This presentation is a result of intensive search about unconventional shale gas resources. These slides was presented at SPE Egyptian section educational week. Authors : Karim Magdy, Suez University, karim_magdy5298@yahoo.com Karim Mohamed Kamel, The British University in Egypt, kareem.kaml@gmail.com Ahmed Omar Eissa, Suez University, ahmedomar92@yahoo.com Ahmed Alhassany, Al-Azhar University, Al7assany@gmail.com Yunus Ashour, Alazhar University Eng.yunusashour@Gmail.com Mahmoud Elwan, Cairo University, elwan_92@hotmail.com Mahmoud Abbas , Suez university mahmoudabbas15@gmail.com Khaled Elnagar, Suez University KhElnagar@outlook.com

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SPE YP EDUCATIONAL WEEK 2014

2. Unconventional Shale Gas
Presented by Team 3
SPE YP Educational Week, SPE Egypt
Energy For The Future

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Objective:- “Make a detailed study on shale
gas trying to show its extraction process and its
challenges especially for application in Egypt”
.
Vision & Objective
Vision:- “Set a primary base criteria for shale gas
characteristics and its potential helping in further
estimation of it. ”

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WORK PROGRESS
Introduction
1 Shale
properties
2
Reservoir
characterization
3
Drilling
4
Hydraulic
frac
5 Surface
processing
6
Economics
7

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Introduction

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World consumption

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World Facts
US production by fuelUS production by source

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Shale Gas Revolution
4 Major Changes
1. A low cost era is beginning
2. Petrochemical will be a Gas
based industry
3. Gas power generation will
increase
4. All of the above will provide more
and more numerous future
careers

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Shale Gas Map 2013 – TRR in TCF
Algeria
707
USA
1161
China
1115
Argentina
802
Canada
573
Mexico
545
Australia
437
South Africa
390
Russia
285
Brazil
245
Others
1535

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G&G
PROPERTIES

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What’s Shale ??
Shale gas
• Natural Gas which is naturally trapped
within very fine grained sedimentary rocks
called shale or mudstone.
• Millions of years ago, the mud and silt that was
deposited in ancient oceans and lakes often
contained plant and animal debris. Over time
these sediments containing this organic material
were compacted and solidified through burial,
and with increasing temperature and pressure
formed shale and mudstone.

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Shale Different Forms
Fine Grained
Black Shale
Inter-bedded with
Coarser Siltstones
Fractured
Shale
• Shale and mud rich rocks often vary in color as well as grain size. Colors may
vary from dark brown or grey through to black shale

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• A measure of how much
pressure and temperature the
rock has been subjected to.
• More mature, higher gas ratio
• Vitrinite reflectance (% Ro),
where a value above
approximately 1.0%–1.1% Ro
indicates the organic matter is
sufficiently mature to generate
gas .
Thermal Maturity
Effective bulk permeability
in gas shale is typically
much less than 0.1 (md),
although exceptions exist
where the rock is naturally
fractured (Antrim shale)
Pore Space
amount of organic material
present > 2%
Total Organic Content
Characteristics for Potential Shale Gas

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Data Acquisition
Coring
For more Penetration through the target zone
Logging
For larger stimulated reservoir volume

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Gas Shale Coring
• Multi-scale Visualization
 High resolution micro-CT
(Computer Tomography)
 Dual beam SEM FIB: Focused
Ion Beam
• Gas injection & NMR
• GeoMechanics

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Shale lithology and mineralogy logging
Gamma-ray and Spectral Gamma-ray

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Density Log and Photoelectric
Factor (PE Log)
Neutron Log Sonic Log
Porosity Logs

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Laterolog
Induction log Micro-Resistivity Basics
Resistivity Logs
(Water Saturation)

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Nuclear Magnetic Resonance
(NMR LOG)
Borehole Temperature-
Logging
Other Logs

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Shale Gas Horizontal Production Logging
• Production Logging Measurements
• Horizontal Production Logging
• Horizontal Production Logging Challenges

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Shale Gas Reservoir !
What Do We Have to Consider?
Ultralow-Permeability
Triple Porosity Behavior
Gas Adsorption/Desorption
Nano-Pores Effect

22. Property Antrim Ohio New Albany Barnett Lewis
Depth (ft) 600–2400 2000–5000 600–4900 6500–8500 3000–6000
Net thickness (ft) 70–120 30–100 50–100 50–200 200–300
Bottom-hole temperature (_F) 75 100 80–105 200 130–170
TOC (%) 0.3–24 0–4.7 1–25 4.50 0.45–2.5
Total porosity (%) 9 4.7 10–14 4–5 3–5.5
Gas-filled porosity (%) 4 2.0 5 2.5 1–3.5
Water-filled porosity (%) 4 2.5–3.0 4–8 1.9 1–2
Permeability thickness 1–5000 0.15–50 NA 0.01–2 6–400
Gas content (scf/ton) 40–100 60–100 40–80 300–350 15–45
Adsorbed gas (%) 70 50 40–60 20 60–85
Reservoir pressure (psi) 400 500–2000 300–600 3000–4000 1000–1500
Pressure gradient (psi/ft) 0.35 0.15–0.40 0.43 0.43–0.44 0.20–0.25
Gas production (mcf/day) 40–500 30–500 10–50 100–1000 100–200
Well spacing (ac) 40–160 40–160 80 80–160 80–320
Recovery factor (%) 20–60 10–20 10–20 8–15 5–15
Gas in place (bcf/section) 6–15 5–10 7–10 30–40 8–50
Reserves (mmcf/well) 200–1200 150–600 150–600 500–1500 600–2000
Historic production area Otsego County, Pike County, Harrison County, Wise County, San Juan & Rio Arriba
Geological, Geochemical, and Reservoir Parameters for Five Shale-Gas Systems(Hill and Nelson
(2000))

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3. Adsorbed Gas
2. Natural Fractures
1. Matrix Pores
A “Triple porosity” Model is appropriate
to describe the gas storage mechanism
because it includes both the free gas
and adsorbed gas. Briefly speaking,
triple porosity is dual porosity system
combined with gas adsorption.
Triple Porosity Behavior
Gas Filled Pores

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Shale can hold significant quantities of gas
adsorbed on the surface of the organics in
the shale formation.
Adsorbed gas can be the dominant in-place
resource for shallow, organic-rich shales.
Gas Adsorption/Desorption

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Gas flow in Nano-pores cannot be described
simply by the Darcy equation.
Processes such as Knudsen diffusion and
slip flow at the solid ma-trix separate gas
flow behavior from Darcy-type flow.
Nano-Pores Effect

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Depletion of free gas stored in the
fracture network (Darcy Flow)
Gas Production Mechanisms
Depletion of free gas stored in the matrix
(Knudsen diffusion and slip flow in micropores)
Desorption of Adsorbed Gas
(Gas diffusion )

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Rate VS Time Curve
• Lasting one to three months
• The primary controlling variables are :
Fracture permeability
Fracture spacing
Effective lateral length.
• The response is dominated by:
Fracture permeability
The width of the stimulated area
• Secondary variables during the middle time
region are matrix porosity and net thickness.
• Important variables in the late time region are
Matrix permeability
Matrix porosity
Fracture spacing of any natural
fractures in the non-stimulated area.

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Estimate the OGIP
OGIP = Free Gas + Adsorbed
Gas
There`s a significant uncertainty
in the ultimate recovery of the
fields to which analogy might be
made.
Volumetric Method
The effect of adsorbed gas should
be included.
Adequate matches could be
obtained during history matching
and accurate predictions could be
made for future reservoir
performance.
Material Balance
The PDA for shale/tight
gas is different from
conventional methods
based on radial flow and
boundary dominated flow,
which were developed first
by Arps.
Decline Curve Analysis
The presence of massive multi-
cluster, multi-stage hydraulic
fractures only makes the reservoir
modeling of shale formation
more complicated.
Since hydraulic fractures are the
main reason for economic
production from shale, modeling
their behavior becomes one of the
most important aspects of
modeling storage and flow in
shale formations.
Numerical Simulation
Reserve Determination & Production Forecast for Shale Gas

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Shale Gas Development
Horizontal drilling
For more Penetration through the target zone
Multi-stage frac
For larger stimulated reservoir volume
Higher gas market price
For encouragement of investment

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Horizontal Drilling

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Drilling Process
• Period
May take from 90 to 120 days
• Function
Horizontal penetration to increase the
produced interval
• Number of Wells
4:8 wells as typical
12:16 wells may be possible
• Design
Stretched more than 3000 ft underground
3 millions Ib of steel and cement are used

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Drilling Considerations
Considerations
Longer Lateral
Faster
Higher Build
Rate
High Quality
Special Designed
Drill Bits
Rotary Steerable
System(RSS)

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Bits Products
New different drilling bits products for higher penetration
rate and less borehole problems
ONYX II Premium PDC Cutter
Improved thermal stability and abrasion resistance
through new materials and manufacturing
processes for increased footage and ROP in tough
formations.

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Drilling Fluid Challenges
Water Base
Mud
Tight
Spots
Shale
Instability
Stuck
Pipe
Hole
Pack Off
Torque
& Drag
WBM VS OBM
More drilling days were spent on the same
footage with WBM .

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Mud New Systems
Thedevelopmentofanewwaterbaseddrillingfluidsystemcompatiblewiththeseformationswouldbeanimportant
stepinthedevelopmentofshalegasdrilling.
The Terra-Max system
In addition to addressing the operator’s waste management issues,
use of the high-performance WBM achieved an average ROP of
about 50 ft/hr, which was comparable to ROP rates using OBM,
according to Baker Hughes.
Benefits
• Excellent wellbore stability
• Superior clay inhibition
• Enhanced rates of penetration
• Reduced torque and drag

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Completion

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Completion Characteristics
• Cost
USD 7.75 million for 5,000 ft laterals
USD 4.75 million for 2,500 ft laterals
• Cemented Laterals
Range from 2,500 to 5,300 ft
• Completion Fluids
18,000 bbl of slick water
200,000 lbm 100 mesh sand
• Types of Casing
75% Cased Hole
25% Open Hole

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Plug & Perf. VS OH Completion
Plug & Perf.
•75% of Shale gas wells
•More reliable
•Achieve better production
results
•Verifiable zonal isolation
•Indicate exactly where frac is
going
•More flexible if things don’t go
as planned
OH Completion
•25 % of Shale Gas wells
•No perforating needed
•Faster stimulation times
•No intervention with CT is
needed
•More stages can be
simulated in less time
•Greater reservoir contact
•Limited cementing operations
•Low Cost

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Rupture Disc Valve (RDV)
Challenge:
Overcome the costly, timely and risky first stage of Plug & Perf.
Rupture Disc Valve
• It is downhole valve exists as part of the casing string,
• It provides positive isolation and allows for a pressure integrity test of
the casing to be performed.
• The RDV is cemented in place and requires no changes to the cement
operation or chemistry.
• It is pressure activated and once the sliding sleeve in the valve is
opened, the wellbore fluid is exposed to the cement sheath in the
annular space then fracturing operation can begin.
• It saves 100,000 $ per each well.

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Hydraulic Fracture

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Frac Target
Simple Bi-wing.
Common used one in conventional reservoirs
Intensive Complex Frac.
Massive frac is needed for unconventional shale gas

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Frac Process
1. Pad injection
2. Increased prop concentrations
3. Flush
4. Pressure bled off
5. Recovery of injected fluids

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What frac. fluid will be used?
How effectively can it transport proppant and how it is
distributed?
Is the proppant strong enough and retain strength over the long
term?
Where did the frac. go and what did it touch (or not)?
What is the maximum length of lateral that can be placed into
the formation and effectively cleaned up after fracturing?
Is there a good lower frac. barrier?
How to make it safe and keep away from the ground water ?
1
Beginning With The End In Mind
2
3
4
5
6
7

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Common Practice
• Multi-stage frac
More than 30 stages per each well
• Huge amount of fluid
Between 3:5 million gallons of water
• High pump rate
Using slick water at 100 bbl/minute for longer frac
• Higher Horse power
More than 80 KHP is needed

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Open and
Closed Fractures
Some or all
may be filled with
Cement
Localized Tectonics
could create a second
fracture set which
could offset the
original fractures
Hydrocarbon
Expulsion and/or
Gas Cracking
could create a
new gas filled
fractures network
Frac Distribution in Shale Gas
Hydraulic frac. will
create fractures parallel
to the maximum
horizontal stress
Reactivation of pre-
existing fractures

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Frac Parameters
Frac Network Size
Higher SRV results in better well performance.
Frac Network Density
Small frac spacing results in better well performance

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Challenges
Main
Shale
Properties
Source
Availability
Land
Area
Shale properties
• low permeability
• brittleness properties
• natural fractures
Main challenges
Source availability
• Surface Water
• Groundwater
• Municipal Water
• Industrial Water
• Recycled Produced Water
• Collected Water
• Private Water Purchases
Land area
• 2:5 acre needed
• 2 frac crews with concentration of equipment
• Stockpiling for equipment transport
• Tanker trucks for water requirements

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Environmental Effects
• Air Pollution
 Equipment emits CO2 nearly 400 tons per well
during transportation of water, wastewater and
equipment
• Water Issues
 Chemicals added pollute aquifers or surface water
 Reducing the availability of water for essential
uses
• Flow back disposal
 Containing radioactive substances
• Other problems
 Short-term increase in traffic volume, dust and noise
 Induced seismicity into the ground

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New Technologies
Trying to confront the main challenges of lack sources and
provide new prop for more gas production
Broadband Sequence by SLB - Feb 19, 2014
- Features
Composite fluid; blend of degradable fibers and multimodal particles
- Re-fracturing operations
Perforating first interval
Temporary perf clusters isolation
No need for bridge-plug
- Benefits
Stimulating maximum perfs and zones of increased initiation pressure
Increased Stimulated Reservoir Volume SRV
Increased production by 20% and PI by 6x and decreased plug-and-
perf completion time and cost by 40%

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New Technologies
Trying to confront the main challenges of lack sources and
provide new prop for more gas production
LaserFrac
Features
Thermal induced stress
Laser as a source of heat
Thermal cracking
Requirements
Brittle materials are particularly sensitive to thermal fracture
Expansion and contraction of grain
Benefits
Eliminate the source availability problem

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TREATMENT OF SHALE GAS PRODUCED WATER FOR DISCHARGE:
How we can use the produced water ?
1. Injection
2. Surface Discharge/Beneficial use
3. Reuse in HVHF
Challenges :
1. Water quality
2. High TDS concentrations limits treatment options
3. All treatment processes results in a test stream –
maybe liquid, solid or both.
4. All of the PW management options and
treatment goals may be inter-related.

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Reuse of Flow Back Water in HVHF
Benefits:
• Reduced withdrawals (and associated concerns)
• Reduced Disposal needs
• Reduced environmental concerns
Challenges
• Blended water must be suitable for fracture fluid
• May require treatment for TDS, scale, microbes
• Not necessarily a “no-treatment” option

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Economics

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Resources Classification

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Impact of Technology and Economic Conditions on Gas Recovery

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Unconventional Economics
Principal reasons why the development of shale plays remains economically risky is
that:
• The High Uncertainty :
The estimated ultimate recovery (EUR) is poorly constrained during the early stages of field development. A
stochastic approach that accounts for the spatial spread of well productivities is included, using production
volume probabilities P10–P50-P90.
• The Huge number of wells that have to be drilled
Each well recovers less gas per well when compared to a well in a conventional reservoir, many more wells
have to be drilled in unconventional reservoirs to recover the gas. The need for drilling more wells translates
into the need for higher investment and higher economic risk when it comes to the management of
unconventional gas reservoirs.

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Thank You !