Bio-Chemical Desensitization and Viscosity Reduction System for Ultra-Sensitive Heavy Oil Reservoirs in Jinjia...

The Jinjia oilfield in Shengli oilfield is a typical ultra-sensitive reservoir characterized by high crude oil viscosity, poor fluidity, high clay content, and weak cementation. During development, oil-sand mixtures readily plug pore throats. Various development methods including water flooding and thermal recovery have been implemented, yet severe problems persist: inability to inject, failure to displace, and lack of capacity to produce. To address these challenges, a functional microbial mineral-modified desensitization-chemical viscosity-reduction dual-effect agent, a self-growing gel dispersion profile control agent, and a low-damage deep acidizing system were developed. Laboratory experiments clarified the enhanced oil recovery mechanism of the bio-chemical desensitization and viscosity-reduction system. Results indicate that the desensitization and viscosity-reduction system can inhibit clay swelling, with the anti-swelling improvement rate of core permeability reaching 56%. Chemical viscosity reduction enabled heavy oil to "flow effectively," achieving a viscosity reduction rate of 98.9% after adsorption. The profile control agent dispersed and migrated, then stably adsorbed onto particle surfaces to plug high-permeability channels, demonstrating strong anti-scouring capability and effectively suppressing channeling flow. In the composite system, bio-chemical desensitization and viscosity reduction synergistically enhanced mobility control, achieving an oil recovery factor of 56.5%, representing a 26.3% increase over post-water-flooding viscosity-reduction flooding. After two pilot well groups in the Jinjia oilfield were converted from water flooding to bio-chemical desensitization and viscosity-reduction composite flooding, single-well oil production capacity increased by 2.8-fold, water cut decreased by 12%, and both development performance and economic benefits were significantly improved-transforming the situation from "increasing water without increasing oil" to "increasing both liquid and oil production." The research findings provide important reference value for the effective development of ultra-sensitive reservoirs.