# US 10,309,799 B2 · Correction of rotation rate measurements > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,309,799 B2 - Document ID: US10309799B2 - Status: Granted - Kind: B2 - Application number: 15/865,083 - Filed: 2018-01-08 - Published: 2018-05-10 - Granted: 2019-06-04 - Earliest claimed: 2016-10-12 - Assignees: Gyrodata, Incorporated - Applicants: Gyrodata, Incorporated - Inventors: Adrián Guillermo Ledroz - Web page: https://patentgrep.com/patent/US10309799B2 ## CPC - G01C 25/00: Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass (testing, calibrating or compensating compasses G01C17/38) - E21B 47/022: of the borehole, e.g. using geomagnetism - E21B 47/024: of devices in the borehole (determining slope or direction of the borehole E21B47/022) - G01V 11/002: {Details, e.g. power supply systems for logging instruments, transmitting or recording data, specially adapted for well logging, also if the prospecting method is irrelevant (means for transmitting well survey signals E21B47/12; signal transmission systems in general G08C; transmission in general H04B)} - E21B 7/04: Directional drilling - G01C 19/5776: Signal processing not specific to any of the devices covered by groups G01C19/5607 - G01C19/5719 - G01C: MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY (measuring liquid level G01F; radio navigation, determining distance or velocity by use of propagation effects, e.g. Doppler effects, propagation time, of radio waves, analogous arrangements using other waves G01S) - 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) ## Abstract Various implementations directed to correction of rotation rate measurements are provided. In one implementation, a method may include receiving rotation rate measurements about a first axis and a second axis from first gyroscopic sensors. The method may include receiving a first rotation rate measurement about a third axis from a second gyroscopic sensor. The method may include determining an estimated rotation rate measurement about the third axis based on the rotation rate measurements about the first axis and the second axis. The method may include determining a bias value based on a difference between the first rotation rate measurement about the third axis and the estimated rotation rate measurement. The method may include receiving second rotation rate measurements about the third axis from the second gyroscopic sensor. The method may include correcting the second rotation rate measurements about the third axis based on the determined bias value. ## Claims ### Claim 1 A method, comprising: determining an estimated rotation rate measurement about a z-axis of a survey tool disposed in a wellbore using one or more rotation rate measurements about a x-axis of the survey tool and one or more rotation rate measurements about a y-axis of the survey tool; determining a bias value based on a difference between a first rotation rate measurement about a z-axis of the survey tool and the estimated rotation rate measurement; correcting one or more second rotation rate measurements about the z-axis of the survey tool based on the determined bias value; and determining one or more drilling operations based at least in part on the corrected one or more second rotation rate measurements. ### Claim 2 (depends on 1) The method of claim 1, wherein the one or more rotation rate measurements about the x-axis of the survey tool and the one or more rotation rate measurements about the y-axis of the survey tool are not indexed measurements. ### Claim 3 (depends on 1) The method of claim 1, wherein determining the estimated rotation rate measurement about the z-axis of the survey tool comprises determining the estimated rotation rate measurement about the z-axis using the Earth's rotation rate, the one or more rotation rate measurements about the x-axis of the survey tool, and the one or more rotation rate measurements about the y-axis of the survey tool. ### Claim 4 (depends on 1) The method of claim 1, wherein correcting the one or more second rotation rate measurements about the z-axis of the survey tool comprises subtracting the determined bias value from the one or more second rotation rate measurements about the z-axis of the survey tool. ### Claim 5 (depends on 1) The method of claim 1, wherein determining the estimated rotation rate measurement about the z-axis of the survey tool comprises determining the estimated rotation rate measurement about the z-axis based on a true latitude of the survey tool, one or more measurements of the Earth's gravitation vector, the one or more rotation rate measurements about the x-axis of the survey tool, and the one or more rotation rate measurements about the y-axis of the survey tool. ### Claim 6 (depends on 1) The method of claim 1, wherein the x-axis and the y-axis are substantially perpendicular to each other, wherein the x-axis and the y-axis are substantially perpendicular to the z-axis, and wherein the z-axis is substantially parallel to a longitudinal axis of the wellbore. ### Claim 7 (depends on 1) The method of claim 1, wherein the one or more rotation rate measurements about the x-axis of the survey tool, the one or more rotation rate measurements about the y-axis of the survey tool, the first rotation rate measurement about the z-axis of the survey tool, and the one or more second rotation rate measurements about the z-axis of the survey tool are obtained using one or more dual-axis gyroscopic sensors, one or more single-axis gyroscopic sensors, or combinations thereof. ### Claim 8 (depends on 7) The method of claim 7, wherein the one or more dual-axis gyroscopic sensors and the one or more single-axis gyroscopic sensors comprise one or more Coriolis vibratory gyroscopic sensors, one or more spinning mass gyroscopic sensors, one or more optical gyroscopic sensors, one or more microelectromechanical system (MEMS) gyroscopic sensors, or combinations thereof. ### Claim 9 A system, comprising: a survey tool disposed in a wellbore, comprising: one or more first gyroscopic sensors configured to provide one or more rotation rate measurements about a first axis of the survey tool, and to provide one or more rotation rate measurements about a second axis of the survey tool; and a second gyroscopic sensor configured to provide a first rotation rate measurement about a third axis of the survey tool, and to provide one or more second rotation rate measurements about the third axis of the survey tool; and a computing system, comprising: a processor; and a memory comprising a plurality of program instructions which, when executed by the processor, cause the processor to: determine an estimated rotation rate measurement about the third axis of the survey tool based on the one or more rotation rate measurements about the first axis of the survey tool and the one or more rotation rate measurements about the second axis of the survey tool; determine a bias value based on a difference between the first rotation rate measurement about the third axis of the survey tool and the estimated rotation rate measurement; correct the one or more second rotation rate measurements about the third axis of the survey tool based on the determined bias value; and determine one or more drilling operations based at least in part on the corrected one or more second rotation rate measurements. ### Claim 10 (depends on 9) The system of claim 9, wherein the program instructions which, when executed by the processor, cause the processor to determine the estimated rotation rate measurement about the third axis of the survey tool further comprise program instructions which, when executed by the processor, cause the processor to: determine the estimated rotation rate measurement about the third axis using the Earth's rotation rate, the one or more rotation rate measurements about the first axis of the survey tool, and the one or more rotation rate measurements about the second axis of the survey tool, wherein the one or more rotation rate measurements about the first axis of the survey tool and the one or more rotation rate measurements about the second axis of the survey tool are not indexed measurements. ### Claim 11 (depends on 9) The system of claim 9, wherein the program instructions which, when executed by the processor, cause the processor to determine the estimated rotation rate measurement about the third axis of the survey tool further comprise program instructions which, when executed by the processor, cause the processor to: determine an indexed rotation rate measurement about the first axis of the survey tool based on the one or more rotation rate measurements about the first axis of the survey tool; determine an indexed rotation rate measurement about the second axis of the survey tool based on the one or more rotation rate measurements about the second axis of the survey tool; and determine the estimated rotation rate measurement about the third axis using the Earth's rotation rate, the indexed rotation rate measurement about the first axis of the survey tool, and the indexed rotation rate measurement about the second axis of the survey tool. ### Claim 12 (depends on 9) The system of claim 9, wherein the program instructions which, when executed by the processor, cause the processor to correct the one or more second rotation rate measurements about the third axis of the survey tool further comprise program instructions which, when executed by the processor, cause the processor to subtract the determined bias value from the one or more second rotation rate measurements about the third axis of the survey tool. ### Claim 13 (depends on 9) The system of claim 9, wherein the computing system is disposed within the wellbore or disposed at a surface location. ### Claim 14 A method, comprising: determining a measured latitude of a survey tool disposed in a wellbore based on one or more measurements of the Earth's gravitation vector, one or more rotation rate measurements about a x-axis of the survey tool, one or more rotation rate measurements about a y-axis of the survey tool, and a first rotation rate measurement about a z-axis of the survey tool; determining a first bias value based on a true latitude of the survey tool and the measured latitude of the survey tool; correcting one or more second rotation rate measurements about the z-axis of the survey tool based on the first bias value; and determining one or more drilling operations based at least in part on the corrected one or more second rotation rate measurements. ### Claim 15 (depends on 14) The method of claim 14, wherein determining the first bias value comprises: determining a latitude error based on a difference between the true latitude and the measured latitude of the survey tool; and determining the first bias value based on the latitude error. ### Claim 16 (depends on 14) The method of claim 14, wherein correcting the one or more second rotation rate measurements about the z-axis of the survey tool comprises subtracting the first bias value from the one or more second rotation rate measurements about the z-axis of the survey tool. ### Claim 17 (depends on 14) The method of claim 14, further comprising determining an azimuth of the survey tool based on the corrected one or more second rotation rate measurements. ### Claim 18 (depends on 14) The method of claim 14, further comprising: determining an estimated rotation rate measurement about the z-axis of the survey tool based on the one or more rotation rate measurements about the x-axis of the survey tool and the one or more rotation rate measurements about the y-axis of the survey tool; and determining a second bias value based on a difference between the first rotation rate measurement about the z-axis of the survey tool and the estimated rotation rate measurement; determining a third bias value based on the first bias value and the second bias value; and correcting the one or more second rotation rate measurements about the z-axis of the survey tool based on the third bias value. ### Claim 19 (depends on 18) The method of claim 18, wherein determining the third bias value comprises: determining the third bias value based on an average of the first bias value and the second bias value; determining the third bias value based on a Kalman filtering technique performed on the measured latitude, the one or more rotation rate measurements about the x-axis of the survey tool, the one or more rotation rate measurements about the y-axis of the survey tool, the first rotation rate measurement about the z-axis of the survey tool, or combinations thereof; determining the third bias value based on a least squares estimation process performed on the measured latitude, the one or more rotation rate measurements about the x-axis of the survey tool, the one or more rotation rate measurements about the y-axis of the survey tool, the first rotation rate measurement about the z-axis of the survey tool, or combinations thereof; or combinations thereof. ### Claim 20 (depends on 18) The method of claim 18, further comprising determining an azimuth of the survey tool based on the one or more second rotation rate measurements about the z-axis of the survey tool corrected based on the third bias value.