Research and application of well wall-protecting slurry in drilling in complex formation of coal measures

Starting from the point of view to solve the difficulties of drilling, the paper studies the well wall protecting slurry in coal-bearing complex formation. Through the indoor test study of bentonite-polymer slurry system, then adopting the method of orthogonal test, the optimization formula of wall-protecting slurry was obtained. Finally the slurry of high polymer of low solid phase was used in field test, achieved good results in well wall protection during drilling in coal-bearing complex formation.