Downhole surge tools

Downhole surge tool for completion and/or reworking of fluid-bearing wells, adapted to connection with the downhole end of a dry tubing string, the tool being actuated to provide an instantaneous full opening into the tubing of surging fluids and particulate matter inwardly from the formation and upwardly into the tubing. The downhole surge tool is characterized by its non-jammable assemblage, wherein its surge plug may not be completely reinserted upon the influence of a powerful or overwhelming backsurge. The tool includes a tubular nipple, ejectable surge plug, operably inserted into the nipple and an optional catcher sub, the plug including a positive ejection assembly which is actuated upon partial ejection of the plug, permitting limited re-entry only of the plug into the nipple. A seal is provided between the plug and the nipple, the seal being disposed above pressure relief ports within the surge plug. The positive ejection assembly of the plug includes two horizontally disposed pistons which are housed in opposed relationship within the lower end of the plug, the plug being seated and sealed within the nipple. The pistons being compressed against the inner surface of the nipple, a shearpin is installed to pass through the nipple walls and piston assembly.