Casing Design for Extreme Temperature Matthas Matthasson and - - PowerPoint PPT Presentation

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Casing Design for Extreme Temperature Matthas Matthasson and Kristinn Ingason Basic assumptions The hole will be cased off down to the critical point Bottom Hole Temperature max 550 C Bottom Hole Pressure max 26,7 MPa

SLIDE 1

Casing Design for Extreme Temperature

Matthías Matthíasson and Kristinn Ingason

SLIDE 2

July 3, 2007: Engine

Basic assumptions

 The hole will be cased off down to the critical

point

 Bottom Hole Temperature max 550 C  Bottom Hole Pressure max 26,7 MPa  ASME and ASA codes or standards has to be

“intertwine” into API standards

 The well shall be “safe” in flowing and closed

conditions

SLIDE 3

July 3, 2007: Engine

Critical Point (CP)

CP represents the highest temperature and pressure at which the substance can exist as a vapour and liquid in equilibrium. CP for water: TC = 374 °C PC = 22,1 MPa

CP

SLIDE 4

July 3, 2007: Engine

Temperature and pressure assumptions above CP

 Boiling point curve to CP (3400 – 3500 m)  Hydrostatic conditions to CP

below CP

 Temperature will increase by 100 °C/km

 Constant density with depth (Icochor)

SLIDE 5

July 3, 2007: Engine

Reservoir temperature and pressure Static and Flowing

18000 16000 14000 12000 10000 8000 6000 4000 2000 1000 2000 3000 4000 5000 6000 7000 8000 100 200 300 400 500 600 700 800 900 10001100 6000 5000 4000 3000 2000 1000 10 20 30 40 50 60

Boiling water 20°C water Boiling water

Depth [m / feet] Pressure [MPa / psi] Temperature Pressure

100 200 300 400 500 600

Temperature [°C / °F]

6000 5000 4000 3000 2000 1000 10 20 30 40 50 60

Flowing well 550°C, 25 MPa, 9" pipe Flowing well, isochor, 9" pipe Boiling water 20°C wate

Depth [m] Pressure [MPa]

Pressure Temperature 100 200 300 400 500 600

Temperature [°C]

SLIDE 6

July 3, 2007: Engine

Design conditions

 Basic parameters at wellhead

 Flowing well: T= 500°C and P= 19,5 MPa

(Linear)

T= 340°C and P= 14,5 MPa

(Isochor)

 Closed well: T= 400°C and P= 22 MPa T= 20°C and P= 26.7 MPa

SLIDE 7

July 3, 2007: Engine

Well Design

SLIDE 8

July 3, 2007: Engine

Conclusions

Diameter:



ø13 5/8”, 88,2 lbs/ft for top 300 m of anchor casing



ø13 3/8”, 72,0 lbs/ft for 300 to 2400 m of anchor casing



Ø9 5/8”, 53,5 lbs/ft production casing

Casing materials:



T-95 type 1 and K-55 for anchor casing



K-55 for production casing

Casing connections:



Hydril 563 (coupling and thread)

Wellhead flange:



ø10” ANSI, Class 2500 (material group 1.9, ANSI B16.5)

Wellhead master vale:



ø10” ANSI, Class 2500 (material group 1.9, ANSI B16.34)

SLIDE 9

July 3, 2007: Engine

Stress Calculations

axially σz; tangentially σt; radially

,

r p m z

A A P

t m i

P D t 2 ,

r m

P 2 , Internal overpressure Pm (MPa) Internal pipe area Ap, (mm2) Cross-sectional area of pipe wall Ar (mm2) Internal pipe diameter Di (mm) Pipe wall thickness t (mm).

SLIDE 10

July 3, 2007: Engine

Stress Intensity

Permissible stress levels: S1 =

z - t ; S2 =

t r ; S3 = r

z

stress intensity S S = max(S1,S2,S3)

SLIDE 11

July 3, 2007: Engine

Allowable Stress

defined by the equation:

T T T Y Y Y m

R S S R S S S 3 1 , 1 , 3 1 , 3 2 , 3 2 min SY = minimum yield strength at room temperature ST = minimum tensile strength at room temperature RY and RT are the ratios of minimum yield strength and minimum tensile strength at working temperature to room temperature respectively. Material

Max. permitted stress intensity at prevailing temp

S < Sm

Stress Intensity < Allowable Stress

SLIDE 12

July 3, 2007: Engine

Casing material at elevated temperature

(Thomas 1967, Snyder 1979)

SLIDE 13

July 3, 2007: Engine

Elastic limit vs. temperature

(Maruyama 1990)

SLIDE 14

July 3, 2007: Engine

Tensile stress/strain curves

(Maruyama 1990)

SLIDE 15

July 3, 2007: Engine 100 200 300 400 500 600 700 50 100 150 200 250 300 350 400 450

500°C/195bar 400°C/220bar Material Group No. 1.2 Material Group No. 1.9 20°C/267bar

Class 2500

Material Group No. 1.2

Class 1500

Boiling Water

Working Pressure bar Temperature °C

PIPE FLANGES, ANSI B16.5

Material Group No. 1.2 (A216-WCC) 1.9 (A217-WC6)

Material Group No. 1.9 340°C/145bar

ANSI B16.34 Wellhead master valve selection criteria

SLIDE 16

July 3, 2007: Engine

HYDRIL connections, type 563

SLIDE 17

July 3, 2007: Engine

Final Points

 Information on casing material at

temperature higher than 350 C are scarce

 K55 appears to be the best suitable material  Creep resistant material is needed for top

part of anchor casing API T95

 Premium connection are essential HYDRIL

563

 Stress relaxation for K55 and L80 can be

expected for temperature as low as 250 C

 Thermal cycling should be kept to minimum

SLIDE 18

July 3, 2007: Engine

VGK-Hönnun hf. Grensásvegur 1, 108 Reykjavik, Tel: (+354) 422 3000 Web: www.vgkhonnun.is / E-mail: vgkhonnun@vgkhonnun.is