低渗透油气层水锁损害机理及低损害钻井液技术研究

Researches on the Water Block in Low Permeability Reservoir and Minimized-reservoir-damage Drilling Fluid Technology

低渗透油田地层具有泥质胶结物含量高、含水饱和度高、毛细管压力高、水敏性强及孔喉细小、渗透性差、结构复杂、非均质严重、油气流动阻力大、常伴有天然裂缝等特点。大量的研究表明，水锁损害是低渗储层最主要、最严重的损害类型，损害率一般为70％～90％。从多种角度系统分析了水锁损害产生的根源及其主要影响因素，并针对钻井完井过程中的水锁损害问题，研制出了多功能、低伤害、超低渗透的两性离子聚磺钻井液。该钻井液抑制性强，能防止水锁损害，更好地保护地层，提高低渗透油气藏的综合开发效益。

Low permeability reservoirs have characteristics such as high argillaceous cement content,high water saturation,high capillary pressure,highly water sensitive,small pore throats,poor permeability,complex structures,highly inhomogeneous,and high resistance to flow,and often are accompanied by naturally fractures.Researches had proved that water block was the most important cause for permeability impairment,with impairment percent of 70%-90%.This paper analyzed from different aspects the sources and the influential factors of water block.An amphoteric polymer sulfonate drilling fluid was developed with multiple functions,minimal damage to reservoir permeability,and ultra-low filter loss.This drilling fluid is beneficial to the development of low-permeability reservoirs.