Reply to Zoback and Gorelick: Geologic carbon storage remains a safe strategy to significantly reduce CO
            <sub>2</sub>
            emissions

Vilarrasa, Víctor; Carrera, Jesús

doi:10.1073/pnas.1511302112

Cited by 10 publications

(4 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, sedimentary rocks are critically stressed in some regions, like in the Valencia Through, which is an active seismic region. An accurate estimation of the stress state is essential to limit pore pressure buildup below a threshold to prevent induced seismicity (Vilarrasa & Carrera, 2015b; Zoback & Gorelick; 2015) (Figure 2b).…”

Section: Discussionmentioning

confidence: 99%

Unraveling the Causes of the Seismicity Induced by Underground Gas Storage at Castor, Spain

Vilarrasa

Simone

Carrera

et al. 2021

Geophysical Research Letters

Self Cite

View full text Add to dashboard Cite

The offshore Castor Underground Gas Storage (UGS) project had to be halted after gas injection triggered three M4 earthquakes, each larger than any ever induced by UGS. The mechanisms that induced seismicity in the crystalline basement at 5–10 km depth after gas injection at 1.7 km depth remain unknown. Here, we propose a combination of mechanisms to explain the observed seismicity. First, the critically stressed Amposta fault, bounding the storage formation, crept by the superposition of well‐known overpressure effects and buoyancy of the relatively light injected gas. This aseismic slip brought an unmapped critically stressed fault in the hydraulically disconnected crystalline basement to failure. We attribute the delay between induced earthquakes to the pressure drop associated to expansion of areas where earthquakes slips cause further instabilities. Earthquakes occur only after these pressure drops have dissipated. Understanding triggering mechanisms is key to forecast induced seismicity and successfully design deep underground operations.

show abstract

Section: Discussionmentioning

confidence: 99%

Unraveling the Causes of the Seismicity Induced by Underground Gas Storage at Castor, Spain

Vilarrasa

Simone

Carrera

et al. 2021

Geophysical Research Letters

Self Cite

View full text Add to dashboard Cite

show abstract

“…Recently, the feasibility of geologic carbon storage to significantly reduce CO 2 emissions has been put in doubt because it was compared with wastewater disposal [37], which is inducing a large number of large earthquakes (magnitude greater than 4) in the central US [38]. However, the geomechanical response of CO 2 injection will be completely different to that of wastewater disposal, making geological carbon storage a safe option for mitigating climate change [15,39].…”

Section: Caprock Geomechanical Stabilitymentioning

confidence: 99%

Two-phase flow effects on the CO₂injection pressure evolution and implications for the caprock geomechanical stability

2016

View full text Add to dashboard Cite

Abstract. Geologic carbon storage is considered to be one of the main solutions to significantly reduce CO2 emissions to the atmosphere to mitigate climate change. CO2 injection in deep geological formations entails a twophase flow, being CO2 the non-wetting phase. One of the main concerns of geologic carbon storage is whether the overpressure induced by CO2 injection may compromise the caprock integrity and faults stability. We numerically investigate the two-phase flow effects that govern the overpressure evolution generated by CO2 injection and how this overpressure affects the caprock geomechanical stability. We find that fluid pressure increases sharply at the beginning of injection because CO2 has to displace the brine that fills the pores around the injection well, which reduces the relative permeability. However, overpressure decreases subsequently because once CO2 fills the pores around the injection well, CO2 can flow easily due to its low viscosity and because the relative permeability to CO2 increases. Furthermore, the pressure drop that occurs in the capillary fringe due to two-phase flow interference decreases as the CO2 plume becomes larger. This overpressure evolution induced by CO2 injection, which remains practically constant with time after the initial peak, is very beneficial for maintaining caprock stability. Thus, the sealing capacity of the caprock will be maintained, preventing CO2 leakage to occur across the caprock.

show abstract

“…). Despite the potential of CO 2 injection to induce felt seismic events, there is an agreement that such large events can be avoided by performing a proper site characterization and pressure management (Vilarrasa & Carrera ; Zoback & Gorelick ).…”

Section: Introductionmentioning

confidence: 99%

“…Nevertheless, the magnitude of induced earthquakes in minor faults is unlikely to exceed magnitude 3, which may not cause damage to structures and infrastructures, but can still be felt by local population . Despite the potential of CO 2 injection to induce felt seismic events, there is an agreement that such large events can be avoided by performing a proper site characterization and pressure management (Vilarrasa & Carrera 2015b;Zoback & Gorelick 2015).…”

Section: Introductionmentioning

confidence: 99%

The role of the stress regime on microseismicity induced by overpressure and cooling in geologic carbon storage

Vilarrasa

2016

Geofluids

View full text Add to dashboard Cite

Fluid injection in deep geological formations usually induces microseismicity. In particular, industrial-scale injection of CO 2 may induce a large number of microseismic events. Since CO 2 is likely to reach the storage formation at a lower temperature than that corresponding to the geothermal gradient, both overpressure and cooling decrease the effective stresses and may induce microseismicity. Here, we investigate the effect of the stress regime on the effective stress evolution and fracture stability when injecting cold CO 2 through a horizontal well in a deep saline formation. Simulation results show that when only overpressure occurs, the vertical total stress remains practically constant, but the horizontal total stresses increase proportionally to overpressure. These hydro-mechanical stress changes result in a slight improvement in fracture stability in normal faulting stress regimes because the decrease in deviatoric stress offsets the decrease in effective stresses produced by overpressure. However, fracture stability significantly decreases in reverse faulting stress regimes because the size of the Mohr circle increases in addition to being displaced towards failure conditions. Fracture stability also decreases in strike slip stress regimes because the Mohr circle maintains its size and is shifted towards the yield surface a magnitude equal to overpressure minus the increase in the horizontal total stresses. Additionally, cooling induces a thermal stress reduction in all directions, but larger in the out-of-plane direction. This stress anisotropy causes, apart from a displacement of the Mohr circle towards the yield surface, an increase in the size of the Mohr circle. These two effects decrease fracture stability, resulting in the strike slip being the least stable stress regime when cooling occurs, followed by the reverse faulting and the normal faulting stress regimes. Thus, characterizing the stress state is crucial to determine the maximum sustainable injection pressure and maximum temperature drop to safely inject CO 2 .

show abstract

Reply to Zoback and Gorelick: Geologic carbon storage remains a safe strategy to significantly reduce CO ₂ emissions

Cited by 10 publications

References 6 publications

Unraveling the Causes of the Seismicity Induced by Underground Gas Storage at Castor, Spain

Unraveling the Causes of the Seismicity Induced by Underground Gas Storage at Castor, Spain

Two-phase flow effects on the CO₂injection pressure evolution and implications for the caprock geomechanical stability

The role of the stress regime on microseismicity induced by overpressure and cooling in geologic carbon storage

Contact Info

Product

Resources

About

Reply to Zoback and Gorelick: Geologic carbon storage remains a safe strategy to significantly reduce CO 2 emissions

Cited by 10 publications

References 6 publications

Unraveling the Causes of the Seismicity Induced by Underground Gas Storage at Castor, Spain

Unraveling the Causes of the Seismicity Induced by Underground Gas Storage at Castor, Spain

Two-phase flow effects on the CO2injection pressure evolution and implications for the caprock geomechanical stability

The role of the stress regime on microseismicity induced by overpressure and cooling in geologic carbon storage

Contact Info

Product

Resources

About

Reply to Zoback and Gorelick: Geologic carbon storage remains a safe strategy to significantly reduce CO ₂ emissions

Two-phase flow effects on the CO₂injection pressure evolution and implications for the caprock geomechanical stability