Numerical simulation and parameter optimization of downhole stratified flow measurement with CO2 injection

The density and viscosity of supercritical CO
2
are obviously affected by wellbore temperature and pressure. In order to provide the accuracy of downhole stratified injection CO
2
flow measurement, this paper constructs the downhole CO
2
flow metering nozzle model, first calculates the wellbore temperature and pressure field to obtain CO
2
density, phase state and other parameters, and then uses Fluent to simulate the relationship between differential pressure and injection pressure under different temperature and pressure to get the flow metering model. At the same time, in order to improve the pressure accuracy of the nozzle, the parameters of the pressure port position are optimized to obtain the best pressure outlet position. The results show that when the wellhead injection pressure increases to a certain extent, the injection pressure has little effect on the differential pressure, mainly because the density of supercritical CO
2
no longer changes greatly with the increase of injection pressure, which provides a reference for the wellhead injection pressure of downhole stratified injection CO
2
. The existing nozzle Flowmeter structure can meet the requirements of pressure extraction position for downhole CO
2
measurement. This study has certain practical significance for improving the test performance of nozzle Flowmeter and CO
2
layered measurement and control.