Victor Vilarrasa

Spanish National Research Council | CSIC · Mediterranean Institute for Advanced Studies (IMEDEA)

CO2 will remain in supercritical (SC) state (i.e. p>7.382 MPa and T>31.04 ºC) under the pressure (p) and temperature (T) conditions appropriate for geological storage. Thus, it is usually assumed that CO2 will reach the aquifer in SC conditions. However, inflowing CO2 does not need to be in thermal equilibrium with the aquifer. In fact, surface ope...

Significance Geologic carbon storage remains a safe option to mitigate anthropogenic climate change. Properly sited and managed storage sites are unlikely to induce felt seismicity because ( i ) sedimentary formations, which are softer than the crystalline basement, are rarely critically stressed; ( ii ) the least stable situation occurs at the beg...

Plain Language Summary Underground fluid injection for energy‐related activities usually induces microseismicity (not felt earthquakes). But felt earthquakes are sometimes induced, which may cause public concern and project cancellation. This was the case of the offshore Castor underground gas storage (UGS), Spain. Gas injection induced numerous se...

Supercritical geothermal systems are appealing sources of sustainable and carbon-free energy located in volcanic areas. Recent successes in drilling and exploration have opened new possibilities and spiked interest in this technology. Experimental and numerical studies have also confirmed the feasibility of creating fluid conducting fractures in se...

Geologic carbon storage, as well as other geo-energy applications, such as geothermal energy, seasonal natural gas storage and subsurface energy storage imply fluid injection and/or extraction that causes changes in rock stress field and may induce (micro)seismicity. If felt, seismicity has a negative effect on public perception and may jeopardize...

Geological carbon storage is one of the technologies required to arrive at the ambitious yet realistic net-zero emission target and climate change neutrality. Injected CO2 in geological formations acidifies the resident brine, inducing chemical reactions with the minerals. Reactions may alter the hydraulic and mechanical properties of the rock and...

Low-enthalpy geothermal energy (LEGE) is a carbon-free and renewable source to provide cooling and heating to infrastructures (e.g. buildings) by exchanging their temperature with that of the ground. The exchange of temperature modifies the groundwater temperature around LEGE installations, which may contribute to enhancing the capacity of aquifers...

Fluid injection into geological formations for energy resource development frequently induces (micro)seismicity. If intensely shaking the ground, induced earthquakes may cause injuries and/or economic loss, with the consequence of jeopardizing the operation and future development of these geoenergy projects. To achieve an improved understanding of...

Plain Language Summary Massive and timely deployment of Carbon Capture and Storage (CCS) at the gigatonne scale is a critical component of the majority of pathways toward reaching the Paris Agreement emissions abatement targets to mitigate climate change. Although CCS has been successfully deployed at multiple sites around the world, concerns about...

Urban aquifers are a valuable resource of freshwater for cities, however, their quality is degraded due to the presence of organic contaminants of emerging concern (CECs). The effects of organic CECs are largely unknown, but there is evidence that they pose a risk for human health, soil, plants and animals. Organic CECs are naturally degraded in aq...

Guaranteeing the sealing capacity of caprocks becomes paramount as CO2 storage scales up to the gigaton scale. A significant number of laboratory experiments have been performed with samples of intact rock, showing that low-permeability and high-entry pressure caprocks have excellent sealing capacities to contain CO2 deep underground. However, disc...

Induced seismicity is a limiting factor for the development of Enhanced Geothermal Systems (EGS) and has led to the cancellation of a few projects. Its causal mechanisms are not fully understood, especially those of post-injection seismicity. Here, we revisit the controversial case of the Basel EGS (Switzerland) to better understand the mechanisms...

Carbon capture and storage in deep geological formations is necessary to achieve a meaningful reduction of anthropogenic CO2 emissions into the atmosphere. Given the buoyancy of the injected CO2, it is essential to adequately characterize the sealing caprocks commonly comprised of clay-rich formations, including shales. If the inherent anisotropy o...

Deep geothermal energy (DGE) represents an opportunity for a sustainable and carbon-free energy supply. One of the main concerns of DGE is induced seismicity that may produce damaging earthquakes, challenging its widespread exploitation. It is widely believed that the seismicity risk can be controlled by using doublet systems circulating water to m...

Geologic carbon storage in deep saline aquifers has emerged as a promising technique to mitigate climate change. CO2 is buoyant at the storage conditions and tends to float over the resident brine jeopardizing long-term containment goals. Therefore, the caprock sealing capacity is of great importance and requires detailed assessment. We perform sup...

Many countries have assigned an indispensable role for carbon capture and storage (CCS) in their national climate change mitigation pathways. However, CCS deployment has stalled in most countries with only limited commercial projects realised mainly in hydrocarbon-rich countries for enhanced oil recovery. If the Paris Agreement is to be met, then t...

Geologic carbon storage is needed to meet the climate goal of limiting global warming to 1.5 ºC. Injecting in deep sedimentary formations brings CO2 to a supercritical state, yet less dense than the resident brine making it buoyant. Therefore, the assessment of the sealing capacity of the caprock lying above the storage reservoir is of paramount im...

It is widely accepted that massive deployment of Carbon Capture and Storage (CCS) in geologic media at the gigatonne scale should be part of the mitigating pathways toward net-zero CO2 emissions. For a successful geologic CO2 storage, the caprock sealing capacity and the associated governing processes have to be assessed in detail. In this contribu...

Carbon capture and geologic storage, mainly in deep saline aquifers, is extensively considered as an essential component of any strategy to achieve carbon neutrality and effectively mitigate climate change. At pressure and temperature conditions relevant to CO2 storage in sedimentary formations, CO2 is less dense than the resident brine and tends t...

Plain Language Summary The subsurface will play an important role in decarbonizing the economy. The transition to carbon neutrality can be accelerated by utilizing geothermal energy, returning carbon underground, and storing energy in the subsurface to offset the fluctuations in production of renewables. These low‐carbon geoenergy technologies ofte...

Displaced faults crossing the reservoir could significantly increase the induced earthquake frequency in geo‐energy projects. Understanding and predicting the stress variation in such cases is essential to minimize the risk of induced seismicity. Here, we adopt the inclusion theory to develop an analytical solution for the stress response to pore p...

Plain Language Summary Geologic carbon storage, which consists in returning carbon deep underground, should be part of the solution to effectively reach carbon neutrality by the middle of the century to mitigate climate change. CO2 has been traditionally proposed to be stored in sedimentary rock at depths below 800 m, where CO2 becomes a dense flui...

Geo-energy and geo-engineering applications, such as improved oil recovery (IOR), geologic carbon storage, and enhanced geothermal systems (EGSs), involve coupled thermo-hydro-mechanical (THM) processes that result from fluid injection and production. In some cases, reservoirs are highly fractured and the geomechanical response is controlled by fra...

The effect of natural CO2 leakage through water wells on groundwater chemistry from alluvial aquifers of Hamadan, Iran, has been investigated through analysis of water samples from 5 springs and 19 wells. The average CO2 partial pressure in gas charged groundwater has increased about 32 times with respect to background groundwater, leading to an in...

Geologic carbon storage, as well as other geo-energy applications, such as geothermal energy, seasonal natural gas storage and subsurface energy storage, imply fluid injection/extraction that causes changes in the effective stress field and induces (micro)seismicity. If felt, seismicity has a negative effect on public perception and may jeopardize...

We present a review of numerical studies aimed at understanding the conditions leading to the reactivation of a deep fracture zone, as well as thermal effects, at the In Salah CO2 Storage Project. Numerical simulations carried out with the TOUGH-FLAC coupled fluid flow and geomechanics simulator show that a deep fracture opening can explain the obs...

Geologic carbon storage is usually viewed as injecting, or rather as storing, CO2 in supercritical phase. This view is very demanding on the caprock, which must display: (1) high entry pressure to prevent an upward escape of CO2 due to density effects; (2) low permeability to minimize the upwards displacement of the brine induced by the injected CO...

Science of Carbon Storage in Deep Saline Formations: Process Coupling across Time and Spatial Scales summarizes state-of-the-art research, emphasizing how the coupling of physical and chemical processes as subsurface systems re-equilibrate during and after the injection of CO2. In addition, it addresses, in an easy-to-follow way, the lack of knowle...

In the framework of application of geological carbon storage (GCS), carbon dioxide (CO2) injection may lead to substantial cooling of the reservoir. Such cooling lasts for many years. In this chapter, up to date available data on thermal effects from various GCS sites are compared with theoretical results. Solutions for the latter are given for one...

The disposal of highly radioactive spent nuclear fuel in deep geological media will require excavating a large number of galleries in low-permeable rocks, altering initial rock integrity at the repository site. The FE tunnel excavated in Opalinus Clay at the Mont Terri Underground Research Laboratory (Switzerland) is a unique full-scale experiment...

Geologic carbon storage will most likely be feasible only if carbon dioxide (CO2) is utilized for improved oil recovery (IOR). The majority of carbonate reservoirs that bear hydrocarbons are fractured. Thus, the geomechanical response of the reservoir and caprock to IOR operations is controlled by pre-existing fractures. However, given the complexi...

Geologic carbon storage is considered as a requisite to effectively mitigate climate change, so large amounts of carbon dioxide (CO2) are expected to be injected in sedimentary saline formations. CO2 injection leads to the creation of acidic solution when it dissolves into the resident brine, which can react with reservoir rock, especially carbonat...

This contribution describes the thermo-hydro-mechanical (THM) simulation of gas injection as an enhanced oil recovery (EOR) method for improving oil production efficiency in fractured oil reservoirs. Gas migrates through predefined discontinuities with stress-dependent permeability. The aperture of these discrete fractures controls permeability and...

Injection-induced seismicity and caprock integrity are among the most important concerns in CO2 storage operations. Understanding and minimizing fault/fracture reactivation in the first place, and rupture growth/propagation beyond its surface afterwards, are fundamental to achieve a successful deployment of geologic carbon storage projects. Rock fr...

Induced microseismicity is a not-so-rare consequence of fluid injection into deep geological formations. Most seismicity occurs during injection, likely caused by overpressure. In some occasions, though, felt earthquakes of higher magnitude than those occurring during injection are triggered after stopping injection. The cause of post-injection sei...

Carbon dioxide (CO2) is likely to reach the bottom of injection wells at a colder temperature than that of the storage formation, causing cooling of the rock. This cooling, together with overpressure, tends to open up fractures, which may enhance injectivity. We investigate cooling effects on injectivity enhancement by modeling the In Salah CO2 sto...

CO2 leakage is a major concern for geologic carbon storage. To assess the caprock sealing capacity and the strength of faults, we test in the laboratory the rock types involved in CO2 storage at representative in-situ conditions. We use the measured parameters as input data to a numerical model that simulates CO2 injection in a deep saline aquifer...

Fluid injection operations, such as CO2 storage and enhanced oil recovery (EOR), imply reservoir pressurization, which changes the effective and total stresses due to poroelastic effects. These stress changes control the geomechanical stability of discontinuities like faults and fractures. Though the effect of these pre-existing discontinuities on...

Caprock formations are intended to prevent upwards carbon dioxide (CO2) migration to the surface during CO2 geological storage. Caprock interaction with CO2, as well as its potential consequences, requires to be predicted, and thus, need to be studied experimentally. Laboratory investigations of caprock behavior are complex due to its low permeabil...

We consider the feasibility of a novel Carbon Capture, Utilization and Storage (CCUS) concept that consists in producing oil and gas from hydrocarbon-rich shales overlying deep saline aquifers that are candidates for CO2 storage. Such geological overlapping between candidate aquifers for CO2 storage and shale plays exists in several sedimentary bas...

CO2 injection in extensive saline aquifers that present no faults is unlikely to damage the caprock sealing capacity. In contrast, CO2 injection in closed reservoirs will induce a large pressure buildup that may reactivate the low-permeable faults that bound the reservoir. However, the vast majority of CO2 storage formations will be extensive salin...

In geologic CO2 storage, it is important to find a proper barrier material that will avoid or limit acidic fluid migration. Shales that are ductile and have high capillary entry pressure and low permeability can be considered as good candidates for the caprock. Faults may contain high percentage of clay and act as barriers for fluid flow in reservo...

Overpressure caused by the direct injection of CO2 into a deep sedimentary system may produce changes in the state of stress, as well as, have an impact on the sealing capabilities of the targeted system. The importance of geomechanics including the potential for reactivating faults associated with large-scale geologic carbon sequestra- tion operat...

Fluid injection in the subsurface has significantly increased over the last decades. Since fluid injection causes pressure buildup, reducing effective stresses, shear failure conditions may eventually occur, inducing microseismic and seismic events. Anticipating felt induced earthquakes that may be triggered in undetected faults is crucial for the...

The governing equations and mathematical models describing CO2 spreading and trapping in saline aquifers and the related hydro-mechanical and chemical processes were described in Chapt. 3. In this chapter, the focus is on methods for solving the relevant equations. The chapter gives an overview of the different approaches, from high-fidelity full-p...

A necessary first step in qualifying a specific site for CO2 storage and for quantifying its relevant properties is a proper site characterization . Site characterization provides the ultimate input data for reservoir modeling and for all the predictions concerning the storage complex and its surroundings. It also provides baseline information for...

Current geomechanical applications imply nonisothermal processes of unsaturated geomaterials, in most cases following stress paths different from the classical triaxial compression often used in laboratory testing. Although the effects of temperature, suction, and stress-path direction (Lode’s angle) on the strength of geomaterials have been invest...

One of the most promising ways to significantly reduce greenhouse gases emissions, while carbon-free energy sources are developed, is Carbon Capture and Storage (CCS). Non-isothermal effects play a major role in all stages of CCS. In this paper, we review the literature on thermal effects related to CCS, which is receiving an increasing interest as...

Fluid injection in deep geological formations usually induces microseismicity. In particular, industrial-scale injection of CO2 may induce a large number of microseismic events. Since CO2 is likely to reach the storage formation at a lower temperature than that corresponding to the geothermal gradient, both overpressure and cooling decrease the eff...

Large amounts of carbon dioxide (CO2) should be injected in deep saline formations to mitigate climate change, implying geomechanical challenges that require further understanding. Pressure build-up induced by CO2 injection will decrease the effective stresses and may affect fault stability. Geomechanical effects of overpressure induced by CO2 inje...

In the light of current concerns related to induced seismicity associated with Geologic Carbon Sequestration (GCS), this paper summarizes lessons learned from recent modeling studies on fault activation, induced seismicity, and potential for leakage associated with deep underground CO2 injection. Model simulations demonstrate that seismic events la...

Pressure changes in the above zone, i.e., the overlying aquifer of an injection zone separated by a sealing caprock, are usually attributed to leakage through wells. However, pressure changes can be induced geomechanically due to rock deformation without any hydraulic connection between the injection zone and the above zone where the pressure chang...

Overpressure caused by the direct injection of CO2 into a deep sedimentary system may produce changes in the state of stress, as well as, have an impact on the sealing capabilities of the targeted system. The importance of geomechanics including the potential for reactivating faults associated with large-scale geologic carbon sequestration operatio...