# US 2021/0277773 A1 · Iterative borehole correction > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0277773 A1 - Document ID: US20210277773A1 - Status: Published application - Kind: A1 - Application number: 16/623,499 - Filed: 2019-01-29 - Published: 2021-09-09 - Earliest claimed: 2019-01-29 - Assignees: Halliburton Energy Services, Inc. - Applicants: Halliburton Energy Services, Inc. - Inventors: Yijing Fan; Jin Ma; Li Pan - Web page: https://patentgrep.com/patent/US20210277773A1 ## CPC - E21B 47/113: using electrical indications; using light radiations - E21B 47/12: Means for transmitting measuring-signals or control signals from the well to the surface, or from the surface to the well, e.g. for logging while drilling - E21B 47/008: Monitoring of down-hole pump systems, e.g. for the detection of "pumped-off" conditions - E21B 47/02: Determining slope or direction - E21B 47/026: of penetrated ground layers - G01V 3/18: specially adapted for well-logging - G01V 3/38: Processing data, e.g. for analysis, for interpretation, for correction - G06F 16/9017: {using directory or table look-up (use of a directory or look-up table in file systems G06F16/13)} - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS - G01V: GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS (means for indicating the location of accidentally buried, e.g. snow-buried, persons A63B29/02) - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) ## Abstract Raw signal measurements can be received by sensors in a wellbore. Borehole effects can affect the raw signal measurements. The raw signal measurements can be converted into ratio signals having attenuation and phase shift. An apparent resistivity can be determined from the ratio signals. Mud resistivity can be determined based on apparent resistivity, at least part of the raw signal measurements, and the borehole size. A true resistivity can be determined based on the mud resistivity and at least part of the ratio signals. The raw signal measurements and the ratio signals can be updated based on the true resistivity. Steps can be repeated to determine a corrected true resistivity. Based on the true resistivity value and updated raw signal measurements and ratio signals, an operating characteristic of a well tool can be caused to be adjusted. ## Claims ### Claim 1 A system comprising: a processing device; and a non-transitory computer-readable medium including program code that is executable by the processing device for causing the processing device to: receive raw signal measurements affected by borehole effects from a downhole tool in a wellbore environment having a borehole size; convert the raw signal measurements to ratio signals representing attenuation and phase shift corresponding to the raw signal measurements; determine apparent resistivity from at least part of the ratio signals that are the least sensitive to the borehole effects; determine mud resistivity based on the apparent resistivity, at least part of the raw signal measurements that are most sensitive to the borehole effects, and the borehole size; determine a true resistivity based on the mud resistivity and the at least part of the ratio signals; update the raw signal measurements and the ratio signals based on the true resistivity; repeat steps of determining the apparent resistivity, the mud resistivity, and the true resistivity, and updating the raw signal measurements and the ratio signals to determine a corrected true resistivity at least until a ratio of resistivity, which represents a divergence between the apparent resistivity and the corrected true resistivity, is less than a selected threshold value; and cause an operating characteristic of a well tool to be adjusted based on the corrected true resistivity and the updated raw signal measurements and the ratio signals. ### Claim 2 (depends on 1) The system of claim 1, wherein converting the raw signal measurements to ratio signals representing attenuation and phase shift corresponding to the raw signal measurements comprises: analyzing the raw signal measurements to determine three-dimensional components of the raw signal measurements; and determining the ratio signals using the three-dimensional components, wherein one ratio signal is based on x-axis components of the three-dimensional components of the raw signal measurements and a second ratio signal is based on z-axis components of the three-dimensional components of the raw signal measurements, wherein the z-axis components are affectable by the borehole effects less than the x-axis components. ### Claim 3 (depends on 1) The system of claim 1, wherein determining the apparent resistivity includes retrieving an apparent resistivity value from a first lookup table based on the at least part of the ratio signals that are the least sensitive to the borehole effects, wherein determining the mud resistivity includes retrieving a mud resistivity value from a second lookup table based in part on the apparent resistivity value and the at least part of the raw signal measurements that are the most sensitive to the borehole effects, and wherein determining the true resistivity include retrieving a true resistivity value from the second lookup table based in part on the mud resistivity value. ### Claim 4 (depends on 3) The system of claim 3, wherein the non-transitory computer-readable medium comprises program code that is executable by the processing device for causing the processing device to: update the raw signal measurements and the ratio signals from the first lookup table based on the true resistivity value. ### Claim 5 (depends on 1) The system of claim 1, wherein causing an operating characteristic of a well tool to be adjusted based on the corrected true resistivity includes adjusting a rate-of-penetration value of the well tool. ### Claim 6 (depends on 1) The system of claim 1, wherein the downhole tool includes a first transmitter, a second transmitter, a first receiver, and a second receiver, the first transmitter being locatable at a distance downhole different from the second transmitter and the first receiver is positionable at an angle different from the second receiver. ### Claim 7 (depends on 1) The system of claim 1, wherein the ratio signals are affectable by the borehole effects less than the raw signal measurements are affectable by the borehole effects. ### Claim 8 A non-transitory computer-readable medium including program code that is executable by a processing device for causing the processing device to: receive raw signal measurements affected by borehole effects from a downhole tool in a wellbore environment having a borehole size; convert the raw signal measurements to ratio signals representing attenuation and phase shift corresponding to the raw signal measurements; determine apparent resistivity from at least part of the ratio signals that are the least sensitive to the borehole effects; determine mud resistivity based on the apparent resistivity, at least part of the raw signal measurements that are the most sensitive to the borehole effects, and the borehole size; determine a true resistivity based on the mud resistivity and the at least part of the ratio signals; update the raw signal measurements and the ratio signals based on the true resistivity; repeat steps of determining the apparent resistivity, the mud resistivity, and the true resistivity, and updating the raw signal measurements and the ratio signals to determine a corrected true resistivity at least until a ratio of resistivity, which represents a divergence between the apparent resistivity and the corrected true resistivity, is less than a selected threshold value; and cause an operating characteristic of a well tool to be adjusted based on the corrected true resistivity and the updated raw signal measurements and ratio signals. ### Claim 9 (depends on 8) The non-transitory computer-readable medium of claim 8, wherein converting the raw signal measurements to ratio signals representing attenuation and phase shift corresponding to the raw signal measurements comprises: analyzing the raw signal measurements to determine three-dimensional components of the raw signal measurements; and determining the ratio signals using the three-dimensional components, wherein one ratio signal is based on x-axis components of the three-dimensional components of the raw signal measurements and a second ratio signal is based on z-axis components of the three-dimensional components of the raw signal measurements, wherein the z-axis components are affectable by the borehole effects less than the x-axis components. ### Claim 10 (depends on 8) The non-transitory computer-readable medium of claim 8, wherein determining the apparent resistivity includes retrieving an apparent resistivity value from a first lookup table based on the at least part of the ratio signals that are the least sensitive to the borehole effects, wherein determining the mud resistivity includes retrieving a mud resistivity value from a second lookup table based in part on the apparent resistivity value and the at least part on the raw signal measurements that are the most sensitive to the borehole effects, and wherein determining the true resistivity include retrieving a true resistivity value from the second lookup table based in part on the mud resistivity value. ### Claim 11 (depends on 10) The non-transitory computer-readable medium of claim 10, wherein the non-transitory computer-readable medium further comprises program code that is executable by the processing device for causing the processing device to: update the raw signal measurements and the ratio signals from the first lookup table based on the true resistivity value. ### Claim 12 (depends on 8) The non-transitory computer-readable medium of claim 8, wherein causing an operating characteristic of a well tool to be adjusted based on the corrected true resistivity includes adjusting a rate-of-penetration value of the well tool. ### Claim 13 (depends on 8) The non-transitory computer-readable medium of claim 8, wherein the downhole tool includes a first transmitter, a second transmitter, a first receiver, and a second receiver, the first transmitter being locatable at a distance downhole different from the second transmitter and the first receiver is positionable at an angle different from the second receiver. ### Claim 14 (depends on 8) The non-transitory computer-readable medium of claim 8, wherein the ratio signals are affectable by the borehole effects less than the raw signal measurements are affectable by the borehole effects. ### Claim 15 A computer-implemented method comprising: receiving raw signal measurements affected by borehole effects from a downhole tool in a wellbore environment having a borehole size; converting the raw signal measurements to ratio signals representing attenuation and phase shift corresponding to the raw signal measurements; determining apparent resistivity from at least part of the ratio signals that are the least sensitive to the borehole effects; determining mud resistivity based on the apparent resistivity, at least part of the raw signal measurements that are the most sensitive to the borehole effects, and the borehole size; determining a true resistivity based on the mud resistivity and the at least part of the ratio signals; updating the raw signal measurements and the ratio signals based on the true resistivity; repeating steps of determining the apparent resistivity, the mud resistivity, and the true resistivity, and updating the raw signal measurements and the ratio signals to determine a corrected true resistivity at least until a ratio of resistivity, which represents a divergence between the apparent resistivity and the corrected true resistivity, is less than a selected threshold value; and causing an operating characteristic of a well tool to be adjusted based on the corrected true resistivity and the updated raw signal measurements and ratio signals. ### Claim 16 (depends on 15) The computer-implemented method of claim 15, wherein converting the raw signal measurements to ratio signals representing attenuation and phase shift corresponding to the raw signal measurements comprises: analyzing the raw signal measurements to determine three-dimensional components of the raw signal measurements; and determining the ratio signals using the three-dimensional components, wherein one ratio signal is based on x-axis components of the three-dimensional components of the raw signal measurements and a second ratio signal is based on z-axis components of the three-dimensional components of the raw signal measurements, wherein the z-axis components are affectable by the borehole effects less than the x-axis components. ### Claim 17 (depends on 15) The computer-implemented method of claim 15, wherein determining the apparent resistivity includes retrieving an apparent resistivity value from a first lookup table based on the at least part of the ratio signals that are the least sensitive to the borehole effects, wherein determining the mud resistivity includes retrieving a mud resistivity value from a second lookup table based in part on the apparent resistivity value and the at least part of the raw signal measurements that are the most sensitive to the borehole effects, and wherein determining the true resistivity include retrieving a true resistivity value from the second lookup table based in part on the mud resistivity value. ### Claim 18 (depends on 17) The computer-implemented method of claim 17, further comprising: updating the raw signal measurements and the ratio signals from the first lookup table based on the true resistivity value. ### Claim 19 (depends on 15) The computer-implemented method of claim 15, wherein causing an operating characteristic of a well tool to be adjusted based on the corrected true resistivity includes adjusting a rate-of-penetration value of the well tool. ### Claim 20 (depends on 15) The computer-implemented method of claim 15, wherein the ratio signals are affected by the borehole effects less than the raw signal measurements are affected by the borehole effects.