Abstract

Hydrocarbon gas has gained an increasingly larger market demand these past few years. As significant numbers of gas reservoirs behave as condensate reservoirs, accurate reservoir simulation such as compositional simulation is needed to assist a decision maker to determine the best future field performance predictions. Its accuracy for gas condensate or volatile oil simulation has been proven; however, it is not widely used in the oil and gas industries because it needs a large computer storage capacity and long calculation time. The calculation time and computer storage capacity are influenced by the quantity of grid blocks used to represent a reservoir and also how many hydrocarbon and non-hydrocarbon components are used in the reservoir fluids model. One of the alternatives to reduce the calculation time is by lumping some pure components into a reduced number of pseudo components by using an accurate lumping procedure and mixing rules.

Three gas condensate samples and a hypothetical reservoir model were used to simulate a gas condensate reservoir production and evaluate the effect of Hong's lumping procedure and mixing rules on simulation calculation accuracy.

A reasonable match of simulation results is observed between lumped and non-lumped reservoir fluids and the average calculation time has been reduced by 25.34%. The required computer storage capacity was also reduced. It was observed that the reduction of calculation time with lumping procedure will be higher as the complexity of grid blocks used to represent reservoir in the simulation increases.