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Abstract Packing the annulus and perforations with gravel in highly deviated wells, especially horizontal wells, is difficult. As well deviation increases, pump rates and carrier fluid viscosities increase to prevent particle settling. Increasing the viscosity can reduce fluid leakoff and particle settling. Increasing the viscosity can reduce fluid leakoff and perforation pack efficiency. Gravel-pack studies have shown that placement perforation pack efficiency. Gravel-pack studies have shown that placement efficiency improves as particle density (Dp) and carrier fluid density (Dc) become closer. in an ideal system, these densities would be equal (Dp:Dc = 1). With this ideal design, no viscosity would be required to suspend the particles, thereby improving fluid leakoff and perforation packing. The use of sand as the packing material has limited the use of packing. The use of sand as the packing material has limited the use of such a technique because of hydrostatic overbalance. The introduction of a pack material whose density (1.65 g/cc) is 40% less than that of pack material whose density (1.65 g/cc) is 40% less than that of sand makes this technique available without the overbalance concerns. The paper provides the industry with technology which is applicable when gravel packing highly deviated (horizontal) wells. This paper describes:a new method of completing highly deviated and horizontal wells using low density particles and low Dp:Dc ratios,computer simulations performed to aid in designing completion techniques,printouts of the screenout pressure and pump rates,schematics of the well design,logs of the pack andwell performance. performance Introduction Gravel packing a highly deviated well using conventional products and completion techniques can be extremely difficult. In highly deviated wells, prepack screens are used, as an insurance step, in case the perforated interval is not completely covered. The prepack screen adds perforated interval is not completely covered. The prepack screen adds additional cost and may restrict production due to plugging by fine particles. ideally, nothing would change between a conventional pack and a particles. ideally, nothing would change between a conventional pack and a highly deviated pack. However, because of gravitational forces, alterations in the completion are required to successfully complete the well. This paper describes the successful gravel-packing operation on a 72 degree deviated well using a low-density particle (LDP) and standard gravel-pack screen in the Gulf of Mexico. The well is located approximately 135 miles (217 km) offshore from Cameron, Louisiana, in 175 ft (53 m) of water. The objective pays of the well are at 2,200 to 2,900 ft (671 to 884 m) subsea and located under a shipping fairway. To drill these upper and lower sands, the well had to be kicked off at the mudline and drilled at an average angle of 72 degrees with the surface location 300 ft (91 m) from the fairway and the bottomhole location 6,533 ft (1991 m) into the fairway (Fig. 1). The casing profile initially called for a 7-5/8-in. (194-mm) Uner, but because of excessive wear in the 10-3/4-in. (273-mm) casing, the liner was tied back to surface. The open-hole logs were obtained with a logging while drilling tool on the end of the drillpipe. All cased hole logs were run on coiled tubing electric line. This is 1-1/2-in (36-mm) coiled tubing with a multiconductor electric line through it. Gravel packing the annulus and perforations in highly deviated wells and especially horizontal wells is difficult. Gruesbeck et al. determined packing efficiency increases with- lower gravel concentrations, decreasing particle diameter, decreasing particle density, increasing fluid density, increasing pump rate, and increasing resistance to fluid flow in the washpipe/screen annulus. Shyrock found that in addition to the above parameters, reducing the length of blank sections In the screen and reducing the fluid viscosity increase packing efficiency. P. 387 |
