The effect of liquid phase on non-Darcy gas flow through proppant packs has been characterized by correcting the non-Darcy flow Forchheimer coefficient as a function of liquid saturation in the proppant pack in the past. Through an extensive experimental study it is found that at high liquid saturation, Forchheimer correlation does not hold anymore. A non-linear relationship appears that can not be characterized by factor alone. Tests are focused on the investigation of the effect of proppant properties (permeability and porosity), liquid properties (density and viscosity), and gas properties (density and viscosity) on the non-Darcy, two phase flow behavior. An empirical model that uses the liquid to gas ratio to predict the effective permeability or conductivity of a proppant pack under two phase, non-Darcy flow conditions is discussed in the paper.
Based on the fact that proppant packs have relatively narrow pore size distributions, a simplified physical model has been developed to represent two phase (liquid and gas), non-Darcy flow through proppant packs. The purpose of developing the model is to understand the effect of gas flow on the velocity of liquid in a two-phase flow process. As a result, the model can calculate a mobile liquid saturation corresponding to each combination of gas-liquid flow rate. The relative permeability of a proppant pack at different conditions can then be calculated taking both non-Darcy and two phase flow effect into account.
Author(s): Jin, Penny, G.S., STIM-LAB, Inc., L.
Paper Number: SPE 49248