低渗透储层多级架桥暂堵储层保护技术

水锁、水敏及碱敏等造成了低渗透砂岩储层渗透率难以恢复的伤害，成为了储层保护的技术瓶颈。为此，依据屏蔽暂堵技术原理，以岩心实验确定的对渗透率贡献最大的孔喉半径区间为依据，研制出了与储层孔喉渗透率贡献率分布相匹配的多级架桥暂堵油气层保护剂，它由多级架桥粒子FDPD和可变形粒子FEP组成，在钻井液中最佳加量分别为4%和2%～3%。室内对加入多级架桥暂堵油气层保护剂前后钻井液性能变化和岩心渗透率恢复值进行了实验评价。结果表明：①岩心渗透率恢复率达85%，能很好地保护低渗透储层；②多级桥架暂堵剂加入钻井液后，虽钻井液的黏度和切力有所上升，但波动不大，能够满足工程的要求；③中压滤失量和高温高压滤失量降低，更有利于储层保护。2口应用井与同区块其他井相比油气产量明显提高，起到了良好的储层保护作用。该技术具有低成本、施工方便等特点，是一种切实可行的低成本且安全可行的油气层保护方法。

Multi-level bridge plugging for the protection of low-permeability reservoirs

The water lock, water sensitivity and alkali sensitivity will result in irrecoverable damage to low permeability sandstone reservoir permeability, which becomes the bottlenecking problem of reservoir protection. Therefore, the range of pore throat radius with the most greatest contribution to the permeability was first determined in the core sample tests; then according to the principles of shielding temporary plugging, a multi level bridge temporary plugging agent was developed for oil & gas reservoir protection matched with the distribution of contribution rate of pore throat permeability. This newly developed agent consists of FDPD (multi level bridge particles) and FEP (deformable particles), the optimum amounts of which added to the drilling fluid are 4% and 2 ~ 3% respectively. The experimental evaluation was performed on the drilling fluid performance changes and core permeability recovery values before and after this agent was added. The following findings were achieved. a. The core permeability recovery reaches 85%, which is good enough to protect low permeability reservoirs. b. With this new agent added, the drilling fluid viscosity and shear force are increased slightly with little fluctuation, meeting the drilling requirements. c. The medium pressure filtration loss and high temperature high pressure filtration loss are both reduced, which is more favorable to reservoir protection. The actual application showed that the oil and gas outputs of the two pilot test wells are increased significantly compared with those of other wells in the same block and this technology is proved to function well in reservoir protection with a low cost and an advantage of easy and convenient operation.