite for high efficiency prospecting of the distributary channel reservoirs will focus on precise determination of the distribution of channels, study one by one of the controlling factors of hydrocarbon accumulation and analysis layer by layer of the reservoir distribution. In view of analysis of sedimentary system, this paper elaborates the reservoir characteristic, the mechanism and regularity of hydrocarbon accumulation in distributary channels. The methods for such reservoir description would be as a guide for research of other similar types of reservoirs in different areas. References | Related Articles | Metrics

Petroleum Geology and Exploration Prospect of Mesozoic and Cenozoic in Taixinan Basin, Northern South China Sea HE Jia-xiong, XIA Bin, CHEN Gong-yang, SUN Dong-shan 2006, 27 (4):  398-402.  Abstract ( 128 )   PDF (331KB) ( 442 )   Save Taixinan basin, one of Mesozoic and Cenozoic petroliferous basins, is located in marginal basins of eastern continental shelf in northern South China Sea, adjacent to Pearl River Mouth basin. It is of good petroleum potential and exploration prospect for its vantage point with rich natural gas resources. This basin consists of such three structural units as north sag, south sag and central uplift zone. Because of less effort for its exploration and research, the petroliferous structures of CFC, CFS and CGF focusing in central uplift zone have been found so far, which belong to Oligocene sandstone reservoir and Cretaceous fractured reservoir. Because the central uplift zone is regionally situated in favorable petroleum migration area in center of the basin, with good petroleum accumulation conditions, the commercial oil and gas found so far are centralized within this zone. Therefore, the central uplift zone should be the best petroliferous abundance zone and prospective region. To take more efforts for exploration, make a thorough research of this zone and make in-depth studies of its hydrocarbon-enriched rule would be the key for quick breakthrough of Taixinan basin. References | Related Articles | Metrics

The Origin of Domal Seismic Reflection Anomaly Bodies of Upper Ordovician in Northwestern Tazhong Area XU Guo-qiang, LU Hui-li, WU Heng-zhi, LI Guo-rong, LIU Shu-gen, YAN Xiang-bin, WU Wei-hang 2006, 27 (4):  403-406.  Abstract ( 82 )   PDF (540KB) ( 178 )   Save The Lianglitage formation of Upper Ordovician is rich in reef, which led the domal seismic anomaly bodies in Tazhong area of Tarim basin to be interpreted as reef in recent years. According to the integrated study of seismic and geological analysis, it is indicated that the reef or multiple circled complex reef-banks can not be recognized directly in conventional seismic profiles because the thickness of the reef is less than one eighth of wavelength, the width of it is less than one radius of Fresnel zone. Reefs or complex reef-banks are always invisible and intermixed in the strong reflection (T74), the top boundary of successive carbonate overlain by interbedded limestone and mud or/and the under 1~2 feeble and discontinuous reflections. Those domal seismic anomaly bodies overlying the strong reflection of T74, with inner bedding configuration composed of mid-strong reflections, reflect the interbedded configuration of limestone or argillaceous limestone with mudstone, which are the products of sedimentary environment with low-and high-energy transition zones, and the low probability of reef-bank deposits within them. The accurate interpretation shows that such domal bodies are the seismic reflections of nonreef-bank deposits of low angle thrust faults, slope slump accumulative zones and turbidite fans. References | Related Articles | Metrics

Study Methods for Reservoirs with Low Amplitude Structure WANG Yan-zhang, LIN Cheng-yan, WEN Chang-yun, LI Bo-xi, ZHU Yong-feng 2006, 27 (4):  407-409.  Abstract ( 86 )   PDF (365KB) ( 238 )   Save With further exploration and development of oil fields, the reservoirs with low amplitude structure are paid more attention to. Two origins and multi-identifications for such reservoirs are discussed and presented, integrated with studied area conditions. The identification methods include the coherent data volume processing technique with predominant frequency band to distinguish from small faults, the plane slice technique, auto-tracing technique, the spilling point restriction technique, the variable velocity mapping technique and the flow chart for studying the low amplitude structures. Application of these techniques to Neogene reservoir in Gaoliu structural zone of Nanpu sag, Ten low amplitude structures have been found, three of which been drilled, obtaining commercial oil flows. Also, two low-amplitude-structure reservoirs at C5 unit (Es2) in Chunhua field of Dongying sag have been found, and five wells been drilled with good responses. References | Related Articles | Metrics

The Geochemical Characteristics of Crude Oil and the Correlation of Oil Sources in Yingjisu Sag in Tarim Basin YANG Yong-cai, CHANG Xiang-chun, ZHANG Zhi-huan 2006, 27 (4):  410-413.  Abstract ( 77 )   PDF (252KB) ( 195 )   Save The geochemical characteristics of crude oil and source rocks in Yinjisu sag are summarized. The genetic types of crude oil are classified, and the correlations between oil-oil and oil-source are conducted by applying light hydrocarbons, biomarkers, and carbon isotopes. The study shows that palaeosalinity of Jurassic carbonaceous mudstone and coal deposit of Jurassic in Huayingcan-1 Well are low in both palaeo-salinity and maturity, not reaching the mature threshold. Crude oil of Jurassic in Yingnan-2 Well is in stage of low maturity, mainly coming from low-salinity and oxidizing Mesozoic humic source rocks, with property of mixed sources. And oil of Jurassic in Longkou-1 Well is originated from hypersaline and anoxic reducing Cambrian-Lower Ordovician sapropelic source rocks. Oils of Jurassic in Huayingcan-1 Well, Cambrian in Tadong-2 Well and Jurassic in Longkou-1 Well are the same source in stage of thermal maturity. References | Related Articles | Metrics

Organic Geochemical Characteristics of High Wax Oils in Nanyang Sag LI Shui-fu, HE Sheng, ZHANG Dong-mei 2006, 27 (4):  414-418.  Abstract ( 82 )   PDF (342KB) ( 408 )   Save The crude oil from Nanyang sag is characterized by low density, low viscosity, low sulfur content and high freezing point, being normal crude oil with high-to abnormal high-wax content, high saturated hydrocarbon content, saturated/aromatic hydrocarbon ratio of more than 3.0, V-shape distribution of C27—C29 regular steranes with high isomerization of C29 sterane and the S/R+S ration of 0.3~0.6. The terpane is dominated by penta-triterpanes and long-chain tricycloterpanes; the non-hopane series (especially gammacerane) are quite abundant. The gammacerane index of individual sample is up to 1.3, indicating a high-salinity and strong-reduced environment. The aromatic components are dominated by phenanthrene and then the naphthalene series. The tri-aromatic steroids content of crude oil is relatively low in Zhangdian area and shows a wide range. References | Related Articles | Metrics

Controlling Factors of Pore Development of Permian He-8 Section Reservoir in Suligemiao Gas Field YANG Wen-xiu, ZHANG Liu-ping, CHEN Meng-jin 2006, 27 (4):  419-421.  Abstract ( 86 )   PDF (288KB) ( 174 )   Save The major reservoir of Permian He-8 section in Suligemiao gas field is a deposit with medium sands, coarse sands and fine conglomerate. The complicated course of Diagenesis results in the complexity of pore development in the reservoir. This paper presents the analysis of major controlling factors of the pore development by means of multiple stepwise regression analysis in order to guide the further exploration. The result shows that the porosity of sandstone reservoir in the studied area is mainly controlled by both sedimentation and diagenesis. This method and conclusion could not only be as a guide for further exploring the favorable reservoir, but also offer positive basis for reference for similar study of other areas. References | Related Articles | Metrics

A Study on Variation Function of Channel Mouth Bar—An example of a gas filed in Indonesia YANG Yong, WU Lei, GUO Kai, LIU He-nian 2006, 27 (4):  422-424.  Abstract ( 91 )   PDF (216KB) ( 228 )   Save Based on the analysis of the heterogeneity of channel mouth bar reservoir, the horizontal variation function is given and matched by using the porosity data from the multi-directional horizontal wells. Combined with the variation function of vertical wells, it is considered that the statistic distribution of the delta front mouth bar reservoir parameter in horizontal direction is similar to that of reservoir parameters in vertical direction, and the variation functions are dominated by spherical model. The vertical range of vertical wells averages about 1.2 m, which represents the vertical thickness of single mouth bar; the plane long-axis range of horizontal wells ranges from 24 m to 36 m and the short-axis range of them ranges from 8 m to 16 m, which represent the length and width of single mouth bar, respectively. The ratio between the long-axis range and short-axis range is about 2:1～3:1; the ratio between the plane long-axis range and vertical range is about 20:1～30:1, and the ratio between the short-axis range and vertical range is about 6:1～13:1. References | Related Articles | Metrics

The Pre-Conditional Conjugate Gradient Algorithm for Inversion of Seismic Acoustic Impedance HUANG Wen-song, NIAN Jing-bo, LIU Xi-wu 2006, 27 (4):  425-428.  Abstract ( 93 )   PDF (294KB) ( 264 )   Save Seismic acoustic impedance linear inversion algorithm is studied. Based on Cauchy criteria, the regularized sparse inversion can be made by using pre-conditional conjugate gradient algorithm (PCGA) in simultaneously iterative inversion of reflection factor and wavelet. For solving the inversion problem by PCGA, it is better to solve the original linear system rather than the normalized system for the good matrix condition number. The initial wavelet estimation and acoustic impedance interpretation methods are presented. The real data verification shows that the wavelet, reflection factor and acoustic impedance given by PCGA are more accurate, quicker convergent and value stable than the existing direct sparse inversion method. References | Related Articles | Metrics

Gas-Bear ing Formation Identification in High Evolution Area Using Reservoir Bitumen Characteristic HU Shou-zhi, FU Xiao-wen, WANG Ting-dong 2006, 27 (4):  429-431.  Abstract ( 84 )   PDF (169KB) ( 179 )   Save The fingerprint characteristics on mass-chromatograph chart of saturated hydrocarbon extracted from reservoir bitumen is widely used to identify reservoir fluid types, with the development of technology and method of petroleum geochemistry. However, the reservoir fluid type in high-evolution area can't be exactly identified with this method. Based on analysis of the reservoir feature in high-evolution area, a new reservoir bitumen classification is suggested. In view of the soluble ability in the organic solvent, the reservoir bitumen in high-evolution area can be divided into two types of soluble reservoir bitumen, one is in free state and the other in included state. The identification of these two soluble reservoir bitumen is integrated with the available geochemistry methods for recognizing oil, gas and water zones/layers, hence proper identification of gas-bearing formation and non-gas-bearing formation in the high-evolution area is exactly made, providing sound scientific basis for development scheme preparation and prospect evaluation of natural gas exploration. References | Related Articles | Metrics

A Study on Origin of Highly Evolutionary Natural Gas in Mahai Gas Field, Qaidam Basin HU Xiong, LI Yan-jun, FU Xiao-wen, WANG Qiang, LIANG Yan 2006, 27 (4):  432-434.  Abstract ( 95 )   PDF (245KB) ( 197 )   Save The feature of natural gas in Mahai gas field that was less studied before is integrated with fluid inclusion test results, the burial history and thermal evolution history of source rocks as well as structural development history in this paper. It is indicated that two stages of oil-gas fillings are found in Mahai structure. Oil at the first stage ended in dispersal for poor preservation; at the second stage Mahai structure only captured the highly evolutionary gas from Yibei sag. Gas from Mahai gas field and Nanbaxian field belongs to the same genetic type, but the latter is high-and over-mature coal-formed gas related with Lower Jurassic source rocks in Yibei sag. References | Related Articles | Metrics

Mechanisms of Petroleum Accumulation of Structural Reservoir in No.5 Unit of Lenghu Area in Qaidam Basin SUN De-qiang, LIU Hai-tao, YU Hui-long, LIU Jin-cheng, ZHANG Tao 2006, 27 (4):  435-439.  Abstract ( 89 )   PDF (380KB) ( 206 )   Save No.5 unit of Lenghu area is one of important targets for exploration of Lenghu structural zone in northern margin of Qaidam basin, where the huge source rocks of Jurassic was found by Well Lenke-1, thus demonstrating its abundant source potentials in this area. This paper presents the typical mode of hydrocarbon accumulation of structural reservoirs in Lenghu-5 structural zone, showing that there exist two stages of hydrocarbon accumulation, accordingly forming two sets and types of reservoirs. One is deep and the other is shallow. The original deep one (J-E) was formed during E3-N1, and the secondary shallow one (N) formed after end of N2. The shallow one is lower than the deep one in hydrocarbon maturity; the former is characterized by early charging and late forming, and the latter is by early forming and long-term charging. References | Related Articles | Metrics

Estimation of Erosion Thickness of Jurassic in Bohu Depression, Yanqi Basin ZHANG Hui, DUAN Xin-jian, HANYu-ji, ZHANG Hai-jiao, LIN Shui-qing 2006, 27 (4):  440-442.  Abstract ( 83 )   PDF (309KB) ( 179 )   Save The estimation of erosion thickness is a foundation for studying palaeostructural characteristic, modeling source rock thermal evolution history and analyzing palaeo-fluid potential. Based on the geologic feature and available data of Yanqi basin, 27 exploratory wells are chosen in Bohu depression, for which strata erosion thickness of well is estimated by using mud interval transit time method, and then taking these data as the constraining points, 10 seismic profiles are selected, finally, the whole erosion thickness of Jurassic in Bohu depression is estimated by using seismic profile tracing technique. The result shows that vertically, each formation of Jurassic undergoes erosions to a certain extent, the most eroded series is Upper Jurassic, the second is Toutunhe formation and Xishanyao formation of Middle Jurassic, Sangonghe formation and Badaowan formation of Lower Jurassic are well preserved relatively. Laterally, the different areas in Bohu depression are dissimilarly eroded, the most eroded area is Zhongmachang low swell, the second is the area nearby Yannan fault in the northern Bohu depression, while Sishilicheng sub-sag, Qilipu sub-sag in the north sag and Baotouhu sub-sag in the south sag are eroded slightly. References | Related Articles | Metrics

The Rolling Exploration and Development of Flood Plain Reservoir in Northwestern Margin of Junggar Basin QU Juan, ZHANG Wen-sheng, Geng Mei 2006, 27 (4):  443-445.  Abstract ( 87 )   PDF (189KB) ( 210 )   Save The data from reservoir of Lower Karamay formation of District 4-(2) in northwestern margin of Junggar basin are applied to elaborate the lithology, the depositional structure and the type of sedimentary facies. The flood plain-like alluvial fan, a type of alluvial fan different from other districts in Karamay oilfield, is then discovered. This alluvial fan is characterized by thin, narrow and straight sand bodies as well as developed gully microfacies (hydrocarbon-bearing facies). Also, this paper presents the measures and suggestions for effective exploration and development of such oil-gas fields. References | Related Articles | Metrics

Hydrocarbon Detection in Hongtai-Gedatai Area, Taibei Sag LI Zai-guang, LIU Jun-tian, YANG Zhan-long, LI Lin, JI Wei-hua, WANG Zhong-jie 2006, 27 (4):  446-448.  Abstract ( 78 )   PDF (155KB) ( 180 )   Save Hydrocarbon detection can be made in two steps: recognizing the seismic information of hydrocarbon and tracing for its distribution horizontally and vertically. The effective method is to extract seismic dynamic parameters of hydrocarbon reservoir in small time window based on the seismic and geological analysis of drilled hydrocarbon-bearing stratum, and then to determine its distribution horizontally and vertically by combination of seismic multi-attribute with the known calibration of gas layers. This method is applied to the gas layers of Ht8, Ht6, Ht203 and Ge8 Wells that found in recent years in Hongtai-Gedatai area, Taibei sag of Tuha basin, which is of a significance for guiding prospecting in this area in next stage. Well Ht13, Ge11 and Ge13 wells newly drilled in advantaged gas detection area have obtained commercial oil-gas flow rather than Ht12, Ht205 and Ge14 wells outside the advantaged area, which support the reliability of this method. References | Related Articles | Metrics

The Effect of CO2 Injection Process on Production Response of Fang-48 Reservoir in Daqing Oilfield ZHAO Ming-guo, LIU Chong-jiang 2006, 27 (4):  449-451.  Abstract ( 79 )   PDF (126KB) ( 251 )   Save Fang-48 fault block in Daqing oilfield is a super low permeability oil reservoir. The physical modeling studies are conducted by processes of water flooding, CO2 flooding, CO2 stimulation, CO2-water alternate flooding, water-CO2 alternate flooding. The experimental results indicate that the water breakthrough is early, water cut rises rapidly and water injectivity is low. Among the processes of CO2 flooding, CO2 stimulation followed by CO2 drive allows the highest cumulative oil recovery factor, in turn declining for water-CO2 alternate flooding, CO2 drive, CO2-water alternate flooding, CO2 stimulation. In view of the cumulative gas-oil ratio, it is the highest for CO2 stimulation, in turn declining for CO2 drive, water-CO2 alternate flooding, CO2-water alternate flooding, CO2 stimulation followed by CO2 drive. In light of the CO2 injectivity, it is the highest for CO2 drive, in turn declining for water-CO2 alternate flooding, CO2-water alternate flooding. Considering the production response and the CO2 injectivity, the development scheme of Fang-48 fault block should be firstly the CO2 stimulation followed by CO2 drive, secondly by water-CO2 alternate flooding. References | Related Articles | Metrics

An Analysis of Effect of Microorganism on Hydrocarbon Seepage YI Xiang-yi, LU Yuan, WANG Hui 2006, 27 (4):  452-455.  Abstract ( 78 )   PDF (393KB) ( 206 )   Save Microbial enhanced oil recovery (MEOR) is a new technique combining with biology and oilfield development technology, by which EOR of low permeability reservoirs could increase through improving the in-layer and interlayer contradictions. MEOR, as one of important stimulation measures at late stage of oilfield development, is characterized by low cost, simple operation and according with the demand of environment protection, etc. The effects of MEOR include as follows: being favorable to oil-gas percolation, changing wettability of rocks, improving hydrocarbon migration, reducing surface tension of emulsified oil, decreasing crude viscosity and improving sweep efficiency, etc. Meanwhile, its negative influences under the reservoir conditions should be recognized such as influence of microorganism on reservoir permeability, influence of the products of microorganism on formation plug, influence of iron sulfides precipitation and biochemical affection of microorganism. References | Related Articles | Metrics

The Influences of Irreducible Water and Depletion Rate on Critical Flow Saturation of Gas Condensate SUN Feng-jing, GUO Ping, DU Jian-fen, JIANG Tong-wen, WANG Xiao-qiang, LIAO Fa-ming 2006, 27 (4):  456-458.  Abstract ( 75 )   PDF (141KB) ( 190 )   Save In recent years, the massive researches about critical flow saturation of gas condensate have been made at home and abroad. However, the results from different methods and tools showed big differences and even opposite ones among them. The self-developed ultrasonic wave test system is used to make five tests on gas condensate critical flow saturation in this paper, including two groups of contrast experiments considering the irreducible water influence and a group of contrast experiment considering depletion rate influence. The experimental results show that the gas condensate critical flow saturation is generally low, approximately about 10%, and the saturation at high depletion rate is lower than that at low depletion rate, which indicates that the high depletion rate is advantageous to flow of in-situ gas condensate; the existence of irreducible water can reduce the gas condensate critical flow saturation. References | Related Articles | Metrics

A Study on Numerical Simulation of Steam Stimulation for Super Heavy Oil Reservoir MA Xin-fang, WANG Zhuo-fei, XU Ming-qiang, ZHANG Shuai-qian, HE Jun, WEI Xin-chun 2006, 27 (4):  459-462.  Abstract ( 95 )   PDF (254KB) ( 191 )   Save Steam stimulation is a kind of economic and effective process for improving production of heavy oil. In District 9-(7) in Karamay oilfield, the viscosity of gas-free crude ranges from 2 400 mPa·s to 961 000 mPa·s at 50℃, averaging 452 029 mPa·s, belonging to super heavy oil. Based on these characteristics, the numerical simulation technique is applied to study of the main parameters given by steam stimulation process, including optimized calculation of the parameters such as steam injection intensity, steam injection velocity, cyclic steam injection volume, steam injection pressure, shut-in time and steam quality, as well as recommended the optimized program. The steam stimulation responses from the steam huff and puff wells are forecasted, obtaining the cycle production rates in different cycles. The results can be as a guide for super heavy oil production in District 9-(7) by steam stimulation process. References | Related Articles | Metrics

Some Considerafions about Soak Time by Steam Stimulation Process ZENG Yu-qiang, LIU Shu-zhi, SUN Ai-yin, LI Hong-chang, ZHANG Jin-liang 2006, 27 (4):  463-465.  Abstract ( 154 )   PDF (181KB) ( 219 )   Save Shut-in for soaking is an indispensable process during steam stimulation. For a long period of time, the determination of soak time relies on field experiences without a theoretic basis. In addition, the effect of soak time on heated radius is not well understood. This paper presents the calculation formula for determination of reasonable soak time and heated radius at end of soaking by analysis of changes of oil layer and steam energy during soaking period, based on basic theories of reservoir engineering and heat transfer. This new consideration is of positive theoretical meaning to re-understand the steam-soak process. References | Related Articles | Metrics

A Theoretical Approach to the Relationship between Cumulative Water-Injected Rate and Water Cut in Water flood Oilfield ZHANG Ji-feng, TIAN Xiao-dong, GUO Wei-qi, WANG Tian-zhi 2006, 27 (4):  466-467.  Abstract ( 111 )   PDF (115KB) ( 219 )   Save The cumulative water-injected rate is one of important indices for evaluating the water injection status and effect of a waterflood oil field. The mathematic expressions between cumulative water-injected rate and water cut are deduced and discussed based on the definition of cumulative water-injected rate and water drive characteristic curves, including the expressions for B-type, C-type and D-type curves, taking C-type curve as an example. The theoretical expressions could be as a guide for response evaluation, stimulation and modification of a waterflood oilfield. References | Related Articles | Metrics

A Study on Feasibility of Polymer Flood in LD10-1 Oil Field WANG Hong-shen, SHI Yong, ZHOU Ya-li, MOU Song-ru 2006, 27 (4):  468-470.  Abstract ( 76 )   PDF (151KB) ( 208 )   Save There are some prominent problems nowadays that water cut rises quickly and the recovery percent is low for some fields put into production in Bohai offshore oilfield. And because of the limit of the platform life span, an offshore oilfield will be developed for only twenty years. So it is a difficult technology problem to be solved that how to produce more oil as quickly as possible during the platform life span. Through analyzing the geology and reservoir quality of LD10-1 oilfield, the reasonable geologic model and reservoir numerical model are developed, based on which the optimized design study of polymer flood project has been carried out, and finally the recommended projects are given in this paper. The study indicates that it is feasible to early inject polymer at LD10-1 oilfield, but it has some difficulties that both the polymer injection rate and the slug quality concentration cannot be very high. References | Related Articles | Metrics

A Study on Pressure Sensitivity of Fractured Low-Permeability Reservoirs HAO Ming-qiang, YANG Zheng-ming, LIU Xue-wei, LIU Xian-gui 2006, 27 (4):  471-473.  Abstract ( 78 )   PDF (167KB) ( 212 )   Save A pressure-sensitive effect affects unfavorably the production performance of fractured low-permeability reservoirs with horizontal fractures. With continuing an oilfield development, its formation pressure tends to decline along with the horizontal fractures being closed, the permeability drawdown and the productivity being damaged. Based on the core lab data, this paper presents the affected trend of varied pressure on core permeability, the differences of pressure-sensitive features between low-permeability sand cores with/ without horizontal fractures, and develops a model for steady-state productivity prediction considering the pressure-sensitive effect. Furthermore, the influences of pressure sensitivity on permeability, pressure distribution and productivity of such reservoirs are discussed with calculated example. These results have important instructional significance to highly efficient exploitation of fractured low permeability reservoirs with horizontal fractures. References | Related Articles | Metrics

A Study on Shear Resistance Characteristic of Hydrophobically Associated Water-Soluble Polymer CHEN Ding-zhao, CAO Bao-ge, DAI Qian 2006, 27 (4):  474-477.  Abstract ( 81 )   PDF (179KB) ( 227 )   Save The characteristics of shear recovery and resistance of hydrophobically associated polymer (AP4) in lab fresh water and simulated reservoir brine are tested. The experimental results show that AP4 in both conditions has good behaviors for shear thinning and shear resistance compared with partially hydrolyzed polyacrylamide (HPAM), more indicating that the hydrophobical association effects greatly on shear resistance behavior, and this polymer for oil-gas recovery can be allowed to implementation and application of it for oilgas recovery. References | Related Articles | Metrics

Application of Zero Mean-Based Curve Reconstruction to Seismic Inversion LUO Quan-sheng, ZHAO Ming, ZHANG Xiao-ju, GAO Xian-jin, SHAO Jian-ping 2006, 27 (4):  478-480.  Abstract ( 62 )   PDF (424KB) ( 174 )   Save It is difficult to predict reservoir with wave impedance inversion in areas where the sonic seismogram has no distinct differences between reservoir layers and non-reservoir layers. Curve reconstruction is used in the areas and obvious effects could be obtained. Since the traditional curve reconstruction method changes the original time-depth chart, horizons after inversion have fairly big errors with the original seismic horizons. To reconstruct type curves with a special approach, which makes the mean values of the type curves equal zero, can not only reveal the lithological changes of the targets, but also remain the actual geologic features represented by the original curves. Hence problems occurred in curve reconstruction can be well solved and the reliability of constrained log inversion be improved. The application of this technique in Putaogou region shows that the areal changes of four sand layers of Qiketai formation can be properly predicted in accordance with the geologic understandings. References | Related Articles | Metrics

A New Method for Processing of Modified Isochronal Well Test Data in Low Permeability Gas Reservoir ZHANG Zong-lin, ZHANG Zhen-wen, HU Jian-guo 2006, 27 (4):  481-483.  Abstract ( 85 )   PDF (277KB) ( 204 )   Save Modified isochronal well test plays an important role in productivity evaluation of gas field. For low permeability gas reservoir, it is difficult to keep the bottom hole flowing pressure stable in the stage of continuing flowing of gas well. At the same time, it is also difficult for coefficient B of turbulent flow equation with different time to maintain constant, hence the application of modified isochronal well test is confined. In this paper, the new method for processing of modified isochronal well test data for low permeability gas field was established. By application and case comparison, the results show that this method is more accurate and reliable than existing conventional approaches. References | Related Articles | Metrics

Application of TOPSIS Method to Optimization of Oil-Gas Field Development Scheme ZHAO Ming-chen, CHEN Yue-ming, YUAN Shi-bao 2006, 27 (4):  484-486.  Abstract ( 73 )   PDF (109KB) ( 244 )   Save In light of the applied defects of subjective and objective weight assignment methods of the appraisal approaches for oil-gas field development, the TOPSIS method to comprehensively evaluate the development scheme of oil-gas field is presented. On the basis of the theory and practice of oil-gas field development, a mathematical model by combing with the dynamic indices and the economic indices is developed, by which the comprehensive optimization of oil-gas field development scheme can be made. Taking nine development schemes of a gas field as examples, the ordering results of each development scheme are obtained and compared with those from fuzzy decision and principal element analysis. And then the systematic clustering method is used to verify the conclusions drawn from these three methods. It is indicated that the TOPSIS method has an advantage over the others in optimization of development schemes. References | Related Articles | Metrics

On Evaluation Methods for Producer Stimulation Benefit HUANG Sheng-bo, ZHANG Zhong-hua 2006, 27 (4):  487-489.  Abstract ( 81 )   PDF (107KB) ( 276 )   Save Stimulation requirement and stimulation output occupy some ratio of the total investment and total output. The better stimulation effect and/or benefit should be combined with oilfield development practice, by which the improved cost variation and related economic limit are studied and prepared in order to establish a set of complete and scientific stimulation technologies and economic evaluation methods. This paper presents two models: one is a marginally economic model for stimulation and the other is a structural optimization model for stimulation. They will be used for evaluation of economic feasibility and benefit maximization of the stimulations by means of these advanced economic analysis methods. References | Related Articles | Metrics

The Power Spectral Entropy Identification Method for Water Flooded Zone WANG Ren-yi, WANG Qian, JIANG Bing, FAN Shang-wu 2006, 27 (4):  490-492.  Abstract ( 85 )   PDF (129KB) ( 144 )   Save The information of petroliferous reservoir is hided in the level of differential waveform complexity between the resistivity and porosity log curves of reservoirs. The density of power spectral entropy, on the whole, is an exponential decline curve with frequency augmentation without reference to water flooded extent. Along with water flooded extent reducing gradually, the declining rate of power spectral is reducing and some frequency components are absorbed, the whole of which energy gradually falls. The curve changes gradually from slick to dentate form, and the power spectral entropy increases gradually. The signal power spectral entropy depends on the level of signal complexity and is independent of signal absolute value. It is indicated that the low resistivity oil layer and the high resistivity swept layer and water layer can be much better identified by the identification method of swept layer based on the power spectral entropy characteristic of log signal than by the conventional well log explanation theory. References | Related Articles | Metrics

Re-Discussion of Relationship between Petroleum and Sand-Type Uranium Deposit ZHANG Jing-lian, WEI Ping-sheng, ZHANG Hu-quan, CHEN Qi-lin 2006, 27 (4):  493-497.  Abstract ( 128 )   PDF (163KB) ( 259 )   Save The relationship between petroleum and sand-type uranium deposit is increasingly concerned. There exists paragenetic relationship between uranium ores and petroleum trace elements (Re, Ni and V, etc.), which indicates that they might be all originated from deep sources. The tracing and dating by Pb, Sr, Nd isotopes in crude and bitumen also prove the nature of deep sources. The deposition and formation of sand-ype uranium ores are related with reduction of hydrocarbon, especially with methane and hydrogen. Based on these deep source features and origin relationship between crude oil and uranium, the general criterion for finding out large oil and gas fields is presented, that is, as long as a sand-type uranium deposit is found with low-velocity and highly-conductive zones in the mid-crust, the target of large oil and gas fields could be delineated. References | Related Articles | Metrics

Theoretical Analysis of Dipping Water-Oil Contacts LI Chuan-liang 2006, 27 (4):  498-499.  Abstract ( 189 )   PDF (75KB) ( 196 )   Save Based on the theory of flow in porous media, the analysis shows that the current flow of underground water cannot become the real cause of water-oil contact (WOC) dipping in most cases. According to the theory of petrophysics, the reasons of dipping of WOC could be related to the difference of petrophysical properties resulted from ancient flow direction, and the difference results in the different capillary pressure curves of rocks. Finally, these differences cause the dipping of WOC upward along the ancient flow direction. References | Related Articles | Metrics

Modification of Calculation Formula for Gas Reservoir Volume Factor XIE Long, GUO Xu-qiang, CHEN Guang-jin, MA Qing-lan 2006, 27 (4):  500-502.  Abstract ( 158 )   PDF (105KB) ( 242 )   Save The calculation formula for gas reservoir volume factor in petroleum engineering is introduced. The shortage of calculation formula is analyzed. A modified method is proposed for the calculation formula for gas reservoir. The deviation factor is calculated by PR EOS and Gopal (1977) methods widely used in the petroleum engineering. The gas reservoir volume factor calculation is performed for ten gas reservoir fluids with methane content ranging from 50.56 to 97.75 percent and compared with experimental data. The relative errors average 1.325% and 3.173%, respectively, with the modified calculation formula, compared with the average relative errors of 1.867% and 3.701% with available calculation formula. The results show that the modified calculation formula can improve the prediction accuracy for the gas reservoir volume factor. References | Related Articles | Metrics

Structure Controlling Factors of Oil-Gas Field Distribution in Giant Petroliferous Basins in West Siberian Province S. U. Beliaev, T. M. Hamhoeva 2006, 27 (4):  503-510.  Abstract ( 166 )   PDF (565KB) ( 132 )   Save The structure controlling factors of oil-gas distribution in giant petroliferous basins in West Siberian province were studied in detail by many scholars for over 50 years. M. Ya. Ludekaivich, F. G. Gulali, A. Ai. Kutelovich, et al. point out that the distribution of oilgas fields is related to the depressed areas or to uplift structural traps after neotectonic movement. The giant basins and depressions during long period of stable settlement are the areas for hydrocarbon generation, where the oil accumulations are in the mid and lower positions of the basins, while the gas ones in the margin of the basins. There exist 249 giant and large oil-gas fields in West Siberian province, with over 90% reserves of the total. The province is divided into three regionally geotectonic units, such as external belt, Yamarmi island-Kala regional depressed belt and Ebi regional terrace. The latter two units make up of the internal belt. The large and giant oil-gas fields found are all in these units. Also, these oil-gas fields and their reserves within the geotectonic units are researched in detail. References | Related Articles | Metrics

Geochemical Characteristics of Source Rock of Lower Cretaceous in B Basin, Central Africa Region CHEN Zhong-min, LIU Luo-fu, CHENG Ding-sheng 2006, 27 (4):  511-513.  Abstract ( 78 )   PDF (290KB) ( 161 )   Save The shale of Lower Cretaceous is uniquely verified to be source rock in B basin of Central Africa region. The geochemistry study indicates that the source rock in B basin is characterized by high organic matter abundance with II1 type of organic matter, being a good hydrocarbon source rock. Influenced by the tectonic inversion, erosion and high geothermal gradient, the present depths of hydrocarbon generation threshold are usually shallower than the normal. From NWW to SEE, the depth of threshold becomes deeper. The shale of lower Aptian stage and Barremian stage of Lower Cretaceous is the effective source rock. The oil and gas in shallow zone of slope belt in northern B basin undergo biodegradation, and have obvious relativeness with oils in deeper zone by analyzing their biological markers. It is predicted that there exist several oil kitchens in B basin. References | Related Articles | Metrics