EOR Screening for the Rijn Oil Field by Numerical Simulation

A screening study and subsequent dynamic simulation of selected Enhanced Oil Recovery (EOR) methods for the Rijn oil field are presented. The objective of the study was to obtain insight in the EOR potential of the Rijn field. The Rijn oil field, located in block P15 in the Dutch sector of the North Sea Continental Shelf, produced 24MMSTB oil cumulative (RF= 12-18%) by water flooding and gas lift from 1986 until 1998 and was re-developed in 2010, using electrical submersible pumps (ESP’s), expecting another 3.5MMSTB (expected RF= 21%). In general an EOR method has to address certain reservoir characteristics such as heterogeneity, remaining oil saturation and residual oil saturation. For the Rijn oil field the presence of a thief zone, extensive water cycling, the offshore location and a relatively short remaining field life were also important factors taken into account when making a selection. From the screening study polymer flooding, surfactant flooding and in-depth conformance control (by BrightWater\u99) were selected for investigation by numerical simulations. Other techniques such as solvent, microbial and thermally enhanced recovery methods were discarded based on the field characteristics. Numerical modelling was done on a detailed sector model of the Rijn field with a refined grid, instead of using a conceptual simulation model. This was done to incorporate realistic reservoir and geological conditions. Polymer flooding showed disappointing production responses mainly caused by injectivity issues due to increased viscosity of the injected fluid. In-depth conformance control using BrightWater\u99 did not increase recovery because the poor reservoir quality in the modelled reservoir sector. A simulation run, where the high permeable thief zone was blocked, displayed a decrease in water cut but also a decrease in oil production. It is expected that better results could be obtained when the method is applied to better quality parts of the reservoir. The EOR method with the best response was surfactant flooding. Adding surfactant to the injection water showed 12% increase in oil recovery. The results presented form a basis for further investigation of surfactant systems for applications in the Rijn oil field.Section Petroleum EngineeringCivil Engineering and Geoscience