Coal Age Magazine - For more than 100 years, Coal Age has been the magazine that readers can trust for guidance and insight on this important industry.
Issue link: https://coal.epubxp.com/i/640014
The Pittsburgh No. 8 seam: throughout h i s t o r y , o n e o f t h e l a r g e s t s o u r c e s o f domestic coal energy and also one of the worst regions for gas-related accidents. H o w e v e r , l a r g e l y a s a r e s u l t o f t h o s e events, it is also the heart of some of the world's best degasification resources, technology and research. Much of that is being used domestically and internation- ally to keep mines safe and allow miners to continue to go home each day. " C o a l i s w h a t w e ' v e g o t ; w e n e e d t o b u i l d o n w h a t w e ' v e g o t , " s a i d D r . Pramod Thakur, self-proclaimed father of coalbed methane degasification and four-decade industry veteran who is one of today's top sources for everything tied to gas ventilation. "[But] we need to degas mines, make sure mines are safe. You can't put a price on somebody's life." While the evolution of longwall mining has brought great strides in efficiency, p r o d u c t i o n a n d s a f e t y , a s t e c h n o l o g y has progressed, longwall panels across the nation have increased in dimension a n d a r e n o w w i d e r t h a n t h e y ' v e e v e r been. Panels that began at a modest 300 o r 4 0 0 f e e t a r e n o w o n a v e r a g e m o r e than 1,500 ft wide , and the Pittsburgh No. 8 seam is at the center of that growth with the nation's largest concentration of longwall faces. At the same time, the Pittsburgh No. 8 s e a m i s a l s o a m o n g t h e g a s s i e s t c o a l regions, which has left a perfect storm of sorts for longwall operators seeking to get the most from their mines. Coal gas' go-to expert — the Pennsyl- vania State University-educated Thakur developed many coal seam degasifica- tion techniques including in-mine hori- z o n t a l d r i l l i n g , v e r t i c a l g o b w e l l s a n d massive hydraulic fracking of coal seams — feels that, in this age of super-wide l o n g w a l l s , t h e r e i s s u c h a t h i n g a s a n optimum face width, ventilation layout and degasification plan. Importance of Degasification There is no doubt that knowledge of gas, and in this case the removal of it, is valu- able in many aspects. For mines, and long- walls especially, production at these highly profitable operations can increase exponentially and, in turn, lower overall costs for the mine tremendously. Over time, that equates to millions of dollars for a mining operation and, in turn, their par- ent company. Add in greater safety for the mine's workers, and it is a perfect storm of another, more positive kind. During June 2015, there were 47 active longwalls, more than a quarter of which were owned by Murray Energy Corp. (MEC); the Ohio-based miner itself pro- duces about 90 million tons annually. CONSOL Energy, former owner of some of those mines, had six remaining longwalls in its portfolio at the time. Arch Coal, Walter Energy and a handful of other min- ers rounded out the ownership circle. In terms of location, West Virginia has 13, half of which are MEC longwalls. Pennsylvania, also core territory for the Pittsburgh No. 8, has eight of those shear- ers cutting panels. Both states contain the deepest area of the seam, and as such, serve as home to a vast majority of these faces. Those deep seams bring with them high- er levels of gas. As seen in the above map, the deepest area averages 6 billion ft 3 per section (defined as a square mile, or 640 acres). Even the areas of outcrop as the seam begins to fade, gas averages 2 billion cf per section. According to Thakur, total gas in place is 7 trillion ft 3 across 6,000 square miles and 40 billion tons of coal. "It (the region) is quite gassy," he said. "Whenever the gas content goes up beyond 120 ft 3 /ton, you must degas, other- wise you are running a risk." The primary impetus for longwall min- ers pushing for greater panel dimensions is an understandable one and one that is both cost- and safety-driven: it is simply safer, more productive and less expensive to have fewer longwall moves. There is also more complete recovery of in-situ reserves with a super-wide longwall, and wider panels allow more time for gate development. However, there are also several disad- vantages to increasing panel dimensions, m i n e v e n t i l at i o n B Y D O N N A S C H M I D T , F I E L D E D I T O R The Benefits of Degasification When it comes to proper gas management and ventilation, a veteran industry expert answers the question: how wide is too wide for a longwall? 28 www.coalage.com February 2016 An illustration of the area encompassing the Pittsburgh No. 8 seam and its associated gas levels.