塔里木盆地异常高压气藏的主要地质特征和成藏模式

Main geological features and accumulation models of abnormally high-pressured gas reservoirs in Tarim Basin

在全面论述塔里木盆地异常高压气藏分布的基础上,重点剖析了南天山和西昆仑山的山前坳陷的区域演化、异常高压成因、储气构造形成和成藏期,进而提出其成藏模式,探讨异常高压气藏形成的关键和勘探靶区。库车坳陷除依南2气藏为自源型外,其它5个气藏均属晚期充注型;主成藏期是中新世晚期—上新世早期,背斜发育受一组后展式扩展的逆冲断层控制,更新世以来天然气向原储气构造内充注,异常高压是自源型高压和传导型高压的叠加。叶城凹陷柯克亚背斜深部的古近系在中新世成藏,上新世-早更新世随地层褶皱发生调整,属晚期调整的气藏;浅部的中新统气藏则是晚期充注型,除气源岩供气外还有深部的古近系气藏为之供气,应属晚期次生成藏。

The abnormally high-pressured gas reservoirs were well developed in the Tarim Basin. It was discussed in this paper the abnormally high pressures in foreland depressions, including regional evolution, contributing factors, formation of gas-bearing structures, accumulation mechanisms and periods, and then presenting accumulation models for the Kuqa Depression and the Yecheng Sag respectively. The keys for abnormally high-pressured gas reservoirs and the exploration targets were studied. There were 6 abnormally high-pressured gas reservoirs in Kuqa area, 5 of which were late-charged while only the Yinan2 gas reservoir was self-sourced. The main accumulation period was from the Late Miocene to the Early Plioeene. Anticlines were controlled by a group of overstep reverse faults. Natural gas charged into gas-bearing structures directionally due to the structural compression since Pleistocene. Self-sourced high pressure and transitional high pressure together formed abnormally high pressure. The deep Paleogene gas reservoir in the Kekeya anticline of Yecheng Sag, namely, the Kalata＇ er gas reservoir, ac- cumulated in Miocene and adjusted with stratigraphie folding in Pliocene-Early Pleistocene, which was an abnormally high-pressured gas reservoir of late-adjustment type. The shallow Miocene gas reservoir in the Kekeya anti- cline was late-charged, with both the source beds （the Carbono-Permian and Jurassic） and the deep Paleogene gas reservoir supporting gases, which should be a later secondary-generated accumulation.