Subsea processing has been considered a potential technology to anticipate and to increment oil production in deep water fields. The key element to achieve this is to increase pressure drawdown by reducing the backpressure imposed by the system. It can be defined as any treatment of the produced fluids performed on the seabed. Among the available technologies, Subsea Gas-Liquid Separation is the most advanced one for deep water applications. The most recommended way to estimate incremental oil recovery and to compare with other artificial lift technologies is through Integrated Production Modeling, which integrates reservoir, production and processing facility models.
The motivation of the present work is the need to quantify the incremental oil recovery achieved through subsea processing and the objective is to evaluate the possible advantages of using subsea gas-liquid separation as the main artificial lift method of a reservoir with similar characteristics observed in the recent discoveries in Brazil, comparing its performance with one of the most traditional lift technologies: gas lift.
The comparison is performed in two case studies. In the first one, a homogeneous reservoir model is used to focus the comparison in the artificial lift technologies. In the second case study, a heterogeneous reservoir model is used to evaluate the performance in a more realistic reservoir.
The results show that reservoir pressure maintenance is a key element to extract all benefits related to this subsea technology. A combination of technology (subsea gas-liquid separation and gas lift) also shows that it is possible to increment the oil production in a mature phase of the field. However, that it is not the same as changing the artificial lift technology. One of the benefits of subsea gas-liquid separation is that it is possible to produce the same oil quantity, compared to gas lift, with a smaller tubing and pipeline diameter.