塔中Ⅰ号坡折带奥陶系礁滩体油气藏的成藏特点

Characteristics of the Ordovician Reef-Shoal Reservoir in Tazhong No.1 Slope-Break Zone,Tarim Basin

塔里木盆地塔中Ⅰ号坡折带奥陶系油气田是我国第一个以礁滩体为储集体的大油气田。该油气田不同井的测试产量和气油比差异较大,油气性质复杂,既有正常油也有凝析油,天然气中普遍含有H2S,非烃气含量在不同井区变化大。油气藏研究表明,北部为富气、南部为富油,不同性质的油和气分段性分布,油气主要来源于寒武系,喜马拉雅运动期的大规模气侵和良好的保存条件是形成奥陶系大油气田的主要原因。

The Ordovician oil-gas field in Tazhong No.1 slope-break zone in Tarim basin is the first large-sized field where the reservoir is dominated by reef and shoal complex facies. This field is characterized by big differences of testing production and gas/oil ratio in different wells, complex oil and gas properties, having both normal oil and gas condensate, generally containing H2S in natural gas, and varied contents of non-hydrocarbon gas in different well blocks. The study shows that the gas is rich in the northern part and the oil is rich in the southern part; such distinctive oil and gas in sectional distribution mainly originated in the Cambrian. It is concluded that Himalayan movement is the main reason for forming this large-sized field of Ordovician due to cosmically gas invasion and better preserved conditions in this area.