M-I SWACO declared at the Offshore Europe 2011 Oil and Gas Conference and Exhibition the release of the WELL SCAVENGER* vacuum debris removal tool, which is designed specifically to capture and remove debris from the wellbore during intervention activities.
Wellbore conditions can create inefficient downhole circulation during a debris clean-up operation. After perforating, clean-up can be difficult due to fluid losses that restrict pump rates and pressures. Sensitive pressure-actuated downhole hardware may also limit pump rates and pressures.
Based on a modular design, the WELL SCAVENGER tool comprises a single-nozzle fluid-driving engine, a debris screening module, and one or more debris chambers. The engine module internally generates and maintains an efficient localized reverse circulation flow that achieves maximum lifting velocities without the need for high pump rates from the surface. The debris screening module filters the fluid to capture larger debris and is equipped with an internal magnet assembly to collect ferrous material.
Compared to other tools, the sealed lifting caps of the WELL SCAVENGER tool are significantly safer when handling extracted debris and fluids on the rig floor. The tool can also be combined with string magnets or junk baskets to optimize the removal of ferrous or larger debris.
The tool’s optimum environment is with Newtonian fluids that have limited solids carrying capacity or when open perforations, pressure-sensitive downhole hardware or limitations from surface equipment make it impossible to use high pump rates and pressures.
An operator in Italy’s Adriatic Sea needed to reperforate, gravel pack and return a well to production. Before packer plugs could be retrieved, M-I SWACO recommended the WELL SCAVENGER tool be run to recover intentionally spotted ceramic gravel pack sand and gun debris.
In four runs of the tool, a total 180 lb (82 kg) of debris, comprised of ceramic proppant, gun debris and shear screws from the packer plug, was recovered. All debris was collected with less than one hour of circulating time on each trip. The WELL SCAVENGER tool with two debris chambers picked up sand and perforation debris efficiently, allowing the subsequent retrieval of the zonal isolation plugs to be initiated incident free.
The WELL SCAVENGER tool will enable clean out and retrieval to be completed in one trip by placing the packer plug retrieval tool in the bottom hole assembly (BHA).