Multi-layer screen and downhole completion method

摘要

The invention relates to an expandable filter assembly for downhole use and comprises a base pipe (10) having an inside surface, a plurality of openings (12) and at least one filtration layer (26) mounted over the pipe. A coating (18) is applied to the inside surface of the base pipe (10) to reduce the force required for expansion of the base pipe (10) by an expander (20) (see Fig. 3). The coating (18) may be made from a plastic material such as Xylan (RTM) and the openings (12) may be round or oval in shape. The filtration layer (26) may comprise a weave having angled weft and warp wires. The various layers of the pipe may be annealed to facilitate their subsequent expansion downhole and the filtration and base layers may be swaged together.