Downhole well cleaning tool
View Patent ↗A downhole well cleaning tool adapted for connection between upper and lower sections of an elongate string includes a pump barrel having at least one fluid outlet proximate its upper end. A swab assembly is connected to a pump mandrel for reciprocation within the pump barrel to pump fluids upward to the outlet to draw fluid and debris into the lower string section and trap the debris. A lower portion of the swab mandrel is hollow and open at a lower end thereof with at least one conduit extending through a side wall of the swab mandrel to direct fluid laterally outward from the hollow lower portion against the side wall of the pump barrel during lowering into fluid to reduce debris build-up within the pump barrel. A wear bushing is mounted between the pump mandrel and barrel and a knuckle or swivel joint connects the swab and pump mandrels.
1. A downhole well cleaning tool adapted for connection between upper sections and a hollow lower section of an elongate string extendable down into a wellbore lower section first, the lower section comprising an inlet spaced from an end of the lower section nearest the upper sections and equipped with a check valve to selectively open and close the inlet and the upper section being connectable to a drive source operable to reciprocate the upper sections along the wellbore, the clean out tool comprising:
an elongate tubular pump barrel connectable at a lower end thereof in fluid communication with the hollow lower section of the elongate string and having at least one fluid outlet through a side wall near of the pump barrel proximate an upper end thereof,
an elongate pump mandrel connectable at an upper end thereof to the upper sections of the elongate string and extending through the upper end of the pump barrel, the pump mandrel and the pump barrel being arranged to allow reciprocal motion of the pump mandrel relative to and along the pump barrel while preventing relation rotation between the pump barrel and the pump mandrel; and
a swab assembly connected at an upper end thereof to a lower end of the pump mandrel and reciprocally contained within the pump barrel, the swab assembly comprising a swab mandrel having at least one longitudinal bypass channel extending therealong and a swab cup disposed about and slidable along the swab mandrel between upper and lower stops defined thereon to limit sliding motion of the swab between uppermost and lowermost positions in which fluid flow from one side of the swab cup to an opposite side thereof through the bypass channel is allowed and prevented respectively, the swab cup sealing against an interior of the side wall of the pump barrel in the lowermost position to seal off fluid flow from the one side of the swab cup to the opposite side thereof between the swab cup and the side wall of the pump barrel;
a lower portion of the swab mandrel being hollow and open at a lower end thereof, at least one conduit extending through a side wall of the swab mandrel to communicate an interior of the hollow lower portion thereof with an exterior thereof to direct fluid laterally outward from the interior of the hollow lower portion of the swab mandrel against the side wall of the pump barrel during lowering of the swab mandrel into fluid within the pump barrel.
2. The downhole well cleaning tool according to claim 1 wherein the at least one conduit extending through the side wall of the swab mandrel is angled obliquely upward from the interior of the hollow lower portion relative to a longitudinal axis of the swab mandrel.
3. The downhole well cleaning tool according to claim 1 wherein the at least one conduit comprises a plurality of conduits opening at an outer surface of the side wall of the swab mandrel at locations spaced about the periphery thereof.
4. The downhole well cleaning tool according to claim 1 wherein each conduit is smaller in diameter than the interior of the hollow lower portion of the swab mandrel.
5. The downhole well cleaning tool according to claim 1 wherein the interior of the hollow lower portion of the swab mandrel flares outwardly toward a lower end of the swab mandrel to define a maximum diameter of the interior at an inlet thereof.
6. The downhole well cleaning tool according to claim 1 comprising a movable joint connecting the pump mandrel and the swab mandrel to allow movement of the swab mandrel into and out of alignment with a longitudinal axis of the pump mandrel.
7. The downhole well cleaning tool according to claim 1 wherein the swab mandrel is connected to the to the pump mandrel by a knuckle or swivel joint.
8. The downhole well cleaning tool according to claim 1 further comprising a wear bushing mounted to the pump mandrel at a position therealong.
9. The downhole well cleaning tool according to claim 8 wherein the wear bushing is positioned proximate the lower end of the pump mandrel.
10. The downhole well cleaning tool according to claim 8 wherein the wear bushing has at least one passage extending from one side of the wear bushing to an opposite side of the wear bushing along the pump mandrel to allow fluid flow upward past the wear bushing.
11. The downhole well cleaning tool according to according to claim 10 wherein the at least one passage of the wear bushing comprises at least one groove in an outer periphery of the wear bushing.
12. The downhole well cleaning tool according to according to claim 8 wherein the wear bushing comprises a brass bushing.
13. The downhole well cleaning tool according to claim 1 wherein the pump mandrel and an opening in the closed upper end of the pump barrel each have a straight-sided cross-sectional shape.
14. The downhole well cleaning tool according to claim 1 further comprising a drive sub connecting the pump mandrel and the upper sections of the elongate string, the drive sub receiving the upper end of the pump mandrel in a hollow receiving end of the drive sub and having holes projecting from a periphery of the drive sub into the hollow receiving end to receive set screws for engagement thereof with the pump mandrel proximate the upper end thereof.
15. The downhole well cleaning tool according to claim 14 wherein the pump mandrel comprises recesses in a periphery thereof proximate the upper end of the pump mandrel at spaced positions thereabout to receive engagement ends of the set screws.
16. The downhole well cleaning tool according to claim 1 wherein each longitudinal bypass channel is defined at the periphery of the swab mandrel, fluid flow along each longitudinal bypass delivering fluid through a central opening in the swab cup between the swab cup and the swab mandrel.
17. The downhole well cleaning tool according to claim 16 wherein the swab mandrel is cruciform in cross section, thereby defining four longitudinal bypasses.
18. The downhole well cleaning tool according to claim 1 in combination with the lower section of the elongate string, the check valve of the lower section comprising a ball check valve.
19. A downhole well cleaning tool adapted for connection between upper sections and a hollow lower section of an elongate string extendable down into a wellbore lower section first, the lower section comprising an inlet spaced from an end of the lower section nearest the upper sections and equipped with a check valve to selectively open and close the inlet and the upper section being connectable to a drive source operable to reciprocate the upper sections along the wellbore, the clean out tool comprising:
an elongate tubular pump barrel connectable at a lower end thereof in fluid communication with the hollow lower section of the elongate string and having at least one fluid outlet through a side wall near of the pump barrel proximate an upper end thereof,
an elongate pump mandrel connectable at an upper end thereof to the upper sections of the elongate string and extending through the upper end of the pump barrel, the pump mandrel and the pump barrel being arranged to allow reciprocal motion of the pump mandrel relative to and along the pump barrel while preventing relation rotation between the pump barrel and the pump mandrel;
a swab assembly connected at an upper end thereof to a lower end of the pump mandrel and reciprocally contained within the pump barrel, the swab assembly comprising a swab mandrel having at least one longitudinal bypass channel extending therealong and a swab cup disposed about and slidable along the swab mandrel between upper and lower stops defined thereon to limit sliding motion of the swab between uppermost and lowermost positions in which fluid flow from one side of the swab cup to an opposite side thereof through the bypass channel is allowed and prevented respectively, the swab cup sealing against an interior of the side wall of the pump barrel in the lowermost position to seal off fluid flow from the one side of the swab cup to the opposite side thereof between the swab cup and the side wall of the pump barrel; and
a wear bushing mounted to the pump mandrel at a position therealong and having at least one passage extending from one side of the wear bushing to an opposite side of the wear bushing along the pump mandrel to allow fluid flow upward past the wear bushing.
20. A downhole well cleaning tool adapted for connection between upper sections and a hollow lower section of an elongate string extendable down into a wellbore lower section first, the lower section comprising an inlet spaced from an end of the lower section nearest the upper sections and equipped with a check valve to selectively open and close the inlet and the upper section being connectable to a drive source operable to reciprocate the upper sections along the wellbore, the clean out tool comprising:
an elongate tubular pump barrel connectable at a lower end thereof in fluid communication with the hollow lower section of the elongate string and having at least one fluid outlet through a side wall near of the pump barrel proximate an upper end thereof,
an elongate pump mandrel connectable at an upper end thereof to the upper sections of the elongate string and extending through the upper end of the pump barrel, the pump mandrel and the pump barrel being arranged to allow reciprocal motion of the pump mandrel relative to and along the pump barrel while preventing relation rotation between the pump barrel and the pump mandrel;
a swab assembly connected at an upper end thereof to a lower end of the pump mandrel and reciprocally contained within the pump barrel, the swab assembly comprising a swab mandrel having at least one longitudinal bypass channel extending therealong and a swab cup disposed about and slidable along the swab mandrel between upper and lower stops defined thereon to limit sliding motion of the swab between uppermost and lowermost positions in which fluid flow from one side of the swab cup to an opposite side thereof through the bypass channel is allowed and prevented respectively, the swab cup sealing against an interior of the side wall of the pump barrel in the lowermost position to seal off fluid flow from the one side of the swab cup to the opposite side thereof between the swab cup and the side wall of the pump barrel; and
a movable joint connecting the pump mandrel and the swab mandrel to allow movement of the swab mandrel into and out of alignment with a longitudinal axis of the pump mandrel.