Perpustakaan Digital ITB

Flow assurance has been a major problem in the development of a heavy oil field. It is common that this issue has a multiplier effect from the reservoir up to processing facilities, reducing productivity and in turn, increasing financial burden. A lot of major oil and gas operators in Indonesia had spent a lot of capital expenses dealing with managing complex reservoirs with severe flow assurance issues, namely high water cut, excessively viscous oil, and its effect on fluid flow. R Field, a complex oil field in Indonesia, currently produces 3000 BOPD and the recovery factor is 4% after thirty years of production. This field is characterized by extreme oil viscosity, up to 4000 cP at surface condition, which leads to high backpressure while delivering fluid to the pipeline system. This highly viscous oil creates unstable flow due to the viscosity difference between oil and water, causing unfavorable flow-pattern: slug flow to annular flow. As a result, oil and water do not arrive at the same time at receiving facilities, leading to the highly frequent occurrence of the oil-water slug phenomenon. An idea is presented in this study to reduce the occurrence of severe slugging phenomenon by performing a water blending scheme during fluid transportation. The idea is based on a hypothesis that performing forced emulsion of brine and heavy oil promotes dispersion of oil into small droplets which can be carried by injected water under relatively lower velocity. This idea is attractive since it is simple to perform, by only directing produced water from available sources such as water zones below a hydrocarbon bearing zone or reactivation of high water cut wells to the pipeline system. In order to increase the efficiency of the forced emulsion process, it is then decided to estimate the minimum acceptable water cut to develop sufficient emulsion viscosity to prevent high backpressure. Based on simulation using commercial software, the result shows that the water cut should be maintained at 80%. Less water cut will lead to high backpressure subsequently which delays the arrival time of the oil for more than one day from the water. This result infers that one of the available solutions to handle severe slugging is by modifying water cut profile during hydrocarbon transportation. This approach gives a new insight into marginal field optimization.