霍玛吐背斜带构造演化特征及对油气藏的控制

Tectonic Evolution and Controls on Hydrocarbon Accumulation in Huoerguosi-Manasi-Tugulu Anticline Belt in Southern Junggar Basin

霍玛吐背斜带位于准噶尔盆地南缘山前冲断带中段,由于中深层地震资料品质差,长期以来,对这一背斜构造带的演化特征及其与油气成藏关系一直未能查清。结合该区2011—2013年地震攻关宽线成果,以断层相关褶皱理论为基础,利用生长地层分析及构造几何正演模拟等技术,对背斜的构造样式、构造演化及油气成藏特征进行了细致分析。研究认为,霍玛吐构造带(霍尔果斯背斜、玛纳斯背斜和吐谷鲁背斜)纵向上为深部断层转折褶皱与浅部断层传播褶皱组成的复合型背斜,平面上,深、浅层构造都呈"品"字形排列,横向上呈现此消彼长的渐变构造过渡关系;霍玛吐背斜带在喜马拉雅运动期经历了早期深部断层转折褶皱发育期、中部反向断裂发育期和晚期浅层霍玛吐断裂冲断改造期三个演化阶段;其油气主要存在两期充注,先油后油气,喜马拉雅运动期三期构造演化与两期油气充注匹配,且构造演化特征控制了各构造的油气成藏过程。综合分析认为,霍玛吐构造带反向断裂下盘中深层构造高部位的白垩系和中上侏罗统优质储集层是准噶尔盆地南缘有利的油气勘探领域。

Huoerguosi-Manasi-Tugulu （Huo-Ma-Tu） anticline belt is located in the middle part of the piedmont thrust zone of the southern margin of Junggar basin.Because the seismic data from the mid-deep strata area poor in quality,the anticline structural evolution characteristics and its relationship with hydrocarbon accumulation are unclear for a long time.This paper combines with the seismic wide line research achievements in the last two years,and analyzes particularly the structural style,tectonic evolution and hydrocarbon accumulation characteristics of Huo-Ma-Tu anticline using fault-related folding theory,growth strata analysis and structure geometry forward modeling technology,etc.The result shows that Huo-Ma-Tu structural belt is a complex anticline composed of deep fault bend folds and the overlying shallow fault propagation folds on vertical zonation.The deep and shallow structures are on stagger arrangement in the plane and present on the lateral shift of gradient structure transition relationship.Huo-Ma-Tu anticline develops three periods of Himalayan tectonic evolution sequences：deep fault bend folds development period,middle back-thrust faults development period and shallow Huo-Ma-Tu fault thrust transformation period.And there exist two hydrocarbon-charging times in it：oil charging for the first time,oil and gas charging for the second time.The three periods of Himalayan tectonic evolutions well matched with the two hydrocarbon-charging times,and the tectonic evolution characteristics of the anticline controlled the whole process of oil and gas accumulation.The comprehensive analysis suggests that the high-quality reservoirs of Cretaceous and Middle-Upper Jurassic in mid-deep structure highs in the back-thrust faulting footwall are also favorable oil and gas exploration domains in the southern margin of Junggar basin.