EXPERIENCE IN USING PRE-CROSSLINKED POLYMER SYSTEMS FOR ENHANCED OIL RECOVERY IN CARBONATE RESERVOIRS

Abstract

Recovering residual oil reserves and reducing the level of water cut in produced wells at minimal cost are urgent tasks for mature fields. In such conditions, the use of tertiary methods of reservoir stimulation is relevant, among which a significant share is occupied by chemical methods of enhanced oil recovery. The principle of using flow diverting technologies is to supply small rims of chemical reagents to the reservoir through the reservoir pressure maintenance system, aimed at reducing the permeability of water-flushed zones by installing a waterinsulating barrier in them and redirecting water filtration flows to reservoir zones that were not previously covered by flooding. In this paper, we consider the possibility of using the technology of water-swellable preformed particle polymer systems as flow-diverting reagents to increase oil recovery from reservoirs with complicated geological and physical conditions that limit the use of many reagents used in EOR. On the example of a reagent sample, which is a pre-crosslinked acrylamide polymer, which contains particles of clay powder (up to 40% wt.), The paper shows the results of laboratory study and experience in applying the technology based on the preformed particle polymer systems at one of the objects of the Ural-Volga region, the reservoirs of which are presented carbonate rocks. The filtration experiment showed that the injection of the preformed particle polymer systems leads to a significant redistribution of fluid flows from a more highly permeable model to a less permeable one. As a result of the research, the main features of the applicability of technology based on the preformed particle polymer systems have been identified. The analysis of the conducted field work was carried out by determining the change in the injectivity profile of the treated injection wells and estimating the additionally produced oil from the reacting production wells. Based on the results of the analysis, additional laboratory studies were carried out, on the basis of which ways were proposed to increase the efficiency of injection well treatments with preformed particle polymer systems.