# US 2021/0277767 A1 · Techniques for evaluating borehole subsurface geologies using stoneley waves > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0277767 A1 - Document ID: US20210277767A1 - Status: Published application - Kind: A1 - Application number: 16/338,883 - Filed: 2017-11-30 - Published: 2021-09-09 - Earliest claimed: 2016-12-30 - Assignees: Halliburton Energy Services, Inc. - Applicants: Halliburton Energy Services, Inc. - Inventors: Brian Edward HORNBY; Mark Vincent COLLINS - Web page: https://patentgrep.com/patent/US20210277767A1 ## CPC - E21B 47/0025: {generating an image of the borehole wall using down-hole measurements, e.g. acoustic or electric} - E21B 47/00: Survey of boreholes or wells (monitoring pressure or flow of drilling fluid E21B21/08) - E21B 47/107: using acoustic means - G01V 1/00: Seismology; Seismic or acoustic prospecting or detecting - G01V 1/50: Analysing data - G01V 1/40: specially adapted for well-logging - G01V 2200/16: Measure-while-drilling or logging-while-drilling - G01V 2210/54: Borehole-related corrections - G01V 2210/646: Fractures - 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 evaluating borehole subsurface geologies can include receiving a total response signal by a sensor array disposed in a borehole, the response signal represents a pressure wave propagating in the borehole. A secondary signal can be extracted from the total response signal and a depth location for at least one secondary source that corresponds to the secondary signal is determined. An estimated reflectivity response for the secondary signal as a function of frequency is determined and the estimated reflectivity response is inverted to determine the secondary source includes at least one of a potential fracture or a potential washout. The at least one of a fracture conductivity or a washout volume for the secondary source is compared to one or more borehole images corresponding to the depth location of the secondary source to determine the potential fracture is an actual fracture or the potential washout is an actual washout. ## Claims ### Claim 1 A method comprising: receiving a total response signal by a sensor array disposed in a borehole, the response signal represents a pressure wave propagating in the borehole; extracting a secondary signal from the total response signal; determining a depth location for at least one secondary source that corresponds to the secondary signal; determining an estimated reflectivity response for the secondary signal as a function of frequency; inverting the estimated reflectivity response to determine the secondary source includes at least one of a potential fracture or a potential washout; and comparing at least one of a fracture conductivity or a washout volume for the secondary source to one or more borehole images corresponding to the depth location of the secondary source to determine the potential fracture is an actual fracture or the potential washout is an actual washout. ### Claim 2 (depends on 1) The method of claim 1, wherein receiving the total response signal further comprises: receiving the total response signal over a plurality of depth locations in the borehole. ### Claim 3 (depends on 1) The method of claim 1, wherein extracting the secondary signal from the total response signal further comprises: separating the secondary signal from the total response signal by stack shifting one or more waveforms in the total response signal. ### Claim 4 (depends on 3) The method of claim 3, wherein the total response signal includes a plurality of waveforms, the method further comprising: cross-correlating a first set of waveforms of the plurality of waveforms corresponding to a first depth to a second set of waveforms of the plurality of waveforms corresponding to a second depth to estimate a time shift coefficient for stack shifting the one or more waveforms in the total response signal, and wherein, separating a direct signal and the secondary signal further includes separating the direct signal and the secondary signal based on stack shifting the one or more waveforms based on the time shift coefficient. ### Claim 5 (depends on 1) The method of claim 1, wherein cementing operations are determined based on fracture conductivity or washout volume. ### Claim 6 (depends on 1) The method of claim 1, wherein mud weight is determined based on fracture conductivity or washout volume. ### Claim 7 A borehole tool comprising: one or more sensors to detect pressure changes in a borehole; a processor coupled to the one or more sensors and adapted to execute one or more processes; and a memory configured to store a process executable by the processor, the process, when executed, is operable to: receive a total response signal by the one or more sensors, the response signal represents a pressure wave propagating in the borehole; extract a secondary signal from the total response signal; determine a depth location for at least one secondary source that corresponds to the secondary signal; determine an estimated reflectivity response for the secondary signal as a function of frequency; inverting the estimated reflectivity response to determine the secondary source includes at least one of a potential facture or a potential washout; and compare the at least one of a fracture conductivity or a washout volume to borehole images corresponding to the depth location to determine the potential fracture is an actual fracture or the potential washout is an actual washout. ### Claim 8 (depends on 7) The borehole tool of claim 7, wherein the process to receive the total response signal, when executed, is further operable to: receive the total response signal over a plurality of depth locations in the borehole. ### Claim 9 (depends on 7) The borehole tool of claim 7, wherein the process to extract the secondary signal, when executed, is further operable to: separate the secondary signal from the total response signal by stack shifting one or more waveforms in the total response signal. ### Claim 10 (depends on 9) The borehole tool of claim 9, wherein the total response signal includes a plurality of waveforms, wherein the process, when executed, is further operable to: cross-correlate a first set of waveforms of the plurality of waveforms corresponding to a first depth to a second set of waveforms of the plurality of waveforms corresponding to a second depth to estimate a time shift coefficient for stack shifting the one or more waveforms in the total response signal, and wherein, the process to separate a direct signal and the secondary signal, when executed, is further operable to: separate a direct signal and the secondary signal based on stack shifting the one or more waveforms based on the time shift coefficient. ### Claim 11 (depends on 7) The borehole tool of claim 7, wherein cementing operations are determined based on fracture conductivity or washout volume. ### Claim 12 (depends on 7) The borehole tool of claim 7, wherein mud weight is determined based on fracture conductivity or washout volume. ### Claim 13 A tangible, non-transitory, computer-readable media having software encoded thereon, the software, when executed by a processor, operable to: receive a total response signal the response signal represents a pressure wave propagating in a borehole; extract a secondary signal from the total response signal; determine a depth location for at least one secondary source that corresponds to the secondary signal; determine an estimated reflectivity response for the secondary signal as a function of frequency; inverting the estimated reflectivity response to determine the secondary source includes at least one of a potential facture or a potential washout; and compare the at least one of a fracture conductivity or a washout volume to borehole images corresponding to the depth location to determine the potential fracture is an actual fracture or the potential washout is an actual washout. ### Claim 14 (depends on 13) The tangible, non-transitory, computer-readable media of claim 13, wherein the software, when executed by the processor to receive the total response signal, is further operable to: receive the total response signal over a plurality of depth locations in the borehole. ### Claim 15 (depends on 14) The tangible, non-transitory, computer-readable media of claim 14, wherein the software, when executed by the processor to extract the secondary signal, is further operable to: separate the secondary signal from the total response signal by stack shifting one or more waveforms in the total response signal. ### Claim 16 A method comprising: determining a depth location for a secondary source based on a response signal received by a sensor array disposed in a borehole; analyzing the response signal to determine the secondary source includes at least one of a potential fracture or a potential washout; and comparing at least one of a fracture conductivity or a washout volume for the secondary source to one or more borehole images corresponding to the depth location of the secondary source to determine the potential fracture is an actual fracture or the potential washout is an actual washout. ### Claim 17 (depends on 16) The method of claim 16, wherein the response signal includes a plurality of depth locations in the borehole. ### Claim 18 (depends on 16) The method of claim 16, wherein determining a depth location for a secondary source further comprises: extracting the secondary source from the response signal; and separating the secondary source from the response signal by stack shifting one or more waveforms in the response signal. ### Claim 19 (depends on 18) The method of claim 18, wherein the response signal includes a plurality of waveforms, the method further comprising: cross-correlating a first set of waveforms of the plurality of waveforms corresponding to a first depth to a second set of waveforms of the plurality of waveforms corresponding to a second depth to estimate a time shift coefficient for stack shifting the one or more waveforms in the response signal, and wherein, separating a direct signal and the secondary signal further includes separating the direct signal and the secondary signal based on stack shifting the one or more waveforms based on the time shift coefficient. ### Claim 20 (depends on 16) The method of claim 16, wherein cementing operations are determined based on fracture conductivity or washout volume.