ENGR 482 Lecture 10

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Lecture Slides

The role of the Industry Exemption in the Macondo Blowout and Oil Spill

Apr 20, 2010 Killed 11 men Released 5M barrels of oil into the Gulf of Mexico

Engineering Design process

Identify problem/need and constraints
Identify possible solutions
Develop conceptual designs
Model and test them
Develop engineering design requirements
Develop detailed engineering design and specifications
Model and test final engineering design
Construction or manufacture

Construction controls and inspection points to ensure that final product meets specifications

Cementing the Well Casing

Let's Analyze one task relevant to the blowout

Purpose? Keeps hydrocarbons locked in place when rig is uncoupled
Design process applied to cementing design
Process apparently used in cementing design
Personnel involved in design decisions
How industry exemption might have been a factor in this failure.

Problem

Need to isolate the pressurized pay sands' from well-bore and from the annulus so drilling mud/lubricant/coolant can be removed and the well can be shut in.

In lay terms, put a cork in the hole in the bottom of the sea so gases don't escape.

Preliminary and design

Select casing design and location and extent of cement

Based on modeling calculations, final design geometry and material property specifications are developed.

This design is modeled and tested

Actual Design

Approved final design was a long string casing and not the original.

There was a significant change in design while the well was being capped.

Modeling indicated that 21 centralizers were required to make sure drill is centered in the bore, but only 6 were available. Numerical modeling indicated that this would have a high risk for failure.

15 more were delivered, but they were the wrong type. Team leadership decided to go ahead with 6.

There were several difficulties encountered along the way, including:

cement not strong enough
bore was not adequately cleaned
didn't know if valves had been converted to one for cementing.
Many tests were skipped, and some tests were not performed correctly

Decision Makers

None were licensed in Texas, some didn't have a degree

Brian Morel: determined (mistakenly) that 15 additional centralizers were of cnventional design with separate stop collars

John Guide: rejected use of 15 additional centralizers and decided to use only the 6 on hand; wrote decision tree that led to decision that cement bond logs were not needed.

Industry Exemption

Why exemption may have been a factor

Licensed engineers are sure to have adequate experience
Engineers do not absorb non-engineering culture from surrounding positions (e.g. management)
Licensed engineers are required to have competence in their field
Licensed engineers are aware of their ethical responsibility to the public
There is an incentive for professional engineers to adhere to their professionalism (otherwise license can be revoked)

BP's corporate culture remained one embedded in risk-taking and cost-cutting