Static And Dynamic Characteristics Of Nanosilica Particles Stabilized Co2 Foam For Mobility Control Application

Static and Dynamic Characteristics of Nanosilica Particles Stabilized CO2 Foam for Mobility Control Application

Nanoparticle-stabilized CO2 Foams for Potential Mobility Control Applications

Carbon dioxide (CO2) flooding is the second most common tertiary recovery technique implemented in the United States. Yet, there is huge potential to advance the process by improving the volumetric sweep efficiency of injected CO2. Delivering CO2 into the reservoir as a foam is one way to do this. Surfactants have traditionally been used to generate CO2 foams for mobility control; however, the use of nanoparticles as a foam stabilizing agent provides several advantages. Surfactant-stabilized foams require constant regeneration to be effective, and the surfactant is adsorbed onto reservoir rocks and is prone to chemical degradation at harsh reservoir conditions. Nanoparticle-stabilized foams have been found to be tolerant of high temperature and high salinity environments. Their nano size also allows them to be transported through reservoir rocks without blocking pore throats. Stable CO2-in-water foams were generated using 5 nm silica nanoparticles with a short chain polyethylene glycol surface coating. These foams were generated by the co-injection of CO2 and a nanoparticle dispersion through both rock matrix and fractures. A threshold shear rate was found to exist for foam generation in both fractured and non-fractured Boise sandstone cores. The ability of nanoparticles to generate foams only above a threshold shear rate is advantageous; in field applications, high shear rates are associated with high permeability zones, where the presence of foam is desired. Reducing CO2 mobility in these high permeability zones diverts CO2 into lower permeability regions containing not yet swept oil. Nanoparticles were also found to be able to stabilize CO2 foams by co-injection through rough-walled fractures in cement cores, demonstrating their ability to stabilize foams without matrix flow. Experiments were conducted on the ability of fly ash, a waste product from burning coal in power plants, to stabilize oil-in-water emulsions and CO2 foams. The use of fly ash particles as a foam stabilizing agent would significantly reduce material costs for potential tertiary oil recovery and CO2 sequestration applications. Nano-milled fly ash particles without surface treatment were able to generate stable oil-in-water emulsions when high frequency, high energy vibrations were applied to a mixture of fly ash dispersion and dodecane. Oil-in-water emulsions were also generated by co-injecting fly ash and dodecane, a low pressure analog to CO2, through a beadpack. Emulsions generated by co-injection, however, were unstable and coalesced within an hour. A threshold shear rate was required for the emulsion generation. Fly ash particles were found to be able to stabilize CO2 foam in a high pressure batch mixing cell, but not by co-injection through a beadpack. Dispersions of fly ash particles were found to be stable only at low salinities (

Experimental Study of Nanosilica-stabilized CO2 Foam for Mobility Control and Oil Recovery