准噶尔盆地西北缘下盘掩伏构造油气勘探新领域

New hydrocarbon exploration areas in footwall covered structures in northwestern margin of Junggar Basin

准噶尔盆地西北缘冲断构造自西向东由北部单斜带、中部向斜带、克—乌断裂带和前缘斜坡带4个部分组成,在纵向又可划分为上、下两个构造层,上构造层的冲断序列要先于下构造层。现今保存下来的冲断构造应始于三叠纪末期形成,并在侏罗纪继承性活动,白垩纪之后冲断活动基本停止。西北缘冲断带下构造层内的背斜圈闭和"帽檐"式圈闭是油气勘探前景很大的新领域,尤其是大侏罗沟横向断裂与克—乌断裂带夹持的三角区域,"帽檐"圈闭埋藏适中,是一个有利的勘探目标。应在获得必要的深部地质资料和速度资料后,再针对保存完整、面积和幅度均较大的下盘掩伏背斜开展地震处理攻关与解释成图。

The fold-and-thrust structure in the northwestern margin of the Junggar Basin is composed of the northern monocline belt, the middle syncline belt, the Ke-Wu faulted belt and the frontal slope belt, and is divided into the upper and lower structural layers in vertical. The upper structural layer preceded the lower one in terms of thrust sequence. Inferred from the restoration of unconformities, the motion of thrust faults started in late Triassic, activated in succession in Jurassic, and stopped in Cretaceous. The footwall venture exploration should aim at ＂cap brim＂ traps, especially in the triangular region, where the Dazhuluogou tear fault and the Ke-Wu thrust belt intersect and the exploration horizon imbeds moderately, and then aim at the deep anticlinal traps in duplex structures when obtaining the essential data of deep geology and velocity data.