| 摘要 |
PROBLEM TO BE SOLVED: To prevent sand pumping without spoiling water pumping capacity in spite of existence of sand pumping in a well using a pipe base screen by the optimum modifying engineering method. SOLUTION: A newly provided casing string 11 having a V slot screen 10 is inserted in an existing casing string 8 and both of the screens 7, 10 are made to face against each other under this modifying method of a well. Ballast 12 is filled to a position higher than a still water level in a ring clearance A of the existing and newly provided casing strings 8, 11. Thereafter, finishing by partial surging is carried out in the V slot screen 10, the filled ballast 12 is made to flow in an aquifer 13 from a round hole of a pipe base 3 and filled, a ballast wall is made thicker, sand pumping is prevented, and water pumping capacity is increased.
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