# Well Planning and Construction Haynesville Shale – East Texas Carolyn S. Debrick, PE Drilling Engineering Manager – Southern DivisionNYSE: DVN www.devonenergy.com page2 

# Agenda • Haynesville Shale • Well Planning – Design • Well Interference • Surface Casing Setting Depth • Casing Design Considerations • Surface Casing Cement Design • Production Casing Cement DesignNYSE: DVN www.devonenergy.com page 3 

# Haynesville Shale East Texas • Located in East Texas, Six Counties • Total Vertical Depth: 10,500’ to 13,600’ • Measured Depth: 15,500’ to 20,000’ • Pore Pressure: 15 ppg to 18 ppg • Shale Frac Gradient: > 1.0 psi/ft • Treatment Pressure > 10,000 psi • Bottom Hole Temperature: 270 to 350 FNYSE: DVN www.devonenergy.com page4 

# Well Planning - Design Pore Pressure, Frac Gradient, & Casing Seat Selections Leak Off Test data

Disposal Zones Depleted ZoneNYSE: DVN www.devonenergy.com page 5 

# Well Planning – Designs (cont.) Duck Creek Anhydrite Rodessa Pettit Travis Peak Cotton Valley Bossier Haynesville 2200

5000 5400 5900 6300 8000 9900 -12500 10500 -13600 9- 14 9 9– 13.8 2- 9 4 to 9.8 4 to 9.8 14- 17 14- 17 2000’ Knowles Lime and 11.5 to 12.5 ppg MW 1000’ 1500’ Stage Cement Tool Panola County 10,300’ TVD Harrison County

10,800’ Exploration, South

13,600’ TVD, 350 F Geologic Cross Section Formation Depth, ft MW, ppgNYSE: DVN www.devonenergy.com page 6 

# Well Interference: Anti-Collision • Directional planning off a pad • Different survey tools • Separation FactorNYSE: DVN www.devonenergy.com page 7 

# Surface Casing Setting Depth & MASP • Base of Wilcox, Panola County: 250 ft to 350 ft • Requirement is 200 ft or less below the base • Maximum Anticipated Surface Pressure – MASP • Devon sets surface casing at depth greater than prescribed by regulator to protect the USDW, the rig, and personnel • MASP = Fracture Gradient – maximum Mud Weight planned for next hole section Surface Casing Depth Fracture

EMW Planned Mud

Weight MASP 600 ft 11.5 ppg 10 ppg 47 psi 1,000 ft 12.5 ppg 10 ppg 130 psi 1,500 ft 13.5 ppg 10 ppg 234 psiNYSE: DVN www.devonenergy.com page 8 

# Casing Design Considerations • Loads
– Drilling
– Casing running loads
– Stimulation
– Production • Connection Selection
– Pressure application, API or premium
– Bending strength
– Need to rotate
– Compression and tension efficiency
– Surface casing connection – Wellhead load structural requirementsNYSE: DVN www.devonenergy.com page9 

# Surface Casing Cement • Class A Cement
– 15 ppg tail, 30% annular height
– Extenders & accelerators added to lead
– Cement returns to surface • Haynesville Field Practices
– Condition mud
– Keep ECD below fracture strength
– Pump spacers
– Run centralizers
– Reciprocate casing
– Test casing shoe after drilling out • Cement Design on Next String
– Top of cement (TOC) into shoe of surface casing
– Or, Run cement bond log (CBL) to determine if TOC is sufficiently above any zone to be stimulatedNYSE: DVN www.devonenergy.com page 10 

# Production Casing & Cement Haynesville Horizontal Well • Design concerns
– Close tolerance between hole & casing size
– High mud & cement weights; therefore more circulating friction • Haynesville Field Practices
– Run surge & swab to determine casing running speed
– Reduce mud yield point before tripping to run casing
– Design low rheology cement
– Run cement job ECD’s to determine cement displacement rates & ensure below fracture
– Run swell packer if job ECD & fracture strength close • If flow after cementing is a concern:
– Shut in annular
– Hold pressure & wait until cement sets
– Run a CBL before perforatingNYSE: DVN www.devonenergy.com page 11 

# Production Casing & Cement (cont.) Haynesville Horizontal Well Design Considerations: • Zero free water • Fluid loss below 150 cc • Adequate turbulent spacer • Expander • Gas Stop Example Tests: • Lab tests are performed on new slurry design to ensure they perform as designed – Example test.

# Thank You.