2012 Volume 128 Issue 4_5 Pages 198-208
We developed a novel two-phase micro flow meter for high-precision unsteady-state measurement of relative permeability, which is one of the most important parameter to forecast the gas injection production processes.
The flow meter consists of a small clear tube and several beam sensors that can distinguish gas and liquid. Two-phase mixture coming from a core is led to the tube and separated gas-liquid two-phase flows through the tube. Transit time of a phase through between the two beam sensors can be calculated by cross correlation analyses of signal waveforms outputted from receivers of the beam sensors that were installed beside the tube.
Components of the flow meter such as the sensor type, distance between the sensors, and inner diameter of the tube were optimized to improve the flow meter accuracy. The results suggested that the transmissive-type beam sensors should be installed in a distance that the gas/liquid boundary could transit within 2.3 seconds beside the tube whose inner diameter should be the smallest and also larger than the beam diameter.
Gas-water relative permeability in water-saturated sandstone cores was measured using both the conventional flow meter and the flow meter developed in this study. Flow meter developed in this study could measure precisely two-phase relative permeability in both a Berea sandstone core and a Kimachi sandstone core whose absolute permeability was high (4.0×10-14 m2) and low (4.0×10-16 m2) respectively while the conventional flow meter could measure that in the Berea sandstone core but the Kimachi sandstone core. These results indicate that the flow meter developed in this study is useful to measure precisely the relative permeability in not only standard sandstone cores but also extremely low permeability cores and the cores including fractures such as coal.