Mathematical Models for predicting CO2 Density and Viscosity for Enhanced Gas Recovery and Carbon Sequestration

Enyi, Godpower; Amadi, Ugwunna

Abstract

There is limited work on mathematical correlations in place for predicting density and viscosity of supercritical carbon-dioxide (CO2), necessary for Enhanced Gas Recovery-Carbon Sequestration (EGR-CS) operations. In this work, three categories of mathematical correlations were developed by Split Regression Analytical method and validated using Equation of State (EOS) models for predicting density and viscosity of carbon-dioxide under supercritical conditions as expected in EGR-CS operation. The models range for application is for reservoir depths of 1000-1500m, 1600-5000m and beyond 5000m for both CO2 density and viscosity, which are ideal for carbon sequestration and covers depths of most gas reservoirs in Niger-Delta. The new "UDA-Model" matched with Peng Robinson and Soave-Redlich-Kwong (EOS) models at the tested reservoir conditions, with low Absolute Average Deviation. Application of these mathematical correlations on four depleted gas reservoirs in Niger Delta formations shows Relative Density Difference (RDD) and Relative Viscosity Difference (RVD) on CO2 and natural gas. CO2 densities at those depths range from 0.5-0.6g/cm 3 , 0.6-0.7g/cm 3 , and 0.7-0.8g/cm 3 respectively while the viscosities range from 0.05-0.06cP, 0.06-0.07cP, and 0.07-0.08cP respectively. The results promise smoother displacement of natural gas by CO2 during EGR-CS operations.

• Journal Article Type: Review
• Acceptance Date: Dec 6, 2024
• Online Publication Date: Mar 18, 2025
• Publication Date: Mar 18, 2025
• Deposit Date: Mar 24, 2025
• Publicly Available Date: Mar 26, 2025
• Electronic ISSN: 2672-5401
• Peer Reviewed: Peer Reviewed
• Volume: 29
• Issue: 4
• Keywords: Mathematical correlations; CO2 density and viscosity; Enhanced Gas Recovery; Carbon Sequestration; Equation of State; Niger Delta formations