This paper describes the approach taken to evaluate and successfully treat flow assurance challenges associated to high viscosity produced fluids in an oil producing field, offshore Gulf of Mexico.
The first section of the paper outlines primary evaluation criteria: discussing base line modeling of crude oil characteristics at various points of the production system, laboratory analyses, detailed explanation of the chemistries considered for reducing the viscosity, and the strategy to remediate multiple flow assurance challenges with subsequent performance testing. The second section presents field trial data from the application of the selected flow improver and its longer-term performance.
Initial evaluation of high viscosity was required due to deposition of asphaltene, high levels of emulsion, increased pressure and resultant decrease in production All of these production issues caused increased spending on fluids treatment in a field that is mature and becoming more marginal to produce. Initial analysis of the produced fluid did not result in an immediate, clear approach to address the concern, without considering the multiple factors that can contribute to flow assurance challenges. Organic deposition, such as waxes and asphaltenes, were found to increase fluid viscosity and worsen highly stabilized emulsions. Crude oil/water emulsions also cause increased viscosity and needed to be addressed as part of any holistic solution. Each issue was studied and experimented on its own and in combination to ensure there was no reductive effect in a final chemical application that needed to treat them all.
Successful field application of the selected flow improver technology exceeded the performance at laboratory scale achieving over 30% reduction in total fluid viscosity over long-term field deployment with associated benefits to the offshore operator which will be elaborated further in this paper. As an outcome of this field trial, this paper also presents a proposed generic approach in devising chemical solutions for treatment of high viscosity fluids.