Structural evolution and distribution of paleokarst reservoirs in the O rdos Basin

doi:10.11743/ogg20100513

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Structural evolution and distribution of paleokarst reservoirs in the O rdos Basin
Vol. 31, Issue 5, Pages: 640-647(2010)
Online First：28 October 2010，

Published：2010
DOI： 10.11743/ogg20100513
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DOI：

Structural evolution and distribution of paleokarst reservoirs in the O rdos Basin[J]. 2010, 31(5): 640-647. DOI： 10.11743/ogg20100513.

摘要

利用地层残余厚度法，恢复了鄂尔多斯盆地不同时期的古构造面貌，结合奥陶系岩溶储层的分布特征，分析了古构造演化过程对岩溶储层发育的影响。鄂尔多斯盆地奥陶系沉积时期为中部高、东西低，西陡东缓的古构造面貌，东部缓坡带发育含膏白云岩沉积相带，为古岩溶储层的发育奠定了物质基础。自奥陶系沉积后，缺失了大约1.3×10 12 a的沉积，古构造面貌继承发育，中部古隆起东斜坡带在古地貌上隶属于岩溶斜坡区，水流集中，径流活跃，为风化壳岩溶储层的发育创造了有利条件。自石炭纪本溪期重新接受沉积后，至早、中三叠世奥陶系顶部剥蚀面始终保持了中部高、东西低的古构造面貌，古隆起带是地下活动性流体运移的有利指向区，隆起斜坡带在早期风化壳岩溶的基础上，更有利于埋藏期岩溶的形成。

Abstract

Using residual thickness method，paleoˉtectonic features during different periods are recovered in Ordos Basin.Taking karst reservoirs in the Ordovician as an example，this paper also discusses the influence of paleoˉtectonic evolutionary process on the development of karst reservoirs.In the Ordovician，the paleotectonics ofOrdos Basin features in one high between an eastern lowwith gentle slope and awestern lowwith steep slope.Dolom itewith gypsum deposited on the eastern gentle slope，and provided amaterial basis for the developmentof paleokarst reservoirs.After the Ordovician，there was a hiatus about1.3×10 12 years and the previous tectonics was inherited.From a paleogeomorphic pointofview，the eastern slope of the central paleohigh belongs to a karst slope where concentrated water flow and active throughflow provided favorable conditions for the development of karst reservoirs ofweathering crust type.From the Carboniferous Benxi period when deposition renewed to the Early-Middle Triassic，the erosion surface on top of the Ordovician keptprevious paleotectonic features.The paleohigh is believed to be favorable destinations for subsurface active fluids.The slope zones，which experienced karsitification ofweathering crusts earlier，are favorable for the development of burial karsitification.