断层岩发生张性破裂所需压力预测及油田安全生产建议: 以秦皇岛33-1南和33-2油田明下段控藏断裂为例

为了确保秦皇岛33-1南和33-2明下段油田的安全生产, 在实测围岩抗压强度和区域应力场特征研究的基础上, 采用把断层岩看作倾斜岩层, 再与围岩对比的方法, 建立了一套断层岩发生张性破裂所需压力的预测方法, 并利用该方法对秦皇岛33-1南和33-2油田主要目的层——明下段控藏断裂断层岩发生张性破裂所需压力进行了预测.结果表明: 秦皇岛33-1南和33-2油田明下段控藏断裂断层岩发生张性破裂所需压力为25.6~31.3 MPa, 平均为29.4 MPa.如果油田开发过程中注水压力经过从注水井至断裂带压力损失后仍小于25.6~31.3 MPa时, 秦皇岛33-1南和33-2明下段油田可安全注水生产; 否则将造成该油田中的断裂发生张性破裂, 油沿断裂向上逸散至海底. 

Forecasting of Pressures Required in Tension Fracture of Fault Rock and Suggestions for Safe Production in Oilfield:An Example from Faults Controlling Oil Accumulation of N1m 1 in Qinhuangdao 33-1S and Qinhuangdao 33-2 Oilfields

To ensure safe production of Qinhuangdao 33-1S and 33-2 oilfields, based on the study of test of crushing resistance intensity and regional stress characteristics, a method forecasting pressure required in tension fracture of fault rock is proposed in this paper by using fault rock as a dip rock and contrasting between fault rock and surrounding rock. The new method is tried in forecasting pressures required in tension fracture of fault rock of faults controlling oil accumulation of N₁m₁ in Qinhuangdao 33-1S and Qinhuangdao 33-2 oilfields. Results indicate that pressures required in tension fracture of fault rock of faults controlling oil accumulation of N₁m₁ is 25.6-31.3 MPa, with the average value of 29.4 MPa. It is found that safe production can be guaranteed in Qinhuangdao 33-1S and Qinhuangdao 33-2 oilfields if water injecting pressure is smaller than 25.6-31.3 MPa after it is reduced from water injection well to fault. Otherwise, oil might escape to sea bottom from fault.