As proppant particles exit fractures during production, the fracture conductivity diminishes with time as the fracture width decreases. This choking effect causes the production of the well to decline, and the high velocity of proppant particles also damages downhole or surface equipment. As a result, proppant flowback causes significant costs resulting from loss of production and equipment damage. Wells experiencing these problems require remediation, ranging from routine wellbore cleanouts to costly artificial lift equipment repairs.
A novel, water-based consolidation system has been successfully developed to overcome fluid compatibility, placement, and safety issues during handling and operations, which most current conventional solvent-based resins encounter during field applications. In this system, solvent-based chemicals are replaced with aqueous brines as carriers in the treatment fluid. As a result, aqueous-based resins have high flashpoints, similar to those of water. Additionally, aqueous-based systems are essentially noncombustible and contain no solvent-based resins. They can be foamed, so the operator can bullhead the fluid directly into the wellbore to treat long intervals without zonal isolation packers.
The new aqueous-based resins were field tested in Western Desert, Egypt for the first time in 2009. They were developed to provide consolidation for previously placed proppant near the wellbore without damaging the permeability of the proppant pack. Shrouk field wells were hydraulically fractured, and the initial production was approximately 1,000 BOPD. Eventually, the wells began producing proppant, and within three days, proppant flowback destroyed the production pump and eliminated the benefits associated with good wells. Cleaning the wellbore did not prevent the recurrence of proppant flowback, and the cleanup process was repeated several times to maintain well production.
Results from field trials showed that this aqueous-based consolidation (ABC) system successfully treated proppant in near-wellbore (NWB) regions, locking them in place without damaging production flow paths. The consolidation treatment transformed the loosely packed proppant in the fractures near the wellbore into cohesive, consolidated packs. In these field tests, intervals in excess of 40 ft were treated effectively with a bullhead squeeze, using consolidation treatment fluids that were foamed to a quality of 75% to aid in diverting treatment fluids and extending treatment volume.
This case history presents results of the application of the ABC system to control proppant flowback and to enhance fracture conductivity in Egypt's Western Desert oil fields. This paper presents the results of field applications and discusses the challenges, treatment procedures, and recommendations for applying this newly developed resin. The excellent proppant flowback control reduced remedial work by 95%, and proppant flowback issues were resolved, resulting in significant cost savings.
