Ellingson-DTD installed one single-ended (blind) coal ash dewatering well within a partially closed CCR basin. The basin contained both flue gas desulfurization (FGD) waste and fly ash. The well was constructed utilizing the Knock Off (KO) well completion technology.
In this drilling/installation method, we used steel, drillable casing to advance a pre-planned bore path to an underground termination point. Upon reaching the end of the bore, the crew pushed the well material down through the center of the casing. When the well material reached the end, it latched onto and pushed the sacrificial drill bit off the drill string. The drillable casing was then tripped out of the bore, leaving the well in place.
This method allows us to install long single-ended wells in unconsolidated ash that may not allow an open-bore installation approach. The bore path was navigated utilizing walkover navigation methods. Well materials consisted of a 4” diameter, schedule 80, flush threaded PVC screen and blank riser. The final screen length is 1,000’ in length, completed about 67’ below the entry point. The total installed length of the well is 1,350’.
Biodegradable drilling fluid was used for drilling and well installation. Well development consisted of flushing and jetting with an enzyme breaker solution and overpumping with a submersible pump. Ellingson crews also completed a variable rate and long-term drawdown test. The results of the pump testing indicate that the yield of the well is approximately 11.5 gallons per minute (gpm).
