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01 August 2011, Volume 32 Issue 4 Previous Issue    Next Issue

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Structural Pivot Zone and Its Oil-Gas Accumulation Conditions in Tarim Basin WANG Wei-guang, LV Xiu-xiang, YU Lian, CHENG Ke-nan 2011, 32 (4):  333-337.  Abstract ( 112 )   PDF (390KB) ( 304 )   Save Tarim basin has undergone multi-stage differential elevating-subsiding motion and periphery orogeny, and formed a series of structural pivot zones. Their formation is closely related to the formation and evolution of uplifts and slopes. According to the differences of forming characteristics and developing positions, the pivot zone can be divided into three types: uplift-tilted type, slope-reversed type and uplift-slope compound type. The superior hydrocarbon accumulation conditions are generally found in these types of pivot zones in adjacent source area, carbonate rock karst, weathering crust, reef-bank and karst type reservoirs, and traps are dominated by buried hill and structural-lithologic traps. With respect to sag or source areas, the pivot zones are normally in higher locations, being the pointing area of hydrocarbon migration; while with respect to the uplift top, they are in lower ones, favorable for hydrocarbon preservation. Therefore, no matter for hydrocarbon capture or preservation, the pivot zones always locate in favorable positions. In addition, the hydrocarbon distribution in pivot zones is obviously characterized by complex hydrocarbon accumulation. References | Related Articles | Metrics

New Sight about Affect of Authigenic Chlorite on Sandstone Reservoir GONG Fan-hao, BAO Zhi-dong, FAN Zheng-ping, WU Xing, LIU Li 2011, 32 (4):  338-341.  Abstract ( 114 )   PDF (456KB) ( 607 )   Save Early authigenic chlorite cementation is of significant effect on the conversion, preservation and reconstruction of primary pores, based on the casting thin section and SEM analyses of Triassic Yanchang formation of Jiyuan area in western Ordos basin. It mainly occupies primary pores, converting them into intercrystal pores of clay minerals which can impede the damages of siliceous and carbonate cements to the pores, providing pathways for late fluid reconstruction of reservoirs. Its oil-wet clay mineral attributes provide condition for late hydrocarbon accumulation in low porosity and low permeability reservoirs. Also, the sensitivity of clay minerals should be taken into consideration when developing chlorite cemented reservoirs due to chlorite’s active and easy hydrolysis chemical properties. Though previous studies show an increase in compressive resistance in chlorite cemented reservoirs, this article demonstrates high compactions after the growth of grain-coating chlorite, which means such a compressive resistance may be overstated. References | Related Articles | Metrics

Strike-Slip Faults and Their Controls on Hydrocarbon Reservoir in Middle Part of Northern Slope of Tazhong Area, Tarim Basin ZHANG Yan-ping, YANG Hai-jun, LV Xiu-xiang, LIU Hu, GAO Yan-fang, YU Hong-feng 2011, 32 (4):  342-344.  Abstract ( 96 )   PDF (311KB) ( 344 )   Save The structural characteristics of strike-slip fault in the northern slope of Tazhong area are analyzed. The controls of strike-slip faults on hydrocarbon reservoir are investigated. Study shows that there were five-period activities of the strike-slip faults in the middle of it since the Ordovician. The formation and evolution of the strike-slip faults control the vertical depth and lateral distribution pattern of the carbonate reservoir of the Lower Ordovician. The multistage active strike-slip faults serve as good channels for hydrocarbon vertical migration. In this setting, the development of carbonate reservoir is subjected to damage of some small faults, so the local structural highs at intersections of long-term active strike-slip faults and thrust faults will be the favorable areas of hydrocarbon migration and accumulation. References | Related Articles | Metrics

Genetic Types of Natural Gas in Liaodong Bay, Bohai Bay Basin TIAN Jin-qiang, ZOU Hua-yao, XU Chang-gui, ZHUANG Xin-bing, Li Nan 2011, 32 (4):  345-347.  Abstract ( 93 )   PDF (262KB) ( 256 )   Save In combination with geological background, the genetic types and origin of the found gases in the Liaodong Bay, Bohai Bay basin was studied based on the analysis data about their components, carbon isotope and light hydrocarbon. The results showed that the found gas in Liaodong Bay is mainly wet gas, and could be classified into two genetic types, which are petroliferous gas and humic-prone gas, based on δ13C2. The two genetic types are correspond to organic materials of type Ⅱ1 and type Ⅱ2. The petroliferous gas distributes in hydrocarbon fields of JZ21-1、JZ25-1 and JZ25-1S. And the humic-prone gas distributes in JZ20-2 hydrocarbon field. The petroliferous gas mainly comes from the source rocks with 0.6%~1.1% (Ro), and for the humic-prone gas comes from the ones with 1.1%~1.3% (Ro). It is concluded that the source rocks with bigger than 0.6% (Ro) in Liaodong Bay area could serve as effective gas source rocks, which suggests an optimistic prospect for gas exploration. References | Related Articles | Metrics

Distribution and Prospect of Oil Sand Resources in China XUE Cheng, FENG Qiao, TIAN Hua 2011, 32 (4):  348-350.  Abstract ( 149 )   PDF (209KB) ( 448 )   Save The oil sand resources are very abundant in China, and its reserves occupy the fifth level in the world. So it will probably be one of major fields for unconventional oil-gas resources exploration in China. The oil sand resources are found in almost all petroliferous basins, but mainly distributed in four types of basins: the tectonic compressive basins in the west, the rift basins in the east, the transitional basins in the middle and the intermountain basins in the south, among which such seven basins as Junggar, Tarim, Qiangtang, Qaidam, Songliao, Sichuan and Ordos ones have enormous oil-sand resources. They will be major areas of domestic oil sand exploration and development in the future. References | Related Articles | Metrics

Geophysical Characteristics of Shale Gas Reservoir and Its Identification Method LI Shu-guang, CHENG Bing-jie, XU Tian-ji 2011, 32 (4):  351-352.  Abstract ( 110 )   PDF (131KB) ( 377 )   Save Shale gas is the focal point of the new energy strategy in China. China’s shale gas exploration and development are just starting, and little research on such a reservoir’s geophysical features and prospecting methods is available. The shale gas reservoir is normally of features of high gamma ray, low sonic velocity, low density and high resistivity, etc., by which the reservoir can be identified. However, because of its low porosity, and gas accumulation is mainly controlled by the degree of fractures, the geophysical prospecting of shale gas is based on detecting the development level and direction of shale fractures to determine the favorable zones of shale reservoirs. This article presents the fracture-detecting and identifying methods, such as anisotropy, shear wave splitting, curvature and coherent attribute, frequencydependent AVO, etc., so that they can be as guidelines for geophysical prospecting of shale gas. References | Related Articles | Metrics

Explorative Prospect of Shale Gas of Lower Silurian in Middle-Upper Yangtze Area ZHANG Hai-quan, YU Qian, LI Yu-xi, YAN Jian-fei, LIU Wei, MEN Yu-peng, YANG Ping 2011, 32 (4):  353-355.  Abstract ( 117 )   PDF (345KB) ( 290 )   Save The Longmaxi formation of the Silurian in Middle-Upper Yangtze area is a set of high-quality hydrocarbon source developed in restricted shallow sea environment. Especially the black shale in the deposition centers of southern Sichuan, northern Sichuan, southeastern Chongqing to northern Guizhou is most developed, with big thickness and high organic matter abundance. The type of kerogen in the southern and northern Sichuan is dominated by type-I and the maturity of organic matter is in the middle-late stage of high maturity, which is dominated by generating pyrolysis gas-wet gas; The type of kerogen in the southeastern Chongqing to northern Guizhou is type-Ⅱ1 and the maturity of organic matter reaches overmature, dominated by generating dry gas. According to the organic geochemical parameters in these areas and the logging data from drilling-encountered this formation as well as the shale gas explorative practices from North America, it is suggested that Longmaxi formation of the Silurian in Middle-Upper Yangtze area has favorable conditions to form shale gas reservoirs. There exist gas logging abnormality and many of abnormal pressure zones in this formation in drilling well of Jianshen-2.These show enormous potentials for shale gas exploration of Longmaxi formation in the Middle-Upper Yangtze area. References | Related Articles | Metrics

Effect of Alkaline Diagenetic Environment of Lower Jurassic on Reservoir Property in Kuqa Depression TANG Yan-gang, LUO Jin-hai, MA Yu-jie, YANG Xian-zhang, YE Mao-lin, HE Qiao-lin 2011, 32 (4):  356-358.  Abstract ( 96 )   PDF (307KB) ( 305 )   Save Diagenetic evolution of the coal measure strata usually results in the acidic diagenetic environment, but the quartz and analcime dissolutions in the coarse clastic rocks of Ahe formation of the Lower Jurassic in Tugeerming anticlinal structural belt in eastern Kuqa depression suggest that the stronger alkaline diagenetic environment probably exists during its early stage of diagenetic evolution. Calcite cement formed in the alkaline environment holds the original interstice between the clastic grains and strengthens the compactibility-resistance of the clastic rocks. In the late stage, calcite cements are dissolved due to weathering and eluviation, and the original interstices are released and the reservoir property of Ahe formation becomes better. For this reason, the alkaline diagenetic environment in the early stage plays an important role in improving the reservoir property of Ahe clastic rocks. References | Related Articles | Metrics

3D Structural Characteristics in the Middle of Kelasu Structural Belt in Kuqa Depression BIAN Hai-guang, LI Ben-liang, JIN Jiu-qiang, TIAN Ji-qiang, CHEN Zhu-xin, GUAN Shu-wei 2011, 32 (4):  359-362.  Abstract ( 98 )   PDF (525KB) ( 386 )   Save Kelasu structural belt is located in the northern margin of Kuqa depression. Kela-1 structure and Kela-2 structure are anticlinal traps, which are under salt layer in Kumugeliemu formation of the Eogene in Kelasu structural belt. However, the drilling results are very different between the two structures. It shows that transition structure zone and structural accommodation zone exist between Kela-1 and Kela-2 structures by structural seismic interpretation and 3D structural models. The structural accommodation zone results in the complication of Kelasu anticline. At the side joint between the two structures forms transfer zone which occurs in forms of fault and fold. And anticlinal accommodation zone exists between the transfer zone and Kela-2 structure, which is the main oil-gas trap in Kela-2 structure. References | Related Articles | Metrics

Study of Shale Interlayer Sealing in Kela-2 Gas Field ZHANG Hong-guo, DAI Jun-sheng, FENG Zhen-dong, WANG Gui-wen 2011, 32 (4):  363-365.  Abstract ( 95 )   PDF (308KB) ( 281 )   Save The shale interlayers in Kela-2 gas field are penetrated or not by the fractures? The sand-shale interbedding 3D geologic model is then developed to simulate the fracture distribution through the relationship between fractural parameter and stress variation as well as extending trend of fractures in the shale. It suggests that the maximum thickness for the fractures extending in the shale is 4 meters. Hence, the faults in this field are classified into partially penetrated faults and totally penetrated faults, and the sealing effectiveness of the shale interlayers is evaluated. It is considered that the totally penetrated faults are mainly found in the southern Kela-2 gas field, particularly at the top of Baxigai formation; the partially penetrated faults mainly found in the northern, most existing in calcium shale interlayer of the Kumugeliemu group. References | Related Articles | Metrics

Oil-Gas Accumulation Phases and Fluid Inclusion Proof of Chang 4+5 Reservoir in Jiyuan Area in Ordos Basin CHEN Fang-ping, SHI Bin, LI Rong-xi, WANG Min 2011, 32 (4):  366-369.  Abstract ( 75 )   PDF (451KB) ( 247 )   Save Based on the analysis of diagenesis and formation sequence of the authigenic diagenetic minerals of Yanchang 4+5 sandstone reservoir in Jiyuan area in Ordos basin, the characteristic of fluid inclusions in diagenetic minerals and the representing hydrocarbon accumulation phases are studied. The results show that the main diageneses include compaction, pressolution, cementation, recrystallization, dissolution and fissuring process. The diagenetic minerals are authigenetic quartz, albites, dolomite, calcite and clay mineral, etc. Three different phases of hydrocarbon inclusions have been identified according to the formation time series of the host diagenetic minerals. The first phase of fluid inclusions is early-forming organic fluid inclusions, which have nothing to do with the event of hydrocarbon accumulation; the second phase of fluid inclusions is non-fluorescent asphalt inclusions, which represent the residues after damage of early oil-gas reservoirs, recording one event of hydrocarbon-accumulation reconstruction; the third phase of fluid inclusions has fluorescence characteristics of hydrocarbons absorbed in pores, distributed in albites, calcareous and siliceous cements and other late-generating cements, showing that late diagenesis occurs at the same time with charging of large amount of oil and gas, which is the record of present petroleum reservoir forming process. References | Related Articles | Metrics

Formation Mechanism of Cretaceous-Paleogene Abnormal Pressure in Dabei Area of Kuqa Depression, Tarim Basin TANG Shou-bao, GAO Feng, FAN Hong-hai, YE Zhi, JIA Li-qiang 2011, 32 (4):  370-372.  Abstract ( 77 )   PDF (227KB) ( 292 )   Save The Dabei area of Kuqa depression is an abnormal pressure well developing zone in Tarim basin. The abnormal pressure encountered by drilling occurs from the Paleogene to the Cretaceous as key strata. The detecting the abnormal pressure distribution characteristics of Paleogene-Cretaceous suggests that the tensile stress effect formed by South Tianshan tectonic movement and the developed salt rock in the key strata are two important factors for forming such an abnormal pressure in this area. Combining geological structure feature with the lithologic composition of the key strata in Kelasu structural belt, this paper presents the detailed analysis of the formation mechanism of the two great factors, respectively. References | Related Articles | Metrics

Fine Interpretation of Seismic Structures Based on Wave-Equation Numerical Simulation XIONG Xiao-jun, HE Zhen-hua, LIN Kai, XU Min 2011, 32 (4):  373-375.  Abstract ( 83 )   PDF (329KB) ( 197 )   Save To accurately identify the details of reef and other complex structures, this paper proposes a new seismic structural interpretation method based on wave-equation numerical simulation, by which the seismic numerical simulation based on one-way wave-equation in F-K domain can be made. Comparing the modeling records with practical seismic records before and after seismic migration, the original geological model of seismic structural interpretation can be successively modified. By using one-way wave-field extrapolation operators, the method not only has high computational efficiency, but also can obtain high S/N records, which is very important for the contrast of wave-field characteri stics. Moreover, adequately employing the practical records before and after seismic migration in this method, the multiple solutions of seismic structural interpretation can be effectively reduced, and thus obtaining the fine structural interpretation model. References | Related Articles | Metrics

A Simple and Practical Water-Drive Type Curve ZHOU Zhi-jun, LUO Chi-hui, LI Hui-min, YU Cheng-long 2011, 32 (4):  376-377.  Abstract ( 133 )   PDF (142KB) ( 328 )   Save During the matching of water-drive type curves, a new type curve is found, and this is a modification of N. V. Sipaqiev’s curve following transformation. After theoretical derivation, the calculation formulas in term of the new water-drive type curve are presented for prediction of the oil recovery rate and technical recoverable reserves in different water cuts. The recoverable reserves are calculated based on the actual data and the result from this curve is compared with ones from other five conventional type curves. The results show that the predicted value from this curve can give higher accuracy. References | Related Articles | Metrics

Capillary Pressure-Based Polymer Flooding Streamline Mathematic Model YU Jin-biao, WU Ming-lu, WEI Shao-lei, YAO Jun, GU Jian-wei, ZHANG Ning 2011, 32 (4):  378-381.  Abstract ( 90 )   PDF (325KB) ( 193 )   Save This paper presents a practical model for polymer flooding in which the complex chemical-physical phenomena and the capillary pressure effect are considered. And introducing transit time concept, the 3D saturation equation is decomposed into a set of 1D equations (hyperbolic equation and ellipse equation) by employing the operator splitting technique. With the 3D streamline simulator, the polymer flooding model can be calculated fast and accurately. The study shows that the little effect of capillary pressure on water flooding reservoir’ saturation (the maximum absolute error of the saturation is less than 0.02%) can be ignored, while the effect of it on polymer flooding reservoir’s saturation is larger (the maximum absolute error of the saturation is 7.5%), which should be an important factor for polymer flooding. References | Related Articles | Metrics

Numerical Simulation of Stable Production for Horizontal Well in Miao-130 Block, Jilin Oilfield ZHAO Jing 2011, 32 (4):  382-384.  Abstract ( 91 )   PDF (416KB) ( 298 )   Save In view of the features of Miao-130 reservoir in Jilin oilfield, by using Eclipse software for reservoir description and numerical simulation, this paper predicts the petrophysical property of this block, the data truly reflects the porosity, permeability, oil saturation of the reservoir and their changes. Four sets of development programs are given based on the rapid production decline and the climbing water cut, and development indices of the different programs are predicted. The results show that the Program 4 is the best for its lowest water cut, highest recovery percent of reserves and the most stable formation pressure. References | Related Articles | Metrics

Application of Porosity Prediction Based on Seismic Multiattributes to Eastern Sichuan A Gas Field ZHANG Xin-liang, HE Li-qing, WU Jun 2011, 32 (4):  385-386.  Abstract ( 88 )   PDF (264KB) ( 206 )   Save Using porosity prediction method based on seismic multiattributes can comprehensively balance individual attribute parameters so that more objectively and effectively reflect the variation of porosity, develop the relationship between the well log porosity and the seismic attribute and determine the optimal type and amount of attribute by means of multielement regression, error analysis and cross-validation techniques, and finally establish the mapping relations between the attributes and well log porosity and predict the lateral and vertical distributions of porosity. This paper first applies this method to the eastern Sichuan A gas field and predicts the porosity distribution of its super-dense sandstone reservoir. And good result is gained. References | Related Articles | Metrics

A New Method for Predicting Volumetric Sweep Efficiency of Water-Drive Oilfields WANG Bo, ZUO Song-lin, LIU Lang, JIAO Yu-wei 2011, 32 (4):  387-389.  Abstract ( 91 )   PDF (210KB) ( 334 )   Save Water-drive volumetric sweep efficiency is an important parameter to evaluate the production performance and development adjust-ment effect. Based on the fluid mechanics theory and Buckley-Leverett equation, combined with the relationship between oil-water permeability ratio and water saturation, a new method for predicting volumetric sweep efficiency and evaluating the development adjustment effect on water-drive recovery is presented in this paper. The case study and application indicate that this method is reasonable, effective and feasible. References | Related Articles | Metrics

Application of 3D Fine Interpretation Technique of Seismic Structures in Xiaoji Oilfield ZHU Cong-jun, XIA Guo-chao, ZHENG Tai-shan, SONG Jin-fu, XU Jing 2011, 32 (4):  390-391.  Abstract ( 98 )   PDF (212KB) ( 193 )   Save Xiaoji oilfield in the southern Huanghua depression is a typical complex reservoir characterized by high exploration-development level, multiple oil-bearing layers, more faults and complex structure, so it is of greater potentials for rolling exploration. Based on the fine layer calibration, using the 3D fine interpretation techniques of seismic structure, such as multi-way profile display, local magnification of seismic profile, fault test and analysis, chair-like display, time-slicing and 3D visualization, etc., the structure in Xiaoji oilfield has been fine interpreted, finding out a number of new oil-bearing fault blocks, effectively bringing about the incremental reserves and production in this old oilfield. References | Related Articles | Metrics

Optimization of Well Patterns in Extra-Low Permeability Fault-Block Reservoirs by Numerical Simulation QI Ya-dong, YANG Zheng-ming, YAN Jun, LUO Ying, YANG Peng 2011, 32 (4):  392-395.  Abstract ( 82 )   PDF (411KB) ( 215 )   Save Arrangement of well pattern in a extra-low permeability fault-block reservoir is affected by its geometry and nonlinear flow features. Taking Hua-17 block in Jiangsu oilfield as an example, different well patterns are designed in view of its different geometries, and the nonlinear flow features are considered. Then the development effect of each well pattern is evaluated using the nonlinear flow numerical simulation software. The results show that for the banding-like fault block reservoirs that two rows of vertical wells can be arranged, the optimal pattern is the one with the injection wells arranged opposite every second production well; for the small-size banding reservoirs, a horizontal production well and a vertical injection well can be arranged, and the optimal location of the vertical well is the periphery of the horizontal well's hoe; for the triangular reservoirs which can arrange a few vertical wells, the injection well should be arranged outside the production well line to achieve the optimal development effect. This research provides a new method for well pattern optimization of extra-low permeability fault block reservoirs. References | Related Articles | Metrics

Design of Fault-Bypassing Horizontal Well in BottomWater and Fault-Block Reservoir———An example from Well CHW05 of Cai-10 wellarea in Cainan oilfield TANG Lin, ZHANG Yan-mei, JI Wei-min, TIAN Bo 2011, 32 (4):  396-398.  Abstract ( 103 )   PDF (252KB) ( 268 )   Save Based on the status and distribution characteristics of the remaining oil and reserves of Sangonghe reservoir in Cainan oilfield, the block suitable for drilling horizontal well is selected, the feasibility of the horizontal well is demonstrated and the well location design is opti mized. Through real-time control by means of composite log, cutting log and 3D geologic model and other technical methods, the operation for bypassing the fault is realized and higher oil layer drill-encountering rate is achieved successfully. And the productivity by horizontal drilling process after putting into production meets the demand of the project design, obtaining good economic efficiency. The successful implementa tion of this scheme opens up wider spaces for developing the remaining oil in bottom water fault-block reservoirs in Cainan oilfield. References | Related Articles | Metrics

Chemical Characteristics and Geological Significance of Formation Water of He-8 Member in Western Sulige Gas Field, Ordos Basin JIANG Wen-juan, FENG Qiao, LI Ying-li, HAN Bo, WANG Qian-yao, ZHOU Shu-chang, ZHANG Hong-mei 2011, 32 (4):  399-401.  Abstract ( 86 )   PDF (382KB) ( 341 )   Save The He-8 member of Shihezi formation in Sulige gas field is the main production zone, with the formation water salinity of 0.79~99.87g/L and CaCl2 water type. It is found that there exists the independent distribution of gas layer or water layer in this member, and besides, there are 3 types of distribution features, including gas/water layer, interbedded gas/water layer and same gas/water layer in sand body of one interval. Through gas test data and formation water analyses from 119 wells, the formation water salinity, the ions concentration ratio distribution and metamorphosed degree are drawn. Finally, the relationship between the formation water property and distribution and the natural gas enrichment is determined, and the favorable areas with gas exploration potentials are predicted. References | Related Articles | Metrics

Multiscale Inversion Algorithm for Seismic Residual Static Correction and Its Application LI Li, CHEN Xiu-juan, JING Xi-li 2011, 32 (4):  402-405.  Abstract ( 81 )   PDF (516KB) ( 285 )   Save The conventional inversion method for seismic residual static correction is analyzed, and the reason for it is found. The quality of model trace is related to the apparent cycle of seismic wave. As a relative quantity, when the static correction quantity is larger than a half or more of the apparent cycle, the model trace's quality becomes poor, emerging the cyclic-skip phenomenon using linear inversion method. According to this, the multiscale residual static correction method based on model trace is developed, by which the large static correction quantity issue under small scale can be converted into the small static correction quantity issue under large scale, thus avoiding the appearance of cyclic-skip phenomenon. The low accuracy of the large scale static correction can be considered at the same time. So the large static correction quantity calculation could then be realized by using the multiscale inversion algorithm. The case study shows that this method is effective, efficient and convenient for use. References | Related Articles | Metrics

Early Application Effectiveness of Deep Profile-Controlling Technology to Badaowan Reservoir in D-12 Well Area in Cainan Oilfield GONG Zhao-bo, QIAO Yue-hua, LIU Qing-ming, ZHAO Jun, FU Guang-hui, BAI Xue, ZHA Ke-jian 2011, 32 (4):  406-408.  Abstract ( 87 )   PDF (205KB) ( 272 )   Save The Badaowan reservoir in D-12 well area in Cainan oilfield is characterized by serious heterogeneity, developed big pores, rapid climbing water cut and poor response of small dose profile control, etc. This paper puts forward a managing idea of early applicating deep profile controlling technology and conducting overall deep profile control in this area. A jel system for deep profiel control dominated by polyacrylamide that is more suitable for this area is developed. In order to enhance plugging capacity to bigger water breakthrough channels, the solid grains are added into the system. In 2010, the profile controls were conducted in four well groups in D-12 well area, then averaging injection pressure in injection wells rises by 1.85 MPa, daily oil increases from 2.0 t to 3.1 t, composit water cut decreases from 57.8% to 56.6%, and present cumulative incremental oil amounts to 1 063 t in the four well groups. References | Related Articles | Metrics

Calculation Method of Natural Depletion Oil Recovery for Micro-fractured Low Permeability Reservoirs ZHANG Xiao-liang, ZHANG Jin-qing 2011, 32 (4):  409-411.  Abstract ( 83 )   PDF (217KB) ( 315 )   Save The conventional depletion oil recovery calculation method based on Darcy equation has certain limitations to fractured low-permeability reservoirs due to the strong anisotropy caused by the natural micro-fracture and the threshold pressure gradient of the matrix. A new depletion oil recovery calculation method is proposed, which can take both the reservoir anisotropy and the non-Darcy flow in matrix into consideration. The study indicates that the natural depletion oil recovery of fractured low-permeability reservoirs within the ultimate drainage radius is only one third of that calculated with the conventional method. The non-Darcy flow oil production decline and the field application are analyzed to verify the calculation rationality, and the calculation result has a good agreement with that of actual low-permeability reservoir development. References | Related Articles | Metrics

Fracturing Numerical Simulation Research on Wuwu Fault Block Development inWunan Oilfield YAN Xue-mei, XU Yun, JIANG Jian-fang, WANG Xin, JIANG Ting-xue, TIAN Zhu-hong, WANG Teng-fei 2011, 32 (4):  412-414.  Abstract ( 81 )   PDF (293KB) ( 202 )   Save By using Eclipse software and numerical simulation method, The $N^{1}_{2}$ reservoir of Wuwu fault block in Wunan oilfield is simulated. Under isotropic condition of the matrix permeability, three well patterns such as five-spot areal well pattern, inverted nine-spot rhombic and square well pattern are compared for getting the effects of the fracturing fracture’s penetration rates on production performances. At the result, five-spot areal well pattern is recommended for this block, and the ratio of well spacing to well row distance of 2 and well spacing of 350~400 m will be most suitable. References | Related Articles | Metrics

Application of R/S Analysis to Fractural Prediction in H2 Reservoir in Huoshaoshan Field WANG Li-rui, ZHAO Guo-chun, WANG Guo-xian, WU Cheng-mei 2011, 32 (4):  415-417.  Abstract ( 92 )   PDF (284KB) ( 280 )   Save The H2 reservoir of Huoshaoshan oilfield in eastern Junggar basin is characterized by extremely low matrix permeability and relatively developed fractures. Over the years, the various data are taken for research and further fine description of the fractural features. Starting from the well log data, by means of R/S analysis, the fractures in H2 reservoir are studied. The R/S values of more than 300 wells are calculated one by one, by which the R/S curves of this reservoir are drawn. Also, the comparisons of these with real core sample, EMS, EMI fracture well logs as well as the production performances from producers and injectors are conducted. The results show a high degree of agreement, indicating fractal theory can be used for fractural analysis and study. References | Related Articles | Metrics

Application of Merging Pre-Stack Time Migration Technique in Western Sag of Liaohe Basin JI Zhan-zhen, LIU Shi-guang, ZHANG Shu-mei, GAO Shu-sheng, YU Juan 2011, 32 (4):  418-420.  Abstract ( 107 )   PDF (450KB) ( 315 )   Save According to the features of seismic data in study area, the technical study of large-scale merging pre-stack time migration (PSTM) is made and the signal-to-noise ratio of pre-stack is improved. The techniques of amplitude adjustment in time-frequency-space domain, amplitude normalization, signature shaping and space-variant deconvolution are developed to improve imaging quality and lateral resolution. The above techniques are applied to 13 blocks, which realize seamless joint of the data, of which 25 favorable traps with an area of 301.6 km2 have been found and determined in four major blocks and 17 exploratory wells have been designed and arranged. References | Related Articles | Metrics

Application of Empirical Formula for Pseudo-Pressure Calculation to Cai-31 Gas Reservoir in Cainan Oilfield CHEN Yong, CHEN Chen, CAO Jian, LUO Gang 2011, 32 (4):  421-423.  Abstract ( 113 )   PDF (243KB) ( 353 )   Save In accurate calculation of gas viscosity and compressibility factor z, an empirical formula for the pseudo-pressure calculation of real gas at a constant temperature is presented, and the converted curves from pressure to pseudo-pressure and the single well productivity equation for deliverability test are given. The case study in Cai-31 gas reservoir shows that its gas well performance prediction by these formula and equation is better in effectiveness. References | Related Articles | Metrics

Using Unsteady Well Testing Data to Get Saturation Pressure CAO Jian, CHEN Yong, CHEN Chen, LUO Gang 2011, 32 (4):  424-425.  Abstract ( 96 )   PDF (158KB) ( 274 )   Save Using build-up pressure curves to get saturation pressure of unsaturated reservoirs with low formation-saturation pressure difference in different types of reservoirs can not only make up the defects of limited PVT data and rigorous condition for sampling, but also can expand the applied range of build-up pressure curves. The application of this method to SN block in SX oilfield has obtained satisfactory result. References | Related Articles | Metrics

Application of Beaming Perforation Technology to Low-Porosity and Low-Permeability Reservoir Development BI Sheng-yu, LIU Gong-hui, ZHOU Chang-hong, LI Jun 2011, 32 (4):  426-428.  Abstract ( 125 )   PDF (292KB) ( 250 )   Save The theory of the beaming perforation technology suitable for low-porosity and low-permeability reservoirs is introduced, and the actual well is taken as example to make the optimizing design of beaming perforation. Following implementation of this design, the anticipated producing effect is obtained, which indicates that the beaming perforation technology matched the reasonable perforating design can increase and optimize the productivity of such reservoirs. It is suggested that popularization and application of this technology will be helpful to efficient development of domestic low-porosity and low-permeability reservoirs. References | Related Articles | Metrics

Basalt Feature and Bit Type Selection in Malang Sag WU Hui-mei, LOU Yi-shan, ZHANG Yong, LIU Yun-he 2011, 32 (4):  429-430.  Abstract ( 174 )   PDF (222KB) ( 347 )   Save The main lithology of the igneous rocks under the Permian in Malang sag is basalt with the characteristics of strong abrasion resistance, low drillability and low drilling rate. This paper tests the drillability of the cores from the field, develops rock drillability model, computes the drillability grade of cone bit and PDC bit and optimizes the bit according to the bit structural features. The results indicate that in light of the basalt strata under Permian, using recommended bit has increased the mechanical drilling rate by 50% compared with other bits, shortened the drilling cycle, and attained the aim of excellent and fast drilling. References | Related Articles | Metrics

Segmentation of Sub-Andean Retro-Arc Foreland Basins in Western South America JU Liang, ZHANG Guang-ya, WEN Zhi-xin, WANG Wei-guang 2011, 32 (4):  431-434.  Abstract ( 172 )   PDF (580KB) ( 780 )   Save Sub-Andean retro-arc foreland basins in the western margin of South America are important petroleum accumulation and production zones, and develop in three different tectonic settings: evolvement of Caribbean plate superimposed Andean-type foreland compressive deformation in the north; Sub-Andean foreland basins were in long-term the Gondwana continental marginal setting, subsequently subducted by oceanic plate and thrusted by Andean orogenesis in the middle; the shapes and evolvement of basins in Patagonia were more influenced by Gondwana breakup and opening of Atlantic in the south. Based on the evolvements and petroleum characteristics, the sub-Andean retro-arc foreland basins in the western margin of South America could be divided into 6 segments. References | Related Articles | Metrics

Heavy Mineral Assemblage and Provenance Analysis of Eocene in Shwebo Basin, Myanmar XIE Nan, ZHAO Ru, ZHU Guang-hui 2011, 32 (4):  435-438.  Abstract ( 122 )   PDF (332KB) ( 447 )   Save Based on the thin-section identification and the heavy mineral analysis, including the clastic component observation and relative percent content estimation as well as the ZTR index feature, it is suggested that the sediments (clastic rocks) of the Eocene in Shwebo basin in Myanmar are seldom affected by the volcanic facies provenance from Shan plateau in eastern Shwebo basin, which are characterized by a short-distance transportation. Based on the types of clastics and heavy mineral associations, the parent rocks of Block X are of two types: mica schist and mica quartz schist of metamorphic rocks, intermediate-acid hypabyssal intrusive rocks. References | Related Articles | Metrics

Application of Horizontal Wells to HighWater Cut Fields in Block 1/2/4, Sudan DONG Jun-chang, BAI Feng-han 2011, 32 (4):  439-441.  Abstract ( 108 )   PDF (224KB) ( 296 )   Save The oil fields in block 1/2/4 in Sudan have entered into a high water cut period. This paper reviews the effectiveness and experiences from horizontal drilling process on the basis of the applicability research of horizontal well technology in block 1/2/4. It suggests that the key of adopting horizontal well to development of the high water cut reservoir is in clear recognition of its remaining oil distribution. For the heavy oil and bottom water reservoir and the top poor oil layer of positive rhythm reservoir are more suitable for recovery by horizontal drilling process. During the development process, the position and length of horizontal well interval in the reservoirs should be designed reasonably, at the same time, the research of the water monitoring and controlling treatment should be strengthened. These practical experiences will be as a reference to the horizontal well application in high water cut oil field. References | Related Articles | Metrics