Transport properties of siliciclastic saline reservoirs with non-connected fractures during CO2 geosequestration
Abstract
To guarantee safe and long-term CO2 storage in fractured reservoirs, the effect of reservoir fractures on the multiphase flow has to be assessed. Interconnected fracture networks may lead to fast CO2 flow through the reservoir, but the role of isolated fractures remains unclear. Here, we study the transport properties of non-connected fractured saline siliciclastic CO2 storage reservoirs. We performed a brine-CO2 flow-through (BCFT) using synthetic sandstone with well-distributed non-connected fractures aligned 45 degrees to the fracture normal. The brine:CO2 fractional flow was increased from 100:0 to 0:100 by steps of 20% (i.e., drainage). After the maximum CO2 saturation ( 60%) was achieved, the sample was flushed back with the original brine to complete the test (i.e., forced imbibition). During the BCFT, 63 PVs (pore volume, PV, 10 mL) were flushed through the sample. We monitored pore pressure up- and down-stream of the sample, temperature, and axial and radial strains in continuous, while bulk electrical resistivity was measured twice every PV. The fractured sample showed low relative permeability curves cross point and end-point relative permeability to CO2 values when compared to results from similar experiments performed with three non-fractured samples (Papageorgiou et al. 2018), indicating that the presence of fractures affects the wettability and mobility of the individual phases. Our results suggest that the non-connected fracture network partially isolates the non-wetting phase, favouring the trapping of CO2 in the porous medium and improving the overall CO2 storage efficiency of the reservoir. This finding challenges the assumption that fractured reservoirs are unsuitable geological formations for CO2 storage.
Papageorgiou, G., Falcon-Suarez, I., Chapman, M. & Best, A., 2018. Pressure-varying CO2 distribution affects the ultrasonic velocities of synthetic sandstones, International Journal of Greenhouse Gas Control, 74, 1-8.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMMR34A..02M
- Keywords:
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- 0545 Modeling;
- COMPUTATIONAL GEOPHYSICSDE: 1822 Geomechanics;
- HYDROLOGYDE: 5102 Acoustic properties;
- PHYSICAL PROPERTIES OF ROCKSDE: 5139 Transport properties;
- PHYSICAL PROPERTIES OF ROCKS