Pore Pressure Analysis for Distinguishing Earthquakes Induced by CO2 Injection from Natural Earthquakes

Abstract

It is important to distinguish between natural earthquakes and those induced by CO2 injection at carbon capture and storage sites. For example, the 2004 Mw 6.8 Chuetsu earthquake occurred close to the Nagaoka CO2 storage site during gas injection, but we could not quantify whether the earthquake was due to CO2 injection or not. Here, changes in pore pressure during CO2 injection at the Nagaoka site were simulated and compared with estimated natural seasonal fluctuations in pore pressure due to rainfall and snowmelt, as well as estimated pore pressure increases related to remote earthquakes. Changes in pore pressure due to CO2 injection were clearly distinguished from those due to rainfall and snowmelt. The simulated local increase in pore pressure at the seismogenic fault area was much less than the seasonal fluctuations related to precipitation and increases caused by remote earthquakes, and the lateral extent of pore pressure increase was insufficient to influence seismogenic faults. We also demonstrated that pore pressure changes due to distant earthquakes are capable of triggering slip on seismogenic faults. The approach we developed could be used to distinguish natural from injection-induced earthquakes and will be useful for that purpose at other CO2 sequestration sites.

Review on Advances and Prospectives of Direct Air Capture: Thermodynamic Verification, Optimized Material Selection, and Technical Economic Assessment for the Application

“…It is also important to note that the gas injected into the formation is a mixture of CO 2 , N 2 , and O 2 , so it is necessary to carefully consider and monitor its internal reaction and possible environmental influence. 182 In addition, Robert 183 proposed the construction of nano factories, which used nanomolecular filters to separate CO 2 directly from the air. The molecular filter is designed to mimic the mechanism by which proteins are transported by biofilms, ″pulling″ CO 2 into the collector at specific sites.…”

“…In this design, it is not necessary to obtain high-purity CO 2 because the concentration of less than 98% can be directly stored, so it is technically feasible; Economically, their calculations show that storing low concentrations (80%) of CO 2 at a depth of 1,500 m costs about twice as much as high concentrations (99%), which means that the capture cost of a low concentration is less than half that of a high concentration to be economical. It is also important to note that the gas injected into the formation is a mixture of CO 2 , N 2 , and O 2 , so it is necessary to carefully consider and monitor its internal reaction and possible environmental influence . In addition, Robert proposed the construction of nano factories, which used nanomolecular filters to separate CO 2 directly from the air.…”

Continuous monitoring system for safe managements of CO2 storage and geothermal reservoirs

“…SNR = -./ / 12. , (7) where ε is the signal or noise level, f is the frequency, X is the amplitude in each channel, and N is the number of channels. Note the amplitudes of the signal channel |X(fsig)| include both signal and noise.…”

“…To achieve such a large number of CO2 storage sites, we should manage multi CO2 storage reservoirs in extensive areas using an innovative monitoring system for the stored CO2. Monitoring injected CO2 in its reservoir is crucial for predicting the risk of CO2 leakage, increasing efficiency, reducing the cost of CO2 storage, and reducing the risk of induced seismicity 6, 7 . Also, the information derived from monitoring is vital to obtain public acceptance for the projects.…”