Integrated Wellbore/Reservoir Transient Modelling of Liquid Loading in Gas Wells

A major operational constraint in mature gas fields around the world is liquid loading. This manifests itself as an increasing back pressure on the reservoir due to a rising liquid column in the well, which initially decreases deliverability, then ultimately causes the gas well to cease production. Theoretically, every gas well will experience this debilitating phenomenon in the latter stages of its producing life. Liquid loading is a transient phenomenon that involves interaction between the wellbore and the reservoir, which implies that it plays an important role when performing gas well numerical simulation. Recent efforts to improve modelling liquid loading have led to considerable developments in this area and provided some interesting results. Limpasurat et al. (2013) introduced a novel concept of wellbore boundary condition by using an academic dynamic multiphase flow model to history match a gas well with 25 years of production history. Building on previous research, this paper presents the results of modelling the same gas well undergoing controlled flow and shut-in cycles, using commercial integrated numerical software that connects a transient wellbore model to a reservoir model. In order to evaluate the performances of different modelling methods, comparisons are made between the academic approach and the commercial approach, including whether they capture the Ushaped pressure profile originally proposed by (Zhang et al. (2010)). The paper concludes with recommendations for further developments in this research area, which would provide a better fundamental understanding of the dynamic phenomena that take place in the near well-bore region during liquid loading