适合低渗透油藏的高效水基钻井液体系研究

High-Efficiency Water-Based Drilling Fluid System Suitable for Low Permeability Reservoir

针对海上某低渗透油藏前期使用钻井液体系存在的不足,结合目标油田实际情况,研制了一种适合低渗透油藏的高效水基钻井液体系,并对其综合性能进行了评价。结果表明,该钻井液体系具有良好的耐温性能,在140℃下滚动老化后体系的流变性能及滤失量等各项性能基本没有变化;该钻井液体系具有良好的防水锁性能,当防水锁剂HAW-1加量为1.5%时,钻井液滤液的表面张力、界面张力分别降至27.5 mN·m^(-1)、7.5 mN·m^(-1);该钻井液体系具有较强的抑制性能,对目标油田储层段岩屑的滚动回收率可达到90%以上;该钻井液体系具有较强的抗污染性能,当劣质土加量为20%时,钻井液体系的各项性能参数仍能保持稳定;另外,该钻井液体系还具有良好的储层保护性能,使用钻井液污染后,目标油田储层段天然岩心的渗透率恢复值可达到85%左右。

Aiming at the shortcomings of the drilling fluid system used in the early stage of a offshore low permeability reservoir,combining with the actual situation of the target oilfield,we developed a high-efficiency water-based drilling fluid system suitable for low permeability reservoir,and evaluated its comprehensive performance.The results show that the rheological properties and filtration loss of the drilling fluid system have no changes after rolling aging at 140℃,which indicates that the drilling fluid system has good temperature-resistance performance.When the addition of waterproof locking agent HAW-1 is 1.5%,the surface tension and interfacial tension of the drilling fluid filtrate can be reduced to 27.5 mN·m^(-1) and 7.5 mN·m^(-1),respectively,which indicates that the drilling fluid system has good waterproof locking performance.The rolling recovery of cuttings in the reservoir section of the target oilfield can reach more than 90%,which indicates that the drilling fluid system has strong inhibition performance.When the addition of poor soil is 20%,the performance parameters of the drilling fluid system can remain stable,which indicates that the drilling fluid system has a strong anti-pollution performance.In addition,the permeability recovery value of the natural core in the target reservoir section can reach about 85%after contamination by drilling fluid,which indicates that the drilling fluid system also has good reservoir protection performance.