Controlling Sand With an Epoxy-Coated, High-Solids-Content Gravel Slurry
Authors: Copeland C.T. , McAuley J.D. 
Published: December 2007

A new sand control process, effective in either old or new wells, has been applied successfully in more than 600 wells in Louisiana and Texas. Here are a review of field results and an outline of some important aspects of treatment design such as batch size, pump rate, gravel size, positioning of down-hole equipment, and the pumping sequence of fluids and slurry.

Introduction

The current emphasis on disaster prevention in offshore wells combined with the need to produce all wells at their maximum efficient rate has increased the need for effective sand control systems that do not cause impairment. A longstanding problem has been that of controlling sand in wells producing sizable quantities of it. In the past, two of the most widely used sand control methods have been gravel packing and in-situ sand consolidation. Although both methods have enjoyed considerable success, they have not always been as effective as desired. Neither method has proved effective more than half the time in treating old wells. The desire for a sand control method that would have the advantages of gravel packing without the susceptibility to shifting has led to the development of a number of processes that call for placing resincoated gravel across the producing interval. Essentially, the gravel is coated with resin at the surface and is carried into place in the well by a carrying fluid; then the resin either is allowed to cure or is flushed with a catalyst solution to effect cure.

The Process

In this process the gravel is placed as a concentrated slurry in a viscous carrying oil. Either of two internally catalyzed epoxy resin formulations is used to lightly coat the gravel. The slurry of resin-coated gravel is squeezed out be perforations until a screenout occurs or, in some cases, until a predetermined amount of slurry has been placed. In either case, the squeezing of the slurry is usually stopped while there is still enough slurry in the casing to leave a cap of the gravel in the casing above the perforations. In some cases where no screen-out is obtained, several barrels of excess slurry is squeezed and another batch of slurry is pumped into the well. After curing, the resin-coated gravel left inside the casing is drilled out, and the well is returned to production. At the writing of this paper, the new process has been applied in more than 600 treatments. The treated wells generally have been oil wells with perforated intervals ranging in length from 2 to 31 perforated intervals ranging in length from 2 to 31 ft. A few treatments have also been performed in gas wells and water injection wells. All but two of the treatments have been in cased and perforated intervals. One of the two noncased holes treated was a California well in which a slotted liner had failed. The liner was perforated in the area where sand was being produced, and two 10-bbl batches of slurry were pumped produced, and two 10-bbl batches of slurry were pumped to repair the screen. After the treatment, sand-free production was obtained. production was obtained. The treatment results in general have been very encouraging. Between 80 and 90 percent success has been obtained in treating both old and new wells. Naturally, changes in procedure have evolved since the method was first introduced to the field in late 1971.

JPT

P. 1215