Modified bio-surfactant cationic alkyl polyglycoside as an effective additive for inhibition of highly reactive shale

The wellbore instability caused by shale hydration in highly reactive shale formation is a troublesome problem during oil and gas drilling process. In this study, cationic alkyl polyglycoside (CAPG) was synthesized by the etherification of C4 APG and applied to inhibit shale hydration. Using a highly reactive shale sample, the inhibiting performance of CAPG was studied by mud ball-immersing test, linear swelling test, shale recovery test, and bentonite inhibition test. The inhibiting mechanism was studied by experiments of surface tension, contact angle, particle size, XRD, SEM and FTIR. Evaluation experimental results proved that CAPG had the best inhibition performance for highly reactive shale among inhibitors studied in this work. Especially, CAPG has a substantially higher shale recovery ratio of 87.08%, while the shale recovery ratio of water is merely 5.41%. According to the mechanism analysis, the excellent inhibition performances of CAPG could be explained in three aspects. First, CAPG could redu...