Anti-channeling High Density Cement Slurry Technology for Horizontal Shale Gas Well in Weiyuan

High formation pressures, long cementing hole sections, big temperature differences between surface and bottom hole, and high energy perforation and multi-stage fracturing in later period prevail in well cementing jobs in Weiyuan area where shale gas wells have been drilled. A high density anti-channeling cement slurry is developed to solve these problems. The cement slurry is formulated with filter loss reducer DRF-2120L, high temperature retarder DRH-200L, high temperature stabilizer DRK-3S, latex anti-channeling agent DRT-100L and purified iron powder, with the density ranging in 2.20-2.40 g/cm³. This cement slurry has good stability (density difference between the top and the bottom is zero), good mobility, no free water, low filter loss (<50 mL), low elastic modulus (<7 MPa), moderate compressive strength and strong anti-channeling capacity. (transit time <10 min, SPN=1.47-1.80), satisfying the needs for shale gas well cementing in south Sichuan. This cement slurry has been applied on 13 wells in Weiyuan till the end of March, 2015. Till the end of June, 2015, 4 wells of the 6 electric-logged wells have been successfully cemented, and the other two cemented up to scratch.