Billions of dollars are lost each year as a direct or indirect result of unwanted solids flowback with the production of hydrocarbons. These solids, whether formation sand, fines, or proppant produced from propped fractures, restrict well production by plugging sand screens, perforation plugging or collapse, or wellbore fill. They often cause damages to downhole and surface equipment and storage facilities. Workovers and shutdown time of the well contribute considerably to the frequent and costly cycle in solving, or at least managing, the solids-production problems. Often, the solids production becomes intolerable, especially in offshore environments.
Numerous studies have been performed to identify the mechanisms and causes of solids production. Both mechanical and chemical solutions have been applied to limit or to overcome the problems. This paper presents a detailed review of chemical technologies that have been successfully used for controlling solids production in the last decade, either as part of a primary completion or a post-completion treatment solution. It provides insight to the strategies of how these chemical systems were optimized to stabilize and inhibit the movement of the particulates at their sources, either inside formation matrix, in a gravel pack, or in a proppant pack placed during a frac-pack or other fracture-stimulation treatment. Case histories are provided to support the obtained benefits and advantages. A future direction of chemical technologies for solids-flowback control is also discussed.
In one family of applications, primary approaches included as part of the initial completion, either a curable resin or a noncurable surface-modification agent, have been used to coat the proppant on-the-fly. Globally, these additives were applied in more than 25,000 hydraulic-fracturing treatments, where they were used to enhance and maintain the propped-fracture conductivity. The functions of these coating treatments include ensuring the proppant will stay in place, enhancing its ability to withstand stress cycling, and minimizing migration or invasion of formation sand or fines into the proppant pack. Most recently, these coating methods have been identified to effectively allow the proppant to endure and overcome the degradational effects of diagenesis as the proppant grains are exposed to high closure pressure and high reservoir temperatures, which will hasten the reduction of the fracture conductivity over time.
Another family of applications comprising chemical-consolidation treatments has been applied extensively for the remedial proppant-flowback problems. The treatment methods introduced in the last few years have proven to be reliable, economical, and long lasting, allowing the treated wells to handle higher drawdown with high production flow rates. These proppant remedial treatments drastically decrease the number of workovers when compared to the period before their treatments, or compared to the offset wells in the same field where treatments were not performed. This family of chemical applications provides flexibility, and many are applied as rigless treatments.
Formation sand-consolidation treatments continue to be used in remedial treatments of wells with sand- and fines-production problems, either from open holes, caused by water intrusion, or after failures of sand screens or gravel packs. Although the past treatments were mainly applied in short intervals, efforts are being focused on the development of fluid placement and diversion techniques to extend the length of effectively treated intervals. Also, new treatment-fluid systems are being developed to provide greater ease of application, minimizing compatibility issues between treatment fluids, and minimizing formation damage that can result from a consolidation treatment.
