Deepwater Horizon – Another View
Harold S. Reemsnyder, PhD, PE, CEng, FWeldI
On 20-22 April 2010, a hydrocarbon explosion and subsequent fire aboard the semi-
submersible mobile offshore drilling unit (MODU), Deepwater Horizon sank the rig,
killed 11 and injured 17 workers of the 126 crew aboard. Thus began an enormous oil
spill in the Gulf of Mexico called, in the media, the largest in US history. The leak was
successfully shut-in on 4 August 2010 by a "static kill" (injection of heavy fluids into the
Previously, in September 2009, Deepwater Horizon drilled, on the Tiber oilfield, the
deepest oil well ever drilled with a total depth of 10,685 m (35,055 feet), in 1,259 m
(4,132 feet) of water. When the Deepwater Horizon was lost, she was completing a
well 60 km (40 miles) southeast of Louisiana in the Macondo Prospect oil field, 300
miles east of the Tiber site.
The Rig
Deepwater Horizon, chartered to BP through September 2013, was a dynamically
positioned, semi-submersible mobile offshore drilling unit (or MODU).
She was built by Hyundai Heavy Industries, Ulsan, Korea, 2000 – 2001 and delivered to
the owner in 2001 at a cost of $350 million. Classed by the American Bureau of
Shipping (ABS), she was flagged in Republic of Marshall Islands Registry. Her
particulars are listed below in Table 1, and parties involved are listed in Table 2.
Table 1. Deepwater Horizon – Particulars
Rated Water Depth: 3,048 m (10,000 ft)
Drilling Depth: 9,144 m (30,000 ft)
Gross Registered Tonnage: 32,588
Net Registered Tonnage: 9,776
Displacement: 52,587 tonnes (51,757 tons)
Length: 121 m (396 ft)
Beam: 78 m (256 ft)
Height: 97 m (320 ft)
Operating Draught: 23 m (76 ft)
Propulsion: Eight 7,375 hp, fixed propeller, full 360° azimuth, thrusters.
Table 2. Deepwater Horizon – Parties Involved
Registered Owner: Triton Asset Leasing GMBH, Switzerland.
Contract Operator: Transocean Holdings LLC, Houston, Texas *.
Employer of Deepwater Horizon Crew: Transocean Deepwater Inc., Houston, Texas *.
Employer of Land-Based Crew: Transocean Offshore Deepwater Drilling Inc., Houston,
* registered in Delaware.
Deepwater Horizon was an exploratory rig not an extractive oil rig, When Deepwater
Horizon was lost, she was in the process of completing exploration by capping the well
before moving to another exploration site. This required the rig to seal the oil well and
separate its riser piping from the wellhead to the rig. Subsequently, a production rig
would have come to access the sealed wellhead, open the well, and produce oil from the
open well.
Drilling in the oil patch or offshore is an expensive operation with no return on
investment until oil begins to flow. Currently, day rates for MODU’s vary from
$300,000 to $400,000 (1)1. Indeed, pressure was on BP to finish the exploratory phase of
the drilling, seal the well, and move Deepwater Horizon to her next drilling site. At the
Macondo site, the drilling was about six weeks behind schedule costing approximately
$500,000 a day (2).
The media reported estimates of the total amount of oil spilled in the Gulf of Mexico
through the loss of Deepwater Horizon varied from about 570,000 tonnes2 to 690,000
tonnes and claimed that it was the worst spill in US history, even larger that the Exxon
Valdez spill.
The tanker Exxon Valdez spilled 37,000 tonnes in Alaska, 1989, which today ranks as 35th
in magnitude of tanker spills. The largest tanker spill to date is the Atlantic Empress,
which spilled 287,000 tonnes in Tobago, 1979 (3).
For comparison, major well blowouts are listed in Table 3.
Table 3. Major Well Blowouts.
Ixtoc I
1979-1980 463,000 tonnes
Persian Gulf 1983
265,000 tonnes
Santa Barbara Channel
13,300 tonnes
It could be concluded that the Deepwater Horizon loss resulted in the largest oil spill in
the world to date. The statistics not readily available are the environmental and
economical costs of the spills.
Investigations, blame, claims, lawsuits, etc., still appear regularly in the media and on
the Internet. However, I wish to address only one of these.
In June, NSPE Executive Director Larry Jacobson issued a statement about the
Deepwater Horizon oil spill and licensed professional engineers. He stated that the
only way that government and the public could have some assurance that industry is
putting the public ahead of profit is, at a bare minimum, to require the licensing for all
1 Number in parentheses denote References.
2 1 tonne of oil = 7.2 barrels. 1 barrel = 42 US gallons.
engineers who provide engineering services that involve safeguarding life, health, or
property. Discussions solicited by NSPE from four experts as well as letters to the
editor appeared in the Aug|Sept 2010 issue of PE .
In general, the letters and discussions agreed with the proposition that having the
drawings of MODU’s signed by licensed professional engineers could prevent or, at
least, reduce the likelihood of such offshore disasters
It is naïve to believe that signing drawings of mobile offshore drilling units (MODU) by
licensed engineers will decrease the likelihood of disasters such as the BP oil spill. Such
a requirement does not eliminate possible operational shortcomings, e.g.:
Loss of situational awareness on the part of crew members.
Deferred (i.e., postponed) maintenance.
Inadequate crew training.
Uncertain chain of command.
Operation long after design life was exceeded.
My association with the marine industry began with the design , construction and
repair of MODU’s. When an owner of many of our rigs was told that the cause of
somewhat frequent repairs to his rigs was abuse by crews, he replied “If my men can’t
break it [the rig], they ain’t working hard enough!” Speed in the completion of well
drilling was, is, and will be, a fact of life in the hydrocarbon industry.
Also, signing drawings by licensed engineers will not preclude overlooked design
flaws, witness the recent failures of highway and pedestrian bridges, tower cranes,
infrastructure, gas turbines (e.g., Quantas engine fires), etc.
Indeed, this approach adds ammunition to those who believe that such a requirement is
just a union-like membership expansion. Also, it implies that the engineers who
participate in the design and construction of MODU’s are not competent. MODU’s are
extremely complex and require design teams of structural, welding, materials,
mechanical, and electrical engineers and naval architects.
Engineers who design and manufacture aeroplanes, gas turbines, and ground vehicles
(all very complex in requirements and performance), are not required to be licensed but
I would not question their competence.
Finally, the customer for whom a product such as a blow out preventer is designed and
manufactured may decide that certain redundant features add cost and demand their
elimination. The manufacturer can point out the necessity for the inclusion of such
features but, at the end of the day, the customer is always right. We all observe or
experience that management trumps engineering with increasing frequency.
Management trumping engineering is illustrated in Ref. 4.
Who Was in Charge?
The question “who was in charge?” was raised in the Aug|Sept 10 issue of PE .
The answer is “a troika.”
Transocean, the owner and operator of Deepwater Horizon, register their MODU’s
under foreign flags, specifically, flags of convenience. Such a registration is attractive
Taxes levied by the flag-state are much less than if the rig were flagged in the
United States. In many cases, there is no tax at all.
The laws and regulations addressing safety, structural and mechanical condition,
crew competence, and crew welfare are more lenient than required by the United
Deepwater Horizon was registered in the Marshall Islands (Marshall Islands Registry
corporate headquarters, Reston, Virginia). Flags of convenience are described in Ref. 5
and discussed in Ref. 5.
On Transocean MODU’s, the captain (a licensed ship’s master) is in command only
while the unit is underway or during an emergency. When the unit is on-station and
drilling, the Offshore Installation Manager (OIM), who does not have to be a licensed
master, replaces the captain and is in charge of all unit operations. Both the licensed
captain and the OIM are Transocean employees and, to complicate the issue in this
instance, a charterer’s representative who is a BP employee is also on board. The
charterer’s representative is rarely a licensed mariner, but can make operating and
safety decisions while on-station and drilling.
During the joint United States Coast Guard/Minerals Management Service hearings,
crewmembers from Deepwater Horizon detailed the difficulties working with the chain
of command that included the captain, OIM, and BP rig manager. When the emergency
occurred, the vessel’s International Safety Management Code called for the two senior
officials on board, the OIM and BP representative (but not the captain), to go to the
scene of the emergency and determine the next course of action. During the vital
minutes after the explosions, , the order to activate the emergency disconnect switch
and shut down operations was not given by the captain. He admitted waiting to ask
permission from the OIM first.
In contrast, most companies operating MODU’s have a policy where the licensed
captain is also certified as the OIM on board. Thus, the same individual is in charge
whether the unit is underway or on station and drilling.
The Marshall Island Registry, which only required Transocean to meet the less stringent
international regulations of the International Maritime Organization, permitted an
unlicensed OIM to be in charge of Deepwater Horizon during drilling operations
(illegal under US law). Indeed, the US Code of Federal Regulations requires that on US-
flagged mobile drilling rigs, the OIM must be licensed as a master, and the master of a
US-flagged mobile drilling rig must also be endorsed as an OIM.
The troika aboard Deepwater Horizon is discussed in detail in Ref. 7.
The signatures of licensed professional engineers on design drawings will not prevent
offshore disasters because they have no impact on the subsequent service 3.
Our last line of defense against such offshore disasters is rigorous inspection and
enforcement in compliance by federal agencies such as the USCG, DOE, EPA, etc. In
the light of today’s climate, such actions by the federal agencies are uncertain due to
limited funding and industrial pressure on such agencies through Congress.
Also, MODU’s drilling on the Continental Shelf, although beyond the three-mile limit,
should be flagged in the US and required to conform to US standards in the
performance, training and certification of crew members, safe operation, and the
operational status and maintenance of critical equipment.
1. “By the Numbers, “ Marine News , Oct. 2010, p 56.
2. “Money, didn’t trump safety, spill probe says,” Tribune Newspapers , 9 Nov. 2010.
3. “Number of oil spills continues to decline,” Tanker Operator , March 2010, p iv.
4. Jule A. Miller, FAWS, in “Slippery Places” How the Delusions of Modern
Management Destroyed an American Manufacturing Firm,” published by, 2008.
7. Captain Kelly Sweeney, “Mobile Offshore Drilling Units in Gulf Should be US-
flagged,” Professional Mariner , September 2010.
NSPE member Harold S. Reemsnyder PhD, PE, CEng, FWeldI, has been a Registered Structural Engineer in the
Commonwealth of Pennsylvania for 52 years and a Chartered Welding Engineer in the United Kingdom for 21 years.
He can be reached at
It should be kept in mind, that all marine vessels – ships and MODU’s – are designed,
built, and periodically surveyed in conformance with the rules of the pertinent classing
society (in the present case, the American Bureau of Shipping).