地层孔隙压力对井壁附近应力分布的影响

利用莫尔-库仑准则分析了地层孔隙压力对井壁附近应力分布的影响，模拟了井眼周围介质发生形变后地层孔降压力的变化模式，计算了地层孔隙介质在弹、塑性条件下，井壁发生屈服的塑性半径，从定量的角度证实了孔隙压力是影响井壁失稳的主要因素．分析认为，在假设井壁周围应力集中，地层孔隙压力是非均匀的、变化的条件下，裂缝内或孔隙内流体的流动是孔隙压力传递的途径，井眼周围的受力及介质特性的变化是导致井眼不稳定的主要原因．

INFLUENCE OF PORE PRESSURE ON STRESSES DISTRIBUTION AROUND A BOREHOLE

The influences of pore pressure on the stresses distribution around a borehole are studied by using Mole-Coulomb critaria. The pote pressure changed when the proe mediums around borehole had deformated. The pressure distributions are simulated, and the yielding plastic radius are calculated. The conclusions showed that the pore pressure is the major influence factor on the instability of borehole. The changes of pressure and the pore medium property around the borehole are are the main factors resulting in instability of the borehole.