塔河奥陶系碳酸盐岩油藏缝洞系统发育模式与分布规律

塔河奥陶系碳酸盐岩缝洞型油藏是以缝洞为主要储集空间的特殊型油藏。区域构造演化与古岩溶发育关系密切，塔河地区奥陶系碳酸盐岩经历了加里东中期及海西早期岩溶作用，海西早期裸露风化壳岩溶作用是塔河岩溶储集体发育的主要因素。塔里木盆地北缘一间房、硫磺沟、三道班和五道班等地区奥陶系古岩溶露头地质调查及塔河油田储集体发育特征揭示该区奥陶系碳酸盐岩存在地下河系统型、岩溶洞穴型和溶蚀孔缝型3大类型的缝洞系统发育模式。地下河系统和岩溶洞穴是最主要的储集体类型。断裂带附近是缝洞系统发育的密集带；古地貌控制了缝洞系统的平面分布，岩溶台地内的峰丛洼地区溶洞最发育，其次以岩溶缓坡内的丘峰洼地区和丘丛垄脊槽谷区古岩溶缝洞系统发育程度高；垂向上溶洞发育具有明显分带性，表层岩溶带是最重要的岩溶发育段。

Developmental pattern and distribution rule of the fracture-cavity system of Ordovician carbonate reservoirs in the Tahe Oilfield

Ordovician carbonate fracture-cavity reservoirs in the Tahe Oilfield are a special type of reservoirs, in which fractures and cavities constitute the main reservoir space. In the Tahe area, the development of ancient karst is closely related with the regional tectonic evolution because Ordovician carbonate reservoirs in the Tahe Oilfield experienced karstification in the middle Caledonian and early Hercynian, and the karstification of the long-term exposed weathering crust during the early Hercynian played a major role in controlling the development of these karst reservoirs. Based on the geological survey of palaeokarst outcrops of the Yijianfang, Liuhuanggou, Sandaoban and Wudaoban regions in the northern margin of the Tarim Basin, developmental characteristics of reservoirs in the Tahe Oilfield revealed that there were three developmental patterns of the fracture-cavity system in Ordovician carbonate reservoirs: i.e. underground river system, karst caves, and corroded pores and fissures, of which the former two were the most dominant types for the reservoirs. The fracture-cavity system developed well in the vicinity of fault belts, and the horizontal distribution of the fracture-cavity system was controlled by palaeo-geomorphology. For instance, karst caves were extremely well-developed in peak-cluster of a karst platform, and then in knob-and-kettle topography on gentle karst slopes and in rugged country of valleys. Vertically, the development of karst cavities was apparently of zoning and superficial karst belts were the most important segment for karst development.