摘要:
奥陶系碳酸盐岩古风化壳经历了漫长的沉积间断,期间遭受了长期的风化剥蚀与淋滤溶蚀作用,岩溶十分发育。根据不同的岩溶形态及构造成因可分为溶洞、溶缝、构造缝、溶蚀孔、压溶缝及缝合线。洞穴型岩溶储层以其空间规模在油气勘探开发中占据重要地位。其在地质、钻井、录井及测井上均具有一定的响应特征。结合现代岩溶理论,洞穴型岩溶储层在距古风化壳面150 m深度范围内均有可能发育,且充填程度与连通性的好坏决定了油气的储集与运移特征。结合具体井点的测井曲线分析了砂泥质全充填溶洞和未充填溶洞的测井响应特征。
Abstract:
Suffered from a long period of weathering, erosion and leaching, karst was widely developed in the Ordovician carbonate rocks in North China. Depending on the morphology and tectonic origin of karst, caves can be divided into dissolved joints, construction joints, corrosion holes, pressure solution seams and the suture lines.The Karst cave, as a type of reservoir, occupies an important position in the oil and gas exploration and development due to its spatial scale. Using some characteristics mentioned in this paper, karst caves are possible to be identified from geological, drilling, and logging records. In accordance with the modern theory of karst formation, caves are developed in a zone 150 meter below the palaeo-weathering crust. The quality of carbonate reservoirs and the migration of oil and gas depend upon the filling degree and connectivity of the caves. Characteristics of logging response to mud-filled and unfilled caves summarized from specific wells are presented in this paper.
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