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2004 Vol. 26, No. 6

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TETHYAN PLATE STRUCTURES AND PETROLIFEROUS BASINS IN THE QINGHAI-TIBET PLATEAU
FU Xiao-yue
2004, 26(6): 507-516. doi: 10.11781/sysydz200406507
Abstract(712) PDF-CN(528)
Abstract:
The Tethys in the Qinghai-Tibet Plateau is a complex structural system which is formed by multiple collisions and coherences of five crustal blocks and three plate sutured belts. Due to strong inner-continental convergences since the Cenozoic, the Tethys in the Qinghai-Tibet Plateau presently has the structural kinematic features of two structural knots, three convergence boundaries and two great shear belts. The strong convergence of boundaries combined with inner-continental uplifting, compression-shearing and extension-stripping leaded to a complex and uniform kinematic system, characterized by a thick and hot crust. The petroliferous basins in the Qinghai-Tibet Plateau can be divided into three basic types as the marine compound basin, the superposed basin of marine and continent and the continental overlapped basin etc. These basins have some notable features such as high geothermal field, low formation pressure, tight reservoirs, deep oxidized hydrocarbon boundaries and so on, which were resulted from impressions brought about the recombinations and overriding of multiple petroliferous strata, the reconstruction of multiple structural movements and the activities of hot magma.
EIGHT MAJOR DEPOSITIONAL PROCESSES OF CLASTIC ROCKS AND THEIR PETROLEUM RESERVOIR CHARACTERIZATION
YU Xing-he, CHEN Yong-qiao
2004, 26(6): 517-524. doi: 10.11781/sysydz200406517
Abstract(706) PDF-CN(381)
Abstract:
Comprehensive evaluation, modeling and prediction of petroleum reservoir are always concerned in the oil-and-gas field exploration and development. Moreover, study of reservoir characteristics is related to analysis of depositional facies or microfacies. It revolves occurrence of residual petroleum and sweep efficiency or conformance factor of injectant to find new reservoirs and enhance oil recovery during the stage of reservoir management and development in maturing oil fields, and this is related to the study on reservoirs heterogeneity. The fundamental reason of all these results is the mechanisms forming depositional sandbody-depositional processes. The relationship between depositional process and response of reservoir heterogeneity is for the geologists and petroleum engineers to resolve. Based on the previous research, 8 major depositional processes (vertical accretion, progradation, lateral accretion, overbank accretion, sieve accretion, winnowing accretion, channel filling, and turbidity deposition) have been defined and the sedimentary features, reservoir characteristics, architecture, log and seismic responsibility of the sediments formed mainly by these depositional processes have been described in detail, in order to get a better understanding of reservoir heterogeneity and occurrences of residual petroleum on clastic rocks and to provide basis for analyzing genetic mechanism.
POOL-FORMING ZONALITY OF BIOGASES IN THE CENOZOIC BASINS OF DIAN-QIAN-GUI AREA
LU Huang-sheng, ZHOU Li-qing
2004, 26(6): 525-530. doi: 10.11781/sysydz200406525
Abstract(742) PDF-CN(331)
Abstract:
Under the "land-to-land" collision and matching structural action of the Indian Plate to the Euro-Asian Plate, a series of small intermountain strike-slip and pull-apart basins of the Eocene-Oligocene, the Miocene and the third stage of the Pliocene were formed along large strike-slip fault zones in Guangxi, West Yunnan and East Yunnan-South Guizhou areas during the Himalayan Ⅰ,Ⅱ and Ⅲ episodes. Three stages of the basins developed in three areas had different structural and sedimentary evolutionary characteristics, and resulted in different pool-forming conditions of biogases for the basins of each area. Biogas pools mainly distributed in the Eocene-Oligocene and the Pliocene basins in West Guangxi and East Yunnan-South Guizhou areas. In each basin, controlled by fall velocity, sedimentary facies zones, source rock depth, fault developing density, trap types and stratigraphic denuded degree, biogas pool-forming conditions were clearly different in each zone. Biogas pools distributed in the deep sags and adjacent zones of each basin.
PETROLEUM ACCUMULATION IN THE ORDOVICIAN CARBONATE ROCKS IN THE TAZHONG LOW ARCH OF THE TARIM BASIN
LIU Ke-qil, JIN Zhi-jun, LÜ Xiu-xiang, CAI Zhongxian
2004, 26(6): 531-536. doi: 10.11781/sysydz200406531
Abstract(748) PDF-CN(370)
Abstract:
The Tazhong (middle Tarim Basin) Low Arch is one of the sub-tectonic units of middle harimUplift. It is composed of the Tzl fault zone, the Tz north slope and the middle fault-horst zone.The razhong Low Arch is a long-term successive rise which has experienced 7 periods of evolution. The multi-period rising and subsiding brought up lots of reserve-seal assemblages and abundant traps.The multi-period regional unconformities and major faults provided excellent pathways and locations for petroleum migration and accumulation.The Tazhong Low Arch is favorable for petroleum migration and accumulation.The ordovician system has many petroleum reservoirs in a favorable position.The Tzl fault tectonic zone is the most favorable zone for petroleum accumulation with the Tz north slope as the second and the middle fault-horst zone as the worst.The Tzl fault tectonic zone is still the favorable prospect of future exploration.
TYPES AND CHARACTERISTICS OF TIGHT CLASTIC ROCK GAS POOLS IN THE WEST SICHUAN DEPRESSION
ZHU Tong, YE Jun
2004, 26(6): 537-541. doi: 10.11781/sysydz200406537
Abstract(849) PDF-CN(340)
Abstract:
After years of exploration and development, over 20 tight clastic rock gas pools have been found in different regions and formations in the West Sichuan Depression. However, there is no unified division standard for the types of tight clastic rock gas pool. Based on the achievements of gas pool description and exploration, according to the cause of trap and compaction and pressure, the division standard and method suitable for this region are put forward, thus dividing gas pools into 3 types (structure-lithology, structure-digenesis and structure-fracture) and 5 inferior types. The characteristics of typical pool types are also described.
POTENTIAL ANALYSIS OF THE UPPER PALEOZOIC HYDROCARBON RESOURCES IN THE ZHOUKOU DEPRESSION
QUAN Shu-jin, RAO Dan, KONG Fan-jun, LIU Si-hong, JIANG Yong-fu
2004, 26(6): 542-546. doi: 10.11781/sysydz200406542
Abstract(714) PDF-CN(451)
Abstract:
The Carboniferous-Permian coal measures strata in the Zhoukou Depression have stronger hydrocarbon-generating potential, which process abundant organic matter, rich coal and steady lithology and lithofacies. The obvious character of the depression is secondary hydrocarbon generation. The amount of secondary hydrocarbon generation depends on initial maturity, hydrocarbon-generating potential and final maturity. The places which have better secondary hydrocarbon-generating potential in the Zhoukou Depression are the Tanzhuang-Shenqiu Sag and the Niqiuji Sag. The industrial oil flow was obtained from the Paleogene of well Nan-12 at the Dawangzhuang Structure in the Niqiuji Sag, It indicated that the exploration prospects of coal-derived hydrocarbon in the area was extensive.
STUDY ON POOL-FORMING MECHANISM BY TECTONIC COLLAPSE IN THE DONGYING ANTICLINE OF THE BOHAIWAN BASIN
ZHAO Mi-fu, FENG Chun-li, LIU Ya-li
2004, 26(6): 547-552. doi: 10.11781/sysydz200406547
Abstract(618) PDF-CN(381)
Abstract:
In the Dongying Anticline of the Bohaiwan Basin, hydrocarbon was mainly accumulated in the Dongying and the Guantao formations. And on its eastern and western two sides, i.e., the Xinzhen Anticline and the Xianhe Fault Step Zone, hydrocarbon was mainly accumulated in the Sha-2 Member. Based on the study of hydrocarbon source, accumulation, migration, trapping and preservation conditions, it was considered that the distribution of hydrocarbon pools in the Dongying Anticline was of great differences on the plane from longitudinally, which were closely related to regional structural background, regional cap-rock, fault activities and the time-space matching relations among the three. During the active periods of structures, tectonic collapse resulted in the rapid longitudinal migration of hydrocarbon in wide area, which was characterized by paroxysmal and eventful. As during the calm periods of tectonic activities, most of faults lost the behaviours of passages gradually and hydrocarbon may seep monophasically along a few big active faults. The two mentioned above formed together the complex vertical migration of hydrocarbon in the Dongying Anticline.
EVALUATION ON THE HYDROCARBON POOL-FORMING CONDITIONS OF THE UPPER PALEOZOIC BURIED HILLS IN THE DONGPU SAG OF THE BOHAIWAN BASIN
HU Zong-quan, WANG Chuan-gang, ZHANG Yu-lan, ZHANG Fu-shun, ZHOU Xin-ke
2004, 26(6): 553-556. doi: 10.11781/sysydz200406553
Abstract(681) PDF-CN(451)
Abstract:
Compared with the Jiyang Depression, the Dongpu Sag of the Bohaiwan Basin has the basic conditions of forming buried hill hydrocarbon reservoirs. Under the control of key wells, the developing conditions of source rocks, reservoirs and caprocks were extracted as input parameters, the grade of hydrocarbon shows was used as indicator parameters, and a neural network mathematical model was constructed to evaluate the hydrocarbon pool-forming conditions of the Upper Paleozoic buried hills in various key wells of the Dongpu Sag. By subdividing the distribution areas of the three types of input evaluation parameters, the pool-forming conditions of the Upper Paleozoic buried hills in the Dongpu Sag were predicted on the plane, which showed that the central uplift zone had the best prospects. Well Wengu-2 achieving industrial productivity for the first time in the Upper Paleozoic buried hills in the Dongpu Sag proved the predicting accuracy of the model. The characteristics of the Wengu-2 hydrocarbon pool indicated that the coarse and thick sandstone above coal measures had lower depth, and should be the main target layers of exploration in the Upper Paleozoic.
CHARACTERISTICS OF POOL-FORMING DYNAMICS AND CONDUCTING SYSTEMS IN THE LOWER TERTIARY OF THE TONG-WANG FAULT BELT, THE SOUTH DONGYING SAG, THE BOHAIWAN BASIN
ZHAO Yang, LIU Zhen, SONG Shu-jun
2004, 26(6): 557-561. doi: 10.11781/sysydz200406557
Abstract(643) PDF-CN(476)
Abstract:
The Tong-Wang fault belt is located at the south slope of Dongying Sag, Jiyang Depression. The vertical characteristics of geotemperature and formation pressure system (T-P system) is shown as overpressure multiple T-P system:normal T-P system in the upper formations and overpressure T-P system in the lower formations. The Lower Tertiary in this area is covered by relatively stronger power environment. Structural and stratigraphic reservoirs in this area are mainly controlled by fluid potential, and are distributed at relatively weaker fluid potential place. Lithological reservoirs, not restricted by fluid potential, exist at both relatively weaker and higher fluid potential places. Sand bodies and faults are main (carrying) beds for lateral and vertical oil-and-gas migration, while unconformity is also important for oil-and-gas lateral migration. Ladder-like migration is the distinct characteristics of oil-and-gas migration in the study area.
CONTROL OF STRATA SUPERFACE FORMS TO HYDROCARBON DISTRIBUTION-A CASE STUDY OF THE YANQI BASIN
YANG Xu-sheng, HAO Fang
2004, 26(6): 562-565. doi: 10.11781/sysydz200406562
Abstract(631) PDF-CN(331)
Abstract:
Based on the study of the distribution characteristics of strata superface structures and forms, the Yanqi Basin was divided into slope areas, platform areas and nose areas three basic types. The factual structural superface characteristics of the basin were composed of the three types. Each type played a different part in the hydrocarbon pool-formation of the basin. The platform and nose areas were positive to hydrocarbon pool-formation, and the slope areas were unfavorable. Other factors such as the sufficient degree of oil sources should also be considered. The present hydrocarbon distribution of the Yanqi Basin was limited by its secondary structural belts, and several important hydrocarbon-bearing areas were all located in the structural belts adjacent to oil-generating sags. By study on the relationship between strata superface structural forms and main hydrocarbon distribution, it was considered that the hydrocarbon distribution of the Yanqi Basin had certain relations to the characteristics of strata superface structures, and the noses of the basin stretching form secondary structural belts into depressions played an important role in the accumulation and pool-formation of hydrocarbon from source areas to traps.
DISCUSSION ON SOME GEOLOGICAL CHARACTERISTICS OF RESERVOIRS IN PINGHU OILFIELD OF THE EAST CHINA SEA BASIN
ZHENG Bing, GAO Ren-xiang
2004, 26(6): 566-570. doi: 10.11781/sysydz200406566
Abstract(681) PDF-CN(335)
Abstract:
There are three different types of crude oil in reservoirs of Pinghu oilfield. The oil can be discriminated by obvious geochemical parameters with carbon isotope of aromatic hydrocarbon as the fingerprint marker. The oil was migrated from southwest to northeast and from reservoir H6 in the lower part to reservoir H2 in the top. And hydrocarbon migration was controlled by structural uplift. The reservoirs were well connected, although the light deasphalted action of oil blocked some pores of reservoirs.
MICROSCOPIC MECHANISM STUDY OF GAS-WATER FLOW IN POROUS MEDIA
ZHU Hua-yin, ZHOU Juan, WAN Yu-jin, HUANG Li-xin
2004, 26(6): 571-573. doi: 10.11781/sysydz200406571
Abstract(690) PDF-CN(660)
Abstract:
Microscopic mechanism of the percolation of 2 phrases of gas and water in an etched porous net on a 2 dimensional glass board is investigated. Direct observation of horizontal pores shows that, driving of the 2 phrases of gas and water is quite different from imbibition. Although both of them are influenced by capillary force when gas and water flow slowly, the front of gas and water continuously flows and obviously skipps in the paths of big pores when they are driven. However, when they flow rapidly, an obvious phenomenon of viscous fingering could be found. The front of gas occurs as tree branches. The branching of it increases with the increasing velocity of gas and water. When water is imbibited slowly into pores along pore walls, it fills the small pore throats and fingers when driven by strong capillary force. It reaches every corner of the pore model along pore walls. The front of water propels evenly with the increasing velocity. Analysis of the micro-distribution of gas and water after experiment is helpful for improving oil and gas recovery efficiency.
APPLICATION OF HYDROCARBON GEOCHEMICAL EXPLORATION TECHNIQUE IN NATURAL GAS EXPLORATION
ZHAO Ke-bin, SUN Chang-qing
2004, 26(6): 574-579. doi: 10.11781/sysydz200406574
Abstract(902) PDF-CN(434)
Abstract:
Oil and gas geochemical exploration technique is a direct deploration technique based on the detection of the subtle matters dominated by hydrocarbon gases. With its unique advantages of being quick, effective and cheap, this technique can play a positive role in natural gas exploration. By means of study of the characteristics of the geochemical indicators and their anomaly distribution regularities over the typical known gas reservoirs, the most suitable geochemical indicators and methods for natural gas exploration were proposed. And by taking Xinchang Gasfield as an example, the authors explored the formation of (geochemical) anomaly provides additional supports for the effectiveness of the oil and gas geochemical exlporation technique in the expolration for natural gas.
INVESTIGATION ON THE POOL-FORMING TIME OF THE CHENGDAO OILFIELD IN THE BOHAIWAN BASIN USING THE HYDROCARBON GENERATION KINETICS METHOD
CHEN Yong-hong, LU Hong-you, ZENG Qing-hui, XIAO Xian-ming, TANG Yong-chun
2004, 26(6): 580-584. doi: 10.11781/sysydz200406580
Abstract(894) PDF-CN(454)
Abstract:
The Chengdao oilfield of the Bohaiwan Basin is characterised by complicated petroleum infilling history. Up to now, there still remain some problems to be solved. In this paper, the multi-cool traps GC, a patented instrument from the Californian Institute of Technology, is used, combined with related Kinetics software, to investigate hydrocarbon generation kinetics parameters of 2 typical source rocks from the southern part of Bozhong Depression. Based on this, petroleum generation history of source rocks from the Chengbei Depression and Sha'nan Depression is modeled with Kinetics software. The results have shown that, the Es3 source rocks from Chengbei Depression entered into oil window about 5 Ma ago, and the present conversion of hydrocarbons C13+ has reached 0.65. The Es3 source rocks from Sha'nan Depression have lower maturation level, with petroleum generation occurring 2 Ma ago, and the present C13+ conversion has reached 0.24. However, the Ed2 source rocks from these 2 depressions have not become mature. The Chengdao oilfield can be subdivided into 2 petroleum accumulation systems: the lower system of buried hill-lower Dongying Formation and the upper system of upper Dongying Formation-Minghuazhen Formation. Combined with petroleum geology and geochemistry of the petroleum accumulation systems, it is belived that, the lower accumulation system is mainly related to the earlier formed petroleum from the Es3 source rocks from Chengbei Depression, and petroleum in the upper accumulation system originated from the later stage petroleum generation of the Es3 source rocks from Chengbei Depression. The Es3 source rocks from Sha'nan Depression possibly have contribution to the lower accumulation system near slope area.
ORIGIN OF NATURAL GAS WITH ABNORMAL CARBON ISOTOPE COMPOSITION-A CASE STUDY OF THE EAST DEPRESSION, THE LIAOHE BASIN
MENG Wei-gong
2004, 26(6): 585-589. doi: 10.11781/sysydz200406585
Abstract(559) PDF-CN(473)
Abstract:
Carbon and hydrogen isotope composition of natural gas are effective geochemical measures to distinguish gas origin and type,provide insight of the correlation of different gas sources, and determine gas maturity. Study shows that, composition of carbon isotope of methane is mainly influenced by type of organic matters and thermal evolution. Composition of carbon isotope in heavy hydrocarbons, such as (ethane) and propane, is mainly determined by carbon isotope of organic matters of source rock. At the same time, it is apparently influenced by the degree of thermal evolution. Gas with abnormal carbon isotope composition has been found in the Liaohe Basin. This type of gas is distributed in the southern part of East Depression in the Liaohe Basin. The δ13C1 value of carbon isotope of methane is -44‰ to -40‰, the (δ13C2) value of ethane is -13‰ to -6.6‰, and the δ13C3 value of propane is -6.1‰ to +3.3‰. Ethane and propane of this type of gas are abnormally rich in heavy carbon isotope. This is the first time that this special type of gas is found. Geochemical data and geological setting analysis have proved that,this type of gas should fall into the category of mixed gas.
CARBON AND OXYGEN ISOTOPES OF CALCITE CEMENT IN THE LOWER PART OF THE SHA-1 FORMATION, THE DAGANG BEACH AREA
DONG Fu-xiang, LIU Li, MA Yan-ping
2004, 26(6): 590-593. doi: 10.11781/sysydz200406590
Abstract(661) PDF-CN(478)
Abstract:
Composition of carbon and oxygen isotopes of calcite cement from 12 samples in sandstone reservoirs of the Lower Part of Number 1 of Shahejie Formation, Dagang beach area, are analyzed. The δ13C va-lue of calcite cement varies from -9.58‰ to +3.61‰, and the average is 5.29‰; the δ18O value varies from -12.46‰ to +0.09‰, and the average is -6.28‰. Discussion of diagenetic fluid salinity, carbon source and formation cause suggest that, diagenetic fluid salinity of calcite cement in this area is high, and the calcite cement comes from intrastratal clastic carbonate or dissolution of calcite from adjacent layers. Carbon mainly originates from organic carbon.
PRODUCIBILITY EQUATIONS OF HORIZONTAL WELLS IN AREAL WELL SPACING SET UP BY THE EQUIVALENT FLOWING RESISTANCE METHOD
ZHOU De-hua, GE Jia-li
2004, 26(6): 594-596. doi: 10.11781/sysydz200406594
Abstract(806) PDF-CN(378)
Abstract:
Horizontal wells are more and more valuable beginning from adopted to oil and gas development. In fact, horizontal wells are used as producers as more as possible in offshore fields. The case was studied when horizontal and vertical wells were simultaneously deployed as producers and injectors respectively. It assumed that a central vertical well was surrounded by several horizontal wells. The producibility equations of horizontal wells in areal well spacing were presented by the equivalent flowing resistance method. It was efficient to predict that how much output should be designed for the development units of horizontal wells.

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