Experimental study and application of gels formed by nonionic polyacrylamide and phenolic resin for in-depth profile control

Abstract

Abstract A phenolic resin cross-linked nonionic polyacrylamide (NPAM) gel used for in-depth profile control was systematically analyzed. Long gelation time and strong gel strength of the gel system was obtained by adjusting NPAM or cross-linker concentration. An increase in temperature and salt concentration accelerated the gelation process and improved the gel strength. Although shearing brings a negative effect on gel performance, the gel system still had strong gel strength which could make it long-term stability in in-depth formation. Differential scanning calorimetry determined that this gel system should be used for oilfield application at temperatures below 143 °C. A compact three-dimensional network structure was formed in the bulk gel system and in porous media which contributed to long-term gel stability in the formation. Sand-pack flow experiments showed that the NPAM gel had a good plugging capacity and could selectively plug high permeability zones. By retention, adsorption, and bridging across the pore throats, the gel systems effectively reduced the permeability of porous media in high permeability zones and diverted fluid into low permeability zones, and thus improved the formation profile. Furthermore, this gel system for in-depth profile control treatment was successfully used in the Xinjiang oilfield of China which provided a reference for other similar high water cut oilfields for water control worldwide.