Evaluating Methods of Obtaining Original Composition in Oil Reservoirs

The purpose of sampling is to obtain a representative sample identical to the initial reservoir fluid. This condition is enormously necessary because reservoirengineering studies are performed using PVT analysis data on the basis of the reservoir at its initial conditions. Consequently, samples should ideally betaken in virgin reservoirs or in new wells completed in undepleted zones. However, if sampling cannot be performed at initial conditions, or if samples have tobe taken in a well that has previously produced a large amount of oil, non-representative samples might be collected. Preparing accurate original fluidfrom non-representative samples would be a masterpiece. Therefore this study focuses on detecting the most accurate method of preparingoriginal compositions of oil reservoirs from nonrepresentative samples. For this purpose recombination as ordinary method and Equilibrium-Contact-Mixing (ECM) as unusual and not yet been applicable method are contrasted by using real PVT data. Compositional simulation and Equation of State(EOS) characterization are used for modeling in this paper. The evaluation concludes that ECM method is the most accurate method of preparing original composition of oil reservoirs.