Well Completions

1 Well Completions Elements of Completions include: casing cement perforating and sand or gravel packs production equipment: tubing, packers stimulation surface flow control - wellhead or Christmas tree 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 Cementing Cross-section Illustrating Potential fluid migration Courtesy of Allen & Roberts CC: 20127800 Spud Date 06/30/04.

2 KB: 22' WI: 100% NRI: 100%. Wellbore Diagram GL: 413' 11" 5000 PSI X 9-5/8" SOW casing head And History 9 5/8", 36 lb/ft, K-55,LTC @ 932'. Cemented w/ 380 sks 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 # L-80 8rd tbg Weatherford AS1-X @ 7,212'. EOT @ 7, '. 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'.

3 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 5 1/2", 17& # K-55 LTC@ 7,825' Cmt w/1070sxs 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 miles to LCR 750. Turn left onto LCR 750 & go approx.

4 7 mile to location on the right. 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 Stimulation hydraulic fracturing 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.

5 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: ). Stimulation Stimulation hydraulic fracturing Pressures, stresses and rock properties involved in vertical fracture propagation (Allen & Roberts, 1982). Stimulation hydraulic fracturing Stimulation Stimulation hydraulic fracturing Frac fluid is typically water and sand and chemically based additives.

6 The Frac fluids open the fracture and transport proppant The Proppants (sand)hold the fracture open and provide a highly conductive path for Jacob Garza of Cheapeake Energy pours a fluid to flow into the chemical mixture called cross linked gel that is mixed with sand used in the hydraulic wellbore fracturing process at a Chesapeake site in South Texas' Eagle Ford Shale (Photo: John Davenport/San Antonio Express-News). Stimulation hydraulic fracturing Typical shale Fracturing Mixture Makeup Typical Chemical Additives Used in Frac Water Compound Purpose Common application Helps dissolve minerals and Acids initiate fissure in rock (pre- Swimming pool cleaner fracture).

7 Allows a delayed Sodium Chloride breakdown of the gel Table salt polymer chains Minimizes the friction Water treatment, soil Polyacrylamide between fluid and pipe conditioner Automotive anti-freeze, Prevents scale deposits in Ethylene Glycol deicing agent, household the pipe cleaners Maintains fluid viscosity as Laundry detergent, hand Borate Salts temperature increases soap, cosmetics Maintains effectiveness of Washing soda, detergent, Sodium/Potassium other components, such as sopa, water softener, glass, Carbonate crosslinkers ceramics Disinfectant, sterilization of Eliminates bacteria in the Glutaraldehyde medical and dental water equipment Thickener in cosmetics, Thickens the water to Guar Gum baked goods, ice cream, suspend the sand toothpaste, sauces Prevents precipitation of Food additive; food and Citric Acid metal oxides beverages, lemon juice Used to increase the Glass cleaner, Isopropanol viscosity of the fracture antiperspirant, hair coloring fluid Source: DOE, GWPC: Modern Gas Shale Development in the United States: A Primer (2009).

8 Technical challenges stimulation 1500. Well A. 1000. Well C. 500. More Monitor Well Well B. 0. South-North (ft). complex configuration? -500. Frac Well -1000. Well D. -1500. -2000. Well E. -2500. FRACTURE DIAGNOSTICS - MICROSEISMIC. -3000. -1000 -500 0 500 1000 1500 2000 2500 3000. Courtesy of Devon West-East (ft). Technical challenges stimulation Multi-Zone Stimulation 7100. Gamma Log Unequal Distribution Unequal Fracturing 7200 of Fracturing Activity Activity 7300. Depth (ft). Some Sands 7400. Unstimulated 7500. Depleted Sands May 7600. Side View Fracture Most 7700.

9 -400 -300 -200 -100 0 100 200 300 400. Distance Along Fracture (ft). FRACTURE DIAGNOSTICS - MICROSEISMIC. Lenticular Sandstone Case Technical challenges Gamma Ray 0 100 200. production performance 4500. How to acquire continuous, realtime, insitu monitoring of 5000. production, pressure data? 5500. 20 to 40 pay Intervals Depth (ft). over 3000 ft 6000. How to identify bypassed pay 6500. zones? How to stimulate multiple pay 7000. zones? 7500. Horizontal well Completions Technical challenges stimulation Technical challenges stimulation Example of MSG for multiple stages in a horizontal well