EOS tuning to model full field crude oil properties using multiple well fluid PVT analysis

Equations of State (EOS) are increasingly being used to model fluid properties of crude oil and gas reservoirs. This technique offers the advantage of an improved fluid property prediction over conventional black oil models. Once the crude oil or condensate fluid system has been probably characterized, its PVT behavior under a variety of conditions can easily be studied. This description is then used, within a compositional simulator, to study and choose among different scenarios for EOR schemes, such as miscible gas injection for oil reservoirs or liquid recovery under lean gas injection for condensate reservoirs. In this paper, crude oil from a reservoir in the United Arab Emirates (UAE) was characterized using the Peng–Robinson Equation of State (PR-EOS) to arrive at one EOS model that accurately describes the PVT behavior of crude oil produced from the different wells in the reservoir. The multi-sample characterization method is used to arrive at one consistent model for crude oil for the whole reservoir. The fluid samples are first analyzed for consistency to make sure that they are representative of oil produced, and then they are used to obtain parameters for EOS model. The tuning procedure for the EOS is done systematically by matching the volumetric and phase behavior results with laboratory results. Also, a consistent C7+ pseudo-component split using the Whitson splitting method is used for all samples to arrive at a consistent model for crude oil for the whole reservoir. Results showed a very good match of PVT properties predicted using the EOS model with laboratory tests for this field. These results demonstrate the usefulness of the multi-sample method in providing one EOS model for the crude oil using PVT test results from different wells. The EOS model developed for this particular field may be used in reservoir simulation studies to optimize hydrocarbon recovery.