Measuring a water cut of hydrocarbon fluid in a production pipe

A method for measuring water cut in fluid, comprising:

• transmitting a microwave through a first waveguide attached to a production pipe through which a fluid flows, wherein the microwave is directed at the fluid, and wherein the first waveguide uses a first filling material;
• using measurement results based on reflection or propagation of the microwave, determining that a water cut of the fluid is within a particular water cut range;
• after transmitting the microwave through the first waveguide and determining that the water cut of the fluid is within the particular water cut range, replacing the first waveguide with a second waveguide, wherein the second waveguide uses a second filling material that is different than the first filling material;
• transmitting a second microwave through the second waveguide, wherein the second microwave is directed to the fluid in the production pipe;
• and
• obtaining second measurement results based on the second microwave.

A water cut measuring system, comprising:

• a first waveguide attached to a production pipe at a first location, wherein the first waveguide is configured to direct microwaves to fluids in the production pipe, wherein the first waveguide is filled with a first filling material comprising electrical properties affecting transmission of the microwave to the fluids;
• a second waveguide attached to the production pipe at a second location upstream or downstream of the first location, wherein the second waveguide is configured to direct microwaves to the fluids in the production pipe, wherein the second waveguide is filled with a second filling material that is different than the first filling material;
• a network analyzer connected with the first waveguide and the second waveguide, wherein the network analyzer is configured to:
• transmit microwaves to the first waveguide and the second waveguide;
• receive microwaves reflected from the fluid or propagated through the fluids;
• and
• obtain measurement results based on the reflected or propagated microwave,
• wherein the measurement results are used to determine a water cut of the fluid;
• and
• a controller communicatively coupled with the network analyzer, wherein the controller comprises:
• a memory;
• and
• at least one hardware processor communicatively coupled with the memory and configured to determine a water cut of the fluid based on the measurement results,
• wherein the at least one hardware processor configured to determine that the water cut is within a particular water cut range;
• and
• in response to determining that the water cut is within a particular water cut range, determine a second water cut of the fluid using the second waveguide.