Gas Lift Dynamic Simulation for Unconventional Wells in the Permian Basin

Abstract

Unconventional wells in Permian Basin experience a lot of unstable flow conditions (such as slugging or heading and unloading difficulty). This paper intends to investigate the application of dynamic simulation to dissect the intricacies of gas lift unloading and instabilities in unconventional wells. The present study aims to apply these methodologies to gain deeper insights into the gas lift unloading procedure in unconventional oil wells. This study integrates gas-lift dynamic simulation with unconventional wells reservoir inflow performance relationship (IPR). This is to consider the tubing and casing interaction through the gas lift valves (GLVs) in a way of transient modeling of multi-phase flow to understand the unloading and unstable processes. The results can be used to verify whether the flow will be stable or not, and whether the injection mode will be single point or multi-point, as well as to find mitigation methods for unstable operation. Case studies of actual data with dynamic gas lift simulation are presented in this paper. The gas lift unloading process and the steady-state assumption used in gas lift design are carefully studied with the input of unconventional IPR including productivity index (PI) and static bottomhole pressure (SBHP). The results are compared against the permanent downhole gauge (PDHG) and other OSI PI data for verification. The unstable gas lift wells can be diagnosed for trouble shooting and mitigation. Gas lift valve (GLV) performance model is combined by tuning to the valve performance clearinghouse (VPC) database for valve throttling behavior. Per the authors’ knowledge, this is the first study to apply dynamic simulation to unconventional gas lift wells. This research extends the findings of Tang et al. (1999) to unconventional wells gas lift systems.