Potential of nitrogen gas miscible injection in South East assets, Abu Dhabi

This study evaluated the potential for application of miscible nitrogen injection to South East assets in Abu Dhabi which include three giant onshore oil fields. MMP (Minimum miscibility pressure) for different N2- oil systems was determined as a key criterion for screening. CMG simulation and correlations approaches were employed for determining pure N2 MMP. Results of the study demonstrated that pure nitrogen miscible injection is promising for some reservoirs in the SE fields when reservoir pressure is higher than the MMP. Different correlations have been investigated for suitability to Abu Dhabi crude oils. Investigated MMP correlations are applied to the available data sets and a comprehensive error analysis is performed based on a comparison of the predicted value using published correlations with the simulated value using CMG simulator. Two simulation methods were employed to calculate MMP's: cell to cell and key tie line. The Hudgins and Sebastian correlations are in a good agreement with the simulated MMP indicated by small absolute deviation of 10.9% and 2.9% respectively. Glaso, Hanssen, and Firoozabadi correlations produced unrealistic results. The impact of critical parameters such as Cl fraction, C2-C5 fraction, and molecular weight of C7+, API, and temperature on the MMP of nitrogen injection was investigated.