| 摘要 |
<p>A downhole filter (10) comprises a tubular member having a wall defining a plurality of openings (16). The openings have an outer width (Wo) less than an inner width (Wi). The parts of the opening defining the smaller width are defined by radially outer parts of the openings, such that particulates or sand prevented from passing through the openings will tend to be retained to the outside of the tubular member. <IMAGE></p> |
