Development and application of fluid characterization algorithms to obtain an accurate description of a PVT model for Kazakhstani oil

Abstract

Compositional reservoir modeling often requires a large number of instantaneous calculations. To reduce the dimension of the problem and the amount of computation, several components are usually grouped into pseudo-components. However, to model surface processes, it is important to have a detailed phase composition. Accurate fluid composition requires laboratory analysis, which is costly and time-consuming. This study addresses this issue by introducing an advanced delumping procedure aimed at providing an accurate fluid characterization. The primary objective was to develop a sophisticated delumping procedure capable of precisely describing detailed fluid compositions from calculations involving mixtures. Its goal is to reduce reliance on laboratory analysis, making the process more efficient. The results obtained from this research can improve the planning and modeling of surface facilities, developed under conditions of reservoir pressure above saturation pressure. To test the effectiveness of the proposed delumping and achieve the goals set, experiments were carried out on compositional simulation of oil production in the Caspian basin. The procedure uses reduction parameters calculated from simulation data and an analytical approach to characterize fluid compositions from the original data. Detailed fluid compositions obtained through laboratory PVT analysis were then compared with the results of simulation using PVTsim software and numerical delumping procedures. The findings showed a close agreement between the outcomes of detailed compositions obtained through the delumping procedure and of laboratory analysis, with an average deviation less than 5 %, confirming the effectiveness of delumping as an alternative method for obtaining an accurate fluid composition