Design of a High-Pressure Research Flow Loop for the Experimental Investigation of Liquid Loading in Gas Wells

Abstract

AbstractExisting models to predict and analyze liquid loading in gas wells are based on steady-state flow. Even when transient multiphase wellbore models are employed, steady-state or pseudo steady-state inflow performance relationships are used to characterize the reservoir. A more reliable approach consists of modeling the dynamics in the near-wellbore region with its transient boundary conditions for the wellbore. The development of new models to mimic the dynamic interaction between reservoir and wellbore requires a purpose-built flow loop. We have developed a design to construct such a facility.This new facility will be the first to integrate pipe representing the wellbore with a porous medium that will fully mimic the formation surrounding the wellbore. This design will account not only for flow into the wellbore, but any reverse flow from the pipe into the medium.We used integrated wellbore/reservoir system analysis to screen the parameters required to recreate liquid loading under laboratory conditions. Our results suggested using a compressed air system with a discharge pressure between 470 to 650 psi with gas rates of 400 to 650 scf/m along with water injected at a rate of 100 gpm. Once the range in operating conditions was defined, the equipment and mechanical components for the facility were selected and designed.Our results showed that three reciprocating compressors working in parallel provide the smallest, most economic, and most flexible configuration for the TowerLab facility at Texas A&M University. The design of the pressure vessel hosting the porous medium will require a cylindrical body with top- and bottom-welded flathead covers with multiple openings to minimize weight. The required superficial velocities for air and water indicate that the system will need independent injection into the porous medium through two manifolds. Optimally, the system will use digital pressure gauges, coriolis or vortex technology to measure air flow and turbine meters for water flow.The new facility will significantly improve our ability to mimic the physics of multiple phase flow for the development of liquid loading models and lead to better optimization of gas fields.