塔里木盆地库车坳陷克拉苏和东秋断层上盘勘探突破方向

塔里木盆地库车坳陷前陆冲断带成藏条件优越，特别是克拉苏构造带和东秋构造带，发现了克深大气藏群、克拉2大气藏和中秋1气藏，形成了超万亿立方米大气区。但目前发现的气藏平面上主要分布在克拉苏断层和东秋断层下盘，断层上盘仅仅发现了克拉2大气藏，纵向上主要赋存于白垩系巴什基奇克组。基于上述油气分布现状分析，认为克拉苏断层下盘之所以形成连片分布的大气藏群，主要是一系列近东西走向的逆冲断层形成了成排、成带的大型背斜和断背斜构造圈闭，控圈断层下通烃源岩，上达膏岩盐盖层而未断穿，既是油气运聚通道而又没有破坏圈闭的封闭性，这种成藏要素的绝佳匹配造就了克拉苏断层下盘连片大气藏群的形成；而由于克拉苏断层和东秋断层断穿膏盐岩甚至断达地表，造成断层上盘圈闭封闭性变差，致使具有相同储盖组合的白垩系巴什基奇克组圈闭未能成藏，但在断层上盘由于顶冲构造形成了独特的克拉2“盐包圈”圈闭，发育了独一无二的克拉2大气藏。其次，通过分析克拉苏逆冲断层和东秋逆冲断层对成藏的控制，认为断层对纵向上不同层系及不同类型储盖组合的成藏影响是不同的。从油气复式聚集理论出发，考虑克拉苏构造带和东秋构造带丰富的剩余油气资源，以及断层上盘、下盘勘探不均衡的现状，通过解剖吐格尔明逆冲断层上盘侏罗系成藏模式，以及克拉苏断层上盘和东秋断层上盘古近系成藏模式，提出克拉苏断层和东秋断层上盘尚有巨大的勘探潜力，侏罗系和古近系是断层上盘下步重大的突破方向。

Exploration directions on the Kelasu and East-Qiulitag fault hanging walls,Kuqa Depression,Tarim Basin

The foreland thrust belts come in favorable accumulation conditions in the Kuqa Depression,Tarim Basin.Of the belts,the Kelasu and East Qiulitag belts,in particular,contain a giant gas field of over trillion-cubic-meter reserve consisting of Keshen,Kela 2 and Zhongqiu 1 gas reservoirs.Horizontally,most of the reservoirs concentrate on the footwalls of Kelasu and East-Qiulitag Faults,only Kela 2 is on the hanging wall.Vertically,the reservoirs mainly occur in the Cretaceous Bashijiqike Formation.Analyses show that the somehow continuous gas reservoir on the footwall of Kelasu Fault were trapped by rows or belts of large-scale anticlines and faulted anticlines formed by a series of nearly EW-trending thrust faults.The faults that get connected to hydrocarbon source rocks downward and to gypsum-salt cap rocks upward without cutting them through,serve as effective migration channels while keeping the integrity of the trap untouched,thus making a perfect pooling combination.While on the hanging walls,gas traps with similar condition were mostly destroyed by the Kelasu and East-Quilitag Faults cutting through the gypsum-salt cap rocks,leaving only the Kela 2 reservoir preserved by salt on the top-up structure.Meanwhile,analysis of the Kelasu and East-Qiulitag Faults’control on the reservoirs shows various impact upon different reservoir-cap assemblages and strata in a vertical direction.In all,the study dissected the accumulation model on the hanging walls of the Kelasu and East-Qiulitag Faults through composite hydrocarbon accumulation theory while considering the abundant surplus resources and the exploration imbalance of the hanging walls and the foot walls,and suggested that the hanging walls of the Kelasu and East-Qiulitag Faults have great exploration potential and the Jurassic and Paleogene strata are targets of future exploration on the foot walls of the faults.