Downstream & beyond: Decommissioning Flashcards
What is decommissioning?
Decommissioning is the process of “closing down” an oil rig after production processes have ended.
Decommissioning is a rapidly developing area of the oil & gas sector with many risks
Decommissioning steps
- Permits & regulatory compliance
- Hydrocarbon purge & flush
- Plug & abandon
- Topside decommission (dismantle)
- Structure removal (or not?)
- site clean up
- monitoring and surveying
Why are rigs decommissioned?
Oil rigs not used in 5 years or more are typically decommissioned
- Idle structures could be damaged (during environmental disasters)
- Damaged platforms and wells are more costly to decommission than non-damaged ones
10 Detailed Steps in Decommissions
- Project Management, Engineering, and Planning
- Permitting and Regulatory Compliance
- Platform Preparation
- Well Plugging and Abandonment
- Conductor Removal
- Mobilization and Demobilization of Derrick Barges
- Platform Removal
- Pipeline and Power Cable Decommissioning
- Materials Disposal
- Site Clearance
Project Management
Feasibility studies are conducted to determine the best, most cost-effective, safest approach
The planning for decommission starts 3 years in advanced before well runs dry
Involves:
- Review of contractual obligations
- Engineering analysis
- Operational planning
- Contracting
Permitting & Regulatory Compliance
Local consulting firms are typically hired to ensure all permits are in order before decommission since they know the laws and regulations in the region.
Permitting & Regulatory Compliance
Execution Plan is one of the ……………. steps in the process. it includes:
first
- Environmental info & field surveys of site
- Schedule of decommission activities
- Equipment needed
- Labor needed
The Execution Plan is needed for these reasons:
- •To get regulatory permits
- •Assess & reduce environmental impact
Hydrocarbon Purge & Flush
To prepare for decommissioning, everything must be cleaned!
The Purge Includes:
- Cleaning:
- Tanks
- Processing equipment
- Piping
- Disposal of residual hydrocarbons
- Removal of platform equipment, including:
- Cutting pipes & cables
- Separating modules
- Installing padeyesto lift modules
- Reinforcing the structure
Well Plugging & Abandonment
- This stage is one of the most expensive aspects of decommissions
- Plugs must be tagged for proper placement, or pressure-tested for integrity
- includes two phases:
- the planning phase
- well abandonment phase
The Planning Phase
- •Data collection
- •Preliminary inspection
- •Selection of abandonment methods
- •Submittal of application for government approval
Well Abandonment Phase
- Well entry preparations
- Filling the well w/fluid
- Removal of downhole equipment
- Cleaning out wellbore
- Plugging:
- Open-hole
- Casing stubs
- Annular space
- Surface plug
- Fluid between plugs
the well plug and adandonment process includes the following stages:
- perforating casing to facilitate water circulation
- injecting cement plug to create intermediate bariier
- cutting and recover surface casing strings
- inserting packer and injecting cement to create environmental barrier.
Topside Decommission
Platform components & conductor casings must be removed at least 15ft below the ocean floor.
there are three methods for conductor casing removal
