Earthquake source parameter analysis shows hydraulic fracturing induced events are consistent with fault reactivation under regional stress in northeastern British Columbia, Canada

2020 ◽  
Author(s):  
Marco Pascal Roth ◽  
Alessandro Verdecchia ◽  
Kilian B. Kemna ◽  
John Onwuemeka ◽  
Rebecca M. Harrington ◽  
...  
Keyword(s):  
British Columbia ◽  
Hydraulic Fracturing ◽  
Focal Mechanism ◽  
Seismic Moment ◽  
Parameter Analysis ◽  
Active Time ◽  
Regional Stress ◽  
Seismic Stations ◽  
Stress Orientation ◽  
Time Periods

<p>An increasing number of M3+ earthquakes have been associated with Hydraulic Fracturing (HF) injection activity in low-permeable tight shale formations in the Western Canada Sedimentary Basin (WCSB) in the last decade. These include a M<sub>w </sub>4.6 on 08/17/2015 near Ft. St. John, a M<sub>L</sub> 4.5 on 11/30/2018, and two M<sub>L</sub> 3.2 on 10/05/2019, 10/08/2019 near Dawson Creek, British Columbia. Increased seismic activity in the Dawson-Septimus area prompted a temporary deployment of seismic stations in a joint effort between McGill University and the Ruhr University Bochum in order to perform higher-resolution monitoring relative to the regional seismic station coverage. Here, we use waveform data from that deployment of 22 (dominantly broadband) stations in close proximity to numerous HF wells in an area of roughly 60 x 70 km<sup>2</sup>, between July 2017 and August 2019, as well as records from 6 additional seismic stations northwest of the study area. In total, we detect 6222 local earthquakes, of which 5325 surpass a quality control criterion of having a horizontal location error ≤ 3 km. An investigation of the spatial and temporal correlation between injection and earthquake initiation using a cross-correlation based event similarity analysis during seismically active time periods reveals a high degree of event similarity within various clusters and a strong correlation with individual injection episodes at specific HF wells. In addition, event clusters also exhibit similar patterns in daily cumulative seismic moment, independent of differences in waveform characteristics.</p><p>As individual clusters may represent the activation of specific geological structures, we perform double-difference relative relocation of seismicity to identify fault orientations. In addition, we invert for focal mechanism solutions per event cluster to check consistency with structures inferred with relocated hypocenters, and perform spectral fitting for source parameter analysis. Event relocations are performed on individual families, where the total catalog is divided into subsets corresponding to 24 seismic active time periods where 43 event families are active. Relocating each earthquake family separately allows us to successfully relocate 4571 out of the total 5325 events. The relative relocations align in two dominant orientations, with one roughly perpendicular to the maximum horizontal regional stress orientation, and the other at low angles to the maximum regional stress orientation on a regional scale around individual HF wells. Focal mechanism estimates for events with M > 2.0 result in two primary groups of faulting mechanisms: strike-slip deformation on faults implied by lineations striking at low angles to S<sub>H</sub>, and thrust-faulting deformation on faults implied by lineations perpendicular to S<sub>H</sub>. Seismic moment and corner frequency estimates from single spectrum and spectral ratio fitting as well as scaling relations will be presented.</p>

High-Resolution Imaging of Hydraulic-Fracturing-Induced Earthquake Clusters in the Dawson-Septimus Area, Northeast British Columbia, Canada

2020 ◽  
Vol 91 (5) ◽  
pp. 2744-2756 ◽  
Author(s):  
Marco P. Roth ◽  
Alessandro Verdecchia ◽  
Rebecca M. Harrington ◽  
Yajing Liu
Keyword(s):  
British Columbia ◽  
Hydraulic Fracturing ◽  
Regional Scale ◽  
Double Difference ◽  
Multiple Fractures ◽  
Waveform Data ◽  
Regional Stress ◽  
Western Canada Sedimentary Basin ◽  
Well Stimulation ◽  
Montney Formation

Abstract The number of earthquakes in the western Canada sedimentary basin (WCSB) has increased drastically in the last decade related to unconventional energy production. The majority of reported earthquakes are correlated spatially and temporally with hydraulic fracturing (HF) well stimulation. In this study, we use waveform data from a new deployment of 15 broadband seismic stations in a spatial area of roughly 60×70km2, covering parts of the Montney Formation, to study the relationship between earthquakes and HF operations in the Dawson-Septimus area, British Columbia, Canada, where the two largest HF-related earthquakes in WCSB to date, an Mw 4.6 on 17 August 2015 and an ML 4.5 on 30 November 2018, have occurred. We use an automated short-term average/long-term average algorithm and the SeisComP3-software to detect and locate 5757 local earthquakes between 1 July 2017 and 30 April 2019. Using two clustering techniques and double-difference relocations of the initial catalog, we define event families that are spatially associated with specific wells, and exhibit temporal migration along a horizontal well bore and/or multiple fractures close to wells. Relocated clusters align in two dominant orientations: one roughly perpendicular to the maximum horizontal regional stress direction (SH) and several conjugate structures at low angles to SH. Comparing the two predominant seismicity lineations to regional earthquake focal mechanisms suggests that deformation occurs via thrust faulting with fault strike oriented perpendicular to SH and via strike-slip faulting with strike azimuth at low angles to SH. Local scale seismicity patterns exhibit clustering around individual HF wells, whereas regional scale patterns form lineations consistent with deformation on faults optimally oriented in the regional stress field.

scholarly journals The comparative analysis of 2018 Alaska earthquakes from surface wave records

2020 ◽  
Vol 2 (1) ◽  
pp. 76-84
Author(s):  
Anastasiya Fomochkina ◽  
Boris Bukchin
Keyword(s):  
Surface Wave ◽  
Focal Mechanism ◽  
Seismic Moment ◽  
Optimal Solution ◽  
Seismic Source ◽  
P Wave ◽  
Wave Spectra ◽  
Earthquake Intensity ◽  
Second Moments ◽  
First Arrival

We consider the source of an earthquake in an approximation of instant point shift dislocation. Such a source is given by its depth, the focal mechanism determined by three angles (strike, dip, and slip), and the seismic moment characterizing the earthquake intensity. We determine the source depth and focal mechanism by a systematic exploration of 4D parametric space, and seismic moment - by solving the problem of minimization of the misfit between observed and calculated surface wave spectra for every combination of all other parameters. As is well known, the focal mechanism cannot be uniquely determined from the surface wave’s amplitude spectra only. We used P-wave first arrival polarities to select the optimal solution. Ana-lyzing the surface wave spectra at shorter periods, we describe the source in an approximation of the stress glut second moments. Using these moments we determine integral estimates of the geometry, the duration of the seismic source, and rupture propagation. The results of the application of this technique for two Alaska earthquakes that occurred in 2018 (with Mw7.9 in January and with Mw7.1 in November) are presented. The possibility of the fault plane identification, which based on the obtained estimates of the focal mechanisms and second mo-ments, is analyzed for both events. Bilateral model of the source is constructed.

Source mechanism of two 1994 intermediate-depth-focus earthquakes in Guerrero, Mexico

1999 ◽  
Vol 89 (4) ◽  
pp. 1004-1018
Author(s):  
Luis Quintanar ◽  
J. Yamamoto ◽  
Z. Jiménez
Keyword(s):  
Focal Mechanism ◽  
Seismic Moment ◽  
P Wave ◽  
Focal Mechanism Solution ◽  
Medium Size ◽  
Small Contribution ◽  
Normal Faulting ◽  
Intermediate Depth ◽  
Double Couple ◽  
First Motion

Abstract In May and December 1994, two medium-size, intermediate-depth-focus earthquakes occurred in Guerrero, Mexico, eastward of the rupture area of the great Michoacan earthquake of September 19, 1985. Even though these are not major earthquakes (∼6.4 Mw), they were widely felt through central and southern Mexico, with minor damage at Zihuatanejo and Acapulco, located along the Pacific coast, and Mexico City. Both earthquakes, separated by ∼100 km, have similar focal depths and magnitudes, however, their focal mechanisms, based upon the polarities of first arrivals, show some differences. The May earthquake shows a clear normal faulting mechanism (φ = 307°, δ = 55°, λ = −108°), whereas the December earthquake mechanism solution suggests an initial thrust faulting (φ = 313°, δ = 62°, λ = 98°) process. Although previous analysis, including local and teleseismic stations, reported a normal faulting for the December earthquake, we find that modeling using the CMT focal mechanism solution fails to reproduce the first 5 sec of the observed P-wave signal at the nearest broadband station (Δ = 168 km) and the S-wave polarity at two strong ground-motion local stations (Δ = 32, 53 km); in fact, the best fit for these stations is obtained using the thrust focal mechanism calculated from the first-motion method. Seismic moment value and rupture duration time deduced from the teleseismic spectral analysis are: 2.0 × 1018 N-m and 6.9 sec for the May event; 2.8 × 1018 N-m and 7.1 sec for the December earthquake. From the inferred seismic moment, an average Δσ of ∼15 bars for both earthquakes is obtained. Inversion of teleseismic P-wave data indicates a better fit using the CMT focal mechanism solution (normal faulting) than the first-motion mechanism for both earthquakes, although the adjustment's differences are small for the May event; for this earthquake, the rupture consisted of two sources separated by ∼7 sec, starting at a depth of ∼40 km and then propagating downdip, reaching a depth of ∼60 km. The December earthquake however, released, all its energy at a depth of 50 km in two main sources separated by ∼10 sec. The non-double-couple components values are −0.004 and −0.01 for the May and December events, respectively, indicating that the December shock has a small contribution of non-double-couple radiation that could be the result of a changing mechanism. This result agrees with the hypothesis that a slab subducting at a shallower angle (our case) is associated with the existence of random subfaults with different fault orientations. From a tectonic point of view, the complexity of the December earthquake could be the result of the observed complexity of the stress distribution around 101°W and the existence of compressional events beneath the normal faulting earthquakes near the coastline. This feature permits the flexural stresses associated to the slab bending upward to become subhorizontal at the Guerrero region. We conclude that the May earthquake corresponds to a pure normal faulting, whereas the December shock is a complex event with a variable fault geometry.

Well-Log-Based Velocity and Density Models for the Montney Unconventional Resource Play in Northeast British Columbia, Canada, Applicable to Induced Seismicity Monitoring and Research

2020 ◽  
Author(s):  
Alireza Babaie Mahani ◽  
Dmytro Malytskyy ◽  
Ryan Visser ◽  
Mark Hayes ◽  
Michelle Gaucher ◽  
...  
Keyword(s):  
British Columbia ◽  
Hydraulic Fracturing ◽  
Cross Sections ◽  
Induced Seismicity ◽  
Focal Depth ◽  
Depth Resolution ◽  
Velocity Model ◽  
The North ◽  
Seismicity Monitoring ◽  
Unconventional Resource

Abstract We present detailed velocity and density models for the Montney unconventional resource play in northeast British Columbia, Canada. The new models are specifically essential for robust hypocenter determination in the areas undergoing multistage hydraulic-fracturing operations and for detailed analysis of induced seismicity processes in the region. For the upper 4 km of the sedimentary structure, we review hundreds of well logs and select sonic and density logs from 19 locations to build the representative models. For depths below 4 km, we extend our models using data from the southern Alberta refraction experiment (Clowes et al., 2002). We provide one set of models for the entire Montney play along with two separated sets for the southern and northern areas. Specifically, the models for the southern and northern Montney play are based on logs located in and around the Kiskatinaw Seismic Monitoring and Mitigation Area and the North Peace Ground Motion Monitoring area, respectively. To demonstrate the usefulness of our detailed velocity model, we compare the hypocenter location of earthquakes that occurred within the Montney play as determined with our model and the simple two-layered model (CN01) routinely used by Natural Resources Canada. Locations obtained by our velocity model cluster more tightly with the majority of events having root mean square residual of <0.2  s compared with that of <0.4  s when the CN01 model is used. Cross sections of seismicity versus depth across the area also show significant improvements in the determination of focal depths. Our model results in a reasonable median focal depth of ∼2  km for events in this area, which is consistent with the completion depths of hydraulic-fracturing operations. In comparison, most solutions determined with the CN01 model have fixed focal depths (0 km) due to the lack of depth resolution.

Initiation and Extension of Hydraulic Fractures in Rocks

1967 ◽  
Vol 7 (03) ◽  
pp. 310-318 ◽  
Author(s):  
Bezalel Haimson ◽  
Charles Fairhurst
Keyword(s):  
Fluid Flow ◽  
Hydraulic Fracturing ◽  
Cross Section ◽  
Elastic Constants ◽  
Fluid Pressure ◽  
Principal Stresses ◽  
Regional Stress ◽  
Flow Through ◽  
Elastic Rock ◽  
Regional Stresses

Abstract A criterion is proposed for the initiation of vertical hydraulic fracturing taking into consideration the three stress fields around the wellbore. These fields arise fromnonhydrostatic regional stresses in earththe difference between the fluid pressure in the wellbore and the formation fluid pressure andthe radial fluid flow through porous rock from the wellbore into the formation due to this pressure difference. The wellbore fluid pressure required to initiate a fracture (assuming elastic rock and a smooth wellbore wall) is a function o/ the porous elastic constants of the rock, the two unequal horizontal principal regional caresses, the tensile strength of the rock and the formation fluid pressure. A constant injection rate will extend the fracture to a point where equilibrium is reached and then, to keep the fracture open, the pressure required is a function of the porous elastic constants of the rock, the component of the regional stress normal to the plane of the fracture, the formation fluid pressure and the dimensions of the crack. The same expression may also be used to estimate the vertical fracture width, provided all other variables are known. The derived equations for the initiation and extension pressures in vertical fracturing may be employed to solve for the two horizontal, regional, principal stresses in the rock. Introduction Well stimulation by hydraulic fracturing is a common practice today in the petroleum industry. However, this stimulation process is not a guaranteed success; hence, the deep interest shown by the petroleum companies in better 'understanding the mechanism that brings about rock fracturing, fracture extension and productivity increase. Geologists and mining people became interested in hydraulic fracturing from a different point of view: the method may possibly be employed to determine the magnitude and direction of the principal stresses of great depth. Numerous articles in past years have dealt with the theory of hydraulic fracturing, but they all seem to underestimate the effect of stresses around the wellbore due to penetration of some of the injected fluid into the porous formation. Excellent papers on stresses in porous materials due to fluid flow have been published but no real attempt has been made to show the effect of these stresses in the form of a more complete criterion for vertical hydraulic fracturing initiation and extension. This paper is such an attempt. ASSUMPTIONS It is assumed that rock in the oil-bearing formation is elastic, porous, isotropic and homogeneous. The formation is under a nonhydrostatic state of regional stress with one of the principal regional stresses acting parallel to the vertical axis of the wellbore. This assumption is justified in areas where rock formations do not dip at steep angles and where the surface of the earth is relatively flat. This vertical principal regional stress equals the pressure of the overlying rock, i.e. S33= -pD where S33 is the total vertical principal stress (positive for tension), p is average density of the overlying material and D is the depth of the point where S 33 is calculated. The wellbore wall in the formation is considered to be smooth and circular in cross-section. The fluid flow through the porous elastic rock obeys Darcy's law. The whole medium is looked upon as an infinitely long cylinder with its axis along the axis of the wellbore. The radius of the cylinder is also very large. Over the range of depth at which the oil-bearing formation occurs, it will be assumed that any horizontal cross-section of the cylinder is subjected to the same stress distribution, and likewise that it will deform in the same manner. SPEJ P. 310ˆ

Defusing Technology:Technology Diffusion in British Columbia

1993 ◽  
Vol 9 (1) ◽  
pp. 46-61 ◽  
Author(s):  
Arminée Kazanjian ◽  
Kathryn Friesen
Keyword(s):  
British Columbia ◽  
Historical Data ◽  
Current Data ◽  
Fiscal Year ◽  
Data Sets ◽  
Canadian Province ◽  
Data Set ◽  
Time Periods ◽  
Institutional Profile ◽  
Areas Of Interest

AbstractIn order to explore the diffusion of the selected technologies in one Canadian province (British Columbia), two administrative data sets were analyzed. The data included over 40 million payment records for each fiscal year on medical services provided to British Columbia residents (2,968,769 in 1988) and information on physical facilities, services, and personnel from 138 hospitals in the province. Three specific time periods were examined in each data set, starting with 1979–80 and ending with the most current data available at the time. The detailed retrospective analysis of laboratory and imaging technologies provides historical data in three areas of interest: (a) patterns of diffusion and volume of utilization, (b) institutional profile, and (c) provider profile. The framework for the analysis focused, where possible, on the examination of determinants of diffusion that may be amenable to policy influence.

Hydraulic fracturing operations within an extremely complex stress regime: The case of Fort St. John, British Columbia, Canada

2020 ◽  
Author(s):  
Rebecca O. Salvage ◽  
David W. Eaton
Keyword(s):  
British Columbia ◽  
Hydraulic Fracturing ◽  
Large Scale ◽  
Vertical Plane ◽  
Local Stress ◽  
Complex Stress ◽  
Tectonic Structures ◽  
Principal Stresses ◽  
Stress Regime ◽  
North West

<p>On 30 November 2018, three felt earthquakes occurred in quick succession close to the city of Fort St. John, British Columbia, likely as a direct response to a hydraulic fracturing operation in the area. Events appear tightly clustered spatially within the upper 10 km of the crust. Hypocenters locate at the confluence between a large scale reverse faulting regime (in the north-west, probably due to the influence of the Rocky Mountain fold and thrust belt) and an oblique strike slip faulting regime (in the south-east, probably due to the influence of the Fort St. John Graben), resulting in a variety of focal mechanisms and a very complex local stress regime. Further analysis of the principal stresses suggests that σ<sub>1</sub> is well constrained and close to horizontal, whereas σ<sub>2</sub> and σ<sub>3</sub> are poorly constrained, and can alternate between the horizontal and the vertical plane. Here, we present an overview of the temporal and spatial evolution of this seismic sequence and its relationship to hydraulic fracturing operations in the area, and examine the influence of large-scale regional tectonic structures on the generation of seismicity on this occasion.</p><p> </p>

Experiment Study on Focal Mechanism Inversion of Shale Hydraulic Fracturing: Influence of Attenuation Changes

2017 ◽  
Author(s):  
Hongyu Zhai* ◽  
Xu Chang ◽  
Yibo Wang ◽  
Ziqiu Xue ◽  
Yi Zhang ◽  
...  
Keyword(s):  
Hydraulic Fracturing ◽  
Focal Mechanism ◽  
Experiment Study
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