生物聚合物甲基葡萄糖甙钻井液抑制机理

Inhibiting effect mechanism of biopolymer MEG drilling fluid.

为验证甲基葡萄糖甙对泥页岩的抑制作用,分别进行了甲基葡萄糖甙在黏土上的吸附实验、甲基葡萄糖甙对黏土层间距的影响实验、甲基葡萄糖甙对页岩膜效率影响实验。实验表明:甲基葡萄糖甙对膨润土有很强的亲和力,水溶液(30℃)甲基葡萄糖甙吸附量可达120%,与无机盐复配使用后,其吸附能力进一步增加;用7%NaC l+25%甲基葡萄糖甙处理天然蒙脱石,其晶层间距为1.77 nm,比用水处理的蒙脱石晶层间距(1.92 nm)小,其干样晶层间距比未处理原样(1.54 nm)也小,说明甲基葡萄糖甙盐溶液能减少水分子进入蒙脱石,起到抑制泥岩膨胀作用;用清水饱和岩心,8 d时岩心与水+7%NaC l溶液的渗透压达到最大值,两边高度差为4.3 cm,而用MEG饱和岩心,9 d时岩心与水+7%NaC l溶液渗透压达到最大值,两边高度差为6.7 cm,说明甲基葡萄糖甙可有效改善页岩的膜效率。现场应用,表明甲基葡萄糖甙钻井液有较好的抑制和防塌作用,是油基钻井液较好的替代品。

Biopolymer MEG has a hydroxy(-OH),which has a strong absorptive action on the shale,and MEG has a methyl(-CH3),which makes the MEG become semi-permeable diaphragm after absorbing.To have measured the MEG adsorptive power to bentonite,it is up to 120% at 30℃;After mixing MEG and inorganic salt,the MEG have a better absorptive power;MEG build-up a semi-permeable diaphragm by the good absorptive power;The montmorillonit layer interspacing is 1.92 nm,this value is 1.77 nm after handling montmorillonit using MEG,it demonstrate that littler water absorbed after handling using MEG.Film efficiency have been measured using shale film efficiency evaluator,the effect is improved after handling shale by MEG;MEG is key additive in the drilling fluid formula in Zheng-X 41 well and the result demonstrate that MEG have a good inhibitive effect.