Factors Affecting Casing Design

 "I do not think there should be a limit on the rig's liability, because they are sitting on top of unlimited amounts of oil, and thus, there could be an explosion occur that could do untold damage. ... The amount of damage that an offshore oil rig can do is infinite." 

- John Chafee,1989

T.D Hewavitharana080812M

politicalhumor.about.comStar tribune Sack(2010).

politicalhumor.about.comStar tribune Sack(2010).

politicalhumor.about.comBennet(2010).

Deepwater Horizon Study Group March 1, 201, Final Report on the Investigation of the    Macondo Well Blowout.

Maryann Tobin (2010). Experts agree BP oil well casing has failed: Relief wells may not stop Deepwater Horizon oil leak. [ONLINE] Available at: Deepwater Horizon Study Group March 1, 201, Final Report on the Investigation of the    Macondo Well Blowou. . [Last Accessed e.g. 31 August 11].

Content

• Design Factors• Relationship Between the Factors• Comparison of Factors with Depth• Casing Design• API Design (Safety) Factors

Collapse, Burst and Tension

Collapse Failure

Burst Failure

Collapse, Burst, Tension RelationshipsBurst Resistance

Collapse Resistance

Co

mp

res

sio

n Ten

sion

X

y

80% from Tension free

condition

110% from Tension free

condition

R.G Turley, “Casing Design Dome Drlg Manual.pdf.”

Comparison with Depth

Dep

th

Stress

Collapse

Tension

Burst

Collapse

Tension

Bur

st

TD TD

TD - Total Depth

Casing Design

Worst Possible ConditionsFor Collapse design, assume that the casing is empty on the inside (p = 0 psi)

For Burst design, assume no “backup” fluid on the outside of the casing (p = 0 psi)

For Tension design, assume no buoyancy effect

For Collapse design, assume no buoyancy effect

Casing Designing Continued.

Required

10,000 psi

100,000 lbf

10,000 psi

1.125

1.8

1.1

Design

11,250 psi

180,000 lbf

11,000 psi

API Design (Safety) Factors

• Collapse

• Tension

• Burst

Why Safety Factor

Abnormal

References

• Rahman, S. S., & Chilingar, G. V. (1995). Casing design: theory and practice. Elsevier.

• Bellarby, J. (2009). Well Completion Design. Elsevier.• Rabia, H. (2001). Well engineering and construction.Entec.• Economides, M. J., Watters, L. T., & Dunn-Norman, S. (1998). Petroleum Well

Construction. Wiley.• Senate Floor Debate, 135 Cong. Rec. S9689-S9716 (3 Aug 1989). Reproduced in

Russell V. Randle, Oil Pollution Deskbook (1991), 432. • Star tribune Sack(2010). BP Damage Claims. [ONLINE] Available at:

http://politicalhumor.about.com/od/politicalcartoons/ig/Oil-Spill-Cartoons/BP-Damage-Claims.1-Tp.htm. [Last Accessed 13 March 12].

• ENI S.p.A. Agip Division, “Casing Design Manual.”• BG Group, “Casing Design Manual.”• Rock-Well Consultants, Casing Design – Review of Design Methodology.

Thank You.