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2001 Vol. 23, No. 4

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PETROLEUM SYSTEM AND OIL EXPOLRATION IN THE WEST LISHUI SAG, THE EAST CHINA SEA BASIN
JIANG Liang, WANG Yi, JIN Qiang
2001, 23(4): 368-372. doi: 10.11781/sysydz200104368
Abstract(720) PDF-CN(587)
Abstract:
The West Lishui Sag is located in the north of the Taibei Depression,the East China Sea Basin.Its source rocks and rese rvoir rocks are dark shales and sandstones in the Mingyuefeng Formation(E1m)and the Lingfeng Formation(E1l)of the Lower Tertiary.The sag was believed as an oil and gas domain by petroleum geologists.A deeper petroleum system(E1y-E1l)and a shallow complex petroleum system(E1m-E1w)were identified in the West Lishui Sag.The relationship between source rocks and hydrocarbon accumulation was discussed,and a model of hydrocarbon migration wa s postulated.The petroleum distribution in this sag was clearly defined and po tential targets for prtroleum exploration were pointed out.So that this study w as applicable to hydrocarbon exploration in the Easy China Sea Basin.
STUDY ON THE NATURAL GAS ACCUMULATION MODELS AND STRUCTURE OF THE YINGGEHAI BASIN
HE Jiang-qi, WANG Yan
2001, 23(4): 373-377. doi: 10.11781/sysydz200104373
Abstract(1050) PDF-CN(266)
Abstract:
The Yinggehai Basin was developed on the base of the seaward extended part of the Red River Rift zone controlled by the double mechanisms of mantle-uplift extension and strike slipping along the Red River Rift.It has rift-depression dual structure.The evolution of the Yinggehai Basin has experinced rift and depression formation two stages.During different evolutionary stages,thermal subsidence and the Red River rifting played different parts.The Yinggehai Basin has the central diapir zone and the Yingdong slope zone two natural gas accumulation models.The activities of diapir heat flow provided accumulation places and dynamic conditions for the accumulation of natural gas in the central of the basin,and the natural gas in high-pressure compartments released upward many times by the way of outpouring flowing and then accumulated.On the other hand,the natural gas pools in the Yingdong slope zone were the results of natural gas generated in the deep part of the basin migrated to the slope zone driven by solution convection mechanism and then accumulated in reservoir-cap well-matched positions.
TECTONIC FEATURES OF THE FORELAND OBDUCTION ZONE IN THE HETIAN SAG OF THE SOUTHWEST TARIM DEPRESSION
WANG Shi-hu, XU Xi-kun, SONG Guo-qi
2001, 23(4): 378-383. doi: 10.11781/sysydz200104378
Abstract(833) PDF-CN(317)
Abstract:
The foreland obduction zone of the Hetian Sag is located in the eastern of the Southwest Depression of the Tarim Basin.On the section,it consists of a superimposed anticline double tectosome overlapped by a nappe and many thrust sheets and a weakly deformed autochthon from upper to lower and from south to north.The nappe is 5000-7000m thick,205km long from east to west and 14-43km wide from south to north.Its northward displacement distance is 40-100km.It is a hinge folded anticline related to hanging-wall growth faults,and is controlled by Hetian large-scale step-typed decollement faults.On the lateral border of the nappe,lateral and oblique fault-slope secondary fault-related folded anticlines parallel to boundary faults were developed.On the front margin of it,a series of secondary faults and related folds were generated because the axis plane along the northern limb of the nappe anticline fractured.Within the internal of the nappe,rolling changes took place along the WE-direction axis,and anticline traps were formed.Under the nappe,the weakly deformed E-inclined slope,the Piyaman sumperimposed fault-slope anticline-typed double structure,the Sangzhu triangular-zone structure and the imbricate thrust zone were developed successively from east to west.On the section,the imbricate thrust zone is situated below the front margin of the triangular-zone structure,and they are overlapping distributed on plane.
RESERVOIR CHARACTERISTICS OF THE JURASSIC DOLOMITE IN THE QIANGTANG BASIN
ZHANG Li-qiang, JI You-liang, LI Yong-tie
2001, 23(4): 384-389. doi: 10.11781/sysydz200104384
Abstract(607) PDF-CN(321)
Abstract:
The Jurassic dolomite is widely distributed in the Qiangtang Basin.It can be divided into dolomicrite,residual-grain dolomite and crystal grain dolomite three rock types.The former two are often adjacent or asso-ciated to gypsum,and the latter one has nothing to do with gypsum.In the postsedimentary changs,many kinds of diagenetic reconstruction have taken place,Among them,those which have some influences on the accumulation features of dolomite mainly include dissolution,recrystallization and tectonic stress processes.The major accumulation spaces of dolomite in the study area are intercrystal pores,intercrystal solution openings and tectonic fissures.Fine-coarse crystallized dolomite has good accumulation petrophysical properties,and is a kind of good-well reservoir.
OIL RESERVOIR TYPES AND THEIR CONTROLLING FACTORS IN LINGYANDING REGION, THE NORTHWEST ORDOS BASIN
ZHOU Rui, HU Xue-zhi
2001, 23(4): 390-394. doi: 10.11781/sysydz200104390
Abstract(665) PDF-CN(362)
Abstract:
In this paper,the oil reservoirs in the Middle-Lower Jurassic Yan'an Formation and the Upper Triassic Yanchang Formation of Lingyanding region,the Northwest Ordos Basin are classified into five types,that is,the tectonic-lithologic composite oil reservoir,the top-changing screened oil reservoir,the strata overlapping oil reservoir,etc.The characters of various oil reservoirs of different types are expounded.It is pointed out that the oil resservoirs in the study area are dominated by the composite type.Combined with tectonic location where each type of oil reservoir situated as well as paleogeomorphic forms and lithofacies features,the influences and controlling action of different sedimentary facies and different types of tectonics on the formation of oil reservoirs are also discussed.
ACCUMULATION ANALYSIS ON A HELIUM-ENRICHED GAS RESERVOIR IN HUAGOU AREA, THE JIYANG DEPRESSION
CAO Zhong-xiang, CHE Yan, LI Jun-liang, LI Hong-wen
2001, 23(4): 395-399. doi: 10.11781/sysydz200104395
Abstract(608) PDF-CN(430)
Abstract:
Helium content in natural gas reservoirs is very low,usually smaller than 0.1%.Gas helium not only has inmportant industrial values,but also is a major differential mark for the origin of natural gas especially nonhydrocarbons natural gas.In Hua-501 gas reservoir discovered in the Upper Tertiary Minghuazhen Formation(Nm)of Huagou area,the Jiyang Depression,the gas He content is up to 3.08%.The gas components of the gas reservoir is complex.It has not only nonhydrocarbons gas layers dominated by N2and CO2,but also gas layers dominated by CH4.It is a special gas reservoir of multiple and composite origins.δ13CCO2 is equal to-8.3‰,and 3He/4He is 4.47×10-6.These representative indexes reveal that N2,CO2,He and other nonhydrocarbons gases are mainly of mantle-source origins.δ13 Cl is equal to -48.8‰.This shows that gas CH4 is organic genetic oil-type gas generated in the Lower Tertiary.The gas reservoir is located in the joint of the Jiyang Depression and the Luxi Uplift.It is controlled by the Gaoqing Fault which is a deep and large rift long activated since the Mesozoic,and is closely related to muti-stage magmatic activities.CH4 gas layers and N2,CO2,He and other nonhydrocarbons gas layers are the products of two stages of accumulation.CH4 accumulated early,and the accumulation of helium-enriched nonhydrocarbons gases happened within 3Ma from now.
PREDICTION AND EVALUATION OF GAS RESERVOIRS IN THE LOWER SHAXIMIAO FORMATION OF XINCHANG GASFIELD, WEST SICHUAN PROVINCE
LÜ Zheng-xiang, QING Chun, ZENG Xiao-ying
2001, 23(4): 400-402407. doi: 10.11781/sysydz200104400
Abstract(584) PDF-CN(217)
Abstract:
The gas pool in the Lower Shaximiao Formation of Xinchang gasfield is another gas-bearing interval discovered recently in the distal gas reservoirs of tight clastic rock in West Sichuan province.By study on the geophysical properties of gas-bearing sandbodies and the basic geological characteristics of the gas pool in this paper,it is summarized that the control factors of natural gas enrichment for this gas pool are mainly reservoir sedimentary microfacies and gas-bearing sand bodies show the negative reflection seismic response features of medium-strong amplitude and low impedance.Based on the acknowledge of gas pool characteristics,the gas pool is predicted and evaluated combined with favorable reservoir microfacies distribution,seismic response and other characteristics.
MIGRATION MODELS OF HYDROCARON FLUIDS IN THE DONGYING DEPRESSION——EVIDENCES FROM BOILING FLUID INCLUSIONS
QIU Nan-sheng, ZHANG Shan-wen, JIN Zhi-jun
2001, 23(4): 403-407. doi: 10.11781/sysydz200104403
Abstract(796) PDF-CN(259)
Abstract:
Boiling fluid inclusions were identified in the hydrocarbon reservoirs of the Dongying Depression.These inclusions were found first time in the rift basins of China,and it provided very important evidences for the pulsatile-or paroxysmal-typed entrapment of underground hydrocarbon fluids.In this paper,the characteristics of boiling fluid inclusions in the study area and their relations to the entrapment of hydrocarbon fluids are introduced,and the paroxysmal-typed entrapment model of hydrocarbon related to faults and sandstone lens are discussed,respectively.
HYDROCARBON ACCUMULATION AND DISTRIBUTION IN FAULT BASINS
FU Guang, YANG Mian
2001, 23(4): 408-411. doi: 10.11781/sysydz200104408
Abstract(677) PDF-CN(255)
Abstract:
Based on analysis of fault basin types and their characteristics of secondary structures,the types of hydrocarbon accumulation and their distribution in time and space were summarized,and four models for hydrocarbon reserviors in fault basins were suggested.Furthermore,different reserviors developed in different secondary structure zones of fault basins were showed.
FRACTURE DEVELOPMENT OF TUFF RESERVOIRS IN THE HANAN AREA OF THE ERLIAN BASIN
LIANG Guan-zhong
2001, 23(4): 412-417. doi: 10.11781/sysydz200104412
Abstract(657) PDF-CN(354)
Abstract:
In view of characteristics of tuff reservoirs,the electric response,resevoir space and type and development of reservior were studied;the development and distribution of fractures and their influential factors were analysed;and influence of fractures on reservoirs and producing formation was discussed.It showed that the play Ⅱ of intermediate tuff developed in wheathering zone of buried-hills of the eastern area possessed good fractures and reservoirs,where was the habitat of principle hydrocarbon accumulation.The fractures provided suitable reservoir space and passway for hydrocarbon migration,so oil and pools were formed.
CAPPING OF THICK MUDSTONES AND ITS RELATIONSHIP WITH OIL AND GAS IN THE NANPU DEPRESSION
WANG Jia-hao, WANG Hua, WANG Gen-fa
2001, 23(4): 418-423. doi: 10.11781/sysydz200104418
Abstract(668) PDF-CN(411)
Abstract:
There are five sets of thick mudstones with wide distribution and low sediment change in the Lower Tertiary of the Nanpu Depression,which were deposited in medium-deep lake environment.The mudstones show efficient capping on thermal flux and hydrocarbon fluid,which results in development of high paleogeothermal gradient,high salinity and deep corrosion in the interior of mudstones and underlying formation.It is the main cause for formation of overpressure.Some lithologic hydrocarbon pools can be formed in the thick mudstones.As a result of its capping,thermal evolution of organic matter in abnormal belts was enhanced and hydrocarbon was generated.Deep corrosion accelerated forming of secondary pores in sandstones in the abnormal belt,so physical properties of reserviors was improved.A reasonable prediction of overpressure based on abnormal hydrothermal fluid activity in Beipu-Laoyemia area provided important guide for hydrocarbon exploration in the area.
EFFECT OF INJECTING WATER DEVELOPMENT ON MICROSTRUCTURE OF RESERVOIRS IN GUDAO OILFIELD
LI Ji-hong, QU Zhi-hao, CHEN Qing-hua
2001, 23(4): 424-428. doi: 10.11781/sysydz200104424
Abstract(655) PDF-CN(350)
Abstract:
On the basis of information of rock sections,cast sections,ESM and mercury injection curves etc.,a systematic study on the characteristics of microstructure of reservoirs in the Guantao Formation of Gudao oilfiele during different development periods was given.The results show that the microstructure has been improved by water-injecting development.
A STUDY OF WATER SENSITIVE INDEXES DURING OIL FIELD DEVELOPMENT
SUN Li-juan, QIAO Guo-an, ZOU Xing, SHEN Hui-ping, GUAN Fei, CHEN Li-yue
2001, 23(4): 429-432. doi: 10.11781/sysydz200104429
Abstract(727) PDF-CN(305)
Abstract:
The study of water sensitive indexes may effectively influence development of an oil field.By comparing the experimental data of water sensitivity in Wennan oil field,a relationship among water sensitive indexes,rock air permeability and salinity of injected water was set up.It is showed that there was very high level of association with each other.The relational expression can be used to predict the possible water sensitivity of different rocks and different injected water in the area.It may also have some indication for other oil fields during waterflood development.
STUDY ON THE OIL SOURCE OF CRUDE OILS FROM WELL QUN-5 AND WELL QU-1 IN THE TARIM BASIN-NEW EVIDENCES FROM FATTY ACIDS AND ALKYL CYCLOHEXANES SERIES COMPOUNDS
DUAN Yi, ZHOU Shi-xin, MENG Zi-fang
2001, 23(4): 433-437. doi: 10.11781/sysydz200104433
Abstract(678) PDF-CN(333)
Abstract:
Oils from well Qun-5 and well Qu-1 in the Tarim Basin contain abundant fatty acids and a series of long-chain alkyl cyclohexanes.The compositions of fatty acids are in the range of C10-C26,and exhibit a model distribution with maximum at C16 for oil from well Qun-5 and at C 15 for oil from well Qu-1.Studied data show that these fatty acids come mainly from their source rocks and are derived from algae and bacteria.The compositions of long-chain alkyl cyclohexanes are in the range of C12-C32.They contain a model distribution with maximum at C13 for oil from well Qun-5 and bimodel distributions with maxima at C14,C15 or C19.Significant differences in the distributions of fatty acids and long-chain alkyl cyclohexanes in oils from well Qun-5 and well Qu-1 indicatethat these oils have different oil sources.Together with the features of compositions of carbon isotopes,long-chain tricyclic terpanes,hopanes and steranes,it is suggested that oil from well Qun-5 originate from Cambrian-Ordovician marine carbonate source rock and oil from well Qu-1 originate from Carboniferous marine mudstone source rock.
IMMATURE CRUDE OILS POSSIBLY MAINLY ORIGINATING FROM PRIMARY SOLUBLE ORGANIC MATTER-I. DIRECT EVIDENCES FROM SATURATED HYDROCARBONS
XIA Yan-qing, ZHANG Geng-xin
2001, 23(4): 438-443. doi: 10.11781/sysydz200104438
Abstract(996) PDF-CN(337)
Abstract:
Immature crude oils were found in many places of the world,but their formation mechanism has not been understood clearly.There are now more than five viewpoints on the origin of them.In face,most of immature oils have similar characters,so it is very possible that they were mainly formed by similar ways.In this paper,the results of simulation experiments on Jianghan calcareous mudstone,Green River shale,Fushun oil shale and Nanning lignite samples(collected from cores or orefields)were reported.Under the condition of lower temperature,the saturated hydrocarbons formed by kerogen from these samples are similar to mature oils,and those formed by bulk samples(including kerogen and soluble organic matter)are very similar to immature oils.This proved that immature crude oils possibly are mainly converted directly from primary souble organic matter in sediments.
GEOCHEMICAL ANALYSES ON THE HYDROCARBON COMPOSITION CHANGES AND POOL-FORMING MECHANISMS OF SHUANGNAN OILFIELD IN THE WEST LIAOHE SAG
LI Hong, HUANG Hai-ping, SHI Xiao-ying, MA Kan-chuang
2001, 23(4): 444-451. doi: 10.11781/sysydz200104444
Abstract(676) PDF-CN(327)
Abstract:
Shuangnan area produces mainly normal crude oil along with small amounts of condensate.It is discovered by observation that the total properties of condensate and normal oil(including density,viscosity,wax content,solidifying point,etc.)and the content of some biomarkers change greatly.Detail geochemical analyses reveal that they are well-matched in maturity.Many kinds of biomarkers are used to make maturity evaluation.The matutity of liquid hydrocarbon Ro is equal to 0.7%-0.8%.These crude oils have the same biological source composition,and are formed in the similar sedimentary environments.The total and molecular composition changes of crude oil are attributed to migration-fractionation process.In this process,gas-condensate is partitioned from the related crude oil,and then migrates to shallower reservoirs and accumulates there.It is very important to recognize the migration-fractionation process and understand its effects on petroleum components,because many geochemical bimarkers applied in oil-oil and oil-source correlation as well as crude oil alteration,oil source types,thermal maturity,etc.may be influenced by the migration-fractionation process.
A NEW TECHNIQUE FOR MEASURING ARGON ISOTOPE IN NATURAL GAS
SUN Ming-liang
2001, 23(4): 452-456. doi: 10.11781/sysydz200104452
Abstract(631) PDF-CN(327)
Abstract:
The Ar concentration in natural gases ranges from n×10-4～n×10-5,while that in the air is 9.3×10-3,which is in 2 to 3 orders of magnitude higher than that of the former.Reducing and preventing natural gas Ar being contaminated by atmospheric Ar during sampling in the field and detecting in laboratories is a key technique for the accurate measurement of Ar isotope.Presently there are no perfect above-mentioned techniques at home and abroad.We tried and improved the measurement method several tens of times,and finally we set up a new technique which can prevent natural gas Ar being contaminated by atmospheric Ar and obtained the surprising and convincing analytic results of natural gas Ar isotope.The technique includes sampling using high pressure steel vases,injecting samples under the conditions of high vacuum and low seepage rate,reducing background values of the instrument and preventing the fluctuation of the environment of laboratory.
A PRELIMINARY STUDY ON THE FORMATION MECHANISMS OF NATURAL FRACTURES IN RESERVOIRS:AN EXAMPLE FROM JINGBEI BURIED-HILL POOL, NORTH OF CENTRAL LIAONING PROVINCE
SHAN Ye-hua, GE Wei-ping
2001, 23(4): 457-464. doi: 10.11781/sysydz200104457
Abstract(672) PDF-CN(238)
Abstract:
There are a variety of formation mechanisms for the natural fractures in reservoirs.The fracture distributions produced by different mechanisms are not the same.It is usual that fractures on the whole are formed by many kinds of mechanisms in the same period or in different periods.In this paper,a new train of thought is suggested about evaluation on the formation mechanisms of fractures.Based on geological analyses,various possible formation mechanisms of dominant fractures are put forward,and a ling-typed fracture distribution model to predict initial production first-order approximately is established.Then,the sdution of the model is found according to related production data,and the information used in the evaluation of each mechanism is obaained.The application in Jingbei buried-hill fracture pool reveals that unloading and fault activities are two major formation mechanisms of reservoir fractures in this pool,the formed fractures show relatively even distribution in related range and close,wide and irregular features of fractures are directly related to the strong faulting of mang stages and directions.
APPLICATION OF SEISMIC PHASE ANALYSIS TO THE PREDICTION OF THE TRIASSIC RESERVOIRS IN TAHE AREA, THE TARIM BASIN
ZHOU Xiao-jin, LIU Yi
2001, 23(4): 465-469. doi: 10.11781/sysydz200104465
Abstract(607) PDF-CN(251)
Abstract:
According to seismic phase analysis,the corresponding sedimentary characteristics were studied.The medium-strong amplitude of continuous seismic phase indicates braided deltaic plain deposition,medium amplitude of interrupted seismic phase suggests depositional facies of braided deltaic front,and weak or gap seismic phase means mudstones deposited in shallow lake(or interdistributary bay).On basis of above relationship between seismic phase and depositional facies,distribution of sedimentary facies of the Triassic in Tahe area was discriminated,in accordance with its structural setting the potential lithological traps were indicated.

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