Automated coal seam detection using a modulated specific energy measure in a monitor-while-drilling context

Abstract

a b s t r a c tThis paper describes a novel measure called Modulated Specific Energy (SEM) which has been developed for the purpose of characterizing drilled material in open-pit coal mining. In Monitor-While-Drilling (MWD), the information available for coal detection are limited to a small set of drilling parameters that can be measured on a rotary drill rig. Despite this constraint, our analysis shows that MWD can still detect the top of the coal seam consistently without relying on geophysical data -such as bulk density and natural gamma -by using the SEM measure. The proposal utilizes a hypothesized link between a derived drill performance indicator (the rotation-to-thrust power ratio) and geomechanical properties of sedimentary rock strata (shear and compressive strengths) to increase the coal discriminative power of SEM relative to Teale's specific energy measure. Its efficacy is demonstrated using mutual information, a simple threshold strategy and an artificial neural network. The results show the SEM can detect the coal seam interface consistently with a greater margin for error, and overcome the problems of low specificity and high variability observed in existing MWD approaches. By reducing the detection uncertainty, the SEM is able to provide consistent feedback while drilling and eliminate trial-and-error. This makes coal mining processes more integrated and reliable, which in turn improves operational effectiveness and efficiency in coal recovery.

Coal top detection by conductively guided borehole radar wave imaging for open cut blast‐hole drilling

“…In a less favourable environment, a hybrid scheme that uses both guided BHR and measurement‐while‐drilling (MWD)/logging‐while‐drilling (LWD) (Mason and Hatherly ; Zhou and Dagnon ) for coal seam detection may have greater success in addressing excessive drill blast in the ‘stand‐off distance’ problem. Coal seam detection by MWD/LWD has been tried by Mason (), Leung and Scheding () and Bajram et al . (, ).…”

“…In a less favourable environment, a hybrid scheme that uses both guided BHR and measurementwhile-drilling (MWD)/logging-while-drilling (LWD) (Mason and Hatherly 1997;Zhou and Dagnon 2008) for coal seam detection may have greater success in addressing excessive drill blast in the 'stand-off distance' problem. Coal seam detection by MWD/LWD has been tried by Mason (2011), Leung and Scheding (2015) and Bajram et al (2015Bajram et al ( , 2017. For prospecting, combining geophysical and geomechanical measurements with adaptive sampling (model feedback) may offer an effective solution providing the site geology is relatively stable.…”

Preliminary Investigation into Measurement While Drilling as a Means to Characterize the Coalmine Roof

“…The method was first developed for the petroleum exploration industry [2]. The literature has examples of laboratory experiments, field trials, and the development of instruments to monitor while drilling [2][3][4][5][6][7][8][9][10][11][12]. Reference [6] provided a brief review of recent improvements on instrumented drills used in ground characterization and highlighted issues that are still lagging in using these instruments.…”

“…These tools have been developed by (a) Parvus Corporationn (Salt Lake City, UT, USA) Figure 3 illustrates the distinctive combinations of drilling parameters when different strata are encountered. Generally, the specific energy of drilling (mechanical work done by drill bit per unit volume of excavated material) [11] and, recently, the rotation to thrust power ratio [7] are used to measure the energy required to fracture rocks and classify rock types. Researchers have investigated the use of the specific energy of drilling as an indicator of the uniaxial compressive strength of the samples [5].…”

Drill monitoring results reveal geological conditions in blasthole drilling

“…A description of these results and a new MWD measure called Modulated Specific Energy (SEM) is introduced in Ref. 6. This approach is well suited for picking the changes in MWD performance when coal seams are encountered.…”