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Value of Horizontal Shale Evaluation
DAN BULLER Global Advisor
Unconventional Optimization Formation & Reservoir Solutions
2 © 2011 HALLIBURTON. ALL RIGHTS RESERVED.
Defining the Sweet Spot – Vertical to Horizontal
Higher index of brittleness and low plasticity = highest fracture complexity & most surface area
Highest effective porosity (most free gas or oil)
Lowest amount of VTI mechanical anisotropy (horizontal clay layering) and highest amount HTI anisotropy (vertical fracturing)
3 © 2011 HALLIBURTON. ALL RIGHTS RESERVED.
Pseudo Brittleness from Rock Mechanics
SPE 115258
YM_BRIT = ((YMS_C-1)/(8-1))*100
PR_BRIT = ((PR_C-0.4)/(0.15-0.4))*100
BRIT = (YM_BRIT+PR_BRIT)/2
4 © 2011 HALLIBURTON. ALL RIGHTS RESERVED.
Pseudo Brittleness from PR & YM ShaleLog® Service – Haynesville Shale
Core “Calcite” facies. Lowest Clay
Slightly higher Pseudo Brittleness in upper = better horizontal target
Top
Bottom
5 © 2011 HALLIBURTON. ALL RIGHTS RESERVED.
Effective Porosity & 3-D Stress (VTI-HTI) Core Calibrated GEM Volumetrics & Oriented X-Y Dipole
Bossier Shale Haynesville CV Lime
6 © 2011 HALLIBURTON. ALL RIGHTS RESERVED.
SPE 115258
Shale Completion Strategy: Based on Formation Pseudo Brittleness
Brittleness Fluid System Fracture Geometry Fracture Width Closure Profile
70% Slick Water
60% Slick Water
50% Hybrid
40% Hybrid
30% X-Linked
20% X-Linked
10% X-Linked
Brittleness Proppant Concentration Fluid Volume Proppant Volume
70%
60%
50%
40%
30%
20%
10%
Liquid Production
Low
High
High
Low
Low
High
Youngs Modulus
7 E 6
6 E 6
5 E 6
4 E 6
3 E 6
2 E 6
1 E 6
Low
High
Barnett
Marcellus
Eagleford Haynesville
Barnett
Marcellus
Eagleford Haynesville
7 © 2011 HALLIBURTON. ALL RIGHTS RESERVED.
Reality Check – Current Horizontal Performance
Reason: Sweet spot targeted, but shales are rarely homogeneous over long horizontal course lengths and LWD GR steering doesn’t reflect complex reservoir behavior
Statistical Analysis of all available horizontal Production Log data in North America from equal spaced plug/perf stage frac’s supports: 61% of frac clusters produce less than the mean for any given well 41% of clusters produce less than a half of the mean (bottom quartile) for any given well 34% of clusters may have entry, but produce less than detectable resolution of the PL logs
8 © 2011 HALLIBURTON. ALL RIGHTS RESERVED.
– Real Time Steering – Min of 20’ Mudlogged Samples
collected at surface
– Thru bit/drill pipe conveyed logging
– Tractor, E-Coil, Pumpdown
– Tractor-While-Logging, E-Coil, Memory
Horizontal Evaluation Options
Geo Steering Open Hole – LWD Dipole & Imaging (Density,
Resistivity, GR, Acoustic) – LaserStrat
Open Hole Wireline
– OH Logging Suite – UltraSlim Logging
Cased Hole Evaluation
– RMT- Neutron Capture Spectroscopy & CHI Model
– Cased Hole Wave Sonic
Production Logs – CAT – SAT – RAT
9 © 2011 HALLIBURTON. ALL RIGHTS RESERVED.
Buller et al (2010) SPE 132990
VTI Anisotropy Viewed by Sonic Logs
10 © 2011 HALLIBURTON. ALL RIGHTS RESERVED.
Surveydegrees85 95
True Vertical Depthfeet 0150
Real-Time Gamma Rayapi0 150
Rate of Penetrationfeet per hr500 0
Real-Time AFR Image1 256
Top Right Bottom Left Top
1 16
8 7
6
5
4
3
2 15 14
13
12
11
10 9
Real-time Images for Wellbore Placement
Gamma Ray, Density and High Resolution Resistivity
GABI™
AFR™
ALD™
11 © 2011 HALLIBURTON. ALL RIGHTS RESERVED.
LaserStrat® – LIBS Chemostratigraphy Sample Cuttings Mechanical Properties
12 © 2011 HALLIBURTON. ALL RIGHTS RESERVED.
LaserStrat® Steering Application Target – Red & Green Upper Haynesville, Blue Lower Haynesville, 30% in zone
13 © 2011 HALLIBURTON. ALL RIGHTS RESERVED.
No frac issues encountered & hybrid gel design Brittleness index varying between 37-55
2010
Horizontal Cased Hole Shalelog Haynesville Core Area – Pulsed Neutron RMT Tool
14 © 2011 HALLIBURTON. ALL RIGHTS RESERVED.
Post Frac Production Log – day 45, well flowing 9MM
Brittleness Index vs. Gas Production
15 © 2011 HALLIBURTON. ALL RIGHTS RESERVED.
BP George A9H – 9 of 10 Water Fracs Placed – PL rate 8.2 MMCF/D
16 © 2011 HALLIBURTON. ALL RIGHTS RESERVED.
Frac Results Simplified
Near Wellbore Region (1-2 ft.) Higher injection pressure
Pad and proppant entry
High pressure drawndown during flowback
Higher Clay Interval Smaller effective
fracture width
Increased likelihood of screenout
Lower gas production higher embedment
Lower Clay Interval Wider effective fracture
width
Better chance of placing proppant and achieving complexity
Better gas production
17 © 2011 HALLIBURTON. ALL RIGHTS RESERVED.
Horizontal Evaluation Conclusions & Recommendations
Because of layered horizontal anisotropy effects, optimal evaluation should include horizontal open hole LWD dipole or cased hole cross dipole sonic for slow & fast shear detection. ALD density imager adds direct mechanical properties
Triple Combo & lithology inputs from either LWD suite or RMT Neural Net can be used for total clay volume and a horizontal anisotropy estimate by proxy
Laserstrat sample analysis is a viable mechanical proxy unless shale is too homogenous over horizontal, (assumes good hole cleaning)
Use formation evaluation for frac optimization. Plan frac stages by similar mechanical properties. Fewer entry points per stage appear reasonable in softer shales
Lateral placement rules dictate well performance. Frac’s placed in clay rich, or other layered, highly horizontal anisotropic rock, will underperform because of near well “chokes” and limited height growth
18 © 2011 HALLIBURTON. ALL RIGHTS RESERVED.
Thank you. Questions?
Market J., Quirein J., Pitcher J, Hinz D., Buller D., Al-Dammad C., Spain D., Odumosu T. 2010. Logging-While-Drilling in Unconventional Shales. Paper SPE 133685 presented at the SPE Annual Technical Conference and Exhibition, Florence, Italy, 19–22 September.
Buller D., Hughes, S., Market, J., Petre, E., Spain D., Odumosu T. 2010. Petrophysical Evaluation for Enhancing Hydralic Stimulation in Horizontal Shale Gas Wells. Paper SPE 132990 presented at the SPE Annual Technical Conference and Exhibition, Florence, Italy, 19–22 September.
Mullen M., Pitcher J., Hinz D., Everts M., Dunbar D., Carlstrom G., Brenize G. 2010 Does the Presence of Natural Fractures Have an Impact on Production? A Case Study from the Middle Bakken Dolomite, North Dakota. Paper SPE 135319 presented at the SPE Annual Technical Conference and Exhibition, Florence, Italy, 19–22 September.
J.Market, C.Bilby, and G.Varsamis, 2011, Introducing the First LWD Crossed-Dipole Sonic Imaging Service prepared for presentation at the SPWLA 52nd Annual Logging Symposium held in Colorado Springs, Co, USA, May 14-18, 2011.