Dr. Shawket Ghedan is an associate professor of Reservoir Engineering at the Petroleum Institute. He has over 20 years of diverse academic and industrial experience. His areas of expertise include reservoir characterization and modeling including: rock typing, measurement and application of SCAL data in Reservoir Modeling, optimization for reservoir uncertainty Assessment, history matching and probabilistic forecasting, and CO2-EOR processes. He holds a B.Sc. degree in Petroleum Engineering from Baghdad University, and M.E. and Ph.D. degrees in Reservoir Engineering from the Colorado School of Mines.

Dr. Ghedan was a board director of SPE Abu Dhabi Section since 2000, and chairman of the board for 2006-2008. He was the SPE distinguished lecturer for 2005-2006. He is a member of the SPE distinguished Lecturers Selection committee since 2008-now. He is the chair of the SPE Cedric K. Ferguson Medal Committee for 2009-2010. Shawket was awarded the 2009 SPE Middle East Regional Technical Award for Distinguished Contribution to Petroleum Engineering in the area of Reservoir Description and Dynamics. Finally Dr. Ghedan is a Schlumberger-NExT Reservoir Engineering Instructor. He taught the industrial courses of PVT and EOS, Basics and Advanced Reservoir Simulation, Compositional Reservoir Simulation, Simulation of Fractured Reservoirs, and Enhanced Oil Recovery.

Abstract

Reservoir Rock Typing for Dynamic Simulation Models Shawket Ghedan
The Petroleum Institute - Abu Dhabi, UAE

In reservoir characterization studies, static reservoir rock types, SRRTs, are utilized to guide the modeling of reservoir petrophysical properties in static geological models. However, since the reservoir dynamic properties are not considered in the static rock typing schemes, the SRRTs should not be used - as being practiced now – to guide the distribution of reservoir multiphase dynamic properties of capillary pressure, Pc, and relative permeability, Kr, curves to the cells of dynamic simulation models.

Considering the rock attributes that go into any SRRTs scheme and assuming identical interfacial tension between the different reservoir fluids, this paper suggests that the dynamic reservoir rock types, DRRTs, would only be a function of wettability for any SRRT. Thus by imposing wettability on the SRRTs, reservoir engineers should be able to generate the DRRTs, the proper guide for generating and distributing Pc and Kr curves for dynamic simulation models.

This technique is applied for building the simulation model of a major carbonate oil reservoir. The gradual change of reservoir wettability from oil wet to water wet dictated the generation of many DRRTs for any SRRT, each defines SRRT at a different reservoir level between the top and the upper limit of the transition zone.

Available experimental Pc and Kr data, acquired for only few SRRTs, were utilized to develop correlations to determine the saturation and Kr endpoints of the Kr curves. The connate water saturation, Swc, of any DRRT is picked from the Pc curve of the parent SRRT at that DRRT reservoir level. Swc is correlated with the residual oil saturation, Sorw, which is used to establish the maximum water Kr point of Krwmax, bearing in mind that oil Kr maximum point, Kromax, is assumed to be 1. Furthermore, the shape of the different Kr curves would be devised by picking the corresponding Corey exponents as they are correlated with wettability for any SRRT. The consistently derived sets of Kr curves helped build a very well initialized and history matched simulation model.

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