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Time-Lapse Reflection Seismic Monitoring for Longwall Caving Assessment
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 80th EAGE Conference and Exhibition 2018, Jun 2018, Volume 2018, p.1 - 5
Abstract
Summary
As time goes on, coal mining gets deeper, mining conditions become more complex, longwall panels are becoming both wider and longer, and longwall retreat and development rates continue to increase. This trend requires a thorough understanding of the longwall caving process and associated strata fracture patterns in the overburden and the floor. This will assist design and planning of effective longwall support and goaf gas drainage systems, and allow assessment of the mining impact on surface water and groundwater systems. To achieve this, we have conducted time-lapse reflection seismic surveys at Zhuji Coal Mine in Huainan, China. Based on the characteristics of seismic events from these seismic surveys, it is demonstrated that time-lapse seismic surveying could be used for characterizing longwall caving effects. The prolonged reflections at both sides of the longwall panels match well with the numerical geomechanical modelling results in terms of the stress and permeability distributions of the overburden after mining, and provide a geophysical confirmation of the geotechnical conceptual model - the annual overlying zone for optimum gas drainage. In addition, the seismic data can also help to define the caving, fracture and subsidence zones of the overburden.
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