Downhole device
The invention relates to a downhole device for incorporation into a downhole string and movement in a wellbore. The device comprises a body member, at least one roller arranged on the device to engage the inner surface of the wellbore and means to orient the device in the wellbore. The means to orient the device are provided on the or each roller. Preferably the means to orient the device comprise a projecting portion provided on the or each roller which projects radially outwardly from the body member. The projecting portion can be an eccentrically-shaped portion of the or each roller.
1. A downhole device for incorporation into a downhole string and movement in a well-bore, the device comprising:
a body member having a central longitudinal axis;
at least one roller arranged on the device to engage an inner surface of the well-bore, the at least one roller comprising a running edge extending around an outer circumference of the roller and a portion configured to orient the device in the wellbore, the roller having a rotational axis perpendicular to and extending through the central longitudinal axis of the body member and perpendicular to the circumferential running edge, the roller being mounted on the device so as to permit the roller to rotate about its rotational axis relative to the body member; and
wherein the portion of the roller configured to orient the device comprises a projecting portion of the roller which projects radially outwardly from the body member in a direction of the rotation axis of the roller, the projecting portion of the roller is shaped such that the projecting portion of the roller is eccentric to the body member.
2. A downhole device according to claim 1 , wherein a dimension of the roller along the axis of rotation of the roller is larger than a radial distance of the roller perpendicular to the axis of rotation.
3. A downhole device according to claim 1 , wherein the eccentrically shaped portion comprises an oval shape which extends from an outer diameter of the roller to an end of the projecting portion.
4. A downhole device according to claim 1 , wherein the portion of the roller configured to orient the device is provided by the roller being offset from the central longitudinal axis of the device such that the roller projects from the body of the device in the direction of the axis of rotation of the roller.
5. A downhole device according to claim 1 , wherein the running edge is shaped such that it matches the inner surface of the well bore in which the device is to be run.
6. A downhole device according to claim 1 , wherein the roller is secured to the device via a pin which provides the axis of rotation about which the roller may rotate.
7. A downhole device according to claim 1 , wherein the roller is provided with a rotational friction reducing mechanism adapted to reduce frictional forces created when the roller rotates about the axis of rotation.
8. A downhole device according to claim 7 , wherein the friction reducing mechanism comprises a roller bearing arrangement adapted to act between the portion of the roller and a portion of the pin.
9. A downhole device according to claim 7 , wherein the friction reducing mechanism comprises a slip surface provided on the portion of the roller in abutment with a slip surface provided on a portion of the body member of the device.
10. A downhole device according to claim 9 , wherein the friction reducing mechanism provides the axis of rotation about which the roller is rotatable.
11. A downhole device according to claim 10 , wherein the slip surface comprises a durable low friction material.
12. A downhole device according to claim 9 , wherein the slip surface comprises a durable low friction material.
13. A downhole device according to claim 1 , wherein a plurality of rollers are provided on opposing sides of the device.
14. A downhole device according to claim 13 , wherein the plurality of rollers are alternately spaced on opposing sides along the length of the device.
15. A downhole device according to claim 1 , wherein the roller is provided in a recess provided in the body member of the device.
16. A downhole device according to claim 1 , wherein the device has at least one swivel device arranged to allow rotation of the body member.
17. A downhole device according to claim 1 , wherein a throughbore capable of housing at least one elongate member is provided within the body member of the device.
18. A downhole device for incorporation into a downhole string and movement in a well-bore, the device comprising:
a body member having a central longitudinal axis;
at least one roller arranged mounted to the body member and configured to engage an inner surface of the well-bore, the at least one roller comprising a running edge extending around an outer circumference of the roller and a portion configured to orient the device in the wellbore, the roller having a rotational axis perpendicular to and extending through the central longitudinal axis of the body member and perpendicular to the circumferential running edge, the roller being mounted on the device so as to permit the roller to rotate about its rotational axis relative to the body member, the roller mounted to the member such that the portion of the roller configured to orient the device is eccentric to the body member.