Elements of completions include:

• casing

• cement

• perforating and sand or gravel packs

• production equipment: tubing, packers

• stimulation

• surface flow control - wellhead or Christmas tree

Well Completions

Casing & Cement

1. supports the sides of hole

2. prevents unwanted

communication of fluids and

pressure between different

formations,

3. particularly to protect fresh water

zone near the surface

4. allows control of pressures

5. provides a 'base- for surface and

subsurface equipment

Cementing

Schematic of cement

placement

Courtesy of Allen & Roberts

Courtesy of Allen & Roberts

Cementing

Cross-section

Illustrating

Potential fluid

migration

CC: 20127800 Spud Date 06/30/04

KB: 22' WI: 100% NRI: 100%

GL: 413' 11" 5000PSI X 9-5/8" SOW casing head

June 2004 - Well drilled

7/21/2004 - Perforate Pettet, breakdown w/ PPI tool

7/29/2004 - Acidize Pettet comp w/ 6000 gals 15% HCl

9/10/2004 - Relocate packer to 7287' to isolate lwr perfs

11/20/2004 - Perf, breakdown, and acidize Transition zone

223 jts. 2-3/8 4.7# L-80 8rd tbg

Weatherford AS1-X @ 7,212'

EOT @ 7,219.35'

Pettet Completion (7/2004)

Perf: 7239-45', 7250-54', 7268-70', 7288-90', 7298-302'

7315-19', 7324-30', 7337-40', 7372 -76'; 7395-97'

Perforate 4 SPF, top down 15% HCL

Breakdown and Acidize each interval.

Transition Zone (11/2004)

Perfs: 7456-52', 7472-80' w/ 4 SPF

Breakdown and acidize w/ 1400 gals 15% HCl

Commingle w/ Pettet

Travis Peak - Fluvial (12/2004)

Perf: 7705-12', 7669-82'; 7645-48'

CO2 Frac w/ 47,000 # 20/40 resin coated

TD: 7,825' MD

Directions: At Buffalo, turn right onto FM 75 & go 1000 yards, turn left onto FM 164. Travel 18 miles on FM 164 to FM 3371, turn left onto 3371 & go

approx 8.1 miles to LCR 750. Turn left onto LCR 750 & go approx. 7 mile to location on the right.

9 5/8", 36 lb/ft, K-55,LTC @ 932'. Cemented w/ 380 sks

5 1/2", 17&15.5# K-55 LTC@ 7,825' Cmt w/1070sxs

Wellbore Diagram

And History

Openhole completion

Perforated completion

Perforating

Charge detonation Perf tunnel in test target

Courtesy of Schlumberger

Perforating

Courtesy of Schlumberger Courtesy of Halliburton

Techniques for perforating wells

Openhole Cavity Completion

Procedure

• Set casing at top of Fruitland zone

• Drill the Fruitland underbalanced

• Surge the coal, inducing significant caving and sloughing, forming a cavity

• As a result, stress relief occurs in the coal opening the natural fractures

• Run an uncemented liner with predrilled perforations

• Run lift equipment if necessary

Pre-perforated liner

Gravel pack completion

• Developed in the 1940s, today hydraulic fracturing (fracing) is widespread as a

result of technological advances and the need to tap previously believed

uneconomic resources.

• Hydraulic fracturing is the injection primarily of water and sand under high

pressure into the producing formation, creating fissures in the rock that allows a

pathway for oil and gas to migrate to the wellbore

• Hydraulic fracturing occurs at great depths, typically 5- 10,000 ft.

Simplified diagram of equipment for hydraulic fracturing (source: U.S. D.O.E.)

Stimulation hydraulic fracturing

Stimulation

Stimulation hydraulic fracturing

Pressures, stresses and rock properties involved in vertical fracture propagation (Allen & Roberts, 1982)

Stimulation hydraulic fracturing

Stimulation

• Frac fluid is typically 99.5%

water and sand and 0.5%

chemically based additives.

• The Frac fluids open the

fracture and transport

proppant

• The Proppants (sand)hold the

fracture open and provide a

highly conductive path for

fluid to flow into the

wellbore

Stimulation hydraulic fracturing

Jacob Garza of Cheapeake Energy pours a

chemical mixture called cross linked gel that is

mixed with sand used in the hydraulic

fracturing process at a Chesapeake site in South

Texas' Eagle Ford Shale (Photo: John

Davenport/San Antonio Express-News)

Stimulation hydraulic fracturing

Compound Purpose Common application

Acids Helps dissolve minerals and initiate fissure in rock (pre-fracture)

Swimming pool cleaner

Sodium Chloride Allows a delayed breakdown of the gel polymer chains

Table salt

Polyacrylamide Minimizes the friction between fluid and pipe

Water treatment, soil conditioner

Ethylene Glycol Prevents scale deposits in the pipe

Automotive anti-freeze, deicing agent, household cleaners

Borate Salts Maintains fluid viscosity as temperature increases

Laundry detergent, hand soap, cosmetics

Sodium/Potassium Carbonate

Maintains effectiveness of other components, such as crosslinkers

Washing soda, detergent, sopa, water softener, glass, ceramics

Glutaraldehyde Eliminates bacteria in the water

Disinfectant, sterilization of medical and dental equipment

Guar Gum Thickens the water to suspend the sand

Thickener in cosmetics, baked goods, ice cream, toothpaste, sauces

Citric Acid Prevents precipitation of metal oxides

Food additive; food and beverages, lemon juice

Isopropanol Used to increase the viscosity of the fracture fluid

Glass cleaner, antiperspirant, hair coloring

Source: DOE, GWPC: Modern Gas Shale Development in the United States: A Primer (2009)

Typical shale Fracturing Mixture Makeup Typical Chemical Additives Used in Frac

Water

More

complex

configuration?

Courtesy of Devon

Technical challenges… stimulation

-3000

-2500

-2000

-1500

-1000

-500

0

500

1000

1500

-1000 -500 0 500 1000 1500 2000 2500 3000

West-East (ft)

So

uth

-No

rth

(ft

)

Well A

Well B

Well C

Well D

Well E

Monitor

Well

Frac

Well

FRACTURE DIAGNOSTICS -

MICROSEISMIC

FRACTURE DIAGNOSTICS - MICROSEISMIC

Multi-Zone

Stimulation

• Unequal Fracturing

Activity

• Some Sands

Unstimulated

• Depleted Sands May

Fracture Most

Lenticular Sandstone Case

Technical challenges…stimulation

7100

7200

7300

7400

7500

7600

7700

-400 -300 -200 -100 0 100 200 300 400

Distance Along Fracture (ft)

Dep

th (

ft)

Unequal Distribution of Fracturing

Activity

Side View

Gamma Log

7100

7200

7300

7400

7500

7600

7700

-400 -300 -200 -100 0 100 200 300 400

Distance Along Fracture (ft)

Dep

th (

ft)

Unequal Distribution of Fracturing

Activity

Side View

Gamma Log

– How to acquire continuous,

realtime, insitu monitoring of

production, pressure data?

– How to identify bypassed pay

zones?

– How to stimulate multiple pay

zones?

20 to 40 pay Intervals

over 3000 ft

4500

5000

5500

6000

6500

7000

7500

0 100 200

Gamma Ray

De

pth

(ft

)

Technical challenges…

production performance

Horizontal well completions

Technical challenges…stimulation

Technical challenges…stimulation

Example of MSG for multiple stages in a horizontal well