daniel w.h. su, sr. geomechanical engineer greg j. hasenfus, sr. geomechanical engineer luke stull,...
TRANSCRIPT
Impact of a Massive Sandstone Channel on a 1500-Foot (457-Meter) Wide Longwall
Face – Mitigation and EvaluationDaniel W.H. Su, Sr. geomechanical engineer
Greg J. Hasenfus, Sr. geomechanical engineerLuke Stull, geologist
Jun Lu, geomechanical engineerMark Van Dyke, geologist
Stephen Morgan, geologistPaul Kelley, mine engineerDon 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
F20 Longwall Panel Problems
Delayed caving behind shield supports
Massive sandstone pot-outs in front of shields
Increased risk to personnelDelayed Production
Longwall production footage per week
344
24106
306
371
338
230
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
Trough of Sandstone Channel at Wall # 29
Base of Sandstone
INBY OUTBYWALL #33
WALL #27
Drawslate
Pittsburgh Seam
5 F
ee
t
Vertical Scale
Frac Hole Locations and Frac Stage Horizons
Frac Process
Perforations were shot into the casing at the targeted horizons to pre-fracture 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 resultInitial 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
FL AC3D 3.10
Itasca Consulting G roup, Inc.M inneapolis , M N USA
©2006 Itasca Consulting G roup, Inc .
Step 11503 M odel Perspective16:38:18 Thu Jul 26 2012
Center: X: 2.000e+000 Y: 3.860e+002 Z: 1.400e+001
Rotation: X: 0.000 Y: 0.000 Z: 90.000
Dis t: 1.361e+003 M ag.: 18.2Ang.: 22.500
Job T itle : F-21 Sandstone Frac-After
View T itle :
Z o n e E x tra 1 M agfac = 1.000e+000 Live m ech zones shown G radient 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
FL AC3D 3.10
Itasca Consulting G roup, Inc.M inneapolis , M N USA
©2006 Itasca Consulting G roup, Inc .
Step 15221 M odel Perspective16:37:57 Thu Jul 26 2012
Center: X: 2.000e+000 Y: 2.138e+002 Z: 1.400e+001
Rotation: X: 0.000 Y: 0.000 Z: 90.000
Dis t: 1.361e+003 M ag.: 18.2Ang.: 22.500
Job T itle : F-21 Sandstone Frac-Before
View T itle :
Z o n e E x tra 1 M agfac = 1.000e+000 Live m ech zones shown G radient Calculation
1.4037e+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
Flac3D Model
Without Frac
Massive Sandstone
Clayey Shale
Longwall face
FL AC3D 3.10
Itasca Consulting G roup, Inc .M inneapolis , M N USA
©2006 Itasca Consulting G roup, Inc .
Step 15221 M odel Perspective14:55:06 Wed Jul 18 2012
Center: X: 1.585e+000 Y: 2.107e+002 Z: 8.023e+000
Rotation: X: 0.000 Y: 0.000 Z: 90.000
Dis t: 1.361e+003 M ag.: 18.2Ang.: 22.500
Job T itle : F -21 Sandstone Frac-Before
View T itle :
Z o n e E x tra 1 M agfac = 1.000e+000 Live m ech zones shown G radient 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
Shear stress, psi
With Frac Frac horizon
15 ft
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
LongwallVisual
Analysis
Ming Direction
Dec. 20, 2011
Face Monitoring and Evaluation
Face Monitoring and Evaluation
Face Monitoring and EvaluationLongwall production footage per week
240
124
232
142
115
194
323
F21—SS fraced
344
24106
306
338
230
F20—SS not fraced
Conclusions
Successful application of hydraulic fracturing technique.
Successful application of LVA software.
Improve safety and increase productivity.
Thanks!
Questions?