西湖凹陷Z构造断层封堵性研究

Study about the Sealing Capability of Faults in Z Structure of Xihu Depression

西湖凹陷Z构造受F3和F98两条断层控制,因此需要进行断层封堵性研究,以确定这两条断层是否利于油气保存,同时可以通过断层封堵性研究确定有效圈闭面积的大小,为后期井位部署提供依据。经过研究发现,F3断层H1上部和H3封堵能力较弱,其它部位封堵能力较强,F98断层H1封堵能力较差,其它部位封堵能力较好。并且同等埋深下F98封堵能力大于F3断层,说明F3断层侧向封堵能力较弱,按木桶原理,F3断层的封堵能力决定Z构造的有效圈闭幅度。

Z structure of Xihu depression is controlled by fault F3 and fault F98. Therefore, it is necessary to conduct study on the fault sealing capacity in order to make sure whether these two faults are favorable for hydrocarbon preservation. At the same time, through study on fault sealing capacity, the effective area of the trap can be determinated, which can provide the foundation for the planning of well location. It is found through study that the sealing capacity of fault F3 at the top of sand layer H1 and sand layer H3 is weak, and is stronger in other place. The sealing capacity of fault F98 at the top of sand layer HI is weak, and is stronger in other place. In addition, the sealing capacity of fault F98 is stronger than fault F3 at the same depth, which means that the lateral sealing capacity of fault F3 is weaker than fault F98. Base on the Cannikin Law, the effective trap closure of Z structure is decided by the sealing capacity of fault F3.