Scattering of guided SH and PSV modes by lateral disruptions in coal seams: A finite-element model study

M. W. Asten, L. A. Drake, S. A. Edwards

Research output: Chapter in Book/Report/Conference proceedingConference PaperOtherpeer-review

Abstract

In-seam seismic surveys are conducted to image coal seam structures both in reflection and transmission. It is important to understand the frequency-domain reflection and transmission characteristics of commonly occurring seam disruptions. Coal seams act as seismic waveguides carrying up to 6 modes of SH and PSV polarizations in the frequency range normally used. Fundamental symmetric modes of either polarization are predominantly excited by sources in midseam. We present the results of two-dimensional model calculations of mode scattering matrix elements observationally significant in in-seam seismic. The calculations are performed using a hybrid method: 2-D finite elements to model the central scattering region and 1-D finite elements (Rayleigh-Ritz method) to calculate the waveguide modes in regions of uninterrupted seam. Matching of solutions at the vertical boundaries of the scattering region is performed using the consistent boundary conditions of Lysmer and Wass (1972). We calculated the frequency-domain S matrix elements for incidence normal to strike in 124 models representing faults of varying throw and dip, dikes of varying thickness, hardness and dip, sills of varying hardness, stonerolls of varying height, and washouts terminating the seam with varying degrees of irregularity.

Original languageEnglish
Title of host publication1984 SEG Annual Meeting, SEG 1984
Subtitle of host publication1984 Society of Exploration Geophysicists Annual Meeting, SEG 1984; Atlanta; United States; 2 December 1984 through 6 December 1984
Pages597-600
Number of pages4
Publication statusPublished - 1 Jan 1984
Externally publishedYes
Event1984 Society of Exploration Geophysicists Annual Meeting, SEG 1984 - Atlanta, United States of America
Duration: 2 Dec 19846 Dec 1984

Conference

Conference1984 Society of Exploration Geophysicists Annual Meeting, SEG 1984
CountryUnited States of America
CityAtlanta
Period2/12/846/12/84

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