Fluid component determination using thermal properties

A method comprising:

• measuring a temperature of a fluid flowing through a completion string downhole in a well via a first thermal detector, the first thermal detector comprising a passive temperature sensor and configured to measure a reference temperature;
• heating a resistive element of a thermal detector at a position along the completion string downhole in the well by applying power to the resistive element, the thermal detector located downstream of the first thermal detector, wherein heat from the resistive element is transmitted to the fluid flowing by the position;
• determining, via the thermal detector, a flow velocity of the fluid through the completion string and multiple thermal properties of the fluid, the multiple thermal properties of the fluid comprising thermal conductivity and thermal diffusivity of the fluid;
• using the determined flow velocity and the multiple thermal properties to determine phase fractions of the fluid;
• and
• controlling at least one inflow control valve of the completion string based on the determined phase fractions of the fluid.