7
31 Right (R26 to R29). The surface subsidence predicted
by the model is verified by the subsidence data provided
by the mine operator. The operator measured the surface
subsidence at the center of the 29 Right (R29) panel on
multiple survey locations by comparing the surveys per-
formed before R28 mined (07/2019) and after 29 Right
(R29) mined (04/2020). The maximum subsidence at the
panel center was measured as 1.11 ft, and the average of all
the survey measurements is 0.93 ft. The model predicted
1.03 ft subsidence at the center of the 29 Right Panel.
Figure 10 shows the shear failure zone predicted by the
model over the R30 and R31 panels. In this figure, shear
zones are overlayed on the plot that shows all the coal layers
on the overburden. All the Red-Green-Blue colored zones
represent the shear failure, and all the black colored layers
represent coal strata. Model predicted gas emission zone is
970 ft from the floor of the Pocahontas No. 3 seam.
DISCUSSION
Frack well evaluations on panels 31 Right and 1 South
showed inconsistent completions. The causes of this frack-
ing behavior are under evaluation, but some expected
results were not supported by the data. One of best frack-
ing completions at the Pocahontas No. 3 horizon on 31
Figure 9. The predicted vertical overburden displacement across the panels, after the mining of
panels 26 Right to 29 Right
Figure 10. The predicted gas emission zone
31 Right (R26 to R29). The surface subsidence predicted
by the model is verified by the subsidence data provided
by the mine operator. The operator measured the surface
subsidence at the center of the 29 Right (R29) panel on
multiple survey locations by comparing the surveys per-
formed before R28 mined (07/2019) and after 29 Right
(R29) mined (04/2020). The maximum subsidence at the
panel center was measured as 1.11 ft, and the average of all
the survey measurements is 0.93 ft. The model predicted
1.03 ft subsidence at the center of the 29 Right Panel.
Figure 10 shows the shear failure zone predicted by the
model over the R30 and R31 panels. In this figure, shear
zones are overlayed on the plot that shows all the coal layers
on the overburden. All the Red-Green-Blue colored zones
represent the shear failure, and all the black colored layers
represent coal strata. Model predicted gas emission zone is
970 ft from the floor of the Pocahontas No. 3 seam.
DISCUSSION
Frack well evaluations on panels 31 Right and 1 South
showed inconsistent completions. The causes of this frack-
ing behavior are under evaluation, but some expected
results were not supported by the data. One of best frack-
ing completions at the Pocahontas No. 3 horizon on 31
Figure 9. The predicted vertical overburden displacement across the panels, after the mining of
panels 26 Right to 29 Right
Figure 10. The predicted gas emission zone