Pipeline Decommissioning Process in Oil and Gas
Oil and gas pipelines are the primary media used to transfer products from a refinery to the final consumers. Extensive networks of steel tubes move hydrocarbons at high speed between multiple locations in the country and to other parts of the world on a daily basis.
However, all commercial activities must come to an end. Decommissioning is an essential phase every oil and gas operator must plan for well ahead of time to ensure a cost-effective transition and compliance with applicable regulatory provisions.
What Is Decommissioning in Oil and Gas?
Decommissioning in oil and gas refers to the termination of hydrocarbon exploration, production and supply efforts in an area. In practical terms, it involves plugging and abandonment of the drilled hole and disposal or sale of production and supply assets.
Oil & gas decommissioning is usually done when production drops below economically viable levels, and all EOR efforts have been exhausted.
What Is Pipeline Decommissioning?
Pipeline decommissioning is the termination of all oil and gas transport through a pipeline at the end of its economic life or at the conclusion of oil and gas supply in the areas it serves. Decommissioning of pipelines requires adequate planning, manpower, and resources in line with local land use and environmental regulations.
Why Is Pipeline Decommissioning Necessary?
To supply oil and gas for further processing or to the final consumers, operators will lay several miles of pipeline over vast expanses of land or sea. Over time, the operator might need to create a new network in the same right of way as the existing pipelines. Thus, the operator retires the older lines at the site or removes them.
Whose Responsibility Is Pipeline Decommissioning?
Pipeline operators and owners are responsible for operating and retiring their pipelines in a manner that respects the health and safety of citizens in the immediate locality. The Federal Energy Regulatory Commission (FERC) is the body responsible for regulating pipeline usage and decommissioning in the U.S.
Before decommissioning a line, a comprehensive engineering and environmental impact assessment are carried out by the operating company. The regulatory authority for the area then approves a suitable decommissioning procedure based on the results of the evaluation.
The pipeline decommissioning process could be either pipeline removal or abandonment.
Oil Rig Decommissioning Process
The Oil and gas decommissioning process at offshore/onshore rigs are the series of steps taken to put pipelines out of use at these locations. The main techniques used are abandonment or pipeline recovery.
The following are the key steps involved:
- Project management
- Permitting and regulatory compliance
- Platform Preparation
- Well Plugging and Abandonment
- Conductor removal
- Mobilization/Demobilization and Platform Removal
Pipeline Removal vs. Pipeline Abandonment Procedure
There are two main ways for retiring pipelines – burying them in place (abandonment) or pipeline recovery from the site. FERC regulations require operators to remove defunct pipelines (pipelines out of use for many years) if leaving them in place poses any health, safety, or environmental hazards or interferes with fishing, navigation, land, or sea use.
Pipeline abandonment (in-place decommissioning) is the most common procedure for the vast numbers of pipelines located in the U.S. and Gulf of Mexico.
In-place retirement of pipelines hold some benefits over complete removal. It prevents extensive excavation of land (for buried pipelines), minimizes the inherent safety and environmental hazards and disruption of surrounding ecosystems.
Types of Pipeline Decommissioning
Pipeline decommissioning in the oil and gas industry depends on pipeline type, location, type of process fluid etc. In the oil and gas industry, the following types of pipelines are decommissioned:
- Onshore pipelines
- Offshore pipelines
- Subsea pipelines
These lines transport hydrocarbons petroleum, natural gas, or natural gas liquids (NGL) from production locations or a refinery to consumers.
Onshore Pipeline Decommissioning Procedure
Decommissioning at onshore locations involves retiring land-based pipelines above or below the earth surface.
The process typically involves the following steps:
- Flushing out any remaining oil and gas from the pipeline (consider nitrogen purging)
- Cleaning the pipeline with special devices called pigs
- Physical separation of the pipeline from the supply
- In-place abandonment or recovery of the newly decommissioned pipeline
*Oil and gas pigs can be used to flush the interior of oil and gas pipelines prior to decommissioning. The pig is a cylindrical or spherical device propelled through a pipeline by the force of the fluid in motion or pulled with a string.
Subsea Pipeline Decommissioning Process
Subsea decommissioning involves retiring pipelines located in ultra-deepwater wells and remote locations.
Subsea pipelines are generally decommissioned in three ways:
- Preservation in place for future use
- Pipeline recovery (which is an expensive process)
- In-situ pipeline retirement
In the U.S., subsea decommission is covered under the CFR (Code of Federal Regulation) Part 250, Sub-part Q  and administered by the Bureau of Safety and Environmental Enforcement (BSEE).
For decommissioning efforts in ultra-deepwater wells and remote locations, health and safety standards are of paramount importance.
Oil Rig Decommissioning Process
Oil rig decommissioning involves pipeline removal or abandonment at rig locations which could be offshore or land-based. Pipeline and oil rig decommissioning companies offer consultancy services to help operators put their oil and gas pipelines out of use safely and efficiently. If you’re searching for reliable pipeline maintenance companies, consider NiGen.
Use NiGen’s Pipeline Services and Maintenance
NiGen International has the staff and expertise to help pipeline companies develop pipeline decommissioning procedures for both onshore and offshore oil and gas locations.