平面双分支水平井分支连接处井壁稳定研究

针对潜在走滑型应力场中钻平面反向双分支水平井分支连接处井壁稳定性问题，根据岩石力学相关理论，依据Drucker–Prager 准则，建立了分支井连接部分有限元分析模型，并采用牛顿–拉普森平衡迭代法求解。结合某油藏某井区实际地质资料，研究了最大水平主应力和分支井筒井斜角对分支井连接部分井筒稳定性的影响。结果表明：最大Von–Mises 应力大小和出现位置受井筒平面与原地最大水平主应力之间的夹角和分支井筒井斜角共同影响；最大Von–Mises 应力随着井筒平面与原地最大水平主应力之间的夹角增大而增大，随分支井筒井斜角增大，先减小，后增大，在分支井筒井斜角约为15◦时，最大Von–Mises 应力取得谷值。

Borehole Stability Research of Plane Dual-opposing Laterals Junction

To solve the problem of borehole stability of the multilateral junction of dual-opposing laterals in potential strikeslipstress field，we establish the finite element analysis models of multilateral junction on the basis of some related knowledgein the rock mechanics theory including the Drucker-Prager principle，and solve it by the Newton-Raphson iteration method.According to the practically geological data of some reservoir，we studied the effect on the borehole stability of MultilateralJunction which results from the maximum horizontal principal stress and the deviation of the lateral wellbore. Results showthat the maximum Von-Mises stress increases with the angle between the wellbore plane and the maximum horizontal principalstress. However，results also show the maximum Von-Mises stress first decreases and then increases with the deviation of thelateral wellbore. The optimum deviation angle of branch hole is 15 degrees. So，we can draw the conclusion that the size andposition of the maximum Von-Mises stress are mutually affected by the angle between the wellbore plane and the orientation ofthe maximum horizontal principal stress and the deviation of the lateral wellbore.