Effects of pore fluid chemistry on compaction of sand and sandstone reservoirs: From experiments to potential applications and associated risks

Abstract

To limit climate change and its impact on society and environment, anthropogenic emissions of greenhouse gases, such as CO2 and methane, must be reduced to zero or even to negative values by a portfolio of actions. These include both decarbonisation of the energy system, by switching to carbon-neutral energy sources such as wind, solar, geothermal and biomass, and elimination of emissions from fossil fuel use via carbon capture and storage (or utilisation). During the transition to a more sustainable energy system, natural gas, being a relatively low-carbon fossil fuel, is widely assumed to play an important interim-role. However, prolonged gas production is leading to surface subsidence and induced seismicity in an increasing number of gas fields around the world, due to depletion-driven compaction of the reservoir rock. The hesis addresses the geological and environmental risks related to subsurface fluid injection into depleted hydrocarbon reservoirs. It explores the effect of injected pore fluid chemistry on the mechanical behaviour of sands and sandstones, in the context of the potential for mitigating reservoir compaction caused by gas production, geothermal energy production and geological storage application.