1
25-084
Study of Breached Gas Mitigation in An Underground Coal Mine
Using Network Modeling and Physical Model
Robert Kimutis
National Institute for Occupational Safety and
Health, Pittsburgh, PA, USA
Lihong Zhou
National Institute for Occupational Safety and
Health, Pittsburgh, PA, USA
Jim Addis
National Institute for Occupational Safety and
Health, Pittsburgh, PA, USA
Mark Mazzella
National Institute for Occupational Safety and
Health, Pittsburgh, PA, USA
ABSTRACT
Due to the surge in shale gas production, a substantial
number of unconventional shale gas wells have been drilled
across U.S. coal reserves. Gas breaches resulting from dam-
aged wells pose a considerable safety risk to miners. This
paper investigates how a ventilation system can effectively
manage breached gas through a network-based numerical
model and laboratory-scaled physical model. Several hypo-
thetical gas breach scenarios in a longwall area are simu-
lated, exploring factors influencing gas mitigation. The
study establishes correlations between breached gas inflow
and gas concentration at critical locations. The findings in
this study provide valuable insights for managing mine ven-
tilation systems and enhancing coal miner safety.
Keywords: Gas well ventilation network physical model
gas breach
INTRODUCTION
The advancement of horizontal drilling and hydraulic frac-
turing technologies has made it possible to commercially
develop unconventional gas reserves, particularly shale gas
reserves. Unconventional shale gas wells have been drilled
through current and future coal reserves in Pennsylvania,
West Virginia, Tennessee, and Ohio (Su, 2017). The integ-
rity of these wells becomes a concern to the mining com-
pany when mining occurs in proximity to the wells. The
shale gas wells penetrate the coal seam and an understand-
ing of the impacts to the mining operation from deformed
wells due to stresses is paramount to miners’ safety.
The National Institute for Occupational Safety and
Health (NIOSH) initiated research in 2012 provide
scientific evidence to the interaction of shale gas wells and
mining based upon modern mining technologies and prac-
tices. Previous regulations, such as the 1957 Pennsylvania
Gas Well Pillar Regulation formulated by the Pennsylvania
Department of Environmental Protection (PADEP), were
based upon data considering mining methods at that time,
which did not include modern-day longwall mining opera-
tions considerations (Commonwealth of Pennsylvania,
1957). NIOSH’s research has focused on evaluating the
stresses on well casings due to mining-induced ground
movements (Su, 2017 Su, et al., 2018, 2019a, 2019b,
2019c, 2021 Zhang, et al., 2020), monitoring permeabil-
ity changes during mining activities (Ajayi, et al., 2021
Watkins, et al., 2021 Harris, et al., 2023), and predict-
ing potential gas inflow to underground mines (Ajayi and
Schatzel, 2020 Ajayi, et al., 2022 Dougherty, et al., 2022).
Preventing gas breaches from gas wells into under-
ground mines is critical for ensuring mine safety. This
task requires an integrated approach that combines robust
engineering controls, strict regulatory oversight, and con-
tinuous monitoring. While best practices and preventive
measures have successfully prevented gas well breaches thus
far, the worst-case scenario remains a significant concern.
In such a case, the primary question is whether the existing
ventilation system can rapidly dilute and disperse any gas
that enters the mine to prevent any hazardous condition.
To address this concern, simulations using both
numerical and physical models are essential. These models
allow for the optimization of ventilation systems, assessing
their ability to handle potential gas breaches under vari-
ous controlled conditions. By simulating different breach
scenarios, researchers are attempting to identify weaknesses
25-084
Study of Breached Gas Mitigation in An Underground Coal Mine
Using Network Modeling and Physical Model
Robert Kimutis
National Institute for Occupational Safety and
Health, Pittsburgh, PA, USA
Lihong Zhou
National Institute for Occupational Safety and
Health, Pittsburgh, PA, USA
Jim Addis
National Institute for Occupational Safety and
Health, Pittsburgh, PA, USA
Mark Mazzella
National Institute for Occupational Safety and
Health, Pittsburgh, PA, USA
ABSTRACT
Due to the surge in shale gas production, a substantial
number of unconventional shale gas wells have been drilled
across U.S. coal reserves. Gas breaches resulting from dam-
aged wells pose a considerable safety risk to miners. This
paper investigates how a ventilation system can effectively
manage breached gas through a network-based numerical
model and laboratory-scaled physical model. Several hypo-
thetical gas breach scenarios in a longwall area are simu-
lated, exploring factors influencing gas mitigation. The
study establishes correlations between breached gas inflow
and gas concentration at critical locations. The findings in
this study provide valuable insights for managing mine ven-
tilation systems and enhancing coal miner safety.
Keywords: Gas well ventilation network physical model
gas breach
INTRODUCTION
The advancement of horizontal drilling and hydraulic frac-
turing technologies has made it possible to commercially
develop unconventional gas reserves, particularly shale gas
reserves. Unconventional shale gas wells have been drilled
through current and future coal reserves in Pennsylvania,
West Virginia, Tennessee, and Ohio (Su, 2017). The integ-
rity of these wells becomes a concern to the mining com-
pany when mining occurs in proximity to the wells. The
shale gas wells penetrate the coal seam and an understand-
ing of the impacts to the mining operation from deformed
wells due to stresses is paramount to miners’ safety.
The National Institute for Occupational Safety and
Health (NIOSH) initiated research in 2012 provide
scientific evidence to the interaction of shale gas wells and
mining based upon modern mining technologies and prac-
tices. Previous regulations, such as the 1957 Pennsylvania
Gas Well Pillar Regulation formulated by the Pennsylvania
Department of Environmental Protection (PADEP), were
based upon data considering mining methods at that time,
which did not include modern-day longwall mining opera-
tions considerations (Commonwealth of Pennsylvania,
1957). NIOSH’s research has focused on evaluating the
stresses on well casings due to mining-induced ground
movements (Su, 2017 Su, et al., 2018, 2019a, 2019b,
2019c, 2021 Zhang, et al., 2020), monitoring permeabil-
ity changes during mining activities (Ajayi, et al., 2021
Watkins, et al., 2021 Harris, et al., 2023), and predict-
ing potential gas inflow to underground mines (Ajayi and
Schatzel, 2020 Ajayi, et al., 2022 Dougherty, et al., 2022).
Preventing gas breaches from gas wells into under-
ground mines is critical for ensuring mine safety. This
task requires an integrated approach that combines robust
engineering controls, strict regulatory oversight, and con-
tinuous monitoring. While best practices and preventive
measures have successfully prevented gas well breaches thus
far, the worst-case scenario remains a significant concern.
In such a case, the primary question is whether the existing
ventilation system can rapidly dilute and disperse any gas
that enters the mine to prevent any hazardous condition.
To address this concern, simulations using both
numerical and physical models are essential. These models
allow for the optimization of ventilation systems, assessing
their ability to handle potential gas breaches under vari-
ous controlled conditions. By simulating different breach
scenarios, researchers are attempting to identify weaknesses