泥浆密度对裂缝性油藏力学损害机理室内模拟试验研究

方法：采用常规三轴岩石强度试验装置，进行井下温度压力条件下的泥浆侵入过程模拟试验。目的：观察不同泥浆密度条件下井下天然裂缝的开闭状态，张开度及泥浆侵入裂缝的过程和深度。结果：随着泥浆密度的增加，裂缝张开的最大距离和张开的区域减小，当泥浆密度达到临界值时，节理完全闭合，继续增大泥浆密度，裂缝张开的最大距离和张开的区域也增大，当裂缝有充填物时，随泥浆柱压力增加，泥浆侵入深度增大，当泥浆柱压力超过第一临界值后，侵入深度急剧增大，结论：在条件允许的情况下，应尽量降低沉浆密度，使力学损害降至最低，泥浆柱压差应小于10MPa，以使泥浆侵入深度控制在较小范围内，减少油气层损害。

In-doors simulated experimental study on mechanical damage mechanism of mud density on fractured reservoir

Method Mud invasion process is simulated with conventional three axis rock strength test device under same downhole pressure and temperature. Purpose To observe opening status and mud invasion process of downhole natural fractures under various mud densities. Result Maximum distance of fracture propagation and area are enlarging with the increase of mud density. In case there is filling agent inside fractures, mud invasion depth increases significantly with the increase of mud column pressure. Conclusion Mud density should be reduced as much as possible to minimize mechanical damage. Mud column. pressure difference be lower than 10 MPa to allow mud density invasion depth and its damage on formation under control.