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Abstract Premature failure of downhole and surface equipment can be caused by the production of formation fines, sand, and/or proppant. This leads to increased production costs associated with frequent workovers to remove fill, replacement of downhole equipment, and surface-equipment overhauls. In addition, production rates are often decreased to minimize solids production and can also compromise ultimate reservoir recovery. Conventional resin-consolidation systems have been successful in preventing solids production in short, homogenous intervals. However, resin consolidation in longer intervals has resulted in erratic success because of the lack of complete and uniform treatment of the entire interval length. Any untreated length of interval has the propensity to produce solids, resulting in a failed treatment. This paper presents the results of laboratory development and field testing of a new water-based resin-consolidation system applicable for proppant flowback and sand consolidation as well as field trials for proppant-flowback applications. This new system benefits from effective and efficient treatment of significantly longer intervals and improved health, safety, security, and environmental compatibility (HSSE) compared to conventional consolidation systems. Introduction Formations that are weakly or poorly consolidated can be plagued by formation-sand production, leading to lost production and, in extreme cases, wellbore failure. Proppant flowback, where proppant is produced out of a hydraulic fracture, might lead to similar results. One solution is to consolidate the near-wellbore region or the propped fracture itself by injecting a curable resin to stabilize the loose material. However, previous generations of resin-consolidation systems suffered from multiple stages for effective treatment, undesirable health and safety fluid concerns from acids and solvents, and difficulties with surface handling and pumping. To address these concerns, a new, aqueous-based consolidation system that is operationally easy to use, has a high flash point, and can be commingled or foamed to extend the treatment volumes has been developed. This new system has now been used to treat wells that have been fracture stimulated with long perforated intervals exceeding 300 ft. Treatment validation was observed using a distributed temperature system (DTS) with thermal tracers (Glasbergen et al. 2007; Glasbergen et al. 2009) to verify that the entire production interval was treated in two of these wells. Post-treatment monitoring has verified that proppant flowback has been stopped and well production was not negatively impacted. New Consolidation Technique Recent developments allow for a dilute concentration of consolidation material to be dispersed in an aqueous-based fluid guided by capillary-driven self-assembly. The challenge was to find products, materials, and processes that would allow a similar technique to be applied for formation sand and proppant packs. A new concept was evaluated where a low concentration (less than 10% by weight) of micron and submicron particles or droplets of consolidating material was dispersed in brine and combined with a low concentration of water-soluble activator. When the formation sand or proppant pack was pretreated with a cationic surfactant, the particles or droplets were attracted to the solid surfaces and specifically attracted to the contact points between grains caused by capillary forces. A scanning electron microscope (SEM) photograph showing these effects is illustrated in Figs. 1 and 2. The result was a surprisingly high-strength consolidated pack achieved using a relatively small amount of the material. |
