塔里木盆地库车坳陷克拉苏构造带古近系膏盐岩盖层演化与圈闭有效性

膏盐岩层是含油气盆地良好的区域盖层,但不是完美的盖层。研究表明,膏盐岩具有"低温脆变、高温塑变"特征,构造挤压背景下膏盐岩盖层的封闭性随埋深而演化,大于3 000~3 200 m的埋藏深度是克拉苏构造带膏盐岩盖层封闭的关键。克拉苏构造带盐下圈闭成藏有效性因盖层封闭性演化不同而异,克拉苏区带盖层封闭的关键时间为库车中晚期,以勘探盖层埋深超过3 200 m的完整背斜圈闭为主;克深区带盖层封闭的关键时间为库车早中期,在断层侧向封堵时盐下断块、断背斜等圈闭均可聚集油气。研究成果与勘探现状吻合,并有利于提高勘探成功率。

Evolution of Paleogene saline deposits and effectiveness of traps in Kelasu tectonic zone,Kuqa Depression,Tarim Basin

Saline deposits are good regional cap rocks in petroliferous basins, yet not perfect. Research shows that saline deposits are characterized by "embitterment at low temperature and plastic deformation at high temperature". The sealing capacity of saline deposits changes with burial depth, and the depth from 3 000 to 3 200 m is critical to the capping effectiveness of saline deposits in the Kelasu tectonic zone. The effectiveness of subsalt trap accumulations is influenced by the evolution of saline deposits. The key time for the closing of cap rocks in the anti-cline zone of Kesalu is the middle and late Kuqa periods, and the main exploration targets are the complete anticline traps buried over 3 200 m deep. In the deep zone of Kelasu, the key time for the closing of cap rocks is the early and middle Kuqa periods, and petroleum may be trapped in subsalt blocks and broken anticlines when faults are laterally sealed. Research fits the status of exploration, and helps to improve exploration success rate.