摘要:
风化壳岩溶是鄂尔多斯盆地奥陶系古岩溶演化经历的主要阶段。通过对盆地中东部的钻井岩心、薄片观察及测井资料进行分析,结合水动力特征的差异,以SH15井为例对风化壳岩溶带进行了划分,在垂向上自上而下分为垂直渗滤带、水平潜流带和深部缓流带,分析了古风化壳岩溶作用,总结了风化壳岩溶的发育模式。并结合岩相古地理、古地貌等特征,分析了古岩溶储层特征及其控制因素,揭示了风化壳岩溶和天然气富集的关系,为鄂尔多斯盆地奥陶系天然气勘探提供依据。
Abstract:
The formation of karst weathering crust is the major phase of the palaeo-karst evolution in the Ordovician limestone in the Ordos Basin. Based on the study of cores, thin sections and well logs from the central and eastern parts of the basin, combined with its specific hydrodynamic characteristics, this article takes the Well SH15 as an example to study the process of karstification. Three zones of weathering crust karst were recognized. They are, from the top to the bottom, vertical vadose zone, horizontal subsurface flow zone and bedrock subcritical flow zone. The process of palaeo-weathering crust karstification was discussed, and a model was established in this paper. The Ordovincian karst limestone is an important reservoir in the region. The characteristics of palaeokarst reservoirs and their governing factors are carefully studied based upon the data of lithofacies, palaeogeography, palaeogeomorphology and so on. Results show that the enrichment of natural gas is related to the development of weathering crust karst in this region. The conclusion is helpful to gas exploration in the Ordos Basin.
下载: