Application of Stream-Conversion Methods To Generate Compositional Streams From the Results of a Multimillion-Cell Black-Oil-Simulation Study of the Shaybah Field

Abstract

Detailed compositional simulation of a giant reservoir with many components is not practical. However, detailed multimillion cell black oil simulation of giant reservoirs is now quite feasible. In this work we apply an efficient method to generate the compositional rates from a black oil simulation of the giant Shaybah field. In situations where the reservoir recovery mechanism is not dominated by compositional effects, an Equation of State (EOS) based stream conversion method can be used. This stream conversion method relies on the fact that when laboratory PVT data measured on available well stream compositions are used to generate the black oil PVT tables, some of the compositional information is lost. The stream conversion model retains this valuable compositional information and applies it to each producing well completion in the black oil simulation at every time step. As proof of concept, the stream conversion method was applied to a black oil simulation and to a limited (eightcomponent) compositional simulation to generate a 17component compositional stream and the results were compared to the respective full EOS compositional simulation for a relatively small sector (250,000 cells) of the giant Shaybah field. The compositional stream rates are in excellent agreement with the stream converted black oil results. As would be expected, the computational costs of using the EOS based compositional simulator (with 17 components) is in excess of 40 times the black oil simulation time for the small sector model. In general, the stream conversion method can be used to generate the dynamically varying compositional streams from any black oil simulation for use in the design and operation of surface facilities and in calculating the amounts of a certain cut (e.g. NGL) from the production streams.