US2014321240A1PendingUtilityA1

Elastography for cement integrity inspection

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Individually held — no corporate assignee on recordPriority: Apr 26, 2013Filed: Apr 26, 2013Published: Oct 30, 2014
Est. expiryApr 26, 2033(~6.8 yrs left)· nominal 20-yr term from priority
Inventors:Stephen R. BarnesThomas J. O'Donnell
E21B 47/005G01V 1/50E21B 47/0005E21B 47/101E21B 47/107
36
PatentIndex Score
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Claims

Abstract

A method for examining integrity of cement in a wellbore includes deploying an ultrasound transducer within a wellbore. One or more reference ultrasound images of the cement within the wellbore are acquired. A pushing pulse is emitted from the ultrasound transducer to elicit a displacement of the cement within the wellbore. A sequence of ultrasound images is acquired, over time, depicting the displacement of the cement within the wellbore elicited by the pushing pulse. A strain tensor map is generated from a difference between the one or more reference ultrasound images and the acquired sequence of ultrasound images. A degree of integrity of the cement within the wellbore is determined based on the generated strain tensor map.

Claims

exact text as granted — not AI-modified
What is claimed is: 
     
         1 . A method for examining integrity of cement in a wellbore, comprising:
 deploying an ultrasound transducer within a wellbore;   acquiring one or more reference ultrasound images of the cement within the wellbore;   emitting a pushing pulse from the ultrasound transducer to elicit a displacement of the cement within the wellbore;   acquiring a sequence of ultrasound images, over time, depicting the displacement of the cement within the wellbore elicited by the pushing pulse;   generating a strain tensor map from a difference between the one or more reference ultrasound images and the acquired sequence of ultrasound images; and   determining a degree of integrity of the cement within the wellbore based on the generated strain tensor map.   
     
     
         2 . The method of  claim 1 , wherein the pushing pulse emitted from the ultrasound transducer elicits a displacement of the cement within a range of about ten to about one hundred microns. 
     
     
         3 . The method of  claim 1 , wherein the ultrasound transducer used to emit the pushing pulse is also used to acquire the sequence of ultrasound images. 
     
     
         4 . The method of  claim 1 , wherein determining the degree of integrity of the cement within the wellbore based on the generated strain tensor map includes:
 identifying one or more subregions within the cement based on disparities within the stain tensor map;   characterizing each subregion within the cement based on values of the strain tensor map for each subregion and known strain tensors for various materials including cement, fluid and gas; and   determining if there is one or more channels present within the cement based on the characterizations of the subregions.   
     
     
         5 . The method of  claim 1 , wherein when the integrity of the cement within the wellbore is determined to be sufficiently poor, remedial actions are performed to improve the integrity of the cement. 
     
     
         6 . The method of  claim 5 , wherein the remedial action includes agitating the cement within the wellbore before the cement hardens or pumping additional cement into the wellbore. 
     
     
         7 . The method of  claim 6 , wherein agitation includes application of a focused acoustic beam. 
     
     
         8 . The method of  claim 7 , wherein the focused acoustic beam causes liquefaction within the cement. 
     
     
         9 . A method for deploying cement in a wellbore, comprising:
 pumping cement into a wellbore;   deploying an ultrasound transducer into the wellbore;   emitting a pushing pulse from the ultrasound transducer to elicit a displacement of the cement within the wellbore;   acquiring a sequence of ultrasound images, over time, depicting the displacement of the cement within the wellbore elicited by the pushing pulse;   generating a strain tensor map from the acquired sequence of ultrasound images;   detecting the presence of channels within the cement within the wellbore based on the generated strain tensor map; and   agitating the cement within the wellbore to reduce the channels when it is determined that channels are present within the cement.   
     
     
         10 . The method of  claim 9 , wherein agitation includes application of a focused acoustic beam. 
     
     
         11 . The method of  claim 10 , wherein the focused acoustic beam causes liquefaction within the cement. 
     
     
         12 . The method of  claim 9 , wherein the pushing pulse emitted from the ultrasound transducer elicits a displacement of the cement within a range of about ten to about one hundred microns. 
     
     
         13 . The method of  claim 9 , wherein detecting the presence of channels within the cement within the wellbore based on the generated strain tensor map includes:
 identifying one or more subregions within the cement based on disparities within the stain tensor map;   characterizing each subregion within the cement based on values of the strain tensor map for each subregion and known strain tensors for various materials including cement, fluid and gas; and   determining if there is one or more channels present within the cement based on the characterizations of the subregions.   
     
     
         14 . A computer system comprising:
 a processor; and   a non-transitory, tangible, program storage medium, readable by the computer system, embodying a program of instructions executable by the processor to perform method steps for examining integrity of cement in a wellbore, the method comprising:   controlling a deployment of an ultrasound transducer within a wellbore;   controlling an emission of a pushing pulse from the ultrasound transducer to elicit a displacement of the cement within the wellbore;   acquiring a sequence of ultrasound images, over time, depicting the displacement of the cement within the wellbore elicited by the pushing pulse;   generating a strain tensor map from the acquired sequence of ultrasound images; and   determining a degree of integrity of the cement within the wellbore based on the generated strain tensor map.   
     
     
         15 . The computer system of  claim 14 , wherein the pushing pulse emitted from the ultrasound transducer elicits a displacement of the cement within a range of about ten to about one hundred microns. 
     
     
         16 . The computer system of  claim 14 , wherein determining the degree of integrity of the cement within the wellbore based on the generated strain tensor map includes:
 identifying one or more subregions within the cement based on disparities within the stain tensor map;   characterizing each subregion within the cement based on values of the strain tensor map for each subregion and known strain tensors for various materials including cement, fluid and gas; and   determining if there is one or more channels present within the cement based on the characterizations of the subregions.   
     
     
         17 . The computer system of  claim 14 , wherein when the integrity of the cement within the wellbore is determined to be sufficiently poor, remedial actions are performed to improve the integrity of the cement. 
     
     
         18 . The computer system of  claim 17 , wherein the remedial action includes agitating the cement within the wellbore before the cement hardens. 
     
     
         19 . The computer system of  claim 18 , wherein agitation includes application of a focused acoustic beam. 
     
     
         20 . The computer system of  claim 19 , wherein the focused acoustic beam causes liquefaction within the cement. 
     
     
         21 . A computer system comprising:
 a processor; and   a non-transitory, tangible, program storage medium, readable by the computer system, embodying a program of instructions executable by the processor to perform method steps for deploying cement in a wellbore, the method comprising:   controlling a pumping of cement into a wellbore;   controlling a deployment of an ultrasound transducer into the wellbore;   controlling an emission of a pushing pulse from the ultrasound transducer to elicit a displacement of the cement within the wellbore;   acquiring a sequence of ultrasound images, over time, depicting the displacement of the cement within the wellbore elicited by the pushing pulse;   generating a strain tensor map from the acquired sequence of ultrasound images;   detecting the presence of channels within the cement within the wellbore based on the generated strain tensor map; and   controlling an agitating of the cement within the wellbore to reduce the channels when it is determined that channels are present within the cement.   
     
     
         22 . The computer system of  claim 20 , wherein the pushing pulse emitted from the ultrasound transducer elicits a displacement of the cement within a range of about ten to about one hundred microns. 
     
     
         23 . The computer system of  claim 20 , wherein detecting the presence of channels within the cement within the wellbore based on the generated strain tensor map includes:
 identifying one or more subregions within the cement based on disparities within the stain tensor map;   characterizing each subregion within the cement based on values of the strain tensor map for each subregion and known strain tensors for various materials including cement, fluid and gas; and   determining if there is one or more channels present within the cement based on the characterizations of the subregions.   
     
     
         24 . The computer system of  claim 21 , wherein agitation includes application of a focused acoustic beam. 
     
     
         25 . The computer system of  claim 24 , wherein the focused acoustic beam causes liquefaction within the cement.

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