鄂尔多斯地台奥陶系岩溶储集层的成因及储集性能初析

PRELIMINARY ANALYSIS ON THE GENESIS OF ORDOVICIAN KARSTIFIED RESERVOIR AND ITS STORATIVITY IN ERDOS PLATFORM

鄂尔多斯地台奥陶系岩溶储集层主要发育在下马家沟组、上马家沟组及峰峰组粉—细晶白云岩、含膏云岩、盐溶角砾岩和颗粒灰岩中。主要储集空间类型为溶蚀孔隙和各种成因的裂隙。该区岩溶储集层有三种成因类型:第Ⅰ类为沉积成岩期形成的潮上萨勃哈层间岩溶储集层,第Ⅱ类为沉积成岩期形成的层间岩溶叠加加里东期风化、淋溶岩溶储集层;第Ⅲ类为深断裂岩溶储集层。前二类主要分布在地台中东部地区,具有好—较好的储集性能,后一种主要分布在地台西南缘,具有中等—较差的储集性能。

Ordovician karstified reservoirs are mainly located in poweraplite dolostone, gypsifer-ous dolostone, karst breccia and grainy limestone of Majiagou formation and Fengfeng formation in Erdos area. Main spatial types of reservoir are solution pore and fracture. There are three genetic types of reservoirs: The first type is strandflat reservoir which mainly occurs in central-eastern part of Erdos area. The second type of karstified reservoir is paleo-weathered leached rocks, including Caledonian which also mainly occurs in central-eastern part of Erdos area. The third type of karstified reservoir is deep faulted karstified one which is mostly developed along Yanshan or Himalaya fault zones. It mainly occurs in south-western margin of the platform. The practices of oil and gas exploration have proven that the oil reservoirs can be formed by the Mesozoic-Cenozoic hydrocarbon. It is important to study in the Ordovician carbonate rock reservoir for the hydrocarbon exploration in Erdos.