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.

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 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

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

High injection rates decrease the probability of creating undesired, far-reaching fluid migration pathways at Cooper Basin geothermal field

2021 ◽  
Author(s):  
Elvira Battimelli ◽  
Stanisław Lasocki ◽  
Paolo Capuano
Keyword(s):  
Geothermal Field ◽  
Injection Rate ◽  
Seismic Events ◽  
Fluid Migration ◽  
Wellhead Pressure ◽  
High Injection ◽  
The Geysers ◽  
Migration Pathways ◽  
Cooper Basin ◽  
Injection Rates

<p>Enhanced Geothermal Systems apply the pressurized fluid injection to fracture impermeable rocks to form pathways in which water circulates. The cold water under high pressure is pumped into the hot subsoil, where it heats up and returns to the surface. However, the induced fractures may coalesce into unwanted paths that allow the fluids to reach pre-existing faults, triggering major seismic events.</p><p>This work investigates the relationship between injection and a degree of disordering of sources, ZZ, at Cooper Basin geothermal field in Australia, following the methodology developed and applied to study The Geysers geothermal field case (Lasocki & Orlecka-Sikora, 2020). The parameter ZZ quantifies the potential of seismicity to build pathways for fluid migration. It is the average distance between the seismic events in the eight-dimensional parameter space consisting of three hypocentral coordinates, T- and P-axis plunges, T-axis trend, and polar and azimuthal angles in the spherical system of coordinates beginning at the open hole of an injection well. A decrease of ZZ indicates an increasing hazard of forming far-reaching migration pathways. In The Geysers case, ZZ turned out to be highly correlated with the injection rate.</p><p>Here we focus on the case of Habanero 4 well stimulation from 17 - November 30, 2012 (data access, see: IS EPOS, 2020). We processed 489 seismic events with known focal mechanisms. The events moment magnitude varies between 0.8 and 3.1.  </p><p>Our analysis shows that ZZ is significantly correlated with both the injection rate and the wellhead pressure. The higher the injection rate / the wellhead pressure was, the less probable was the creation of undesired fluid migration pathways. The Cooper Basin’s and The Geyser’s reservoir rocks are vastly different, the former – granite, the latter – greywacke sandstone, likewise the stimulation techniques applied in these two reservoirs. However, in both cases, ZZ was positively correlated with injection rate; thus, the potential to build unwanted paths for fluids was negatively correlated. These results suggest that such correlation may be a global feature of rock fracturing caused by pressurized fluid injections.</p><p><em>This work has been supported by S4CE (Science for Clean Energy) project, funded from the European Union’s Horizon 2020 - Framework Programme, under grant agreement No 764810 and by PRIN-MATISSE (20177EPPN2) project funded by Italian Ministry of Education and Research.</em></p><p> </p><p><strong>References:</strong></p><p>IS EPOS (2020), Episode: COOPER BASIN, https://tcs.ah-epos.eu/#episode:COOPER_BASIN, doi:10.25171/InstGeoph_PAS_ISEPOS-2020-001</p><p>Lasocki, S., & Orlecka-Sikora, B. (2020). High injection rates counteract formation of far-reaching fluid migration pathways at The Geysers geothermal field. Geophysical Research Letters, 47, e2019GL086212. https://doi.org/10.1029/2019GL086212</p>

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