# US 2024/0200440 A1 · Maximizing Information Gain From Pipe Inspection Inversion > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2024/0200440 A1 - Document ID: US20240200440A1 - Status: Published application - Kind: A1 - Application number: 18/081,917 - Filed: 2022-12-15 - Published: 2024-06-20 - Earliest claimed: 2022-12-15 - Assignees: Halliburton Energy Services, Inc. - Applicants: Halliburton Energy Services, Inc. - Inventors: Ahmed Fouda; Christopher Michael Jones - Web page: https://patentgrep.com/patent/US20240200440A1 ## CPC - E21B 47/08: Measuring diameters or related dimensions at the borehole - E21B 47/006: {Detection of corrosion or deposition of substances} - G01V 3/28: using induction coils - G01V 3/38: Processing data, e.g. for analysis, for interpretation, for correction - 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 A method for estimating a thickness for each of a plurality of nested tubulars may include disposing an electromagnetic (EM) logging tool in a wellbore, transmitting an electromagnetic field from the transmitter into one or more tubulars to energize the one or more tubulars with the electromagnetic field thereby producing an eddy current, and measuring the electromagnetic field generated by the eddy current. Additionally, the method may include defining a prior distribution of at least one pipe thickness log based on the plurality of measurements, processing a first set of measurement depth points to estimate one or more tubulars at one or more depths in the wellbore, computing a posterior distribution of the thickness log based at least in part on the prior distribution and the one or more thicknesses, and determining a second set of measurement depth points to process based on the posterior distribution. ## Claims ### Claim 1 A method for estimating a thickness for each of a plurality of nested tubulars comprising: disposing an electromagnetic (EM) logging tool in a wellbore, wherein the EM logging tool comprises: a transmitter disposed on the EM logging tool; and a receiver disposed on the EM logging tool; transmitting an electromagnetic field from the transmitter into one or more tubulars to energize the one or more tubulars with the electromagnetic field thereby producing an eddy current in the one or more tubulars; measuring the electromagnetic field generated by the eddy current in the one or more tubulars with the receiver on at least one channel to obtain a plurality of measurements; defining a prior distribution of individual thickness curves from at least one pipe thickness log based on the plurality of measurements; processing a first set of depth point measurements to estimate one or more thicknesses of the one or more tubulars at one or more depths in the wellbore; computing a posterior distribution of the at least one pipe thickness log based at least in part on the prior distribution and the one or more thicknesses; and determining a second set of depth point measurements to process based on the posterior distribution. ### Claim 2 (depends on 1) The method of claim 1, wherein the plurality of measurements are in a time-domain or a frequency-domain. ### Claim 3 (depends on 1) The method of claim 1, wherein the prior distribution of the at least one pipe thickness log is based at least in part on one or more proxy logs. ### Claim 4 (depends on 1) The method of claim 1, wherein the prior distribution utilizes a non-linear inversion using a fast forward model to generate an individual thickness for each of the one or more tubulars. ### Claim 5 (depends on 1) The method of claim 1, further comprising utilizing a covariance matrix to define the prior distribution of the at least one pipe thickness log. ### Claim 6 (depends on 1) The method of claim 1, further comprising applying a Bayes' rule to compute the posterior distribution. ### Claim 7 (depends on 1) The method of claim 1, further comprising selecting a first batch of K depth points and performing an inversion on the first batch of K depth points. ### Claim 8 (depends on 1) The method of claim 1, wherein determining the second set of depth point measurements comprises determining a candidate depth point that has a variance in the posterior distribution that is largest. ### Claim 9 (depends on 1) The method of claim 1, wherein determining the second set of depth point measurements comprises determining a candidate depth point that has a first principal component of a posterior covariance matrix that is a highest projection. ### Claim 10 (depends on 1) The method of claim 1, wherein determining the second set of depth point measurements comprises determining a candidate depth point that results in a largest decrease in a differential entropy of the posterior distribution. ### Claim 11 (depends on 1) The method of claim 1, wherein a level of uncertainty for the first set of depth point measurements and the second set of depth point measurements is computed and continuously updated. ### Claim 12 (depends on 1) The method of claim 1, further comprising applying one or more stopping criteria to the second set of depth point measurements. ### Claim 13 (depends on 1) The method of claim 1, further comprising reconstructing the at least one pipe thickness log at one or more depth points that are not in the first set of depth point measurements or the second set of depth point measurements using a regression model. ### Claim 14 (depends on 13) The method of claim 13, wherein the regression model is trained at least in part on the first set of depth point measurements and the second set of depth point measurements. ### Claim 15 A system for estimating a thickness for each of a plurality of nested tubulars comprising: an electromagnetic (EM) logging tool comprising: a transmitter disposed on the EM logging tool for transmitting an electromagnetic field from the transmitter into one or more tubulars to energize the one or more tubulars with the electromagnetic field thereby producing an eddy current in the one or more tubulars; and a receiver disposed on the EM logging tool for measuring the electromagnetic field generated by the eddy current in the one or more tubulars with the receiver on at least one channel to obtain a plurality of measurements; and an information handling system communicatively connected to the EM logging to and configured to: define a prior distribution of individual thickness curves from at least one pipe thickness log based on the plurality of measurements; process a first set of depth point measurements to estimate one or more thicknesses of the one or more tubulars at one or more depths in the wellbore; compute a posterior distribution of the at least one pipe thickness log based at least in part on the prior distribution and the one or more thicknesses; and determine a second set of depth point measurements to process based on the posterior distribution. ### Claim 16 (depends on 15) The system of claim 15, wherein the plurality of measurements are in a time-domain or a frequency-domain. ### Claim 17 (depends on 15) The system of claim 15, wherein the prior distribution of the at least one pipe thickness log is based at least in part on one or more proxy logs. ### Claim 18 (depends on 15) The system of claim 15, wherein the prior distribution utilizes a non-linear inversion using a fast forward model to generate an individual thickness for each of the one or more tubulars. ### Claim 19 (depends on 15) The system of claim 15, wherein the information handling system is further configured to utilize a covariance matrix to define the prior distribution of the at least one pipe thickness log. ### Claim 20 (depends on 15) The system of claim 15, wherein the information handling system is further configured to apply Bayes' rule to compute the posterior distribution.