【摘要】 塔中地区北部奥陶系发育碳酸盐台地—陆棚边缘高能滩相,仅上奥陶统良里塔格组滩体就厚约100?300m,有效储层厚约50?100m,滩体颗粒灰岩构成典型的非均质碳酸盐岩古岩溶岩性储集体圈闭,圈闭面积可达1000?2000km2,迄今钻遇的12口井有9口井获得工业油气流,初步预计储量可达(5?10)×108t油当量,应该是特大型整装原生岩性油气藏,可能成为塔里木盆地尚未探明的最大整装油气田。该油气藏成藏条件优越,是满加尔凹陷油气源区多期油气特别是晚海西期油气首先充注的圈闭;多期岩溶作用造就了较好的滩体储集空间,颗粒灰岩储层的非均质性既为油气勘探带来了难度,也为该岩性圈闭侧向封堵的形成创造了条件;埋藏深度适中及后期构造改造微弱有利于滩体原生油气藏的保存;滩体地震响应特征易于识别追踪,总体表现为低频空白弱反射或者是低频强—弱相间反射。初步研究认为,塔里木盆地奥陶系碳酸盐岩具备相似成藏条件即形成大中型原生岩性油气藏的地区还有阿瓦提凹陷南部—巴楚凸起北缘及塔北隆起南斜坡—北部坳陷北缘,塔里木盆地奥陶系原生岩性油气藏具备十分广阔的勘探前景,是发现大中型油气藏的现实领域。更多还原

【Abstract】 Ordovician System in the northern part of Tazhong region has development of high-energy shoal facies of carbonate platform-shelf margin. Only the shoal body of Upper Ordovician Lianglitage Formation has a thickness of 100~300 meters and the effective thickness of the reservoirs is 50~100 meters. Grain carbonate rock of shoal body shaped the typical heterogeneous carbonate rock palaeokarst lithologic trap with an area of 1000~2000 square kilometers. Of the 12 wells drilled at the present time, nine ones have acquired commercial oil and gas ?ow. Based on the preliminary estimation, the reserves can reach (5~10) ×108t oil equivalent. It is supposed to be a giant original lithologic oil and gas reservoir and possibly becomes the largest oil and gas ?eld in Tarim Basin that has not yet been proven. With the advantageous conditions for migration and accumulation, this oil and gas reservoir was the ?rst trap in Manjiaer Depression sourcing region injected with oil and gas during multiple stages, Late Hercynian Period in particular. The multi- stage karsti?cation created desirable shoal body reservoir space while the heterogeneity of grain carbonate rock reservoir either caused dif?culty for oil and gas exploration or created the conditions for lateral sealing of the lithologic trap. The appropriate buried depth and the later weak structural reform are favorable for storage of the shoal body original oil and gas reservoir. The seismic response characteristics of shoal body are easily identi?ed and traced. It takes the form of low-frequency blank weak re?ection or low-frequency strong-weak alternating refection. Based on the preliminary study, Ordovician carbonate rock of Tarim Basin has the conditions for migration and accumulation. The areas for forming large and medium-size original lithologic oil and gas reservoirs also include the southern part ofAwati Depression, the northern periphery of Bachu Uplift and the southern slope of Tazhong Uplift as well as the northern periphery of North Depression. Ordovician original lithologic oil and gas reservoirs have an extremely broad prospect for exploration and are regarded as the ?eld to discover large and medium-size and oil and gas reservoirs.更多还原