Cement validation by downhole ultrasonic measurements
A method comprises positioning a transducer assembly to a casing string disposed in a wellbore formed in a subsurface formation, wherein an annular area between the casing string and the subsurface formation is at least partially filled with sealant. The method comprises transmitting, via the transducer assembly, signals into a measurement channel of the transducer assembly that is at least partially filled with the sealant. The method comprises acquiring, via the transducer assembly, response signals in response to transmission of the signals through the measurement channel. The method comprises determining one or more characteristics of the sealant in the measurement channel based on the response signals.
1 . A method comprising:
positioning a transducer assembly to a casing string disposed in a wellbore formed in a subsurface formation, wherein an annular area between the casing string and the subsurface formation is at least partially filled with sealant;
transmitting, via the transducer assembly, signals into a measurement channel formed between a first fin and a second fin of the transducer assembly, the measurement channel being at least partially filled with the sealant, wherein a respective internal face of the first fin is parallel with the respective internal face of the second fin and spaced apart at a fixed distance to define a known signal path length;
acquiring, via the transducer assembly, response signals in response to transmission of the signals that have propagated through the measurement channel; and
determining one or more characteristics of the sealant within the measurement channel based on transit time or propagation speed of the response signals across the measurement channel, wherein determining the one or more characteristics includes determining a percent of sealant occupying the measurement channel based on the transit time or the propagation speed of the response signals across the measurement channel.
2 . The method of claim 1 , wherein the transducer assembly is positioned on a collar of the casing string or a body of the casing string, and wherein the transducer assembly is positioned internal or external to the casing string.
3 . The method of claim 1 , wherein the transducer assembly includes two or more fins.
4 . The method of claim 3 , wherein each of the fins is constructed of materials including steel or epoxy resin.
5 . The method of claim 3 , wherein the two or more fins are oriented parallel to a central axis of the casing string or in a spiral direction about an exterior of the casing string.
6 . The method of claim 1 , wherein the signals include ultrasonic signals.
7 . The method of claim 1 , further comprising:
measuring the transit time required for the signals to transition across the fixed distance of the measurement channel, wherein the fixed distance is a length between two or more fins;
determining the propagation speed of the signals transmitting through the fixed distance of the measurement channel; and
determining the one or more characteristics of the sealant based on the propagation speed of the signals.
8 . The method of claim 1 , wherein the one or more characteristics are determined during cementing operations include operations during circulation, operations during primary cementing, and operations during post cementing.
9 . The method of claim 1 , wherein the one or more characteristics include compressive strength of the sealant and a percent of the sealant at a location in the annular area proximate the transducer assembly.
10 . The method of claim 1 , wherein the sealant includes Portland cement, reduced Portland cement, Sorel cement, calcium aluminate-based cement, and epoxy resins.
11 . The method of claim 1 , wherein the transducer assembly electrically communicates to surface via a tubing encapsulated cable.
12 . A system comprising:
a transducer assembly positioned to a casing string disposed in a wellbore formed in a subsurface formation, wherein an annular area between the casing string and the subsurface formation is at least partially filled with sealant;
a processor; and
a computer-readable medium having instructions stored thereon that are executable by the processor to cause the processor to,
transmit, via the transducer assembly, signals into a measurement channel formed between a first fin and a second fin of the transducer assembly, the measurement channel being at least partially filled with the sealant, wherein a respective internal face of the first fin is parallel with the respective internal face of the second fin and spaced apart at a fixed distance to define a known signal path length;
acquire, via the transducer assembly, response signals in response to transmission of the signals that have propagated through the measurement channel; and
determine one or more characteristics of the sealant within the measurement channel based on transit time or propagation speed of the response signals across the measurement channel, wherein the one or more characteristics includes a percent of sealant occupying the measurement channel based on the transit time or the propagation speed of the response signals across the measurement channel.
13 . The system of claim 12 , wherein the transducer assembly is positioned on a collar of the casing string or a body of the casing string, and wherein the transducer assembly is positioned internally or external to the casing string.
14 . The system of claim 12 , wherein the transducer assembly includes two or more fins.
15 . The system of claim 14 , wherein each of the fins is constructed of materials including steel or epoxy resin.
16 . The system of claim 14 , wherein the two or more fins are oriented parallel to a central axis of the casing string or in a spiral direction about an exterior of the casing string.
17 . The system of claim 12 , wherein the transducer assembly electrically communicates to surface via a tubing encapsulated cable.
18 . An apparatus comprising;
a casing string disposed in a wellbore formed in a subsurface formation, wherein an annular area between the casing string and the subsurface formation is at least partially filled with sealant; and
a transducer assembly positioned on the casing string configured to,
transmit, via the transducer assembly, signals into a measurement channel formed between a first fin and a second fin of the transducer assembly, the measurement channel being at least partially filled with the sealant wherein a respective internal face of the first fin is parallel with the respective internal face of the second fin and spaced apart at a fixed distance to define a known signal path length; and
acquire, via the transducer assembly, response signals in response to transmission of the signals that have propagated through the measurement channel, wherein one or more characteristics of the sealant in the measurement channel are determined based on transit time or propagation speed of the response signals across the measurement channel, and wherein the one or more characteristics includes a percent of sealant occupying the measurement channel based on the transit time or the propagation speed of the response signals across the measurement channel.
19 . The apparatus of claim 18 , wherein the transducer assembly includes two or more fins.
20 . The apparatus of claim 19 , wherein the two or more fins are oriented parallel to a central axis of the casing string or in a spiral direction about an exterior of the casing string.