Abstract: A casing drilling system includes combination conduit of a casing and a pipe inside the casing. A first adapter has a flow diverter to redirect at least flow of drilling fluid returning from a bottom of a wellbore to either an interior of the pipe or an annular space between the casing and the pipe. A second adapter has a flow diverter to redirect flow of drilling fluid into the conduit through the other one of the interior of the pipe and the annular space. The second adapter has a fluid connection between either the interior of the pipe or the annular space and a rotationally fixed fluid outlet. The system includes a casing chuck having means to support the casing and a slidable conduit operable to expose an uppermost end of the casing and a connection between the second adapter and an uppermost end of the pipe.

Abstract: A casing drilling system includes combination conduit of a casing and a pipe inside the casing. A first adapter has a flow diverter to redirect at least flow of drilling fluid returning from a bottom of a wellbore to either an interior of the pipe or an annular space between the casing and the pipe. A second adapter has a flow diverter to redirect flow of drilling fluid into the conduit through the other one of the interior of the pipe and the annular space. The second adapter has a fluid connection between either the interior of the pipe or the annular space and a rotationally fixed fluid outlet. The system includes a casing chuck having means to support the casing and a slidable conduit operable to expose an uppermost end of the casing and a connection between the second adapter and an uppermost end of the pipe.

Abstract: A mud lift pump for a dual drill string includes an energy input and an energy output in fluid communication with a fluid return flow passage in the dual drill string.

Abstract: A drilling method includes arranging a dual drill string (20) having an inlet fluid conduit (9) and a return fluid conduit (10) in a well (14) formed in a subsurface formation such that a well annulus (22) is formed between the dual drill string (20) and a wall (21) of the well (14). A divider element (3) is disposed in the well annulus (22) to divide the well annulus (22) into an upper annular region (5) extending above the divider element (3) to a surface of the well annulus (22) and a lower annular region (12) extending below the divider element (3) towards a bottom of the well annulus (22). The lower annular region (12) contains a first fluid (25). A second fluid (27) is fed into the upper annular region (5). The method includes configuring the second fluid such that the density of the second fluid (27) is greater than the density of the first fluid (25).

Abstract: The present invention regards a valve device for use with a down hole tool comprising at least a first fluid line and a return fluid line, the valve device comprises a first inlet and a first outlet forming a first flow path between them, and a second inlet and a second outlet forming a second flow path between them, at least one closure element for closing and or opening at least one of the flow paths. According to the invention there is at least one closure element together with the respective flow paths forms a first and second check valves, which in a first state prevents a fluid from flowing from the first outlet to the first inlet and a fluid from flowing from the second inlet to the second outlet. The invention also regards a method for operating a down hole valve device.

Abstract: The invention concerns a unit for a down hole well tool comprising a tool unit comprising at least one first fluid conduit and a return fluid conduit in use forming a well annulus space between the tool unit and the well bore. The tool unit is arranged with at least one piston provided for dividing the well annulus space into at least two well annulus spaces. The communication of fluid between the adjacent well annulus spaces at each side of the piston is controlled by the relative movement between the first fluid conduit and a control element.

Abstract: The present invention relates to a method for cleaning and possibly sealing a subsurface well. According to the method a multichannel tool string comprising an adapter on a first end of the tool string, a guide device at the second end of the tool string are run into the well, whereupon the guide device is activated in order to permit the well to be flushed by the supply of fluid through at least one of the channels in connection with the tool string and fluids and particles from the well are transported back to the surface through at least one other of the channels in connection with the tool string. The invention also relates to a device for cleaning and possibly sealing a subsurface well.

Abstract: The invention concerns a unit for a down hole well tool comprising a tool unit comprising at least one first fluid conduit and a return fluid conduit in use forming a well annulus space between the tool unit and the well bore. The tool unit is arranged with at least one piston provided for dividing the well annulus space into at least two well annulus spaces. The communication of fluid between the adjacent well annulus spaces at each side of the piston is controlled by the relative movement between the first fluid conduit and a control element.

Abstract: The present invention regards a valve device for use with a down hole tool comprising at least a first fluid line and a return fluid line, the valve device comprises a first inlet and a first outlet forming a first flow path between them, and a second inlet and a second outlet forming a second flow path between them, at least one closure element for closing and or opening at least one of the flow paths. According to the invention there is at least one closure element together with the respective flow paths forms a first and second check valves, which in a first state prevents a fluid from flowing from the first outlet to the first inlet and a fluid from flowing from the second inlet to the second outlet. The invention also regards a method for operating a down hole valve device.

Abstract: The present invention relates to a method for cleaning and possibly sealing a subsurface well. According to the method a multichannel tool string comprising an adapter on a first end of the tool string, a guide device at the second end of the tool string are run into the well, whereupon the guide device is activated in order to permit the well to be flushed by the supply of fluid through at least one of the channels in connection with the tool string and fluids and particles from the well are transported back to the surface through at least one other of the channels in connection with the tool string. The invention also relates to a device for cleaning and possibly sealing a subsurface well.

Abstract: A device for drilling holes (1) in the crust of the earth, especially for drilling oil wells, wherein a rotary bit (2) is fitted in a drill string (4), within which drilling fluid is pumped downwardly and, upon return, conveys cuttings to the surface. A piston (5) is mounted on the drill string (4) above the bit (2) and adapted to form a sliding seal against the wall of the hole (1). A seal (8) is mounted above the piston (5) within the hole (1) and adapted to seal against the wall of the hole (1), against the drill string (4), against a return line (6) adapted to conduct drilling fluid with cuttings from the under side of the piston (5) to the top of the seal (8), as well as against a pipe (9) communicating with a pump (10) adapted to pump liquid in between the seal (8) and the piston (5), whereby liquid pressure acting against the upper face of the piston (5) urges the bit (2) against the bottom of the hole (1).