正电性钻井液体系研究与应用

钻井液技术的发展一直是围绕着如何更好地解决"地层井壁稳定"与"钻井液性能稳定"这一对矛盾而进行的。国内外现有的各种钻井液体系全部属于负电性钻井液体系,即钻井液体系的ξ电位为负值。负电性钻井液体系有利于其本身性能稳定而不利于井壁稳定,经常导致钻井事故的发生。而正电性钻井液体系可以解决井壁稳定、提高钻井速度、保护油气层等关键技术问题。为研究在正电性状态下分散的钻井液技术,实现钻井液正电性的根本转化,重点介绍了钻井液电性的转化、正电性钻井液配方及现场试验。理论和现场实践证明,正电性钻井液体系不仅有利于抑制地层黏土的水化膨胀和分散,提高钻井液的抗盐、抗钙污染能力,维持井壁稳定,而且对保护油气层有重要意义。

Study and Application of Electropositive Drilling Fluid System

Borehole stability and drill fluid performance stability remains to be a contradiction, while it’s essential to better resolve this problem for the development of drilling fluid technology. The various drilling fluid systems used domestically are all electronegative, i.e., the ξ potential is a negative value. This type of drilling fluid has stable performances while it does no good to borehole stability, and causes drilling problems frequently. Electropositive drilling fluid system can be used to keep the wellbore stability, improve ROP and protect oil/gas reservoirs. This paper focuses on the transmission of drilling fluid electrical property, formula of electropositive drilling fluid and field test, and it proves that besides its inhibition to clay hydration and dispersion, the electropositive drilling fluid can also improve the salt and calcium pollution resistance of drilling fluid, and good for reservoir protection.