| 摘要 |
A well screen includes a generally tubular structure 20 having a longitudinal axis 28 and a passage 26 for flow between an interior and an exterior of the well screen. A filter assembly 22 having a restriction to flow which varies in a direction parallel to the longitudinal axis is located around the pipe. The filter section may be made up of discrete sections 30, 32, 34, 36, 38 having different flow properties. The section nearest to the passage where the pressure difference is greatest may have the highest resistance to flow and the section(s) furthest away may have the lowest resistance to flow. In this way the flow and hence erosion along the filter is balanced. |
