天然气工业2018，Vol.38Issue(2)：83-89,7.DOI:10.3787/j.issn.1000-0976.2018.02.011
W/O型微乳酸前置冲洗液的制备及其性能研究
Preparation and properties of W/O microemulsified acid preflush
摘要
Abstract
During the drilling of shale gas horizontal wells,oil-based mud cakes generated from the oil-based drilling fluid can be hardly flushed down,and consequently the displacement efficiency of cementing is low and the cementing strength of the second interface is poor.In view of this problem,a formula of cementing preflush of W/O diesel-soil acid microemulsion was designed.This preflush is mainly composed of soil acid,long-chain quaternary ammonium salt C-223,and polyoxyethylene ether Z-15.Then,its flushing performance was evaluated and its microscopic mechanisms were analyzed by means of laboratory experiments.And the following research results were obtained.First,the microemulsified acid,with C-223 ∶ Z-15 =3 ∶ 2 as the primary surfactant,n-butanol ∶ n-octanol =1 ∶ 2 as the co-surfactant and diesel ∶ soil acid =5 ∶ 4,is stable and well compatible with the oil-based drilling fluid,and its flushing efficiency is up to 96.86％.Second,after it is flushed by the microemulsified acid,the interface contact angle alters greatly,the water phase wettability on the casing wall is increased significantly and no obvious corrosion occurs on the casing.Third,during the formation of the microemulsified acid,the system changes from a clear state to a turbid state with the increase of acid concentration.Besides,the volume of solubility improving acid is high and the reserved oil space is large.Fourth,the average diameter of the micro-particles involved in the Brownian movement in the mieroemulsified acid is about 21.2 nm.Fifth,the single-phase lateral relaxation time of both soil acid and diesel is distributed in the form of a single time peak and the relaxation time of soil acid is distributed within the range of diesel,so it is favorable for them to dissolve into a stable microemusified acid.It is concluded that this flush system can improve the wettability of the first and second interfaces effectively,altering the oil wet interface into the water wet interface,and thus it is favorable for the improvement of cementing displacement efficiency and cementing quality.关键词
微乳酸/固井/前置冲洗液/三相图/粒径分析/低场核磁共振/弛豫时间/界面润湿性/固井质量Key words
Microemulsified acid/Cementing/Preflush/Three-phase diagram/Particle size analysis/Low field nuclear magnetic resonance (NMR)/Relaxation time/Interface wettability/Cementing quality引用本文复制引用
彭志刚,钟明镜,冯茜,霍锦华,罗文嘉,刘高峰,张博建..W/O型微乳酸前置冲洗液的制备及其性能研究[J].天然气工业,2018,38(2):83-89,7.基金项目
国家科技重大专项“低渗透油气田完井关键技术”(编号:2011ZX05022-006). （编号:2011ZX05022-006）
