Comprehensive Gas Reservoir and Wellbore Coupled Model to Study Liquid Loading
[Thesis]
Aldousari, Mohammad F. K.H. O. K.H.
Zhu, Ding
Texas A&M University
2019
108
Ph.D.
Texas A&M University
2019
Simulating gas flow from the reservoir to the wellhead is a complicated task often done by a commercial software or overlay simplified coupled model based on one inflow equation. The commercial software requires specialized training as they are cumbersome and time-consuming. Besides, they cannot be modified to accommodate any research idea requiring additional or different approaches. In this study, a simple, comprehensive reservoir-wellbore coupled model is presented to be used by researchers or engineers in the field where the access to fully fledged simulation is unavailable. The proposed model consists of two systems. The wellbore system depends on a two-phase mechanistic model to calculate all fluid properties and pressure drop along the wellbore. The reservoir system relies on Darcy flow equations and relative permeability correlations to estimate the inflow flow rate for each phase. Finally, gas reservoir material balance is used to obtain reservoir pressure for every time step. This model is implicit and dynamic. After validating the model with field data and commercial software, several case studies were created to investigate gas well related issues. The proposed models can investigate the liquid loading phenomena where the gas is unable to lift the liquid droplets to the surface. The model can predicate the onset of the liquid loading and the time needed for liquid to kill the well by examining wellbore fluid changes throughout the wellbore. The transition of flow pattern from annular to churn flow is considered the initiation of this phenomena. The model can present a visual picture of flow pattern changes through the well's life. Using the proposed model as a diagnostic tool, Hasan-Kabir model has been modified by introducing smoothing flow pattern transition equations.