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Subsea BOP Dropped Incidence by Rig Contractor - Lesson Learning
26 May 2020
Over a decade there are major Subsea BOP dropped incident happen, Does anybody has any track records how many incident,what are root cause and cost impact to operator? 
Please share for learning purpose.
Thanks, Mahesh
12 answer(s)
Beach Energy
Total Posts: 2
Join Date: 30/09/10
Although root cause missing, for frequency data can use IOGP statistics published for free in IOGP Risk Assessment Data Directory Report No. 434 – 8 (Mechanical Lifting Failures). Some other useful references in the document. The data shows the probability of a dropped object per lift. Estimation of the dropped object frequency can be derived from the probability of a dropped object per lift combined with the number of lifts carried out.
SPREAD Associates
Total Posts: 149
Join Date: 05/03/08
Hi Doug,

Thanks for putting the record straight - my memory clearly isn't what it used to be!

All the best!

Drilling Specialist/Well Engineer/Training Consultant
Kingdom Drilling
Total Posts: 461
Join Date: 10/01/05
Iadc deepwater well control guidelines 1st edition supplement 1. 

Had recommendation after a spate of physical and human error failure events also! 

I’ll see if I can find this and attach it in a further post.
Drilling Supt (Consultant PE)
SPREAD Associates
Total Posts: 2
Join Date: 15/08/17
Scott McNeil,

The incidents you were referring to (late 90's early 2000's) was the grease on the drilling line getting on the "new disk brakes" and as the riser was being lowered (and getting building mass, not necessarily weight due to buoyancy), the disk crakes couldn't get a grip and the riser and bop would just keep moving building up MV.  

I recall it was a simple solution initially:  Putting a barrier between the disk brakes and the drilling line.

Doug White
Sugar Land
Consultant ( sort of retired but keeping in touch )
SPREAD Associates
Total Posts: 39
Join Date: 27/03/11
A side issue but food for thought.
Anybody reusing the ST-2, ALT Squnch joint or similar connector must get them inspected before reuse.
IE do a full 100% wet UV MPI on both pin and box connectors. The O ring and Lock Ring have to be removed before inspection. It’s their grooves where any cracks will most likely occur.
The lock rings are easy to remove, we used to use two motorcycle tyre levers.
regards Howard
SPREAD Associates
Total Posts: 149
Join Date: 05/03/08
Hi Mahesh,

There was a spate of dropped BOP's when the 5th Generation SS rigs first came out in the late 90's and early 2000's.

I wasn't involved with any of them, but I have a vague recollection that in several cases the root cause was the type of grease used on the drilling line affected the sensors controlling the draw-works.

As a result, the computer got confused to where exactly it was and spooled out the drilling line in an uncontrolled manner.

I'm sure a websearch will find several photos of the TDS & travelling blocks on the rig floor, as there were quite a few doing the rounds at the time.....

All the Best!

Documents uploaded by user:
TFE Wreck.jpg
Drilling Specialist/Well Engineer/Training Consultant
Kingdom Drilling
Total Posts: 461
Join Date: 10/01/05
My own assessments of riser failures from within evident data that can be found. .

Thry generally fail when they are sitting just off the seabed, not connected. 

This is when combined forces are at their greater and most risks are at play.?

Stena drillships last Quite recent riser failure,  offshore Canada? A Planned disconnect due to Weather that then went evidently wrong due to several reasons! 

This accident event that was it should be stated duly and very diligently investigated by Stena. With major learnings that they did translated were shared and are today hopefully bring sustained today via  evident ( physical ( parts) people and paperwork) corrective actions taken.  

They also shared learning to anyone that was interested and asked. Fair play and hats off to Stena.

A safety strategy approach that we as an industry need far more off. 

Learning from all our failures! 

Where we need simple investigative evident gathering methods. People trained to do this and most importantly a culture that avoids the blame game. Eg via a ‘latent cause analysis’ or similar no blame investigative method. 
Drilling Specialist/Well Engineer/Training Consultant
Kingdom Drilling
Total Posts: 461
Join Date: 10/01/05
Dropped objects?

Categorically no No NO! These are non -  injury Accident related events
That sit pretty high in the top quadrant of most companies risk matrixes. So why are there so few investigative reports? . 

Part of this 95-97% where all drilling problems are! ( studies evidently prove this) 

All Accidents ( injury and non injury related) are EVIDENTLY caused.

ALL accident must be investigated ( company policy?) Where all evident active and latent failures can then be determined and evaluated? 

Where are the investigative reports that we are all accountable to be producing? 

Where are the translated  and sustained learnings?. 

Wake up people, stop following the same pied pipers playing the same failing tunes! 

Put all the time you spent at university supposedly educating yourselves to good use. 

Start with the person who is making all these same failures! I am! 

Do something different 
Start to Challenge all failures today to change tomorrow. 

Consultant [retired Shell staff]
SPREAD Associates
Total Posts: 273
Join Date: 02/09/05
Excellent answers, so far...
Indeed, riser (connectors, inspection, ...) and elevators bring back long lost memories...
I recall a Shell system called "Drilling Equipment Newsletters, (DEN for short) which was started in 1983, where the good and bad equipment was highlighted. Everyone liked their own HiiLites and very few loved their own loLites.
So for these we had to fish also outside Shell waters.
One day, visiting an offshore installation, I read in the"Offshore" magazine on the rig, where the Norwegian Petroleum Institute - NPD (October 1983) banned a certain elevator after Two BOP/riser drops!
 When trying to make it into a DEN, lots of colleagues objected because everybody read the "free" magazine, it has nothing to do with our operations etc. I did insist and the LoLite was published as a Shell DEN. On the very same day, we had two thankyou responses: One from Gabon, where they were using the very same Elevator; the other came from Egypt, where they had it in stock ready to be used. That was the feedback the DENs needed!
 PS The elevator safety factors were proven too low it as they omitted dynamics. One elevator exploded in 1998 on Friday of week #5.
Rogaland Forskening   did measure elevator strains as high as 150%. Varco Load tests helped in the issue and finally API Spec 8 Hoisting was updated to include all the lessons above.

Consultant ( sort of retired but keeping in touch )
SPREAD Associates
Total Posts: 39
Join Date: 27/03/11
In the early 1970’s there was a series of marine riser connection failures and many cracked connections ( pin and box but primarily pin ) Vetco, Cameron and Regan. 
Vetco and Cameron were mainly due to material selection, ie risers manufactured for warm water the brought into the NS.
Regan appeared to be a design fault and a modified pin connector with a load bearing ring still cracked, behind the load bearing ring.
Vetco Inspection found the best And only method of connector inspection was by wet UV MPI.
In the early 1980’s a series of dropped BOP stacks caused concern. Identified as elevator failure. One failure was over 2kg of weld repair on the elevator. Introduction of API 8C and load testing of existing elevators culled many suspect elevators from service.
Main concern apart from elevator condition ( inspection and service) was the dynamic loading on the elevator when running the BOPstack.
Some companies then insisted the minimum elevator capacity was 500 ton and not 350 when running BOP stack. Some insisted on dedicated elevators for BOP stack running.
I would still argue today that Marine Riser connector inspection needs reviewing as does the quality of the service and inspection of elevators. Around the world the competency of Hosting Tool inspection I think leaves a lot to be desired.
Regards Howard
Consultant [retired Shell staff]
SPREAD Associates
Total Posts: 273
Join Date: 02/09/05

Subsea BOP dropped on the seafloor Complement

Main cause: Riser failures (Balljoints; Telescopic joint bolts failure, 1993¸ Vortex Induced Vibrations VIV –Rx: Helical strakes, K/C lines helically disposed, …)

1980 – Off Norway Pentagone 89 “Alexander L. Kielland” turned turtle, 123 killed.  Misuse of 1 of the 2 false legs. ssBOP drop.

(1984 The above BOP was fished and reused on ODECO´s “Ocean Voyager”)

1982 Pelikan, off Tunísia. Slip joint failure: ssBOP on seafloor, fracturing subsea low pressure wellhead.

1982 UKOOA Ageing of BOPs tests

1983 Deep Sea SAGA Drop ssBOP, fished in 3 pieces

1984? Discoverer Seven Seas ELF, ssBOP adding Vetco Tie down Rods

1985?  IADC/SPE 23901 Subsea BOP inspection, CHEVRON

1985 Exxon´s  18 ¾” 15K BOP test results

1985 ssBOP incidents, SINTEF Norway

1986? NIT (Norwegian InstituteTrondheim)

1986 Sintef

1987 ssBOP Reliability, SINTEF

1991 December SPEDC Sintef report

1994 Shell UK BOP QRA?

Other experts in subsea BOP inspections: MODUSpec, WESTHou, Veritas Associates?, Graham Singleton . Paul Contarini, Ken Dupal

Well Construction Lead
Total Posts: 24
Join Date: 27/02/16
Hello Sir

No track records of such incidents to my knowledge, reason as I understand is that stakeholders were/are shy about it.
I can share the publication reference below which explains briefly cause of a lost BOP case but more interesting is about how it was recovered.
I was involved on this 1999 case on the Operator’s side as drilling superintendent when the lost BOP incident occurred.

This paper written by the drilling contractor is unique to my knowledge and really good as basis approach for any recovery attempt.

I take the opportunity to congratulate Paul Contarini at Al for their outstanding leadership in this case. THANKS Paul!

SPE/IADC 67808 - Pride Africa - Successful BOP and Riser Recovery Offshore Angola

P.Contarini, A.Zanchetta, P.Jeannet, M.Choquet, D.Sauteron, J.L Puyaubran/Pride Foramer-Sonamer, T.Duhen/Pride Int'l


Posted by

Mahesh Picha

Sr Lifecycle D&C Engineer


Total Posts: 15
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