Barnett Shale and Other Unconventional Gas Play

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Barnett Shale and Other Unconventional Gas Play

• Kent A. Bowker
• Bowker Petroleum, LLC
• HAPL Technical Workshop, 2008

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Barnett of North Texas Operational Update

• 120 firms in Newark East that operate wells
  (many more with an interest)
• Currently about 3.5 BCF/D 5000 BC/D
• About 8000 wells drilled to date
• 140 rigs running with more anticipated each week
• Center of the worlds stimulation horsepower

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Total Equivalent Gas Production Newark East
(Barnett Shale) Field, by Year of First Production
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Gas Production Newark East Daily by Date
1982-2001
Gas Production (MMCF/D)
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(No Transcript)
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Denton
Wise
Viola/Simpson
Muenster Arch
MEC K. Keele 3
Core Producing Area
Eroded
Newark East Index Map
Tarrant
Gas Window
Oil Window
Feather Edge
Marble Falls
Fort Worth
Parker
Johnson
Ouachita Thrust Belt
Enre (Chevron) Mildred Atlas 1
20 Miles
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Index Map
Viola Pinchout
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Cross Section
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Development History of the Barnett Play as
Revealed in One Well

• C.W. Slay 1, Southeast Wise County

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First StageTheoretical Testing of a New Shale
Play
Monthly Gas Production
Year
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The only thing that interferes with my learning
is my education.

A.
Einstein
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Second StageTheoretical Testing of a New Shale
Play
Monthly Gas Production
Year
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Third StageTheoretical Testing of a New Shale
Play
Monthly Gas Production
Year
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Newark East Discovery WellC.W. Slay 1
Monthly Gas Production
Year
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Natural Fractures
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• Debris-flow deposit
• Shale intraclasts
• Single depositional event

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• Poorly-sorted debris-flow deposit
• Sharp basal contact at 25 degrees
• Fining upward

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Open Natural Fractures

• Open natural-fractures are not important to the
  production of gas from the Barnett

The Barnett isnt a naturally-fractured shale
play its a shale-that-can-be-fractured play.
Daniel Miller, 2004
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• Open natural fractures would actually be
  detrimental to the gas potential of the Barnett
• Open natural fractures are truly rare in the
  Barnett (despite descriptions based on image
  logs look at core)
• Image logs are excellent for determining the
  direction of maximum horizontal stress, however

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• Structural flexures and faults are detrimental to
  Barnett production
• All that being said, there is a reason some areas
  of the field are better than others

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Evaluation of Critical Parameters

• Thermal Maturity (predict gas or oil)
• Gas Content
• Gas Composition
• Adsorption Capacity
• Porosity Permeability
• Shale Composition
• Stress Orientation
• Structural Setting
• Natural Fracture Characterization

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Thermal Maturity

• Use to predict if dry gas, wet gas, or oil
• Vitrinite reflection
• Thermal gas extract
• Rock eval (T-max)
• Nature of shallow production

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Gas Content

• On-site canister desorption
• Use whole core in initial evaluation wells
• Take many samples because of statistical
  variability
• Most important parameter

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Gas Composition

• Take samples from mudloggers gas line
• Take samples during the course of canister
  desorption (change in composition during
  desorption)
• Determine what gases to use for adsorption
  isotherm tests

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Adsorption Capacity

• Methane isotherm
• Other gases if necessary
• Correct temperature and extend to beyond
  reservoir pressure
• Determine if reservoir fully saturated

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Barnett Isotherm Comparison
120 100 80 60 40 20 0
Enre (Chevron) Mildred Atlas 1 8121.5 ft TOC
4.77 180º F
0 500 1000 1500
2000 2500 3000 3500
4000 4500
Gas Content (scf/ton)
Mitchell Energy TP Sims 2 7675 ft TOC 4.79 175º
F
Pressure (psia)
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Porosity and Permeability

• New techniques available
• Determine free gas in place
• Permeability value is of little use (diffusion)

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Mercury-Porosimetery Analysis Barnett Shale
1 .8 .6 .4 .2 0

• Introduction
• Geologic Setting
• History of Development
• Exploration Strategies

NORMALIZED PORE VOLUME DISTRIBUTION
-2 -1 0 1
2
10 10 10 10 10
PORE THROAT RADIUS (MICRONS)
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Shale Composition

• Organic content
• Clay volume and types present (water sensitivity)
• Clay adsorption?

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Stress Orientation

• Wellbore breakouts from image logs
• Drilling-induced fractures from image logs
• Wellbore shape from micro-caliper logs
• Shear-wave seismic
• Important for orientation of well pattern and
  horizontal wells

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Structural Setting

• Faults bad for Barnett gas trend, but may enhance
  production in other plays
• Understand basins history burial history,
• heat flow, etc.

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Natural Fracture Characterization

• Healed fractures are probably important to
  Barnett production because they act to complicate
  the pattern of induced hydraulic fractures
  (complex fracture pattern)
• But open fractures are critical to other plays
  (e.g., Antrim Shale)
• Open vs. cemented natural vs. induced

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Barnett Shale

• Its own source rock
• Its own reservoir
• Its own trap
• Its own seal

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- Buoyancy- Pore pressure- Partial pressure
of CH
- Capillary pressure- Rock strength/
Confining stress- Langmuir pressure
4
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Newtonian Physics vs. Quantum Mechanics

• Need to think beyond porosity, permeability, and
  fractures
• Understand diffusion and adsorption - know the
  reservoir at the molecular level

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Fracture Stimulation

• Key to success in the Barnett depends on an
  effective fracture stimulation
• Contacting as much of the reservoir and staying
  out of water-saturated formations are the goals
  of the frac

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FracSeis Analysis - Map View
First Stage Perf Clusters
First Stage Frac
Second Stage Frac
Treatment Well
Observation Well
O
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The Barnett works because it contains a bunch of
gas and we can frac the bejeepers out of it
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Barnett Shale and Other Unconventional Gas Play

• Kent A. Bowker
• Bowker Petroleum, LLC
• HAPL Technical Workshop, 2008