Factors Affecting on Dissolution Porosity in Deep Burial Clastic Reservoirs-Examples from Jizhong Depression and Tarim Basin
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摘要: 在一个含油气盆地内,随着勘探程度的提高,深层作为新的油气勘探领域越来越引起人们的关注。深层碎屑岩储层储集空间类型以次生溶蚀孔为主,被溶解物质往往是碎屑岩原始沉积的骨架颗粒和早期化学胶结物。塔里木三叠系砂（砾）岩以岩屑砂岩为主,其中碳酸盐胶结物含量为5～35%;冀中下第三系砂岩以长石砂岩为主,并含有丰富的碳酸盐胶结物（3～35%）;这些物质为晚期溶解形成次生溶蚀孔隙提供了丰富的物质基础。冀中下第三系深层碎屑岩当埋深大于3500m时,实测岩心孔隙度最大值小于20%;渗透率最大值小于100×10-3μm2;大多数砂层的孔隙度小于10%;渗透率小于10×10-3μm2;单井日产液量不足100吨。而塔里木盆地三叠系碎屑岩储层,在埋深5000m时仍具有孔隙度最高值大于20%、渗透率最高值大于1000×10-3μm2的储集条件;单井产油量达到日喷油大于500吨,天然气大于1万立方米。本文通过对这两个地区深层碎屑岩储集条件分析认为两地古今地温场的差异是影响深部碎屑岩成岩作用的主要因素;多套烃源岩层系热演化时间跨度的差异直接影响了深部储层储集能力。Abstract: Secondary porosity caused by dissolution of primary skeleton grains and chemical cements is the most important petroleumstorage spaces in deep burial elastic reservoirs. Lithic arkose is the main component of Triassic reservoir sandstones in the Tarimbasin ; carbonate cement in the reservoir ranges from 5 % to 35 %，and in the Tertiary of the Jizhong Depression the common reser-voir rock is arkose, of which carbonate cement is between 3 % and 35 %.The feldspathic grains and carbonate cement provide 6a-sic materials for the formation of solution porosity. Cores taken from below 3500m in Jizhong Depression show the maximumporosity < 20 % and maximum permeability<100 x 10-3pm2. Most of the samples have porosity<10 % and permeability<10x10-3pm2;In the Tarim basin the Triassic sandstone reservoirs buried deeper than 5000m still have maximum porosity > 20 %and permeability 1000 x 10-3pm2. Production shows that when elastic reservoir buried deeper than 3500m in Jizhong Depressionthe fluid production is always less than 1002/d; while in the Tarim Basin when buried below 5000m, Tertiary elastic reservoirs stillhave an oil production of 500t/d and gas 100000m3/d. This paper compares the deep burial elastic reservoirs in the Tertiary of theJizhong Depression with the Triassic of Tarim Basin and discusses the factors affecting the porosity evolution in deep burial situa-lion. Geotemperature and multiple hydrocarbon sources are the main factors that bring about the difference of reservoir storage ca-pacify in deep burial elastic reservoirs in the Jizhong Depression and the Tarim Basin.
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Key words:
- clastic reservoir /
- diagenesis /
- secondary porosity /
- Jizhong depression /
- Tarim basin
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[1] Surdam R. C.，Crossey L.J.，Hagen E. S. et al.，Organic-inor-ganic Interaction and Sandstone Diagenesis, AAPG Bulletin,1989, 73(1):1~23. [2] John M.，Hunt, Petroleum Geochemistry and Geology, W . H.Freeman and Company, 1979. [3] Bjorlykke K. and Egeberg P. K.，Quartz Cementation in Sedi-mentary Basins, AAPG Bulletin, 1993, 77(9) :1538~1548. [4] 童晓光等.塔里木盆地油气勘探论文集.乌鲁木齐:新疆科技卫生出版社。1992.321~363. -
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