The present invention relates to a downhole tool, comprising a hydraulic assembly, an arm assembly, the arm assembly comprising a wheel, a hydraulic motor for rotating the wheel, thereby driving the downhole tool in a forward direction, and a hydraulic pump unit for simultaneous generation of a firs
The present invention relates to a downhole tool, comprising a hydraulic assembly, an arm assembly, the arm assembly comprising a wheel, a hydraulic motor for rotating the wheel, thereby driving the downhole tool in a forward direction, and a hydraulic pump unit for simultaneous generation of a first and a second pressurized fluid, characterized in that the arm assembly is movable between a retracted position and a projecting position in relation to the tool housing, and the downhole tool furthermore comprises an arm activation assembly for moving the arm assembly between the retracted position and the projecting position, and the hydraulic motor drives the downhole tool in the forward direction when the arm assembly is in the projecting position, the arm activation assembly being in fluid connection with the first pressurized fluid and the hydraulic motor being in fluid connection with the second pressurized fluid, a hydraulic control block for controlling the pressure of the first pressurized fluid having a first pressure and controlling a second pressure of the second pressurized fluid, and a hydraulic control block comprising a first sequential valve for controlling a sequence of retraction of the arm assembly, a projection of the arm assembly and a rotation of the wheel, wherein the sequential valve is fluidly connected with one of the fluids and changes between an open and a closed position based upon the pressure of the other fluid. Furthermore, the present invention relates to a method of controlling a projection of an arm assembly of a driving unit of a downhole tool and to a downhole system.
대표청구항▼
1. A downhole tool, comprising: a hydraulic assembly,an arm assembly, the arm assembly comprising a wheel, the arm assembly being movable between a retracted position and a projecting position in relation to a tool housing;a hydraulic motor configured to rotate the wheel, rotation of the wheel being
1. A downhole tool, comprising: a hydraulic assembly,an arm assembly, the arm assembly comprising a wheel, the arm assembly being movable between a retracted position and a projecting position in relation to a tool housing;a hydraulic motor configured to rotate the wheel, rotation of the wheel being adapted to drive the downhole tool within a wellbore downhole;a hydraulic pump unit configured to generate a first pressurized fluid stream at a first pressure and a second pressurized fluid stream at a second pressure, the first pressure being variable compared to the second pressure;an arm activation assembly configured to move the arm assembly between the retracted position and the projecting position, the hydraulic motor being configured to rotate the wheel to drive the downhole tool when the arm assembly is in the projecting position, the arm activation assembly being in fluid connection with the first pressurized fluid stream and the hydraulic motor being in fluid connection with the second pressurized fluid stream;a hydraulic control block adapted to control the pressure of the first pressure and the second pressure; and,the hydraulic control block comprising a sequential valve configured to control a sequence of retraction of the arm assembly, a projection of the arm assembly and a rotation of the wheel;wherein the sequential valve is fluidly connected with one of the fluid streams and changes between an open and a closed position based upon the variable pressure of the other fluid stream. 2. The downhole tool according to claim 1, wherein the first pressurized fluid stream and the second pressurized fluid stream are reunited downstream from the arm activation assembly and the hydraulic motor, respectively, into a downstream fluid entering a hydraulic chamber connected with the hydraulic pump in a closed circuit. 3. The downhole tool according to claim 2, wherein the hydraulic assembly comprises a hydraulic assembly housing being the hydraulic chamber. 4. The downhole tool according to claim 3, wherein the hydraulic block and the hydraulic pump are contained in the hydraulic assembly housing. 5. The downhole tool according to claim 1, wherein the sequential valve is fluidly connected with the second pressurized fluid stream and changes between an open and a closed position based upon the pressure of the first pressurized fluid stream. 6. The downhole tool according to claim 1, wherein the sequential valve is fluidly connected with the first pressurized fluid stream and changes between an open and a closed position based upon the pressure of the second pressurized fluid stream measured upstream of a throttle. 7. The downhole tool according to claim 1, wherein the first pressurized fluid stream is in fluid communication with a direction valve through a pilot connection, the hydraulic motor having first and second inlet ports, the direction valve controlling the second fluid stream entering in the first or the second inlet ports of the hydraulic motor, so that a direction of rotation of the hydraulic motor may be controlled by the first pressurized fluid stream to be in a forward or reverse mode. 8. The downhole tool according to claim 1, wherein the hydraulic control block is configured to rotate the wheel before projection of the arm assembly. 9. The downhole tool according to claim 8, wherein the hydraulic control block is configured to rotate the wheel before the wheel engages a borehole wall or a production casing. 10. The downhole tool according to claim 1, wherein the first pressurized fluid stream exits the hydraulic pump unit at the first pressure, and the second pressurized fluid stream exits the hydraulic pump at the second pressure. 11. A downhole system comprising the downhole tool according to claim 1 and an operational tool connected with the downhole tool for being moved forward in a well or borehole. 12. A method of controlling a projection of an arm assembly of a driving unit of a downhole tool, comprising activation of a hydraulic pump,simultaneous generation of a first pressurized fluid stream having a first pressure and a second pressurized fluid stream having a second pressure, the first pressure being variable compared to the second pressure;activation of a rotation of a hydraulic motor by the first pressurized fluid stream, which in turn drives a wheel of the arm assembly,increasing the first pressure until the first pressure reaches a predetermined projection pressure;activating an arm activation assembly by a first sequential valve; andactivating a projection of the arm assembly by the second pressure of the second pressurized fluid stream. 13. The method according to claim 12, further comprising: forcing the second pressurized fluid stream through an orifice and into a first sequential valve, thereby gradually closing the first sequential valve and replacing the step of activation of an arm activation assembly by the first sequential valve;increasing the second pressure upstream of the orifice;gradually closing a second sequential valve by increasing the second pressure of the second pressurized fluid stream;increasing the first pressure of the first pressurized fluid stream, replacing the step of increasing the first pressure until the first pressure reaches a predetermined projection pressure;increasing the second pressure further when the wheel of the arm assembly abuts an inner wall of the borehole or production casing;closing the second sequential valve by the second pressure; further increasing the first pressure of the first pressurized fluid stream until a maximum pressure of the first pressure of the first pressurized fluid stream is obtained; and driving a tool string in a forward direction. 14. The method according to claim 12, wherein the activation of the projection of the arm assembly occurs when the pressure of the second pressurized fluid stream surmounts a spring force applied to the arm activation assembly by a spring member. 15. The method according to claim 12, further comprising deactivation of a hydraulic pump;deactivation of a projection of the arm assembly by a decrease of the second pressure of the second pressurized fluid stream;decreasing the second pressure until the arm assembly is retracted; anddecreasing a rotation of a hydraulic motor by decreasing the first pressure of the first pressurized fluid stream driving a wheel of the arm assembly in which the hydraulic motor is arranged. 16. The method according to claim 15, wherein the activation of the retraction of the arm assembly occurs when the pressure of the second pressurized fluid stream becomes inferior to a spring force applied to the arm activation assembly by a spring member. 17. The method according to claim 12, further comprising: driving the downhole tool in a forward direction;deactivation of the hydraulic pump;deactivation of the projection of the arm assembly by decreasing the second pressure of the second pressurized fluid stream;decreasing the second pressure until the arm assembly is retracted; anddecreasing the rotation of the hydraulic motor by decreasing the first pressure of the first pressurized fluid stream. 18. The method according to claim 12, further comprising: activation of an arm activation assembly by the second pressurized fluid stream instead of by a first sequential valve;increasing the second pressure when a wheel of the arm assembly abuts an inner wall of the borehole or production casing, replacing the step of increasing the first pressure until the first pressure reaches a predetermined projection pressure; andincreasing the second pressure until the second pressure reaches a predetermined rotation pressure; wherein the step of activation of a rotation of a hydraulic motor by the first pressurized fluid stream for driving the wheel of the arm assembly is performed by a first sequential valve, driving the downhole tool in a forward direction;deactivation of the hydraulic pump;decreasing the rotation of the hydraulic motor by decreasing the first pressure of the first pressurized fluid stream;deactivation of a projection of the arm assembly by decreasing the second pressure of the second pressurized fluid stream; anddecreasing the second pressure until the arm assembly is retracted. 19. The method according to claim 12, wherein the first pressurized fluid stream is configured to rotate the wheel before the second pressurized fluid stream projects the arm assembly. 20. The method according to claim 19, wherein the first pressurized fluid stream is configured to rotate the wheel before the wheel engages a borehole wall or a production casing.
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이 특허에 인용된 특허 (1)
Gissler Robert W. ; Holcombe Michael W. ; Purkis Daniel,GBX, Downhole tractor.
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