Minimal Clustering of Injection-Induced Earthquakes Observed with a Large-n Seismic Array

2020 ◽  
Vol 110 (5) ◽  
pp. 2005-2017 ◽  
Author(s):  
Elizabeth S. Cochran ◽  
Alexander Wickham-Piotrowski ◽  
Kilian B. Kemna ◽  
Rebecca M. Harrington ◽  
Sara L. Dougherty ◽  
...  
Keyword(s):  
Nearest Neighbor ◽  
Seismic Array ◽  
Seismic Survey ◽  
Single Event ◽  
Induced Earthquakes ◽  
Injection Wells ◽  
Independent Events ◽  
Large N ◽  
Aftershock Sequences ◽  
Stress Changes

ABSTRACT The clustering behavior of injection-induced earthquakes is examined using one month of data recorded by the LArge-n Seismic Survey in Oklahoma (LASSO) array. The 1829-node seismic array was deployed in a 25  km×32  km area of active saltwater disposal in northern Oklahoma between 14 April and 10 May 2016. Injection rates in the study area are nearly constant around the time of the deployment. We develop a local magnitude (ML) equation for the region and estimate magnitudes for 1104 earthquakes recorded by the deployment. The determined earthquake magnitudes range from ML 0.01 to 3.0. The majority of earthquakes occurred between 1.5 and 5.5 km depth, and the shallowest earthquake depths overlap with the base of injection wells at depths between 1.5 and 2.5 km. We compute focal mechanisms of the largest events (ML>2.0), and find a mix of normal- and strike-slip-faulting types. Earthquakes occur regularly in time during the deployment, but are not evenly distributed in space across the study area, that is, they are spatially clustered. Analysis of the nearest-neighbor distances in the space–time–magnitude domain shows the seismicity is dominated by single-event clusters (i.e., independent events). This high proportion of single-event clusters compared with multievent clusters has been previously noted for induced events at geothermal sites. When clustering occurs, the number of events in a cluster is typically small. We observe only four clusters with 10 or more events. For these larger clusters, we find equivalent numbers of foreshocks and aftershocks; however, the foreshock sequences are significantly longer in duration lasting days to tens of days, while aftershock sequences are observed only on the order of one day. The minimal clustering observed for events in the LASSO array suggests that the majority of events are being directly driven by stress changes due to local saltwater disposal.

USING A LARGE-N SEISMIC ARRAY TO EXPLORE INJECTION-INDUCED EARTHQUAKES IN NORTHERN OKLAHOMA

2019 ◽  
Author(s):  
Elizabeth S. Cochran ◽  
◽  
Rebecca Harrington ◽  
Sara Dougherty ◽  
Andres Peña-Castro ◽  
...  
Keyword(s):  
Seismic Array ◽  
Induced Earthquakes ◽  
Large N

scholarly journals S-wave experiments for the exploration of a deep geothermal carbonate reservoir in the German Molasse Basin

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Britta Wawerzinek ◽  
Hermann Buness ◽  
Hartwig von Hartmann ◽  
David C. Tanner
Keyword(s):  
Upper Jurassic ◽  
Carbonate Reservoir ◽  
P Wave ◽  
Seismic Survey ◽  
Seismic Exploration ◽  
Molasse Basin ◽  
S Wave ◽  
Induced Earthquakes ◽  
Conversion Point ◽  
Facies Classification

AbstractThere are many successful geothermal projects that exploit the Upper Jurassic aquifer at 2–3 km depth in the German Molasse Basin. However, up to now, only P-wave seismic exploration has been carried out. In an experiment in the Greater Munich area, we recorded S-waves that were generated by the conventional P-wave seismic survey, using 3C receivers. From this, we built a 3D volume of P- to S-converted (PS) waves using the asymptotic conversion point approach. By combining the P-volume and the resulting PS-seismic volume, we were able to derive the spatial distribution of the vp/vs ratio of both the Molasse overburden and the Upper Jurassic reservoir. We found that the vp/vs ratios for the Molasse units range from 2.0 to 2.3 with a median of 2.15, which is much higher than previously assumed. This raises the depth of hypocenters of induced earthquakes in surrounding geothermal wells. The vp/vs ratios found in the Upper Jurassic vary laterally between 1.5 and 2.2. Since no boreholes are available for verification, we test our results against an independently derived facies classification of the conventional 3D seismic volume and found it correlates well. Furthermore, we see that low vp/vs ratios correlate with high vp and vs velocities. We interpret the latter as dolomitized rocks, which are connected with enhanced permeability in the reservoir. We conclude that 3C registration of conventional P-wave surveys is worthwhile.

Overcoming CO2 Injector Well Design and Completion Challenges in a Carbonate Reservoir for World's First Offshore Carbon Capture Storage CCS SE Asia Project

2021 ◽  
Author(s):  
Mahesh S. Picha ◽  
M. Azuan B. Abu Bakar ◽  
Parimal A. Patil ◽  
Faiz A. Abu Bakar ◽  
Debasis P. Das ◽  
...  
Keyword(s):  
Carbon Capture ◽  
Injection Pressure ◽  
Co2 Concentration ◽  
Carbonate Reservoir ◽  
Seismic Survey ◽  
Co2 Injection ◽  
Injection Wells ◽  
Gas Field ◽  
Accelerated Corrosion ◽  
Well Design

Abstract Oil & Gas Operators are focusing on zero carbon emission to comply with government's changing rules and regulations, which play an important role in the encouragement of carbon capture initiatives. This paper aims to give insights on the world's first offshore CCS project in carbonate reservoir, where wells will be drilled to inject CO2, and store produced CO2 from contaminated fields. To safeguard the storage containment, the integrity of all wells needs to be scrutinized. Development wells in the identified depleted gas field are more than 40 years old and were not designed with consideration of high CO2 concentration in the reservoir. In consequence, the possibility of well leakage due to accelerated corrosion channeling and cracks, along the wellbore cannot be ignored and require careful evaluation. Rigorous process has been adopted in assessing the feasibility for converting existing gas producers into CO2 injectors. The required defined basis of designs for gas producer and CO2 injection wells differs in a great extent and this governs the re-usability of wells for CO2 injection or necessity to be abandoned. Three (3) new CO2 injectors with fat to slim design approach, corrosion resistant alloy (CRA) material and CO2 resistant cement are designed in view to achieve lifecycle integrity. Optimum angle of 53 deg and maintaining the injection pressure of 50 bar at 90 MSCFD rate is required for the injection of supercritical CO2 for 20 years. During well execution, challenges such as anti-collision risk, total loss scenarios while drilling in Carbonate reservoir need to be addressed before execution. The completion design is also focusing on having minimal number of completion jewelries to reduce pressure differential and potential leak paths from tubing hangar down to the end of lower completion. The selection of downhole safety valve (TRSV) type is of high importance to accommodate CO2 phase attributes at different pressure/temperature. Fiber Optic is included for monitoring the migration of CO2 plume by acquiring seismic survey and for well integrity by analyzing DAS/DTS data.

DYNAMICS OF ENTANGLEMENT IN HEISENBERG CHAINS WITH ASYMMETRIC DZYALOSHINSKII–MORIYA INTERACTIONS

2011 ◽  
Vol 09 (02) ◽  
pp. 751-761 ◽  
Author(s):  
Y. Z. WU ◽  
J. REN ◽  
X. F. JIANG
Keyword(s):  
Nearest Neighbor ◽  
Time Interval ◽  
Dm Interaction ◽  
Large N ◽  
Heisenberg Chains

Dynamics of the nearest-neighbor concurrence and the block–block entanglement in closed Heisenberg chains with Dzyaloshinskii–Moriya (DM) interactions are simulated numerically. It is found that the nearest-neighbor concurrence and the block–block entanglement can be generated dynamically from an initial antiferromagnetic (AF) state, and DM interactions will enhance the amplitude of oscillation of concurrence and that of block–block entanglement. Furthermore, dynamics of block–block entanglement SL in the chain with even number spins is coincident with the dynamics of SN - L for D = 0. However, with the consideration of DM interactions, the evolution of SL will not be consistent with that of SN - L for the chain with odd number spins. In a given time interval, the maximal value of the generated nearest-neighbor concurrence [Formula: see text] will first decrease with the increase of chain's length, then oscillate with the increase of N. The maximal value and the minimal value of the oscillation becomes stable for a large N, and [Formula: see text] of the chain with odd spins is larger than that of the chain with even spins for a large N. The influence of DM interaction on the value of [Formula: see text] becomes unobvious with the increase of chain's length.

Magnitude thresholds and spatial footprints of damage from induced earthquakes

2020 ◽  
Vol 36 (4) ◽  
pp. 1995-2018 ◽  
Author(s):  
Bridger W Baird ◽  
Abbie B Liel ◽  
Robert E Chase
Keyword(s):  
United States ◽  
Ground Motions ◽  
Geographic Area ◽  
Earthquake Epicenter ◽  
Induced Earthquakes ◽  
Injection Wells ◽  
Building Models ◽  
Central United States ◽  
First Onset ◽  
Moderate Magnitude

The rise in the number of anthropogenic small- to moderate-magnitude earthquakes in the central United States raises questions about the damageability of the built environment in such events. This study examines the performance of modern light-frame wood buildings, including single, multifamily, and commercial constructions, in earthquakes with moment magnitudes of 3–6, using dynamic analysis of building models subjected to ground motions recorded in past induced events in North America. We focus on first onset of damage, for example, wallboard or wallpaper cracking, and nails popping out. The results show that earthquakes with magnitudes less than 4–4.25 are unlikely to cause damage to modern constructions. However, moderate-magnitude events can cause damage over a wide geographic area (more than 30 mi from the earthquake epicenter, or 40 or more miles from a wastewater injection well). These results can be used to suggest setback distances between injection wells and certain neighborhoods or facilities, and magnitude thresholds for post-earthquake inspections.

Exploring the Evolution and Source Properties of Injection-Induced Seismicity in Northern Oklahoma Using a Large-N Seismic Array

2020 ◽  
Author(s):  
Kilian B. Kemna ◽  
Alexander Wickham-Piotrowski ◽  
Andrés F. Peña-Castro ◽  
Elizabeth S. Cochran ◽  
Rebecca M. Harrington
Keyword(s):  
Radiation Pattern ◽  
Stress Drop ◽  
Induced Seismicity ◽  
Frequency Estimation ◽  
Vertical Component ◽  
Spectral Ratio ◽  
Focal Mechanisms ◽  
Seismic Survey ◽  
Corner Frequency ◽  
Large N

<p>The LArge-n Seismic Survey in Oklahoma (LASSO) array recorded local seismicity in 2016 in a region of active saltwater disposal. The month-long deployment of 1,833 vertical-component nodes had a nominal station spacing of 400 m and covered a 25 by 32 km<sup>2</sup> area. We estimate local event magnitudes and focal mechanisms of the induced seismicity using the vertical component waveforms from a catalog of 1375 earthquakes. Here we use the developed catalog to investigate the spatio-temporal evolution of seismicity and the source properties of the induced events.</p><p>The catalog is complete to a local magnitude of ~0.9, with a b-value of ~1.1. Focal mechanisms, which we determined using the HASH method, show a mix of strike-slip and normal faulting. The majority of the events are located at 1.5 – 5.0 km depth, where injection depths range from 0.1 – 2.0 km, and the basement contact is located at 1.5 – 2.5 km. Analysis of the coefficient of variation of interevent times suggests that the time evolution of seismicity is close to Poissonian, with minimal temporal clustering. We observe spatial clustering, with larger (M > 2) events occurring within dense clusters near the footprint of the array.</p><p>The dense station coverage of the array permits the exploration of variations in corner frequency and resulting stress drop estimates as a function of azimuth, i.e. radiation pattern. We calculate stress drops for the local catalog within 5 km of the array footprint from individual spectral and spectral ratio corner frequency values. Single spectra corner frequency estimates for events within the array footprint on individual nodes show evidence of variation related to radiation pattern, and vary as much as 100% from the mean for an individual event. Stress drop estimates from spectral ratio corner frequency estimations range between 10 – 100 MPa, show self-similar scaling, and fall within the typical range observed for intraplate (tectonic) earthquakes. Both single spectra and spectral ratio corner frequency estimates show a significant sample bias in the corner frequency estimation by using less than ~10 stations, and highlight the importance of azimuthal coverage for the stability of spectral estimates.</p>

A NOVEL SMALL-WORLD NETWORK MODEL: KEEPING CONNECTIVITY WITHOUT ADDING EDGES

2008 ◽  
Vol 22 (29) ◽  
pp. 5229-5234 ◽  
Author(s):  
XUHUA YANG ◽  
BO WANG ◽  
WANLIANG WANG ◽  
YOUXIAN SUN
Keyword(s):  
Network Model ◽  
Regular Ring ◽  
Nearest Neighbor ◽  
Small World ◽  
Clustering Coefficient ◽  
The Novel ◽  
Small World Network ◽  
Characteristic Path Length ◽  
Large N ◽  
Novel Model

Considering the problems of potentially generating a disconnected network in the WS small-world network model [Watts and Strogatz, Nature393, 440 (1998)] and of adding edges in the NW small-world network model [Newman and Watts, Phys. Lett. A263, 341 (1999)], we propose a novel small-world network model. First, generate a regular ring lattice of N vertices. Second, randomly rewire each edge of the lattice with probability p. During the random rewiring procedure, keep the edges between the two nearest neighbor vertices, namely, always keep a connected ring. This model need not add edges and can maintain connectivity of the network at all times in the random rewiring procedure. Simulation results show that the novel model has the typical small-world properties which are small characteristic path length and high clustering coefficient. For large N, the model is approximately equal to the WS model. For large N and small p, the model is approximately equal to the WS model or the NW model.

scholarly journals Geologic characterization of nonconformities using outcrop and whole-rock core analogues: hydrologic implications for injection-induced seismicity

2020 ◽  
Author(s):  
Elizabeth S. Petrie ◽  
Kelly K. Bradbury ◽  
Laura Cuccio ◽  
Kayla Smith ◽  
James P. Evans ◽  
...  
Keyword(s):  
Large Scale ◽  
Fluid Pressure ◽  
The United States ◽  
Crystalline Rock ◽  
Rock Properties ◽  
Induced Earthquakes ◽  
Injection Wells ◽  
Alteration Minerals ◽  
Reactive Fluids ◽  
Physical And Chemical

Abstract. The occurrence of induced earthquakes in crystalline rocks kilometres from deep wastewater injection wells poses questions about the influence nonconformity contacts have on the downward and lateral transmission of pore fluid pressure and poroelastic stresses. We hypothesize that structural and mineralogical heterogeneities at the sedimentary-crystalline rock nonconformity control the degree to which fluids, fluid pressure, and associated poroelastic stresses are transmitted over long distances across and along the nonconformity boundary. We examined the spatial distribution of physical and chemical heterogeneities in outcrops and whole-rock core samples of the great nonconformity in the midcontinent of the United States, capturing a range of tectonic settings and rock properties that we use to characterize the degree of historical fluid communication and the potential for future communication. We identify three end-member nonconformity types that represent a range of properties that will influence direct fluid pressure transmission and poroelastic responses far from the injection site. These nonconformity types vary depending on whether the contact is sharp and minimally altered, or if it is dominated by phyllosilicates or secondary non-phyllosilicate mineralization. We expect the rock properties associated with the presence or absence of secondary non-phyllosilicate mineralization and phyllosilicates to either allow or inhibit fractures to cross the nonconformity, thus impacting the permeability of the nonconformity zone. Our observations provide geologic constraints for modelling fluid migration and the associated pressure communication and poroelastic effects at large-scale disposal projects by providing relevant subsurface properties and much needed data regarding common alteration minerals that may interact readily with brines or reactive fluids.

scholarly journals Aftershock Rate Changes at Different Ocean Tide Heights

2020 ◽  
Vol 8 ◽  
Author(s):  
P. N. Shebalin ◽  
A. A. Baranov
Keyword(s):  
New Zealand ◽  
High Water ◽  
Earth Tides ◽  
Ocean Tide ◽  
Ocean Tides ◽  
Differential Probability ◽  
Main Shocks ◽  
Aftershock Sequences ◽  
Stress Changes ◽  
The Impact

The differential probability gain approach is used to estimate quantitatively the change in aftershock rate at various levels of ocean tides relative to the average rate model. An aftershock sequences are analyzed from two regions with high ocean tides, Kamchatka and New Zealand. The Omori-Utsu law is used to model the decay over time, hypothesizing an invariable spatial distribution. Ocean tide heights are considered rather than phases. A total of 16 sequences of M ≥6 aftershocks off Kamchatka and 15 sequences of M ≥6 aftershocks off New Zealand are examined. The heights of the ocean tides at various locations were modeled using FES 2004. Vertical stress changes due to ocean tides are here about 10–20 kPa, that is, at least several times greater than the effect due to Earth tides. An increase in aftershock rate is observed by more than two times at high water after main M ≥6 shocks in Kamchatka, with slightly less pronounced effect for the earthquakes of M = 7.8, December 15, 1971 and M = 7.8, December 5, 1997. For those two earthquakes, the maximum of the differential probability gain function is also observed at low water. For New Zealand, we also observed an increase in aftershock rate at high water after thrust type main shocks with M ≥6. After normal-faulting main shocks there was the tendency of the rate increasing at low water. For the aftershocks of the strike-slip main shocks we observed a less evident impact of the ocean tides on their rate. This suggests two main mechanisms of the impact of ocean tides on seismicity rate, an increase in pore pressure at high water, or a decrease in normal stress at low water, both resulting in a decrease of the effective friction in the fault zone.

Imaging the Shallow Structure of the Yucca Flat at the Source Physics Experiment Phase II Site with Horizontal-to-Vertical Spectral Ratio Inversion and a Large-N Seismic Array

2021 ◽  
Author(s):  
Richard Alfaro-Diaz ◽  
Ting Chen
Keyword(s):  
Shear Wave ◽  
Phase Ii ◽  
Volcanic Rocks ◽  
Spectral Ratio ◽  
Seismic Array ◽  
Shallow Subsurface ◽  
Large N ◽  
Physics Experiment ◽  
Shallow Structure ◽  
Source Physics

Abstract The Source Physics Experiment (SPE) is a series of chemical explosions at the Nevada National Security Site (NNSS) with the goal of understanding seismic-wave generation and propagation of underground explosions. To understand explosion source physics, accurate geophysical models of the SPE site are needed. Here, we utilize a large-N seismic array deployed at the SPE phase II site to generate a shallow subsurface model of shear-wave velocity. The deployment consists of 500 geophones and covers an area of, approximately, 2.5×2  km. The array is located in the Yucca Flat in the northeast corner of the NNSS, Nye County, Nevada. Using ambient-noise recordings throughout the large-N seismic array, we calculate horizontal-to-vertical spectral ratios (HVSRs) across the array. We obtain 2D seismic images of shear-wave velocities across the SPE phase II site for the shallow structure of the basin. The results clearly image two significant seismic impedance interfaces at ∼150–500 and ∼350–600  m depth. The shallower interface relates to the contrast between Quaternary alluvium and Tertiary volcanic rocks. The deeper interface relates to the contrast between Tertiary volcanic rocks and the Paleozoic bedrock. The 2D subsurface models support and extend previous understanding of the structure of the SPE phase II site. This study shows that the HVSR method in conjunction with a large-N seismic array is a quick and effective method for investigating shallow structures.

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