Gelled Emulsions of CO2-Water-Nanoparticles
- 30 September 2013
- conference paper
- conference paper
- Published by Society of Petroleum Engineers (SPE) in Day 2 Tue, October 01, 2013
Abstract
Enhanced oil recovery by CO2 injection is an effective method for recovering additional oil beyond waterflooding. In recent years it has garnered a lot of attention for two primary reasons: (a) the stable high price of oil and (b) environmental aspects of CO2 sequestration. Its use has been increasing steadily over the past few years. In many respects it is a win-win situation with CO2 sequestration and additional, incremental oil produced. However, the CO2-EOR process is handicapped, especially in thick reservoirs, by CO2 gravity override. Due to density differences between the injected CO2 and resident fluids in the reservoir, the lighter CO2 tends to rise to the top of the reservoir thereby bypassing some of the remaining oil. This results in poor sweep efficiency and conformance. Different techniques have been used to overcome the CO2 gravity override by either increasing its density, viscosity, or reducing its relative permeability. This paper investigates the use of gelling CO2-water emulsions, stabilized by silica nano-particles, to control the mobility of CO2. The stability of nano-particles was first investigated using iso-octane (iC8) as a proxy for CO2. The stability of these emulsions, or foams, was investigated as a function of nano-particles concentration, type, hydrophilicity degree, and also as a function of iC8/water ratio. The silica nano-particles concentration ranged from 0.5 to 2 wt%, and iC8 phase volume ranged between 50 and 90%. Stability experiments were conducted at room temperature and up to 17 hours using both hydrophobic and hydrophilic colloidal silica nano-particles. Following the screening studies with iC8, rheological measurements were made using CO2 at 200°F and 1,800 psi at different (CO2/water) ratios and nano-particles concentrations. Compared to pure liquid CO2, high emulsion viscosities from 1.1 to nearly 2.5 cP were achieved. These values represent almost a 100-fold increase over pure sc-CO2 viscosity. Additionally, in some cases rigid gels were observed with time following emulsion generation. The CO2-water-nanoparticle emulsions were generally stable. This work provides the rheological results of the emulsion systems as a function of time, nano-particles concentration and CO2 phase volume. The high viscosity CO2/water emulsions have the capability to enhance CO2 mobility, act as a diverting agent during CO2-EOR, and improve sweep efficiency.Keywords
This publication has 21 references indexed in Scilit:
- Enhanced Oil Recovery: An Update ReviewEnergies, 2010
- Solubilization of TX-100™ and PEG-PPG-PEG in Liquid Carbon DioxideSeparation Science and Technology, 2010
- Design and Evaluation of Nonfluorous CO2-Soluble Oligomers and PolymersThe Journal of Physical Chemistry B, 2009
- Water-in-carbon dioxide emulsions stabilized with hydrophobic silica particlesPhysical Chemistry Chemical Physics, 2007
- Macroemulsions of Liquid and Supercritical CO2-in-Water and Water-in-Liquid CO2 Stabilized by Fine ParticlesIndustrial & Engineering Chemistry Research, 2006
- Functional Oligo(vinyl acetate) CO2-philes for Solubilization and EmulsificationJournal of the American Chemical Society, 2005
- Stabilization of Carbon Dioxide-in-Water Emulsions with Silica NanoparticlesLangmuir, 2004
- Phase behavior of CO2–perfluoropolyether oil mixtures and CO2–perfluoropolyether chelating agent mixturesThe Journal of Supercritical Fluids, 1998
- A Thermodynamic Correlation for the Minimum Miscibility Pressure in CO2 Flooding of Petroleum ReservoirsSPE Reservoir Engineering, 1988
- Flow Visualization for CO2/Crude-Oil DisplacementsSociety of Petroleum Engineers Journal, 1985