Liquid loading is often a problem for mature gas wells due to declining reservoir energy. It is the inability of a producing gas to remove its coproduced liquids from the wellbore. Due to declining reservoir energy, the liquid starts to accumulate in the the well leading to a change in the fluid flow regime from annular two-phase flow to churn (or slug) flow. This transition from annular to churn or slug flow initiates the process of liquid loading. Currently, liquid loading is predominantly premised on diagnosing the problem at the wellhead-flow conditions. This study reveals that the problem may start well in advance of its effects being felt at the wellhead.
The remedial efforts needed to keep the well flowing are severely impacted by the stage at which liquid loading is diagnosed. Earlier diagnosis with the help of proposed coupled wellbore-reservoir modeling can prove instrumental in cutting costs of remediation. To this effect, the study also presents a model for the design of plunger lift for such wells. The model allows for an efficient design of plunger lift by incorporating physics of fluid flow in the wellbore. Because the dimensions and trajectory of the wellbore have such profound impact on the operability of plunger lift, operators can use this model by just providing the known input parameters to determine the design variables, target casing pressure and duration for the plunger cycle.
Contributors: Aldousari, M.; Hashmi, G. M.; Tamim, N.; Akter, F.; A. R. Hasan.
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