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01 June 2004, Volume 25 Issue 3 Previous Issue    Next Issue

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Tibet-A New Take-Over Region for Petroleum Resources of 21st Century in West China QIU Dong-zhou 2004, 25 (3):  233-239.  Abstract ( 89 )   PDF (802KB) ( 299 )   Save This paper discusses the petroliferous property of Tibet region in light of characteristics of its regional geological structure andpetroleum geology with analysis of its petroliferous areas and basins. In view of the unique feature in petroleum accumulation condition,Tibet region can be divided into five petroliferous areas such as Qaidam (margin), Bayankelahan,Qiangtang-Changdu, Gondis andHimalayan ones. As for petroleum resource assessment of their complex structural areas, this paper proposes a concept of petroliferousbody composed of basin, residual basin, remnant structural mass and relic deposit, which is regarded as the basic unit for petroleumresource assessment, the target for oil-gas exploration and the core of evaluation. In addition, this paper makes an analysis and estimationof hydrocarbon-generated amount,potential resource amount in main basins of Tibet. The result shows that the petroleum resourcesamount to 9 billion tons, revealing its bright future for exploration, in which Qiangtang basin should be selected as an optimal body, andother basins like Cuole, Biru, Changdu and Gonba-Riding could be as prospective bodies. References | Related Articles | Metrics

Noble Gas Isotopic Compositions in Mantle Fluids and Mantle-Derived Natural Gas Pool WU Mao-bing*, LIU Chun-yan2, ZHOU Hui-wu2 2004, 25 (3):  240-243.  Abstract ( 96 )   PDF (219KB) ( 356 )   Save Noble gas isotopic compositions in mantle fluids are associated with their tectonic settings and magmation in deep mantle. For'He/*He ratio, the mid-oceanic basalts range 8~ 10R; hot-spot mantle source is over 30R,; back-arc basinal basalts and mantle xenolithsvary widely frome 5Ra to 22R,; terrestrial mantle xenoliths are 3~ 10R; He component in diamonds is not only primitively captured, but al-so invaded from the outside. In rift basins of East China occurs mantle source gas pool with 3He/'He ratio of 2.7~6.4R,, and such mantlegases migration and accumulation are related to the regional deep faulting. In general, 40Ar/·*Ar value in mantle source is around 350,and increases with the feeding of continental crust materials. In mantle contains solar Ne, and samples reveal the same ratio of Ne and Xeisotopic compositions with atmospheric Ne/Xe ratio. Also, it is found out that Ne and Xe isotopic compositions appear excess phe-nomenon compared to the atmospheric ones. Study shows that they are characterized by nuclear origins. References | Related Articles | Metrics

Restudy on the Structural Unit Div ision and Petroliferous Potentials in Qiangtang Basin GUO Zu-jun*, WANG Yi-chang2, YE He-Fei* 2004, 25 (3):  244-247.  Abstract ( 109 )   PDF (937KB) ( 329 )   Save Based on the combination of surface geological data and geophysical data, the basic framework of Qiangtang basin can be sub-divided into four primary units, seven secondary units and a few third units. It is pointed out that the eastern North Qiangtang depressionand the eastern South Qiangtang depression are favorable source areas; Sebei low swell and Long 'enigu reservoir could be major prospect-ing areas, and Dazuoma faulted-anticline is the most significant structure for petroleum exploration. References | Related Articles | Metrics

The Detailed F ramework Model Development for Fan-Delta Front Reservoir in Shuanghe Oil Field CHEN Cheng, SUN Yi-mei 2004, 25 (3):  248-250.  Abstract ( 83 )   PDF (595KB) ( 204 )   Save The geometrical scale and distribution of a reservoir's microfacies sand body are the bases to analyze the regulation of in-situoil and water flow and adjustment for proper well patterns. This paper proposes a method to build the detailed framework model for fan-delta front reservoir based on the geological features of Shuanghe oil field, in order to meet the requirements of predicting the remainingoil distribution during the late period of development. Before setting up a detailed framework, the geological knowledge such as the depo-sitional mechanism, the distinguishable criterion, the scale of microfacies sandbody, the channel density and the occurring conditions ofspecific sandbodies, etc. are needed to determine the borders of microfacies sandbodies and interpolation for them. In this paper, thewidth-thickness relationship of microfacies sandbodies and the quantitative description of the channel development are presented, and theframework model for Layer-2 in oil member IlV is developed. Such a method could be significant for the detailed reservoir description ofother analogous oilfields. References | Related Articles | Metrics

Sidimentary Facies Classification of Turbidite of Upper Part of the Shasi Member in Bonan Sag, Shengli Oilfield WU Fu-qiang 2004, 25 (3):  251-253.  Abstract ( 78 )   PDF (414KB) ( 355 )   Save This paper presents briefly the geological features,describes the turbidite and its sequences and styles and studies the sedi-mentary facies and microfacies of the upper part of the Shasi member in six wells in Bonan sag. It is demonstrated from lithology of deepwater, rock structure of density flow origin, grain distribution of turbidite origin, seismic and well logging responses and proper formingconditions that under the background of the deep lacustrine and semideep lacustrine facies deposits develops sublacustrine fan and farglutinite lens. . References | Related Articles | Metrics

Structural Styles and Deep Gas Accumulation in Xujiaweizi Fault Depression of Songliao Basin LIU Xue-feng1,2, MENG Ling-kui* 2004, 25 (3):  254-258.  Abstract ( 91 )   PDF (2140KB) ( 243 )   Save Based on the structural styles classification of J.D. Lowell, detailed classification and study of structural styles in the studiedarea are made, and possible natural gas traps in these structural styles are investigated. Considering whether the basement being involvedor not, the structural styles could be divided into two major types like basement involvement and caprock detachment. According to thedifferent stress env ironments and the different structural assemblages, nine basic structural styles are identified. The study shows that de-velopment of the structural styles is primarily controlled by the compresso-shear stress field with near S-N orientation occurred in faultdepression stage, while the late compressive stress field with NW-SE orientation only has a minor controlling process. Each of structural .styles has its control to the gas accumulation in some degree. Among them, the anticline, anticline-faulted traps developed in assemblageof half graben-like and fault convex controlled by low angle boundary fault, syn-sedimentary compressive anticline, thrust-fold assemblage,fault-bended anticline and its overlaying syn-sedimentary anticline are in favour of natural gas accumulation in Xujiaweizi area of north-ern Songliao basin. References | Related Articles | Metrics

Geochemical Characteristics and Genetic Type of Natural Gas in Jiuxi Depression GAO Bo*, CHENG Ke-ming2, XIONG Ying2, YANG Zhi-ming3 2004, 25 (3):  259-261.  Abstract ( 76 )   PDF (343KB) ( 365 )   Save The systematic research is made on the geochemical characteristics of natural gas in Jiuxi depression. The result shows thatcomposition of the gas is dominated by hydrocarbon gas which accounts for 91 .82%~99.22%, averaging 75.81%, composed of methane(68.85%~85. l3%, 75.81% in average) and heavy hydrocarbons (20.34% in average) and C1/C1-5 ratio ranges from 0.75 to 0.87, belongingto typical wet gas. The non-hydrocarbon gas is dominated by CO, accounting for 0.78%~8.18%, averaging 3.85%. The δ13C1value rangesfrom-45.3%o to-40.2%o, δ13C2 value from-31. 1%o to-28.4%.(-30.27%0 in average) andδ13C2value from-28.6%o to-26.9%o (-27.6%o inaverage), i.e.δ13C3, which belongs to the ty pical petroliferous gas. References | Related Articles | Metrics

Application of Multivariate Statistical Analysis to Oil-Source Correlation LI Zhen-guang, LI Jing-kun, SONG Gui-xia 2004, 25 (3):  262-263.  Abstract ( 76 )   PDF (252KB) ( 255 )   Save Analysis of 34 crude samples from Heidimiao formation in northern Songliao basin is made with the cluster analysis method.The results show that the crude oil can be divided into two types and three subtypes.From saturated hydrocarbon chromatographicalanalysis, Type-I oil has the top peak intensity in nC14+nC21, Type-IIa takes second, and Type-Ib assumes the lowest; in range ofnC25~nC37, Type II-b predominates instead of Type-IIa, while Type-I assumes the lowest. For Type-I oil, it is dominated by ΣnC21-/ΣnC22+ ratio 1and nC21+nC22. In addition, the factor analysis method is adopted to make source correlation of 34 Heidimiao crude samples and 109mudstone samples. It is shown that Type-I crude primarily originated in Q-I member source rock, while Type-II in N-1 source rock, andN-2 source rock has some contributions to it. References | Related Articles | Metrics

Critical Point Analysis of Hydrocarbon Recovering Coefficients WU Xin-song1,2, HAN De-xin*, ZHANG Xiang-zhong* 2004, 25 (3):  264-266.  Abstract ( 112 )   PDF (559KB) ( 240 )   Save How to accurately recover the losing hydrocarbon by pyrolysis geochemistry logging is a crucial step for reservoir fluid-produc-ing evaluation. It is very difficult to determine the recovering coefficients due to lack or less integrity of data in real core analysis. Fordealing with this problem, a new method called critical point analysis is proposed in this paper. It can be used to find the critical point bydrawing the scatter plot of hydrocarbon composition content versus the ratio of the light/ weight hydrocarbon composition contents, andthen to calculate the recovering coefficient by contrasting the py rolysis parameters of critical point for different types of fluid samples.This method can be not only explained reasonably in terms of theory, but also be reliable for practical application. References | Related Articles | Metrics

Variation of Biomarker Parameters in the Mixed Immature and Mature Oils SONG Ning1,2, LIN Chun-ming*, CHEN Li-ping2 2004, 25 (3):  267-269.  Abstract ( 99 )   PDF (639KB) ( 225 )   Save An immature oil sample from Tang-6 Well and a mature oil sample from Sha-7 Well in Subei basin are selected and mixedeach other with different ratios so as to investigate changes between biomarker indices.The saturated hydrocarbon separated from themixed samples is analyzed by GC and GC-MS, respectively. The study shows that different changes occur in mixed sample indices andmixed ratio, e.g. n-alkanes and terpenes parameters assume linear changes approximately, but others (e.g. steranes) assume nonlinearones. The reasons caused are that the concentration of steranes, terpenes and n-alkanes in the immature oil differs from that in the matureoil. It is indicated from estimation that when the difference of the concentration among them are big, they appear in nonlinear change andtend toward increasing concentration, and this trend doesn't disappear until compounds of low concentration account for absolute predom-ination. The phenomenon is called the allocation principle of concentration-feature contribution ratio in the mixed oils. The results showthat the mixed ratio is not only dependent upon biomarker indices, but also, it is more important to make clear the original concentrationsrelated to these compounds. The "immature oil" pre-recognized from steranes maturity parameters could be the mixed oil dominated by themature oil. References | Related Articles | Metrics

The Modeling of Pressure Field Evolution History in Damintun Sag, Liaohe Basin SHI Jian-nan*, JIANG Jian-qun2, LI Ming-kui2 2004, 25 (3):  270-273.  Abstract ( 83 )   PDF (675KB) ( 229 )   Save The pressure field evolution in Damintun Sag is modeled with Basin-2 simulator. The result indicates that overpressure preva-lently occurs in this area, which is characterized by vertical extension and deep expansion, and faults are important to control the accu-mulation and release of overpressure. The result is consistent with remaining pressure distribution of equivalent depth method, whichproves the reliability of the modeling result by using Basin-2 simulator. The evolution of overpressure is generally followed by such rule ofoverpressure changes as zero, steeply growing, gently increasing, up to the top, declining and the lowest, which is well matched with thedepressed process of this area. It is indicated that the overpressure greatly affects the generation, migration and accumulation of hydrocar-bons in it. In view of the distribution characteristics of overpressure in different strata, it is suggested that Late EgS, and Dongy ing forma-tion are the main hydrocarbon migration period and the traps in low-value area of residual pressure are favorable petroleum accumulationareas to be regarded as important domains for oil-gas exploration. References | Related Articles | Metrics

Well Log Evaluation of Fractured Reservoir of Xiagou Formation in Kulongshan Reservoir WU Hui, TAN Xiu-zhong, SUN Wan-gao, ZENG Li-gang, HU Xiao-yong 2004, 25 (3):  274-276.  Abstract ( 97 )   PDF (3646KB) ( 144 )   Save This paper makes a study of formation occurrence and fracture character of glutenite reservoir of Xiagou formation in Qingxioilfield using well log, mud logging and lab analysis data; a establishment of low limit standard of rock electrical property for the fracturedreservoir using dual laterolog,gamma ray log and tri-porosity logging data; a recognition of the vertical fracture-developed section andfractural occurence for it using dip log, fl-bore imaging microlog and dipole shear imaging sonic logging; finally, makes a developmentof interpretation model for parameters such as porosity, oil saturation, etc. using gamma ray log, dual laterolog data. It is believed thatthese studies provide reliable basis for evaluation of glutenite fractured reservoir in this area. References | Related Articles | Metrics

Reservoir Characteristics of Difficult-to-Produce Area in L Oil Pool, Ya erxia Oilfield LI Feng, WANG Wei, CHEN Xiao-xue 2004, 25 (3):  277-279.  Abstract ( 104 )   PDF (4622KB) ( 177 )   Save In view of reservoir feature in difficult-to-produce area of L oil pool in Ya 'erxia oilfield, this paper analyzes the structural style,sedimentary character,formation testing and production test fects, based on which establishes standards for reservoir classification andnet pay thickness recognition, describes the reservoir heterogeneity, and quantitatively determines the porosity, permeability, initial oilsaturation, net pay thickness and reservoir sensitivity, by using conventional study method for sandstone reservoir and re-interpretation ofwell test data. The sound bases could be as a guide for effective development of this dfficult-to-produce area. References | Related Articles | Metrics

Velocity Field and Its Characteristics in Kulongshan Overthrust Nappe : FANG Chen, SUN W an-gao, TANG Guang-hua, YANG Ke-rong 2004, 25 (3):  280-282.  Abstract ( 82 )   PDF (638KB) ( 247 )   Save By horizon-controlled method, the velocity fields of Kulongshan and Jinhaizi 3-D areas are mapped,the characteristics ofvertical and transversial distribution of velocity are discussed. The analyzed result shows that distinct velocity layering feature occurs invertical direction, and velocity reversion is found in near surface-shallow zone and mid-deep zone; the velocity of overthrust nappe is ofclear block feature in lateral direction; the variation of lateral velocity tends to grow ing from north to south, with gradient of north-low andsouth-high; the contour of velocity assumes distributing along the north-west direction roughly, and there are abnormal-velocity regionsfor these two 3-D areas. It is shown that differences in deep-shallow lithology, thickness and compaction degrees are the essential causesfor the velocity anomaly in these areas. References | Related Articles | Metrics

Tearing Fault and Petroleum Accumulation in Kulongshan area, Jiuquan Basin XIAO Wen-hua, YOU Cheng-cai, TAN Xiu-zhong, REN Xiao-hong, YANG Hong-mei 2004, 25 (3):  283-285.  Abstract ( 112 )   PDF (5193KB) ( 206 )   Save Kulongshan overthrust nappe is located in west of nothern margin of Qilíanshan mountain. It is a faulted basin in Mesozoicand a foreland in Cenozoic. In its Qingxi depression is found fractured reservoirs, In order to make elear the oil-gas enrichment , this paperdiscusses the effect of tearing faults in overthrust nappe on oil-gas accumulation by means of the analysis of structural faults and theirdistinct oil-gas distribution. ht is pointed out thal il is N-E tearing fault that controls the distribution of open frachral bel, which could behigh-yielding block. References | Related Articles | Metrics

Prediction of Lower Cretaceous Reservoir of Qingxi Sag in Jiuquan Basin SUN Cheng-tian, WANG Rong, ZHOU Zai-hua, LI Tao 2004, 25 (3):  286-287.  Abstract ( 82 )   PDF (3229KB) ( 212 )   Save In Qingxi sag of Jiuquan basin developed mud-dolomites (argillaceous dolomite, dolomitic shale, dolomite), mudstone andglutenite,ete. Analysis of such an assemblage of lithology shows that velocity differences among mud-dolomites and between mud-dolomites and mudstone are small, with similar responses of well logging and few contrasts of seismic reflection events. According tothese features, relying on available technologies, the method for reservoir prediction that can be used to deal with practical issues ispresented, by which seismic inversion, geologic statistical analysis and lithology prediction are made in Qingxi sag with 3-D data of highresolution and signal/noise ratio, And good effects are obtained from them. References | Related Articles | Metrics

Bedded Tuff Reservoir in Qingxi Oilfield LI Jun, WANG Wei, WANG Shu-xun 2004, 25 (3):  288-290.  Abstract ( 85 )   PDF (4880KB) ( 169 )   Save Qingxi oilfield in Jiuquan basin is found in Xiagou reservoir of Lower Cretaceous, mainly composed of bedded-tuffaceouscarbonate and bedded tuffaceous glutenite.It is the tuffaceous presence that not only improve the reservoir spaces, but also in favor offorming various fractures which provide sites for hydrocarbon accumulation, The sites include secondary vuggy intercrystal pore, matrixmicropore and secondary intragranular dissolved pore that shaped by dissolution,matasomatism and epigenesis as well a8 drainagestructure shaped by compaction, in which the fracture has a great effect on permeability and movable fluid saturation rather than porosity References | Related Articles | Metrics

The Reservoir and Sedimentary Characteristics in Xiagou Formation of Lower Cretaceous in Qingnan Hypo-Sag, Jiuquan basin YANG Ke-rong, ZHAO Qian-ping, A Xiao-yun 2004, 25 (3):  291-293.  Abstract ( 112 )   PDF (493KB) ( 261 )   Save There exist fan delta and lacustrine deposits developed in Xiagou formation of lower Cretaceous in Qingnan Hy po-sag, Jiuquanbasin. In this paper, the sedimentary features of single-well facies, palaeo-source and palaeo-current are studied, the vertical and .transversal distributions of the reservoir rock facies are described, and the distribution and main characteristics of favorable reservoir rockfacies,lithology which are gray conglomerate developed in fan delta front and pelitic dolomite developed in semi-deep lake aresummarized. References | Related Articles | Metrics

Hydrodynamic System of Fractured Reservoir with Bottom Water in I ong-5 Block,Qingxi Oilfield ZHANG Hu-jun, LI Hong-biao, HU Ling-zhi, YUAN Guang-xu 2004, 25 (3):  294-296.  Abstract ( 83 )   PDF (376KB) ( 190 )   Save Qingxi oilfield, a major area for rolling exploration and development, accounts for 56 percent of the total annual production of Yumen Oilfield Company. Long-5 block, a major oil producing region, is a relatively independent and deeply fractured conglomerate reservoir with bottom water.Up to now, there are 3 wells which yields over 100 t/d of oil have been watered-out seriously for bottom-water breakthrough, threatening the normal development of this field. This paper makes a preliminary investigation of the hydrody namicsystem, water-invaded mechanism and watered-out controlling factors, based on material balance equation integrated with field productiondata. It is pointed out that the bottom water invades into payzones mainly along high-angle and high-permeability fractures; the free-waterrecovery phase is primarily subjected to vertical permeability and depth of fractural extension, which provide realistic basis for stable oilproduction and water control in future. References | Related Articles | Metrics

Productivity Analysis of Commingled Production in Circle-Sealing Reservoir with Infinite Conductive Vertical Fractures LIU Peng-cheng*, WANG Xiao-dong*, HOU Xiao-chun*, LI Fan-hua2, DENG Hong-wen* 2004, 25 (3):  297-300.  Abstract ( 106 )   PDF (6194KB) ( 214 )   Save Hydraulic fracturing is a technology well applied to development of low permeability or damaged formation. This paper presentsthe commingled produetion of circle-sealing, n-zone and heterogeneous reservoir with infinite conductive vertical fractures, in which in-cludes conditions such as no interfacial crosflow, equal or unequal drainage radius and initial pressures for different zones, as well asmethods and formulae for calculating the wellbore pressure and individual bedding flow rate at constant production rate and certain pres-sure in vertical fracture wells for an oilfield development.Taking two-zone fractured reservoir as an example,and adopting Stehfest numeri-cal inversion method, the changes of bedding flow rate under the conditions of the constant pressure and production in an oil well with in-finite conductive vertical fractures are estimated, and the well productivity and its affected factors are analyzed and discussed.Thismethod can be as a guide for the alloation of production and injection rates, performance prediction and development adjustment for thistype of reservoirs. References | Related Articles | Metrics

On Relative Permeability Curves and Production Characteristics of Reservoirs WANG Guo-xian, XIE Jian-yong, WAN Wen-sheng, SHI Yan, LIU Yan-hong, LIU Bao-zben, NAN Hui 2004, 25 (3):  301-304.  Abstract ( 121 )   PDF (8296KB) ( 39 )   Save The relative permeability curves to oil and water can exhibit the pore structural variation, oil and water distribution and oil andwater movement and production characters in reservoirs during water flooding. Although there exist various relative permeability curves tooil and water, they can be divided into such five types from actual field data as upward concave, straight line, downward concave, upwardconvex and chair-shaped types to water phase. These types of curves are of contrast shape, obvious feature and different production char-acters. Accordingly, the reservoirs with above relative permeability characteristics can be classified into five types: three pore flow systemswith moderate-high permeability, ow permeability and low permeability and water sensibility, and two fracture flow systems with low per-meability and high conductivity, respectively. It'1l be of an important role to know the relative permeability curves, reveal their reflectedreservoir characters and master the oil and water distribution and movement of different fluid saturations at the beginning of an oilfield development. References | Related Articles | Metrics

Numerical Simulation of Tectonic Stress Field and Prediction of Fracture Distribution in Qingxi Oilfield YAN Wei-peng*, ZHU Xiao-rmin2 , ZENG Lian-buo2, ZHANG Qun-wei3, ZHANG Zhen-sheng3 , WANG Xiao-shan3 2004, 25 (3):  305-307.  Abstract ( 81 )   PDF (368KB) ( 337 )   Save Qingxi oilfield is a fractured reservoir. The fractures are the main oil-gas reservoir space and controlling factors for petroleum enrichment. To well predict the distribution area and development extent, finite element method (FEM) is applied to make numerical simulation of tectonic stress field for No.1 and No.3 members of Xiagou formation. According to the data of structural evolution, core and well logging，this paper suggests that the effective fractures of Qingxi reservoir were mainly formned in period of Himalayan orogeny. The main types of the fractures are dip-crossing fracture with low angle, interlayer fracture and few high angle fractures. According to the numerical simulation results and Coulomb-Mohr's criterion of fracture, these structural fractures are predicted. The result shows that the fractures are generally developed in this studied area. The major fractured areas are located in eastern and southern Qingxi oilfield. And the high-yielding wells are all situated at the well fractures areas. So these areas are favorable ones for oil-gas exploration and development. References | Related Articles | Metrics

The Measures for Improving W aterflood Efficiency of Useless R eserves in Ya 'erxia Oilfield LI Xiao-jun, YANG Yong, ZHAO Jin-hui 2004, 25 (3):  308-309.  Abstract ( 85 )   PDF (84KB) ( 197 )   Save In this paper, the useless reserves, sand body geometry, sedimentary rhythm and interconnecting feature of Ya'erxia area in Yumen field are investigated, along with detailed discussion of waterflooding characteristics of sand body shaped in diferent settings, by which relevant technological measures for formation fracturing and acid treatment are proposed. It is suggested that the waterflooding effect depends on heterogeneity of the sand bodies for most remained oil distribution in zones with low porosity and low permeability. Hence，in waterflood profile control， the productivity of major sand body should be controlled, considering those low-productivity sand bodies; in selection of properly fracturing horizons, low permeable zones should be fractured primarily in favor of even advancing of injected water. This result can be as a guide for improving development effect and EOR of Ya'erxia oilfield. References | Related Articles | Metrics

New Approach for Determination of Rational and Ultimate Well Spacing Density in Maturing Oilfields LIU Shi-liang, ZHENG Ying-Zhao 2004, 25 (3):  310-311.  Abstract ( 120 )   PDF (366KB) ( 243 )   Save Based on available approaches in analysis and economical evaluation,a new method for calculating reasonable and ultimate well spacing density in an old oilfield of Yumen that has been developed for many years. It takes into account both interest from investment and interests from overhead expenses and crude-selling income year after year. This method can be applied to verify the feasibility of infill drilling in an old oilfield or reservoir, getting rid of taking a risk for uncertain investments. References | Related Articles | Metrics

An Intelligent Model Applied to W ell Logging Interpretation: Development and A pplication LI Guo-he*, WANG Ze-hua2 2004, 25 (3):  312-314.  Abstract ( 78 )   PDF (199KB) ( 167 )   Save This paper presents effective evaluation of well log interpretation by fully utilizing well log data, based on basic principle and method of formation system. That is, using well log data and the results from formation test as a decision-making table of information system，from which the decision making regulation with uncertainty is taken out as its intelligent model in terms of theory of fuzzy set and rough set. Such a model has the characteristics of high non-linearization, high validity and high generalization in use, especially suitable for the evaluation of complex heterogeneous strata as a new tool to well log interpreters. References | Related Articles | Metrics

Application of Rotation Transform and Viterbi Algorithm in Prestack Depth Migration Preprocessing of Wave Equation ZHU Zhen-yu*, LIU Hong*, PEI Jiang-yun2, LV Xiao-lin*, LI You-rming* 2004, 25 (3):  315-319.  Abstract ( 78 )   PDF (536KB) ( 270 )   Save In prestack depth migration with wave equation, the input seismic data grid is required to be regularized grid. However, during the field seismic data acquisition， the visual variation occurs in acquisition system， due to complex landscape or relief and seismic coverage times. Such alias produced by sparse samples along the on-line should be interpolated between tracks. This paper deals with the variance between the seismic line and the coordinate orientation by rotation transform and realizes the auto pickup of events by Viterbi algorithm, obtaining satisfactory results. These two methods are feasible to preprocessing of prestack depth migration of wave equation. References | Related Articles | Metrics

Velocity Analysis of North Fault block in Well Huo-14 and A pplication of Its Forward Model in Jundong Field of Junggar Basin HU Ping*, LIU Ji-shan*, SHI Xin-pu*, CAO Si-yuan2, XU Huai-bao*, WEN Gang-feng3 2004, 25 (3):  320-322.  Abstract ( 77 )   PDF (1349KB) ( 223 )   Save The north fault block in Well Huo-14 is located in deep sag of the Pemian foreland basin of Kalamaili foothill in eastern Junggar basin，in which the main body is under the overthrust nappe of Carboniferous volcanic rocks. The overlying strata of volcanic rocks with high velocity spread in wedge shape being thick in noth and thin in south, so they assume varied complex velocities that affect proper understanding of its inner structures. The forward model technique is applied to prove the existence of the north fault block and the trap shaped by the fault block. In order to describe the inner configuration accurately, a detailed interpretation has been made of its velocity spectnum, setting up average velocity fields for major strata. The abnormal velocity analysis verifies both the interpretation accu-racy and the structural configuration within the fault block. References | Related Articles | Metrics

Application of of Principal Component Prediction in Qingxi Oilfield TANG Guang-hua, ZHAO Qian-ping, WANG Mai-fu, XU Shi-dong 2004, 25 (3):  323-324.  Abstract ( 91 )   PDF (348KB) ( 205 )   Save Principal component analysis and prediction is a technique of detailed well log constraint inversion. Based on well log data and seismic data, it can be applied to provide the wave impedance as similar as well log resolution in accuracy, including lithology and reser-voir rock parameters. Good results are obtained from its application to Qingxi oilfield in sedimentary facies classification， well location demonstration and integrated geological studies. Commercial oil flow has been found in four of six wells drilled in 2002, which contributes to Qingxi oilfield in its productivity construction. References | Related Articles | Metrics

Coalbed Methane Content and Its Distributing Characters in China ZHONG Ling-wen 2004, 25 (3):  325-328.  Abstract ( 203 )   PDF (913KB) ( 206 )   Save According to obtained desorption methane content analysis from domestic coalfield exploration and coalbed gas test wells and development wells in recent years, this paper suggests that the distribution of coalbed methane content are of characteristics of the south-high and north-low, the east-high and west-low in China. The regions with highest methane contents are found mainly in gas-bearing areas or zones in center and south parts of Hunan province and Pingle in South China; those in Yunnan-Guizhou-Sichuan province; those in Qingshui, eastern margin of Erdos basin and Weibei in Shanxi-Shaanxi-Inner Mongolia region; those in south part of Heilongiang-ilin-Liaoning province; secondly， in east part of Hebei-Shandong-Henan-Anhui province. The regions with lower methane contents are in north-cental part of Heilongiang-Jilin-Liaoning province, Beijiang area, east part of Hebei-Shandong-Henan-Anhui province, north part and west central part of Shanxi-Shaanxi-Inner Mongolia region. This result could provide decision-making bases for coalbed gas exploration and development. References | Related Articles | Metrics

Advancing Microbial Enhanced Oil Recovery Technology WANG Hui, LU Yuan, YI Xiang-yi 2004, 25 (3):  329-332.  Abstract ( 107 )   PDF (168KB) ( 482 )   Save Biological technology, especially microbial enhanced oil recovery (MEOR) technology has been paid great attention to in the world. Some pilot tests of MEOR have taken preliminary effects at home and abroad. The typical cases are found in America and Russia. Some field tests are also made in Jilin and Shengli oilfields of China，and have taken inspiring effects of incremental oil production. . Meanwhile, with the development of science and technology, some advanced tools of microbiology such as molecular biology , tracer and vi-sualization technologies etc. have entered into investigating field of MEOR , and become important tools for its mechanism studies. In ad-dition, a series of results have been obtained in relevant theory of hydrocarbon degradation and mathematic model, too. MEOR is being applied from single well treatment toward whole block or field area with distinctive benefits. References | Related Articles | Metrics

A Review on Fault Seal Study ZHAO Mi-fu 2004, 25 (3):  333-336.  Abstract ( 90 )   PDF (209KB) ( 426 )   Save According to the corelation analysis of characterization formulas and applied conditions of clay smear potential, shale smear factor and fault clay ratio， four kinds of origins and limitations of shale smear formulas are pointed out. Various methods and applied conditions of lithology allocation are reviewed. The effects of fault plane and faulted zone on fault seal property are given in the study of lithology llcation. It is suggested that the big challenge for analysis of lithology allocation is to determine the fault scale, total thickness of fault rock and dist ribution of small faults, etc. The fault seal mechanism can be divided into three aspects or 8 types. And the methods for study of fault seal property are classified into fourteen types and discussed. Finally, further research directions or tangets in fault seal are provided from the aspects of fault seal mechanism, studied thinking as well as the application of computer. References | Related Articles | Metrics

Discussion on Genetic A lgorithm Encoding Scale in Geophysical Inversion ZOU Qiang, ZHOU Xi-xiang, ZHONG Ben-shan 2004, 25 (3):  337-339.  Abstract ( 100 )   PDF (310KB) ( 206 )   Save Genetic algorithm (GA) has been widely used in geophysical prospecting. However, the conventional binary coding in GA may occupy huge amount of computer memory and add the load of decoding because of its long code. In a simple geophysical inversion, some other encoding scales show their superiority to binary coding for highly calculating accuracy and faster calculating speed, improving the efficiency of GA. This result provides for a good think ing to further study of application of GA in geophysical inversion. References | Related Articles | Metrics

The Measures for Improving Development Effects of Zhanazhol Condensate Oil-Gas Field in Kazakhstan YANG Rui-qi, GUAN Wei-dong, GUO Shuang gen, Abduresit Turson, DING Yi 2004, 25 (3):  340-343.  Abstract ( 156 )   PDF (617KB) ( 277 )   Save Zhanazhol (Ka Haxon) condensate field, a big oil-gas field in western Kazakhstan, is discovered in 1978 and brought into development in 1983. This paper makes an analysis of the main factors affecting their development from geologic features and development characteristics, and puts forward the measures for improving development efcts，such as enhancing water injection，keeping reasonable formation pressure; perfecting infill well patterns, improving producing reserves extent for maintaining a reasonable oil recovery rate; choosing reasonable thickness of avoiding water-conning and gas-channeling for remedial perforation to improve producing reservoir profile; making timely conversion of recovery process, augmenting producing pressure differential for stable production; . adopting effective measures of production and injection stimulations for keeping higher productivity, and timely development of gas cap for best benefits. The efects of all such proposed measures have been proved by field practices. References | Related Articles | Metrics

The Measures for Improving Development Effects of Zhanazhol Condensate 0il-Gas Field in K azakhstan YANG Rui-qi, GUAN Wei-dong, GUO Shuang-gen, Abduresit Turson, DING Yi 2004, 25 (3):  344-348.  Abstract ( 102 )   PDF (791KB) ( 193 )   Save Zhanazhol (Ka Haxor) condensate field, a big oil-gas field in western Kazakhstan, is discovered in 1978 and brought into development in 1983. This paper makes an analysis of the main factors affecting their development from geologic features and development characteristics, and puts forward the measures for improving development effects, such as enhancing water in-jection, keeping reasonable formation pressure; perfecting infll well pattems, improving producing reserves extent for maintain-ing a reasonable oil recovery rate; choosing reasonable thickness of avoiding water. conning and gas-channeling for remedial per-foration to improve producing reservoir profile; making timely conversion of recovery process, augmenting producing pressure dif-ferential for stable production; adopting effective measures of production and injection stimul ations for keeping higher productiv-ity, and timely development of gas cap for best benefits. The efects of all such proposed measures have been proved by field practices. . References | Related Articles | Metrics