mr. bentum casin
TRANSCRIPT
7/27/2019 Mr. Bentum CASIN
http://slidepdf.com/reader/full/mr-bentum-casin 1/19
1
Cas in g Des ign
1.8-1
7/27/2019 Mr. Bentum CASIN
http://slidepdf.com/reader/full/mr-bentum-casin 2/19
2
1.8-2 Casing Design
Why Run Casing?Types of Casing Strings
Classification of CasingBurst, Collapse and TensionEffect of Axial Tension on Collapse Strength
7/27/2019 Mr. Bentum CASIN
http://slidepdf.com/reader/full/mr-bentum-casin 3/19
3
1.8-3 Casing Design
Why run casing?
1. To prevent the hole from caving in
2. Onshore - to prevent contamination of
fresh water sands3. To prevent water migration to
producing formation
What is casing? Casing
Cement
7/27/2019 Mr. Bentum CASIN
http://slidepdf.com/reader/full/mr-bentum-casin 4/19
4
1.8-4 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?
7/27/2019 Mr. Bentum CASIN
http://slidepdf.com/reader/full/mr-bentum-casin 5/19
5
1.8-5 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
16”-60” 30”
16”-48” 20”
8 5/8” -20” 13 3/8”
7/27/2019 Mr. Bentum CASIN
http://slidepdf.com/reader/full/mr-bentum-casin 6/19
6
1.8-6 Types of Strings of Casing
4. Intermediate String
5. Production String (Csg.)
6. Liner(s)
7. Tubing String(s)
7 5/8” -13 3/8” 9 5/8”
Diameter Example
4 1/2” -9 5/8” 7”
7/27/2019 Mr. Bentum CASIN
http://slidepdf.com/reader/full/mr-bentum-casin 7/19
7
1.8-7 Example Hole and String Sizes (in)
Structural casing
Conductor string
Surface pipe
IntermediateString
Production Liner
Hole Size30” 20”
13 3/8
9 5/8
7
Pipe Size 36” 26”
17 1/2
12 1/4
8 3/4
7/27/2019 Mr. Bentum CASIN
http://slidepdf.com/reader/full/mr-bentum-casin 8/19
8
1.8-8 Classification of CSG.
1. Outside diameter of pipe (e.g. 9 5/8”)
2. Wall thickness (e.g. 1/2”)
3. Grade of material (e.g. N-80)
4. Type to threads and couplings (e.g. API LCSG)
5. Length of each joint (RANGE) (e.g. Range 3)
6. Nominal weight (Avg. wt/ft incl. Wt. Coupling)
(e.g. 47 lb/ft)
7/27/2019 Mr. Bentum CASIN
http://slidepdf.com/reader/full/mr-bentum-casin 9/19
9
s e
1.8-9
7/27/2019 Mr. Bentum CASIN
http://slidepdf.com/reader/full/mr-bentum-casin 10/19
10
1.8-10 Casing Threads and Couplings
API round threads - short { CSG }
API round thread - long { LCSG }
Buttress { BCSG }
Extreme line { XCSG }
Other …
See Halliburton Book...
7/27/2019 Mr. Bentum CASIN
http://slidepdf.com/reader/full/mr-bentum-casin 11/19
11
Burst, Collapse, and Tension
1.9-1
7/27/2019 Mr. Bentum CASIN
http://slidepdf.com/reader/full/mr-bentum-casin 12/19
12
1.9-2 API Design Factors (typical)
Collapse 1.125
Tension 1.8
Burst 1.1
Required
10,000 psi
100,000 lbf
10,000 psi
Design
11,250 psi
180,000 lbf
11,000 psi
7/27/2019 Mr. Bentum CASIN
http://slidepdf.com/reader/full/mr-bentum-casin 13/19
13
Normal Pore Pressure Abnormal Pore Pressure 0.433 - 0.465 psi/ft g
p> normal
Abnormal1.9-3
7/27/2019 Mr. Bentum CASIN
http://slidepdf.com/reader/full/mr-bentum-casin 14/19
14
1.9-4 Casing Design
Burst: Assume full reservoir pressure all along the wellbore.Collapse: Hydrostatic pressure increases with depthTension: Tensile stress due to weight of string is highest at top
STRESS
Tension
Burst
Collapse
Collapse
Tension
Depth
Burst
7/27/2019 Mr. Bentum CASIN
http://slidepdf.com/reader/full/mr-bentum-casin 15/19
15
1.9-5 Casing Design
Unless otherwise specified in a particular problem, we shall also assume the following:
Worst Possible Conditions1. For Collapse design, assume that thecasing is empty on the inside (p = 0 psig)
2. For Burst design, assume no “backup”fluid on the outside of the casing (p = 0 psig)
7/27/2019 Mr. Bentum CASIN
http://slidepdf.com/reader/full/mr-bentum-casin 16/19
16
1.9-6 Casing Design
Worst Possible Conditions, cont’d 3. For Tension design,
assume no buoyancy effect
4. For Collapse design,assume no buoyancy effect
The casing string must be designed to stand up to theexpected conditions in burst, collapse and tension .Above conditions are quite conservative. They are alsosimplified for easier understanding of the basic concepts.
7/27/2019 Mr. Bentum CASIN
http://slidepdf.com/reader/full/mr-bentum-casin 17/19
17
1.9-7 Casing Design - Solution
Burst Requirements (based on the expected porepressure)
The whole casing string must be capable of withstanding this internal pressure without failing inburst.
psi600,6P
1.1* psi000,6
Factor Design* pressure poreP
B
B
D e p
t h
Pressure
7/27/2019 Mr. Bentum CASIN
http://slidepdf.com/reader/full/mr-bentum-casin 18/19
18
1.9-8 Casing Design - Solution
Collapse RequirementsFor collapse design, we start at the bottom of the string and work our way up.
7/27/2019 Mr. Bentum CASIN
http://slidepdf.com/reader/full/mr-bentum-casin 19/19
19
1.9-9 Tension Check
The weight on the top joint of casingwould be
With a design factor of 1.8 for tension, apipe strength of
weightactual602,386
)/#5.53*631,1()/#0.47*369,6(
lbs
ft ft ft ft
requiredislbf 080,695602,386*8.1