A water control technology for carbonate reservoirs, which uses heavy oil from Mordovo-Karmalskoye oil field (Republic of Tatarstan), has been developed. The technology can be realized in two options: heated heavy oil is mixed with oil-well Portland cement forming a slurry, or with highly oxidized bitumen, forming a melt. To prevent cooling of the injected slurry/melt, heat-insulated pipes are used.