Time/amplitude domain reflectometry as a technique for measurement of surface wettability
A surface wettability measurement method for determining the surface wettability of a surface for operations that require the removal of oil-based fluid such as cementing operations in an oil/gas environment. Time domain reflectometry (TDR) measurements are used to measure the wettability in a wellbore downhole during operations or in a lab environment when fluid flow is present. A surface wettability measurement system for determining the surface wettability of a surface located either in a wellbore downhole or in a laboratory setting using time domain reflectometry for measurements during operations when fluid flow is present.
1. A surface wettability measurement method comprising:
providing first and second electrodes on a surface, said electrodes electrically insulated from each other;
coating the surface with a first fluid;
displacing the first fluid off of the surface using a second fluid;
at least once during or after said displacing, sending an electrical pulse to the first and second electrodes and measuring the reflected pulse using time domain reflectometry (TDR) techniques; and
determining, based on the reflected pulse, whether the surface has been wetted by the second fluid.
2. The method of claim 1 , further comprising ceasing said displacing in response to determining that the surface has been wetted.
3. The method of claim 1 , further comprising increasing the fluid flow rate of the second fluid in response to determining that the surface has not been wetted.
4. The method of claim 1 , further comprising adjusting an attribute of the second fluid in response to determining that the surface has not been wetted.
5. The method of claim 1 , further comprising selecting or updating a displacement time interval in response to determining that the surface has been wetted.
6. The method according to any one of claims 1 - 5 , further comprising commencing cementing operations in response to determining that the surface has been wetted.
7. The method of claim 1 , wherein the first fluid is oil-based.
8. The method of claim 1 , wherein the second fluid is water-based.
9. The method of claim 1 , wherein the surface is part of a surface wettability test apparatus located at the earth's surface.
10. The method of claim 1 , wherein the surface is an exterior surface of a casing deployed downhole in a wellbore.
11. A surface wettability measurement system, comprising:
a first and second electrode integrated with a surface, said electrodes electrically insulated from each other;
a signal generator; and
a time domain reflectometry (TDR) controller coupled to the first and second electrodes, wherein the TDR controller obtains a TDR measurement while or after a displacing fluid moves over a surface, wherein the TDR measurement indicates a surface wettability of the surface.
12. The system of claim 11 , wherein the first and second electrodes are positioned along an outside surface of a casing in a downhole environment.
13. The system of claim 11 , further comprising a plurality of electrode pairs positioned along an outside surface of a casing in a downhole environment to enable wettability measurements at multiple positions along the outside surface of the casing.
14. The system of claim 11 , wherein the surface is a component of a surface wettability test apparatus located at earth's surface.
15. The system of claim 14 , wherein the test apparatus further includes a rotating bob to cause the displacing fluid to flow across the surface.
16. The system of claim 14 , wherein the test apparatus further includes a rotating container to cause the displacing fluid to flow across the surface.
17. The system of claim 14 , wherein the test apparatus further includes at least one fluid pump to cause the displacing fluid to flow across the surface.
18. The system of claim 14 , further comprising a cementing controller that initiates a cementing operation in response to the TDR measurement indicating that the surface has been wetted.