APPLICATION OF FOAM FLOODING FOR RESIDUAL OIL PRODUCTION IN THE “X” OILFIELD

Abstract

Foam is a known diverting agent capable of improving sweep efficiency. It is speculated that foam flooding can also improve microscopic displacement efficiency in the reservoir core by the same mechanism. Recovery of trapped residual hydrocarbon fluid in the oilfield “X” core is investigated in this thesis. To quantify the recovery of bypassed resources on the core level, the application of foam flooding was investigated in the reservoir core and contrasted with the same recovery process sequence on homogeneous sandstone and carbonate quarried outcrop core. The study was the first to identify promising foam formulations using atmospheric bulk foam stability tests and use such foaming formulations with and without nanoparticle addition in immiscible core flood tests with nitrogen (N2) and carbon dioxide (CO2) carrier fluids. Screening experiments of bulk foam stability were conducted as a precursor to core flooding studies. Foam half-life tests substantiated a negative influence of increasing salinity (NaCl) on foam stability. Appropriate baseline production from sequential water flooding and gas flooding preceded foam flooding assessments with both nitrogen and carbon dioxide gas options. Such tests were conducted in both reservoir and outcrop cores. Oil recovery and resistance factor observations were compared between reservoir and outcrop core, N2 and CO2 gas, and foam formulations with and without nanoparticle addition. The X oilfield experiments confirmed significant EOR potential with foam processes, especially by adding nanoparticles. Baseline studies on gas flooding prior to foam introduction showed that CO2 gas flooding is more efficient than N2 flooding, even at low pressure, presumably due to the presence of additional interaction mechanisms with CO2. Whether nanoparticles were present or not, the data showed that N2 foam was more efficient than CO2 foam, as evidenced by higher Recovery-8.15 % of Original Oil in Place (OOIP) with N2 foam in “X” core samples compared to 2.45 % with CO2 foam. Moreover, recovery was improved with the addition of NP to the foam formulation, resulting in an average additional recovery factor of 5.05%. However, the higher apparent viscosity of N₂ foam with nanoparticles (about 9 cP) must be carefully considered before field usage due to the associated mobility reduction, despite the dramatic increase in the recovery efficiency. In general, from the findings of this study, it appears that foam flooding is a feasible approach for enhancing sweep in the "X" oilfield.