| 摘要: |
| 塔河油田奥陶系发育了典型的岩溶储层,大于70％的缝洞空间在岩溶发育期及岩溶埋藏期被沉积充填物、垮塌充填物和化学充填物所充填,造成岩溶储层极度非均质性。通过岩心观察、测井资料解释、岩矿和地球化学分析,建立缝洞充填物识别方法。结果表明:沉积砂泥岩占总缝洞充填物的60％以上,地表河和地下河沉积特征明显,其中沉积砂岩是重要的油气储层;两种河流均发育心滩和河漫滩,前者砂岩颗粒较粗,常为含砾的粗—中砂岩,地化分析表明为氧化环境产物;后者以细砂岩为主,石英含量比前者高40％,为弱氧化—弱还原水体沉积;地表河沉积砂泥岩常与坡积物互层,地下河沉积砂岩与垮塌角砾岩或潜流带细粒沉积物呈互层;前者受压实作用明显,储集物性差;后者压实作用很弱,物性好、含油性好;地下河沉积砂岩是径流岩溶带重要的储层,对于深入认识塔河油田岩溶储层地质特征具有重要意义。 |
| 关键词: 岩溶型储层 地表河 地下河 沉积砂岩 储集物性 塔河油田 |
| DOI：10.3969/j.issn.1673-5005.2015.06.001 |
| 分类号::TE 121.31 |
| 基金项目:国家重点基础研究发展计划(2011CB201001) |
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| Sedimentary and geochemical characteristics of sandstones and mudstones deposited in surface rivers and subsurface rivers in Ordovician karsted carbonates, Tahe Oilfield |
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JIN Qiang1, KANG Xun1, RONG Yuanshuai2, TIAN Fei1
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(1.School of Geosciences in China University of Petroleum, Qingdao 266580, China;2.Xibei Bureau of Petroleum Geology, SINOPEC, Urumqi 830011, China)
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| Abstract: |
| Ordovician carbonates in Tahe Oilfield were typical karst reservoirs in the world. Fracture-caves were general storage spaces for oil and gas in the karst carbonates, but the spaces more than 70％ had been filled with river deposits, collapsed breccias and chemical materials, which resulted in heavy heterogeneity in the karst reservoirs. By investigating drilling cores and well-logging and by using rock-mineral and geochemical measurements on some core samples, the authors found that sedimentary sands and muds were over 60％ in the total fracture-cave fillings; the sediments were obviously in sequences of surface rivers and subsurface rivers which were developed in the carbonates during the karst on the Tabei uprise; and the sandstones deposited in the subsurface rivers were important reservoirs in caves of runoff karst zone. Channel bars and river banks are identified from the sediments deposited in either surface rivers or subsurface rivers. The sandstones deposited in surface rivers are usually in coarse-to-medium grain size, but in the subsurface rivers they are characterized as fine-sands or silt-sands. Composition and texture maturities of the subsurface-river sandstones are much higher than those of surface-river sandstones:the quarts contents in the subsurface-river sandstones is 40％ higher than those in surface-river sandstones. The surface-river sandstones were deposited in open oxidative water, and interbedded with slope wash breccias; in comparison the subsurface-river sandstones were deposited in weak-oxidative to weak reductive waters, and interbedded with collapsed breccias, which were in good physical condition for oil and gas. The subsurface-river sandstones are good reservoirs in runoff karst zones in Tahe Oilfield. Oil production from the sandstones is expected to increase the oil-recovery in the karst reservoirs. |
| Key words: karsted carbonate reservoir surface-river subsurface-river sedimentary sandstone physical property Tahe Oilfield |
