Fault Reactivation and CO2 Migration in Carbon Storage in a Saline Aquifer

Abstract. 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 wellbore stability and damage infrastructure. Thus, induced earthquakes should be minimized to successfully deploy geo-energies. However, numerous processes may trigger induced seismicity, which contribute to making it complex and translates into a limited forecast ability of current predictive models. We review the triggering mechanisms of induced seismicity. Specifically, we analyze (1) the impact of pore pressure evolution and the effect that properties of the injected fluid have on fracture and/or fault stability; (2) non-isothermal effects caused by the fact that the injected fluid usually reaches the injection formation at a lower temperature than that of the rock, inducing rock contraction, thermal stress reduction and stress redistribution around the cooled region; (3) local stress changes induced when low-permeability faults cross the injection formation, which may reduce their stability and eventually cause fault reactivation; (4) stress transfer caused by seismic or aseismic slip; and (5) geochemical effects, which may be especially relevant in carbonate-containing formations. We also review characterization techniques developed by the authors to reduce the uncertainty in rock properties and subsurface heterogeneity both for the screening of injection sites and for the operation of projects. Based on the review, we propose a methodology based on proper site characterization, monitoring and pressure management to minimize induced seismicity.

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Potential for Fault Reactivation Due to CO2 Injection in a Semi-Closed Saline Aquifer

Energy Procedia ◽

10.1016/j.egypro.2017.03.1460 ◽

2017 ◽

Vol 114 ◽

pp. 3282-3290 ◽

Cited By ~ 7

Author(s):

Victor Vilarrasa ◽

Roman Y. Makhnenko ◽

Lyesse Laloui

Keyword(s):

Fault Reactivation ◽

Co2 Injection ◽

Saline Aquifer

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Geologic carbon storage is unlikely to trigger large earthquakes and reactivate faults through which CO2 could leak

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1413284112 ◽

2015 ◽

Vol 112 (19) ◽

pp. 5938-5943 ◽

Cited By ~ 103

Author(s):

Victor Vilarrasa ◽

Jesus Carrera

Keyword(s):

Carbon Storage ◽

Induced Seismicity ◽

Clay Content ◽

Fault Reactivation ◽

Induced Earthquakes ◽

Localized Deformation ◽

Geologic Carbon Storage ◽

Entry Pressure ◽

Deep Underground ◽

Large Earthquakes

Zoback and Gorelick [(2012) Proc Natl Acad Sci USA 109(26):10164–10168] have claimed that geologic carbon storage in deep saline formations is very likely to trigger large induced seismicity, which may damage the caprock and ruin the objective of keeping CO2 stored deep underground. We argue that felt induced earthquakes due to geologic CO2 storage are unlikely because (i) sedimentary formations, which are softer than the crystalline basement, are rarely critically stressed; (ii) the least stable situation occurs at the beginning of injection, which makes it easy to control; (iii) CO2 dissolution into brine may help in reducing overpressure; and (iv) CO2 will not flow across the caprock because of capillarity, but brine will, which will reduce overpressure further. The latter two mechanisms ensure that overpressures caused by CO2 injection will dissipate in a moderate time after injection stops, hindering the occurrence of postinjection induced seismicity. Furthermore, even if microseismicity were induced, CO2 leakage through fault reactivation would be unlikely because the high clay content of caprocks ensures a reduced permeability and increased entry pressure along the localized deformation zone. For these reasons, we contend that properly sited and managed geologic carbon storage in deep saline formations remains a safe option to mitigate anthropogenic climate change.

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Impact of faults and compartmentalisation on geological carbon storage estimates in highly faulted basins

The APPEA Journal ◽

10.1071/aj16237 ◽

2017 ◽

Vol 57 (2) ◽

pp. 789

Author(s):

Jorik W. Poesse ◽

Ludovic P. Ricard ◽

Allison Hortle

Keyword(s):

Carbon Storage ◽

Storage Capacity ◽

Co2 Storage ◽

Fault Reactivation ◽

Hydrocarbon Exploration ◽

Co2 Injection ◽

Exploration And Production ◽

Order Of Magnitude ◽

Fault Permeability ◽

The Impact

Faults have extensively been studied for hydrocarbon exploration and production; however, previous studies on fault behaviour for geological carbon storage have focused on sealing capacity or reactivation potential during injection or post-injection phases. Little is known on the impact of faults for estimating storage capacity in highly faulted basins. A geological conceptual model of a representative compartment was designed to identify the key drivers of storage capacity estimates in highly faulted basins. An uncertainty quantification framework was then designed upon this model to address the impact of geological uncertainties such as fault permeability, reservoir injectivity, compartment geometry and closure on the compartment storage capacity. Pressure-limited storage capacity was estimated from numerical simulation of CO2 injection under the constraints of maximum bottom hole pressure and fault reactivation pressure. Interpretation of the simulation results highlights that (1) two injection regimes are observed: borehole- or fault-controlled, (2) storage capacity can vary more than an order of magnitude, (3) fault and reservoir permeability can be regarded as the most influential properties with respect to storage capacity, (4) compartment geometry mainly influences the injection regime controlling the storage capacity and (5) the large sensitivity of storage capacity to the type of enclosure and fault permeability indicates that pressure build-up at the fault is often the deciding factor for CO2 storage capacity.

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Implications of Early Cenozoic uplift and fault reactivation for carbon storage in the Moray Firth Basin

Interpretation ◽

10.1190/int-2017-0009.1 ◽

2017 ◽

Vol 5 (4) ◽

pp. SS1-SS21 ◽

Cited By ~ 7

Author(s):

Gustavo J. Guariguata-Rojas ◽

John R. Underhill

Keyword(s):

North Sea ◽

Fault Reactivation ◽

Normal Faults ◽

Storage Site ◽

Saline Aquifer ◽

The North ◽

Moray Firth ◽

New Interpretation ◽

A Site ◽

Early Cenozoic

Interpretation and depth conversion of an extensive, well-calibrated seismic database provide the basis upon which to map the limits and evaluate the geologic risks of using a saline aquifer target for carbon dioxide ([Formula: see text]) storage in the Moray Firth Basin of the North Sea. The seismic interpretation demonstrates that the Lower Cretaceous (Albian-Aptian) Captain Sandstone Member is a continuous, interconnected reservoir that rises to subcrop in the western areas of the basin as a consequence of Early Cenozoic uplift and tilt. As such, the aquifer forms an open system with few barriers or sizable closures to arrest or entrap light fluids and gases en route to its western subcrop. The new interpretation also indicates that the saline aquifer is cut by several west-southwest/east-northeast-striking reactivated normal faults. Although migration along the faults permitted hydrocarbons to get into structurally elevated traps, such as the Captain Field itself, some faults also breach the seal of the Captain Sandstone Member aquifer, rise to the seabed, and increase the risk of seabed leakage. Consequently, despite its large storage capacity, the dip, subcrop, and fault reactivation affecting the Captain Sandstone Member aquifer all suggest that its use as a site for [Formula: see text] storage remains unproven and is not the best choice for an initial North Sea exemplar. As such, the study highlights the importance of undertaking a robust and forensic geologic screening of any prospective storage site prior to injection.

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Induced seismicity in geologic carbon storage

10.5194/se-2018-129 ◽

2019 ◽

Author(s):

Víctor Vilarrasa ◽

Jesus Carrera ◽

Sebastià Olivella ◽

Jonny Rutqvist ◽

Lyesse Laloui

Keyword(s):

Carbon Storage ◽

Induced Seismicity ◽

Public Perception ◽

Fault Reactivation ◽

Wellbore Stability ◽

Rock Properties ◽

Induced Earthquakes ◽

Geologic Carbon Storage ◽

Stress Changes ◽

Injection Formation

Abstract. 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 wellbore stability and damage infrastructure. Thus, induced earthquakes should be minimized to successfully deploy geo-energies. However, the processes that trigger induced seismicity are not fully understood, which translates into a limited forecast ability of current predictive models. We aim at understanding the triggering mechanisms of induced seismicity and to develop methodologies to minimize its occurrence through dimensional and numerical analysis. We find that the properties of the injected fluid, e.g., water or CO2, have a significant effect on pressure buildup evolution and thus, on fracture/fault stability. In addition to pressure changes, the injected fluid usually reaches the injection formation at a lower temperature than that of the rock, inducing rock contraction, thermal stress reduction and stress redistribution around the cooled region. If low-permeable faults cross the injection formation, local stress changes are induced around them which may reduce their stability and eventually cause fault reactivation. To minimize the risk of inducing felt seismicity, we have developed characterization techniques to reduce the uncertainty on rock properties and subsurface heterogeneity both for the screening of injection sites and for the operation of projects. Overall, we contend that felt induced seismicity can be minimized provided that a proper site characterization, monitoring and pressure management are performed.

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