Improve Oil Production From Tar-Impacted Reservoirs Using In-Situ Steam Generation and Ionic Liquids

One of the typical production challenges is occurrence of impermeable layers of highly viscous asphaltenic oil (known as tarmat) at oil/water contact within a reservoir. Tar forms a physical barrier that isolates producing zones from aquifer or water injectors. As a result of tar occurrence, is a rapid pressure decrease that can be observed in such reservoirs, increasing number of dead wells, and declining productivity. Another indirect consequence of Tar presence is poor sweep efficiency that leads to water cut increase by a drastic magnitude. An innovative approach was developed to establish better sweep efficiency, transmissibility and pressure maintenance of Tar impacted-areas using thermochemical treatment. The treatment consists of injecting exothermic reaction-components that react downhole and generate in-situ pressure and heat. The in-situ reaction products provide heat and gas-drive energy to mobilize tar, improve sweep efficiency and maintain flooding for better pressure maintenance. Typically, downhole heat generation through chemical reaction releases substantial heat which could be employed in various thermal stimulation operations. Nano/ionic liquids, high pH solutions, solvents and nano metals were combined with the exothermic reaction to improve tar mobilization. Based on lab testing, the new technology showed more recovery than conventional steam flooding. Permeable channels were created in a tar layer with sandback samples, which enhanced transmissibility, pressure support and sweep efficiency. The effect of thermochemical treatment and ionic liquid on bitumen texture will be described. Impact of In-situ generated heat on injectivity will also be presented. The novel method will enable commercial production from tar-impacted reservoirs, and avoid costly steam flooding systems. The developed novel treatment relates to in-situ steam generation to maximize heat delivery efficiency of steam into the reservoir and to minimize heat losses due to under and/or over burdens. The generated in-situ steam and gas can be applied to recover deep oil reservoirs, which cannot be recovered with traditional steam, miscible gas, nor polymer injection methods.