Optical multiphase flowmeter

A method of measuring flow of a fluid mixture in a conduit, comprising:

• transmitting light into the fluid mixture;
• detecting light interactions with the fluid mixture at first and second locations along the conduit, wherein the first location is separated by a distance in a direction of flow through the conduit from the second location, wherein the light is transmitted into the fluid mixture on a same side of the conduit as the first and second locations, and wherein the light interactions detected at the first and second locations are a measure of reflectance of the light transmitted into the fluid mixture;
• and
• processing first and second time-varying signals of the light interactions detected at the first and second locations, respectively, wherein the processing determines phase velocity of at least one phase within the fluid mixture.

A method of measuring flow of a fluid mixture in a conduit, comprising:

• transmitting light into the fluid mixture;
• measuring light interactions at first and second locations along the conduit to detect a time delay in interactions detected at the first location and then the second, wherein the light is transmitted into the fluid mixture on a same side of the conduit as the first and second locations and wherein the light interactions detected are a measure of reflectance of light transmitted into the fluid mixture;
• and
• calculating a velocity of flow within the fluid mixture based on the time delay.