What! No Screen? Gravel Packing With Water-Carried Resin Coated Gravel

Abstract Significant improvements in resin coated gravel packing have been developed in a new water-carried system. These improvements are aqueous carrying fluids with a specially formulated epoxy resin. Consolidated gravel packs formed by this system are strong and highly permeable and do not require a screen or liner for successful sand control. Sand control treatments can now be performed in intervals separated by no more than fifteen feet without any loss of natural permeability. Field results from over 100 wells treated with this system have shown it to be easily performed and effective in a wide variety of well conditions. Laboratory development and field results are discussed. INTRODUCTION Sand control methods utilizing high solids content slurries of epoxy resin coated gravel have become an effective and popular technique. The strong. highly permeable sand filters formed by these processes control sand without the use of a screen and retain their effectiveness over long periods of time. The basic process involves coating specially sized gravel with a resin which is suspended in a thick carrying fluid. The slurry is then pumped into the well and squeezed out of the perforations until a sand-out occurs. After the resin cures and consolidates the sand pack. the wellbore is drilled out and the well returned to production (Figure 1). The techniques and materials used in this method of sand control have changed and improved in recent years in response to industry needs. The first commercially successful system of this type utilized hydrocarbon flushes and carried the resin coated gravel in an oil slurry.1 This system was effective in controlling sand but had disadvantages associated with the oil and hydrocarbon flushes. Some of these disadvantages were pollution hazard, high friction pressure, cost and availability. Also. careful quality control of the oil was necessary since the presence of cationic contaminants could interfere with the resin coating of the sand grains resulting in low strength consolidated sand packs and the risk of formation damage due to resin suspended in the carrying fluid.2 A more recently reported system employs an epoxy emulsion and thickened brine carrying fluid to prepare the resin coated gravel slurry.3 The use of aqueous fluids gave this system several advantages in terms of costs, pollution, and fluid rheology but also caused problems in terms of placement of the resin on the sand grain surface. The emulsified resin system and the use of the water soluble amine which acted as both coupling agent and curing agent resulted in a difficult mixing procedure and rather low compressive strengths in the consolidated packs (700–1100 psi). Also. after the gravel had been coated with resin, a wash step was necessary to remove excess resin not on the gravel surface. This step was necessary to prevent possible formation damage by resin suspended in the carrying fluid. The process described in this paper is an improved resin coated gravel packing system which is carried by a thickened brine carrying fluid and utilizes all aqueous flushes. This process has the advantages associated with aqueous fluids such as low friction pressure, low pollution hazard and safer handling. but is unique in that the carrying fluid and resin systems are designed to allow the resin to efficiently coat the gravel and leave very little resin suspended in the carrying fluid. The resultant consolidated sand packs are strong and permeable and there is minimal risk of permeability damage to the formation. This type of sand control technique has been found to be particularly applicable as a primary sand control method in wells with relatively short intervals (generally less than 20 feet), in formations with high clay contents (>20%), and in multiple completions where the interval spacings preclude the use of screens.