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01 December 1998, Volume 19 Issue 6 Previous Issue    Next Issue

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WEATHERING CRUST MODEL OF CARBONIFEROUS VOLCANIC ROCK IN HINTERLAND OF JUNGGAR BASIN Zhang Nianfu, Cao Yaohua, Kuang Jun, Lin Jinfeng 1998, 19 (6):  450-452.  Abstract ( 138 )   PDF (158KB) ( 215 )   Save Volcanic rock weathering crust of Carboniferous is the important target for deep oil/gas exploration in hinterland of Junggar basin, which can be divided into sedimentary caprock belt(A), upper weathering crust(B), lower weathering crust(C)and tight volcanic rock belt(D)from top to bottom based on petrology and petrophysical properties of volcanic rock weathering crust from more than 50 wells.Effective pore space exists in B and C belts. According to pore origin of volcanic rock reservoir and its contact with overlying and underlying source rocks, volcanic rock weathering crust in Carboniferous can be divided into four models :①no source rock exists above and below volcanic rock, dominated by freshwater leaching pore ;②source rock occurrs above volcanic rock dominated by freshwater and organic acid denudation pores ;③source rock occurrs below volcanic rock dominated by freshwater denudation pore in upper weathering crust and by organic acid denudation pore in lower weathering crust;④source rock occurrs above and below volcanic rock with co-existence of freshwater and organic acid denudation pores.The study showed that volcanic rock weathering crusts in Carboniferous in Mosuowan anticline, Muhu anticline, Manan anticline and Baijiahai arch identified as the fourth model, are the important targets for oil/gas exploration. References | Related Articles | Metrics

ON BASEMENT OF YANQI BASIN Wu Fuqiang, Chen Wenli, Cao Jiankang, Duan Xinjian 1998, 19 (6):  453-457.  Abstract ( 162 )   PDF (257KB) ( 234 )   Save Based on gravity, magnetic, electric, drilling and geologic data of peripheral basin, basement of Yanqi basin in Mesozoic and Cenozoic were classified into four structural types: imbricate, ramp, back thrust and basement arch.The lithology includes Proterozoic catametamorphic rock in south margin, granite in Hercynian period in northern margin, Mid-Upper Carboniferous epimetamorphic rock in Sishilicheng sub-sag and Mid Devonian epimetamorphic rock to the north of Yannan fault.The lithofacies belt extends from east to west, and is zoned axially.The basement is of Tarim platform to the south of Zhongmachang fault and of Hercynian fold to the north.The latter probably form anticlinal trap in the caprock due to its higher compressibility and unstability.The caprock has higher organic maturity resulting from deeper geothermal flow, so oil and gas are enriched in northern Yanqi basin, which is evidenced by the fact that the discoveries so far took place in northern Yanqi basin. References | Related Articles | Metrics

OIL/GAS RESERVOIR FORMATION CONDITION IN LUKEQUN ARC-LIKE BELT Tu Xiaoxian, Liang Hao, Huang Weidong 1998, 19 (6):  458-461.  Abstract ( 117 )   PDF (203KB) ( 221 )   Save On the basis of analyses of structure evolution, distribution and pore evolution of reservoir, oil-source correlation, reservoir formation time and thickening mechanism of viscous oil in Lǜkeqǜn arc-like belt, Turpan-Hami basin, it is considered that Tuyuke heavy oil formed in Early Jurassic, along with superior structure and reservoir quality; the thickening of crude oil is related with viscous oil expelled in low maturity period, and more importantly, with degradation of anaerobic bacteria and escape of light composition.Therefore it is reasonable to suggest that Lǜkeqǜn arc-like belt is an important target for heavy and light oil exploration in pre-Jurassic in Turpan-Hami basin. References | Related Articles | Metrics

THE RELATION AMONG POROSITY, SHALINESS AND P- AND S-WAVE VELOCITY OF SEISMIC WAVE Huang Kai, Yang Xiaohai, Xu Qunzhou, Lai Zhongkang, Zhang Lufei 1998, 19 (6):  462-464.  Abstract ( 127 )   PDF (208KB) ( 344 )   Save The velocity of seismic wave and P-and S-wave velocity ratio are controlled by many factors.Therefore porosity obtained from Wyllie and Pickett formula has limitations and errors.To overcome these problems, 69 rock samples in western Junggar basin were selected and shaliness of clastic rock measured on thin section.Moreover, P- and S-wave velocity of rock samples saturated with oil and water were measured in lab.The results showed that velocity of seismic wave and P- and S-wave velocity ratio are direct proportion to porosity and shiliness of rock ;while veloci ty of seismic wave is more sensitive to porosity than to shaliness, and both parameters are more sensi tive to shaliness of sample saturated with water than to that of sample saturated with oil.This result has guidance to lateral prediction of reservoir. References | Related Articles | Metrics

LOG RESPONSE AND INTERPRETATION OF VELCANIC ROCK RESERVOIR Dai Shihua, Luo Xingping, Wang Jun, Jiang Shuyun 1998, 19 (6):  465-470.  Abstract ( 94 )   PDF (228KB) ( 234 )   Save Lithology and lithofacies of volcanic rock are very complex, which control reservoirs characteristics. Seven geophysical methods are available for comprehensive study of volcanic rock, while 5 are useful for identification of lithology and lithofacies of volcanic rock.Calculation of reservoir parameters with the established model from the selected framework parameters of different lithologies can improve the accuracy of log interpretation, thereby favoring volcanic rock reservoir evaluation. References | Related Articles | Metrics

PREDICTION OF ALLUVIAL FAN RESERVOIR ON SLOPE IN NORTHWESTERN MARGIN OF JUNGGAR BASIN Lei Dewen, Lu Huantong, Liu Zhenyu, Zeng Jun 1998, 19 (6):  471-472.  Abstract ( 107 )   PDF (179KB) ( 296 )   Save Upper Permian and Lower Triassic in northwestern margin of Junggar basin are important oil productive zones, with sedimentary facies dominated by alluvial fan.As the traditional saying goes “where there is alluvial fan, there is oil or gas”, it is therefore essential to predict the distribution of alluvial fan.The alluvial fan in this area can be classified into fault-cliff fan and talus fan.In accordance with their characteristics, seismic stratigraphy was successfully used to predict i t in recent years, which included the study of the distribution of fault line and pinchout line, seismic facies analysis, interval velocity analysis, quantitative analysis of property, well constrained inversion and interpretation. Six alluvial fans and their facies belt distribution were proved, ten appraised well location were determined, and the commercial oil flow has been obtained in seven appraised wells at present. References | Related Articles | Metrics

CHANGE OF m, a, n AND b VALUES UNDER DIFFERENT TEMPERATURES AND PRESSURES Zhao Fazhan, Cai Minlong 1998, 19 (6):  473-475.  Abstract ( 126 )   PDF (138KB) ( 197 )   Save Calculated cementation index(m), saturation index(n)and formation constants(a, b)from the measured resistance increasing rate and formation factor under high temperature and high pressure are different from those under ambient conditions.Study showed that it results from different electrical conductivity of ions under different temperatures. Moreover, it is pointed out that the parameters measured at ambient conditions must be corrected for log interpretation. References | Related Articles | Metrics

THERMAL EVOLUTION CHARACTERISTIC OF ORGANICMATTER OF LOWER CRETACEOUS SOURCE ROCK IN ERLIAN RIFT SYSTEM Fang Jie, Hou Fengxiang, Sun Tongtong, Liu Jingqiang, Liu Jingwang, Pan Chunnian 1998, 19 (6):  476-479.  Abstract ( 92 )   PDF (215KB) ( 294 )   Save Erlian rift system consists of more than50fault-depressions, major source layer is in Bayanhua group of Lower Cretaceous.Subjected to same regional tectonic event, fault-depression group has similar structure evolution history, also independent sedimentary unit distinguished from each other.Post-rifting regional uplift resulted in low maturity of source rock, wide difference from each other.Comparison of regional geothermal fields, analysis of organic geochemistry exhibi ted thermal evolution characteristics of organic matter in each fault-depression, established hydrocarbon-generation model, summarized the extent of oil formation zone, hydrocarbon-generation potential of source rock in three different fault-depression of Erlian rift system.Furthermore, it is pointed out that Ⅰ -type fault-depression enriched in oil is the most favourable target for oil/gas exploration. References | Related Articles | Metrics

DISCOVERY OF MARINE FOSSIL AND ITS INDICATIVE SIGNIFICANCE IN UPPER PERMIAN, SANTANGHU BASIN Kong Fanjun 1998, 19 (6):  480-484.  Abstract ( 141 )   PDF (186KB) ( 227 )   Save Acerrotrupa and Hyolithes etc.were discovered for the first time in Upper Permian of Santanghu basin in 1994.After studying Paleontology, geochemistry and sedimentology, it is considered that the sedimentary environment of study area is offshore pericontinental lake in Late Permian.These offered new information for studying sedimentary environment, regression time and direction in Late Paleozoic in northern Xinjiang. References | Related Articles | Metrics

PORE STRUCTUREOF LOW-POROSITY AND LOW-PERMEABILITY RESERVOIR IN BAOLANG OILFIELD, YANQI BASIN Zhang Renxiong, Deng Zhizhan, Mao Zhongyuan, Li Xiaomei 1998, 19 (6):  485-489.  Abstract ( 93 )   PDF (204KB) ( 207 )   Save Pore structure of low-porosi ty and low-permeability reservoir in Baolang oilfield, Yanqi basin was examined with conventional mercury injection, directed horizontal flow mercury injection at overburden pressure, cast thin section and image analysis.Pore-throat combination was divided into four modes:medium pore and medium-fine throat, medium pore and fine throat, small pore and tiny throat, and small pore and mini throat.Pore structure is characterized by coarse skewness of throat, fine skewness of pore, high pore-to-throat ratio, medium-toward-poor throat sorting and good pore sorting.Overburden pressure has a strong influence on permeability and pore structure. References | Related Articles | Metrics

SEDIMENTARY CHARACTERISTIC OF KANGKELIN FORMATION IN SHAJINGZI AREA, AKSU, TARIM BASIN Xiao Chuantao, Li Luozhao, Jiang Yanwen, Li Yibin 1998, 19 (6):  490-492.  Abstract ( 94 )   PDF (185KB) ( 247 )   Save Kangkelin formation in Shajingzi area is mixed carbonate and terrigenous clastic sediments in Late Carboniferous -Early Permian, in terms of relative content and texture characteristic, sediments occurred in following eight types:①clastic rock intercalated with limestone ;②clastic rock interbedded with limestone ;③limestone intercalated with clastic rock ;④terrigenous clastic scattering in carbonate matrix ;⑤carbonate as cements in clastic rock ;⑥carbonate intraclasts distributed in terrigenous clast ;⑦mixed terrigenous gravels and carbonate intraclast sediment;⑧terrigenous gravel and carbonate intraclasts scattering in carbonate matrix.Based on the analysis of formation mechanism of mixed sediment, it is suggested that the type of mixed sediment is controlled by sealevel changes, and carbonate sediments have close relation to rising of sea level. References | Related Articles | Metrics

RESERVOIR CHARACTERISTIC OF XISHANYAO FORMATION OF MIDDLE JURASSIC IN NIUJUANHU OILFIELD, SANTANGHU BASIN Tang Yong 1998, 19 (6):  493-497.  Abstract ( 115 )   PDF (227KB) ( 244 )   Save Fan-delta distributary channel sand body is framework one of Xishanyao reservoir(Middle Jurassic)in Niujuanhu oilfield.The petrology of reservoir is characterized by low structural and compositional maturity.The lithology is feldspar-lithic sandstone and lithic sandstone.It has severe vertical heterogeneity, and can be classified into three members based on cyclic and vertical changes of petrophysical properties.Reservoir space is dominated by primary intergranular pore and secondary intergranular denudation pore, characterized by small pore and fine throat, small pore and tiny throat, fine skewness and poor sorting.Reservoi rquality is controlled by compaction, cementation and dissolution in A period of Late diagenetic period.There is better correlation between macro petrophysical parameters and micro structural parameters.Comprehensive evaluation indicated that two members in upper part are medium-bad reservoir, while lower member has no reservoir quality.Sensitivity analysis showed that the reservoir is strongly water-sensitive. References | Related Articles | Metrics

STRATIGRAPHIC CLASSIFICATION AND CORRELATION OF CARBONIFEROUS AND PERMIAN IN WESTERN TARIM BASIN Ding Yaochao, Yang Pin 1998, 19 (6):  498-501.  Abstract ( 178 )   PDF (169KB) ( 280 )   Save Carboniferous and Permian in western Tarim basin were divided into three zones and six subzones. Thirty-six fossil belts or assemblages including fusulinida, condonts, forminifera, ostracodas and sporopollen were established, new stratigraphic classification plan was drawn up to provide reliable basis for petroleum prospecting and downhole stratigraphic classification and correlation. References | Related Articles | Metrics

APPLICATION AND DERIVATIONOF HUBBERT'S QUADRATIC FUNCTION Chen Yuanqian 1998, 19 (6):  502-506.  Abstract ( 165 )   PDF (227KB) ( 440 )   Save Hubbert's model may be used to predict production rate, cumulative production rate and recoverable reserves of oil and gas.However, he first assumed that the production rate Q or dNp/dNt can be expressed as quadratic function of cumulative production rate Np, namely Q=ANp +BN2p.The relationship is derived in this paper, based on the result of reference, and reappeared the derivation of Hubbert's model. References | Related Articles | Metrics

APPLICATION OF ZHANG’S WATER DRIVE CURVE AND ITS CHARACTERISTICS OF OIL-WATER SEEPAGE FLOW Yu Qitai 1998, 19 (6):  507-511.  Abstract ( 106 )   PDF (209KB) ( 245 )   Save The application of a new generalized water drive curve proposed by Zhang jinqing, Wp/Np =-a +b(Wp/N2p), shows that its shape is simple, to obtain its parameters is easy, characteristics for reflecting different laws of water cut raising are very good, for adjustment of oilfield it is sensitive and its applicability is wide, is the best one so far .Its advance has great theoretical sense and useful velue .A method for calculating recoverable reserves year by year using the water drive curve has been proposed .The formula of characteristics of oil-water seepage flow according to the water drive curve has been derived .So the study for the water drive curve become more complete and more overall . References | Related Articles | Metrics

DETERMINATION OF MINIMUMFORMATION PRESSURE MAINTENANCE IN MATURE WATER-DRIVE SANDSTONEOILFIELD—An example from Shuanghe oilfield Yang Kun 1998, 19 (6):  512-514.  Abstract ( 106 )   PDF (201KB) ( 288 )   Save In the light of continuous rising of watercut and decrease of formation pressure in mature heterogeneous sandstone oilfield, injection-production ratio must be adjusted above the reasonable lower limit of formation pressure so that better economic benefit can be obtained.A method for solving minimum formation pressure was given based on theory of oil production technology and production data in Shuanghe oilfield and performed well.It is showed that minimum pressure maintenance may be used as the basis for comprehensive adjustment in later period of oilfield development. References | Related Articles | Metrics

A NEWMETHOD FOR FORECASTING DEVELOPMENT INDEX OF GAS RESERVOIR Wang Bin, Tang Chengfeng 1998, 19 (6):  515-517.  Abstract ( 79 )   PDF (174KB) ( 177 )   Save Systematic well test data of gas well showed that indicative curve is a straight line when bottomhole pressure exceeds a certain value, but a quadratic curve when bottomhole pressure is less than this value.Based on above-mentioned and performance data of gas reservoir, the method for forecasting development indexes of gas reservoir was derived.It can be applied in sandstone and conglomerate gas reservoir with midium-low permeability and recovery factor of more than 5%, which performed successfully in Upper Wuerhe gas-cap gas reservoir in area Well Ke 75, south District No.5 in Karamay oilfield.Compared with numerical simulation, it is simpler and has more reliable result. References | Related Articles | Metrics

THE RELATIONSHIP BETWEEN OVERBURDEN PRESSURE, FLUID PRESSURE AND FRAMEWORK STRESS Li Chuanliang 1998, 19 (6):  518-519.  Abstract ( 179 )   PDF (120KB) ( 248 )   Save Traditional theory considered that the overburden pressure(pob)is the sum of hydrostatic pressure(pf) and framework stress(pG), this may resulted in many mistakes.Taking petrophysical properties and mechnic equilibrium into account, a new expression was established, namely pob =Φpf + (1 -Φ) pG.It is more scientific and expected to play important role in reservoir engineering and lab study. References | Related Articles | Metrics

PILOT TEST OF NAPHTHENATE ADDITIVE IN HEAVY OIL THERMAL RECOVERY Sun Xinchun 1998, 19 (6):  520-530.  Abstract ( 87 )   PDF (197KB) ( 244 )   Save The technology of salt production from the vaccum fraction(distillation range 300 ~ 490 ℃) —naphthenic acid at Karamay Petrochemical Plant was examined, together with the EOR performances of naphthenate additive in steam stimulation process.The results showed that salt production is easily operated, cheap and fully meets the technical requi rements for the additives in thermal recovery.Based on laboratory research results, 90 t naphthenate has been available by trial production.Pilot test of naphthenate additive injection into 18 thermal-recovery wells was undertaken in the heavy oil productive area operated by No.1 Oil Production Plant.The results are as expected.Among them, 12 wells have a total additional production of 1 644 t, with input-output ratio of 1∶4.It is suggested that naphthenate is a novel effective and cheap surfactant for thermal heavy oil recovery. References | Related Articles | Metrics