渤海湾盆地黄河口凹陷构造定量分析与油气富集耦合关系

The couple relationship of quantitative analysis of the structures and oil&gas accumulation in Huanghekou depression,Bohai Bay Basin

渤海湾盆地黄河口凹陷是小型富烃凹陷，郯庐断裂西支呈SN向穿越，造成目前已经发现的油气藏均与断裂构造活动有关。在采用断层活动速率定量分析断裂活动性的基础上，对古近纪以来黄河口凹陷断裂的发育期次、组合特点、成因机制等进行了研究和探讨。结果表明：新生代黄河口凹陷的断裂发育受控于郯庐断裂带的活动构造体系域；古近纪郯庐断裂右行走滑，则导致EW向伸展伴生断裂发育，形成了伸展构造、走滑构造和走滑伸展叠加构造样式；由郯庐断裂西支为界的黄河口凹陷不同次洼具有不同的构造活动特征以及油气富集程度，其中东部洼陷主要发育伸展走滑叠加构造，发育“Y”型和“卷心菜”型构造，最大断层生长指数在沙河街组三段一孔店组沉积期为1．2，其他时期构造活动弱，造成本次洼油气富集程度高；西北次洼主要发育伸展构造，发育“Y”型和地堑型构造，沙河街组三段和东营组沉积期断层生长指数为1．3～1．4，本次洼油气富集程度也较高；西南次洼主要受伸展构造影响，由于底部抬升作用的叠加，造成东营组断层生长指数达到1．9；沙河街组一段及沙河街组二段沉积期断层生长指数达到1．3，构造活动强烈，油气富集程度较差；中央隆起带属于郯庐断裂走滑构造带，发育“Y”型和负花状构造，在沙河街组沉积期断层生长指数为1．2，其他时期构造活动较弱，造成中央隆起带油气富集程度高。

Huanghekou depression in Bohai Bay basin is small but hydrocarbon-enriched. The west branch of Tan Lu fault is oriented south to north. Based on this, all the oil ~ gas reservoirs which have been found are closely associated with the structural activities. Moving velocity of the fault is adopted to analysis the fault activity quantitatively. Building further on this foundation, the development phase, combinations and genetic mechanism of the faults in Huanghekou depression since Paleogene have been most extensively studied and discussed. Results＇indicate that fault evolution in Huanghekou depression in Cenozoic is controlled by the structure activity system tract of Tan Lu fault. Tan Lu fault is dextral strike-slipping in Paleogene, which give rise to the associated fault EW strike. Whereupon the extensional, strike-slip, and strike-slip extensional superimposed structural styles are formed. In Huanghekou depression, of which the boundary is the west branch of Tan Lu fault,different sags have different tectonic activity characteristics and hydrocarbon accumulation degrees. In eastern sag, there mainly is strike-slip extensional superimposed structure. Suffering this impact, Y type and cabbage type structures developed. The maximum fault growth index is 1.2, which appeared in the period from the third section of Shahejie Formation to Kongdian Formation. The structural activity is weak in other periods, so the oil and gas accumulation degree is high. In northwestern sag, there are mainly developing extensional structure, Y type and graben type structures. The fault growth index range of the third section of Shahejie Formation and Dongying Formation is between 1.3 and 1.4. The oil and gas accumulation degree of this sag is also relatively high. Southwestern sag is mostly affected by extensional structure. A- long with the effect of the bottom uplifting, the fault growth index of Dongying Formation is 1.9. There in the first and second section of Shahejie Formation develops intensive structure activities. Its fault growth index is 1.3, and the oil and gas accumulation degree is lower. In central uplift belt, which belongs to strike slip tectonic belts of Tan Lu fault, there develops Y type and negative flower structures. The fault growth index in Shahejie Formation is 1.2, and in other periods the tectonic activity is weak, which creates a rich hydrocarbon accumulation in this belt.