Cement strength evaluation in a simulated downhole setting with acoustic measurements
A cement bond test cell includes an outer cylinder and an inner cylinder coaxially disposed within the outer cylinder along a central axis. The inner cylinder defines an inner volume configured to be filled with a fluid. An annulus is formed between the outer cylinder and the inner cylinder and configured to be filled with a test cement. The cement bond test cell further includes an acoustic transmitter disposed within the inner volume and configured to be acoustically coupled to an interior surface of the inner cylinder by the fluid. The cement bond test cell further includes at least one acoustic receiver acoustically coupled to an exterior surface of the outer cylinder.
1. A cement bond test cell for use in a test chamber, comprising:
an outer cylinder;
an inner cylinder coaxially disposed within the outer cylinder along a central axis, wherein the inner cylinder defines an inner volume configured to be filled with a fluid, and wherein an annulus is formed between the outer cylinder and the inner cylinder and configured to be filled with a test cement;
an acoustic transmitter disposed within the inner volume and configured to be acoustically coupled to an interior surface of the inner cylinder by the fluid; and
at least one acoustic receiver acoustically coupled to an exterior surface of the outer cylinder.
2. The cement bond test cell of claim 1 , further comprising an electrical feedthrough that connects the acoustic transmitter to an activation device disposed outside of the cement bond test cell.
3. The cement bond test cell of claim 1 , further comprising an acoustic support structure coaxially disposed within the inner cylinder.
4. The cement bond test cell of claim 1 , further comprising a test cement channel that connects the annulus to a test cement reservoir through a test cement pump.
5. The cement bond test cell of claim 1 , wherein the acoustic transmitter comprises a plurality of acoustic sources, wherein each of the acoustic sources is affixed at an axial elevation along the central axis inside of the inner cylinder, and wherein each of the acoustic sources is a piezoelectric crystal.
6. The cement bond test cell of claim 1 , wherein the at least one acoustic receiver comprises a plurality of acoustic detectors, wherein the plurality of acoustic detectors form a coplanar acoustic detector array, wherein each acoustic detector is disposed at an azimuthal interval around a circumference of the outer cylinder, and wherein the coplanar acoustic detector array is placed at an elevation coincident with an axial elevation of the acoustic transmitter.
7. The cement bond test cell of claim 1 , further comprising a fluid pressure channel, wherein the fluid is configured to be pressurized through the fluid pressure channel.
8. A method, comprising:
installing a cement bond test cell into a test chamber configured to apply a stress in the cement bond test cell;
filling an annulus between an outer cylinder and an inner cylinder of the cement bond test cell with a test cement;
applying a stress to the cement bond test cell;
emitting a plurality of acoustic signals from an acoustic transmitter disposed in a fluid filling the inner cylinder over a period of time;
detecting each acoustic signal using an acoustic receiver acoustically coupled to an exterior surface of the outer cylinder over the period of time;
determining a characteristic of each detected acoustic signal;
detecting a commencement of a cement bond failure based, at least in part, on the characteristic of each of the detected acoustic signals; and
determining a shear bond strength based, at least in part, on a measured axial stress at the commencement of the cement bond failure.
9. The method of claim 8 , wherein the characteristic is an acoustic travel time or an acoustic amplitude.
10. The method of claim 8 , wherein the period of time is a duration of time that coincides with a curing of the cement and the commencement of the cement bond failure.
11. The method of claim 8 , further comprising determining a calibrated relationship between a curing effect of the test cement and the characteristic.
12. The method of claim 8 , further comprising:
selecting a composition of a cement based, at least in part, on the shear bond strength of the test cement;
mixing the cement; and
pumping the cement into an annular space between a casing and a wellbore.
13. A method, comprising:
installing a cement bond test cell into a test chamber configured to apply a stress in the cement bond test cell;
filling an annulus between an outer cylinder and an inner cylinder of the cement bond test cell with a test cement;
applying a stress to the cement bond test cell;
emitting a plurality of acoustic signals from an acoustic transmitter disposed in a fluid filling the inner cylinder over a period of time;
detecting each acoustic signal using an acoustic receiver acoustically coupled to an exterior surface of the outer cylinder over the period of time;
determining a characteristic of each detected acoustic signal; and
determining a density profile of the test cement at an instant in time based, at least in part, on the characteristic.
14. The method of claim 13 , further comprising compiling a 4D settling density profile based on a plurality of density profiles determined at a plurality of instants in time.
15. The method of claim 13 , wherein the characteristic is an acoustic travel time or an acoustic amplitude.
16. The method of claim 13 , wherein the period of time is a duration of time that coincides with a curing of the cement.
17. The method of claim 13 , further comprising determining a calibrated relationship between a curing effect of the test cement and the characteristic.
18. The method of claim 13 , further comprising:
selecting a composition of a cement based, at least in part, on the settling density profile of the test cement;
mixing the cement; and
pumping the cement into an annular space between a casing and a wellbore.
19. A system, comprising:
a testing system comprising a test chamber configured to apply a stress in the test chamber;
a cement bond test cell configured to be installed in the test chamber, wherein the testing system is configured to apply a stress to the cement bond test cell, and wherein the cement bond test cell comprises:
an outer cylinder,
an inner cylinder coaxially disposed within the outer cylinder, wherein the inner cylinder defines an inner volume configured to be filled with a fluid, and wherein an annulus is formed between the outer cylinder and the inner cylinder and configured to be filled with a cement,
an acoustic transmitter disposed within the inner volume of the inner cylinder and configured to be acoustically coupled to an interior surface of the inner cylinder by the fluid, and
an acoustic receiver acoustically coupled to an exterior surface of the outer cylinder; and
a computer processor configured to:
control the stress applied by the testing system in the test chamber,
activate the acoustic transmitter over a period of time,
record an acoustic signal detected by the acoustic receiver over the period of time,
determine a characteristic of the acoustic signal,
determine a density profile of the test cement at an instant in time based, at least in part, on the characteristic,
detect a commencement of a cement bond failure based, at least in part, on the characteristic of the acoustic signal detected by the acoustic receiver, and
determine a shear bond strength based, at least in part, on a measured axial stress at the commencement of the cement bond failure.
20. The system according to claim 19 , further comprising:
a cement mixing system to mix a cement based, at least in part, on one of the shear bond strength or the density profile; and
a cement pumping system to pump the cement into an annulus between an exterior surface of a casing and a wellbore.