金马—鸭子河地区构造演化特征分析及与油气藏关系

Structural evolution characteristics and hydrocarbon accumulation of Jinma-Yazihe area

金马—鸭子河地区位于龙门山褶皱冲断带与四川台坳(盆地)的交界处,依据三维地震资料对断裂特征及构造演化过程进行分析可知,关口断裂下盘发育的白鹿场断裂可视作其先存断裂,形成的构造楔造成关口断裂下盘地层局部增厚。关口断裂南东方向收缩程度渐小,总体表现出双滑脱层控制的分层滑脱断层垂向叠加构造组合。彭县断裂为多条断裂构成的断裂带,中段断距较大,可以作为局部构造应力转换或集中的指示。金马—鸭子河地区主要断裂活动起始于印支早期,在印支运动晚期持续变形,强烈活动于燕山期,关口断裂、彭县断裂于燕山期发生强烈逆冲,与喜马拉雅期至新构造期持续变形,发生走滑并影响至地表。构造活动与油气成藏具有密切联系,对于构造圈闭形成、储层改造、油气运移和聚集均有贡献。

Jinma-Yazihe area is located at the junction of Longmenshan fold-thrust belt and Sichuan basin.Based on the 3D seismic data,the characteristics of faults and the process of tectonic evolution are analyzed.The Bailuchang fault developed in the lower wall of Guankou fault can be regarded as its pre-existing fault,and the formed structural wedge causes local thickening of the lower wall.The shrinkage degree of the Guankou fault in the southeast direction is becoming smaller and smaller,which generally shows the vertical superimposed structural combination of stratified slip faults controlled by double slip layers.Pengxian fault is composed of several faults with a large fault distance in the middle part,which can be used as an indication of local tectonic stress transformation or concentration.The main faults in the Jinma-Yazihe area started in the early Indosinian period,continued to deform in the late Indosinian movement and strongly moved in the Yanshanian period.The Guankou and Pengxian faults thrusted strongly in the Yanshanian period,and continued to deform from the Himalayan to the neotectonic period,resulting in strike-slip and affecting the surface.Structural activities are closely related to hydrocarbon accumulation and contribute to the formation of structural traps,reservoir transformation,hydrocarbon migration and accumulation.