# US 9,038,452 B2 · Systems and methods for measuring forces acting on a downhole tool > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,038,452 B2 - Document ID: US9038452B2 - Status: Granted - Kind: B2 - Application number: 13/546,725 - Filed: 2012-07-11 - Published: 2014-01-16 - Granted: 2015-05-26 - Earliest claimed: 2012-07-11 - Assignees: Schlumberger Technology Corporation - Applicants: Che-Keung Lawrence Lee - Inventors: Che-Keung Lawrence Lee - Web page: https://patentgrep.com/patent/US9038452B2 ## CPC - E21B 47/007: Measuring stresses in a pipe string or casing (for locating blocked portions of pipes E21B47/09) - E21B 47/01: Devices for supporting measuring instruments on drill bits, pipes, rods or wirelines; Protecting measuring instruments in boreholes against heat, shock, pressure or the like - G01L 5/0004: {Force transducers adapted for mounting in a bore of the force receiving structure (G01L5/0009 takes precedence)} - G01L 5/169: using magnetic means - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS - G01L: MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (weighing G01G) ## Abstract An apparatus for measuring forces acting on a downhole tool is provided. The apparatus can include an annular body having an axial bore formed therethrough. A first fluid can be disposed within the bore. An annular sleeve can be disposed proximate an inner surface of the body. An annular chamber can be formed between the body and the sleeve, and a second fluid can be disposed within the chamber. A sensor can be coupled to the sleeve to measure a strain placed on the sleeve by a pressure differential between the first and second fluids. A pressure of the first fluid in the bore can be determined from the strain. ## Claims ### Claim 1 An apparatus for measuring forces acting on a downhole tool, comprising: an annular body having an axial bore formed therethrough, wherein a first fluid is disposed within the bore; an annular sleeve disposed proximate an inner surface of the body; an annular chamber formed between the body and the sleeve; a second fluid disposed within the chamber; a first sensor coupled to the sleeve to measure a strain placed on the sleeve by a pressure differential between the first and second fluids, wherein a pressure of the first fluid in the bore is determined from the strain; a cover disposed proximate an outer surface of the body, wherein a second chamber is formed between the body and the cover, wherein a third fluid is disposed with the second chamber; and a second sensor coupled to the sleeve to measure a strain placed on the sleeve by a pressure differential between the first fluid and the second fluid. ### Claim 2 (depends on 1) The apparatus of claim 1, wherein the sleeve is disposed within an annular recess in the body such that an inner surface of the sleeve has substantially the same diameter as the inner surface of the body. ### Claim 3 (depends on 1) The apparatus of claim 1, wherein a gap is disposed adjacent an end of the sleeve such that the sleeve is free to expand axially in response to the pressure differential. ### Claim 4 (depends on 3) The apparatus of claim 3, wherein the gap is formed between the end of the sleeve and the body. ### Claim 5 (depends on 4) The apparatus of claim 4, wherein a length of the gap is between 0.5 mm and 5 cm. ### Claim 6 (depends on 1) The apparatus of claim 1, wherein the second sensor is coupled to an outer surface of the sleeve. ### Claim 7 (depends on 1) The apparatus of claim 1, wherein the second fluid has a pressure less than 10 MPa. ### Claim 8 (depends on 1) The apparatus of claim 1, wherein the second sensor is selected from the group consisting of a strain gauge sensor, an optical sensor, a capacitive sensor, an electromagnetic sensor, a piezoelectric sensor, and a potentiometric sensor. ### Claim 9 (depends on 1) The apparatus of claim 1, wherein the first sensor is coupled to an inner surface of the body. ### Claim 10 (depends on 1) The apparatus of claim 1, wherein the first sensor is coupled to an inner surface of the body, an outer surface of the body, or both. ### Claim 11 An apparatus for measuring forces acting on a downhole tool, comprising: an annular body having an axial bore formed therethrough, wherein a first fluid is disposed within the bore; a sleeve disposed proximate an inner surface of the body, wherein a first chamber is formed between the body and the sleeve, and wherein a second fluid is disposed within the first chamber; a cover disposed proximate an outer surface of the body, wherein a second chamber is formed between the body and the cover, wherein a third fluid is disposed within the second chamber, and wherein a pressure differential between the second and third fluids is less than 1000 kPa; a first sensor coupled to a load bearing portion of the body between the first and second chambers to measure a strain placed on the body by an axial load on the body, wherein the axial load is determined from the strain; and a hole formed through the load bearing portion of the body to place the first chamber in fluid communication with the second chamber to enable the pressures of the second and third fluids to equalize. ### Claim 12 (depends on 11) The apparatus of claim 11, wherein the second fluid has the same pressure as the third fluid. ### Claim 13 (depends on 11) The apparatus of claim 11, wherein the first sensor is coupled to an inner surface of the body. ### Claim 14 (depends on 11) The apparatus of claim 11, wherein the first sensor is coupled to an inner surface of the body, an outer surface of the body, or both. ### Claim 15 (depends on 11) The apparatus of claim 11, wherein an inner surface of the cover is aligned with an outer surface of the body. ### Claim 16 (depends on 11) The apparatus of claim 11, wherein the first sensor is selected from the group consisting of a strain gauge sensor, an optical sensor, a capacitive sensor, an electromagnetic sensor, a piezoelectric sensor, and a potentiometric sensor. ### Claim 17 (depends on 11) The apparatus of claim 11, further comprising a second sensor coupled to the sleeve to measure a strain placed on the sleeve by a pressure differential between the first fluid and the second fluid. ### Claim 18 A method for measuring forces acting on a downhole tool, comprising: running the downhole tool into a wellbore, the downhole tool comprising: an annular body having an axial bore formed therethrough, wherein a first fluid is disposed within the bore; a sleeve disposed proximate an inner surface of the body, wherein a first chamber is formed between the body and the sleeve, and wherein a second fluid is disposed within the first chamber; a cover disposed proximate an outer surface of the body, wherein a second chamber is formed between the body and the cover, wherein a third fluid is disposed within the second chamber, and wherein a pressure differential between the second and third fluids is less than 1000 kPa; and measuring a strain on the sleeve with a sensor coupled thereto, wherein the strain is caused by a pressure differential between the first and second fluids, and wherein a pressure of the first fluid is determined from the strain. ### Claim 19 (depends on 18) The method of claim 18, further comprising expanding the sleeve in an axial direction in response to the pressure differential between the first and second fluids. ### Claim 20 (depends on 18) The method of claim 18, further comprising measuring a strain on a load bearing portion of the body with a sensor coupled thereto, wherein the load bearing portion of the body is disposed between the first and second chambers, and wherein an axial load on the body is determined from the strain.