Increasing Production Through the Application of an Emulsion Viscosity Reducer in an Onshore Gas Lifted Middle East Oil Field

Abstract

Viscous emulsions are produced as oil and water are transported from the reservoir through the production infrastructure as a result of the shear forces exerted on the fluids by process restrictions. As fields mature and water cuts in wells increase so does the viscosity of the produced fluids due to the formation of emulsions. This increase in viscosity results in an increase in frictional forces and can lead to slugging and a reduction in production. Laboratory testing was performed on fresh samples collected in the field to identify suitable Emulsion Viscosity Reducer chemistry by measuring the reduction in emulsion viscosity with the addition of various chemical formulations. Based on the results of this testing a field trial was performed on three wells, applying the selected formulation downhole via injection through the gas lift system. Gas lift compatibility testing was performed on the chemical prior to the trial. Gas lift injection was demonstrated as a viable means in which to inject Emulsion Viscosity Reducer chemical downhole. A lag of between 12 and 24 hours was observed between chemical injection commencing and changes in the fluids being produced being observed. Emulsion was measured by centrifugal analysis and viscosity using a viscosity cup. Measurements were taken prior to chemical injection commencing and throughout the duration of the trial. The chemical injection was optimised and the effect on emulsion and viscosity observed. Reductions in viscosity of approximately 50% were achieved on each well. Emulsion content was also significantly reduced although some wells displayed more erratic results than others, indicating that slugging was a factor influencing emulsion stability. Oil production was also recorded, and increases observed with up to 10% more oil on average produced during the trial period compared to baseline data. These reductions in viscosity and emulsion, and subsequent increase in oil production, show that existing artificial lift infrastructure can be utilised to increase production efficiency, opening the possibility for other producers of oil and gas in the region to maximise their existing their assets as water cuts increase.