Fracture Geometry from Microseismic. Norm Warpinski

Transcription

1 Fracture Geometry from Microseismic Norm Warpinski Pinnacle A Halliburton Service

2 Hydraulic Fracturing: Models Versus Reality Conceptually, fracturing is a simple process Elastic behavior Planar fractures Conservation of mass & momentum Reality is more interesting Complex fracture Crosslinked gel 3 Stages of colored sand Black, red, then blue Substantial mixing and layering of sand stages

3 Hydraulic Fracturing in the Barnett Initial waterfracs in vertical wells in the Barnett resulted in a series of bashed wells Prior to microseismic monitoring, the actual mechanism was unclear Bashed offset wells

4 Microseismic Monitoring An Engineering Tool Microseismic i i monitoring i is a valuable tool for optimizing Well layout Well spacing Stage lengths Perf clusters and/or valves & packers Stimulation design Complexity Calibrated fracture model Focus now: Providing the most accurate event locations and maximum viewability for correct decisions Engineering i applications using microseismicity Is it possible to extract other information from the microseismicity SPE , Mayerhofer et al., Seneca Res. SKTL Shale Marcellus Onondaga

5 2011 HALLIBURTON. ALL RIGHTS RESERVED. Downhole microseismic monitoring Array of receivers Positioned in nearby well Approximately at the depth of the treatment 3-component geophone systems ¼ to ½ msec sampling P-S Separation P P Moveout S S Moveout State-of-the-art microseismic receiver arrays Calibrated Array apertures Fiber-optic i wirelines Velocity of m Model Vertical Up V Clamp Arm In Back H2 H1 Tri-Axial Sensors (Geophones) Wall-lock clamped tools 5

6 M-Site Length & Azimuth Validation Intersecting Well Drilled Prior To Fracturing Microseismic Events Recorded During Fracturing & Compared At Time When Pressure Began To Increase In The Intersecting No orth (ft) N74W MWX-3 MWX2 MONITOR AT INTERSECTION Well West-East t (ft) Primary validation experiments: M-Site microseismic, tiltmeters, intersection wells, tracers, pressure interference Mounds Drill Cuttings microseismic, tiltmeters, intersection wells, tracers Mitchell Barnett microseismic, surface & downhole tiltmeters, offset wells INTERSECTION WELL

7 Fracture Behavior: Wide Variations Sandstones Relatively planar Piceance basin Mesaverde example Barnett Shale Intrinsic complexity Low stress bias Weak natural fractures Enhanced by slick water stimulations Other Shales? Full spectrum of behavior South-Nort th (m) Barnett Mesaverde West-East t( (m)

8 Microseismic Mapping Results N45 E to N55 E X f = 600 to 1,000 ft (most events <500 ft) h f = ft Pressure interference for all fractures SKTL Shale Marcellus Well 1H Fracture Stimulation Slurry Flow Rate (bpm) Slurry Density (lbm/gal) 200 Surf Press [Csg] (psi) Bottomhole Press (psi) ? Pressure rise BH Pressure Gauge data in Well 2H Well 2H (completed first) Well 1H (completed next) Time (min) SPE , Mayerhofer et al., Seneca Res

9 Production Interference Core Area Barnett Shale Shut-ins cause corresponding rate increase in other well

10 Microseismic Monitoring: Unconventional Reservoirs Multi-stage lateral Packer Completion Excellent geometry values for modeling Added value by integrating with other diagnostic technologies DFIT s Calibrated model SPE , Canadian sedimentary basin example

11 Modeling example Calibrated Model and Proppant Transport Modeled fracture geometry matched to the measured microseismic geometry Proppant transport models calculated from the given data From this data, long term production estimates can be made

12 Cardium Example: Treatment Well Relatively planar fractures Mostly consistent lengths and height growth Easily amenable to modeling Observation Well ~70 m 3 Nitrified Gel ~3 m 3 / min ~20 tonne sand

13 Horn River example: variable complexity (faulting) C-99-H: 6 fracs; 2.9 MM lb sand; 3.7 MM gal water Muskwa

14 Example Maps: Height Growth Variable containment t in shales Containment (e.g., Eagle Ford & Barnett) Bounded by carbonates Upward growth (e.g., Marcellus & Haynesville) Continuous shale SPE GMX Resources 600 ft Haynesville Example Austin Chalk Eagle Ford Example Marcellus Example Eagle Ford 900 ft Buda SPE , Magnum Hunter Resources, Inc. SPE ,Curry et al, 2010

15 Microseismic Source Analysis Microseismic mapping is based on the distribution of microseismic events Envelope surrounding fracture Waveforms clearly contain information about the fault planes Radiation pattern is a function of the orientation ti & direction of slippage Some useful information should be extractable from the waveforms Magnitude, size, stress drop Fault mechanism Can we use this information to further understand the hydraulic fracture? Tied directly into the hydraulic fracturing geomechanics

16 Microseismic Moment & Magnitude Analysis Analyses Moment (strength) M o = G A d G shear modulus A slippage area d distance moved cm-s) Displacemen nt Spectrum ( 1.0E E-10 Magnitude (log scale) 1.0E-11 M w = 2 / 3 { log 10 [ M o ] const } Spectral analysis for moment and size Brune approach 1.0E E-13 f c Ω Ο Frequency (Hz) M o = 3 s 4πρV F c RΩ o r o = KcV 2π f s c

17 Microseismic Viewing Capabilities How Far Can We See? 0 Faults -0.5 Muskwa Faults: >2,000 m Marcellus Barnett Woodford Mo oment Magniitude -1 1 EagleFord Montney -1.5 Shales: >1,200 m Some Variabilityy In Viewing Limit Distance (m)

18 Energy & Volume: Microseisms Versus Fracture Microseismic energy Magnitude -2 -> ~60 J Magnitude -1 -> ~2000 J 500 microseisms in a typical fracture treatment Magnitude -2: ~30 kj Magnitude -1: ~1000 kj Hydraulic fracture Based on horsepower kj Based on fracture work kj Microseismic volume (all tensile) Magnitude -2 -> m 3 Magnitude -1 -> m microseisms in a typical fracture treatment Magnitude -2: m 3 Magnitude -1: 1.33 m 3 Hydraulic fracture Volume injected 1500 m 3 An analysis of source mechanisms cannot provide information about the hydraulic fracture

19 Mapped Microseismic Height: North American Shales Top: shallowest microseism; Bottom: deepest microseism Top: shallowest microseism; Bottom: deepest microseism Typical aquifer depths SPE Depth, m Fracture tops Fracture bottoms Average perforation depth Fracture stages

20 Environmental Questions: Microseismicity in Shale Basins Thousands of fractures monitored No significant seismic activity Relaxed basins Minimal tectonics Depth, m Barnett Marcellus Eagle Ford Woodford Haynesville Horn River SPE Moment magnitude

21 Conclusions Fracture diagnostics, and microseismic mapping in particular, have provided important understanding of hydraulic fracturing Fracture length Fracture complexity (stress bias and natural fractures) Fracture height growth Effects of geohazards Interactions between wells and stage Completion effects (plug and perf, packers & sleeves, etc.) Fracture diagnostics provide input for calibrated models and improved fracture design and analysis Geologic complexity

22 Questions?