Three-dimensional time-lapse velocity tomography of an underground longwall panel

Luxbacher, Kray; Westman, Erik; Swanson, P. L.; Karfakis, Mario G.

doi:10.1016/j.ijrmms.2007.07.015

Cited by 97 publications

(52 citation statements)

References 20 publications

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“…Therefore, the time is calculated by integral of the inverse velocity (slowness), from the source to the receiver (Luxbacher et al, 2008b) as shown in Equations 1 to 3:…”

Section: Tomographymentioning

confidence: 99%

“…Although velocity, distance, and travel time in each individual voxel (or pixel) are unknown, but by the initial velocity model, distance and time along the raypath can be calculated. Of course, calculation of the distance in each voxel (or pixel) is not difficult, while the calculation of the velocity and the time are complicated (Luxbacher et al, 2008b). If the time, distance, and slowness for each voxel arranging into the matrix form, the velocity based on inverse theory is calculated as Equation 4:…”

Section: Tomographymentioning

confidence: 99%

“…The velocity and the frequency of the seismic events are averagely 3600 m/s and 30 Hz respectively. The number of event recorded per day is ranging from 100 to 800 events, with average daily 650 events (MSHA, 2010;Luxbacher et al, 2008a;Luxbacher et al, 2008b). In Figure 4 the location of mounted receivers on the surface, raypaths, and also longwall panel geometry are depicted.…”

Section: Case Studymentioning

confidence: 99%

“…Lack of control on the location, magnitude and other features of seismic events are the most important limitations. Because the high scattering and non-uniform of mining-induced microseismic events causes inadequate ray coverage in some area and thus in many cases, the quality of tomographic images to interpretations and stress inferring would not be appropriate (Luxbacher et al, 2008a;Luxbacher et al, 2008b). In this paper, firstly by using tomography with Simultaneous Iterative Reconstructive Technique (SIRT) inversion method, the location and velocity of seismic events are calculated.…”

Section: Introductionmentioning

confidence: 99%

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Passive seismic velocity tomography and geostatistical simulation on longwall mining panel / Tomografia pasywna pola prędkości i symulacje geostatystyczne w obrębie pola ścianowego

Hosseini¹,

Oraee²,

Shahriar³

et al. 2012

Archives of Mining Sciences

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Generally, the accurate determination of the stress in surrounding rock mass of underground mining area has an important role in stability and ground control. In this paper stress redistribution around the longwall face has been studied using passive seismic velocity tomography based on Simultaneous Iterative Reconstructive Technique (SIRT) and Sequential Gaussian Simulation (SGS). The mining-induced microseismic events are used as a passive source. Since such sources are used, the ray coverage is insufficient and in order to resolve this deficiency, the wave velocity is estimated in a denser network and by the SGS method. Consequently the three-dimensional images of wave velocity are created and sliced into the coal seam. To analyze the variations of stress around the panel during the study period, these images are interpreted. Results show that the state of stress redistribution around the longwall panel can be deduced from these velocity images. In addition, movements of the stressed zones, including front and side abutments and the goaf area, along the longwall face are evident. The applied approach illustrated in this paper can be used as a useful method to monitoring the stress changes around the longwall face continuously. This can have significant safety implications and contribute to improvements in operational productivity.Keywords: Longwall Mining, Passive Seismic Tomography, SIRT, SGS, Stress Redistribution Dokładne określenie naprężeń górotworu w warstwach otaczających wyrobiska podziemne ma podstawowe znaczenie dla stabilności i zabezpieczenia powierzchni. W artykule tym zbadano rozkłady naprężeń wokół przodka ścianowego przy wykorzystaniu tomografii pola prędkości, w oparciu o techniki rekonstrukcji przy równoczesnych iteracjach i sekwencyjnej symulacji Gaussa (SSG). Drobne wydarzenia mikrosejsmiczne wykorzystane zostały jako źródła bierne. Z uwagi na wykorzystanie takich źródeł, zasięg promieni jest niewystarczający, dlatego też prędkość fali określana jest przy użyciu gęstszej siatki Unauthenticated Download Date | 5/13/18 9:33 AM 140 i w oparciu o metody sekwencyjnej symulacji Gaussa. W rezultacie otrzymujemy trójwymiarowe obrazy prędkości fali, które następnie "narzucane" są warstwami na pokład węgla. Określenie naprężenia wokół pola w trakcie badania wymaga interpretacji tych obrazów. Wyniki wskazują, że rozkład stanu naprężenia wokół ściany można określić na podstawie obrazów prędkości. Ponadto, uwidaczniają się ruchy stref podlegających naprężeniom, w tym warstw sąsiadujących przednich i bocznych oraz obszaru samego wyrobiska wzdłuż przodka ściany. Zastosowane podejście może zostać wykorzystane jako skuteczna metoda bieżącego monitorowania zmian naprężeń w rejonie ściany. Ma to poważne znaczenie z punktu widzenia bezpieczeństwa pracy, a co za tym idzie przyczynia się do podniesienia wydobycia.Słowa kluczowe: wybieranie ścianowe, tomografia pola prędkości, metody rekonstrukcji przy równo-czesnych iteracjach, symulacja sekwencyjna Gaussa, rozkład naprężeń

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“…Therefore, the time is calculated by integral of the inverse velocity (slowness), from the source to the receiver (Luxbacher et al, 2008b) as shown in Equations 1 to 3:…”

Section: Tomographymentioning

confidence: 99%

Section: Tomographymentioning

confidence: 99%

Section: Case Studymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Passive seismic velocity tomography and geostatistical simulation on longwall mining panel / Tomografia pasywna pola prędkości i symulacje geostatystyczne w obrębie pola ścianowego

Hosseini¹,

Oraee²,

Shahriar³

et al. 2012

Archives of Mining Sciences

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“…Tomography techniques are advantageous for imaging the integrity of the caprock in the CCS projects. Velocity tomography uses waves to model entities based on the arrival time of waves (Westman et al 2001, Westman 2004, Luxbacher et al 2008. Seismic tomography is a data inference technique that exploits information contained in seismic records to constrain 2D or 3D models of the Earth's interior.…”

Section: Introductionmentioning

confidence: 99%

CO2 Sequestration Safety Monitoring by using Seismic Imaging and Double Difference Tomography

Sun

Westman

Fahrman

et al. 2017

IJGE

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Shale gas has become an increasingly important clean energy, which has been explored worldwide in recent decades. In the shale gas production, supercritical CO2 acts as a fracturing fluid. For preventing any kinds of leakage of the injected supercritical CO2, it is essential to monitor the stability of its storage hundreds of kilometres beneath the Earth's surface. Seismic tomography is an imaging technique that uses induced seismic waves to create three dimensional images of the subsurface. It is an effective monitoring method to evaluate the caprock integrity in the CO2 sequestration storage (CCS). In this experimental research, a simulated uniaxial compressive load was applied on a granite sample to analyze the stress redistribution for long-term in-situ caprock integrity during CO2 injection. The induced seismic waves were recorded, and seismic events were located according to the Geiger algorithm. The frequency of seismic events correlates with the caprock failure evolution. Based on the frequency of seismic events and the failure process, the seismic data is divided into four regimes to examine the failure evolution. Finally, the double difference tomography (TomoDD) algorithm using arrival time was adopted to recalculate to modify the locations of seismic events and velocity structure in each regime. The results indicate that the passive seismic system can map the caprock stress distribution and allow for imaging of the caprock integrity. TomoDD exhibits sound improvements to relocate seismic events both in relative and absolute locations as well as to characterize the local velocity structure. The study further reveals that seismic monitoring along with TomoDD could evaluate the caprock failure accurately in the CCS.

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Case study on the mining‐induced stress evolution of an extra‐thick coal seam under hard roof conditions

Xie

Gao

et al. 2020

Energy Science & Engineering

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A strong mining disturbance may cause the superposition of local stresses and serious disasters such as crushed supports and severely destroyed roadways. To study the distribution law of mining‐induced stress under hard roof conditions, an advance abutment pressure distribution model was developed. By monitoring the support pressure, a novel method of reckoning intensive factors was proposed, and then, the pressure distribution characteristics were obtained. An innovative in situ test of the mining‐induced stress increment was performed. At the Tongxin coal mine, the field monitoring of no. 8309 working face revealed the following. (a) The peak position of the fully mechanized working face with a hard roof was 5.9 m away from the mining face in which the average intensive factor K was 1.48. The pressure of the single props developed could be roughly divided into the fluctuation, slow increase, and stable stages. (b) A theoretical model of the stress evolution of the working face was proposed. Using an in situ uniaxial compression test, a law governing the variation of the advance abutment pressure was developed. The peak strength was reported to be 36 MPa, which is consistent with the advance prop pressure. (c) Mining‐induced stress violently fluctuated during the process of top coal caving; the K values in the supports in the middle of the working face and their rates of growth were apparently higher than those in the end supports. A Gaussian distribution of K was established for this phenomenon. The results obtained provide first‐hand data for safe and efficient mining under similar geological conditions.

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Three-dimensional time-lapse velocity tomography of an underground longwall panel

Cited by 97 publications

References 20 publications

Passive seismic velocity tomography and geostatistical simulation on longwall mining panel / Tomografia pasywna pola prędkości i symulacje geostatystyczne w obrębie pola ścianowego

Passive seismic velocity tomography and geostatistical simulation on longwall mining panel / Tomografia pasywna pola prędkości i symulacje geostatystyczne w obrębie pola ścianowego

CO2 Sequestration Safety Monitoring by using Seismic Imaging and Double Difference Tomography

Case study on the mining‐induced stress evolution of an extra‐thick coal seam under hard roof conditions

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