Abstract
Production from gas condensate reservoir poses the major challenge of condensate banking or blockage in a gas condensate reservoir. Condensate banking reduces the relative permeability of the gas and thereby acts as a partial blockage to gas production. Condensate occurs near the wellbore as the pressure decline around the wellbore. A promising sign of condensate banking is observed in the rise of gas-oil ratio (GOR) through production and a decrease in the condensate yield of the well. It led to a considerable reduction in well deliverability and well rate for gas condensate reservoirs. Determining the well deliverability of a gas condensate reservoir and methods to optimise productivity is paramount in the industry.This research investigates the fluid phase-change behaviour in a gas condensate reservoir during depletion to determine the related problems encountered in well deliverability during condensate production. Moreover, it evaluates the optimisation techniques using relative permeability through wettability alteration to treat the reservoir from strongly liquid wet to strongly gas wet, which enhances the deliverability of gas/condensate in the reservoir.
The research utilises simulation techniques in studying the compositional changes in hydrocarbon composition over time at near well-bore and a distance from the wellbore. The work's outcome helps determine the timing of condensate blockage and its distance from the wellbore. The techniques use two geometric grid spacing schemes, global and local grid analysis, to determine the size and timing of the three common regions associated with immobile and mobile gas condensate. The study analyses the influence of absolute permeability (100 mD, 10 mD, and 1mD) and the effect of relative permeability on the wettability alteration. These procedures were applied using a single well model to evaluate the phase change tracking approach predicted.
The findings help to better understand the hydrocarbon phase change near wellbores in gas condensate reservoirs from the gas phase to condensate. The suggested approach to tracking the timing and location of condensate formation can also assist the production engineers in managing condensate production and selecting appropriate optimisation techniques to improve condensate recovery.
| Date of Award | Oct 2022 |
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| Original language | English |
| Awarding Institution |
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| Supervisor | Sina Rezaei Gomari (Supervisor), Johnson Ugwu (Supervisor) & Paul Russell (Supervisor) |