Cavern Well Fishing

Cavern Well Fishing

Cavern Well Fishing


    7 days of daylight operations


    Due to regulations, the wellbores of storage caverns must be periodically checked and pressure tested. The customer set a 9-5/8 WR plug in the production casing at 1250m and pressure tested the casing string. The WR plug had been pinned for slickline removal, and slickline was mobilized post pressure test to retrieve the plug. The slickline operation was not able to pull the plug and sheared off, leaving the retrieval tool on the plug. Coil tubing attempted to fish the plug but with no success. Pressure under the WR plug was assumed to be 12mpa.


    The customer contacted Piston Well Service and it was decided that a 142k jack would suffice for this work with a 3 ½ 13.3lb IF drillstring. Spools were added above the 11inch gate valve to house the two fish, then a crossover from 11-5k to 7-10k was installed with Piston BOPs and snubbing unit above.

    Weatherford machined the overshot down to fit through the 7-1/16 stack so that it didn’t require stripping the unit on. Pups were placed in the fishing BHA which were the same length of the stack so the unit could be stripped off of the fish after recovering each piece.

    The BHA included an overshot, floats, a 3-½ bumper sub, 3-½ jars, 6- 3 ½ drillcollars, a 3 ½ intensifier, crossed over to 3 ½ IF and drillpipe to surface. The first run was successful after jarring for 4 hours. The slickline tools came free and they were snubbed out of the well because the WR had started leaking. Once the well was secured, the unit was stripped off and the fish removed. The unit was then re-installed and a retrieving tool was added to the BHA. The string was snubbed to 5m above the fish and the well was forward circulated at 700lpm,until 2 bottoms up were performed and returns were verified to be clean. The WR was latched and after 9 hours of jarring up and bumping down, the WR came free. The string and the fish were snubbed out of the well, and unit was rigged out and de mobilized.