Research on thermal mass flowmeter (TMF) measurement of coalbed methane (CBM) well production profile

Developing coalbed methane (CBM) aligns with global climate change policies and sustainable energy development. Currently, methods for testing gas and water production profiles in CBM wells are diverse. A downhole constant-flow thermal mass flowmeter (TMF) was designed to address the difficulty of testing gas production above the liquid level in low-yield CBM wells. A computational fluid dynamics model with a 125 mm diameter pipe was established to study the TMF’s temperature field and thermal equilibrium time as the gas flow rate changes. The relationship curve between temperature, thermal equilibrium time, and flow rate changes was obtained. The effect of the TMF’s installation angle and position in the wellbore on resolution was discussed. Experimental research on a multiphase flow simulation apparatus showed that the TMF has good response capability and testing accuracy in a gas environment. Measuring downhole flow rates using the thermal flow meters is feasible and meets the testing requirements of CBM wells.