Deep Penetration Resin Systems Overcome Annular Gas Migration: Case History

Well Integrity is a critical compliance requirement during oil and gas operations. Abandonment procedures must ensure that all hydrocarbon sources are properly isolated and effective barriers are placed. This paper describes the use of resin systems to isolate annular gas migration identified during the Obiwan – 1 well abandonment in Colombia. The main challenge was to select and design fluid systems capable to fill tight spaces and isolate the annular channel. Resin systems are high-strength, elastic polymers which act as dependable barriers to isolate fluid flow. They can be designed as a solid-free, pure liquid or may contain solids (cement with a formulated percent of resin). Solid-free formulations are ideal for remedial operations, such as isolating annular gas. Acoustic logging enabled identification of the influx zones. Annular isolation was achieved by executing two cementing remedial operations using the bradenhead squeeze technique. A tailored resin system was selected to deliver the proper barrier addressing the influx zones after injectivity tests were performed in each interval. For the first intervention a solids-free resin system was used, and for the second one a resin-cement composite system was applied. During cementing remedial operations, it was determined that the resin systems were able to achieve deep penetration into the channels more readily and form a seal. The correct system was selected for each case, and during execution, the required volume was injected to intersect and properly isolate the annular gas channel. As a result, the tailored resin systems isolated the gas channel eliminating annular pressure and gas migration to surface. In addition, a post remedial operation acoustic log indicated that the influx zones were successfully isolated. Well abandonment was accomplished according to country regulatory requirements and delivered dependable barriers both annular and interior pipe sections. Use of resin to repair channels of this type exhibited a higher success rate and improved reliability in comparison to conventional particulate-laden fluids, which helps to decrease costs for additional remedial treatments.