Abstract
Cubic Equations of State are a set of simple mathematical expressions that are used to model the phase and volumetric behavior of reservoir fluids. These simple expressions cannot be used directly as predictive models due to their characteristic lacks in estimating liquid density and the uncertainties in defining critical properties of the fluid related pseudo-components. The standard approach as well as the industry common practice to overcoming these deficiencies are to “Tune” the selected equation of state adjustable parameters to match the fluid available experimental PVT data. The optimum values of the selected regressing components parameters are obtained by minimizing an error function as defined by the difference between the predicted EOS PVT data and the lab measured PVT values. It should be pointed out that the EOS model tuning is a multi-stage process that must be effectively applied to reduce the substantial numbers of the EOS undefined parameters and numbers of compositional pseudo-components down to a manageable set of variables. This task is challenging since there are many potential tuning parameters; thus, leading to various tuning results with some of questionable validity and non-unique solution.
At present; our industry, Academic world, PVT specialists, and PVT software developers have not provided with a single standardize approach for tuning equations of state, all various proposed approaches have only some common similarities in tuning EOS. Due to the complicated nature of hydrocarbon fluids and limitations of the most commonly used equations of state; not a Single Tuning Methodology is Applicable for Use in All Types of Hydrocarbon Systems.
The objective of this short seminar to present a detailed Workflow and to Highlights several Practical Recommendations for developing and exporting a tuned EOS for proper use in compositional simulators.
Short Bio
Dr. Tarek Ahmed is a former Professor of Petroleum Engineering Department at Montana Tech of the University of Montana. He joined Montana Tech in 1980 until his early retirement in 2002. During his 22 years tenure at Montana Tech. Dr. Ahmed held the Union Pacific Endowed Chair and served as the head of the petroleum engineering department for several years. After his early retirement in 2002 from Montana Tech, had held positions as a Reservoir Engineering Advisor & PVT SME with Anadarko Petroleum for 9 years, as senior engineering advisor with Baker Hughes for 2 years and as a Global Reservoir Engineering Advisor with Talisman Energy for 3 years.
Dr. Ahmed is an active member of SPE representing the society as a petroleum engineering program evaluator in several ABET accreditation visits.
Tarek is the founder of Tarek Ahmed & Associates Ltd; a consulting firm specializes in providing high quality public and in-house Petroleum Engineering courses and consulting services to the petroleum industry worldwide