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Chapter 3 Casing design. What is casing?. Casing. Casing Design. Cement. Why run casing? 1 . To prevent the hole from caving in 2 . Onshore - to prevent contamination of fresh water sands 3 . To prevent water migration to producing formation. Casing Design .
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What is casing? Casing Casing Design Cement Why run casing? 1. To prevent the hole from caving in 2. Onshore - to prevent contamination of fresh water sands 3. To prevent water migration to producing formation
Casing Design 4. To confine production to the wellbore 5. To control pressures during drilling 6. To provide an acceptable environment for subsurface equipment in producing wells 7. To enhance the probability of drilling to total depth (TD) e.g., you need 14 ppg mud to control a lower zone, but an upper zone will fracture at 12 lb/gal. What do you do?
Diameter Example 16”-60” 30” 16”-48” 20” 8 5/8”-20” 13 3/8” Types of Strings of Casing 1. Drive pipe or structural pile {Gulf Coast and offshore only} 150’-300’ below mudline. 2. Conductor string. 100’ - 1,600’ (BML) 3. Surface pipe. 2,000’ - 4,000’ (BML)
Diameter Example Types of Strings of Casing 7 5/8”-13 3/8” 9 5/8” 4 1/2”-9 5/8” 7” 4. Intermediate String 5. Production String (Csg.) 6. Liner(s) 7. Tubing String(s)
Hole Size Pipe Size 36” 26” 17 1/2 12 1/4 8 3/4 Structural casing Conductor string Surface pipe IntermediateString Production Liner 30” 20” 13 3/8 9 5/8 7 Example Hole and String Sizes (in)