Equipment
Wellhead
Equipment at the well surface providing pressure containment and access.
Documents
- 202631 Mar
Source control planning and procedures information paper
This information paper sets out regulatory expectations for offshore loss-of-well-control preparedness across environment plans, well operations management plans and safety cases. It covers capping-stack selection and deployment, relief-well design and dynamic kill analysis, plume modelling, subsea dispersant supply, water-column monitoring, response-time modelling, coordinated operations and readiness exercises.
- 2026Feb
Well Workover
This regulatory inspection guide presents compliance questions for oil and gas well-workover operations. It covers prior approval, well-control fluid replenishment and measurement, crown-block safety checks, mud-pit level warnings, tubing and wellhead requirements, wireline leakage prevention, and pressure testing of newly installed lubricators against expected shut-in surface pressure.
- 2026Jan
D-PINCs (Operators Version - Jan 2026) — Drilling
A regulatory checklist for oil and gas drilling, linking numbered compliance questions to statutory authorities and enforcement actions. It addresses approvals, diverter configuration and testing, casing installation, cement placement, drilling-fluid management and monitoring. Further checks cover ventilation, gas detection, ignition prevention and retention of drilling and test records.
- 2026Jan
Well Operations
An inspection guide presenting compliance questions for well operations under Subpart G, with regulatory authorities and enforcement codes. It covers casing and liner integrity, surface and subsea blowout preventer configuration, pressure and function testing, maintenance and records, alongside specific requirements for coiled tubing and snubbing systems.
- 202430 May
2024-01 64 Investigation of March 25, 2022, Hydraulic Workover Unit Failure Fatality
BSEE investigates a fatal hydraulic workover unit collapse at Main Pass Block 64 Platform #19. Severely corroded structural casing buckled after crane support was removed, and a worker tied to the unit was pulled into the water. Findings examine load assessment, Anchor Spool stabilisation, oversized equipment and unclear operator–contractor responsibilities.
- 202326 Dec
Wendland 1H Well Fatal Explosion
CSB investigates a fatal blowout and fire during tubing-head replacement at a Texas oil and gas well. It analyses inadequate well-control planning, ineffective hydrostatic and valve barriers, and ignition-source management. Recommendations address workover methods for underpressured reservoirs, well-history review and gaps in industry guidance and federal regulation.
- 202225 Feb
Jacking Up Lift Boat During Crane Operations
During well abandonment, a lift boat was raised with crane slings still connected to a wellhead. Suspected snagging on hanger pins preceded sling failure and injury to an operator. BSEE recommends considering interface disconnection, attentive crane operation, elevation-adjustment procedures and job safety analysis addressing interconnected equipment.
- 201913 Aug
Safety Alert 364 - Improper Riser Tension Leads to Subsea BOP Falling Off Wellhead Mandrel and Failure of Riser Adapter
A subsea BOP tilted during disconnection after insufficient riser tension overloaded its adapter, which subsequently failed, leaving the BOP on the seafloor. The well had been plugged and no pollution occurred. BSEE recommends considering calculated unlatching procedures, tension verification hold points, safe operating parameters and renewed risk assessments for well-to-well BOP moves.
- 201819 Sep
Well Integrity (Operate Phase)
Inspection guidance for assessing well integrity during operation through management-system document review and role-specific interviews. It examines barrier verification, annulus pressures, operating and load limits, maintenance, change management and end-of-life review. Optional risk-assessment scrutiny covers qualitative assessment, QRA and FMECA, while enforcement guidance links inspection findings to compliance scoring.
- 20176 Jul
Well annulus leaks gas-lift inventory from failed instrument line
An instrument tubing failure released production-annulus hydrocarbon gas for 3.5 hours. Its position between the wellhead and gas-lift shutdown valve prevented shutdown from isolating the annulus inventory. The alert discusses small-bore integrity, secondary barrier vulnerability, two-barrier practice and recommended shutdown-valve placement and activation.
- 20173 Jul
Environmental Alert 001/2017
This alert examines capping-stack deployment where a 15,000 psi BOP contains a lower-stack annular preventer rated to 10,000 psi. For the described HPHT blowout configuration, it identifies the wellhead connector, after lower BOP removal, as the only attachment position tested to 15,000 psi, and requires consideration in oil-pollution emergency response strategies.
- 201524 Feb
Safety Alert 315 - Dynamic Positioning System Failures on Offshore Supply Vessels Engaged in Oil and Gas Operations
Joint Coast Guard and BSEE alert examines an offshore supply vessel losing position during wireline plug removal, shearing a wellhead tree through connected high-pressure lines and releasing lubricant. It discusses ignored DP failures, emergency disconnect capability, DP equipment classes, activity-specific guidance, personnel competence and leaseholder oversight of contracted vessels.
- 201510 Feb
Environmental Assessment
Draft environmental assessment comparing proposed Arctic exploratory drilling rules with alternatives, including no action. It examines pollution prevention, blowout-preventer testing, well monitoring, containment equipment and relief-rig availability in the Beaufort and Chukchi Seas. Analysis considers potential spill consequences, marine wildlife, subsistence practices and additional operational effects.
- 201231 Jan
Safety Alert 299 - Failure to Properly Bleed Tubing Hanger Void Results in Injury
During wellhead dismantling for temporary abandonment, trapped hydraulic pressure ejected a tubing hanger pin and packing nut, striking a worker’s shin. The alert identifies installation defects, unchecked void pressure and shortcomings in supervision and hazard analysis. Recommendations address bleed-down verification, training, personnel positioning and use of a backup wrench.
- 200928 Jan
Safety Alert 275 - Wellhead Damage Caused by Hurricane
Following Hurricane Ike, damaged flanged wellhead connections leaked, and one subsurface safety valve initially failed to isolate downhole pressure. The alert examines hurricane loading and failed supports, and recommends visual inspection before restarting wells, followed by isolation, repair and wellhead pressure testing where excessive loading is suspected.
- 2008Nov
2008-054 Investigation of Loss of Well Control, South Pelto Block 10, Well No. 10, OCS-G02925, 14 February 2008, Gulf of Mexico off the Louisiana Coast..
Investigates natural-gas release during wireline scale removal and acid treatment at South Pelto Well No. 10. The panel identified ring-gasket corrosion, likely acceleration by acid treatment and an inoperable subsurface safety valve prolonging the event. It examines wellhead testing, integrity inspections and platform evacuation, recommending reviews of acid-operation policies and emergency plans.
- 20051 May
Inadvertent Unlatching of Wellhead Connector
A semi-submersible inadvertently unlatched a subsea wellhead connector on a recently perforated well. Differential pressure separated the stack and broke the seal, allowing riser fluid levels to equalise with seawater pressure. Reduced hydrostatic pressure permitted crude oil influx; prompt relatching restored the seal and averted a catastrophic well-control and environmental situation.
- 200518 Feb
Safety Alert 18 - Well-Control Equipment Circumvention
An MMS alert describes loss of well control during workover/completion after completion-fluid pumping stopped and a tubing hanger lockdown pin was removed, bypassing blowout prevention. Seawater and hydrocarbons escaped. It distinguishes direct from possible contributing causes and recommends improved hanger-landing procedures, well-control training and job safety analyses.
- 200429 Nov
Safety Alert 223 - Loss of Well Control
A workover involving nitrogen washing removed a sand bridge from a well shut in for approximately ten years. Gas escaped through a corroded wellhead injection port where a seal assembly was absent, causing a minor condensate spill. The alert recommends reviewing maintenance and improving written instructions and job safety analysis.
- 200424 Jun
Safety Alert 221 - Hanger Failure and Ejection Lead to Well Control Incident
During a workover, hanger hold-down pins sheared at 6,150 psi, ejecting the hanger and tubing. Investigation identified inadequate pin engagement caused by a design flaw. The alert identifies affected Cameron products, recommends multiple well barriers and advises operators to consider shear rams for wells presenting unusual control problems.
- 20036 Oct
Safety Alert 215 - Diving Fatality
A diver died in an explosion while torch-cutting casing during well abandonment. MMS attributed ignition to a cinder carried in an air bubble reaching accumulated hydrogen above adaptor vent holes. The alert highlights inaccurate configuration information and absent task-specific JSA, recommending reviews of contractor information transfer and management of unexpected conditions.
- 200115 Nov
Safety Alert 199 - Blowout and Fire
An alert describes a shallow-gas blowout during slip-on wellhead welding, unsuccessful attempts to kill the well with increasingly dense fluids, evacuation and a subsequent fire of unknown origin. Investigation identified inadequate cement design and communication failures. Recommendations address gas migration prevention, contractor communication and use of well-log information.
- 198518 Jun
Safety Alert 140 - Uncontrolled Well Flow and Pollution During Workover Operations
During reperforating, leaking casing hanger anchor screws were removed without securing the well, leading to uncontrolled flow and approximately 50 barrels of pollution. The platform was evacuated. The alert reiterates requirements for qualified, certified repair personnel, separation from downhole operations and management approval of procedures for repairs to unsecured wells.
- 197929 Dec
Safety Alert 93 - Flowline Parts, Injury
A pumper suffered head injuries while restarting offshore well production. Pressure against a closed header valve ruptured a flowline weakened by carbon dioxide corrosion; flying debris or impact against an object was reported. The operator’s measures included X-ray, density-meter and visual inspections, corrosion inhibitor injection and replacement with corrosion-resistant alloy steel.
- 19785 Sep
Safety Alert 73 - Gas Leak from Subsea BOP Stack While Circulating Out Kick
A semisubmersible rig was evacuated after gas escaped from its subsea BOP stack during kick circulation. A non-conforming ring gasket failed to seal, and escaping fluids damaged a hydraulic line, preventing BOP operation and riser release. The alert records the operator’s planned gasket quality controls and flange-standoff verification procedures.
- Undated
Well-Control Event and Hydrocarbon Spill During Coiled Tubing Work
BSEE investigates a well-control and pollution event at West Delta 80 D during coiled tubing work. The report examines tubing-to-casing communication, probable corrosion-related alignment pin plug failure, delayed remediation and reporting, and inadequate fluid-handling capacity. An estimated 107 gallons of hydrocarbons spilled; all 19 personnel evacuated without injury.
- Undated
Riser Adapter Fails During Disconnection and BOP Stack Falls to Seabed
BSEE investigates a riser adapter failure during disconnection following temporary well abandonment. Reduced riser tension allowed the BOP stack to tilt and subsequently fall to the seabed. Finite element analysis supported the failure explanation. Findings identify inadequate procedures and undefined safe operating parameters; the plugged well caused no attributed pollution.
- Undated
Tool-String Ejection During Temporary Well Abandonment
BSEE investigates a tool-string ejection during temporary abandonment of the E-4 well at Ship Shoal 224 E. Firing an electric-line casing cutter released trapped annular pressure beneath a subsea tieback wellhead, damaging deck grating without reported injuries. Findings address unrecognised pressure communication restrictions, absent wireline pressure control and planned procedural changes.
- Undated
Wellhead Releases Mud, Water and Cement During Annular Cement Squeezing
Investigation of a wellhead release during annular cement squeezing on Diamond Ocean Champion. A lock-down dog failed or became unscrewed, releasing mud, water and cement. The narrative describes evacuation and subsequent well securing, and records proposed wellhead checks, pressure testing and cementing measures. The attachment contradicts the narrative on evacuation.
- Undated
Accidental BOP Wellhead Disconnect During Completion Operations
Investigation of an accidental BOP wellhead disconnect on Ocean Saratoga during completion operations. Crossed Yellow Pod hoses, deficient procedures and missed verification opportunities allowed the fault to remain undetected. The incident released calcium bromide completion fluid. Contractor directives address dual-pod testing, connector verification, competence and communications.
- Undated
Shallow Water Flow from Wellhead Cement Port During Riserless Drilling
BSEE investigates shallow water flow from a wellhead cement port during riserless drilling at Garden Banks Block 962. Fluid analysis detected limited hydrocarbons. Logging and ROV monitoring examined cement channelling; investigators identified salt contamination as the probable cause. Shell subsequently decided to temporarily abandon the well.
- Undated
Gas-Pressure Release During Tree-Cap Flange Replacement
Investigation of a gas-pressure release during tree-cap flange replacement on well A-15 at Vermilion 369 Alpha. A contractor sustained eye and facial exposure and required medical evacuation. Findings identify inadequate lockout/tagout, missing written isolation instructions, limited platform-specific operator experience and unsuitable working surfaces affecting body positioning.
- Undated
Loss of Well Control During Plug and Abandonment
BSEE investigates a well-control loss during plug and abandonment at West Delta 90 B. An estimated 20 barrels of well fluids escaped, followed by uncontrolled gas and evacuation. Findings identify a spooling-head breach, tubing communication and deficient use of historical well information; the precise origin of the tubing failure remains unresolved.
- Undated
Zinc Bromide Brine Discharge During Casing and Blowout Preventer Refilling
Investigation of a zinc bromide brine discharge during refilling of production casing and a blowout preventer on Enterprise 264. Investigators used interviews, written statements and recorded pit volumes to revise the loss estimate to approximately 79 barrels. The report identifies incomplete casing valve closure and limited visibility during pumping.
- Undated
Loss of Well Control During Temporary Abandonment
Investigation of lost well control during temporary abandonment of the B002 well at Ship Shoal 225. Pulling a plug without checking pressure beneath it preceded hydrocarbon escape through leaking tubing and casings. The report examines deficient records review, testing, procedure changes, site-specific hazard analysis and supervision, and recommends stronger abandonment controls.
- Undated
Synthetic-Based Mud Leak During Casing Pack-Off and Wellhead Connection Testing
The investigation documents a total loss of 20 barrels of synthetic-based mud during casing pack-off and wellhead connection testing. ROV observations and surface inspection identified leakage and washed seal areas. The report attributes the leak to a hydrate seal interfering with metal-to-metal sealing and records no recommendations for the regional safety office.
- Undated
Workstring Ejection During Tubing Cutting
Investigation of a workstring ejection during tubing cutting at VR 398 Well A002. Sand and wireline debris obstructed the DX plug’s equalising ports, while a leaking overshot packoff gave a false indication of pressure equalisation. Blowout preventer closure controlled the well; the report records equipment damage and recommends a safety alert.
- Undated
Finger Trapped by Bolt During BOP Installation
An investigation examines a finger fracture during BOP installation for well abandonment at ST. 26-D. While the crane lowered the assembly, a misaligned bolt moved upwards and trapped the worker’s finger. The report identifies hazardous hand placement and discusses slippery gloves and simultaneous alignment of twelve bolts as possible contributors.
- Undated
Condensate and Gas Release Beneath Hurricane-Toppled Platform
Investigation of a condensate and gas release from Well C-9 beneath a platform toppled by Hurricane Ike. The report examines a broken master valve, uncertain subsurface barrier failures and a proposed trapped hydraulic-pressure mechanism. It describes limited condensate recovery, valve replacement and cement squeezing to secure the well.
- Undated
Gas Release and Surface Casing Collapse During Well Abandonment
BSEE investigates a gas release during well abandonment on South Marsh Island Block 281C. Corrosion and loss of conductor casing led to surface casing collapse at Well C-11, damaging valves and decking. The report describes evacuation, well securing and subsequent abandonment, and records noncompliance with immediate incident-notification requirements.
- Undated
Unsecured Wellhead Rolled onto Supervisor During Well Abandonment
BSEE investigates a leg injury during permanent well abandonment at Eugene Island 158JB. An unsecured wellhead rolled onto a supervisor on a lift boat’s deck. The report examines inadequate storage, stability checks and job safety analysis, describes crane-assisted rescue and medical evacuation, and records Apache’s corrective action to provide a scrap basket.
- Undated
Ejected Wireline Tool String Struck Worker During Well Abandonment
Investigation of an injury during well abandonment when a wireline tool string and night cap were ejected approximately 100 feet into the air. The tool string struck a worker. Findings identify unrecognised trapped pressure and deficiencies in management of change, stop-work intervention and job safety analysis.
- Undated
Hydrocarbon Release During Casing Cutting for Subsea Well Abandonment
Investigation of hydrocarbon leakage during abandonment of a temporarily abandoned subsea well in the Gulf of Mexico. Cutting casing strings released trapped annular gas and liquid hydrocarbons. The report describes spill response, a pollution dome, remedial cement plugging and subsequent clearance, and identifies primary casing cement as the only annular barriers.
- Undated
Vessel Lost Station Keeping and Severed Production Tree During Wireline Operations
Investigation of Endurance’s loss of station keeping during wireline operations at Eugene Island 355A. Vessel movement severed the production tree through connected rigid pipework, causing an oil spill and deck damage without reported injuries. Suspected communications-tower interference and absent emergency disconnection are examined, alongside equipment-separation measures and proposed vessel evaluation procedures.
- Undated
Vessel Collision Sheared Wellhead and Ruptured Gas Lift Line
An unidentified vessel struck Chevron’s satellite well structure No. 138, shearing the wellhead and rupturing a gas lift line. Dry gas escaped, with no injuries or pollution reported. The investigation attributed the collision probably to loss of vessel control; weather and navigational-aid performance remained undetermined.
- Undated
Tubing Hanger Pin Ejection During Temporary Well Abandonment
Investigation of a tubing hanger pin ejection during temporary well abandonment, causing a fractured shin. A defective fitting allowed hydraulic fluid into a wellhead void, compressing trapped air or gas. Findings address unrelieved pressure, improper pin removal, unavailable tools, supervisory training oversight and incomplete job safety analysis.
- Undated
Flash Fire During Torch Cutting of Tubing-Hanger Flange Nut
An investigation describes a flash fire during preparation of a well for a sidetrack. Torch cutting of a stubborn tubing-hanger flange nut released trapped gas despite a hot-work permit, gas testing and a fire watch. One worker suffered a neck rash, received burn cream and returned to work.
- Undated
Wellhead Gas Leaks During Production Restoration After Hurricane
Investigation of wellhead gas leaks during restoration of platform production after Hurricane Ike. Stretched flange studs compromised seals, while Well G-4’s SCSSV initially failed to seal. The report describes flaring, component replacement and testing, and recommends post-event inspections, isolation and wellhead pressure tests before reopening SCSSVs.
- Undated
Condensate Release During Plug and Abandonment and Salvage Operations
Investigation of a condensate pollution event during plug and abandonment and salvage operations at Grand Isle Block 47. The report attributes the release to wellhead mechanical failure, rather than the initially reported impact. It records containment attempts, wellhead installation and testing, subsequent annulus leakage, and differing spill-volume estimates.
- Undated
Ejected Master Valve Stem Injures Contractor During Temporary Well Abandonment
Investigation of a manual master valve failure during temporary well abandonment at EI 252-G. An ejected valve stem struck a contractor’s hand, fracturing his thumb tip. Personnel were evacuated because well stability was unknown. Findings address a missing retainer nut, valve servicing, contractor oversight and management of change.
- Undated
Hydrocarbon Release During Well Workover and Completion
Investigation of a well-control incident during workover and completion on Platform Gail. Removal of a wellhead lockdown pin bypassed the BOP system, while discontinued fluid pumping allowed an underbalanced condition. The report describes hydrocarbon release, hydrogen sulphide readings, evacuation and an approximately three-gallon oil spill, with recommendations on well-control practices and training.
- Undated
Loss of Well Control and Oil-Based Mud Spill from Wellhead
An investigation records loss of well control and mineral oil-based mud spilling into the Gulf after a packing gland nut and hold-down pin were forced from a wellhead flange. It identifies inadequate training and contributing well-operation failures, and recommends designated personnel trained for wellhead work.
- Undated
Gas Leakage from Master-Valve Flange During Platform Renovation
An investigation examines gas leakage from a well’s master-valve flange during platform renovation. Findings suggest installation over-torque weakened two bolts, with high-sea motion believed to contribute to failure. A closed subsurface safety valve limited the release. Personnel evacuated by boat before specialist repairs; no injuries or pollution were reported.
- Undated
Oil Release from Permanently Abandoned Subsea Well
Investigation of an oil release from a permanently abandoned subsea well in the Gulf of Mexico examines drilling, cement placement, plug verification and delayed well-control response. The specific cause remained unresolved because deeper plugs could not be reached. Findings identify possible contributing factors and propose research and regulatory changes.
- Undated
Engineered Safety and Environmental Aspects of Well Construction and Fracturing Design
Presentation on engineering well construction and hydraulic fracturing for pressure containment and groundwater protection. It covers casing and liner design, cement evaluation, treating-line ratings and testing, staged pump shutdowns, relief arrangements and wellhead valves. Surface planning addresses fluid storage, spill berms and logistics, alongside examples of fracturing-fluid ingredients.