Application of IOR technology to a heavy-oil reservoir in the cold production

Abstract

A heavy oil field located in North Sea, United Kingdom (UK) was discovered in 1981. However, the field has not been developed due to a high oil viscosity, low oil API gravity (12 to 14°API) and an uncertainty of reservoir extent. Nevertheless, based on the reinterpretation of an old 3D seismic data and by acquiring a high resolution 3D seismic data, a full-field development plan, which was applied with water flooding with a horizontal or highly deviated well, and an Electrical Submersible Pump (ESP) completion with diluent injection as an optimal artificial lift, was prepared and then the project was sanctioned.
In addition, as investigating the upside recovery potential, the screening study of enhanced oil recovery (EOR) was conducted. For the heavy oil field, steam injection or immiscible gas injection was considered as the possible effective EOR method. However, considering the offshore field location, a reservoir temperature (40 to 50 °C) and a salinity of formation water, polymer flooding was considered to be the most appropriate method. Accordingly, an analytical and a numerical simulation study were carried out in order to estimate oil increment when applying polymer flooding and that was compared with the water flooding application to assess EOR process. Sensitivity study to confirm the impact of polymer property on oil recovery was also conducted.