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01 August 1998, Volume 19 Issue 4 Previous Issue    Next Issue

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NEW VIEWPOINT OF FORMING LAOJUNMIAO OILFIELD An Zuoxiang 1998, 19 (4):  265-269.  Abstract ( 155 )   PDF (262KB) ( 302 )   Save It has always been considered that the oil in Laojunmiao oilfield was sourced from Qingxi sag by means of secondary migration, and this viewpoint has been verified by obvious lateral change of crude oil properties.However, analysing the forming time of Laojunmiao anticline combined with hydrocarbon generation and expulsion from Lower Cretaceous source rock in Qingxi sag, we discovered that the formation of Laojunmiao oilfield has a close relation with other oilfields in anticlinal belt, which is the result of secondary oil generation and remigration.Based on this viewpoint, it can be inferred there is better hydrocarbon potential in northwestern margin of Qingxi sag, new discovery is expected in oil/gas exploration over basins in the whole Altun strike-slip structural belt. References | Related Articles | Metrics

THE ROLE OF FAULT IN OIL/GAS MIGRATION AND ACCUMULATION IN BIYANG SAG Zhang Xinshe, Zhang Shulin, He Zurong, Wang Zhengwen, Wu Qingyao 1998, 19 (4):  272-274.  Abstract ( 88 )   PDF (201KB) ( 215 )   Save Practical production data showed that there are eight types of fault sealing forms and three kinds of sealing mechanisms i.e.fault surface sealing, opposite side rock layer sealing and pressure sealing of pore fluid.The effect of fault activity on oil/gas accumulation existed in two sides :① syngenetic normal fault in active stage acted as flow passageway, ② junction mode of opposite sides changed.Based on study of faults in several major oilfields in the sag, it is showed that sealing capacity and characteristics are related with fault size, junction mode of opposite sides occurrence, burial depth, fluid property and fault activety etc.. References | Related Articles | Metrics

SIMULATION EXPERIMENT WITH COALIFICATION OF LIGNITE Huo Qiuli, Du Hongwen, Zhou Ping 1998, 19 (4):  275-277.  Abstract ( 94 )   PDF (154KB) ( 191 )   Save Simulation experiment with coalification of lignite in Shulan coal mine, Jilin province was made to examine the component characteristics of product at different temperature stage, carbon isotope characteristics of methane in gaseous products, and coal-formed oil and its expulsion during coalification.It is suggested the temperature is the key control on change in products.The following conclusions can be reached :① nonhydrocarbon, saturated hydrocarbon and olefinic hydrocarbon are main gaseous products from coalification.Nonhydrocarbon is dominant in low-temperature stage, the content of methane increase with temperature, and heavier hydrocarbon gas peaks at 400 ~ 450 ℃.② carbon isotope of methane in gaseous products from coalification becomes heavier with temperature.③coal can generate and expel oil.It has expelled oil before 350 ℃, and peaks at 375~ 425℃. References | Related Articles | Metrics

HYDROCARBON GENERATION MODEL OF SOURCE ROCK IN JUNGGAR BASIN Ma Zhe, Ning Shuhong, Jiang Li 1998, 19 (4):  278-280.  Abstract ( 75 )   PDF (160KB) ( 257 )   Save Hydrocarbon generation models of each major source bed in Junggar basin were established with hydropyrolysis method, and hydrocarbon generation models of kerogen in Mahu and Jimsar sags with dynamics parameters. Oil generation of source rock in Junggar basin peaks at Ro =1.0%~ 1.2 %.At Ro >1.0%, gas is generated in a large amount. The source rock in Permian has strong oil and gas potential, and other source rocks have strong gas potential but weak oil potential, the oil generation threshold of source rock in Fengcheng formation(Upper Permian)in Mahu sag is at the depth of 3 700m, and the oil generation threshold of source rock in Lucaogou formation(Upper Permian)in Jimsar sag at the depth of 3 250 m. References | Related Articles | Metrics

STUDY ON CLUSTER ANALYSIS OF APPROACH DEGREE OF FUZZY MATTER-ELEMENT Xiao Fangchun 1998, 19 (4):  281-283.  Abstract ( 81 )   PDF (139KB) ( 192 )   Save Based on the fuzzy matter-element analysis and approach degree concept, cluster analysis method of approach degree of fuzzy matter-element was presented to have established evaluation and classification standard of reservoirrs.The result of the case study agrees well with that of other methods and corresponded to the practice.This method may be referred. References | Related Articles | Metrics

CHARACTERISTICS OF PORE STRUCTURE OF RESERVOIR IN XINKAI AREA, LIAOHE OILFIELD Zhong Dakang 1998, 19 (4):  284-286.  Abstract ( 81 )   PDF (188KB) ( 187 )   Save Based on the studies of pore cast thin section, electric microscope scanning, image analysis and mercury injection test of 32 sandstone samples with different petrophysical properties from five oil sand layers in seven wells in Xinkai area of Liaohe oilfield, this paper calculated seven parameters of pore characterization, thirteen throat characterization, three pore-throat connection and one characterizing complexity of pore structure.In all, the reservoirs in this area have large pore, wide throat, better sorting and pore-throat connectivity.Capillary pressure curves mostly have low and wide and gentle platform segment.There are some differences in different oil sand layers, Ⅰ and Ⅱ oil formations in Sha 1 member have the best pore structure, next is Ⅲ and Ⅳ oil formations, and Ⅳ oil formation in Sha 3 member is the worst. References | Related Articles | Metrics

FRACTAL CHARACTERISTICS OF FAULT AND FRACTURE IN ORDOVICIAN RESERVOIR IN LUNNAN AREA Gu Qiaoyuan, Han Jianfa, Zhang Yaotang 1998, 19 (4):  287-289.  Abstract ( 74 )   PDF (168KB) ( 226 )   Save By applying fractal theory to study Ordovician fault and reservoir fracture in Lunnan area in northern Tarim basin, it is shown that the distribution of fault and reservoir fracture in study area is of fractal structure and strong autocorrelation (correlation coefficient more than 0.99).Further study showed that the fault distribution trend in plane corresponds to fracture developed belt of reservoir.Reservoir is the key to explore oil in carbonate rock.In order to clarify hydrocarbon potential of Ordovician in Lunnan area, we should start to operate in the district with best-reservoir quality. Fractal study showed that the west platform has the best-reservoir quality in Lunnan area, and therefore is the first block of oil and gas exploration. References | Related Articles | Metrics

SPOROPOLLEN ASSEMBLAGE OF SANJIANFANG FORMATION IN MIDDLE JURASSIC IN TAIBEI SAG, TURPAN-HAMI BASIN Ji Liming, Wang Fatai, Zhang Xiaobao, Wang Wuhe 1998, 19 (4):  290-298.  Abstract ( 75 )   PDF (329KB) ( 209 )   Save Tabei sag is the main hydrocarbon-bearing area in Turpan-Hami basin, while the thick stratified sandstone of Sanjianfang formation is the main reservoi r in this area.Based on the analysis of samples from Wells Pu 1 and Caonan 1, sporopollens fossils discovered in Sanjianfang formation consist of 33 genera 69 species, the sporopollen assemblage can be established as Cyathidi tes-Classopollis-Picei tes according to the percentage of genera and species and their geologic significances.It is dominated by gymnospermous pollen, accounting for 60 %, next is the pteridophyta spore, accounting for 39.6%.By analysing the geologic history of main classes and important genera and species, along with the contact relationships of the Sanjianfang formation wi th overlying and underlying strata, i t is considered that the sporopollen assemblage from Sanjianfang formation is similar to the one from Lanqi formation in western Liaoning province.Its geologic age is the middle stage of Middle Jurassic, corresponding to Bajocian-Bathonian stage in general. References | Related Articles | Metrics

STRUCTURE-STRATIGRAPHY ASSEMBLAGE CHARACTERISTICS IN TARIM BASIN Zhang Shouan, Li Demao, Han Ping, Xia Zunyi 1998, 19 (4):  299-302.  Abstract ( 129 )   PDF (200KB) ( 212 )   Save Tarim basin is the biggest superimposed composite petroliferous one in inland China.According to the characteristics of structure and sedimentation of Tarim basin, it can be divided into three assemblages i.e.pre-Sinian basement structure-stratigraphy, Sinian-Lower Permian marine craton basin structure-stratigraphy, and Upper Permian-Middle Cenozoic foreland basin structure-stratigraphy.Pre-Sinian basement features are different in northern and southern Tarim basin.The former consists of slightly metamorphic rock of Middle-Upper Proterozoic, while the latter is composed of mixed gneiss and granulite of pre-Sinian.Such difference causes the difference in structure-stratigraphy assemblage in caprock.Sinian-Early Permian is developing period of marine craton basin.The plate rifted in Sinian to form Kuluketage-Maggar aulacogen.In Early Cambrian to Ordovician and Carboniferous, two major transgressions occurred and hydrocarbon-enriched carbonate formation deposited.Late Permian to Mesozoic and Cenozoic is developing period of foreland basin, late Hercynian movement made southern Tianshan Mts uplift entirely to form Kuqa foreland basin in which mega-thick coal-bearing clastic formation were formed. References | Related Articles | Metrics

SEDIMENTARY CHARACTERISTICS AND HYDROCARBON-BEARING SIGNIFICANCEOF FAN DELTA IN TURPAN-HAMI BASIN Zhang Wenchao, Zhao Yan, Li Shengming, Zheng Xian, Tan Yundong 1998, 19 (4):  303-307.  Abstract ( 111 )   PDF (240KB) ( 283 )   Save Based on comprehensive analyses of lithology, electrical property, sedimentary structure, rock texture and oil-bearing characteristics of borehole section and surface outcrop, it is considered that sandy conglomerate reservoir in northern Turpan-Hami basin is of fan-delta origin, which is characterized by close provenance, coarse debris, shallow facies belt and low composition maturity.The sediments are dominated by drag flow.It is subdivided into three subfacies (fan-delta plain, fan-delta front and profan-delta)and nine microfacies.Facies model was established.It is suggested that braided channel of fan-delta plain and underwater channel of fan-delta front possess better reservoir quality and entrapment condition, thereby the target for oil and gas exploration in this area. References | Related Articles | Metrics

STUDY ON VARIABLE WELLBORE STORAGE IN WELL TEST ANALYSIS Jia Yonglu, Yang Xuewen, Guo Jianguo 1998, 19 (4):  308-311.  Abstract ( 95 )   PDF (219KB) ( 234 )   Save The wellbore storage coefficient C is always regarded as a constant in conventional well test analysis.It simplified the model, but made it difficult to undertake data analysis in early period of well test.This paper discussed and summarized the variable wellbore storage in well test analysis in detail, and studied the application of Fiar model and error function variable wellbore storage model.These models enabled i t easier to calculate the divergence in true wellbore di-ameter model when skin factor is negative.Also, i t discussed the effect on formation pressure calculation when taking the variable wellbore storage into account. References | Related Articles | Metrics

SHEAR RATE OF POWER-LAW FLUID THROUGH POROUS MEDIA Wang Xinhai, Zhao Guoping 1998, 19 (4):  312-314.  Abstract ( 133 )   PDF (144KB) ( 394 )   Save Numerical mean shear rate, volume mean shear rate and viscosity mean shear rate have been derived for power-law fluid flow through porous media.Physical meaning of some shear rate expressions has been analyzed.Different shear rate expressions should be used in different cases.Viscosity mean shear rate taking account of permeability reduction should be used in calculating viscosity of polymer solution(aqueous phase)for numerical simulation of polymer flooding. References | Related Articles | Metrics

WHY CHOOSING WATERDRIVE CURVE BY OIL VISCOSITY Yu Qitai 1998, 19 (4):  315-320.  Abstract ( 102 )   PDF (284KB) ( 265 )   Save The derived process of the relationships for water cut (fw)vs.recovery of recoverable reserves (R*)corresponded with waterdrive curve is recommended.It's shown that the relationships of fw vs.R* are a law of water cut raising being representative of essence of displacement characteristics in waterflooding reservoi rs.The fw —R*relationships of previously-recommended 4 waterdrive curves can reflect the different laws of water cut raising, i.e.Nazarov curve, Maksimov-Tong curve, Sipachev curve and Sazonov curve.It' s shown that oil viscosity is the most important natural control on the law of water cut raising in waterflooding reservoi rs.The principle for choosing waterdrive curves suitable for the actual reservoir is the agreement between the choosed waterdrive curves and water cut raising trend actual reservoirs.The purpose is to look for a waterdrive curve which can make calculation and prediction as early and accurate as possible in a reservoir.It' s demonstrated that to choose waterdrive curves by oil viscosity is helpful to realize this purpose and can avoid blindness in use of waterdrive curves.Finally, the method for determining the limits of oil viscosity (3 and 30 mPa°s)by which the waterdrive curve is choosed by using the Ivanova's fw —R* chart and the relationship between cumulative water-oil ratio (Wp/Np)at R*=1.0 and μo used in China is recommended. References | Related Articles | Metrics

THE EMPIRICAL METHOD FOR PREDICTING DEVELOPMENT INDEX OF OILFIELD Wang Junkui 1998, 19 (4):  321-324.  Abstract ( 73 )   PDF (208KB) ( 192 )   Save The combination of production decline curve with water displacement curve gave a complete set of empirical method for predicting development index of oilfield, which avoided the neglect of watercut in production decline curve prediction and the neglect of time in water displacement curve prediction. It can also be used to predict the remaining development life of oilfield and oil recovery rate when it is abandoned.Case study showed that high watercut stage is an important period of oilfield development. It is suggested that we should take quite more care of the estimation of recoverable reserves with production decline curve because it is always overestimated. References | Related Articles | Metrics

A NEW MODEL FOR PREDICTING PRODUCTION AND RECOVERABLE RESERVEOF OIL AND GAS FIELD Zhu Shengju 1998, 19 (4):  325-328.  Abstract ( 94 )   PDF (176KB) ( 180 )   Save Based on Γ(x2)distribution in probability statistics, a new model was presented for predicting production, recoverable reserve, maximum annual production and the time when it will occur.Case study showed that this model is practical, and the prediction is quite reliable. References | Related Articles | Metrics

DEVELOPMENT PRACTICE OF UNTABULATED RESERVOIR IN LAMADIAN-SAERTU-XINGSHUGANG OILFIELD Liu Chunlin, Sun Guangsheng, Wang Qingxia 1998, 19 (4):  329-331.  Abstract ( 105 )   PDF (153KB) ( 151 )   Save The untabulated reservoir is composed of argillaceous siltstone, silty mudstone and calcareous siltstone with the dominance of oilstain in Lamadian-Saertu-Xingshugang oilfield.It is of the same river delta origin with the tabulated reservoir.Laboratory study and development practice showed the untabulated reservoir is of commercial value under the current development technique.This paper mainly discussed the hydrocarbon-bearing structure characteristics and potential, gave the development technology and measure for quantatitively developing untabulated reservoir.These can be referred for the development and adjustment of Lamadian-Saertu-Xingshugang oilfield. References | Related Articles | Metrics

THE MINIMUM AND REASONABLE SUBMERGENCE DEPTH IN EXTRA HIGH WATERCUT STAGE IN SHUANGHEOILFIELD Yang Kun, Xing Yu, Lu Jun, Li Guoqiang 1998, 19 (4):  332-333.  Abstract ( 129 )   PDF (157KB) ( 191 )   Save Based on the current development characteristics in Shuanghe oilfield, the minimum submergence depth of each development unit was given by using the principle of reservoir engineering.Additionally, the reasonable submergence depth was presented according to actual production data.These offered the basis for reasonable downhole tubular design. References | Related Articles | Metrics

THE DEVELOPMENT OF THEORETICAL CHART OF WATER-CONSUMPTION-INDEX AND ITS APPLICATION IN WATERFLOODING OILFIELD Sun Jiwei, Sun Jianping, Sun Laixi, Xie Yunlong, Xu Xuepin 1998, 19 (4):  334-335.  Abstract ( 79 )   PDF (157KB) ( 209 )   Save Based on the basic concept of water-consumption-factor in oilfield development, water-consumption-index was defined as water-consumption-factor with injection-production-ratio of 1.Combined with water displacement curve given by Tong Xianzhang, the relationship between water-consumption-index and recovery percent was derived by which the theoretical chart of water-consumption-index was developed.It can be used to evaluate water flood performance and predict recovery factor.The chart is simple and easily understood, which performed well in Shuanghe oilfield. References | Related Articles | Metrics

A NEW METHOD FOR EVALUATING THE RESERVOIR QUALITY OF HIGH-POROSITY AND HIGH-PERMEABILITY SANDSTONE RESERVOIR WITH SEM Yang Hui, Jin Jiangchao, Wei Guangzhen 1998, 19 (4):  336-337.  Abstract ( 86 )   PDF (130KB) ( 184 )   Save Based on the plane model of pore-throat of sandstone and pore diameter, throat width and percentage pore area from image processing of scanning electric microscope(SEM), apparent permeability formula for characterizing sandstone reservoir quali ty was derived.The calculation were correlates well with true permeability. References | Related Articles | Metrics

EVALUATION OF FRACTURING EFFECT WITH FRACTURING FLUID WITHDRAWAL DATA Huang Qiuwei, Li Xuebin 1998, 19 (4):  338-341.  Abstract ( 71 )   PDF (172KB) ( 196 )   Save Based on fracturing fluid withdrawal data in Xiaoguai oilfield, i ts characteristics were summerized, and Cl- —Qp curve prepared for predicting oil/water layer.Furthermore, the parameters of fracturing fluid withdrawal were presented to identify formation deliverability, permeability, fracture conductivity and post-fracturing formation damage and to quali titively evaluate fracturing effect and determine the reason of low production of oil well.All these offer basis for drawing up next development project. References | Related Articles | Metrics