库车前陆冲断带深层大气区形成条件与地质特征

针对库车深层构造,开展"宽线+大组合"山地地震采集、高陡构造叠前深度偏移处理、深层构造建模等一系列地震勘探技术攻关,初步落实了盐下深层构造,发现并落实了一批大型构造圈闭。研究发现,库车前陆冲断带深层具有形成构造大气区的有利条件:大型叠瓦冲断构造为大油气区的形成奠定了良好的圈闭基础;优越的烃源条件与晚期强充注为大气区的形成提供了充足的烃源;深层发育大规模有效砂岩储集层,为大气区的形成提供了良好的储集空间;巨厚膏盐岩为深层大气区的形成提供了优越的盖层条件。盐下深层构造大气区油气地质特征主要表现为:油气分布受构造圈闭控制,以构造气藏为主;冲断带深层储集层物性总体较差,裂缝对油气富集高产有重要控制作用;油气分布具源-盖共控、叠置连片、整体含气的特点;储量规模较大,单井产能较高。

Formation and geological characteristics of deep giant gas provinces in the Kuqa foreland thrust belt, Tarim Basin, NW China

A series of seismic exploration technologies,such as the "wide line + big combination" mountainous seismic acquisition,highly steep structure pre-stack depth migration processing,and deep tectonic modeling,were used to explore Kuqa deep structures.Pre-salt deep structures were preliminarily confirmed and a group of large structural traps were found.The research shows that deep strata of the Kuqa foreland thrust belt are favorable for forming giant gas accumulations.Large-scale imbricated thrust structures prepare traps for large-scale oil and gas accumulation;excellent hydrocarbon source conditions and later intense charge of gas provide sufficient hydrocarbon sources;deep mass effective reservoir sandstone works as good reservoir space for giant gas accumulation;thick gypsum serves as good cap.The geological characteristics of giant gas accumulations in deep pre-salt structures are as follows: Hydrocarbon distribution is controlled by structural traps and structural gas reservoirs are dominant;reservoir properties of deep thrust belt are generally poor,with fractures being the important controlling factor for hydrocarbon enrichment;oil and gas distribution is characterized by joint control of source and cap,stacking of multi-layer beds,and overall beds containing gas.Reserves are large,and single well productivity is high.