Modeling of Pressure Dependence of Interfacial Tension Behaviors of a Complex Supercritical CO2 + Live Crude Oil System Using a Basic Parachor Expression

Dayanand Saini

doi:10.4172/2157-7463.1000277

Abstract

Parachor based basic expressions are often used to model the experimentally observed pressure dependence of interfacial tension (IFT) behaviors of complex supercritical CO2 + crude oil (dead or live) mixtures at elevated temperatures. However, such modeling requires compositions and densities of the equilibrium liquid and vapor phases and molecular weights of various components present in the system. In the absence of measured data, often phase behavior packages are used for obtaining these input data for performing calculations. Very few researchers have used experimentally measured input data for performing parachor based modeling of the experimental IFT behaviors of complex supercritical CO2 + live crude oil systems. This study presents the results of a basic parachor model based modeling of pressure dependence of IFT behaviors of a complex supercritical CO2 + live crude oil system for which experimentally measured input data is available in public domain. Though the calculated IFT behaviors showed significant deviation from the experimentally measured behaviors at a given pressure, calculated IFT versus pressure trends appeared to follow the experimental observed trends closely. Also, despite a large variation in the compositions of feed supercritical CO2 + live crude oil mixtures, both trends (calculated and experimental) converged rapidly to attain a near zero IFT condition at more or less same pressure.

Highlights

In the CO2 injection based enhanced oil recovery (EOR) operations; injected supercritical CO2 interacts with reservoir crude oil in a multiple-contact fashion to develop a low interfacial tension (IFT) condition between the two phases that plays a crucial role in achieving low residual oil saturation
Absolute variation between the individual IFT value measured at the highest experimental pressure (41.3 MPa) and corresponding calculated IFT value ranged from 50% to 187% (Table 1), both the calculated and the experimental IFT behaviors (IFT versus 1/Pressure), converged to more or less a same pressure value when extrapolated to zero IFT condition
In cases of other three feed mixtures, the equilibrium oil and vapor phases showed a density difference in the range from 0.0788 gm/cm3 (53 - 74 mol.% CO2) to 0.1722 gm/cm3 (89 - 95 mol.% CO2). It did not change the end result i.e. convergence of both the calculated and the experimental IFT behaviors to more or less a same pressure value when extrapolated to zero IFT condition

Summary

Introduction

In the CO2 injection based enhanced oil recovery (EOR) operations; injected supercritical CO2 interacts with reservoir crude oil in a multiple-contact fashion to develop a low IFT condition between the two phases that plays a crucial role in achieving low residual oil saturation. Present study is only limited to perform basic parachor expression based modeling for predicting pressure dependence of IFT behaviors of complex supercritical CO2 + live crude oil systems.

Results

Conclusion