Unexpected fault activation due to underground gas storage in produced reservoirs. Part II: Definition of safe operational bandwidths

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Main Authors: Baldan, Selena, Ferronato, Massimiliano, Franceschini, Andrea, Janna, Carlo, Zoccarato, Claudia, Frigo, Matteo, Isotton, Giovanni, Collettini, Cristiano, Deangeli, Chiara, Rocca, Vera, Verga, Francesca, Teatini, Pietro
Format: Preprint
Published: 2024
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author Baldan, Selena
Ferronato, Massimiliano
Franceschini, Andrea
Janna, Carlo
Zoccarato, Claudia
Frigo, Matteo
Isotton, Giovanni
Collettini, Cristiano
Deangeli, Chiara
Rocca, Vera
Verga, Francesca
Teatini, Pietro
author_facet Baldan, Selena
Ferronato, Massimiliano
Franceschini, Andrea
Janna, Carlo
Zoccarato, Claudia
Frigo, Matteo
Isotton, Giovanni
Collettini, Cristiano
Deangeli, Chiara
Rocca, Vera
Verga, Francesca
Teatini, Pietro
contents Underground gas storage is a versatile tool for managing energy resources and addressing pressing environmental concerns. While natural gas is stored in geological formations since the early 20th century, hydrogen has recently been considered as a potential candidate toward a more flexible and sustainable energy infrastructure. Furthermore, these formations can additionally capture gases that contribute to climate change, such as CO2. When such operations are implemented in faulted basins, however, safety concerns may arise due to the potential reactivation of pre-existing faults, which could trigger (micro)-seismicity events. In the Netherlands, it has been recently noted that fault reactivation can occur "unexpectedly" during the life of an underground gas storage (UGS) site, even when stress conditions are not expected to cause a failure. The present two-part work aims to develop a modeling framework to investigate the physical mechanisms causing such occurrences in previously produced gas reservoirs and define a safe operational bandwidth for pore pressure variation for UGS operations in the faulted reservoirs of the Upper Rotliegend Group, the Netherlands. This paper investigates in detail the mechanisms and crucial factors that result in fault reactivation at various stages of a UGS. The mathematical and numerical model described in Part I is used, also considering how the presence of stored gases may influence the mechanical properties of the reservoir and caprock, in particular the Young modulus. The study investigates the hazard of fault activation caused by the storage of different fluids for various purposes, such as long-term CO2 sequestration, CH4 and H2 injection and extraction cycles, and N2 injection as cushion gas. The results show how geological configuration, geomechanical properties, and reservoir operating conditions may increase the hazard of fault reactivation.
format Preprint
id arxiv_https___arxiv_org_abs_2408_01049
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Unexpected fault activation due to underground gas storage in produced reservoirs. Part II: Definition of safe operational bandwidths
Baldan, Selena
Ferronato, Massimiliano
Franceschini, Andrea
Janna, Carlo
Zoccarato, Claudia
Frigo, Matteo
Isotton, Giovanni
Collettini, Cristiano
Deangeli, Chiara
Rocca, Vera
Verga, Francesca
Teatini, Pietro
Numerical Analysis
Underground gas storage is a versatile tool for managing energy resources and addressing pressing environmental concerns. While natural gas is stored in geological formations since the early 20th century, hydrogen has recently been considered as a potential candidate toward a more flexible and sustainable energy infrastructure. Furthermore, these formations can additionally capture gases that contribute to climate change, such as CO2. When such operations are implemented in faulted basins, however, safety concerns may arise due to the potential reactivation of pre-existing faults, which could trigger (micro)-seismicity events. In the Netherlands, it has been recently noted that fault reactivation can occur "unexpectedly" during the life of an underground gas storage (UGS) site, even when stress conditions are not expected to cause a failure. The present two-part work aims to develop a modeling framework to investigate the physical mechanisms causing such occurrences in previously produced gas reservoirs and define a safe operational bandwidth for pore pressure variation for UGS operations in the faulted reservoirs of the Upper Rotliegend Group, the Netherlands. This paper investigates in detail the mechanisms and crucial factors that result in fault reactivation at various stages of a UGS. The mathematical and numerical model described in Part I is used, also considering how the presence of stored gases may influence the mechanical properties of the reservoir and caprock, in particular the Young modulus. The study investigates the hazard of fault activation caused by the storage of different fluids for various purposes, such as long-term CO2 sequestration, CH4 and H2 injection and extraction cycles, and N2 injection as cushion gas. The results show how geological configuration, geomechanical properties, and reservoir operating conditions may increase the hazard of fault reactivation.
title Unexpected fault activation due to underground gas storage in produced reservoirs. Part II: Definition of safe operational bandwidths
topic Numerical Analysis
url https://arxiv.org/abs/2408.01049