Dual flexible shaft apparatus for improved downhole operations
Systems and a tool are disclosed herein for improved debris collection within a wellbore. An example debris collection tool can include a motor rotationally coupled to a pump by a first flexible shaft, the pump rotationally coupled to a gearbox by a second flexible shaft, and the gear box rotationally coupled to a milling bit by an additional shaft. The flexible shafts can be made of a flexible, but durable material that can absorb strain created by a pump whose rotor rotates eccentrically with the axis of rotation offset from the axis of symmetry. The flexible shafts can be made of a durable and flexible material that can withstand the strain created by the eccentric rotation.
1 . A debris collection tool for debris collection within a wellbore, comprising:
a motor rotationally coupled to a first end of a pump by a first flexible shaft;
a gearbox rotationally coupled to a second end of the pump by a second flexible shaft, wherein the gearbox is configured to modify rotational speed and torque generated by the motor; and
a milling bit rotationally coupled to the gearbox by an additional shaft,
wherein the first and second flexible shafts are separate from the motor, the pump, and the gearbox,
wherein the first and second flexible shafts each comprise a first end portion, a second end portion, and a shaft portion extending between the first and second end portions, and
wherein the first and second end portions of the first and second flexible shafts each comprise a diameter greater than a shaft diameter of the shaft portion.
2 . The debris collection tool of claim 1 , further comprising a bailer positioned between the gearbox and the milling bit, the bailer comprising filters configured to trap debris pulled into the debris collection tool by the pump.
3 . The debris collection tool of claim 2 , further comprising a check valve positioned between the bailer and the milling bit.
4 . The debris collection tool of claim 2 , wherein the pump is configured to receive filtered drilling fluid from the bailer and direct the filtered drilling fluid to exit the debris collection tool and into the wellbore without flowing the drilling fluid through an interior of the debris collection tool.
5 . The debris collection tool of claim 3 , wherein the additional shaft passes through the bailer and the check valve.
6 . The debris collection tool of claim 1 , wherein the motor, when running, simultaneously drives the first flexible shaft at a first speed and a first torque and drives the second flexible shaft at a second speed and a second torque.
7 . The tool of claim 6 , wherein the first speed is faster than the second speed and the first torque is lower than the second torque.
8 . The tool of claim 1 , wherein the second flexible shaft is coupled to a bailer by an adapter that causes the bailer to rotate with the second flexible shaft.
9 . The debris collection tool of claim 1 , wherein a first length of the first flexible shaft and a second length of the second flexible shaft are at least 10 times greater than the shaft diameter of the shaft portion of each of the first flexible shaft and the second flexible shaft.
10 . The debris collection tool of claim 9 , wherein the first length and the second length are at least greater than a length of the gearbox.
11 . The debris collection tool of claim 1 , wherein the second end portion of the first flexible shaft and the first end portion of the second flexible shaft couples to the pump, and the second end portion of the second flexible shaft couples to the gearbox.
12 . A debris collection tool for debris collection within a wellbore, comprising:
a motor rotationally coupled to a first end of a pump by a first flexible shaft; and
a milling bit rotationally coupled to the pump by a second flexible shaft, wherein the second flexible shaft passes through a bailer positioned between the pump and the milling bit without a gearbox positioned between the pump and the milling bit.
13 . The debris collection tool of claim 12 , wherein a rotor of the pump, when the pump is activated, rotates eccentrically with respect to an axis of rotation of the pump being offset from an axis of symmetry of the pump.
14 . The debris collection tool of claim 12 , wherein the pump is a progressive cavity pump.
15 . The debris collection tool of claim 12 , wherein the first flexible shaft and the second flexible shaft comprise titanium, a nickel-titanium alloy, an aluminum alloy, a beryllium-copper alloy, or a cobalt-chromium alloy.
16 . The debris collection tool of claim 12 , wherein the bailer includes filters configured to trap debris pulled into the debris collection tool by the pump.
17 . The debris collection tool of claim 16 , further comprising a check valve positioned between the bailer and the milling bit.
18 . The debris collection tool of claim 12 , wherein the motor is configured to rotationally drive the first flexible shaft at a first speed during milling operations and a second speed during filtering operations.
19 . The debris collection tool of claim 18 , wherein the first speed is slower than the second speed.
20 . The debris collection tool of claim 12 , wherein the second flexible shaft is coupled to the bailer by an adapter that causes the bailer to rotate with the second flexible shaft.