Study on the Shale Stabilizer XAN-YZ

A water base drilling fluid for use in shale gas drilling was developed, and the effect of XAN-YZ, a shale stabilizer, on the rheology, inhibitive capacity and sealing performance of this drilling fluid was studied. When treated with 2% XAN-YZ, polymer sulfonate drilling fluid has improved shear thinning performance, reduced rate of swelling of shales by 40%, and increased percent recovery of shale cuttings in hot rolling test by 16%. Pressure bearing capacity of the formation drilled with this drilling fluid is increased from 2 MPa to 5 MPa. XAN-YZ generates dense mud cakes on the borehole wall, thus instantly heals and seals the fractures, beddings and pores found in shale formations, and increases the pressures for filtrates to penetrate the shale formation from 2 MPa to 15 MPa. Laboratory study shows that the optimum treatment of XAN-YZ in polymer sulfonate drilling fluid is 2%. This study provides a new technical clue and means for shale gas drilling with water base drilling fluids.