Development of Associative Polymer Technology for Acid Diversion in Sandstone and Carbonate Lithology

Abstract

Abstract This paper describes the use of associative polymer technology (APT) to achieve fluid diversion during an acid stimulation treatment. APT involves the use of a very low-viscosity aqueous polymer solution. It reacts immediately with the formation surface to significantly reduce the ability of subsequent aqueous fluids to flow into high-permeability portions of the rock. The first stage containing the APT predominately will enter the most permeable area, diverting following acid stage(s) to less permeable sections of the rock. APT has little or no effect on the flow of subsequent hydrocarbon production. Furthermore, in rock containing significant proportions of sandstone-type lithology, the water permeability of the treated zone is decreased permanently, resulting in post-treatment reduced water production from the treated zone. This paper includes a general description of associating polymers and their properties, as well as a detailed description of the laboratory development of the current system. Laboratory data showing the ability of APT to reduce the ability of aqueous fluids to flow through porous media is presented. Parallel flow studies using water-saturated and oil-saturated cores are presented that show the ability of APT to divert acid in both sandstone and carbonate cores. These tests also show the ability of APT to decrease water permeability in the water-saturated core while the diverted acid increases the permeability of the oil-saturated core.