Nanoparticle-Stabilized Foam for Mobility Control in Enhanced Oil Recovery

摘要

Foam stabilized by a surfactant has been used successfully for mobility control during enhanced oil recovery processes, but the stability of the foam limits its application. Aqueous foams prepared from dispersions of partially hydrophobic silicon dioxide (SiO2) nanoparticles and sodium dodecyl sulfate (SDS) anionic surfactant were studied and the injection behavior of foams stabilized by a solution of SDS or dispersion of SiO2/SDS were analyzed for comparison. Foam stability increased with increasing nanoparticle concentration although the feasibility of producing a foam (foamability) followed the opposite trend. The surface tension and interfacial dilatational rheological properties were affected by the addition of SiO2 nanoparticles. When 0.05wt% SiO2 was added to the solution of SDS, the system's dilatational elasticity increased significantly, but not the dilatational viscosity. The sweep efficiency to dead end was very small, and the SiO2/SDS foam could displace more residual oil in the dead end than that in the SDS foam. The differential pressure could increase to 0.58MPa when SDS foam was injected, but for the SiO2/SDS foam it could increase to 1.7MPa. The SiO2/SDS foam exhibited better profile control performance than that of the SDS foam. When subsequent water was injected for 3.5 pore volumes, the flow rate of the high-permeability sand pack could still be maintained at 1.0mLmin(-1), which suggested that the SiO2/SDS foam had a better resistance to water flushing. Additionally, the foam volume should also be considered, especially for a SiO2 concentration of >1.5wt%. SiO2/SDS foam can reduce the residual oil saturation clearly, and the enhanced oil recovery and final oil recovery can reach 36.90 and 69.57%, respectively.