Multiphase Flow Effects:
SPE 15066  |  SPE 26602  |  SPE 30494  |  SPE 49248

Realistic Fracture Conductivities of Propped Hydraulic Fractures

David Milton-Tayler, Fractech Ltd., SPE Member

This paper summarizes lab data showing the significance of dual phase flow. Effective proppant permeability was found to be reduced by a factor of 2 to 10 for typical saturations. References include a 1929 study showing similar inertial effect in curved helical tubes, confirming that non-Darcy effects are related to acceleration changes in the fluid. The author describes the nuances with measuring dual phase flow; changing flowrates will simultaneously alter the saturations. The author defines a term ”gamma” as the ratio of actual pressure drop divided by the pressure drop for single phase flow. Gamma is shown to be dependent on pore pressure - presumably due to greater density (inertia) and saturation changes. Conclusions from the paper include:

"In instances where a high level of water cut is flowing concurrently with gas, the effective permeability of the pack may be reduced by as much as an order of magnitude," and "Even in situations with very low water cut, the impact (of a liquid phase) on gas permeability is still significant, and should be considered."