scholarly journals Effects of long-term fluid injection on induced seismicity parameters and maximum magnitude in northwestern part of The Geysers geothermal field

2015 ◽  
Vol 120 (10) ◽  
pp. 7085-7101 ◽  
Author(s):  
Grzegorz Kwiatek ◽  
Patricia Martínez-Garzón ◽  
Georg Dresen ◽  
Marco Bohnhoff ◽  
Hiroki Sone ◽  
...  
Keyword(s):  
Induced Seismicity ◽  
Geothermal Field ◽  
Fluid Injection ◽  
Northwestern Part ◽  
Maximum Magnitude ◽  
Seismicity Parameters ◽  
The Geysers

scholarly journals Spatial and temporal multiplet analysis for identification of dominant fluid migration path at The Geysers geothermal field, California

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
M. Staszek ◽  
Ł. Rudziński ◽  
G. Kwiatek
Keyword(s):  
Temporal Analysis ◽  
Geothermal Field ◽  
Fluid Injection ◽  
Fluid Migration ◽  
Multiple Events ◽  
Spatial And Temporal Analysis ◽  
Hydraulic Conditions ◽  
The Geysers ◽  
Multiplet Analysis

AbstractMultiplet analysis is based on the identification of seismic events with very similar waveforms which are used then to enhance seismological analysis e.g. by precise relocation of sources. In underground fluid injection conditions, it is a tool frequently used for imaging of subsurface fracture system. We identify over 150 repeatedly activated seismic sources within seismicity cluster induced by fluid injection in NW part of The Geysers geothermal field (California). Majority of multiple events (ME) occur along N–S oriented planar structure which we interpret as a fault plane. Remaining ME are distributed along structures interpreted as fractures, forming together a system of interconnected cracks enabling fluid migration. Temporal analysis reveals that during periods of relatively low fluid injection the proportion of ME to non-multiple events is higher than during periods of high injection. Moreover, ME which occur within the fault differ in activity rate and source properties from ME designating the fractures and non-multiple events. In this study we utilize observed differences between ME occurring within various structures and non-multiple events to describe hydraulic conditions within the reservoir. We show that spatial and temporal analysis of multiplets can be used for identification and characterization of dominant fluid migration paths.

Reservoir conditions related to induced seismicity at the Geysers steam reservoir, northern California

1982 ◽  
Vol 72 (4) ◽  
pp. 1317-1327
Author(s):  
Roger P. Denlinger ◽  
Charles G. Bufe
Keyword(s):  
Induced Seismicity ◽  
Fluid Injection ◽  
Shear Stresses ◽  
Earthquake Activity ◽  
Fractured Reservoir ◽  
Stick Slip ◽  
State Process ◽  
Fracture Systems ◽  
Reservoir Conditions ◽  
The Geysers

abstract Seismicity at The Geysers appears to be induced by steam production, in which water boils to steam within a pervasively fractured reservoir subject to high levels of tectonic shear stresses and strains. The steam reservoir is composed of fractured Franciscan graywacke with a very heterogeneous, multiple permeability and porosity distribution. Permeability is controlled by the larger fracture systems of the reservoir, which act as a very permeable conduit to less permeable rock containing liquid water. The reservoir fluid remains close to the liquidus conditions during production, implying both a temperature and pressure decline in the rock matrix bounding the fracture systems as the reservoir is depleted. Reservoir earthquake focal mechanisms are nearly aligned with the regional tectonic strain field, and reservoir earthquakes are indistinguishable from tectonic earthquakes elsewhere in the region. Within the reservoir, the volume defined by the earthquakes has not changed within the resolution of the seismic network from 1975 to 1979. The log moment per earthquake also has not changed, suggesting a steady-state process of stress buildup and release. Added to the zero correlation of the fluid injection history with the earthquake activity, the above observations suggest that elevated pore pressures and fluid injection are not likely causes for The Geysers induced seismicity. Instead, all available evidence points to the association of induced seismicity with pore pressure and temperature declines. The two most likely mechanisms are either an increase in local shear stress levels with fissure deflation, or a transition from stable to unstable sliding (“stick-slip”). No other documented mechanism for induced seismicity are consistent with in situ reservoir conditions at The Geysers.

scholarly journals Impact of fluid injection on fracture reactivation at The Geysers geothermal field

2016 ◽  
Vol 121 (10) ◽  
pp. 7432-7449 ◽  
Author(s):  
Patricia Martínez-Garzón ◽  
Grzegorz Kwiatek ◽  
Marco Bohnhoff ◽  
Georg Dresen
Keyword(s):  
Geothermal Field ◽  
Fluid Injection ◽  
Fracture Reactivation ◽  
The Geysers

Magnitude distribution complexity and variation at The Geysers geothermal field

2020 ◽  
Vol 222 (2) ◽  
pp. 893-906
Author(s):  
Konstantinos Leptokaropoulos
Keyword(s):  
Seismic Hazard ◽  
Size Distribution ◽  
Hazard Assessment ◽  
Seismic Hazard Assessment ◽  
B Value ◽  
Geothermal Field ◽  
Earthquake Magnitude ◽  
Fluid Injection ◽  
Magnitude Distribution ◽  
The Geysers

SUMMARY Earthquake magnitude (size) distribution is a major component required for seismic hazard assessment and therefore, the accurate determination of its functional shape and variation is a task of utmost importance. Although often considered as stationary, the magnitude distribution at particular sites may significantly vary over time and space. In this study, the well-known Gutenberg–Richter (GR) law, which is widely assumed to describe earthquake magnitude distribution, is tested for a case study of seismicity induced by fluid injection at The Geysers (CA, USA) geothermal field. Statistical tests are developed and applied in order to characterize the magnitude distribution of a high quality catalogue comprising seismicity directly associated with two injection wells, at the north western part of The Geysers. The events size distribution variation is investigated with respect to spatial, temporal, fluid injection and magnitude cut-off criteria. A thorough spatio-temporal analysis is performed for defining seismicity Clusters demonstrating characteristic magnitude distributions which significantly differ from the ones of the nearby Clusters. The magnitude distributions of the entire seismic population as well as of the individual Clusters are tested for their complexity in terms of exponentiality, multimodal and multibump structure. Then, the Clusters identified are further processed and their characteristics are determined in connection to injection rate fluctuations. The results of the analysis clearly indicate that the entire magnitude distribution is definitely complex and non-exponential, whereas subsequent periods demonstrating significantly diverse magnitude distributions are identified. The regional seismicity population is divided into three major families, for one of which exponentiality of magnitude distribution is clearly rejected, whereas for the other two the GR law b-value is directly proportional to fluid injection. In addition, the b-values of these Families seem to be significantly magnitude dependent, a fact that is of major importance for seismic hazard assessment implementations. To conclude, it is strongly suggested that magnitude exponentiality must be tested before proceeding to any b-value calculations, particularly in anthropogenic seismicity cases where complex and time changeable processes take place.

scholarly journals Spatiotemporal changes, faulting regimes, and source parameters of induced seismicity: A case study from The Geysers geothermal field

2014 ◽  
Vol 119 (11) ◽  
pp. 8378-8396 ◽  
Author(s):  
Patricia Martínez-Garzón ◽  
Grzegorz Kwiatek ◽  
Hiroki Sone ◽  
Marco Bohnhoff ◽  
Georg Dresen ◽  
...  
Keyword(s):  
Induced Seismicity ◽  
Source Parameters ◽  
Geothermal Field ◽  
Spatiotemporal Changes ◽  
The Geysers

scholarly journals Time-Dependent Seismic Hazard Analysis for Induced Seismicity: The Case of St Gallen (Switzerland), Geothermal Field

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2747
Author(s):  
Vincenzo Convertito ◽  
Hossein Ebrahimian ◽  
Ortensia Amoroso ◽  
Fatemeh Jalayer ◽  
Raffaella De Matteis ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Induced Seismicity ◽  
Hazard Analysis ◽  
Geothermal Field ◽  
Seismic Hazard Analysis ◽  
Time Dependent ◽  
Recurrence Time ◽  
Maximum Magnitude ◽  
Small Magnitude

Reliable seismic hazard analyses are crucial to mitigate seismic risk. When dealing with induced seismicity the standard Probabilistic Seismic Hazard Analysis (PSHA) has to be modified because of the peculiar characteristics of the induced events. In particular, the relative shallow depths, small magnitude, a correlation with field operations, and eventually non-Poisson recurrence time. In addition to the well-known problem of estimating the maximum expected magnitude, it is important to take into account how the industrial field operations affect the temporal and spatial distribution of the earthquakes. In fact, during specific stages of the project the seismicity may be hard to be modelled as a Poisson process—as usually done in the standard PSHA—and can cluster near the well or migrate toward hazardous known or—even worse—not known faults. Here we present a technique in which we modify the standard PSHA to compute time-dependent seismic hazard. The technique allows using non-Poisson models (BPT, Weibull, gamma and ETAS) whose parameters are fitted using the seismicity record during distinct stages of the field operations. As a test case, the procedure has been implemented by using data recorded at St. Gallen deep geothermal field, Switzerland, during fluid injection. The results suggest that seismic hazard analyses, using appropriate recurrence model, ground motion predictive equations, and maximum magnitude allow the expected ground-motion to be reliably predicted in the study area. The predictions can support site managers to decide how to proceed with the project avoiding adverse consequences.

scholarly journals Evolution of seismicity in relation to fluid injection in the North-Western part of The Geysers geothermal field

2017 ◽  
Vol 212 (2) ◽  
pp. 1157-1166 ◽  
Author(s):  
Konstantinos Leptokaropoulos ◽  
Monika Staszek ◽  
Stanisław Lasocki ◽  
Patricia Martínez-Garzón ◽  
Grzegorz Kwiatek
Keyword(s):  
Geothermal Field ◽  
Fluid Injection ◽  
The North ◽  
The Geysers ◽  
North Western
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