Research On Technology Of Wellbore Stability In Yitong Area

In the drilling process,keeping wall stable is a difficult and complicated problem.The research of the wall stability experienced from the beginning of pure mechanics study,to the pure chemical study,and then to the mechanical and chemical coupling in recent years.While drilling,the wall In YiTong area always collapsed,the wall instability problem is becoming more and more serious and severely restrict the drilling and development process.Aiming at the problem,this paper studies the chemical mechanism,conducts the wall stability calculation and puts forward the corresponding measures to prevent the collapse.In the chemical study,we analyzed the strata rock mineral composition and the physical and chemical properties of the rock specimens in YiTong area by the tests of cation exchange capacity test,ratio water absorbing capacity test,rolling recovery test,expansion ratio test and activity test.Then we know that YiTong area get easy slump dilatability weaker strata,but local stress is bigger,dispersivity is strong and there's a crack.In the wellface stability calculation,we got rock mechanics parameters through indoor laboratory and logging data,and established the borehole stability mechanics model;analyzed and calculated the hydration stress.Finally we got the drilling fluid safety density range under the two kinds of salinity conditions by comprehensively using the logging data and indoor test data,and used all calculated well data to draw some charts.