1
25-001
A Comparison of Ground Permeability Changes Before, During,
and After Longwall Panel Mine-bys Under Deep and Shallow Cover
Marcia L. Harris
NIOSH, Pittsburgh, PA
Steven J. Schatzel
NIOSH, Pittsburgh, PA
Zoheir Khademian
NIOSH, Pittsburgh, PA
James Addis
NIOSH, Pittsburgh, PA
Y Zheng
NIOSH, Pittsburgh, PA
Charlie Matthews
NIOSH, Pittsburgh, PA
ABSTRACT
Shale gas wells can sometimes drill through coal reserves.
Hypothetically, the caving of the gob from longwall coal
mines may deform the shale gas well casing and potentially
result in a breach. NIOSH researchers studied the perme-
ability of the surrounding ground strata that may affect the
potential for an inflow of gas into an underground mine
environment. An overview and comparison of measured
permeability values under differing cover depths (147 m
and 353 m to the Pittsburgh coal seam) and mining cycle
phase will be presented and discussed in this report. The
findings highlight data-driven experimental evidence that
affect the interaction between gas wells extraction and
mining operations that may lead to potentially hazardous
environments.
INTRODUCTION
The Pennsylvania Department of Environmental Protection
(PADEP) has provided guidance on the placement of gas
wells near active longwall (LW) coal mining in Pennsylvania
through a technical report [1]. This guidance produced a
regulation which has played a very important role for coal
mine operators, gas well drillers and producers, and federal
and state regulatory agencies. Since the 1957 Joint Coal
and Gas Committee Gas Well Pillar Study [2] predate long-
wall mining, unconventional shale gas wells, and current
mining depths, there is a new set of safety and operational
challenges being faced by coal and gas well operators, regu-
lators, and permitting agencies. With the expectation of
1,000 gas wells that will be influenced by LW mining in
the Pennsylvania/West Virginia/Ohio tristate region in the
next 10 years, there is a gap in scientific information for gas
well stability in modern LW environments to ensure safe
practices are in place to maintain well casing stability for
wells in LW abutment pillars. The scientific findings sum-
marized in this publication are part of a research project by
the National Institute for Occupational Safety and Health
(NIOSH) which in turn will help miner safety and health
for LW mine operators and gas well producers for casing
stability in LW abutment pillars.
BACKGROUND
Within the past 15 years, unconventional shale gas wells
have been drilled through current and future coal reserves
in Pennsylvania, West Virginia, and Ohio. How this affects
the mechanical integrity of these wells is a concern when
mining occurs in and around these wells. The shale gas
wells penetrate the coal seams through abutment pillars
and the coal seams are subsequently mined by adjacent LW
panels. Overall, the study will provide scientific evidence
to the coal and shale gas industries on the impacts of LW
mining on the shale gas wells, what the potential deforma-
tion may be, and what stresses are imposed on the gas wells.
In 2012, the Pennsylvania Department of
Environmental Protection (PADEP) recognized the 1957
Pennsylvania Gas Well Pillar Regulation [2] was created
without current data from modern day LW mining and
called for research to revise the outdated regulation. Also,
the 1957 Pennsylvania Gas Well Pillar Regulation has been
widely used by the Mine Safety and Health Administration
25-001
A Comparison of Ground Permeability Changes Before, During,
and After Longwall Panel Mine-bys Under Deep and Shallow Cover
Marcia L. Harris
NIOSH, Pittsburgh, PA
Steven J. Schatzel
NIOSH, Pittsburgh, PA
Zoheir Khademian
NIOSH, Pittsburgh, PA
James Addis
NIOSH, Pittsburgh, PA
Y Zheng
NIOSH, Pittsburgh, PA
Charlie Matthews
NIOSH, Pittsburgh, PA
ABSTRACT
Shale gas wells can sometimes drill through coal reserves.
Hypothetically, the caving of the gob from longwall coal
mines may deform the shale gas well casing and potentially
result in a breach. NIOSH researchers studied the perme-
ability of the surrounding ground strata that may affect the
potential for an inflow of gas into an underground mine
environment. An overview and comparison of measured
permeability values under differing cover depths (147 m
and 353 m to the Pittsburgh coal seam) and mining cycle
phase will be presented and discussed in this report. The
findings highlight data-driven experimental evidence that
affect the interaction between gas wells extraction and
mining operations that may lead to potentially hazardous
environments.
INTRODUCTION
The Pennsylvania Department of Environmental Protection
(PADEP) has provided guidance on the placement of gas
wells near active longwall (LW) coal mining in Pennsylvania
through a technical report [1]. This guidance produced a
regulation which has played a very important role for coal
mine operators, gas well drillers and producers, and federal
and state regulatory agencies. Since the 1957 Joint Coal
and Gas Committee Gas Well Pillar Study [2] predate long-
wall mining, unconventional shale gas wells, and current
mining depths, there is a new set of safety and operational
challenges being faced by coal and gas well operators, regu-
lators, and permitting agencies. With the expectation of
1,000 gas wells that will be influenced by LW mining in
the Pennsylvania/West Virginia/Ohio tristate region in the
next 10 years, there is a gap in scientific information for gas
well stability in modern LW environments to ensure safe
practices are in place to maintain well casing stability for
wells in LW abutment pillars. The scientific findings sum-
marized in this publication are part of a research project by
the National Institute for Occupational Safety and Health
(NIOSH) which in turn will help miner safety and health
for LW mine operators and gas well producers for casing
stability in LW abutment pillars.
BACKGROUND
Within the past 15 years, unconventional shale gas wells
have been drilled through current and future coal reserves
in Pennsylvania, West Virginia, and Ohio. How this affects
the mechanical integrity of these wells is a concern when
mining occurs in and around these wells. The shale gas
wells penetrate the coal seams through abutment pillars
and the coal seams are subsequently mined by adjacent LW
panels. Overall, the study will provide scientific evidence
to the coal and shale gas industries on the impacts of LW
mining on the shale gas wells, what the potential deforma-
tion may be, and what stresses are imposed on the gas wells.
In 2012, the Pennsylvania Department of
Environmental Protection (PADEP) recognized the 1957
Pennsylvania Gas Well Pillar Regulation [2] was created
without current data from modern day LW mining and
called for research to revise the outdated regulation. Also,
the 1957 Pennsylvania Gas Well Pillar Regulation has been
widely used by the Mine Safety and Health Administration