Optimizing Oil Recovery by Low-Pressure Nitrogen Injection: An Experiment Case Study
Abstract
Currently, most oilfields are in the final stages of development, making enhanced oil recovery (EOR) methods essential for efficient oil extraction. Among these methods, nitrogen injection has proven particularly effective. EOR encompasses advanced techniques aimed at maximizing oil extraction throughout an oilfield's productive lifespan. The process unfolds in stages: primary recovery (natural flow due to reservoir pressure), secondary recovery (water injection to maintain pressure), and tertiary recovery (methods like CO2, nitrogen injection, and steam recovery). This study investigates linear nitrogen injection at 0.7 MPa and 1 MPa over 24 hours to determine the most efficient method for the J-Sandstone Formation in the North Karamandybas field. Results indicate nitrogen injection effectively enhances oil recovery in lower to middle-permeability sandstone reservoirs at lower pressures. Using low salinity water injection, the oil recovery factor (RF) was approximately 50-55%. The linear displacement method proved particularly successful in gravity-stable injection scenarios, achieving an average RF of 65%, compared to 51% in gravity-unstable nitrogen flooding. Combined secondary and tertiary flooding with water and nitrogen achieved an average RF of 87.32%. These results underscore nitrogen injection's potential as a viable EOR technique for enhancing oil recovery in specific geological settings, particularly at lower pressures.