Daniel W.H. Su, Sr. geomechanical engineer Greg J. Hasenfus, Sr. geomechanical engineer Luke Stull, geologist Jun Lu, geomechanical engineer Mark Van Dyke, geologist Stephen Morgan, geologist Paul Kelley, mine engineer Don Teter, project engineer 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 Introduction Sandstone Intrusion Encountered During Development Introduction Sandstone Intrusion Encountered During Development Base of Sandstone Channel Introduction Massive sandstone pot-outs in front of shields Increased risk to personnel Delayed Production Longwall production footage per week 371 338 230 106 24 306 Delayed caving behind shield supports 344 F20 Longwall Panel Problems Objective To evaluate the effectiveness of the hydraulic fracturing program and the validity of Longwall Visual Analysis (LVA) software to mitigate the impact of a 1, 000-foot (305-meter) wide massive sandstone channel on a 1,500-ft-wide (457-meter-wide) longwall face. Geologic Reconnaissance In-Mine Core Drilling Stratascope Observations In-Mine Mapping Primary Stress Orientation Rock Lab Testing Average Axial Compressive Strength 8283 psi Geologic Reconnaissance INBY Base of Sandstone WALL #27 WALL #33 OUTBY Trough of Sandstone Channel at Wall # 29 Vertical Scale Pittsburgh Seam 5 Feet Drawslate Frac Hole Locations and Frac Stage Horizons Frac Process Perforations were shot into the casing at the targeted horizons to prefracture the sandstone. The estimated shot penetration into the borehole surface was about 26 to 30 inches (0.66 to 0.76 meter). Frac Process Water fracing was employed Frac Process Fracing result Initial break Shut-in 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 3.10 Job Title: F-21 Sandstone Frac-Before Flac3D Model ©2006 Itasca Consulting Group, Inc. View Title: Step 15221 Model Perspective 14:55:06 Wed Jul 18 2012 Center: Rotation: Without X: 1.585e+000 X: 0.000 Y: 2.107e+002 Y: 0.000 Job Title: F-21 Sandstone Frac-Before FLAC3D Z: 3.10 Z: 8.023e+000 90.000 View Title: ©2006 Itasca Consulting Group, Inc. Dist: 1.361e+003 Mag.: 18.2 Step 15221 Model Perspective Ang.: 22.500 16:37:57 Thu Jul 26 2012 Rotation: X: 0.000 Magfac = 1.000e+000 Y: 2.138e+002 Y: 0.000 stress, Z:Shear 1.400e+001 Z: 90.000psi Live mech zones shown Dist: 1.361e+003 Mag.: Gradient Calculation 18.2 Ang.: 22.500 3.0000e+003 to 3.5000e+003 3.5000e+003 to 4.0000e+003 4.0000e+003 to 4.3785e+003 Interval = 5.0e+002 Itasca Consulting Group, Inc. Minneapolis, MN USA Itasca Consulting Group, Inc. Minneapolis, MN USA FLAC3D 3.10 ©2006 Itasca Consulting Group, Inc. Frac horizon Job Title: F-21 Sandstone Frac-After View Title: Step 11503 Model Perspective 16:38:18 Thu Jul 26 2012 Center: X: 2.000e+000 Y: 3.860e+002 Z: 1.400e+001 Dist: 1.361e+003 Center: Zone Extra 1 X: 2.000e+000 1.9448e+002 to 5.0000e+002 5.0000e+002 to 1.0000e+003 Zone Extra 1 to 1.5000e+003 1.0000e+003 Magfac = 1.000e+000 1.5000e+003 to 2.0000e+003 Live mech zones shown 2.0000e+003 to 2.5000e+003 Gradient Calculation 2.5000e+003 to 3.0000e+003 1.4037e+002 to 5.0000e+002 3.0000e+003 to 3.5000e+003 5.0000e+002 to 1.0000e+003 1.0000e+003 to 1.5000e+003 3.5000e+003 to 4.0000e+003 1.5000e+003 to 2.0000e+003 4.0000e+003 to 4.3785e+003 2.0000e+003 to 2.5000e+003 Interval = 5.0e+002 2.5000e+003 to 3.0000e+003 With Frac Frac Rotation: X: 0.000 Y: 0.000 Z: 90.000 Mag.: 18.2 Ang.: 22.500 15 ft Zone Extra 1 Massive Sandstone Clayey Shale Magfac = 1.000e+000 Live mech zones shown Gradient Calculation 1.9448e+002 to 5.0000e+002 5.0000e+002 to 1.0000e+003 1.0000e+003 to 1.5000e+003 1.5000e+003 to 2.0000e+003 2.0000e+003 to 2.5000e+003 2.5000e+003 to 3.0000e+003 3.0000e+003 to 3.5000e+003 3.5000e+003 to 4.0000e+003 4.0000e+003 to 4.3785e+003 Interval = 5.0e+002 Massive Sandstone Clayey Shale Longwall face Longwall face Itasca Consulting Group, Inc. Minneapolis, MN USA Longwall Visual Analysis (LVA) LVA was installed to track the face pressure and cavity formation index. Cavity Risk Index (CRI) Face Monitoring and Evaluation To evaluate the effectiveness of the hydraulic fracturing program and the validity of LVA software, daily face monitoring over a 4-week period was conducted. Based on the collected information, the correlations among the observed face conditions, the hydro frac hole locations and the LVA cavity formation prediction were analyzed. Underground Observation Hydraulic Fracturing Longwall Visual Analysis Ming Direction Dec. 20, 2011 Face Monitoring and Evaluation Face Monitoring and Evaluation Face Monitoring and Evaluation 323 194 115 142 232 124 F21—SS fraced 240 338 230 106 24 306 344 Longwall production F20—SS not fraced footage per week Conclusions Successful application of hydraulic fracturing technique. Successful application of LVA software. Improve safety and increase productivity. Thanks! Questions?