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A caliper tool used on a drilling tubular and having extensible members that remain decoupled with respect to the borehole wall during caliper measurements and while the extensible members are extended to allow movement in and through the borehole. A processor processes known and measured informatio

A caliper tool used on a drilling tubular and having extensible members that remain decoupled with respect to the borehole wall during caliper measurements and while the extensible members are extended to allow movement in and through the borehole. A processor processes known and measured information to determine the size and shape of the borehole. Formation evaluation instruments may be included to allow formation evaluation substantially simultaneously with the caliper measurements.

대표청구항 ▼

What is claimed is: 1. An apparatus for determining a borehole dimension comprising: a) a tool conveyed in the borehole on an elongated tubular having a cutting tool for cutting into an earth formation; b) a selectively extensible member coupled to the tool, the extensible member being extensible f

What is claimed is: 1. An apparatus for determining a borehole dimension comprising: a) a tool conveyed in the borehole on an elongated tubular having a cutting tool for cutting into an earth formation; b) a selectively extensible member coupled to the tool, the extensible member being extensible from the tool toward the borehole wall; and c) a sensor operatively associated with the extensible member, wherein the extensible member remains substantially decoupled from the borehole wall while extended to allow the tubular to move in the borehole during at least a portion of time during operation of the sensor, the sensor providing an output signal relating to one or more of (i) a distance between a distal end of the extensible member and the borehole wall, and (ii) an amount of extension of the extensible member. 2. The apparatus of claim 1, wherein the extensible member comprises an arm member elastically coupled to the tool. 3. The apparatus of claim 1, wherein the extensible member comprises a first end and a second end, the extensible member pivotally mounted on the tool at the first end to allow the second end to extend angularly from a z-axis of the tool. 4. The apparatus of claim 1, wherein the extensible member comprises a first end and a second end, the extensible member pivotally mounted on the tool at the first end to allow the second end to extend angularly in a plane normal to a z-axis of the tool. 5. The apparatus of claim 1, wherein the extensible member comprises a curved arm having a first end and a second end, the curved arm being pivotally mounted on the tool at the first end to allow the second end to extend from the tool, the second end having a rolling member mounted thereon to inhibit tool coupling with respect to the borehole wall. 6. The apparatus of claim 1, wherein the extensible member comprises a piston extending in a radial direction from a z-axis of the tool. 7. The apparatus of claim 6, wherein the piston comprises a plurality of pistons disposed about a periphery of the tool. 8. The apparatus of claim 1, wherein the sensor comprises a first sensor and a second sensor, the first sensor determining an amount of extension of the extensible member, the second sensor operatively associated with a distal end of the extensible member, the extensible member extending to traverse only a portion of the distance between the tool and the borehole wall, the second sensor being used to determine a remaining distance between the extensible member distal end and the borehole wall. 9. The apparatus of claim 1, wherein the extensible member is selected from a group consisting of i) an oval wobble ring, ii) a buckle spring, iii) a torsion rib, and iv) an eccentric ring rotated about the borehole. 10. The apparatus of claim 1, wherein the cutting tool comprises a drill bit at a distal end of the elongated tubular. 11. The apparatus of claim 1, wherein the cutting tool comprises a reaming bit. 12. The apparatus of claim 1, wherein the cutting tool comprises a drill bit at a distal end of the elongated tubular and a reaming bit located on the elongated tubular above the drill bit. 13. The apparatus of claim 1, wherein the extensible member is extended during one or more of i) while tripping the drilling tubular from the borehole, ii) while drilling the borehole, and iii) while reaming the borehole. 14. The apparatus of claim 1, wherein the tool is located on the tubular near a formation evaluation instrument evaluating a formation parameter while the tool is operated to determine the borehole dimension at substantially the same time as the formation parameter is evaluated. 15. A method for determining a borehole dimension comprising: a) conveying a tool through the borehole on a tubular having a cutting tool for cutting into an earth formation; b) extending a selectively extensible member from the tool toward the borehole wall; c) generating a signal relating to one or more of i) a distance between a distal end of the extensible member and the borehole wall and ii) an amount of extension of the extensible member using a sensor operatively associated with the extensible member; and d) maintaining the extensible member substantially decoupled from the borehole wall while extended to allow the tubular to move in the borehole during at least a portion of time during operation of the sensor. 16. The method of claim 15, wherein the extensible member comprises a first end and a second end, the extensible member pivotally mounted on the tool at the first end, and extending the extensible member comprises extending the second end angularly in a plane normal to a z-axis of the tool. 17. The method of claim 15, wherein the sensor comprises a first sensor and a second sensor operatively associated with a distal end of the extensible member, wherein extending the extensible member comprises extending the extensible member to traverse only a portion of the distance between the tool and the borehole wall, the method further comprising: i) determining an amount of extension of the extensible member using the first sensor; and ii) determining a remaining distance between the extensible member distal end and the borehole wall using the second sensor. 18. The method of claim 15, wherein the extensible member is extended during one or more of i) while tripping the elongated tubular from the borehole, ii) while drilling the borehole, and iii) while reaming the borehole. 19. A system for determining a borehole dimension during drilling operations, the system comprising: a) a drilling apparatus comprising a drilling tubular having a drill bit for drilling the borehole; b) a tool conveyed in the borehole on the drilling tubular; c) a selectively extensible member coupled to the tool, the extensible member being extensible from the tool toward the borehole wall; d) a sensor operatively associated with the extensible member, wherein the extensible member remains substantially decoupled from the borehole wall while extended to allow the drilling tubular to move in the borehole during at least a portion of time during operation of the sensor, the sensor providing an output signal relating to one or more of i) a distance between a distal end of the extensible member and the borehole wall and ii) an amount of extension of the extensible member; and e) a processor processing the output signal, the processed output signal being indicative of the borehole dimension. 20. The system of claim 19, wherein the extensible member is extended during one or more of i) while tripping the drilling tubular from the borehole, ii) while drilling the borehole, and iii) while reaming the borehole. 21. The system of claim 19, wherein the tool is located on the drilling tubular near a formation evaluation instrument evaluating a formation parameter while the tool is operated to determine the borehole dimension at substantially the same time as the formation parameter is evaluated.