Computational and experimental studies of unstable isothermal filtration of methane–n-pentane gas-condensate mixture

Abstract

During the operation of gas-condensate fields, reservoir pressure gradually decreases. When the pressure drops below the dew point, a retrograde fluid with low mobility is formed, which significantly reduces the well flow rate. Under certain conditions (pressure drop, yield point of the liquid phase, and absolute permeability of the reservoir), unstable filtration modes may occur, including those that block fluid flow. Determination of these conditions is necessary for planning a gas-condensate production strategy and developing methods for influencing the reservoir system to increase the flow rate of valuable hydrocarbon feedstock.This paper presents the results of computational and experimental studies of the isothermal filtration process of a model methane–n-pentane mixture in a porous medium. The studies were carried out on a linear bulk reservoir model at supercritical inlet pressures and variations in the composition of the supplied mixture and pressure at the model outlet. As a result of numerical and laboratory experiments, it was shown that there is a region of parameters (composition of the mixture, pressure drop, and yield point of the liquid phase) in which flow modes can be unstable, including those with periodic blocking of the fluid flow. The conditions for the appearance of unstable flow modes are discussed.