Patent ID: 7891419

Claim:
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.