Prediction of Molar Volumes of the Sudanese Reservoir Fluids

Ali A Rabah ,Sumya Abdel Moneim Mohamed

doi:10.1155/2010/142475

Abstract

This paper provided important experimental PVT data of the Sudanese reservoir fluids. It includes composition analysis of 11 mixtures and about 148 PVT data points of constant mass expansion (CME) tests at pressures below the bubble point. The datasets are compared with eight equations of state (EOS), namely, Peng Robinson (PR), Soave-Redlich-Kwong (SRK), Lawal-Lake-Silberberg (LLS), Adachi-Lu-Sugie (ALS), Schmidt-Wenzel (SW), Patel-Teja (PT), Modified-Nasrifar-Moshfeghian (MNM), and Harmens-Knapp (HK). The results of comparison reveals that, with the exception of PR and ALS EOSs, all other EOSs yield consistently a higher average absolute percent deviation (AAPD) in the prediction of molar volume; it exceeds 20% by all mixtures. The grand average AAPD of all mixtures is 17 and 16 for PR and ALS, respectively. ALS is selected to represents the mixtures. It is modified by replacing the coefficient (Ωb1) of the parameter (b1) in the dominator of repulsive term by that of PR. This procedure enhanced the accuracy of ALS by 30 to 90% for individual mixtures and the grand average AAPD is significantly reduced from 16 to about 7.

Highlights

In the absence of the experimental PVT study, properties such as isothermal compressibility factor, z-factor, and formation volume factor, are determined from empirically derived correlations or equations of state (EOSs)
Adepoju [1] has made extensive study on Texas oil and found that Peng Robison (PR) [2], and Soave-RedlichKwong (SRK) [3] give a higher average absolute percent deviation (AAPD) in the prediction of the total volume of reservoir fluids. He obtained a good result when PR and SRK are modified by replacing the repulsion and attraction terms by that of Lawal-Lake-Silberberg (LLS) EOS
Akberzadeh et al [5] have investigated the ModifiedNasrifar-Moshfeghian (MNM) EOSs, PR, and SRK for Western Canadian heavy oils. They have shown that MNM without any volume correction predicted the densities with accuracy similar to SRK EOS with volume correction

Summary

Introduction

In the absence of the experimental PVT study, properties such as isothermal compressibility factor, z-factor, and formation volume factor, are determined from empirically derived correlations or equations of state (EOSs). Adepoju [1] has made extensive study on Texas oil and found that Peng Robison (PR) [2], and Soave-RedlichKwong (SRK) [3] give a higher average absolute percent deviation (AAPD) in the prediction of the total volume of reservoir fluids. He obtained a good result when PR and SRK are modified by replacing the repulsion and attraction terms by that of Lawal-Lake-Silberberg (LLS) EOS [4]. The candidate EOSs includes PR, SRK, LLS, ALS, SW, PT, MNM, and HK

PVT Study

Flash Algorithm

Results and Discussions

Conclusion