02 Casing Heads - Basis Of Casing Design.pdf
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Quartz School for Well Site Supervisors Module – 4 Casing Selection & Design
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Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
Section – 2 Casing Heads & Basis of Casing Design
Overview Introduction Casing Strings Conductor Surface Casing Intermediate Casing Production Casing Liner String
Casing Components Casing Design Classifications Pressures Size
• Steel Grade Selection 2/53
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
Introduction Casing is Steel Pipe that is run and secured in the wellbore The reasons for running casing include the following
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Support wellhead equipment and BOPs, Prevent mud contamination of water table at surface, Control influx from formation fluid, Seal off lost circulation zones, Keep hole open, Isolate producing zone.
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
Typical Casing Strings Exploration well
Development well
5 casings
4 casings
20” 20”
1313-3/8” 3/8”
9-5/8” 5/8”
7”
Conductor
20” 20”
Schlumberger Private
30” 30”
Surface casing
Intermediate
Intermediate
Production
1313-3/8” 3/8”
9-5/8” 5/8”
7”
Reservoir
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Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Casing Strings Schlumberger Private
5/53
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Conductor Pipe This is the first casing to be run when there is no drive pipe
30” - 20” Welded, 20” - 16” Threaded, 30’ - 200’ (< 100’ common).
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Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
to prevent washing out under the rig, Provides elevation for return flow to bell nipple, It is the string on which Diverter can be set, It is cemented to surface or seabed. It supports the wellhead and subsequent casing string and its setting is critical in terms of compressional loading and integrity of the cement, Common Sizes and Depths:
Surface Casing Protects fresh water aquifers, It is the first string on which BOP can be set to provide
20”- 16” - 13 3/8”- 9 5/8” 100’ - 3000’ (or more).
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Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
primary pressure control, It is cemented to surface or seabed, to case-off unconsolidated or lost circulation areas and support subsequent casing strings/ wellhead, Common sizes and depth:
Intermediate Casing Installed mainly to Separate hole into workable sections The number of intermediate strings set depends on: Fracture Pressure/Kick tolerance at last shoe, Proximity to a potential reservoir. (It is good practice to set
The casing is normally cemented meters above the shoe or to surface. It could be cemented in two stages as well, Common sizes and depths:
13 3/8”, 10 3/4”, 9 5/8”, 3000’ to 10,000’.
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Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
intermediate string above reservoir), Hole problems (i.e. lost circulation, salt section, differential sticking, caving, over pressured zones, heaving shale),
Production Casing Final string to be run in which production testing and
9/53
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
subsequent production will take place, The primary purpose is to isolate the production zones thus allowing proper control of the reservoir (artificial lift, multiple zone completion etc.), It can be full string from surface, a liner hung from the last intermediate casing or a liner that is tied back to the surface, Cementing is very important to prevent communication in the annulus, Covers worn or damaged intermediate string, Common sizes: 5 ½”, 7”, & 9 5/8”.
Liner Strings Casing string that does not extend to the top of the wellbore, but is anchored inside the bottom of the previous casing string Purpose:
salt zones. Rig unable to lift long string of casing in deep wells,
Types of Liners Production Liners: most commonly installed to save $$, Drilling Liners: Installed to cover problem zones or to cover worn-out casing in order to be able to continue drilling,
Common sizes: 4 ½”, 5”, 7”. 10/53
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
Mostly same as production casing, Cover lost circulation zones, shale or plastic formations, and
Liner Tie Back
11/53
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
TIE BACK
STINGER WITH SEALS Schlumberger Private
Tie-Back (Liner Complement): The integration of the liner with casing from top of existing liner to surface, To further up casing to cover corroded or damaged section of the existing casing, This is often done if production is commercially viable or there is damage to casing above the liner.
LINER
Casing Strings Summary
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Drive Pipe, Conductor Pipe, Surface Casing, Intermediate Casing, Production Casing: Liner, Liner & Tieback
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
Casing Components Schlumberger Private
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Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Cellar, Wellhead, Base Plate The casing head may be used in conjunction with a base plate for more effective weight distribution.
Wellhead Base Plate Conductor Pipe Surface Casing
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Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
Cellar
Wellhead Bottom Connection: Slip-on Weld bottom (as shown)
Slip Lock
15/53
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
Threaded bottom
Casing Head Spools Second element of the wellhead
Schlumberger Private
16/53
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Casing Spool Functions Seals off (packs off) surface casing
Connection
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Ring Groove
Schlumberger Private
Top Connection string Provides support (landing bowl) for next casing string provides support for well control equipment (BOP Stack) Casing Sealing the wellbore from the Landing Area atmosphere Controlling access to the wellbore : for pressure control or fluid returns during drilling operations. Bottom
Side Outlet
Test Port Casing Pack Off
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Casing Hangers
Landing area
Conductor pipe Surface casing
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Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
Intermediate casing
Functions Suspends intermediate or production casing string Centres the casing string in the head (or spool) Seals off the casing annulus
Slip Type Hanger Two major types of casing hangers
Slip type hanger (wraparound casing slips) Mandrel type hanger
Slip Bowl
Elastomer Seal Schlumberger Private
Support and Isolation
Prevent communication between casing strings Prevent flange seal from exposure to annular pressure
Wraparound Casing Slips with Sealing Capability
19/53
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Mandrel Type Hanger Two major types of casing hangers
Slip type hanger (wraparound
Support and Isolation
Prevent communication between casing strings Prevent flange seal from exposure to annular pressure
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Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
casing slips) Mandrel type hanger
Casing Design Schlumberger Private
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Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Casing Classifications Outside Diameter: This is the normal (nominal) diameter of the casing measured to the outside surface of the casing body, API permits a tolerance of + 0.75%.
It is the weight of the finished joint including couplings and upsets where appropriate per unit length, The nominal weight of the casing is expressed in either pounds per foot or kilograms per meter.
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Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
Weight:
Casing Classifications Wall Thickness: It is half of the difference between the nominal outside
Grade: The grade of a casing is designated by a letter and number combination (e.g. J55, C75, N80, P110), The number is the API minimum internal yield strength in thousands of psi, Hence, for example, J55 has a minimum yield strength of 55000 psi. 23/53
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
and inside diameters of the casing body with a tolerance of -12.5%, and related to weight and wall thickness, The drift diameter is used in sizing the drill bit.
Casing Design Considerations
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Determination of factors which influence failure Selection of the most suitable casing grades and weights Live of the well requirements A good knowledge of the stress analysis and the ability to apply it are necessary for the design of casing strings. Casing must be capable of withstanding the expected internal and external pressures ,axial loading and bending forces In general, the cost of a given casing grade is proportional to its weight, the heaviest weight being the most expensive,
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
Main Design Criteria – Collapse Pressure This pressure originates from the column of mud used to drill
Pressure
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Pressure
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
the hole and acts on the outside of the casing, Since the hydrostatic pressure of a column of mud increases with depth, collapse pressure is highest at the bottom and zero at top.
Basic Collapse Assumptions Casing is empty due to lost circulation at shoe or at TD,
is zero,
External pressure is caused by mud in which casing was run,
No cement outside casing.
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CSD
TD
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
Internal pressure inside casing
Main Design Criteria – Burst Pressure
The burst criterion is normally based on
Pressure
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Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
the maximum formation pressure resulting from a kick during the drilling of the next hole section.
Burst Pressure Gas to Surface – extreme case It is assumed that the influx fluid displaces the entire drilling mud, Casing subjected to bursting effects of formation pressure. Internal pressure must be supported entirely by the casing body, Burst pressure is highest at the top and lowest at the casing shoe where internal pressure is resisted by the external pressure due to fluids outside the casing,
Conventional casing design assumes a gas kick – worst case The gas gradient is in the order of 0.1 psi/ft. This gradient causes a small decrease in formation pressure as gas rises up the well,
In exploration wells, where reservoir pressure is not known, formation pressure from the next open hole section is calculated from the maximum mud weight. 28/53
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
Major Design Criteria – Burst Pressure 0.1 psi / ft Gas Gradient
4000 psi
0 psi
Schlumberger Private
Pressure
10,000 ft
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5000 psi
5000 psi
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Main Design Criteria – Tensile Load Most of axial tension arises from the weight of the casing
itself, Other tension loadings can arise due to:
In casing design, the uppermost joint of the string is considered the weakest in tension as it has to carry the total weight of the casing string.
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Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
Bending, Drag, Shock loading and during pressure testing of casing.
i-Handbook Electronic Schlumberger Handbook with Pipe data for both API standard and non-API tubulars Useful calculators to help with multiple well operations such
Download from http://www.hub.slb.com/index.cfm?id=id1384022
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Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
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as drilling and work over; cementing; fracturing; acid, oil and brines; and general unit conversions. Library of predefined wellbore diagrams Copy and paste features for exporting handbook data to other applications
API Steel Grade Applications: 1. The microstructure of steel and mechanical properties can
2. Thus, different grades of casing can be manufactured to suit different drilling situations.
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Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
be greatly changed by the addition of special alloys and by heat treatment.
API Steel Grade Applications: H-40
Used only for non-critical, shallow wells.
H-40 couplings must never be used since there is no API toughness requirement for them; use K-55 couplings instead.
This grade is the dumping ground for materials that were intended to be J-55 or K-55.
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Do not use for sour service applications.
API Steel Grade Applications: J-55
Fit for H2S service at all temperatures.
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Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
Often used for shallow tubing strings.
API Steel Grade Applications: K-55
Fit for H2S service at all temperatures. line pipe grades X-52 and X-56 are becoming a popular replacement.
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Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
Often used for large diameter surface casing strings, although
API Steel Grade Applications: M-65
Fit for H2S service at all temperatures.
Mostly produced as an EW grade and not used very much at this time.
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Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
New API grade (just released in April 99).
API Steel Grade Applications: L-80
Fit for H2S service at all temperatures.
An SSC (sulfide stress cracking) test is not required. Insist on hot rotary straightening when ordering this product. Often used for sour service production casing, production liners, and tubing.
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Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
Has a maximum hardness requirement.
API Steel Grade Applications: N-80
Fit for H2S service at temperatures greater than 150 ºF (beware Fit for H2S service at temperatures greater than 175 ºF (beware of future well cooling) if normalized (N) or normalized and tempered (N&T).
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Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
of future well cooling) if quenched and tempered (Q&T).
API Steel Grade Applications: C-90
A sour service grade fit for H2S service at all temperatures.
Has a maximum hardness requirement. Has a maximum through wall hardness variation requirement. Has a minimum as-quenched hardness (harden ability) requirement. An SSC test is required to demonstrate a minimum threshold stress of 80% of Yp. NACE method D (DCB) test is preferred. 39/53
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
Use only Type 1.
API Steel Grade Applications: C-90 (Continued)
This grade is becoming obsolete in favor of T-95. May be used
Effectively equivalent to 41XX.
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Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
for sour service production casing and production liners when L-80 does not have enough strength for the desired wall thickness.
API Steel Grade Applications: C-95
C-95 is not a sour service grade! of future well cooling).
Usually used for intermediate casing strings that may be exposed to H2S during a gas kick.
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Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
Fit for H2S service at temperatures greater than 150 ºF (beware
API Steel Grade Applications: T-95
A sour service grade fit for H2S service at all temperatures.
Has a maximum hardness requirement. Has a maximum through wall hardness variation requirement. Has a minimum as-quenched hardness (harden ability) requirement. An SSC test is required to demonstrate a minimum threshold stress of 80% of Yp. NACE Method D (DCB) is the preferred test.
42/53
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
Use only Type 1.
API Steel Grade Applications: T-95
Often used for HPHT sour gas production casing strings when
Very expensive.
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Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
L-80 and C-90 do not have enough strength for the desired wall thickness.
API Steel Grade Applications: P-110
Fit for H2S service at temperatures greater than 175 ºF (beware of future well cooling).
grade. Beware!
Insist on hot rotary straightening when ordering this product.
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Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
API has absolutely minimal chemistry requirements for this
API Steel Grade Applications: C-110 (Non API)
A proprietary sour service grade that may or may not be fit for Suitability depends on a number of factors including: the manufacturer, the pH of the produced fluids, and the partial pressure of H2S.
If used for sour service and pH of produced fluids is less than 4.0, this grade is not recommended.
Very expensive. 45/53
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
H2S service at all temperatures.
API Steel Grade Applications: Q-125
Fit for H2S service at temperatures greater than 225 ºF (beware
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Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
of future well cooling). Has a maximum through wall hardness variation. Often used for critical service wells.
API Steel Grade Applications: U-140 (Non API Grade)
Not suitable for sour service at any temperature. service.
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Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
May be very brittle and almost always not acceptable for OCTG
API Steel Grade Applications: V-150 (Non API Grade)
Not an API grade
Never use this grade!!!
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Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
Extremely brittle and never acceptable for OCTG service.
Corrosion Resistance Alloy Selection CRA provides the pipe the following properties:
Velocity Enhancement Higher Strength
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Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
Corrosion Resistance
Corrosion Resistance Alloy Selection Martensitic Stainless Steels (13Cr) pCO2 < 500 psi pH2S < 1.5 psi pH > 3.5 (no H2S resistance below this value) T < 300 °F (13Cr); T < 320 °F (13Cr-4Ni-1Mo) T < 340 °F (13Cr-5Ni-2Mo) T < 390 °F (15Cr-6Ni-2Mo-1Cu)
See Table A.19 in ISO15156
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Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
Corrosion Resistance Alloy Selection Duplex Stainless Steels (Cr22, Cr25) No limit on pCO2 pH2S < 1.5 psi T< 390 °F (Cr22); T < 480 °F (Cr25) Cl- < 120000 mg/l
See Table A.25 in ISO15156
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Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
Corrosion Resistance Alloy Selection High Alloy Austenitic Stainless Steels (2535, 2832) pCO2 < 1500 psi pH2S < 15 psi T < 340 °F Cl- < 5000 mg/l
See Table A.9 in ISO15156
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Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
Corrosion Resistance Alloy Selection Solid Solution Nickel-Based Alloys (825, 2550)
See Tables A.12 and A.14 in ISO15156
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Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
No limit on pCO2 pH2S < 1000 psi T < 450 °F
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Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
Section – 2 Casing Heads & Basis of Casing Design
Overview Introduction Casing Strings Conductor Surface Casing Intermediate Casing Production Casing Liner String
Casing Components Casing Design Classifications Pressures Size
• Steel Grade Selection 2/53
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
Introduction Casing is Steel Pipe that is run and secured in the wellbore The reasons for running casing include the following
3/53
Support wellhead equipment and BOPs, Prevent mud contamination of water table at surface, Control influx from formation fluid, Seal off lost circulation zones, Keep hole open, Isolate producing zone.
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
Typical Casing Strings Exploration well
Development well
5 casings
4 casings
20” 20”
1313-3/8” 3/8”
9-5/8” 5/8”
7”
Conductor
20” 20”
Schlumberger Private
30” 30”
Surface casing
Intermediate
Intermediate
Production
1313-3/8” 3/8”
9-5/8” 5/8”
7”
Reservoir
4/53
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Casing Strings Schlumberger Private
5/53
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Conductor Pipe This is the first casing to be run when there is no drive pipe
30” - 20” Welded, 20” - 16” Threaded, 30’ - 200’ (< 100’ common).
6/53
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
to prevent washing out under the rig, Provides elevation for return flow to bell nipple, It is the string on which Diverter can be set, It is cemented to surface or seabed. It supports the wellhead and subsequent casing string and its setting is critical in terms of compressional loading and integrity of the cement, Common Sizes and Depths:
Surface Casing Protects fresh water aquifers, It is the first string on which BOP can be set to provide
20”- 16” - 13 3/8”- 9 5/8” 100’ - 3000’ (or more).
7/53
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
primary pressure control, It is cemented to surface or seabed, to case-off unconsolidated or lost circulation areas and support subsequent casing strings/ wellhead, Common sizes and depth:
Intermediate Casing Installed mainly to Separate hole into workable sections The number of intermediate strings set depends on: Fracture Pressure/Kick tolerance at last shoe, Proximity to a potential reservoir. (It is good practice to set
The casing is normally cemented meters above the shoe or to surface. It could be cemented in two stages as well, Common sizes and depths:
13 3/8”, 10 3/4”, 9 5/8”, 3000’ to 10,000’.
8/53
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
intermediate string above reservoir), Hole problems (i.e. lost circulation, salt section, differential sticking, caving, over pressured zones, heaving shale),
Production Casing Final string to be run in which production testing and
9/53
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
subsequent production will take place, The primary purpose is to isolate the production zones thus allowing proper control of the reservoir (artificial lift, multiple zone completion etc.), It can be full string from surface, a liner hung from the last intermediate casing or a liner that is tied back to the surface, Cementing is very important to prevent communication in the annulus, Covers worn or damaged intermediate string, Common sizes: 5 ½”, 7”, & 9 5/8”.
Liner Strings Casing string that does not extend to the top of the wellbore, but is anchored inside the bottom of the previous casing string Purpose:
salt zones. Rig unable to lift long string of casing in deep wells,
Types of Liners Production Liners: most commonly installed to save $$, Drilling Liners: Installed to cover problem zones or to cover worn-out casing in order to be able to continue drilling,
Common sizes: 4 ½”, 5”, 7”. 10/53
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
Mostly same as production casing, Cover lost circulation zones, shale or plastic formations, and
Liner Tie Back
11/53
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
TIE BACK
STINGER WITH SEALS Schlumberger Private
Tie-Back (Liner Complement): The integration of the liner with casing from top of existing liner to surface, To further up casing to cover corroded or damaged section of the existing casing, This is often done if production is commercially viable or there is damage to casing above the liner.
LINER
Casing Strings Summary
12/53
Drive Pipe, Conductor Pipe, Surface Casing, Intermediate Casing, Production Casing: Liner, Liner & Tieback
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
Casing Components Schlumberger Private
13/53
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Cellar, Wellhead, Base Plate The casing head may be used in conjunction with a base plate for more effective weight distribution.
Wellhead Base Plate Conductor Pipe Surface Casing
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Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
Cellar
Wellhead Bottom Connection: Slip-on Weld bottom (as shown)
Slip Lock
15/53
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
Threaded bottom
Casing Head Spools Second element of the wellhead
Schlumberger Private
16/53
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Casing Spool Functions Seals off (packs off) surface casing
Connection
17/53
Ring Groove
Schlumberger Private
Top Connection string Provides support (landing bowl) for next casing string provides support for well control equipment (BOP Stack) Casing Sealing the wellbore from the Landing Area atmosphere Controlling access to the wellbore : for pressure control or fluid returns during drilling operations. Bottom
Side Outlet
Test Port Casing Pack Off
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Casing Hangers
Landing area
Conductor pipe Surface casing
18/53
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
Intermediate casing
Functions Suspends intermediate or production casing string Centres the casing string in the head (or spool) Seals off the casing annulus
Slip Type Hanger Two major types of casing hangers
Slip type hanger (wraparound casing slips) Mandrel type hanger
Slip Bowl
Elastomer Seal Schlumberger Private
Support and Isolation
Prevent communication between casing strings Prevent flange seal from exposure to annular pressure
Wraparound Casing Slips with Sealing Capability
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Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Mandrel Type Hanger Two major types of casing hangers
Slip type hanger (wraparound
Support and Isolation
Prevent communication between casing strings Prevent flange seal from exposure to annular pressure
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Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
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casing slips) Mandrel type hanger
Casing Design Schlumberger Private
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Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Casing Classifications Outside Diameter: This is the normal (nominal) diameter of the casing measured to the outside surface of the casing body, API permits a tolerance of + 0.75%.
It is the weight of the finished joint including couplings and upsets where appropriate per unit length, The nominal weight of the casing is expressed in either pounds per foot or kilograms per meter.
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Weight:
Casing Classifications Wall Thickness: It is half of the difference between the nominal outside
Grade: The grade of a casing is designated by a letter and number combination (e.g. J55, C75, N80, P110), The number is the API minimum internal yield strength in thousands of psi, Hence, for example, J55 has a minimum yield strength of 55000 psi. 23/53
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and inside diameters of the casing body with a tolerance of -12.5%, and related to weight and wall thickness, The drift diameter is used in sizing the drill bit.
Casing Design Considerations
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Determination of factors which influence failure Selection of the most suitable casing grades and weights Live of the well requirements A good knowledge of the stress analysis and the ability to apply it are necessary for the design of casing strings. Casing must be capable of withstanding the expected internal and external pressures ,axial loading and bending forces In general, the cost of a given casing grade is proportional to its weight, the heaviest weight being the most expensive,
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
Main Design Criteria – Collapse Pressure This pressure originates from the column of mud used to drill
Pressure
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Pressure
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
the hole and acts on the outside of the casing, Since the hydrostatic pressure of a column of mud increases with depth, collapse pressure is highest at the bottom and zero at top.
Basic Collapse Assumptions Casing is empty due to lost circulation at shoe or at TD,
is zero,
External pressure is caused by mud in which casing was run,
No cement outside casing.
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CSD
TD
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
Internal pressure inside casing
Main Design Criteria – Burst Pressure
The burst criterion is normally based on
Pressure
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Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
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the maximum formation pressure resulting from a kick during the drilling of the next hole section.
Burst Pressure Gas to Surface – extreme case It is assumed that the influx fluid displaces the entire drilling mud, Casing subjected to bursting effects of formation pressure. Internal pressure must be supported entirely by the casing body, Burst pressure is highest at the top and lowest at the casing shoe where internal pressure is resisted by the external pressure due to fluids outside the casing,
Conventional casing design assumes a gas kick – worst case The gas gradient is in the order of 0.1 psi/ft. This gradient causes a small decrease in formation pressure as gas rises up the well,
In exploration wells, where reservoir pressure is not known, formation pressure from the next open hole section is calculated from the maximum mud weight. 28/53
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
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Major Design Criteria – Burst Pressure 0.1 psi / ft Gas Gradient
4000 psi
0 psi
Schlumberger Private
Pressure
10,000 ft
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5000 psi
5000 psi
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Main Design Criteria – Tensile Load Most of axial tension arises from the weight of the casing
itself, Other tension loadings can arise due to:
In casing design, the uppermost joint of the string is considered the weakest in tension as it has to carry the total weight of the casing string.
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Bending, Drag, Shock loading and during pressure testing of casing.
i-Handbook Electronic Schlumberger Handbook with Pipe data for both API standard and non-API tubulars Useful calculators to help with multiple well operations such
Download from http://www.hub.slb.com/index.cfm?id=id1384022
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as drilling and work over; cementing; fracturing; acid, oil and brines; and general unit conversions. Library of predefined wellbore diagrams Copy and paste features for exporting handbook data to other applications
API Steel Grade Applications: 1. The microstructure of steel and mechanical properties can
2. Thus, different grades of casing can be manufactured to suit different drilling situations.
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be greatly changed by the addition of special alloys and by heat treatment.
API Steel Grade Applications: H-40
Used only for non-critical, shallow wells.
H-40 couplings must never be used since there is no API toughness requirement for them; use K-55 couplings instead.
This grade is the dumping ground for materials that were intended to be J-55 or K-55.
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Do not use for sour service applications.
API Steel Grade Applications: J-55
Fit for H2S service at all temperatures.
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Often used for shallow tubing strings.
API Steel Grade Applications: K-55
Fit for H2S service at all temperatures. line pipe grades X-52 and X-56 are becoming a popular replacement.
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Often used for large diameter surface casing strings, although
API Steel Grade Applications: M-65
Fit for H2S service at all temperatures.
Mostly produced as an EW grade and not used very much at this time.
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New API grade (just released in April 99).
API Steel Grade Applications: L-80
Fit for H2S service at all temperatures.
An SSC (sulfide stress cracking) test is not required. Insist on hot rotary straightening when ordering this product. Often used for sour service production casing, production liners, and tubing.
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Has a maximum hardness requirement.
API Steel Grade Applications: N-80
Fit for H2S service at temperatures greater than 150 ºF (beware Fit for H2S service at temperatures greater than 175 ºF (beware of future well cooling) if normalized (N) or normalized and tempered (N&T).
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of future well cooling) if quenched and tempered (Q&T).
API Steel Grade Applications: C-90
A sour service grade fit for H2S service at all temperatures.
Has a maximum hardness requirement. Has a maximum through wall hardness variation requirement. Has a minimum as-quenched hardness (harden ability) requirement. An SSC test is required to demonstrate a minimum threshold stress of 80% of Yp. NACE method D (DCB) test is preferred. 39/53
Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
Use only Type 1.
API Steel Grade Applications: C-90 (Continued)
This grade is becoming obsolete in favor of T-95. May be used
Effectively equivalent to 41XX.
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for sour service production casing and production liners when L-80 does not have enough strength for the desired wall thickness.
API Steel Grade Applications: C-95
C-95 is not a sour service grade! of future well cooling).
Usually used for intermediate casing strings that may be exposed to H2S during a gas kick.
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Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
Schlumberger Private
Fit for H2S service at temperatures greater than 150 ºF (beware
API Steel Grade Applications: T-95
A sour service grade fit for H2S service at all temperatures.
Has a maximum hardness requirement. Has a maximum through wall hardness variation requirement. Has a minimum as-quenched hardness (harden ability) requirement. An SSC test is required to demonstrate a minimum threshold stress of 80% of Yp. NACE Method D (DCB) is the preferred test.
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Use only Type 1.
API Steel Grade Applications: T-95
Often used for HPHT sour gas production casing strings when
Very expensive.
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Quartz School. Module 4: Casing Selection & Design / Section 2: Csng. Heads & Basis of Casing Design
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L-80 and C-90 do not have enough strength for the desired wall thickness.
API Steel Grade Applications: P-110
Fit for H2S service at temperatures greater than 175 ºF (beware of future well cooling).
grade. Beware!
Insist on hot rotary straightening when ordering this product.
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API has absolutely minimal chemistry requirements for this
API Steel Grade Applications: C-110 (Non API)
A proprietary sour service grade that may or may not be fit for Suitability depends on a number of factors including: the manufacturer, the pH of the produced fluids, and the partial pressure of H2S.
If used for sour service and pH of produced fluids is less than 4.0, this grade is not recommended.
Very expensive. 45/53
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H2S service at all temperatures.
API Steel Grade Applications: Q-125
Fit for H2S service at temperatures greater than 225 ºF (beware
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of future well cooling). Has a maximum through wall hardness variation. Often used for critical service wells.
API Steel Grade Applications: U-140 (Non API Grade)
Not suitable for sour service at any temperature. service.
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May be very brittle and almost always not acceptable for OCTG
API Steel Grade Applications: V-150 (Non API Grade)
Not an API grade
Never use this grade!!!
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Extremely brittle and never acceptable for OCTG service.
Corrosion Resistance Alloy Selection CRA provides the pipe the following properties:
Velocity Enhancement Higher Strength
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Corrosion Resistance
Corrosion Resistance Alloy Selection Martensitic Stainless Steels (13Cr) pCO2 < 500 psi pH2S < 1.5 psi pH > 3.5 (no H2S resistance below this value) T < 300 °F (13Cr); T < 320 °F (13Cr-4Ni-1Mo) T < 340 °F (13Cr-5Ni-2Mo) T < 390 °F (15Cr-6Ni-2Mo-1Cu)
See Table A.19 in ISO15156
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Corrosion Resistance Alloy Selection Duplex Stainless Steels (Cr22, Cr25) No limit on pCO2 pH2S < 1.5 psi T< 390 °F (Cr22); T < 480 °F (Cr25) Cl- < 120000 mg/l
See Table A.25 in ISO15156
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Corrosion Resistance Alloy Selection High Alloy Austenitic Stainless Steels (2535, 2832) pCO2 < 1500 psi pH2S < 15 psi T < 340 °F Cl- < 5000 mg/l
See Table A.9 in ISO15156
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Corrosion Resistance Alloy Selection Solid Solution Nickel-Based Alloys (825, 2550)
See Tables A.12 and A.14 in ISO15156
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No limit on pCO2 pH2S < 1000 psi T < 450 °F
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