MODEL FOR PREDICTING DENSITY AND VISCOSITY OF CO2 FOR ENHANCED GAS RECOVERY AND CARBON SEQUESTRATION IN DEPLETED GAS RESERVOIR. A CASE STUDY OF NIGER-DELTA FORMATION

Abstract

MODEL FOR PREDICTING DENSITY AND VISCOSITY OF CO2 FOR ENHANCED GAS RECOVERY AND CARBON SEQUESTRATION IN DEPLETED GAS RESERVOIR. A CASE STUDY OF NIGER-DELTA FORMATION In response to United Nations Paris Agreement of 2050 Carbon Neutrality Goal and in compliance with Kyoto Protocol on Clean Development Mechanism (CDM), all hands must be on deck to achieve these goals, including Niger-Delta region of Nigeria. No mathematical correlation in place for predicting density and viscosity of supercritical carbon-dioxide (CO2), necessary for Enhanced Gas Recovery - Carbon Sequestration (EGR-CS) operation in Niger-Delta Formation (NDF). Three categories of mathematical correlations were developed by Split Regression Analytical method (SRA) and validated using Equation of State Models (EOS-M) for predicting density and viscosity of pure carbon-dioxide under supercritical conditions as expected in (EGR-CS) operation. The models ranges from reservoir depths of 1000-1500m, 1600-5000m and beyond 5000m for both density and viscosity, which are ideal for carbon sequestration and covers depths of most gas reservoirs in Niger-Delta. The new “NDF-Model” matched with Peng Robinson and Soave-Redlich-Kwong Equation of States (EOS) at the tested reservoir conditions, with low Absolute Average Deviation (AAD). Application of these models on four depleted gas reservoirs (Res.1, Res.2, Res.3 & Res.4) in Niger-Delta Formation (NDF) shows encouraging Relative Density Difference (RDD) and Relative Viscosity Difference (RVD). CO2 densities at those depths ranges from 0.5 - 0.6 g/cm3 , 0.6 - 0.7g/cm3 and 0.7 -0.8g/cm3 respectively while the viscosities ranges from 0.05 - 0.06cP, 0.06 - 0.07cP and 0.07 - 0.08cP respectively, which promises smoother displacement of natural gas by CO2 during Enhanced Gas Recovery.