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 tool comprises a tubular body (12) for location in a tubular member, such as a drill string, and defines a through bore (20) and a number of circumferentially spaced ports (26). A valve member which may be in the form of a piston sleeve (24) is mounted in the bore (20) and is movable relative to the body (12) between a first position in which fluid may flow through the port (26) and a second position in which the valve member (24) closes the port (26), the valve member being movable between the first and second positions by application of differential fluid pressure. Movement of the valve member (24) is provided by a cam arrangement including a circumferentially extending cam groove (56) and a cam follower (57).

Abstract: A 2-stage underreamer for use in a subterranean wellbore includes a unitary body having upper and lower blades mounted in slots formed perpendicular to each other in the body. Separate upper and lower piston assemblies are provided for driving the blades respectively from a storage configuration in which they are located substantially completely within the slots to a use position. The blades each include a steel arm having mounted thereon a base of tungsten nickel cobalt matrix in which diamond and/or tungsten carbide inserts are provided. A signal is given to the surface that the blades are in their extended position by changing the mud.

Abstract: A tool for the cleaning and conditioning of tubular structures, such as well casings, comprises a central mandrel (1) upon which are mounted a plurality of interchangeable sleeves (4-9). The sleeves at each end bear stabilization elements enabling the tool to be used in a well casing of any disposition and the intermediate sleeves bear conditioning or cleaning elements (12) angularly spaced apart and separated by fluid channels (13), the cleaning elements of adjacent sleeves being off-set to form a substantially helical pattern of cleaning elements and channels to ensure 360.degree. of coverage as a tool is axially displaced within a well casing. The sleeves are mounted in such a way that relative rotation between them and the mandrel is prevented by a combination of keyways and of drive faces between adjacent sleeves formed by cut-away portions.

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.