Sand-Consolidation Resins - Their Stability in Hot Brine

Four commercial in-situ sand-consolidation resin systems and one resin-sandpack system were tested for durability in hot [160°F (71.1°C)] flowing brine for up to 28 months, and in as much as 30 million PV brine. Brine was selected as the test fluid since it is considered to be more damaging than oil to the stability of resin-consolidated sand. Two epoxy and two furan systems were investigated. Other commercial consolidation techniques - e.g., involving phenol formaldehyde and phenolic furan resins described in the literature1 - have been recognized as effective sand-stabilization products; however, some limitations had to be placed on the scope of the study because of equipment and time limitations. Perhaps these techniques will be the subject of future investigations. Note that all processes evaluated in this investigation used silane coupling agents contained in the resinous materials. These agents increase the stability of sands consolidated by organic polymers.2 The overflush-catalyzed furan resin (System A) and the internally catalyzed epoxy resin (System D) demonstrated greater stability under the specific test conditions employed. System A retained higher strength during the first 15 million PV. Thereafter, System D appeared to be better. System A exhibited the highest initial permeability, and, after 5 million PV, Systems A, B, and D were about equal in permeability. From that point, the permeability of System A slowly increased, while decreasing for Systems B and D. The epoxy-resin sandpack (40- to 60-mesh sand) showed little change in compressive strength after exposure to more than 30 million PV of hot, flowing brine. Introduction The current energy situation emphasizes the importance of utilizing the most efficient completion and production techniques to maximize production. Higher rates of production often can create conditions that, if not anticipated, can lead to unnecessary workover expense. Oil production from unconsolidated sands continues to demand effective and long-lasting sand-control procedures. Gravel packing, while often the most economical sand-control process, presents problems in multiple-zone completions, where it is necessary to stop sand production from intermediate and upper producing zones without interfering with the production from lower intervals. In-situ consolidation of incompetent producing sands with resin allows production from upper intervals without sand-control equipment in the borehole that would hinder production from lower zones. Such procedures are recommended for intervals that have not already produced appreciable quantities of formation sand. In cases where formation sand has been produced, it is desirable to pack the zone with a closely graded, resin-coated sand. The resultant consolidated pack provides a strong, highly permeable medium between the incompetent formation and the borehole. Two types of resin being used in the industry for in-situ consolidation and resin-bonded sandpacks are furans and epoxies. It is important that any procedure involving the use of these resins results in effective, durable protection against the production of formation sand.