辽中南洼西斜坡断-盖耦合类型及其控藏作用——以旅大A油田为例

为弄清辽中凹陷南次洼西斜坡的油气分布规律,利用三维地震数据和钻井资料,对旅大A油田的盖层与油源断裂发育特征进行系统研究,从而明确了研究区断-盖耦合类型及其对油气成藏的控制作用。研究结果表明,研究区不同构造断-盖耦合类型差异悬殊,断-盖耦合关系对油气富集层系具有明显控制作用。其中:北部A-1构造断-盖耦合类型为封闭型,油源断裂与盖层耦合关系较好,有效断接厚度较大(278 m),大于有效断接厚度封油的临界值(100~150 m),油气被完全封盖在盖层之下的东三段储层;而南部A-2构造断-盖耦合类型为半封闭型,油源断裂与盖层耦合关系差,有效断接厚度小(98 m),部分油气沿油源断裂垂向运移,在盖层之上的东一段和东二上亚段储层富集。

Spatial matching types between faults and caprock and their controlling effects on hydrocarbon accumulation of western slope in southern Liaozhong Sag: taking Lyuda A Oilfield as an example

In order to study the oil and gas accumulation law of the western slope in the southern Liaozhong Sag,3D seismic data and drilling data were used to study the characteristics of caprock and oil source faults in the A Oilfield systematically,and eventually the spatial matching types between the caprock and oil source faults and their controlling effects on the hydrocarbon accumulation were understood.The results show that the matching types between the source faults and the caprock are very different among the different structures of the study area and the matching relationship between oil source faults and caproek has a clear controlling effect on the hydrocarbon accumulation.Among the structures,the matching type of the northern A-1 Structure is the fully-covered type with good matching relationship between the oil source faults and caprock and larger effective juxtaposition thickness (Hf average=278 m),which is greater than the critical value of effective fault thickness (100-150 m),so oil and gas is completely sealed in the third Member of Dongying Formation reservoir under the caprock.While the matching type between the source faults and the caprock of the A-2 Structure in the southern part is the semi-covered type with the worse matching relationship and the smaller effective juxtaposition thickness (Hf average=98 m),so oil and gas can migrate along the oil source faults vertically and accumulate on the first and the upper second Member of Dongying Formation reservoir.