Abstract: The largest Ordovician reef-type oil and gas reservoir discovered in China is distributed along the Upper Ordovician carbonate platform margin in the northern of central uplift of Tarim Basin.It is an unconventional hydrocarbon reservoir with complicated oil-gas-water distribution and without obvious edge water and bottom water.The analyses on forming condition and enrichment law of the reservoir showed that a large rimed carbonate platform margin system was formed,and multi-phases depositions of reefs,banks and limemud mounds were developed in the early stage of the Late Ordovician along the northern margin of central uplift.The vertically superimposed and laterally connected reef-type reservoir was distributed widely along the platform margin of Tazhong No.1 structural belt and has many kinds of secondary corrosion voids characterized by low porosity and low permeability.Three major stages of hydrocarbon activities were accountable for the abundant hydrocarbon accumulation.The low-abundance reef-bank type lithologic reservoirs were distributed along the margin tectonic zone.The carbonate platform margin controlled the hydrocarbon migration and accumulation,and a large hydrocarbon-enriched belt was formed.The oil-gas enrichment was mainly controlled by reservoirs.The difference of oil and gas occurrence was caused by multi-stage hydrocarbon accumulation and heterogeneity of reservoirs.

Key words: Tarim Basin, Ordovician, carbonate rock, platform margin, oil-gas reservoir, forming condition, oil-gas enrichment law

摘要： 在塔里木盆地塔中地区发现了中国最大的奥陶系生物礁型碳酸盐岩油气藏,油气沿塔中隆起北部上奥陶统碳酸盐岩台缘相带展布,为无明显边底水、油气水分布复杂的非常规油气藏。对油气成藏条件与油气富集规律研究表明,塔中上奥陶统良里塔格组发育大型镶边台地边缘礁滩相沉积系统;礁滩体储层纵向叠置、横向连片,沿塔中Ⅰ号构造带台地边缘广泛分布,并以次生溶蚀孔洞形成的低孔隙、低渗透储层为主;三期油气充注与成藏形成了巨大的资源潜力,沿台缘带形成大面积、低丰度准层状礁滩型岩性油气藏。大型台缘相带控制了塔中Ⅰ号构造带的油气运聚成藏,储层是油气富集的主控因素,多期油气成藏与储层非均质性造成了油气赋存的差异性。

关键词: 塔里木盆地, 奥陶系, 碳酸盐岩, 台缘相带, 油气藏, 形成条件, 油气富集规律