LAUSR

Water flooding as the dominant method to improve oil recovery has been widely applied to most oilfields in the world; however, excess water production has become a major problem for reservoirs that have been flooded by water for many years. The objective of this paper is to prepare and evaluate a novel strong gel that can be used to significantly reduce the permeability of the fluid channels resulting from water flooding. We developed a novel fluid diversion agent called CPP gel, which is a semi-interpenetrated networks gel cross-linked by acrylamide grafting onto sodium carboxymethyl cellulose/polyglycol. The paper investigated its applicability with the Bohai offshore oilfield reservoir conditions. The gel properties, including the rheological performance and blocking efficiency, as well as its influencing factors were investigated. The results showed that the CPP had less injection pressure but higher blocking efficiency than conventional polymer gels, and its blocking efficiency was dependent on the gel components, temperature, water salinity, rock permeability and rheological properties. The decrease in the network chain length, the increase in the interactions among molecules and the increase in the uniformity of the overall network structure could contribute to the enhanced blocking mechanisms. [Received: February 7, 2015; Accepted: January 28, 2017]