# US 8,542,553 B2 · Downhole sonic logging tool including irregularly spaced receivers > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,542,553 B2 - Document ID: US8542553B2 - Status: Granted - Kind: B2 - Application number: 12/700,546 - Filed: 2010-02-04 - Published: 2011-08-04 - Granted: 2013-09-24 - Earliest claimed: 2010-02-04 - Assignees: Schlumberger Technology Corporation - Applicants: Tsili Wang - Inventors: Tsili Wang - Web page: https://patentgrep.com/patent/US8542553B2 ## CPC - G01V 1/46: Data acquisition - 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 downhole acoustic measurement tool includes at least one transmitter longitudinally spaced apart from a non-uniformly spaced longitudinal array of acoustic receivers. The array has a non-uniform spacing such that a first spacing between a first pair of consecutive acoustic receivers in the array is not equal to a second spacing between a second pair of consecutive acoustic receivers in the array. Non-uniform spacing of the receivers in the array reduces aliasing when the received waveforms are processed, for example, to obtain semblance data. ## Claims ### Claim 1 A downhole acoustic measurement tool, comprising: a downhole tool body; at least one acoustic transmitter deployed on the tool body, the transmitter configured to transmit an acoustic waveform into a subterranean borehole; an array of receivers deployed on an external surface of the tool body, the array including a plurality of longitudinally spaced apart acoustic receivers, the acoustic receivers being longitudinally spaced apart from the transmitter and configured to receive said transmitted acoustic waveform, the array having a non-uniform spacing such that a first spacing between a first pair of consecutive acoustic receivers in the array is not equal to a second spacing between a second pair of consecutive acoustic receivers in the array: and wherein the array comprises first and second longitudinally spaced subarrays, each of the subarrays including a plurality of said acoustic receivers, the acoustic receivers in each subarray being uniformly spaced, the first and second subarrays being spaced apart from one another by a distance that is less than a distance between consecutive ones of the acoustic receivers in either of the first and second subarrays. ### Claim 2 (depends on 1) The downhole tool of claim 1, wherein the array comprises a linear array of acoustic receivers. ### Claim 3 (depends on 1) The downhole tool of claim 1, wherein the plurality of subarrays comprises first and second subarrays, the first and second subarrays being at least partially interleaved with one another. ### Claim 4 (depends on 1) The downhole tool of claim 1, wherein the non-uniformly spaced array includes at least five acoustic receivers. ### Claim 5 (depends on 1) The downhole tool of claim 1 further comprising a controller, the controller configured to (i) cause the transmitter to transmit an acoustic waveform, (ii) cause the non-uniformly spaced array of acoustic receivers to receive corresponding acoustic waveforms, and (iii) process said received waveforms to obtain semblance data. ### Claim 6 (depends on 5) The downhole tool of claim 5, wherein the controller is further configured to (iv) process the semblance data to obtain a shear wave slowness. ### Claim 7 A downhole acoustic measurement tool, comprising: a downhole tool body; at least one acoustic transmitter deployed on the tool body, the transmitter configured to transmit an acoustic waveform into a subterranean borehole; and an array of receivers deployed on an external surface of the tool body, the array including first and second subarrays; each of the first and second subarrays comprising a plurality of longitudinally spaced apart acoustic receivers, the acoustic receivers being longitudinally spaced apart from the transmitter and configured to receive said transmitted acoustic waveform; the first subarray having a first spacing between consecutive receivers, the second subarray having a second spacing between consecutive receivers, wherein the first spacing is not equal to the second spacing, and wherein the first and second subarrays are longitudinally spaced apart from one another by a third spacing, the third spacing being equal to one of the first and second spacings. ### Claim 8 (depends on 7) The downhole tool of claim 7, wherein the array comprises a linear array of acoustic receivers. ### Claim 9 (depends on 7) The downhole tool of claim 7, wherein each of the first and second subarrays comprises at least three acoustic receivers. ### Claim 10 A downhole acoustic: measurement tool, comprising: a downhole tool body; at least one acoustic transmitter deployed on the tool body, the transmitter configured to transmit an acoustic waveform into a subterranean borehole; an array of receivers deployed on an external surface of the tool body, the array including first and second subarrays; each of the first and second subarrays including a plurality of longitudinally spaced apart acoustic receivers, the acoustic receivers being longitudinally spaced apart from the transmitter and configured to receive said transmitted acoustic waveform; and the first subarray having a first spacing between consecutive receivers, the second array having a second spacing between consecutive receivers, the first spacing being equal to the second spacing, and the second subarray being longitudinally spaced apart from the first array by a third spacing that differs from at least one of the first spacing and the second spacing. ### Claim 11 (depends on 10) The downhole tool of claim 10, wherein the third spacing is less than the first spacing. ### Claim 12 (depends on 10) The downhole tool of claim 10, wherein the third spacing is greater than the first spacing. ### Claim 13 A downhole acoustic measurement tool, comprising: a downhole tool body: at least one transmitter deployed on the tool body, the transmitter configured to transmit an acoustic waveform into a subterranean borehole; an array of receivers deployed on an external surface of the tool body, the array including first and second subarrays; each of the first and second subarrays including a plurality of longitudinally spaced apart acoustic receivers, the acoustic receivers being longitudinally spaced apart from the transmitter and configured to receive said transmitted acoustic waveform, the first and second subarrays having identical spacing between consecutive receivers; at least a portion of the second subarray being interleaved with at least a portion of the first subrrays so as to define an interarray distance that is less than one-half the spacing between consecutive receivers in the first array. ### Claim 14 (depends on 13) The downhole tool of claim 13, wherein, the first and second subarrays are fully interleaved with one another. ### Claim 15 A downhole acoustic measurement tool, comprising: a downhole tool body; at least one acoustic transmitter deployed on the tool body, the transmitter configured to transmit an acoustic waveform into a subterranean borehole; an array of receivers deployed on an external surface of the tool body, the array including a plurality of longitudinally spaced apart acoustic receivers, the acoustic receivers being longitudinally spaced apart from the transmitter and configured to receive said transmitted acoustic waveform, the array having a non-uniform spacing such that a first spacing between a first pair of consecutive acoustic receivers in the array is not equal to a second spacing between a second pair of consecutive acoustic receivers in the array; and the array of receivers including first and second subarrays, the first and second subarrays being at least partially interleaved with one another.