无粘土相正电性钻井液完井液体系研究

Study on clay free electropositivity drilling & completion fluid

研究了无粘土相正电性钻井液完井液配方,该钻井液完井液是一种在正电状态下分散的胶体体系,全部由阳离子处理剂配制而成。对无粘土相正电性钻井液完井液的ζ电位变化规律、流变参数、抑制性、抗高温、抗粘土污染、抗盐污染及保护油气层等进行了试验。结果表明,该体系具有独特的性能,ζ电位大于20 mV,具有极强的抑制粘土分散能力,能够最大限度地避免粘土颗粒侵入油层而造成的损害;ζ电位高,胶体稳定,流变参数等各项性能指标均能满足现场施工要求;阳离子处理剂能保持钻屑的不分散,有利于钻屑的清除;随粘土量的增加,吸附阳离子聚合物的量也随之增加,由于阳离子聚合物有效浓度的降低,所以正电性钻井液完井液粘度下降;无粘土相正电性钻井液完井液具有很好的保护油气层效果,能有效抑制油层粘土膨胀,渗透率恢复值高,适应于强水敏油层及易造成固相伤害油层的开发。

The formulations of clay free electropositivity drilling & completion fluid which is a positive dispersive colloid system confected by whole cation treating compound have been studied. And its changing tendency of zeta potential, rheological parameter, inhibition, temperature tolerance, clay and inorganic salt contamination ability and reservoir protecting have been tested systematacially. The results show that the system has many unique performances: superpower inhibiting clay dispersibility and effectively avoids invasion of clay particle to reservoir because of higher zeta potential (over 20 mV) ; colloid stability and rheological parameters satisfy requirements of field operation; cation treating compound keeps cuttings non-dispersed so that adequately facilitates hole cleaning; viscosity decreases with the decrease of effective concentration of cationic polymer because of absorbed amount of cationic polymer increases with the increase of clay; good protecting reservoir ability; inhibiting clay expanding in oil layer and high permeability recovery, etc. . Also, the system is good for the development of those formations with severe water sensitivity and solids damages.