Jun Lu, Geomechanical engineer Daniel W.H. Su, Sr. Geomechanical engineer Greg J. Hasenfus, Sr. Geomechanical engineer Mark Van Dyke, Geologist Luke Stull, Geologist

Outline Introduction Objective Geology/Geologic Reconnaissance Hydro Frac Hole Locations and Frac Process Flac3D Models Longwall Visual Analysis (LVA) Monitoring Face Monitoring and Evaluation Conclusions

Introduction Panel 22 Panel 21 Panel 20

Introduction Longwall production footage per week Panel 21—SS fraced Panel 20—SS not fraced

Objective To compare and evaluate two hydraulic fractruing techniques which were employed to mitigate the impact of a massive sandstone channel on two successive longwall faces.

Geologic Reconnaissance Sandstone Intrusion Encountered During Development  In-Mine Core Drilling  Surface Core Drilling  Gas Well E-Logs  Stratascope Observations  In-Mine Mapping Sandstone Pittsburgh Main Bench Stopping

Geologic Reconnaissance Frac horizion 15ft above base of sandstone 5 Feet

Frac Hole Locations Panel 22 Hydraulic Fracture Hole Surface Corehole

Frac Process  Frac holes drilling  Perforations  Water fracing

Comparison of Panel 22 vs 21 Frac hole numbers: Panel 22: 3 Panel 21: 4 Water usage: Panel 22: 42,000 gallons/hole, 35 barrels/minute Panel 21: 14,000 gallons/hole, 25 barrels/minute Projected pancake fractures: Panel 22: 600 ft E-W, 400 ft N-S Panel 21: 250 ft E-W, 150 ft N-S

Panel 22 Panel 21

Outline Introduction Objective Geology/Geologic Reconnaissance Hydro Frac Hole Locations and Frac Process Flac3D Models Longwall Visual Analysis (LVA) Monitoring Face Monitoring and Evaluation Conclusions

Flac3D Model Without Frac Massive Sandstone Clayey Shale Longwall face Massive Sandstone Clayey Shale Longwall face Shear stress, psi With Frac Frac horizon 15 ft

Longwall Visual Analysis (LVA) LVA was installed to track the face pressure and cavity formation. Cavity Risk Index (CRI)

Mining Direction Correlation among the hydraulic fracturing hole locations, the LVA cavity formation predictions, and the observed face conditions in Panel 22. Face Monitoring and Evaluation

Panel 22 Panel 21 Mining Direction

Face Monitoring and Evaluation LVA: Time-Weighted Average Pressure (TWAP) Panel 22 Panel 21

Face Advance Rate at Panel 21 (11.2 ft/shift) Face Advance Rate at Panel 22 (15.6 ft/shift) Longwall Productivity

Rock Delay at Panel 21 (110 min./shift) Rock Delay at Panel 22 (27.5 min./shift) Longwall Rock Delay

Conclusions  Improved hydraulic fracturing technique  Successfully employed LVA software  Mitigated the impact of the massive sandstone channel  Increased productivity  Improved safety

Thanks! Questions?