| 摘要 |
A well screen with a filter layer; a cylindrical outer stand-off layer around the filter layer, the cylindrical outer stand-off layer having a construction which is more rigid than a construction of the filter layer; and a collapsible outer cover around the outer stand-off layer, said collapsible outer cover having a construction which is less rigid than the construction of the outer stand-off layer; arranged such that the outer stand-off layer spaces the collapsible outer cover from the filter layer and also resists collapse of the cover towards the filter layer.
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