Gauge and Tube (also known as Trailing Hose or P-Q) Surveys have been widely used in underground mine ventilation for frictional pressure loss surveys and ventilation model calibrations for a very long time. They are one of the most basic types of underground ventilation measurement. However, there are many factors that have been contributing to and accelerating the decline of this type of survey and underground measurements more generally. In most cases, barometric pressure surveys are now the preferred method for validating ventilation circuits and models and can be completed more quickly, more cheaply, with fewer personnel and with less disruption to mine operations. In addition, the growing use of real-time instrumentation of the ventilation system combined with Big Data analysis techniques is reducing the amount of manual measurements and other data collection required. Artificial Intelligence is also likely to assist in the future with providing statistically reliable advice regarding the location, type and frequency of underground measurements, as well as answers to many other ventilation questions including validating ventilation models and providing site-specific advice on management of upset conditions such as fan or ventilation control failures or outages, fires or explosions. This paper discusses the factors behind these trends and identifies some of the advantages and disadvantages of both gauge and tube and barometric pressure surveys, as well as the broader potential use of Big Data and Artificial Intelligence to assist with decisions regarding underground measurements generally and assisting with other ventilation-related advice

Accurately measuring the airflow delivered by tunnel ventilation fans during site acceptance testing can be difficult due to the fan configuration and constrained sizes of adjoining plenums. Most axial flow tunnel ventilation fans are reversible with drive motors attached directly to the fan impeller. Obstructions created by the motor supports preclude performing pitot tube traverses in the fan section and the presence of transition ductwork and sound attenuators on each side of the fan dictate that airflow measurements be taken at the interface of fan equipment trains and adjoining plenums. Point air velocity measurements taken with an anemometer at one end of the fan equipment train are averaged to calculate the fan airflow. Limited floor space in tunnel ventilation buildings may result in narrow plenums adjacent to fan rooms that produce non-uniform flow with high velocities concentrated on one side, making the accuracy of the anemometer point traverses problematic. This paper presents the results of a study of optimum grid spacing of point anemometer measurements to yield more accurate field measurements using CFD modeling of sample fan room and plenum arrangements. Alternative grid spacings are evaluated against the modeled air velocity distribution to determine recommended spacing of measurement points.

Longwall-induced deformation could compromise the stability of shale gas wells positioned in the abutment pillars of current and future coal reserves. Consequently, gas from the casing(s) could flow towards the mine increasing the risk of explosive gas accumulation beyond the mandated limits. To assess the impact of this hypothetical scenario, the permeabilities of the surrounding strata is required to quantify potential gas flow to the mine. However, mining depth varies for different coal reserves could significantly impact permeability. Therefore, this study presents an analysis of longwall induced permeability under shallow, < 152 m (< 500 feet), and deep cover, >274 m (>900 feet) using measurements obtained from different study sites in Southwestern Pennsylvania along with discrete fracture network (DFN) modeling in 3DEC and Fracture Flow Code (FFC). The field study measured permeability changes for specific strata and the numerical model predicted the permeability for all the strata in the overburden. At the study site, the maximum permeability measured at the Uniontown horizon is 2.17×10-14 m2 (22 mD) and 2.42×10-13 m2 (246 mD) for deep and shallow cover site, respectively. These findings provide measure of comparing the potential risk of a hypothetical breach under a shallow and deep cover.

This paper summarizes the changes in permeability for two boreholes located above an abutment pillar in a longwall coal mine to characterize potential interaction between shale gas wells and the coal mine operations under deep cover. To determine the safety of the mine environment in case of a potential well breach, fracture network characteristics are needed to conduct a comprehensive hazard assessment. Permeability was measured using a falling-head slug test and calculated in accordance with the Hvorslev model during the mine-by of a longwall panel on one side of the pillar. The two boreholes had screened lengths at different depths to evaluate stratigraphic zones of interest above the active mining seam. The permeability at each borehole increased from pre-mining to post-mining and was highest while the face was close to and during mine-by of the test site.