Assessing the Influence of Geology on Multiple-Seam Reserves Using a Boundary Element Model
CHEKAN, GREGORY J., and JEFFREY M. LISTAK, U.S. Bureau of Mines, Pittsburgh, PA
In the Eastern Coal Region, over 70 billion tons of minable reserves lie in a multiple seam configuration. Case study analysis has shown that the geology of the multiple-seam environment can adversely affect the stability of the workings. Overburden and interburden thickness and physical characteristics are the major geologic parameters influencing stress transfer and the potential for interactions between operations. Overburden is a major controlling factor because stress increases proportionally with depth. Interburdens composed of thick, monolithic strata having a high modulus of elasticity, such as sandstone, tend to dampen interactions, whereas interburdens composed of softer, lower modulus stratus, such as shale, tend to increase interactive effects. The layering or number of in er beds composing the interburden strata can also influence the potential for interaction because it serves to transfer stress to deeper horizons.
To further study the influence of geology in multiple-seam interactions, the Bureau of Mines combined case study information with a computer-aided design program called MULSIM/NL. MULSIM/NL is a boundary element method program, developed by the Bureau, for calculating stresses and displacements in tabular deposits. Analysis was performed on different room-and-pillar mining scenarios that are frequently encountered when developing multiple seams. Mine design parameters were kept constant while depth, interburden thickness, and interburden physical properties were varied to represent different geological influences. Geological trends and relationships developed from case studies in the Eastern Coal Region were used to evaluate and verify model results.
AAPG Search and Discovery Article #91005 © 1991 Eastern Section Meeting, Pittsburgh, Pennsylvania, September 8-10, 1991 (2009)