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01 April 2004, Volume 25 Issue 2 Previous Issue    Next Issue

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Plays for Giant Oil Field Prospecting in Junggar Basin HE Deng-fa, ZHANG Yi-jie, WANG Xu-long, JIA Jin-dou, SHI Xin 2004, 25 (2):  117-121.  Abstract ( 93 )   PDF (2089KB) ( 295 )   Save Junggar basin is one with abundant hydrocarbon resources,low degree of exploration and great potentials for oilprospecting. For further petroleum exploration, its wedge-like structure with shallow or thin strata in the north and deep or thickstrata in the south and regional monoclinal structure would be the realistic domains by their determinants for the fact that thesubtle trapping oil-gas reservoirs such as low -amplitude anticline,faulting-lithologic and stratigraphic-lithologic types are primarilydeveloped in middle- and shallow. -buried Jurassic-Cretaceous in the hinterland of Junggar basin; its complex superimposed struc-tural belts shaped by intense thrusting and compresso-shear actions would be the strategic breakthrough domains; while the deep-buried large -scale structures of Carboniferous to Triassic in hinterland of the basin should be the important successive domains. Inaddition, Junggar basin has a characteristic of multiple incremental peaks in oil-gasreserves or OOIP/OGIP. In recent 10 years,much more reserves have been found out from the subtle reservoirs and the middle-deep reservoirs.Hence subtle reservoirs havebecome major targets for further hydrocarbon exploration in Junggar basin. References | Related Articles | Metrics

Complex Petroleum System in Kongquehe Area of Tarim Basin ZHANG Ke-yin, SHAO Zhi-bing, ZOU Yuan-rong 2004, 25 (2):  122-124.  Abstract ( 91 )   PDF (2181KB) ( 457 )   Save The basinal source rocks of Cambro-Lower Ordovician and Jurassic limnetic source rocks occurred in Kongquehe areaof Tarim basin appear in form of multiple oil-gas assemblages and zonal distribution of local structures, with process of multi-stagehydrocarbon accumulations and deconstructions.The existing reservoirs were shaped in period of Late Y anshanian and Himalayanmovements. The complex petroleum system is proved by continuously exploratory results. The study shows that the structural beltsin N-W trend situated in hydrocarbon-generated center of Jurassic and secondary hydrocarbon-generated superimposed area ofCampro-Lower Ordovician possess greater potentials for petroleum exploration. References | Related Articles | Metrics

Reservoir Characteristics of Yan 'an Delta XU Zheng-yu, DONG Yi-long, CUI Jian-jun, LIN Ge 2004, 25 (2):  125-127.  Abstract ( 70 )   PDF (1166KB) ( 148 )   Save This paper highlights the reservoir sand body, petrology, pore structure, petrophysical properties and their effects in Yanan delta by way of macroscopic and microscopic study, including thin-section and cast thin-section analysis data, etc. Inte-grating with petroleum exploratory progress of the delta, this paper proposes statistically that Chang-4+5, Chang-6' and Chang-6?oil layers in target area are better than other layers. In general, the microfacies-developed zone of distributary channel in thedelta front is the most favorable for hydrocarbon prospecting.In spite of belonging to low porosity and low permeability reservoirwith compaction and dominated by intergranular dissolved pores and intergranular residual porosity, Yan'an delta still has greaterpotentials for petroleum development compared with the similar domestic fields. References | Related Articles | Metrics

Restoration of Eocene Erosion Thickness in Gaoyou Sag LIU Xiao-ping, YANG Li-gan, XU Jian 2004, 25 (2):  128-130.  Abstract ( 86 )   PDF (1410KB) ( 226 )   Save The tectonic subsidence of Subei basin ceased during Sanduo movement from Late Eocene to Oligocene. It had broughtabout the end of faulting growth in it and depositional break for 18Ma, with strong uplifting,erosion and absence of UpperEocene and Oligocene. The imbalanced erosion of Gaoyou sag is analyzed by the data of homogeneous temperature, clay mineral,vitrinite reflectance and C29-20S/(20S+20R) sterane ratio. It is shown that the erosion becomes stronger gradually from deep sagzone to slope zone,fault terrace zone and low uplift. The erosion thickness is estimated by the method of interval transit timeand forward numerical simulation of vitrinite reflectance. The results of them coincide with each other. The total erosion thicknessis about 400~1 600 m, where deep sag zone is of 400~600 m, slope zone of 500~1 200 m, fault terrace zone and low uplift of1 000~1 600 m in total. Such estimated values are bigger than previous results of qualitative estimation, which mean that renewalstudies should be made in the burial history, geothermal history, hydrocarbon accumulation history and oil-gas reservoir distributionn Gaoyou sag. References | Related Articles | Metrics

The Differential Hydrocarbon Accumulation in Long-Axis Anticline of Honggang Field,Songliao Basin CHEN Guo-li 2004, 25 (2):  131-133.  Abstract ( 84 )   PDF (627KB) ( 426 )   Save The regular distribution of oil, gas and water due to gravitational differentiation tends to the fact that a gas reservoirforms in structural trap at higher part, while an oil reservoir in structural trap at lower part. However, there exist gas reservoir intrap at lower part and oil reservoir in trap at higher part due to differential hydrocarbon accumulation. Many typical cases haveindicated this abroad.In long-axis anticline of Honggang field in Songliao basin, it is indicated from formation tests that Hong-l31 trap belongs to a gas reservoir which lies in lower sub-layer G13 of Gaotaizi sand layer-II, Hong-7 trap is an oil-gas reser-voir at higher part, and in Hong-l6 trap merely contains water which lies at the top. Based on detailed analyses of the structuraland reservoir characteristics, it is shown that the basic conditions for differential hydrocarbon accumulation could appear in layerGl3 and can be used for well interpreting its oil-gas distribution. So the sub-layer G13 is found to be as a first and typical caseof the differential hydrocarbon accumulation in China. References | Related Articles | Metrics

Evaluation on Vertical Sealing Nature of Main Faults in Chegu-20 Burried Hill FU Guang, FU Xiao-fei, MENG Qing-fen 2004, 25 (2):  134-136.  Abstract ( 77 )   PDF (876KB) ( 210 )   Save The faults development and evolution features in Chegu-20 burried hill as well as their vertical sealing mechanisms andaffected factors are analyzed. The main factors controlling vertical sealing faults are the pressure exerted on fault plane and theshale content. From the modeling result of compressive experiment,the plastically deformed limitation of mudstone is presented,and the method for prediction of sandy and shale contents in fault zone is established by its lithology and fault throw.Based onthese, the vertical sealing nature of Chegu-20 burried hill in Carboniferous-Permian to Paleogene are evaluated. It is pointed outthat the faults are all characterized by vertical sealing nature in C-P to Es* except for faults F3, F42 and F? in Line-298 and a-long Chegu-203-Chegu-20-Chegu-201. They show that this area possesses significant conditions for hydrocarbon accumulation andpreservation. References | Related Articles | Metrics

The Hydrocarbon Accumulation Model of Middle Segment in Dongbu (Eastern) Sag of Liaohe Basin JIANG Jian-qun, ZHANG Zhan-wen, ZHANG Fu-gong, LI Ming-kui 2004, 25 (2):  137-140.  Abstract ( 75 )   PDF (1349KB) ( 483 )   Save The complex faulting system and abnormally active volcanic process make the middle segment of Dongbu sag in Liaohebasin possess unique hydrocarbon accumulation model.Establishment of such a model is based on relationship between the vol-canic process and hydrocarbons in it and the analysis of reservoir rocks and spatial distribution.Study shows that Sha-3 layer of Oulituoz area is rich in petroleum due to premiere assemblages among enough oil sources, fair transport system and fine energyconfiguration. The petroleum accumulation model is characterized by vertical migration assisted with lateral short-distance migration.But in Tiejianglu area, petroleum migration and accumulation are different from those in Oilituoz area,its channel media forpetroleum migration are dominated by interconnected sands with little vertical migration along the faults,thus resulting in petroleum distribution primarily in the middle-lower section of Sha-3 layer. References | Related Articles | Metrics

Analysis of Structural Model of Gumudi Anticline in Southern Margin of Junggar Basin LI Xue-yi, LIU Lou-junl, CHEN Wei 2004, 25 (2):  141-142.  Abstract ( 95 )   PDF (819KB) ( 278 )   Save The southern margin of Junggar basin underwent Tianshan movement in late Himalayan orogeny and formed a series ofanticlines and related faults. Owing to its complex surface and subsurface geologic conditions, the seismic reflection data from thisarea are poor and the structural style varies and is always troublesome in discrimination.In order to establish the properstructural style, this paper takes the structural description of Gumudi anticline as an example, the fault-folded theory as a guide,and the structural modeling technique as a tool for anatomizing complex structures, finally, develops a model of structural geologyfitting for real situation of this area. The procedure for modeling is also presented herein. References | Related Articles | Metrics

Hydrocarbon Conduit Systems and Migration-Accumulation Model in Tahe Oilfield CHEN Qiang-lu, HUANG Ji-wen 2004, 25 (2):  143-146.  Abstract ( 94 )   PDF (1329KB) ( 248 )   Save Tahe oilfield in Tarim basin is characterized by multi-stage hydrocarbon generation, multi-channelmigration and multi-stage petroleum accumulation.This paper discusses the hydrocarbon conduit systems such as fault and structural fissure,unconformity and paleo-weathering crust, Ordovician vug and fracture as well as interconnected sand body in light of Tahe oilfieldand its regional geological situations.The study shows that it is these systems that control the hydrocarbon migration andaccumulation in different periods and reservoirs,the formation and evolution of different areas and types of pools. The systemscan be classified with network-like model and zigzag-like model for petroleum migration and accumulation. References | Related Articles | Metrics

The Tectonic Evolution in Hetian Paleohigh and Its Petroleum Distribution SUN Wei, LIU Shu-gen, XU Guo-qiang, LI Guo-rong 2004, 25 (2):  147-149.  Abstract ( 133 )   PDF (760KB) ( 459 )   Save The paleohigh is the center of long-term hydrocarbon migration and accumulation, and also one of the major domainsfor further exploration of west-central China. Hetian paleohigh in Tarim basin is a paleohigh with deposition and denudation.Itsformation and evolution which have greatly affected the hydrocarbon generation,migration,accumulation and preservation in thestudied area can be divided into three stages: 1) uplifted and denudated stage in Caledonian movement,2) buried stage inHercynian movement, and 3) destructed stage in Himalayan movement. And it became a slope at last following these processes. Itwas the existence of Hetian paleohigh that hydrocarbon generation, adjustment, migration and trap formation in it were in optimalmatched conditions. The evolution of it has a profound geological significance for the source rock development and hydrocarbonaccumulation in this area. References | Related Articles | Metrics

Improved Genetic Algorithm for Wave Impedance Inversion LI Jing, CHEN Yu-ming, WANG Zhen-guo 2004, 25 (2):  150-152.  Abstract ( 76 )   PDF (1554KB) ( 259 )   Save Improved genetic algorithm takes improving on traditional genetic algorithm for practical question of seismic wave impedance inversion, based on the best choice and evolutional principle in natural biology genetic process. This algorithm takesquinary system coding instead of binary system coding before introducing Boltzmann exist mechanism in genetic operation,and can be used for inversion of seismic wave impedance so that allows object function to meet an order as required and allows nonlinear method of annealing genetic algorithm to be applied in the inversion of seismic wave impedance. References | Related Articles | Metrics

Application of Seismic Attributes in Prediction of Dolomite in Biyang Sag JIN Ling, DING Yan-hong, SU Gui-zhi, ZHANG Yu-xia 2004, 25 (2):  153-155.  Abstract ( 82 )   PDF (1041KB) ( 207 )   Save (Research Institute of Exploration and Development, Henan Oilfield Company, Sinopec, Nanyang, Henan 473132, China) References | Related Articles | Metrics

Difficulties and M easures for Development of Low Permeability Tight Gas Reservoirs and Condensate Gas Reservoirs LI Shi-lun, SUN lei, DU Jian-fen, TANG yong, ZHOU Shou-xin, GUO ping, LIU Jian-yi 2004, 25 (2):  156-159.  Abstract ( 160 )   PDF (317KB) ( 769 )   Save Low permeability tight gas reservoirs and condensate gas reservoirs account for a rather high proportion of domestic gas re-serves, but many of them have low productivity. So it is significant to develop these reservoirs efficiently for continuous and stabledevelopment of China's petroleum industry. Around the problems of the development of deep low permeability tight gas reservoirs andcondensate gas reservoirs,this paper makes an analysis on the geologic and development characteristics of these reservoirs and pre-sents ten proper technologies.Finally,five technical measures for the development of such gas reservoirs are proposed in detail.These are deep fracturing technology, treatment technology of accumulated liquids in condensate gas well and near well bore, gas in-jection technology when the formation pressure is lower than the maximum condensatepressure, phase behavior analysis technologyn porous media of low permeability tight condensate gas reservoir and other gas reservoir engineering technologies. References | Related Articles | Metrics

A Decomposition Method of Skin Factor for Gas Well CHEN Yuan-qian 2004, 25 (2):  160-164.  Abstract ( 105 )   PDF (1018KB) ( 399 )   Save Skin factor of near wellbore zone is an important parameter to evaluate productivity and completion efficiency of oiland gas wells. However, the skin factor determined by pressure buildup curve of gas well is a total skin factor which includespenetration degree skin factor, perforation density skin factor, high velocity turbulence skin factor and mud damaged skin factor.Based on concerned references [1-6], a decomposition method of the skin factor of gas well is proposed in this paper. Theeffectivity of the method is indicated by case applications. References | Related Articles | Metrics

A Mathematic Model for Non-Darcy Flow at High Flow Rate ZHANG Lie-hui, ZHU Shui-qiao, WANG Kun, ZHOU Lin 2004, 25 (2):  165-167.  Abstract ( 200 )   PDF (704KB) ( 305 )   Save Forchheimer's Equation,a classical equation put forward by Forchheimer in 1901,has been used for offset the deficiency of Darcy's law at high flow rate by way of adding a non-Darcy term into Darcy's law.This term is a product among the non-Darcy coefficient, the fluid density and the square of flow velocity. To estimate the non-Darcy coefficient as accurately aspossible is one of the most important aspect for determination of non-Darcy effects. This paper establishes a new fully implicit 3-D gas reservoir mathematic model with multiple types of reservoirs and scopes of permeability based on study of a great numberof literatures and analysis of mathematic descriptions of various non-Darcy effects.In this model, the non-Darcy effect of gas athigh flow rate can be more effectively concerned about. In addition, using OrthoMin method to solve the algebraic equation seriesis quick in speed and reliable in stability. References | Related Articles | Metrics

Creation of Component Adsorption Isothermal Curve for Porous Media of Gas Reservoir MEI Hai-yan, ZHANG Mao-lin, DU Zhi-min, LI Min, SUN Liang-tian 2004, 25 (2):  168-171.  Abstract ( 96 )   PDF (1388KB) ( 174 )   Save For the different adsorbates in the same adsorbent (porous media), the adsorption powers measured under the differenttemperatures are correlated with the adsorption potentials. The relative regression equations are given by matching the experimentaladsorption data from adsorption potential theory and definition of Dubinin adsorption potential. The regression equation can be usedto determine the average petrophysical parameters for a gas reservoir (Case 2)and create the adsorption isothermal curves forvarious components under given gas-layer temperature in it. It provides significant basic data and research methods such asadsorption phase equilibrium simulation and oil-gas reservoir numerical simulation for study of adsorption processes in porous media. References | Related Articles | Metrics

A dsorption Equilibrium Model and Its Verification of Gas Mixture ZHANG Mao-lin, MEI Hai-yan, DU Zhi-min, LI Min, SUN Liang-tian 2004, 25 (2):  172-176.  Abstract ( 78 )   PDF (1697KB) ( 299 )   Save Gas mixture adsorption is related to temperature and pressure, also there exists the competing adsorption phenomenawith the change of gas composition.The gas mixture adsorption model can be used to calculate the adsorption equilibriumquantity of each component of the gas mixture at certain temperature and pressure by using pure component or bi-component gasadsorption isotherm. The two-phase equilibrium calculation model with the adsorption phase and freedom gas phase is developed .using Flory Hugging Vacancy Solution Model(FHVSM)of gas adsorption.For two samples of dual gas mixture adsorptionequilibrium, the adsorption equilibrium simulation calculation is completed after regressing the parameters of the pure componentadsorption isotherm. The studied result shows that FHVSM can be used to describe the gas mixture adsorption equilibrium andsimulation calculations of adsorption equilibrium for both hydrocarbon gas mixture and non-hydrocarbon gas mixture. References | Related Articles | Metrics

Buildup Test Analysis of Condensate Gas Well Considering Adsorption Effect HUANG Quan-hua, LI Shi-lun, SUN Lei, XU Shi-guo 2004, 25 (2):  177-179.  Abstract ( 91 )   PDF (812KB) ( 197 )   Save n regard to present well test interpretation for gas condensate well, single phase pseudo-pressure method for dry gaswell is still be used in general, of which the effect of porous media on adsorption of condensate oil and gas is not considered.But more and more experiments and theoretical studies indicate that porous media adsorption is of greater influences on thepercolation of condensate oil and gas.This paper proposes the method for buildup test analysis of condensate gas wellconsidering adsorption effect based on differential equation of percolation with adsorption effect of condensate gas well and draw-down test analysis.Case study shows that the effect of porous media adsorption could result in decreasing effective permeability,increasing skin factor,reducing detection radius of gas well in well test interpretation. For a condensate gas reservoir with highheavy hydrocarbon content and low porosity, the influence of porous media adsorption would be much more apparent. Hence, theinfluence of porous media interfacial phenomena on the percolation and well test in a condensate gas well can not be neglected. References | Related Articles | Metrics

Study on Numerical Simulation of Hutubihe R eservoir in Luliang Oilfield ZHANG Ji, ZHANG Lie-hui, ZHANG Hong-mei, JIANG Xiao-hu, ZHANG Ju-zeng 2004, 25 (2):  180-181.  Abstract ( 96 )   PDF (461KB) ( 203 )   Save Hutubihe reservoir(K]h26~Kph2) of Wellblock Lu-9 in Luliang oilfield of Junggar basin is an edge-water reservoircharacterized by low amplitude structure, complicated oil-water relationship and intensive heterogeneity. Applying numerical simulationmethod,integrated with results of detailed reservoir description and reservoir engineering study,this paper presents technicallimitations of rational development of Hutubihe reservoir and determines that waterflooding process and inverse 9-spot pattern shouldbe adopted with the cut-offs such as rational production rate of 2.9%, reasonable injection-withdrawal ratio of 0.8, sound pressurelevel of 9.0MPa. It is indicated that these numerical simulation results are helpful to Luliang oilfield for high effective development. References | Related Articles | Metrics

Feasibility Study of CO, Injection for Heavy Oil Reservoir after Cyclic Steam Stimulation LUO Rui-lan, CHENG Lin-song 2004, 25 (2):  182-184.  Abstract ( 110 )   PDF (1082KB) ( 230 )   Save In accordance with the fact that many domestic heavy oil reservoirs or blocks have entered into their late stage ofcyclic steam stimulation and hence the development effects are getting worse, feasibility of CO2 injection for different viscosities ofheavy oil reservoirs following steam stimulation is studied using methods of numerical simulation and reservoir engineering andtaking Lengjiabao heavy oil field in Liaohe etc. as samples. And the results from the simulation and field pilot test are evaluatedeconomically. Study shows that for common heavy oil after cyclic steam stimulation, the higher the oil viscosity, the greater theutilization factor of CO, injection, and the more feasible by CO, stimulation process; for extra and super heavy oil, one to threesteam stimulations at least are performed as necessaryfollowed by converting it into CO, stimulation process so that good benefitcould be gained. These results are of significance for field operation and production of heavy oils. References | Related Articles | Metrics

An Optimized Model for Oil Development Programming/ Decision Support System JIANG Hou-shun, LIU Ce, YE Yi-ping 2004, 25 (2):  185-187.  Abstract ( 81 )   PDF (530KB) ( 212 )   Save The oil development programming/ decision support system (ODPDSS) is a systematic engineering featured by extensiveknowledge and complicated contents in design.And reasonable usage and distribution of resources is the key of its run ofdecision-making.This paper proposes the single-object linear programming model which is a distribution method for resourceoptimization based on certain production rate and low cost and the multi-object linear programming model which is a distributionone for highest production rate and lowest cost.These two models can be used for dealing with fully exerting potentials of anoilfield under the factor control of decision-making and for the purpose of achieving optimal production of it. References | Related Articles | Metrics

Suitability Study of Nitrogen-Foam Flood in Heavy Oil Reservoir An example of L iaohe oilfield YANG Guang-lu, LIN Yu-qiu, LIU Jia-lin, BAO Jun-gang 2004, 25 (2):  188-190.  Abstract ( 88 )   PDF (1065KB) ( 255 )   Save Up to now, most of heavy oil reservoirs in Liaohe oilfield have undergone steam stimulation development, some of themwith lower crude viscosity have undergone processes from transitory conventional recovery into waterflooding. However, most of theheavy oil reservoirs follow ing steam stimulation recovery appear in obvious inconsistency in vertical and horizontal producingperformance due to their serious heterogeneities.Moreover,with precipitous pressure decline and degassed crude viscositydecrease, the development effectiveness has been distinctly getting poorer. Therefore, converting available development process ofthis type of reservoirs is the most urgent situation. This paper presents the studies of the mechanism of nitrogen-foam flood forEOR,and suggests that the mechanism of nitrogen-foam flood used to regulating injection profile is proper to improve thedevelopment effectiveness of these reservoirs.In view of few tests of large-scale nitrogen-foam flood at home and abroad,suitability research of such a flood is systematically performed using numerical and physical simulation approaches.Finally, sixheavy oil blocks in Liaohe oilfield are selected to be as field operation ones based on the reservoir conditions suitable fornitrogen-foam flood given in this paper. References | Related Articles | Metrics

Usher Model for Water Cut Prediction in W aterflood Field ZHANG Ju-zeng, ZHANG Lie-hui, ZHANG Hong-mei, PENG Yong-can 2004, 25 (2):  191-192.  Abstract ( 123 )   PDF (409KB) ( 386 )   Save It is significant for predicting watercut vs time in a waterflood field. Usher model, a model for general prediction ofpetroleum economy and resources, is used to predict watercut based on the increasing watercut in waterfood field.By analysis,this paper points out that available Logistic model and Gompertz model are the specific ones of Usher model.And field application indicates the practicality and validity of Usher model. References | Related Articles | Metrics

Estimation of Economic Recoverable Index for High Watercut Stage in Karamay Conglomerate Reservoir CHEN Yu-chuan, SHI Jun, WANG Xiang-dong, DONG Guang-hua, CHEN Xu-hua 2004, 25 (2):  193-195.  Abstract ( 86 )   PDF (774KB) ( 215 )   Save This paper presents three methods for estimation of economic recoverable reserve, surplus economic recoverable reserveand economic recovery factor, i.e. watercut vs cumulative oil production curve, waterflood type curve and monthly oil productionvs time curve, which are based on the characteristics of Karamay high watercut conglomerate reservoir and domestic policy ofpresent finance and taxation.The typical case estimation shows that these methods are effective and feasible for obtaining aboveindices. References | Related Articles | Metrics

Realization of Integrated Technology of Reservoir Description with Numerical Simulation ZHANG Huiyong WU Xiaojun Abduresiti Turson, XU Changfu WU Xuquan, QIN Jun, KONG Chuixian 2004, 25 (2):  196-198.  Abstract ( 77 )   PDF (687KB) ( 238 )   Save Taking Wutonggou reservoir in Shanan oilfield as an example,1 method for realization of integrated technology ofreservoir description with numerical simulation is expounded. .Firstly, the 3-D geologic model is developed by using reservoirdescription technology, based on integrated analysis of the mode uncertainties,selecting a suitable geologic model for actualreservoir as input data of numerical simulation. Secondly, the reservoir numerical simulation model is developed by using griddingtechnology integrated with production performance.Finally, the reasonable technical limit for reservoir recovery is proposed byindex prediction and effectiveness evaluation based on the history match and different recoveryprocesses affecting reservoirdevelopment efficiency.Applying the integrated technology of reservoir description with numerical simulation can improve theaccuracy and quality of geologic model during numerical simulation, and provide reliable technical guarantees for the optimizationof development process and the in-depth study of remained oil distribution. References | Related Articles | Metrics

Determination of Perforation Intervals of Wells in Bottom-Water Reservoirs with Barriers LI Chuan-liang 2004, 25 (2):  199-201.  Abstract ( 97 )   PDF (1758KB) ( 333 )   Save Determination of perforation intervals and optimal shot density of wells in bottom-water reservoirs with barriers isstudied and presented. The study shows that barriers with both high critical rates and high production rates existed in bottom-water reservoirs are generally protected or retained, while those with high critical rates and low production rates or low criticalrates and high production rates should be perforated.The wells perforated by distribution of the barriers appear in higherproduction rates and postpone the breakthrough time of bottom-water on a large scale. Bottom-water reservoirs with barriers displayabundant natural drive energy in development and overcome the drawbacks of short water-free oil production period in bottom-water reservoirs without barriers. References | Related Articles | Metrics

Determination of Displacement Efficiency and V olumetric Sweep Efficiency XIANG Tian-zhang, LI Lu-bin 2004, 25 (2):  202-203.  Abstract ( 136 )   PDF (420KB) ( 256 )   Save In accordance with one dimensional waterflood theory of Buckley-Leverett,mathematical relationship between oildisplacement efficiency and recovery percent of recoverable reserves as well as minimum value of displacement efficiency arederived. And the numerical model of this relationship from a case of Liaohe field is developed accordingly. In addition, using therelationship among recovery percent,displacement and volumetric sweep efficiency, the equations for estimation of the volumetricsweep efficiency and the recovery percent of recoverable reserves are obtained, based on which the volumetric sweep efficiencyand the potential analysis of displacement efficiency in late stage of waterflooding along with development regime to be adoptedare proposed. The actual application is identical to the calculated results. References | Related Articles | Metrics

Model Database of Low-Velocity Layer in Surface of Tabei Area, Tarim Basin GU Jun-lun, LI Hong, CAO Li 2004, 25 (2):  204-205.  Abstract ( 103 )   PDF (340KB) ( 168 )   Save In 2-D seismic data processing, to control the discrepancy in closing of static correction parameters tends to improvethe discrepancy in closing of seismic profile.Through establishing a database of surface low-velocity layer of Tabei area in Tarimbasin, coordinating data from 2-D and 3-D low-velocity layer, searching and eliminating singular values, and then inputting them .into the database, this paper develops a model of surface low-velocity layer that can be used steadily and repeatedly, by whichobtains the gridding low-velocity layer data generated after smoothing and interpolation using uniform calculation method.Usingsuch a model database can not only shorten the data processing cycle, but also improve the discrepancy in closing of seismicprofile fleetly and reliably. References | Related Articles | Metrics

The Study and Practice of Condensate Gas Reservoir Converted into Underground Gas Storage YANG Shu-he, TIAN Jin-hai, LI Bao-rong, YANG Bo, ZHU Xiao-li 2004, 25 (2):  206-208.  Abstract ( 91 )   PDF (1313KB) ( 346 )   Save The underground gas storage plays an important role in adjusting contradiction of supply and demand of natural gas inwinter and summer, ensuring the requirement of consumers and optimizing the function of gathering and transferring system.Theconstruction of such an underground gas storage abroad has hundred of years history,but it is just in initial phase in China.Along with the implementations of north Shaanxi's natural gas transferred toward Beijing and the Blue Sky project in Beijing, theguarantee of the use of natural gas of Beijing has become the premier issue of natural gas supplier. On the basis of explanationof concept and theory of undergroun gas storage, the chief conditions as necessary for construction of the underground gas storageare provided. Through the analysis of investigation results of concerned stuffs or data at home and abroad, the geology-selectedrules for construction of underground gas storage have been summed up. At the same time, taking the construction project ofunderground gas storage of the condensate gas reservoir in Dagang oilfield as example, the design gist, theory and running projectoptimization are presented. References | Related Articles | Metrics

On Gas Accumulation and Preservation FU Xiao-yue 2004, 25 (2):  212-214.  Abstract ( 140 )   PDF (252KB) ( 259 )   Save Natural gas accumulation is a process of dynamic balance between gas accumulation and gas fugitive emission, in which the inflow and preservation of gas are the key factors for gas reservoir.The preservation of gas-bearing basin primarily depends on its cap rock, late tectonic movement, forming time of gas reservoir, gas supply area and intensity. Normally, a largegas field has its hydrocarbon-generating intensity of over 20x108 m3/km2. The study shows that from the whole to the local, usingmultiple methods and parameters for systematic analysis is a foundation of proper hold and understanding of petroleum prospectsin an area. This paper stresses the effect of pressure seal on gas accumulation and preservation. The pressure system can be asan important index for discrimination of whether a gas-bearing basin possesses sealing and preservation conditions on the whole ornot. References | Related Articles | Metrics

Aryl-Isoprenoids in Crude Oil and Its Implication in Geological Exploration Aryl-Isoprenoids in Crude Oil and Its Implication in Geological Exploration 2004, 25 (2):  215-218.  Abstract ( 96 )   PDF (1920KB) ( 413 )   Save Investigations of aryl-isoprenoids in sedimentary organic matter suggest that these compounds are the diagenetic productsof certain precursors from photosynthetic green sulphur bacteria Chlorobiaceae,indicating that its source rock was formed in anintense reductive environment.Marine oils from the tableland-basin region in Tarim basin generally contain abundant aryl-isoprenoids with the carbon number range of C]o~C23 The pyrolytic products of the bitumen fraction in the oils are also characterized by a typical sulphur bacteria origin,i.e.,an abnormal enrichment of tetra-methyl benezenes in the C2~C5 alkylbenzene fraction. These data indicate that the major marine oil and gas were originated at least from one set of the importantsource rocks developed in a water-layered anaerobic sedimentary environment in the tableland-basin region of Tarim basin,iraddition to the consensus that they were derived from the Upper-Mid Ordovician sedimentary rocks with clay -mottar dome faciescontrolled by the upwelling ocean current in an incline at the platform margin. References | Related Articles | Metrics

Some Disputable Issues about Petroleum Geology И.М.Шахновский 2004, 25 (2):  219-224.  Abstract ( 81 )   PDF (547KB) ( 312 )   Save According to petroleum organic origin theory, the original materials for hydrocarbon generation are the dispersed organicmatters in rocks. But a great amount of actual data indicate that the dispersed organic matters in rocks are not entered into theprocess of hydrocarbon generation, and conditions required for extracting organic matters from powder rock samples in a lab arenot existed in nature. In contrary, there exist inexhaustible free hydrogen and volatile carbonide in deep crust, which may reacteach other under high temperature and high pressure in mantle source,forming hydrocarbon accumulations provided withhydrocarbon fluid such as oil field,gas field,bitumen deposit and combustible shale. They could all be generated by deepinorganic fluid in Neogene.n addition, this paper presents an idea of coal can be formed by deep hydrothermal fluid as thesame as crude oil.During the process of petroleum generation and accumulation caused from mantle hydrothermal fluid,discordogenic fault or transport faulting broken to the mantle would play the most significant part. Related Articles | Metrics

Difficulties andM easuresfor Development ofLow Permeability TightGas R eservoirs and Condensate Gas. R eservoirs LI Shi-lun, SUN lei, DU Jian-fen, TANG yong, ZHOU Shou-xin, GUO ping, LIU Jian-yi 2004, 25 (2):  225-230.  Abstract ( 68 )   PDF (381KB) ( 174 )   Save Low permeability tight gas reservoirs and condensate gas reservoirs account for a rather high proportion odomestic gas reserves, but many of them have low productivity. So it is significant to develop these reservoirs effi-ciently for continuous and stable development of China's petroleum industry. Around the problems of the developmentof deep low permeability tight gas reservoirs and condensate gas reservoirs, this paper makes an analysis on the geo-logic and development characteristics of these reservoirs and presents ten proper technologies. Finally, five technicalmeasures for the development of such gas reservoirs are proposed in detail. These are deep fracturing technology,treatment technology of accumulated liquids in condensate gas well and near well bore, gas injection technology whenthe formation pressure is lower than the maximum condensatepressure, phase behavior analysis technology in porousmedia of low permeability tight condensate gas reservoir and other gas reservoir engineering technologies. References | Related Articles | Metrics