Successful Shale Drilling Using a New Environmentally Compatible Potassium Carbonate/Polymer/PolyGlycol Mud System: Design and Field Experiences

Abstract

This paper presents laboratory data and field application results on a new water based mud system which utilizes Potassium Carbonate, a special polymer formulation and a polyglycol. The surfactant properties of the polyglycol around it's cloud point, the existence of normal force and extensional viscosity in the mud prepared under low shear, and the successful application of the mud system in southern Italy to drill massive shale sections with high kaolinite clay content are all discussed. P. 135

Water-Soluble Acrylamide Sulfonate Copolymer for Inhibiting Shale Hydration

“…Polyacrylamide (PAM) and partially hydrolyzed polyacrylamide (HPAM) are widely used in drilling fluids and their long molecules can absorb on the clay surface to protect the clays from dissolution in water to some extent. − During the past decades, many water-soluble polymers have been used as clay stabilizers in drilling fluid systems to inhibit the hydration and keep the rock strength. The water-soluble polymers used so far include polyacrylonitrile ammonium salt (NH 4 –HPAN), calcium polyacrylate, cationic polymers, , zwitterionic polymers, , and polyglycols. , However, most of them showed only very limited ability to inhibite hydration of clays or shale under high temperature and/or salinity conditions . Recent efforts have shown that copolymers of acrylamide (AM) or substituted acrylamides with a suitable functional monomer, such as 2-(acrylamide)-2-methylpropane-1-sulfonic acid (AMPS) or N , N -diallylbenzylamine (NAPA) exhibits considerably improved temperature-resistance and salt-tolerance.…”

“…The water-soluble polymers used so far include polyacrylonitrile ammonium salt (NH 4 −HPAN), 10 calcium polyacrylate, 11 cationic polymers, 12,13 zwitterionic polymers, 14,15 and polyglycols. 16,17 However, most of them showed only very limited ability to inhibite hydration of clays or shale under high temperature and/or salinity conditions. 18 Recent efforts have shown that copolymers of acrylamide (AM) or substituted acrylamides with a suitable functional monomer, such as 2-(acrylamide)-2-methylpropane-1-sulfonic acid (AMPS) 19 or N,N-diallylbenzylamine (NAPA) 20 exhibits considerably improved temperature-resistance and salt-tolerance.…”