Abstract: A fluid flow switching device for a drill string comprises a tubular member having a port (4). A sleeve member is slidable within the tubular member between a first position in which a port (3) thereof is in alignment with the port (4) and a second position in which the port (4) is obstructed. A plurality of fingers are connected to the sleeve member (2). Each finger defines one segment of a closure member that is closed when the fingers are pivoted inwardly and open when the fingers are pivoted outwardly. An operating surface is positioned within the tubular member, and the fingers are axially slidable thereover as the sleeve member is moved between the first and second positions to close and open the segmented closure.

Abstract: A casing scraper comprises a generally cylindrical body (1) adapted for connection at one end to a drill string, having a plurality of scraping or scouring elements (2) disposed around the outer surface thereof. A pipe (6) extends through the cylindrical body (1). One end of the pipe (6) is adapted for connection to a source of cleaning fluid and the other end is connected to a tail pipe (7). The tail pipe (7) has at least one opening (8) in it through which cleaning fluid may be circulated into the well casing. The casing scraper further comprises filtration structure (4) located above the openings (8) in the tail pipe (7) and remotely operable structure (9, 10) for selectively directing the flow of cleaning fluid from passing outside the filtration structure (4) to passing through the filtration structure (4).

Abstract: A well cleaning tool adapted for connection to a drill string for removing debris and residues from the inner wall of a well casing, comprises an elongate generally cylindrical member (1) having a plurality of scratching elements (2) in the outer surface thereof. First and second helical channels or grooves (3 and 4) are defined in the outer surface of the cylindrical member (1) between the scratching elements (2), the second helical channel or groove (4) running in the counter direction to the first helical channel or groove (3).

Abstract: A casing brush for cleaning the walls of a well casing, the casing brush comprising a body (1) in which are mounted cleaning bristles (2) and an adapter (4) to connect the upper end of the body (1) to the lower end of a bridge plug. The body (1) and the adapter (4) are comprised of a material which is at least drillable by a rock bit.

Abstract: A brush comprises a first body (2) and a second body (1) mounted on the first body (2). The first body (2) has a first set of holes (4) therein and the second body (1) has a second set of through holes (3) therein corresponding in number and spacing to the first set of through holes (4). The first body (2) is moveable relative to the second body (1) between a first position in which each hole (4) in the first set is aligned with a respective hole (3) in the second set to receive therethrough a bristle bundle (5), and a second position in which each pair of holes (3,4) is misaligned to clamp the bristle bundle (4).

Abstract: A casing scraper comprises a generally cylindrical body (1) adapted for connection at one end to a drill string, having a plurality of scraping or scouring elements (2) disposed around the outer surface thereof. A pipe (6) extends through the cylindrical body (1). One end of the pipe (6) is adapted for connection to a source of cleaning fluid and the other end is connected to a tail pipe (7). The tail pipe (7) has at least one opening (8) in it through which cleaning fluid may be circulated into the well casing. The casing scraper further comprises filtration means (4) located above the openings (8) in the tail pipe (7) and remotely operable means (9, 10) for selectively directing the flow of cleaning fluid from passing outside the filtration means (4) to passing through the filtration means (4).