Development and Evaluation of Oil Base Mud Plugging Agent with Nuclei

An acrylic resin polymer was synthesized with monomers such as butyl acrylate, octadecyl acrylate, acrylic acid and styrene through modified emulsion polymerization. A modified organophilic silica flour was used as condensation nucleus. This synthesized polymer is a polymer with nuclei, and is used as a plugging and sealing agent in oil base drilling fluids to prevent mud losses and borehole wall collapse. It is of almost no influence on the rheology of oil base muds, and can greatly improve the capacity of oil base muds to build high quality mud cakes and the emulsion stability of oil base muds. Cores flooded with oil base mud formulated with this polymer have pore throats plugged by more than 75%, and breakthrough pressure can be as high as 10 MPa or higher. This plugging and sealing agent has excellent high temperature stability, the plugging performance remains almost unchanged before and after aging. As laboratory experiments indicated, this plugging and sealing agent is better than asphalt products.