Imaging mining hazards within coalbeds using prestack wave
equation migration of in-seam seismic survey data:
A feasibility study with synthetic data
Yanrong Hu, George A. McMechan
Center for Lithospheric Studies, The University of Texas at Dallas, PO Box 830688, Richardson, TX 75083-0688, USA
Received 16 June 2006; accepted 20 March 2007
Gas and water accumulations in old mine workings, voids and fault zones are threats to safety in coal mining. There are a variety of
measures that can be taken to extract fluids prior to, or during mining; therefore, the ability to locate geological structures and old
abandoned working and voids which may not have been mapped accurately are the key to overall success. However, current
techniques are of limited use because of either high cost or low resolution. We simulate and evaluate use of high-frequency seismic
data acquired in an in-seam geometry through the use of synthetic two-component elastic data for 2-D models. Elastic common-source
seismic data collected at the mining coalface contain body waves reflected at coalbed interfaces such as faults and old workings.
Reverse-time prestack elastic migration is used to image the interfaces. Numerical tests on synthetic data indicate that this approach is
expected to be effective to detect abandoned mining workings containing different fluids (such as water or gas/air) and faults.
However, the use of this approach is restricted to the nearest in-seam interface from the mine face. The three items that are new in this
paper are (1) the application of wave equation migration to in-seam data, (2) use of a multiplicative (data derived) mask to enhance the
migrated image, and (3) the demonstrated potential to distinguish fluids in mine voids from seismic data.
© 2007 Elsevier B.V. All rights reserved.
Keywords: Mining hazards; Seismic migration; Coal; Theoretical
Geologic hazards to mining (such as abandoned drill
holes, old workings, and faults) are potential threats to
the lives of coal miners and increase the cost of
underground mining. When coal mining breaks into
water or coalbed methane (CBM) accumulated in
natural or manmade voids, fluid outbursts or explosions
may occur; this happened to nine miners who were
trapped over 3 days in a flooding event at the Quecreek
Mine, Pennsylvania, in the United States, on July 24,
2002 (Gochioco, 2003). At least 31 coal miners were
killed after a massive CBM blast at the Krasnolimans-
kaya mine in Ukraine, on July 20, 2004 (Associated
Press, 2004). In 1981, the largest-ever outburst occurred
in Japan and expelled 4000 m
of coal and up to
of gas (Flores, 1998). Similar events have
occurred in Europe, Australia, and China (Flores, 1998).
Mine accidents produce reviews and recommenda-
tions for mining practise. For example, a commission
that was convened by the governor of Pennsylvania after
the Quecreek mine incident (Ramani et al., 2002)
Journal of Applied Geophysics 63 (2007) 24 – 34
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