Understanding the formation damage surrounding the well during the drilling operation is the key to predict damage degree and protect the formation in oil/gas reserviors. Based on the core drainage results, we obtained an empirical relationship between the invasion volume of drilling fluid and permeability reduction of formation. Furthermore, the equation is incorporated into a commercial reservior numerical simulation simulator to characterize the behaviors of drilling fluid invasion process. The results show that, although the invasion depth in low permeability reservoirs is short with the range of 1.7–2.5 m, the effect on recovery factor is significant due to the narrow seepage area in the near fracture region. When considering the formation damage, the pressure in the near-fracture damage region drops sharply, leading to a three-stage shape in pressure distribution curve. In addition, we found that high viscosity and low density oil-based slurry and shorter soaking period are conducive to decrease the formation damage during drilling operation. This work reveals the fundamental mechanisms of formation damage in low permeability reservoirs, which is a theoretical basis in formulation drilling fluids and optimization operation parameters.

了解钻井过程中井周围的地层损害是预测损害程度并保护油气储层中地层的关键。根据岩心排水结果，我们得到了钻井液侵入量与地层渗透率降低之间的经验关系。此外，该方程式被合并到商业储层数值模拟模拟器中，以表征钻井液入侵过程的行为。结果表明，尽管低渗透储层的侵入深度较短，范围为1.7-2.5m，但由于裂缝附近的渗流区域狭窄，对采收率的影响是显着的。当考虑地层损害时，接近断裂损害区域的压力会急剧下降，导致压力分布曲线呈三阶段形状。此外，我们发现高粘度，低密度油基浆液和较短的浸泡时间有利于减少钻井作业过程中的地层损害。这项工作揭示了低渗透储层地层损害的基本机理，这是配制钻井液和优化作业参数的理论基础。