Induced Seismicity at the Preston New Road Shale Gas Site in Lancashire, UK – Site Characterisation and impact on the TLS

2020 ◽  
Author(s):  
Antoine Delvoye ◽  
Ben Edwards
Keyword(s):  
Hydraulic Fracturing ◽  
Hazard Assessment ◽  
Induced Seismicity ◽  
Seismic Hazard Assessment ◽  
Velocity Model ◽  
Ambient Vibration ◽  
Mitigation Measures ◽  
Traffic Light ◽  
British Geological Survey ◽  
Clay Deposits

<div>Recent examples have shown that fluid injection during hydraulic fracturing can result in felt, or even damaging, seismic activity. In the vicinity of the Preston New Road site (Lancashire, UK), almost 200 earthquakes of ML -0.8 to 2.9 have been recorded by the British Geological Survey (BGS) over the period from October 15th 2018 to September 2019. This corresponds to the period during which hydraulic fracturing (fracking) was carried out by the operator, Cuadrilla Resources. Throughout the operation, fracking had to be suspended temporarily five times as the ML 0.5 ‘red light’ of the UK regulatory Traffic Light System (TLS) was exceeded. Since 2017, the University of Liverpool has operated a seismic monitoring network comprising nine broadband Nanometrics Trillium 120 across the Blackpool-Preston region in order to determine the baseline seismicity and monitor induced events associated with the fracking operations atthe site. In addition to this network, both Cuadrilla and the BGS deployedseismometers-including borehole geophone strings-over the region making it oneof the best places in Europe for monitoring induced seismicity. The superficial geology of the region is dominated by thick sand, till and clay deposits, poten-tially leading to significant amplification of seismic waves. This amplification may lead to over-estimation of earthquake magnitude, and therefore increased likelihood of triggering mitigation measures associated with the TLS. In order to understand amplification effects near the PNR site, surface-wave measurements (both MASW and seismic Ambient Vibration Arrays, AVAs) have been used to derive dispersion curves and obtain VS profiles through an inversion process for station-site characterization. By using small local arrays (hundreds of meters wide) to regional arrays (tens of km wide), we reconstruct a velocity model down to the bedrock depth. This velocity model can then be used to compute a parshly non-ergodic ground motion and subsequently seismic hazard assessment. This approach allow us to account for site to site variability and result in reduced uncertainty in the hazard assessment. We find Vs30 in the range 200 – 300 m/s at the sites investigated, leading to significant amplification effects that may bias event magnitudes determined on a surface array.</div>

Experiences and learnings from induced seismicity regulation in Alberta

2018 ◽  
Vol 6 (2) ◽  
pp. SE15-SE21 ◽  
Author(s):  
Todd Shipman ◽  
Ron MacDonald ◽  
Tom Byrnes
Keyword(s):  
Hydraulic Fracturing ◽  
Induced Seismicity ◽  
Red Light ◽  
Seismic Hazard Assessment ◽  
Traffic Light ◽  
Regulatory Requirements ◽  
Current State ◽  
New Information ◽  
Response Plan ◽  
The Town

We have examined the experiences and learnings acquired through the implementation of the Alberta Energy Regulator’s (AER) subsurface order no. 2 (sub or no. 2) traffic light protocol (TLP). On 22 January 2015, a 4.4 [Formula: see text] seismic event occurred near a hydraulic fracturing operation in west-central Alberta and was felt by residents of the town of Fox Creek. On 19 February 2015, the AER issued sub or no. 2 to help manage induced seismicity, as related to hydraulic fracturing of the Duvernay zone in a prescribed area around Fox Creek. Sub or no. 2 requires operators affected by the order to conduct a seismic hazard assessment; prepare a monitoring, mitigation, and response plan; conduct seismic monitoring; and adhere to a TLP. Since sub or no. 2 was issued, two “red light” events (i.e., [Formula: see text]) have occurred in the area. Review and analysis of data and information collected under sub or no. 2 facilitate an improved understanding of the key geologic and operational controls on induced seismicity and allow for an assessment of the efficacy of industry practices and regulatory requirements. We still support the use of local magnitude [Formula: see text] for our TLP based on the purpose and outcomes provided by sub or no. 2. Conversations with operators have suggested that [Formula: see text] orientation should inform the wells’ trajectory with respect to critically stressed faults. The requirement of a response plan was part of the learning process developed under sub or no. 2. Through this exercise, the AER has developed a better understanding of the goals of the response plans, which were better defined through conversations with operators. Sub or no. 2 is consistent with the current state of the evolving science of induced seismicity and has the capacity to change as new information is obtained.

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.

A risk-based approach for managing hydraulic fracturing–induced seismicity

Science ◽  
2021 ◽  
Vol 372 (6541) ◽  
pp. 504-507
Author(s):  
Ryan Schultz ◽  
Gregory C. Beroza ◽  
William L. Ellsworth
Keyword(s):  
Hydraulic Fracturing ◽  
Induced Seismicity ◽  
Red Light ◽  
Maximum Magnitude ◽  
Traffic Light ◽  
Induced Earthquakes ◽  
Eagle Ford Shale ◽  
Eagle Ford ◽  
Sensitivity Tests ◽  
Spatially Varying

Risks from induced earthquakes are a growing concern that needs effective management. For hydraulic fracturing of the Eagle Ford shale in southern Texas, we developed a risk-informed strategy for choosing red-light thresholds that require immediate well shut-in. We used a combination of datasets to simulate spatially heterogeneous nuisance and damage impacts. Simulated impacts are greater in the northeast of the play and smaller in the southwest. This heterogeneity is driven by concentrations of population density. Spatially varying red-light thresholds normalized on these impacts [moment magnitude (Mw) 2.0 to 5.0] are fairer and safer than a single threshold applied over a broad area. Sensitivity tests indicate that the forecast maximum magnitude is the most influential parameter. Our method provides a guideline for traffic light protocols and managing induced seismicity risks.

scholarly journals Real‐Time Imaging, Forecasting, and Management of Human‐Induced Seismicity at Preston New Road, Lancashire, England

2019 ◽  
Author(s):  
Huw Clarke ◽  
James P. Verdon ◽  
Tom Kettlety ◽  
Alan F. Baird ◽  
J‐Michael Kendall
Keyword(s):  
Hydraulic Fracturing ◽  
Real Time ◽  
Shale Gas ◽  
Statistical Models ◽  
Induced Seismicity ◽  
Red Light ◽  
Fracture Network ◽  
Fluid Injection ◽  
Traffic Light ◽  
Subsurface Fluid

ABSTRACTEarthquakes induced by subsurface fluid injection pose a significant issue across a range of industries. Debate continues as to the most effective methods to mitigate the resulting seismic hazard. Observations of induced seismicity indicate that the rate of seismicity scales with the injection volume and that events follow the Gutenberg–Richter distribution. These two inferences permit us to populate statistical models of the seismicity and extrapolate them to make forecasts of the expected event magnitudes as injection continues. Here, we describe a shale gas site where this approach was used in real time to make operational decisions during hydraulic fracturing operations.Microseismic observations revealed the intersection between hydraulic fracturing and a pre‐existing fault or fracture network that became seismically active. Although “red light” events, requiring a pause to the injection program, occurred on several occasions, the observed event magnitudes fell within expected levels based on the extrapolated statistical models, and the levels of seismicity remained within acceptable limits as defined by the regulator. To date, induced seismicity has typically been regulated using retroactive traffic light schemes. This study shows that the use of high‐quality microseismic observations to populate statistical models that forecast expected event magnitudes can provide a more effective approach.

scholarly journals Seismisitas di Wilayah Jawa Tengah dan Sekitarnya Berdasarkan Hasil Relokasi Hiposenter dari Empat Jaringan Seismik Menggunakan Model Kecepatan 3-D

EKSPLORIUM ◽  
2020 ◽  
Vol 41 (1) ◽  
pp. 61
Author(s):  
Mohamad Ramdhan ◽  
Priyobudi Priyobudi ◽  
Said Kristyawan ◽  
Andry Syaly Sembiring
Keyword(s):  
Seismic Hazard ◽  
Hazard Assessment ◽  
Seismic Hazard Assessment ◽  
Velocity Model ◽  
Columnar Structure ◽  
Seismic Zone ◽  
Earthquake Parameters ◽  
Central Java ◽  
Hypocenter Relocation ◽  
Tectonic Study

ABSTRAK Relokasi hiposenter merupakan suatu metode yang digunakan untuk mendapatkan parameter-parameter gempa yang presisi. Parameter-parameter tersebut digunakan untuk studi tektonik lanjut seperti seismic hazard assessment pada suatu area. Penggunan model kecepatan 3-D secara teori akan memberikan hasil yang lebih baik dibandingkan dengan model 1-D karena model kecepatan di bawah permukaan bumi lebih mendekati model 3-D. Sebanyak 767 event gempa yang direkam oleh jaringan seismik DOMERAPI, MERAMEX, BMKG, dan BPPTKG digunakan pada penelitian ini. Gempa-gempa tersebut direlokasi dengan model kecepatan 3-D dan dianalisis untuk studi seismotektonik di wilayah Jawa Tengah dan sekitarnya. Hasil relokasi hiposenter menggunakan model kecepatan 3-D berhasil mendeteksi sejumlah fitur tektonik secara lebih jelas seperti struktur kolom yang berkaitan dengan Struktur backthrust di selatan Kebumen. Penampang vertikal arah barat-timur yang melewati Sesar Opak mengindikasikan arah dip bidang sesarnya ke arah timur. Zona seismik ganda yang terdeteksi pada studi sebelumnya tidak bisa teridentifikasi dengan baik pada studi ini. Sejumlah gempa volcano-tectonic (VT) berkaitan dengan aktivitas magma dangkal Gunung Merapi terdeteksi juga dengan jelas pada studi ini.ABSTRACT Hypocenter relocation is a method used to get precise earthquake parameters. They will be useful for an advanced tectonic study like seismic hazard assessment in an area. The hypocenter relocation using a 3-D velocity model will theoretically obtain better results than a 1-D velocity model because the earth subsurface model is closed with a 3-D model. Some 767 earthquakes recorded by DOMERAPI, MERAMEX, BMKG, and BPPTKG networks used in this research. They were relocated by using a 3-D velocity model and analyzed for seismotectonic study in Central Java area and its surroundings. The result of hypocenter relocation using a 3-D velocity model is successfully detecting some tectonic features more clearly like columnar structure related to the backthrust structure at the south of Kebumen. The west-east vertical cross-section crossing the Opak fault indicates the dip of the fault plane is directing to the east. This study could not identify the double seismic zone, which was detected by the previous research. Some volcano-tectonic (VT) earthquakes related to the shallow magma activity of Mount Merapi also are detected clearly in this study.

scholarly journals Green, yellow, red, or out of the blue? An assessment of Traffic Light Schemes to mitigate the impact of hydraulic fracturing-induced seismicity

2020 ◽  
Author(s):  
James P. Verdon ◽  
Julian J. Bommer
Keyword(s):  
Hydraulic Fracturing ◽  
Induced Seismicity ◽  
Risk Mitigation ◽  
Red Light ◽  
Fundamental Parameter ◽  
Traffic Light ◽  
The Usa ◽  
The Uk ◽  
The Impact ◽  
Magnitude Increase

Abstract Mitigating hydraulic fracturing-induced seismicity (HF-IS) poses a challenge for shale gas companies and regulators alike. The use of Traffic Light Schemes (TLSs) is the most common way by which the hazards associated with HF-IS are mitigated. In this study, we discuss the implicit risk mitigation objectives of TLSs and explain the advantages of magnitude as the fundamental parameter to characterise induced seismic hazard. We go on to investigate some of the key assumptions on which TLSs are based, namely that magnitudes evolve relatively gradually from green to yellow to red thresholds (as opposed to larger events occurring “out-of-the-blue”), and that trailing event magnitudes do not increase substantially after injection stops. We compile HF-IS datasets from around the world, including the USA, Canada, the UK, and China, and track the temporal evolution of magnitudes in order to evaluate the extent to which magnitude jumps (i.e. sharp increases in magnitude from preceding events within a sequence) and trailing events occur. We find in the majority of cases magnitude jumps are less than 2 units. One quarter of cases experienced a post-injection magnitude increase, with the largest being 1.6. Trailing event increases generally occurred soon after injection, with most cases showing no increase in magnitude more than a few days after then end of injection. Hence, the effective operation of TLSs may require red-light thresholds to be set as much as two magnitude units below the threshold that the scheme is intended to avoid.

scholarly journals Development of seismicity and probabilistic hazard assessment for the Groningen gas field

2017 ◽  
Vol 96 (5) ◽  
pp. s235-s245 ◽  
Author(s):  
Bernard Dost ◽  
Elmer Ruigrok ◽  
Jesper Spetzler
Keyword(s):  
Hazard Assessment ◽  
Monitoring Network ◽  
Seismic Hazard Assessment ◽  
Velocity Model ◽  
Probabilistic Seismic Hazard Assessment ◽  
Gas Field ◽  
Ground Motion Model ◽  
Methods Of Calculation ◽  
Source Models ◽  
Groningen Gas Field

AbstractThe increase in number and strength of shallow induced seismicity connected to the Groningen gas field since 2003 and the occurrence of a ML 3.6 event in 2012 started the development of a full probabilistic seismic hazard assessment (PSHA) for Groningen, required by the regulator. Densification of the monitoring network resulted in a decrease of the location threshold and magnitude of completeness down to ~ ML=0.5. Combined with a detailed local velocity model, epicentre accuracy could be reduced from 0.5–1km to 0.1–0.3km and a vertical resolution ~0.3km. Time-dependent seismic activity is observed and taken into account into PSHA calculations. Development of the Ground Motion Model for Groningen resulted in a significant reduction of the hazard. Comparison of different implementations of the PSHA, using different source models, based on either a compaction model and production scenarios or on extrapolation of past seismicity, and methods of calculation, shows similar results.

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