南华北地区奥陶系古喀斯特特征及其储层前景

摘要

南华北地区奥陶系古喀斯特广泛发育,为油气成藏提供了有利条件.通过野外露头剖面观测、钻井岩心观察,奥陶系古喀斯特主要发育于下奥陶统亮甲山组和奥陶系顶部,表现为不整合面(风化壳)残积物、喀斯特角砾、溶蚀孔洞缝等特征.将奥陶系古喀斯特划分为同生期、表生期和埋藏期喀斯特三类,同时讨论了影响和控制奥陶系古喀斯特发育的因素,其中构造、岩性、气候和古地貌为主要因素.研究区受构造隆升控制的表生期喀斯特和同生期喀斯特在横向上分布连续,有利于喀斯特储层发育;另外,奥陶系埋藏期喀斯特广泛发育,也有可能形成有利储层.%The palaeokarst growth of Ordovician in the south of North China is beneficial to the oil and gas reservoirs. Through studying field sections, drilling cores and logging data, the authors found that the Ordovician palaeokarst has mainly grown in the Lower Ordovician Liangjiashan Formation and the top of Ordovician and has the characteristics of unconformity residuals (crust of weathering), the karst breccia, the corrosion hole seam, and so on. According to analysis of the stratum isopach map of Pre-Carboniferous and Pre-Majiagou stage, the authors drew two maps about the Pre-Carboniferous karst landform and Pre-Majiagou stage karst landform. The palaeo-landform unit was divided into the karst high ground, pitch, and depression. The Ordovician palaeokarst is divided into syngenesis solution, epidiagenesis solution, and burial solution. The lithological character, tectonic movement and climate are the primary factors to control the Ordovician palaeokarst. The syngenesis solution and epidiagenesis solution controlled by the tectonic uplift are distributed continually and conducible to the development of karst reservoirs. In addition, the burial solution also quite grow, and can be beneficial to form the reservoirs.