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PETROMAKS2-Stort program petroleum

Clean offshore energy by hydrogen storage in petroleum reservoirs

Alternative title: Ren offshore energi ved hydrogenlagring i olje- og gassreservoarer

Awarded: NOK 12.4 mill.

Emissions from petroleum production stand for over 25% of Norway's total CO2 emissions, and these must be significantly reduced for the country to reach its ambitions in the Paris Agreement. One way to reduce these emissions is to go over to renwable energies to power all the operations and the offshore platforms themselves. However, due to the intermittent nature of renewable energy production such as wind and solar sources, it is necessary to be able to store surplus energy to make it available when production levels drop (e.g. at night or when the wind stops blowing). In the present project we investigate whether energy, in the form of hydrogen (H2), can be stored safely underground in abandoned oil and gas reservoirs. These are widely available in Norway, and their use for H2 storage can open for a renewable offshore future for the country by powering petroleum platforms. The project involves a national team of world-renowned experts in the fields of geochemistry (chemistry applied to mineral reactions in rocks), geomechanics (solid mechanics applied to porous rocks), materials science and reservoir flow modelling (study of the pore fluid flow in underground rocks) from SINTEF, NORCE and the University of Oslo, and an international research partner from Queen Mary University of London, an acclaimed expert in oilfield chemistry and flow in porous media (such as oil-bearing rocks). Through experiments and modelling, the team will study the fundamental interaction of H2 with rocks in the subsurface, reservoir flow and caprock integrity. Caprocks are sealing rock formations above reservoirs, keeping fluids such as oil or gas confined in the pores of the reservoir rock. The first work in the project has been to create a clickable map of the North Sea, with estimates of the hydrogen storage capacity in the Norwegian sector. Special attention is given to areas where wind parks are planned, and to areas with large oil and gas aktivities, which come with accessible large fields that could be used to store hydrogen. The user can obtain information about the potential for H2 storage, in volume and corresponding energy potential. The results indicate that the large fields have the capacity to store Norway's annual energy needs. Modelling also shows that the risk of significant loss of H2 through cap rock is small, with diffusion only exceeding 10 m after 10,000 years (and that if the resrvoir is kept full at all times, while in practice the storage is emptied and refilled all the time). A student from Ecole Polytechnique in Paris visited SINTEF in the spring and looked at fatigue effects on cap rock that seals a reservoir, where it is filled and emptied of H2 cyclically. The results show that it is important not to completely empty the reservoir every cycle, otherwise areas around the reservoir are deforming more and more, with the risk of the rock fracturing and a potential leakage path appearing. In the laboratory, both sandstone and shale cores were exposed to H2 for long duration, to be tested for changes in mechanical properties. Fortunately, major differences were not measured against control tests without exposure, which reinforces the belief that the storage concept is viable, even though the analysis of the pore fluid in the cores points to some chemical changes. These results have been presented in 3 different conferences and received good feedback and interest. Another student from Ecole Polytechnique has further developed a clickable map solution (GIS) that shows the capacity of the large old gas reservoirs offshore Norway to store H2, and what it corresponds to in kWh. She used different methods to calculate the available pore volume and how much H2 can fill these pores. Post-doc M. Masoudi has been on a short stay at Herriot Watt University in Scotland, to exchange knowledge about geochemical modeling in porous media.Recently, two days were also spent at the core repository of the Norwegian Petroleum Directorate (NPD) to drill core samples from many old fields on the Norwegian continental shelf, from many different rock formations. The samples have been transported back to SINTEF and will be characterized and exposed to H2 by two new masters students from Bremen in Germany, who have just arrived in Trondheim.

Emissions from petroleum production stand for over 25% of Norway's total CO2 emissions, and these must be significantly reduced for the country to reach its ambitions in the Paris Agreement. Powering offshore platforms by renewables is thus an important goal, but it relies on large-scale energy storage options for balancing out the mismatch between power supply and demand. In the present project we investigate whether energy, in the form of hydrogen (H2), can be stored safely underground in depleted oil and gas reservoirs. These are widely available in Norway, and their use for H2 storage can open for a renewable offshore future for the country by powering petroleum platforms. The project involves a national team of world-renowned experts in the fields of geochemistry, geomechanics, materials science and reservoir flow modelling from SINTEF, NORCE and the University of Oslo, and an international research partner from Queen Mary University of London, an acclaimed expert in oilfield chemistry and flow in porous media. Through experiments and modelling, the team will study the fundamental geochemical effects of H2 in the subsurface, reservoir flow and caprock integrity. This will give a first indication on whether future, more applied, research projects should be initiated on the topic.

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PETROMAKS2-Stort program petroleum