Abstract: A magnetic cleaning tool for collecting ferrous debris in a wellbore and a method of cleaning a wellbore. The magnetic cleaning tool has a tool body for attachment in a work string, one or more magnets supported on the tool body, and a sleeve located around the tool body which is arranged to be moveable along the body to provide selective coverage of the magnets. Embodiments are described providing shear pins and spring loaded balls to hold the sleeve either over the magnets or free of the magnets. An expandable piston, moveable by action of a drop ball, is described to release the sleeve. The sleeve is arranged so that the magnets can be covered and therefore effectively inactive on run-in and during downhole operations, and uncovered to be active when pulled out of the wellbore.

Abstract: A downhole mixing tool and method for removing sand and other debris from a wellbore which combines the sand with a treatment fluid so that the sand is lifted to the surface of the well for removal. The tool includes a chamber into which the sand laden fluid is drawn and the treatment fluid is introduced. Ports into the chamber are arranged to provide a pressure drop to draw the sand laden fluid into the chamber and a mixing time within the chamber before sand laden fluid of lower viscosity exits the chamber to travel to the surface. Additional features include blades on the tool for breaking up obstructions prior to being drawn into the chamber and a lubricating line through the tool to introduce lubricating fluid to the blades.

Abstract: A downhole mixing tool and method for removing sand and other debris from a wellbore which combines the sand with a treatment fluid so that the sand is lifted to the surface of the well for removal. The tool includes a chamber into which the sand laden fluid is drawn and the treatment fluid is introduced. Ports into the chamber are arranged to provide a pressure drop to draw the sand laden fluid into the chamber and a mixing time within the chamber before sand laden fluid of lower viscosity exits the chamber to travel to the surface. Additional features include blades on the tool for breaking up obstructions prior to being drawn into the chamber and a lubricating line through the tool to introduce lubricating fluid to the blades.