With the complex and developed fault system of PL Oilfield,fault sealing property of representative faults in PL Oilfield was studied by lithologic juxtaposition method,shale gouge ratio method (SGR),OWC on the both sides of the fault and oil property under an original state.The initial pressure data of the oilfield was used to study the fault sealing property after the development of the oilfield.The paper makes clear the fault sealing property in different periods and the reason for the change of fault sealing property.The results show that strike-slip fault and normal fault were closed in original state,but fault sealing weakness zone existed in partial fault.With the development of the oilfield,the pressure balance between the blocks was gradually destroyed,and the sealing ability of the partial fault was weakened,finally,the fault opened.The fault sealing weakness in partial fault,the pressure difference caused by long-term production on the one side of the fault and non-development on the other side,are the two major reasons that lead the fault to open finally.The applicability of fault sealing property research methods in PL Oilfield shows that SGR method is applied to fault with relatively small fault throw and lithologic juxtaposition method is applied to fault with different fault throw.%PL油田断裂系统发育,断层复杂.采用岩性对置法、断层泥比率法等直接法和测试断层两侧油水界面、原油性质等间接方法,对PL油田典型断层原始状态下的封闭性进行分析,并应用油田原始压力数据针对开发过程中断层的封闭性变化情况,研究了断层在不同时期的封闭性,分析了断层封闭性改变的原因.结果表明,PL油田走滑断层和正断层原始状态下多处于封闭状态,但存在封闭薄弱区,随着油田的不断开发,断块间压力平衡逐渐受到破坏,断层局部封闭能力减弱,发生开启现象.断层在局部存在着封闭性薄弱区,断层一侧长期生产而另一侧未开发,导致断块间压差逐渐增大,是断层后期局部开启的主要原因.通过对PL油田断层封闭性研究方法的适用性分析得出,断层泥比率法通常适用于断距不大的断层封闭性研究,而岩性对置法则适用于不同断距的断层.
展开▼
