High-Temperature Stability of Aqueous Foams for Potential Waterless Hydrofracking Application in Enhanced Geothermal System (EGS)
Abstract
Enhanced Geothermal System (EGS) utilizes artificial reservoirs created by injecting high-pressure cold water into the hot dry rocks (HDR) under carefully controlled conditions. This process, known as hydrofracking, typically involves the use of a large quantity of water. Recent research has been carried out to develop waterless fracturing technologies for EGS, including foam-based hydrofracking. Foam fracturing fluids have potential benefits over water-based fluids in consideration of water consumption, formation damage, and environmental impacts. Although foam fracturing has proven to be effective in some oil and gas applications, it has not been demonstrated on EGS. One potential challenge of utilizing foam fracturing for EGS applications is the uncertainty in foam stability, which is known to degrade as temperature increases.
This research is focused on studying the thermal stability of foam-based fracturing fluid at high temperature. A laboratory apparatus has been constructed for measuring foam stability between room temperature and 200°C, which is the average temperature of HDRs. Foam stability at high temperature was measure based on foam half-life at a pressure of 10 psi. Two types of gases, N2 and CO2, and two types of surfactants, Alfa olefin sulfonate (AOS) and sodium dodecyl sulfate (SDS), with concentrations ranging between 0.1 and 1 wt. % were studied. Effects of a gelling agent guar (0.25 to 0.36 wt. %) and silica nanoparticles (size 60 nm to 150 nm, 0.01 to 0.5 wt. %) on the foam stability were also tested. The preliminary results showed that SDS foams were more stable at room temperature but less stable at high temperatures than the AOS foams. Guar increased the half-life of foams at high temperatures by increasing viscosity of the foam. SiO2 nanoparticles also increased the half-life of foams at higher temperatures, which might be related to the blocking effect of the nanoparticles at the lamella borders that could reduce drainage in the foams.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.H51L1647T
- Keywords:
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- 1822 Geomechanics;
- HYDROLOGY;
- 1847 Modeling;
- HYDROLOGY;
- 1869 Stochastic hydrology;
- HYDROLOGY;
- 1873 Uncertainty assessment;
- HYDROLOGY