Abstract:
Objective To mitigate the wellbore instability due to mud shale hydration expansion in high-temperature environment during deep and ultra-deep wells drilling, the research on temperature-resistant shale inhibitors is carried out.
Method A novel shale inhibitor (PKAD) with both green and inhibition properties was synthesized via aqueous polymerization using hydroxypropyl-β-cyclodextrin, a green polysaccharide, along with γ-methacryloyloxypropyltrimethoxysilane, acrylamide, and diallyldimethylammonium chloride as reaction monomers. The molecular structure was characterized by FTIR and H NMR; the inhibition performance of PKAD was evaluated through experiments such as linear expansion and rock debris rolling recovery; and its biodegradability was also studied.
Result The material characterization confirmed the successful synthesis of PKAD, and the evaluation experiment demonstrated that PKAD could significantly reduce linear expansion by over 70%. The hot rolling recovery rate of rock debris at 160 ℃ was 92.6%, and the rolling recovery rate of rock debris at 200 ℃ was 85.7%. Mechanism studies showed that PKAD could achieve inhibitory effects by reducing the negative charge on the clay surface and enhancing the hydrophobicity of the clay surface. Additionally, the BOD5/CODCr ratio of PKAD was 0.31, indicating its biodegradability.
Conclusion PKAD prepared by refining hydroxypropyl-β-cyclodextrin has good inhibition and temperature resistance properties, which has a certain guiding significance for the modification of natural materials.