Cracking one of the deepest of problems
Associate Professor Ranjith PG is among leading researchers trying to assemble hard numbers and facts that will make geosequestration possible.
If you try to force too much water down a small plughole, it ends up going everywhere. ARC Future Fellow and Monash University Associate Professor Ranjith Gamage has found the same principle holds true when pumping liquid carbon dioxide into rock deep underground.
“After you inject for a certain period, say six months, then you have to stop for a period of time—a few months to a few years—because the carbon dioxide needs time to diffuse and equilibrate. Otherwise you risk cracking the rock due to the pressure buildup.”
What he’s talking about has significant implications for geosequestration—preventing carbon dioxide from escaping into the atmosphere by storing it underground. This strategy has become a key topic of consideration for governments around the world as they prepare to cope with climate change. And Ranjith has become one of the leading researchers trying to assemble hard numbers and facts on what geosequestration would involve.
The concept is simple: capture flue gas from a coal-fired power station or cement plant; liquefy it; transport it to a hole drilled one or two kilometres into the earth; and inject it into a coal seam or saline aquifer that can store it and hold it for thousands upon thousands of years.
If only it were so easy, says Ranjith, who is an expert in the movement of fluids through rock. First, you have to ensure that the gas stays put. The low density of carbon dioxide means that it will always rise, putting pressure on the rock above—the cap or sealing rock—which must have very low permeability and must not crack.
Then, there’s a question of economics. At a depth of one or two kilometres, each well costs between $20 and $50 million depending on the geological conditions. “You cannot drill an infinite number of holes. So how much can you inject down any one hole becomes an important question. And that’s where I’m focusing my work.”
Ranjith’s approach is a mix of experimental work and modelling. To assist, he has assembled the latest equipment into one of the most sophisticated testing facilities in the world. He needs to work at pressures which are several hundred times higher than those close to the surface, with rock samples 20 times larger than most existing pressure chambers can handle, and in temperatures of around of 50° Celsius.
He began by looking at unminable coal seams, which can absorb carbon dioxide while displacing methane. Now, with the help of the Future Fellowship he is broadening that work to study saline aquifers in sandstone. “The fellowship has allowed me to work full-time on my research, which has accelerated my progress.” It has also enhanced his ability to collaborate with colleagues in Germany, Japan, Canada, India, China and the European Union.
Ranjith has come a long way since his undergraduate degree in Sri Lanka and his PhD in rock mechanics at the University of Wollongong. He moved into geosequestration in 2004 after he recognised its importance, and that the areas in which he had working all his academic life provided the very skills need for the relevant research.
Pathegama Gamage, R., Khandelwal, M., 2012, Artificial neural network for prediction of air flow in a single rock joint, Neural Computing & Applications [P], vol 21, issue 6, Springer, New York USA, pp. 1413-1422.
Pathegama Gamage, R., Perera, M., 2011, A new triaxial apparatus to study the mechanical and fluid flow aspects of carbon dioxide sequestration in geological formations, Fuel [P], vol 90, issue 8, Elsevier Ltd, Oxford UK, pp. 2751-2759.
Chong, W., Haque, A., Pathegama Gamage, R., Shahinuzzaman, A., 2011, A parametric study of lateral load behaviour of single piles socketed into joint rock mass, Australian Geomechanics [P], vol 46, issue 1, Australian Geomechanics Society, Australia, pp. 43-50.
Perera, M., Pathegama Gamage, R., Choi, S., Bouazza, A., Kodikara, J., Airey, D., 2011, A review of coal properties pertinent to carbon dioxide sequestration in coal seams: with special reference to Victorian brown coals, Environmental Earth Sciences [P], vol 64, issue 1, Springer, New York USA, pp. 223-235.
Yasar, E., Pathegama Gamage, R., Viete, D., 2011, An experimental investigation into the drilling and physico-mechanical properties of a rock-like brittle material, Journal of Petroleum Science and Engineering [P], vol 76, issue 3-4, Elsevier Science BV, Amsterdam Netherlands, pp. 185-193.
Pathegama Gamage, R., Viete, D., 2011, Applicability of the 'cubic law' for non-Darcian fracture flow, Journal of Petroleum Science and Engineering [P], vol 78, issue 2, Elsevier Science BV, Amsterdam Netherlands, pp. 321-327.
Jasinge, D., Pathegama Gamage, R., Choi, S., 2011, Development of a reconstituted brown coal material using cement as a binder, Environmental Earth Sciences [P], vol 64, issue 3, Springer, New York USA, pp. 631-641.
Chong, W., Haque, A., Pathegama Gamage, R., Shahinuzzaman, A., 2011, Effect of joints on p-y behaviour of laterally loaded piles socketed into mudstone, International Journal of Rock Mechanics and Mining Sciences [P], vol 48, issue 3, Elsevier Ltd, Oxford UK, pp. 372-379.
Jasinge, D., Pathegama Gamage, R., Choi, S., 2011, Effects of effective stress changes on permeability of latrobe valley brown coal, Fuel [P], vol 90, issue 3, Elsevier Ltd, Oxford UK, pp. 1292-1300.
Chong, W., Haque, A., Pathegama Gamage, R., Shahinuzzaman, A., 2011, Effects of joints on p-y behaviour of laterally loaded piles socketed into mudstone, International Journal of Rock Mechanics and Mining Sciences [P], vol 48, issue 3, Pergamon-Elsevier Science, Oxford UK, pp. 372-379.
Perera, M., Pathegama Gamage, R., Mironov, P., 2011, Effects of saturation medium and pressure on strength parameters of Latrobe Valley brown coal: carbon dioxide, water and nitrogen saturations, Energy [P], vol 36, issue 12, Elsevier Ltd, Oxford UK, pp. 6941-6947.
Yellishetty, M., Mudd, G., Pathegama Gamage, R., Tharumarajah, A., 2011, Environmental life-cycle comparisons of steel production and recycling: sustainability issues, problems and prospects, Environmental Science and Policy [P], vol 14, Elsevier Inc, United States, pp. 650-663.
Perera, M., Pathegama Gamage, R., Choi, S., Airey, D., 2011, Numerical simulation of gas flow through porous sandstone and its experimental validation, Fuel [P], vol 90, issue 2, Elsevier Ltd, Oxford UK, pp. 547-554.
Shukla, R., Pathegama Gamage, R., Choi, S., Haque, A., 2011, Study of caprock integrity in geosequestration of carbon dioxide, International Journal of Geomechanics [P], vol 11, issue 4, American Society of Civil Engineers, USA, pp. 294-301.
Perera, M., Pathegama Gamage, R., Airey, D., Choi, S., 2011, Sub- and super-critical carbon dioxide flow behavior in naturally fractured black coal: an experimental study, Fuel [P], vol 90, issue 11, Elsevier Ltd, Oxford UK, pp. 3390-3397.
Darlington, W., Pathegama Gamage, R., Choi, S., 2011, The effect of specimen size on strength and other properties in laboratory testing of rock and rock-like cementitious brittle materials, Rock Mechanics and Rock Engineering [P], vol 44, issue 5, Springer Wien, Austria, pp. 513-529.
Perera, M., Pathegama Gamage, R., Choi, S., Airey, D., 2011, The effects of sub-critical and super-critical carbon dioxide adsorption-induced coal matrix swelling on the permeability of naturally fractured black coal, Energy [P], vol 36, issue 11, Elsevier Ltd, Oxford UK, pp. 6442-6450.
Firpo, G., Salvini, R., Francioni, M., Pathegama Gamage, R., 2011, Use of digital terrestrial photogrammetry in rocky slope stability analysis by distinct elements numerical methods, International Journal of Rock Mechanics and Mining Sciences [P], vol 48, issue 7, Elsevier Ltd, Oxford UK, pp. 1045-1054.
Academic prizes (national, international)
Australia-China Fellowship Award (given to only 8 researchers in Australia), 2011
Australian Academy of Science
Australian Future Fellowship Award, ARC, Australia, 2010
Australian Research Council
Australian Leadership Awards (ADC) 2012
ADC Forum
Dean Award for Excellence in Research- Faculty of Engineering at Monash University, 2010
Monash University
Research Accelerator Award, Monash University (for top 2% researcher), 2011
Monash University
Vice Chancellors’ Award for Excellence in Research - Early Career Researcher, 2011
Monash University
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