ACCIDENT INVESTIGATION REPORT - DEEPWATER NAUTILUS DROPS TRAVELING BLOCK CAUSING RIG DAMAGE

ACCIDENT INVESTIGATION REPORT - Deepwater Nautilus Drops Traveling Block CAUSING RIG DAMAGE

On June 9, 2014, the Transocean Deepwater Nautilus experienced an uncontrolled descent of the traveling block and top drive while on Shell's Glider 007 well, located in Green Canyon 248, OCS-G 15565. The Deepwater Nautilus had been on the Glider 007 well for 121 days and had drilled to a Measured Depth of 16,198 feet. The Bureau of Safety and Environmental Enforcement Investigation Team prepared the following report using personnel statements, requested documentation, and detailed incident reports provided by Transocean and Shell.

While in the process of pulling drill pipe out of the hole, the crew was taking pressure readings of the formation utilizing the Measurements While Drilling (MWD) tools located on the drill string. After the first pressure test had been completed, the Driller prepared to space out the drill pipe so that it could be disconnected, transferred to the pipe racking system (PRS), and placed into the pipe racks for storage. Once the pipe was in place, the crew prepared to disconnect the pipe and drain the remaining fluids before initiating the transfer. After the excess fluid had been drained, the Driller attempted to set the brakes on the draw works to close the torque wrench on the Top Drive System so the pipe could be transferred to the PRS. When the Driller tried to set the brakes on the draw works, he received a 'Maintenance Torque up Time Out for Internal Brake Release' fault alarm on his screen. The system is designed to stop all operations if a brake fault alarm occurs during operations.  The Driller was unable to make the transfer due to the fault, and the crew began troubleshooting the issue.

The Driller called the Mechanics and Electrical Technicians (ETs) to the rig floor to assist with the problem. The Mechanic arrived to the drill floor and started trouble shooting the problem. The Mechanic then went to the Driller's console and called the Chief E.T. to request a reset of the drives. The Driller attempted a 'soft reset' of the system from the control screen located on his console, but the fault alarm did not clear. The crew continued troubleshooting the issues and the Toolpusher relieved the Driller so that he could eat lunch.

The Chief E.T. then went to the Starboard Motor Control Center, where drives # 1, 2 & 3 are located and performed a 'hard reset' of drive #1. This action usually fixed the previous alarms but did not clear this fault. After performing the hard reset, the block and drill pipe began to move up and down on its own approximately 6 inches for around 10 seconds. The Driller, on his way to lunch, saw the movement and ordered all personnel to clear the rig floor. During this time, the Chief E.T. had made his way over to the Port Motor Control Center, where drives #4, 5, & 6 are located, and saw the same fault on drive #4. The Chief E.T. called the Driller's cabin to confirm that the draw works brakes were set so he could perform a 'hard reset' of drive #4.

The Toolpusher, who was now sitting in the Driller's chair, took the call and said something to the effect of "the brakes are not set" at the same time an announcement was being made over the rigs intercom system. The Chief E.T. misunderstood and thought he heard "brakes are set" and reset drive #4 without confirming the response.

The 'hard reset' interrupted the control to the drive motors, which were still holding up the top drive, and caused the traveling block to freefall. Upon seeing the drill pipe start to buckle towards the drill shack, the Assistant Driller pulled the 'Fire-Axe Handle', which is designed to dump the hydraulic pressure from the draw works brake circuit in an emergency, causing the breaks to slam shut and stop any decent of the top drive. The breaks shut, but due to the momentum for the top drive, failed to stop the traveling block from falling to the rig floor. The fall caused damage to the drill pipe, the Driller's shack, and the traveling assembly. No injuries or pollution were reported after the incident.

LIST THE PROBABLE CAUSE(S) OF ACCIDENT:

Poor Communication: Poor communication between the crew members led to confusion and misleading information in all areas of the operation.

- Crew members failed to properly investigate maintenance alarms before attempting to reset the draw works.

LIST THE CONTRIBUTING CAUSE(S) OF ACCIDENT:

None

LIST THE ADDITIONAL INFORMATION:

On July 4, 2014, the crew onboard the Deepwater Nautilus was in the process of changing out equipment and performing acceptance testing to prove the integrity of the system. The crew noticed an excessive heat buildup in the braking system, and after setting the brakes, began investigating the cause. During the troubleshooting process, plugs were installed on a section of vent piping that ran to a manifold and connected to all of the solenoid valves. The plugs allowed pressure to build up behind them and caused the brake calibers to open. As the brakes unset, the draw works dropped about twenty feet before the crew was able to activate the emergency hydraulic dumps.

The investigation that followed the third incident showed that the cause of the excessive heating was due to the crew improperly installing a hydraulic pump on the braking system. Although the mistake was caught and the pump installed correctly, damages to the pump were sustained that the crew was unaware of. The pump was overheating and causing the system fluid to overheat as well.

The following two incidents occurred after the June 9 incident, while the crews were troubleshooting the system attempting to identify the causes:

On June 25, 2014, while trouble shooting the draw works system, the rig experienced yet another uncontrolled decent of top drive. The crew had received a brake caliper alarm and pulled the emergency hydraulic dump as a precaution to ensure the breaks were set before turning the system off to investigate the problem. The hydraulic dump was reset and when the crew switched the draw works system back on, the brake calipers all opened causing the traveling block to descend approximately 7 feet until being caught by the drill string. By resetting the hydraulic dumps, which were keeping the brakes engaged, and failing to command the top drive motors to take control, the load was left unsupported and allowed to fall.

The investigation following the second incident discovered that the brake issues were caused due to the sticking of the hydraulic solenoid valves. These valves provide pilot pressure to the brake calipers. After extensive testing, it was found that the valves were only sticking after being left in the open position for an extended period of time. Reports from Stress Engineering Services concluded that "the debris in the valves was of sufficient size and quantity to cause the sticking of these valves". It was determined that the same situation had triggered the brake alarm during the first incident.

SPECIFY VIOLATIONS DIRECTLY OR INDIRECTLY CONTRIBUTING. NARRATIVE:

A G-110 INC issued following the investigation states:

"On June 9, 2014, the Transocean Deepwater Nautilus experienced an uncontrolled decent of the traveling block and top drive due to a fault in the draw works system. The incident endangered personnel and led to extensive damage to equipment on the rig floor. The incident occurred while the rig crew was troubleshooting a fault alarm that was received during operations. The crew proceeded to reset the system without first identifying the cause of the alarm or ensuring that it was safe to do so."

ACCIDENT INVESTIGATION REPORT – OIL RELEASE FROM HEATER-TREATER BY FAILING TO DEPRESSURIZE THE VESSEL

ACCIDENT INVESTIGATION REPORT – OIL RELEASE FROM HEATER-TREATER BY FAILING TO DEPRESSURIZE THE VESSEL

On June 23, 2014, an incident occurred at approximately 10:30 A.M. on the Arena Offshore East Cameron 328 B facility which resulted in a pollution event and injury to an operator (injured person or IP).  The IP was also the platform's Person in Charge (PIC).  At the time of the incident, the IP was attempting to replace the pneumatic temperature controller (TC) on Heater Treater #2 NBK-2770 (vessel).  The TC was threaded directly into a thread-o-let within the liquid medium of the vessel instead of being installed inside a thermo-well as recommended by the manufacturer.  The vessel normally operates at approximately 40 pounds per square inch (psi) and 150 degrees Fahrenheit.  There were six persons on board the facility, including one Field Foreman, four Operators, and one Electrician.

On June 24, 2014, the BSEE Lake Charles District conducted an onsite accident investigation and learned that operations personnel experienced problems with the vessel's TC maintaining a stabilized temperature on June 22, 2014.  As a result of the temperature instability, the vessel's liquid medium temperature safety high (TSH) sensor activated a shut-in action of fuel and inflow of fluids.  Again on June 23, 2014, the vessel's TSH activated due to temperature instability and operations personnel deemed it necessary to replace the faulty TC. Approximately two hours after the TSH activated, with the vessel's heat source shutdown and the liquid inlets and outlets blocked off, the IP began removing the TC.  

However, the vessel was not depressurized and the hot oil was not drained to a safe level below the TC. Once the TC was completely removed from the thread-o-let, hot pressurized oil blew out of the one inch opening in the vessel, striking and burning the IP on his left bicep. Operations personnel then shut-in the rest of the facility by manually actuating an emergency shut-down station.  Oil continued to flow out of the one inch thread-o-let, striking the line heater approximately 20 f􀁆􀁆t across the deck.  In an effort to direct the oil into the containment skid beneath the vessel, operations personnel positioned a sheet of plywood in front of the oil stream. Once the pressurized flow of oil declined, operations personnel installed a one inch nipple and ball valve into the open thread-o-let, isolating the leak. After regaining control of the vessel, operations personnel reported the pollution event (National Response Center Incident Report # 1086799) and made arrangements for the injured operator to be evacuated.

Personnel then cleaned themselves up due to being covered in oil, and then began cleaning the facility. A Spill Report Form was submitted showing that 12 gallons of crude oil were discharged into offshore waters and one person sustained a burn injury to his arm due to the incident.

The BSEE investigation findings revealed that the operations personnel took the following precautionary measures in preparation for replacement of the TC: manually blocked the boarding valve on the Vermillion 342 A incoming pipeline, isolated the vessel's liquid dump lines, and isolated the make-up gas to the vessel. The Job Safety Analysis (JSA) for this task identified hazards, including: pressure, temperature, and liquid release; however, the JSA failed to specifically identify the primary potential threat which was the TC not being installed inside a thermo-well.

As a result, critical mitigations were not executed prior to removing the TC from the vessel which jeopardized the safety of personnel, production equipment, and the environment.  These critical mitigations included: depressurizing the vessel, lowering the liquid levels within the vessel, and allowing sufficient time for cooling.

LIST THE PROBABLE CAUSE(S) OF ACCIDENT:

The IP removed the TC prior to depressurizing and lowering the oil level within the vessel.

LIST THE CONTRIBUTING CAUSE(S) OF ACCIDENT:

Operations personnel failed to recognize the potential hazards associated with the TC being installed directly into the vessel instead of inside a thermo-well; therefore adequate mitigations were not identified on the JSA and implemented prior to performing the TC replacement.

SPECIFY VIOLATIONS DIRECTLY OR INDIRECTLY CONTRIBUTING. NARRATIVE:

E-100 A pollution event occurred on June 23, 2014, discharging 12.3 gallons of crude oil into the Gulf of Mexico, during an incident involving the NBK-2770 Heater Treater.

G-110 Operations personnel failed to conduct operations in a safe and workmanlike manner which resulted in injury to the PIC and uncontrolled flow of oil into offshore waters on June 23, 2014.

OIL & GAS ACCIDENT INVESTIGATION REPORT – FAILURE TO REPAIR LEAKING VALVES – BLACK ELK ENERGY

OIL & GAS ACCIDENT INVESTIGATION REPORT – FAILURE TO REPAIR LEAKING VALVES – BLACK ELK ENERGY

OPERATOR: Black Elk Energy Offshore Operations

This was an incident during development/production (DOCD/POD).

On July 4, 2014 at 1300 hours, Construction Workers on the Main deck of the platform were preparing to resume hot work when they heard an unusual noise from the deck below (Cellar Deck). Stop Work Authority (SWA) was initiated and the Lead Operator and Contract Safety Representative went to the source of the noise which was the well bay area on the Cellar Deck. Natural Gas was observed to be leaking from the upstream flange of the Flow Safety Valve (FSV) on the FA-2 flow line segment on the B-001 well upstream of the production header. The construction crew was instructed to muster at the boat landing (+10) and board the stand-by boat. The Lead Operator and Contract Safety Representative remained on the facility to attempt to isolate the B-001 well which was unsuccessful. 

The Lead Operator bled pressure off the FA-2 flow line segment every two hours to mitigate natural gas leakage from the upstream flange of the FSV. It was determined that the Manual Master Valve and Surface Safety Valve on the Wellhead were leaking due to the B-001 well having a history of making traces of sand. Additionally, the Wing Valve on the FA-1 flow line segment was leaking therefore allowing the Shut in Tubing Pressure (SITP) of 3200 Pounds per Square Inch Gauge (PSIG) to be present up to the Out of Service production header causing a gasket failure on the upstream flange of the FSV. During the Investigation it was identified that the Management of Black Elk Energy failed to mitigate valve deficiencies that were previously identified on August 16, 2013. The FA-2 flow line segment was removed and blind flanges were installed on July 5, 2014

LIST THE PROBABLE CAUSE(S) OF ACCIDENT:

The Manual Master Valve, Surface Safety Valve and Wing Valve were leaking which allowed the Shut in Tubing Pressure of 3200 Pounds per Square Inch Gauge (PSIG) to be present up to the Out of Service production header causing a gasket failure on the FSV.

LIST THE CONTRIBUTING CAUSE(S) OF ACCIDENT:

The B-001 well had a history of making traces of sand.  Management failed to mitigate valve deficiencies that were previously identified on August 16, 2013.

The date of last production on the B-001 well was August 2013.  This unmanned facility and has been shut in since October 5, 2013.

SPECIFY VIOLATIONS DIRECTLY OR INDIRECTLY CONTRIBUTING. NARRATIVE:

G-110 'C' 30 CFR 250.107(a): Black Elk Energy failed to follow up and repair valves on the B-001 well that were known to be leaking since August 16, 2013.  Civil Penalty will be evaluated.

OIL PLATFORM ACCIDENT INVESTIGATION – OVER-PRESSURIZATION OF THE WELL ANNULUS

OIL PLATFORM ACCIDENT INVESTIGATION – OVER-PRESSURIZATION OF THE WELL ANNULUS

On August 17, 2014, an incident occurred that resulted in significant damage to the lower annular. This was an exploratory drilling operation.  The lower annular operating chamber was prepared for pressure testing on the surface. The target pressure for this test was 3000 psi. Once the lower annular was prepared, the Subsea Engineer started applying pressure to the operating chamber using a test pump. At this time, with the pump still running the Subsea Engineer decided to put away some tools, leaving the test pump unit unmanned. 

The Subsea Supervisor arrived at the test unit to find the test pump unattended. He then left the testing area to look for the other Subsea Engineer. He found the Subsea Engineer in their shop and informed him that the test pump should never be left unattended. The Task Based Risk Assessment did not address the monitoring of the running pump. The Subsea Supervisor also informed the crew they should be testing the upper annular operating chamber and not the lower annular operating chamber. 

At this time a loud bang was heard coming from the testing area and the test pump was then immediately shut down. Further investigation by rig personnel found that the lower annular operating chamber that has a (MAWP) Maximum Allowable Working Pressure of 3000 psi, was overpressurized to at least 10,000 psi.

LIST THE PROBABLE CAUSE(S) OF ACCIDENT:

1)    Poor communication between all personnel involved in the testing procedure.

2)    Leaving the test pump running while unattended allowing the component being tested to over pressurize.

3)    Nothing notated in the Task Based Risk Assessment about leaving the test pump running without properly trained personnel monitoring the pressure.

4)    The Subsea Supervisor failed to secure the test pump prior addressing the Subsea Engineer about leaving pump running and unattended.

LIST THE CONTRIBUTING CAUSE(S) OF ACCIDENT:

1)    Miscommunication and not being focused on the task at hand.

2)    Initial documentation showed the upper annular operating chamber should have been tested and not the lower annular operating chamber.

3)   Not double-checking with Subsea Supervisor prior to commencing testing.

DAMAGED PROPERTY

Lower Annular

COST OF DAMAGE

Sheared inner cylinder studs. Pusher plate blown out of annular housing.  Broken shuttle valve on choke isolation valve.  Also support ring and inner piston dislodged due to over pressurization causing significant damage to lower annular.

Sevan Drilling has been forced to halt operations on a well being drilled in the Gulf of Mexico due to a technical glitch with newbuild cylindrical rig Sevan Louisiana.