METHOD FOR WELL CASING IN FLOW ROCKS Russian patent published in 1996 - IPC

FIELD: casing of oil and gas wells within the interval of rocks prone to plastic deformation. SUBSTANCE: method for well casing in flow rocks includes running of casing string with cementing collar into well. Cementing collar is lowered to the depth of flow rock bottom and cement slurry is injected into the casing string-borehole annulus below the bottom and roof of flow rocks. Nonsolidifying fluid is located in the interval of flow rock occurrence and is used in form of viscoelastic fluid with compressibility factor (β) determined by the condition , where ΔV is change of volume of casing string-borehole annulus in casing string deformation, cu.m; V_o is initial volume of casing string-borehole annulus, cu.m; g is pressure in casing string-borehole annulus. Viscoelastic fluid is located by its injection into casing string-borehole annulus through cementing collar after cement slurry located above the roof of flow rocks. EFFECT: higher reliability in casing of well within the interval of flow rocks. 2 dwg