【摘要】 页岩气水平井钻井使用旋转导向工具后，井壁掉块卡钻事故时有发生。为此，结合现场井壁掉块形状和大小，利用球面填充法建立掉块模型，借助计算流体力学软件Fluent和离散单元法软件EDEM,研究了掉块运移的影响因素。数值模拟结果表明：在现场施工排量条件下，遇阻掉块运移离开旋转导向环空时间为5～15 min,当钻井液排量大于35 L/s时可显著提高掉块的运移速度；增加钻井液密度会使掉块摆脱遇阻，为预防卡钻建议将钻井液密度维持在1.9 g/cm~3以上；当钻井液黏度为20～60 mPa·s时，其对环空中可活动掉块的运移有一定促进作用，但不影响已经遇阻和遇卡掉块。所得结论对预防水平井钻井中，旋转导向工具井壁掉块卡钻和钻井液安全循环时间制定具有一定的理论指导作用。更多还原

【Abstract】 Block sticking accidents often occur when rotary steerable tool is used in shale gas horizontal well drilling.Therefore, based on the shapes and sizes of falling blocks, the model of falling blocks was established by using the spherical filling method.By means of the computational fluid dynamics software Fluent and the discrete element method software EDEM,the influencing factors of falling block migration were studied.The numerical simulation results show that, at the displacement of field operation, the time for the falling blocks to move out of the annulus of rotary steerable tool is about 5～15 min.When the drilling fluid displacement is larger than 35 L/s, the migration speed of falling blocks can be increased significantly.Increasing the drilling fluid density can prevent the falling block sticking.Therefore, it is suggested to keep the drilling fluid density higher than 1.9 g/cm~3 to prevent sticking.When drilling fluid viscosity is 20～60 mPa·s, it helps to migrate the movable falling blocks in the annulus, but it has no effect on the stuck falling blocks.The conclusions provide some theoretical guidance for prevention of falling block stuck in the rotary steerable tools and for determination of safe circulation time of drilling fluid in horizontal wells drilling.更多还原