Analysis of a Collapse in Deep Tunnel Based on Microseismic Monitoring

2012 ◽  
Vol 256-259 ◽  
pp. 1181-1186 ◽  
Author(s):  
Guang Liang Feng ◽  
Xia Ting Feng ◽  
Zhou Neng Zhao ◽  
Guo Feng Liu ◽  
Ya Xun Xiao
Keyword(s):  
Average Distance ◽  
Moment Tensor ◽  
Case Analysis ◽  
Microseismic Monitoring ◽  
Typical Case ◽  
Economic Losses ◽  
Failure Evolution ◽  
Mixed Fracture ◽  
The Rich ◽  
Microseismic Event

Tunnel collapse causes serious casualties and economic losses. One typical case analysis of a collapse in deep-buried tunnel based on microseismic monitoring is presented. The results show that the number of microseismic event keeps increasing and the distribution of microseismic events becomes concentrated in space domain gradually during collapse nucleation process. And average distance squared decreases gradually during the imminent period time just before the collapse. The failure evolution mechanism of the collapse is analyzed by moment tensor method. It is noted that the failure mechanism between this kind of collapse and immediate strain-structure rockburst is similar. However, the proportion of shear and mixed fracture for collapse is higher than immediate strain-structure rockburst. It due to the rich structure planes in collapse zone.

Simultaneous microseismic event localization and source mechanism determination

Geophysics ◽  
2015 ◽  
Vol 80 (1) ◽  
pp. KS1-KS9 ◽  
Author(s):  
Oksana Zhebel ◽  
Leo Eisner
Keyword(s):  
Oil And Gas ◽  
Signal To Noise Ratio ◽  
Moment Tensor ◽  
Microseismic Monitoring ◽  
Primary Objective ◽  
Gas Production ◽  
Source Mechanism ◽  
Seismic Events ◽  
Near Surface ◽  
Microseismic Event

Microseismic monitoring has become a tool of choice for the development and optimization of oil and gas production from unconventional reservoirs. The primary objective of (micro) seismic monitoring includes localization of (micro) seismic events and characterization of their source mechanisms. Most seismic events are of a nonexplosive nature, and thus, there are waveform (polarity) differences among receivers. Specifically, double-couple sources represented a challenge for migration-based localization techniques. We developed and applied a new migration-type location technique combined with source mechanism inversion that allowed for constructive interference of signal in seismic waveforms. The procedure included constructing image functions by stacking the amplitudes with compensated polarity changes. The compensation weights were calculated by using moment tensor inversion. This method did not require any picking of arrivals at individual receivers, but it required receivers to be distributed in multiple azimuths and offsets. This made the technique suitable for surface or near-surface monitoring, in which a low signal-to-noise ratio (S/N) can be overcome by stacking. Furthermore, the advantage of this technique was that in addition to the position in time and space, we also determined the source mechanism. We determined with numerical tests that the proposed technique can be used for detection and location of events with S/Ns as low as 0.05 at individual (prestacked) receivers. Furthermore, we found that other source mechanism parameters such as magnitude, volumetric, or shear components of the source mechanism were not suitable for the location. Finally, we applied the proposed technique to a microseismic event of moment magnitude [Formula: see text] induced during the hydraulic fracturing treatment of a gas shale reservoir in North America.

Seismic Moment Tensor Inversion of an Induced Microseismic Event, Offshore Norway: An Insight into the Possible Cause of Wellbore Liner Failure during a Drilling Operation

2021 ◽  
Vol 92 (6) ◽  
pp. 3460-3470
Author(s):  
Zoya Zarifi ◽  
Fredrik Hansteen ◽  
Florian Schopper
Keyword(s):  
Seismic Moment ◽  
Moment Tensor ◽  
Moment Tensor Inversion ◽  
Seismic Moment Tensor ◽  
Isotropic Component ◽  
High Pump ◽  
Dc Component ◽  
Pump Pressure ◽  
Microseismic Event ◽  
Possible Cause

Abstract A microseismic event with Mw∼0.8 was recorded at the Grane oilfield, offshore Norway, in June 2015. This event is believed to be associated with a failure of the wellbore liner in well 25/11-G-8 A. The failure mechanism has been difficult to explain from drilling parameters and operational logs alone. In this study, we analyzed the detected microseismic event to shed light on the possible cause of this event. We inverted for the seismic moment tensor, analyzed the S/P amplitude ratio and radiation pattern of seismic waves, and then correlated the microseismic data with the drilling reports. The inverted seismic moment indicates a shear-tensile (dislocation) event with a strong positive isotropic component (67% of total energy) accompanied by a positive compensated linear vector dipole (CLVD) and a reverse double-couple (DC) component. Drilling logs show a strong correlation between high pump pressure and the occurrence of several microseismic events during the drilling of the well. The strongest microseismic event (Mw∼0.8) occurred during peak pump pressure of 277 bar. The application of high pump pressure was associated with an attempt to release the liner hanger running tool (RT) in the well, which had been obstructed. Improper setting of the liner hanger could have caused the forces from the RT release to be transferred to the liner and might have resulted in ripping and parting of the pipe. The possible direct impact of the ripped liner with the formation or the likely sudden hydraulic pressure exposure to the formation caused by the liner ripping may explain the estimated isotropic component in the moment tensor inversion in the well. This impact can promote slip along the pre-existing fractures (the DC component). The presence of gas in the formation or the funneled fluid to the formation caused by the liner ripping may explain the CLVD component.

Typical case analysis of overload damage fault in distribution station area

2020 ◽  
Author(s):  
Dai WAN ◽  
Weihua ZHOU ◽  
Fei QI ◽  
Hengyi ZHOU ◽  
Miao ZHAO ◽  
...  
Keyword(s):  
Case Analysis ◽  
Typical Case ◽  
Distribution Station

scholarly journals Insect Pest Complex of Wheat Crop

2021 ◽  
Author(s):  
Mirza Abdul Qayyum ◽  
Shafqat Saeed ◽  
Unsar Naeem-Ullah ◽  
Amar Matloob ◽  
Muhammad Wajid ◽  
...  
Keyword(s):  
Proper Time ◽  
Abiotic Factors ◽  
Insect Pest ◽  
Management Strategies ◽  
Triticum Aestivum L ◽  
Climatic Conditions ◽  
Economic Losses ◽  
Taxonomic Rank ◽  
Reproductive Part ◽  
The Rich

Wheat Triticum aestivum L. is grown on broad range of climatic conditions because of edible grains, cereal crop and stable food of about 2 Billion peoples worldwide. Additionally, it is the rich source of carbohydrates (55–60%), vegetable proteins and contributed 50–60% daily dietary requirement in Pakistan. Globally, wheat crops is grown over 90% area of total cultivated area; facing devastating biotic and abiotic factors. The estimated economic losses in wheat quantity and quality are about 4 thousands per tonne per year including physical crop losses and handling. Economic losses of about 80–90 million USD in Pakistan are recorded due to inadequate production and handling losses. Wheat agro-ecosystem of the world colonizes many herbivore insects which are abundant and causing significant losses. The feeding style of the insects made them dispersive from one habitat to another imposing significant crop loss. Areas of maximum wheat production are encountered with either insect which chew the vegetative as well as reproductive part or stem and root feeders. This chapter provides the pest’s taxonomic rank, distribution across the globe, biology and damage of chewing and sucking insect pest of wheat. It is very important to study biology of the pest in accordance with crop cycle to forecast which insect stage is economically important, what the proper time to manage pest is and what type of control is necessary to manage crop pest. The chapter will provide management strategies well suited to pest stage and environment.

scholarly journals Typical case analysis of deep tunnel drainage system in urban area

2017 ◽  
Vol 62 (27) ◽  
pp. 3269-3276 ◽  
Author(s):  
JiaHong LIU ◽  
Lin XIA ◽  
Hao WANG ◽  
WeiWei SHAO ◽  
XiangYi DING
Keyword(s):  
Urban Area ◽  
Drainage System ◽  
Case Analysis ◽  
Typical Case ◽  
Deep Tunnel

On the importance of benchmarking algorithms under realistic noise conditions

2020 ◽  
Vol 221 (1) ◽  
pp. 504-520
Author(s):  
Claire Birnie ◽  
Kit Chambers ◽  
Doug Angus ◽  
Anna L Stork
Keyword(s):  
Event Detection ◽  
Gaussian Noise ◽  
Moment Tensor ◽  
Synthetic Data ◽  
Data Sets ◽  
Signal To Noise ◽  
Noise Data ◽  
Recorded Data ◽  
Imaging Algorithms ◽  
Microseismic Event

SUMMARY Testing with synthetic data sets is a vital stage in an algorithm’s development for benchmarking the algorithm’s performance. A common addition to synthetic data sets is White, Gaussian Noise (WGN) which is used to mimic noise that would be present in recorded data sets. The first section of this paper focuses on comparing the effects of WGN and realistic modelled noise on standard microseismic event detection and imaging algorithms using synthetic data sets with recorded noise as a benchmark. The data sets with WGN underperform on the trace-by-trace algorithm while overperforming on algorithms utilizing the full array. Throughout, the data sets with realistic modelled noise perform near identically to the recorded noise data sets. The study concludes by testing an algorithm that simultaneously solves for the source location and moment tensor of a microseismic event. Not only does the algorithm fail to perform at the signal-to-noise ratios indicated by the WGN results but the results with realistic modelled noise highlight pitfalls of the algorithm not previously identified. The misleading results from the WGN data sets highlight the need to test algorithms under realistic noise conditions to gain an understanding of the conditions under which an algorithm can perform and to minimize the risk of misinterpretation of the results.

scholarly journals Adaptive moment-tensor joint inversion of clustered microseismic events for monitoring geological carbon storage

2019 ◽  
Vol 219 (1) ◽  
pp. 80-93
Author(s):  
Yu Chen ◽  
Lianjie Huang
Keyword(s):  
Carbon Storage ◽  
Oil Recovery ◽  
Joint Inversion ◽  
Moment Tensor ◽  
Crack Opening ◽  
Cost Effective ◽  
Microseismic Monitoring ◽  
Moment Tensor Inversion ◽  
Inversion Method ◽  
Microseismic Events

SUMMARY Moment-tensor inversion of induced microseismic events can provide valuable information for tracking CO2 plumes at geological carbon storage sites, and study the physical mechanism of induced microseismicity. Accurate moment-tensor inversion requires a wide-azimuthal coverage of geophones. Cost-effective microseismic monitoring for geological carbon storage often uses only one geophone array within a borehole, leading to a large uncertainty in moment-tensor inversion. We develop a new adaptive moment-tensor joint inversion method to reduce the inversion uncertainty, when using limited but typical geophone receiver geometries. We first jointly invert a number of clustered microseismic events using a uniform focal mechanism to minimize the waveform misfit between observed and predicted P and S waveforms. We then invert the moment tensor for each event within a limited searching range around the joint inversion result. We apply our adaptive joint inversion method to microseismic data acquired using a single borehole geophone array at the CO2-Enhanced Oil Recovery field at Aneth, Utah. We demonstrate that our inversion method is capable of reducing the inversion uncertainty caused by the limited azimuthal coverage of geophones. Our inverted strikes of focal mechanisms of microseismic events are consistent with the event spatial distribution in subparallel pre-existing fractures or geological imperfections. The large values up to 40 per cent of the CLVD components might indicate crack opening induced by CO2/wastewater injection or rupture complexity.

The ML = 6.8 25 October 2018 Earthquake Zakynthos Island (Ionian Sea) and the evolution of the aftershock sequence one year later

2020 ◽  
Author(s):  
Alexandra Moshou ◽  
Antonios Konstantaras ◽  
Panagiotis Argyrakis ◽  
Nikolaos Sagias
Keyword(s):  
Moment Tensor ◽  
Focal Depth ◽  
Plate Boundary ◽  
Boundary Region ◽  
Aftershock Sequence ◽  
Ionian Sea ◽  
13Th Century ◽  
Hellenic Arc ◽  
The Rich ◽  
The Moment

<p>The area of Zakynthos (Ionian Island) is located at a complex plate boundary region where two tectonic plates (Africa-Nubia and Eurasia) converge, thus forming the western Hellenic Arc. On the midnight of 26<sup>th</sup> October (M<sub>L</sub> = 6.6, 22:54:49 UTC) a very strong earthquake has struck at the eastern part of Zakynthos Island (Ionian Sea, Western Greece). Epicentral coordinates of the earthquake was determined as 37.3410° N, 20.5123° E and a focal depth at 10 km, according to the manual solution of National Observatory of Athens</p><p>(http://bbnet.gein.noa.gr/alerts_manual/2018/10/evman181025225449_info.html).</p><p>This earthquake was strongly felt at the biggest shock was felt as far afield as Naples in western Italy, and in Albania, Libya, and the capital Athens. Nobody was injured by these events but there was significant damage to the local port and a 13th Century island monastery south of Zakynthos.</p><p>A few minutes later (23:09:20, UTC) a second intermediate earthquake with magnitude M<sub>L</sub>=5.1 was followed the first event. The M5+ events of 25 October 2019, as well as the rich aftershock sequence of 10.000+ events with magnitudes 1.0<ML<4.9 of the 12 following months have been relocated using the double – difference algorithm HYPODD.</p><p>For the aftershocks with 3.7<M<sub>L</sub><6.6 we applied the moment tensor inversion to determine the activation of the faulting type, the Seismic Moment (M<sub>0</sub>) and the Moment Magnitude (M<sub>w</sub>). For this purpose, 3–component broadband seismological data from the Hellenic Unified Seismological Network (HUSN) at epicentral distances less than 3˚ were selected and analyzed. The preparation of the data, includes the deconvolution of instrument response, following the velocity was integrated to displacement and finally the horizontal components rotated to radial and transverse. All the focal mechanisms were compared with those from other institutes and they are in agreement. The second part of this study refers to the calculation of the stress tensor using the STRESSINVERSE package by Václav Vavryčuk. The final part of this study includes an extensive kinematic analysis of geodetic data from local GNSS permanent station to further examine the dynamic displacement.</p><p>References:</p><ol><li>Athanassios Ganas, Pierre Briole, George Bozionelos, Panagiotis Elias, Sotiris Valkaniotis, Varvara Tsironi, Alexandra Moshou and Nikoletta Andritsou, 2019. The October 25, 2018 M6.7 Zakynthos earthquake sequence (Ionian Sea, Greece): fault modeling from seismic and GNSS data and implications for seismic strain release along the western Hellenic Arc, 15th, Sp. Pub. 7, Ext. Abs. GSG2019 – 324</li> <li>Konstantaras A.J. Classification of distinct seismic regions and regional temporal modelling of seismicity in the vicinity of the Hellenic seismic arc. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing. 6 (4), 1857-1863, 2012.</li> <li>Gerassimos A. Papadopoulos, Vassilios K. Karastathis, Ioannis Koukouvelas, Maria Sachpazi, Ioannis Baskoutas, Gerassimos Chouliaras, Apostolos Agalos, Eleni Daskalaki, George Minadakis, Alexandra Moshou, Aggelos Mouzakiotis, Katerina Orfanogiannaki, Antonia Papageorgiou, Dimitrios Spanos, Ioanna Triantafyllou. The Cephalonia, Ionian Sea (Greece), sequence of strong earthquakes of January – February 2014: A first report, Research in Geophysics 2014; 4:5441</li> </ol>

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