Dynamic Positioning Incident Results in Sheared Wellhead Tree


Dynamic positioning controls. Photo © Robert Almeida/gCaptain

The U.S. Bureau of Safety and Environmental Enforcement (BSEE) and the U.S. Coast Guard have today issued a Joint Safety Alert in response to a dynamic positioning incident involving an Offshore Support Vessel while conducting critical activities on the Outer Continental Shelf, resulting in the loss of position.

Without going into detail on where and when the incident occurred, the joint alert said that the OSV lost position while attached to a wellhead, severing the wellhead tree and causing a lubricant release on the platform deck and to the environment.

Safety Alerts are issued by BSEE to inform the offshore oil and gas industry of the circumstances surrounding an incident or a near miss, and also contain recommendations that should help prevent the recurrence of such an incident on the OCS.

The full text of the safety alert, Coast Guard Alert 01-15 or BSEE Alert #315, can be read in full below:

[B]
DYNAMIC POSITIONING SYSTEM FAILURES ON OFFSHORE SUPPLY VESSELS ENGAGED IN OIL AND GAS OPERATIONS IN THE U.S. OUTER CONTINENTAL SHELF[/B]

[B]Discussion: [/B]

This Joint Safety Alert addresses a dynamic positioning (DP) incident involving an Offshore Supply Vessel (OSV) which resulted in a loss of position while conducting a critical Outer Continental Shelf (OCS) activity. The OSV was attached to a wellhead, lost position and severed the wellhead tree causing a lubricant release on the platform deck and to the environment. Immediately prior to the position loss, the OSV had multiple DP system alarms and failures, including loss of bow thruster and engine control. No attempt was made to identify or correct the causes of these failures and the operations continued.

At the time of the position loss, the OSV was being utilized to support pump and electric line equipment which was connected to the well at the time of the incident. Specifically, when the vessel lost position, the vessel operator was in the process of removing a downhole DX plug from the well via wireline. High pressure pump lines were also connected to the well, although actual pumping operations were not in progress. When the vessel lost position, the Christmas tree was sheared from the well because of the force exerted on it by virtue of the connected high pressure lines. Severe consequences were averted because a subsurface safety valve was activated and there was an absence of hydrocarbon flow from the well.

The OCS activity performed was critical due to the short time to terminate and the potential uncontrollable release of hydrocarbons from a well with known sustained casing pressure. The Coast Guard and the BSEE are issuing this joint Safety Alert because we share jurisdiction on the OCS and wish to highlight the importance of an OSV’s Safety Management System (SMS) and a leaseholder’s Safety and Environmental Management System (see Reference 1).
This incident highlights the following critical issues:

[B]Alarms: [/B]The Coast Guard and BSEE stress the importance of properly acknowledging and investigating all alarms, and taking immediate and positive corrective action prior to initiating or proceeding with any critical OCS activity.

[B]SMS: [/B]The OSV was not required to and did not have an International Safety Management (ISM) Code certificate. The Coast Guard reminds OSV owners and operators that an effective SMS is essential to safe operations, particularly when those operations are critical OCS activities. Had the OSV implemented an effective SMS, as described in the ISM code, it likely would have:

[ol]
[li]Had adequate emergency disconnect capability and procedures for loss of position events and personnel trained in those procedures. In this case the OSV did not have adequate emergency disconnect capability, procedures or training records;[/li][li]Ceased the critical OCS activity after experiencing multiple DP system failures – including engine and thruster loss – and not have resumed the activity until after correcting the causes of the DP system failures (see Reference 2).[/li][/ol]

[B]Dynamic Positioning:[/B]
The Coast Guard strongly recommends owners and operators of OSVs using DP to follow DP guidance provided in reference 3 (Marine Technology Society (MTS) DP operations guidance) when conducting critical activities on the U.S. OCS. See the applicable notice on this topic published in the Federal Register (77 FR 62247, October 12, 2012) for more details. Had this OSV followed the MTS DP operations guidance it likely would have:

[ol]
[li]Had a DP system that met a minimum of DP Equipment Class 2 (DP-2). The involved OSV’s DP system was DP Equipment Class 1 (DP-1), which means that a loss of position may occur in the event of a single failure. (see Reference 3, paragraph 4.1);[/li][li]Had an Activity Specific Operating Guideline (ASOG) that prescribed emergency disconnect procedures and capability to prevent equipment damage and pollution. The involved OSV did not have an ASOG defined. The sample ASOG in MTS DP guidance recommend the operator should “halt operations and initiate contingency procedures” for thruster and generator failures, which this OSV experienced prior to the loss of position incident. (see Reference 3, Appendix C);[/li][li]Had a Critical Activity Mode of Operation (CAMO) defined. The involved OSV did not have a CAMO defined. The sample CAMO in MTS DP guidance recommend the operator change operating condition from “normal operations” to “informative/consultative status (risk assess)” when any change occurs to the normal operations of the DP system, which this OSV experienced prior to the loss of position incident. (see Reference 3, Appendix C);[/li][li]Ensured a structured competence assurance program was applied to all key DP personnel. At a minimum DP personnel should be required to demonstrate proficiency in understanding the redundancy concept and emergency procedures to respond in the event of a DP system failure. (see Reference 3, paragraph 4.14).[/li][/ol]

[B]Leaseholder/operator SEMS: [/B]
BSEE strongly recommends leaseholders/operators consider Coast Guard recommendations for DP vessels when evaluating potential hazards and establishing/implementing contractor safe work practices in their SEMS program (see 30 CFR §§ 250.1911 and 250.1914). BSEE reminds leaseholders/operators of their critical role in ensuring safety and environmental hazards associated with contracted vessels on their lease are properly managed. For example, leaseholders/operators should ensure hazards associated with a loss of position by contracted DP vessels are analyzed and managed with appropriate contractor safe work practices.

For additional information, contact Lieutenant Commander Elizabeth Massimi at (504) 671-2156 with the Coast Guard District 8 Prevention Division or Troy Trosclair at 504-736-2923 with the BSEE Gulf of Mexico Region.

Reference 1: BSEE/USCG Memorandum of Agreement OCS-07 “Safety and Environmental Management Systems (SEMS) and Safety Management Systems (SMS)” (April 30, 2013).

Reference 2: ISM Code Regulations 7 and 10 (2014 ed.).

Reference 3: DP Operations Guidance, Part 2 Appendix 2: DP Project /Construction Vessels (Dynamic Positioning Committee of the Marine Technology Society to aid in the safe and effective management of DP Operations (July 31, 2012).

Reference 4: Marine Technology Society Technical and Operations Guidance (TECHOP) “Defining Critical Activities Requiring Selection of Critical Activity Mode”, TECHOP_ODP_12_(O) (January 2014).

I understand why the BSEE did not release the name of the involved vessel, but curious minds abound. Anyone have the scoop on who this was and exactly what went wrong?

Could it have been a DGPS problem. I know that we were having DGPS problems last month attributed to sun spots. Both DGPS and the one that belonged to the customer all of a sudden said we were 7 meters off station and all the thrusters ramped up to put us back where it thought we were supposed to be. While the DPO wrestled to settle her down, the DGPS changed their mind and decided we were where we were supposed to be in the first place Happened 2 or 3 times in about a 3 day period.

[QUOTE=txwooley;155419]I understand why the BSEE did not release the name of the involved vessel, but curious minds abound. Anyone have the scoop on who this was and exactly what went wrong?[/QUOTE]

[I]"Had adequate emergency disconnect capability and procedures for loss of position events and personnel trained in those procedures. In this case the OSV did not have adequate emergency disconnect capability, procedures or training records;
Ceased the critical OCS activity after experiencing multiple DP system failures – including engine and thruster loss – and not have resumed the activity until after correcting the causes of the DP system failures (see Reference 2).[/I]

From the report. If it was z-drive, sounds like a generator went down and they lost one side of the switchboard. Or if it was conventional drive then lost the ability to twin screw. Either way, there should be someone out on deck if a hose is attached. Even if you aren’t pumping…so you can disconnect in an emergency. Maybe there was but the guy was too busy to react. Says, “[I]the vessel operator was in the process of removing a downhole DX plug from the well via wireline[/I]”. Not sure what that means, but sounds complicated. Why would the DPO be doing something other than watching the DP system? Was it just one guy up there? Too many unanswered questions.

DP-1 vessel for that kind of operation? That’s just plain stupid.

Really interested in knowing where this occurred! Seriously, what were they thinking using a DP-1 boat?? I am surprised there aren’t regulations about that type of thing.

Sounds to me like they were doing P&A operations from the boat. I’ve done it plenty on a DP-1 vessel. It’s definitely a shitty job and you always have to be on your toes because of the extended time hooked up to a hose and the short length of hose provided.
I will say that was on a boat with two bow thrusters, a good stern thruster, and plenty of power. Without those things it would have been a much riskier proposition.

Hello All,

Thanks, Rob for posting this. This is further indicative of the USCG’s intent with the NPRM that was released in November of last year. The “strong” recommendations are almost verbatim from the NPRM.

I have been trying to find additional information on this but have had no luck. I think that the incident report may be poorly worded and therefore misleading. Judging by the project that was being undertaken I would surmise that this was actually a DP2 vessel that was on station performing the work. The vessel experienced several alarms and subsequent loss of redundancy. As a result, it was operating at a redundancy level equivalent to DP1 prior to the increasing severity of failures. I believe this is what the report was attempting to get across but was not clear.

I would certainly appreciate any insight that anyone here has regarding the situation and again - as posted in a related thread - please take the time to read through and comment on the NPRM as we can expect to see much more of this type of reaction from the USCG in the future.

FWFS

no it was a DP-1 vessel

Had a DP system that met a minimum of DP Equipment Class 2 (DP-2). [B][U]The involved OSV’s DP system was DP Equipment Class 1 (DP-1)[/U][/B], which means that a loss of position may occur in the event of a single failure. (see Reference 3, paragraph 4.1);

Was wondering whether a single point failure (for ex. thruster failure) makes a DP2 vessel a DP1 vessel even though it’s still capable of carrying DP2 operations. Or whether the vessel is allowed to carry on with operations so to stay insured?
What doc shall refer to?

Flash_Royal,

This is not as straightforward a question as you might be hoping. The vessel’s DP Class is, in reality, just a number assigned to the vessel by a Class Society based on how its design compares to their design requirements. In other words, a DP2 vessel is still a DP2 vessel regardless of its operating condition.

Whether it should be continuing an operation, or even taking on a particular task to begin with is a completely different story. Class notation aside, what type of vessel is it and what is its redundancy concept? What kind of operation is being undertaken?

A very general, but comprehensive summary can be found in IMCA M04/04, p. 9, “What are the objectives of an FMEA? - …Where DP is concerned, the objective is to develop a fault tolerant system that can not only hold station in the face of adverse circumstances, but allows faults to be corrected as they occur, [U]without jeopardy to the operation at hand[/U] (emphasis added).”

With this in mind, in the example you present, let’s assume that this is a DP2 PSV operating with three forward thrusters and two azimuths aft. If the vessel then loses a forward thruster its overall remaining capability has to be assessed. For example if this thruster is powered from the Port side of a split switchboard does the actual Worst Case Failure now shift to the Stbd side switchboard? Will the loss of the Stbd side switchboard then result in a failure that exceeds the Worst Case Failure Design Intent and thereby jeopardize station keeping capability? If so, a risk analysis must be undertaken and consideration should be given to ceasing operations until the thruster can be repaired.

In a different example, a semisubmersible (still DP2) with 6 or more thrusters and multiple switchboards (more than 2) operating in an open configuration or with a robust Advanced Generator Protection system may be able to remain in operation (still following a risk analysis, however).

The critical tool is always a proactive risk analysis on the part of the operating personnel. This is the whole purpose of the Critical Activity Mode of Operation (CAMO), Task Appropriate Mode (TAM), Activity Specific Operating Guidelines (ASOG), and other decision support tools.

As far as references go, general guidance is in MTS DP Operations Guidance, IMCA M04/04, and of course, IMO MSC Circ. 645. However, these are only guidelines and need to be applied to the specific operating principles that SHOULD be contained in the vessel/asset’s DP FMEA, DP Operations Manual, and CAM/TAM/ASOG (generated in associated with the FMEA analysis) - all of which should be specific to each and every vessel.

[QUOTE=Flash_Royal;163745]Was wondering whether a single point failure (for ex. thruster failure) makes a DP2 vessel a DP1 vessel even though it’s still capable of carrying DP2 operations. Or whether the vessel is allowed to carry on with operations so to stay insured?
What doc shall refer to?[/QUOTE]
It might but that all depends on the amount of eqipment it has over and above minimun DP2 requirments and your consequence analysis is going to warn you of that for a start

      • Updated - - -

[QUOTE=ChiefChad;164743]Flash_Royal,

This is not as straightforward a question as you might be hoping. The vessel’s DP Class is, in reality, just a number assigned to the vessel by a Class Society based on how its design compares to their design requirements. In other words, a DP2 vessel is still a DP2 vessel regardless of its operating condition.

Whether it should be continuing an operation, or even taking on a particular task to begin with is a completely different story. Class notation aside, what type of vessel is it and what is its redundancy concept? What kind of operation is being undertaken?

A very general, but comprehensive summary can be found in IMCA M04/04, p. 9, “What are the objectives of an FMEA? - …Where DP is concerned, the objective is to develop a fault tolerant system that can not only hold station in the face of adverse circumstances, but allows faults to be corrected as they occur, [U]without jeopardy to the operation at hand[/U] (emphasis added).”

With this in mind, in the example you present, let’s assume that this is a DP2 PSV operating with three forward thrusters and two azimuths aft. If the vessel then loses a forward thruster its overall remaining capability has to be assessed. For example if this thruster is powered from the Port side of a split switchboard does the actual Worst Case Failure now shift to the Stbd side switchboard? Will the loss of the Stbd side switchboard then result in a failure that exceeds the Worst Case Failure Design Intent and thereby jeopardize station keeping capability? If so, a risk analysis must be undertaken and consideration should be given to ceasing operations until the thruster can be repaired.

In a different example, a semisubmersible (still DP2) with 6 or more thrusters and multiple switchboards (more than 2) operating in an open configuration or with a robust Advanced Generator Protection system may be able to remain in operation (still following a risk analysis, however).

The critical tool is always a proactive risk analysis on the part of the operating personnel. This is the whole purpose of the Critical Activity Mode of Operation (CAMO), Task Appropriate Mode (TAM), Activity Specific Operating Guidelines (ASOG), and other decision support tools.

As far as references go, general guidance is in MTS DP Operations Guidance, IMCA M04/04, and of course, IMO MSC Circ. 645. However, these are only guidelines and need to be applied to the specific operating principles that SHOULD be contained in the vessel/asset’s DP FMEA, DP Operations Manual, and CAM/TAM/ASOG (generated in associated with the FMEA analysis) - all of which should be specific to each and every vessel.[/QUOTE]
I just love it when someone talks standards that we all follow but in the GOM you have unclassed vessels with unclassed DP systems out there…only 150 of them I hear

ChefChad,

Many thanks for a profound answer.

Here is some more details for you to have a bigger picture. So you could give more info maybe having that in mind.

That is Cable Laying vessel. We have 2 tunnel, 2 retractable in front and 4 azimuths in aft. 2 separated switchboards. Each switchboard has 1 tunnel, 1 retractable and 2 stern thrusters.

[QUOTE=txwooley;155419]I understand why the BSEE did not release the name of the involved vessel, but curious minds abound. Anyone have the scoop on who this was and exactly what went wrong?

Could it have been a DGPS problem. I know that we were having DGPS problems last month attributed to sun spots. Both DGPS and the one that belonged to the customer all of a sudden said we were 7 meters off station and all the thrusters ramped up to put us back where it thought we were supposed to be. While the DPO wrestled to settle her down, the DGPS changed their mind and decided we were where we were supposed to be in the first place Happened 2 or 3 times in about a 3 day period.[/QUOTE]

It was a calm day, no wind, no current and flat seas. The DP Oilfield Supply Vessel and the pump was directly below the wellhead and only 2’ from the plus 10 deck on the platform. One could step from the vessel to the plus 10… There was only 100’ of hose utilized from the pump to the tree. Used the hose to pressure test the wireline lubricator and to bleed off. While running in the hole with wireline the vessel did not loose power, it kicked into forward gear running away from the platform. When it was noticed that the boat was moving there was an attempt to disconnect the hose and were close to having it done but the hose started tightening and personnel were told to back away from the connection, thinking the hose would part. The hose did not part and pulled on the tree until the 8 bolts snapped. The hose and the tree were left dangling 100’ below the vessel. 200’ of water. There was 3000+ psi on the well. Fortunately it was a gas well and not an oil well, no oil was spilled. The wireline operator released the pressure on the SCSSV shutting the well in. The vessel moved about 1/2 a mile before they could get it shut down.

All future operations will have an emergency quick disconnect on the hose. Immediately after pressure testing or when the hose does not have to be hooked up the hose will be disconnected. An extra 100’ of hose will be added to provide more time to disconnect in case of problems as the supervisor was told to install but did not.

The vessel had stated they had problems with the vessel but that it would lose power. Due to the calm seas and current the well work continued. Never expected it to kick in gear and take of full steam ahead.

I was told the computer told the vessel to go and it did.

Once bitten, twice shy.

There had to be some Human error in this incident. I can’t believe the vessel did a half mile run-off on it’s own.

Just dumb Americans on a cheap American boat with no Norwegian or Finnish technology.

[QUOTE=AHTS Master;184286]There had to be some Human error in this incident. I can’t believe the vessel did a half mile run-off on it’s own.[/QUOTE]
rarely ever does
either the DPO did it or he let it happen
but crikey doing that job on GPS alone WTF?

forgot to add GPS on IALA corrections no doubt…