Requirements
Pipelines should be decommissioned and abandoned (by removal or abandonment-in-place) in accordance with applicable national, regional and local regulations and requirements, concession terms and contractual agreements, and permit requirements. In the case of conflict the more stringent requirement should apply, unless an exception procedure is implemented to approve and document the deviation. Pipelines should be abandoned using generally accepted engineering and construction practices, proven industry processes, methods and procedures, as well as with due consideration for health, the environment and safety, sustainability and reuse, and Company reputation, both during abandonment activities and considering future land or sea use.
- All onshore pipelines on the surface, and in depths shallower than 200 feet (below mean sea level) should be removed, unless buried to an acceptable depth below the surface or seabed suitable for abandonment-in-place. If abandoned in place, pipeline stability should be assured over the long term.
- If a pipeline (or group of similar pipelines) is a candidate to be abandoned-in-place, a risk assessment should be performed in the early phase of abandonment planning to determine whether the pipeline should be removed or abandoned-in-place. The risk assessment should be consistent with the HSE risk management process and evaluate HSE, business, social, and reputational risk. The risk assessment should evaluate relevant criteria (such as potential public exposure, future land or sea uses, e.g. fishing or shipping, regulatory requirements, rights-of-way, landowner agreements, and technical feasibility) and the results documented and considered in making the removal versus abandonment-in-place decision. If abandonment-in-place is selected, appropriate mitigations should be implemented based on the risk assessment results.
- A pipeline should not be removed or abandoned in place without first being cleaned to an acceptable standard, which is normally achieved by pigging and then flushing or purging the pipeline of hazardous liquids and gases, including hydrocarbons or other materials. Materials flushed or purged from liquid pipelines must be captured and sent for proper reuse or disposal. Gaseous materials may be permitted to be vented to atmosphere or to a control device if not purged to an active pipeline segment or otherwise captured for reuse. Regulatory approvals and permits may be required for the venting of gaseous materials or routing to a control device. The HSE department should be consulted for guidance on acceptable criteria and requirements for disposal or discharge of liquids and gases.
- An unidentified pipeline should not be cut, sheared, drilled or welded upon. If unsure, check all related documentation (e.g. drawings, surveys, maps, regulatory records), interview operations staff (current and previous) and discuss with other operators that have pipelines in the vicinity to positively identify the pipeline in question. If questions persist, perform additional surveys and trace the line to its source (e.g. with sonar or divers) to positively identify the pipeline.
- Hazardous wastes should be properly disposed of at an approved hazardous waste facility. Decommissioned materials containing hazardous wastes should either be sent to a decontamination facility (where the hazardous wastes should be removed and properly disposed of at an approved hazardous waste facility) or disposed of at an approved hazardous waste facility.
- Environmental site assessment, remediation, and restoration should be coordinated with the pipeline abandonment work. Environmental Subject Matter Experts should be engaged during project planning and execution phases to determine if environmental assessment, remediation, and/or restoration activities are required. Onshore, coastal and offshore areas (land or seabed surfaces) should be left in a state suitable for subsequent use, without being a hazard to users of the areas.
- Pipeline abandonment projects should define minimum technical capability and experience expectations within contract plans and bid/tender packages as needed to assure workforce competency for work execution.
- Items to consider in early-phase project framing and alternative development include pipeline abandonment-in-place versus removal, timing of work activities, regulatory requirements, HSE issues and risks, financial issues and risks, disposal requirements, and stakeholder requirements or expectations. Each region where Company operates may have unique requirements, and the abandonment plan must be suited to the overall goals of both Company and external stakeholders.
- Site visits and inspections should be undertaken during the planning and engineering phases to build an understanding of the site and establish detailed site-specific information, to identify issues that may need to be addressed in site-specific abandonment procedures or incorporated into analytical models, and to develop detailed abandonment execution plans and removal procedures.
- The site visit and inspection should include assessment of the condition of the pipeline, associated facilities and infrastructure, and site conditions. The visit should include inspection, testing and documentation of the presence of hazardous materials. Typical materials that might be encountered at pipelines and associated facilities (which may or may not be hazardous) include the following:
- Naturally occurring radioactive material (NORM)
- Asbestos
- H2S
- Mercury
- Paint and lead-based paint
- Batteries
- Hydrocarbons
- Polychlorinated biphenyls (PCBs)
- Chemicals of unknown composition
- Containers of unknown material
- A basis of estimate document should be developed for each pipeline abandonment project to guide the development of cost estimates. Where possible, individual pipeline abandonment projects may be grouped to form a campaign and thereby provide more leverage in dealing with contractors for securing equipment and reducing costs, and in gaining efficiencies through process repetition.
- The following items should be considered and incorporated as appropriate during early phase project development and planning.
- Regulatory requirements governing pipeline abandonment vary by country, and even within various regulatory jurisdictions within a country. Therefore national, regional and local regulations, concession terms and contractual agreements, and permit requirements should be reviewed, as well as government decrees in place at the time of project development and planning, including those that define hazardous wastes and hazardous waste management requirements. Permits are generally required where a regulatory framework exists, and some permitting processes may require a public comment period.
- A Transportation and Waste Management Plan should be developed that covers the handling, storage, transport and disposal of all wastes, including the recycling of scrap materials and the disposal of wastes, both hazardous and nonhazardous materials.
- Pipeline abandonment risks should be assessed using the HSE Risk Management process to evaluate HSE, business, social, and reputational risk. Risk registers that include HSE, project execution and Company reputational risk factors should be developed and appropriate risk mitigation plans developed and managed. Assets with similar HSE, reputational, and project execution risks may be grouped together to facilitate assessment.
Onshore Pipeline Abandonment
All onshore pipelines should be removed unless buried to a minimum of 3 feet below the surface, in which case abandonment-in-place may be an alternative. Where national, regional or local regulations and requirements, concession terms and contractual agreements, or permit requirements allow abandonment-in-place at depths shallower than 3 feet, a risk assessment should be performed to confirm that abandonment-in-place is sufficiently protective of the Company’s interests from all perspectives, including HSE, business, social, and reputation. If the risk assessment confirms that abandonment-in-place is sufficiently protective of the Company’s interests then an exception procedure is not required. For onshore facilities, minor equipment, piping and appurtenances (and subsurface infrastructure) associated solely with pipeline operation and safety may be decommissioned and removed with the pipeline.
- Plan the pipeline abandonment, including isolation, draining, pigging, flushing, contents disposal, removal versus abandonment-in-place, and reclamation and restoration of impacted areas. Perform site visits, surveys, content-sampling, survey-map reviews, etc., as needed, as well as identifying in-line valves, repair locations, pipeline crossings, dead legs or other features that may require mitigation procedures.
- Pipeline right-of-way agreements should be reviewed for special requirements, and to verify that the agreement will not be violated or that Company rights will not be unintentionally relinquished.
- Sample the pipeline to determine the contents, then check contents for hazardous chemicals, materials or wastes (e.g., NORM, mercury or benzene) and check external coatings such as paint and insulation for potentially hazardous wastes (e.g., lead, asbestos, PCBs) that might require special handling procedures, disposal permits, or both.
- De-energize and isolate the pipeline from energy sources. Where a pipeline to be abandoned is connected to other pipelines (or segments) that are to remain active (live), inactive or idle, the abandoned pipeline should be isolated by physical removal, e.g., “air-gapped.” All abandoned connections to active, inactive or idle pipelines should be permanently closed with flanges and blinds (or weld caps) per the pipeline material classification or specification. All welds and flanged joints installed to achieve isolation should be inspected and tested per the pipeline material classification or specification. Lock out and tag out all sources of energy (e.g., pumps, rectifiers, cathodic protection systems, and valves) that are not physically disconnected.
- Drain pipeline and dispose of the contents per the Company’s waste management plan. For pipelines with unknown or uncertain integrity, perform a negative pressure test (normally 10–15 psi for 12 hours) to verify pipeline integrity for subsequent pigging and flushing operations.
- Pipelines with suitable integrity (or with a successful negative pressure test) should be pigged and flushed to remove as much of the remaining contents as possible. For pipelines with uncertain integrity, consider using negative pressure to pull a pig thru the pipeline to remove fluids, which mitigates the risk of releasing contents to the environment. Recover all fluids and dispose of as per the waste management plan.
- Flush or purge the pipeline to the cleanliness level specified by national, regional and local regulations and requirements, concession terms and contractual agreements, or permit requirements. If unspecified by regulations or contractual agreement, project team should set the minimum cleanliness level, which for example may be specified in parts per million or “flushing until clear returns”, e.g., until there is no sheen on receiving waters in a static sheen test. The minimum cleanliness requirement should be flushing until clear returns if no other requirements have been established. The minimum pipeline flushing volume to achieve clear returns should be 150% of the pipeline volume, but flushing efficiency is also dependent upon achieving adequate flow velocity, so higher volumes/flowrates may be required.
- Drain the pipeline to remove, recover and dispose of flushing fluids per the waste management plan. Re-pigging the pipeline with an inert gas (typically nitrogen) is one method to remove flushing fluids.
- Prior to severing or cutting a pipeline, verify the pipeline is depressurized and free of hazardous liquids and gases, including hydrocarbons.
- Pipelines (or segments) that are abandoned in place should meet the following requirements:
- Each end of the pipeline should remain buried to a minimum depth of 3 feet or greater. Measures should be taken to ensure the pipeline ends remain stable and do not experience excessive settlement or buoyant movements during seasonal changes in soil conditions.
- Each end of the pipeline should be sealed with a welded cap, a steel plate, a skillet plate, a blind flange, a locking plug, or a grout plug.
- Each end of the pipeline should be permanently identified and then covered with appropriate materials.
- Grouting of pipelines should be required where loss of integrity (e.g. collapse of the pipe, holes, buoyancy) could potentially result in an unacceptable risk or liability to the Company (e.g. pipe greater than 10 inches in diameter under roads or railroads, under canals, dikes, sea defense or dune crossings where the water level is higher than the surrounding land surface, or where local regulations require continuous plugging). Grouting should form a continuous plug throughout the pipeline (or section of pipeline) to mitigate the risk to an acceptable level.
- Pipelines should be marked with above-ground pipeline warning markers if required by applicable national, regional or local regulations and requirements, concession terms and contractual agreements, or rights-of-way or permit requirements.
- Pipelines (or segments) that are removed should meet the following requirements:
- Pipelines on the surface should be removed by severing in place and removal.
- Pipelines buried shallower than 3 feet in depth should require excavation, severing and removal. Excavation should follow established safety procedures and may require special permits.
- Cold-cutting methods are preferred (e.g., shearing, reciprocating or circular metal saws) over hot work methods from a safety perspective. All work should follow applicable safety procedures.
- Remove all associated pipeline surface and subsurface infrastructure (including at coastal sites) unless they have future economic utility.
- Remove all pipeline minor equipment, piping and appurtenances associated solely with pipeline operation and safety, unless they have future economic utility.
- Associated pipeline infrastructure such as buildings, roads, power lines, gravel pads, and concrete pads should be removed unless regulations, government requirements, concession or landowner/lease agreements stipulate that they remain in place.
- Document final site condition and retain all records (including, for example, “as abandoned” drawings, before-and-after photos or videos, regulatory submittals, permits and approvals, contractual records, route maps and end points of abandoned-in-place pipelines, sampling reports, and inventory data).
Offshore Pipeline Abandonment
All offshore pipelines in water depths shallower than 200 feet below mean sea level should be removed, unless buried to a minimum of 3 feet below the seabed surface, e.g. below the natural seafloor, in which case abandonment-in-place may be an alternative.
Reburial to the 3 feet minimum below the seabed surface may also be an acceptable alternative to removal. Buried pipelines in water depths from 200 feet to 300 feet are candidates for abandonment-in-place regardless of burial depth, provided that they do not present a hazard (obstruction) to navigation, commercial fishing (trawling) activities or future use. Where national, regional or local regulations and requirements, concession terms and contractual agreements, or permit requirements allow abandonment-in-place at depths shallower than 3 feet a risk assessment should be performed to confirm that abandonment-in-place is sufficiently protective of the Company’s interests from all perspectives, including HSE, business, social, and reputation. If the risk assessment confirms that abandonment-in-place is sufficiently protective of the Company’s then an exception procedure is not required.
- Plan the pipeline abandonment, including isolation, contents disposal, removal versus abandonment-in-place, and impacted areas. Perform site visits, surveys, contents sampling, survey map reviews, etc., as needed, as well as identifying in-line valves, repair locations, anchors, anchor mats, pipeline crossings, power or communications cable crossings, dead legs or other features that may require mitigation procedures. During the site visit, meet with field engineers and operators to discuss the history and condition of the pipeline (e.g., last time pigged, paraffin plugs, corrosion issues, repair details, and number of repairs) and identify potential concerns such as areas of high scour, sea bottom mudslides, and environmentally sensitive areas.
- Pipeline agreements (e.g. right-of-way, crossing, access to third party facilities, fluid handling) should be reviewed for special requirements, and to verify that the agreement will not be violated or that Company rights will not be unintentionally relinquished. Particular attention should be given to retaining rights-of-way at shore crossings where future use is of concern.
- Where seabed or environmental conditions (e.g., mud flows, erosion, currents, storms, mudslides, sediment movement, seismic events) may have caused a pipeline to move or shift, consider surveying affected pipelines with sonar equipment or by diver with a GPS pinger. The intent is to verify the line location, identify damage and locate impediments to abandonment (e.g., pipeline crossings, electrical power or communications cable crossings, valves, repair clamps, auger anchors, and concrete mats), and to determine the type and location of debris (shipwrecks, containers, etc.) on or near the pipeline. This information will be critical for planning pipeline abandonment.
- Sample the pipeline to determine the contents, then check contents for hazardous chemicals, materials or wastes (e.g., NORM, mercury or benzene) and check external coatings such as paint and insulation for potentially hazardous wastes (e.g., lead, asbestos, PCBs) that might require special handling procedures, disposal permits, or both.
- De-energize and isolate the pipeline from energy sources. Where a pipeline to be abandoned is connected to other pipelines (or segments) that are to remain active (live), inactive or idle, the abandoned pipeline should be isolated by physical removal, e.g. “water gapped” or “air gapped”. All abandoned connections to active, inactive or idle pipelines should be permanently closed with flanges and blinds (or weld caps) per the pipeline material classification or specification. All welds and flanged joints installed to achieve isolation should be inspected and tested per the pipeline material classification or specification. Lock out and tag-out all sources of energy (such as pumps, rectifiers, cathodic protection systems, and valves) that are not physically disconnected.
- If possible, pig the pipeline to be abandoned. Recover all fluids and dispose of them in accordance with the waste management plan, taking into account waste characteristics.
- Flush or purge the pipeline to the cleanliness level specified by national, regional and local regulations and requirements, concession terms and contractual agreements, and permit requirements. If unspecified by regulations or contractual agreement, the project team and management should set the minimum cleanliness level, which for example may be specified in parts per million or “flushing until clear returns”, e.g., until there is no sheen on receiving waters in a static sheen test. The minimum cleanliness requirement should be flushing until clear returns if no other requirements have been established. The minimum pipeline flushing volume to achieve clear returns should be 150% of the pipeline volume, but flushing efficiency is also dependent upon achieving adequate flow velocity, so higher volumes/flowrates may be required.
- Pipelines should not be cut, severed, sheared, drilled or welded upon unless it can be positively identified along its entire length (with no risk of misidentification) and there is a reasonable assurance that it has been flushed, depressurized to an equilibrium state, and is free of hazardous liquids and gases, including hydrocarbons. Suitable safeguards should be employed to mitigate risk (i.e., drilling a pilot hole and checking contents, setting a pollution dome, etc.) and to protect against releasing hazardous materials to the environment.
- Where there is any doubt or question relative to the identity, depressurization or cleanliness of a pipeline, and the decision has been made to proceed with cutting, severing, shearing, drilling or welding, suitable precautions should be taken to mitigate the higher risk. One proven industry practice is to use “hot tap” methods to verify that the pipeline is depressurized, and to confirm that the pipeline has been flushed and cleaned, and the contents are suitable for release to the environment. The “hot tap” provides a means of controlling flow and sampling/testing the contents, and if the contents are not clean it provides a means of localized flushing to further clean the line. The “hot tap” provides pressure and flow control mitigation against cutting into the wrong pipeline, which could be pressurized with hazardous contents.
- Whether severed in place for removal or abandonment-in-place, precautions should be instituted to protect divers, surface personnel, equipment and marine vessels, and the environment during subsea work. Containment domes (hoods) are one mitigation method against inadvertent fluid releases during subsea severing of pipelines.
- On conventional fixed structures the pipeline and tube turn are often severed and removed together, and the riser left in place for removal with the jacket as part of facility decommissioning. In this case the pipeline riser should be severed inside the jacket footprint, and sufficiently supported by the jacket to allow safe lifting with the jacket. A plug should not be placed in the bottom of a riser as it can present a projectile hazard during jacket lifting and removal.
- Abandoned pipeline segments, and related appurtenances such as risers, equipment, and piping that are cleaned and abandoned, but not removed should be identified as such with nameplate tags. The tags should include the pipeline number (or segment number), with date abandoned, and facility “to/from” information. Nameplate tags are typically fabricated from brass (other materials may be acceptable) and should be attached with nylon tie-wraps if subsea, and with stainless steel wire if on surface facilities.
- Pipelines (or segments) that are abandoned in place in water depths of 300 feet or less should meet the following requirements unless noted otherwise:
- Each end of the pipeline should be buried to a depth of 3 feet or greater. In areas with evidence of seabed scour, additional precautions should be taken to mitigate erosion resulting from abandonment activities.
- Each end of the pipeline should be sealed with a blind flange or a locking plug regardless of water depth, i.e., even in water depths greater than 300 feet. Examples of suitable locking plugs include a “dogging type internal plug” on pipelines 6 inches and larger and a “dogging external sealing cap” on pipelines 4 inches and smaller. A rubber plumber’s plug is not an acceptable long-term locking plug.
- Each end of the pipeline should be stabilized at the burial movement. Stabilization should be accomplished with an engineered solution based on seabed conditions and likely loads, or by utilizing proven industry practices. In shallow water, hurricane (typhoon) prone areas (such as the United States – Gulf of Mexico) a proven practice utilizes an auger-type anchor and steel cable to temporarily secure the pipeline end, followed by permanent stabilization with cement bag coverage.
- Where an auger-type anchor is used to temporarily stabilize the end of a pipeline, it should be fully embedded and externally attached or looped to the pipeline end with a 1/2-inch cable. Cement bags (not simple sand bags) should be placed over the end of each pipeline to extend 6 feet in front of, 3 feet behind and 3 feet to each side past the end of pipe as a minimum. If allowed by regulations, requirements and agreements, concrete mats may be used in lieu of cement bags to cover the ends of the pipeline.
- The resulting surface should be even with natural seabed surface and should not present an obstruction to navigation or commercial fishing (trawling) activities, e.g., the top of cement bags, concrete mats, etc. should not protrude above the natural seabed surface.
- Pipelines (or segments) that are removed should meet the following requirements:
- Pipelines on the seabed surface may be severed in place, and then lifted or pulled to the surface, and transported to shore facilities for clean-up and disposal or salvage (material recycling).
- Pipelines buried below the seabed surface should require excavation, severing and removal. Some seabed soil conditions may allow pulling of the pipeline out of the seabed to the surface without excavation, but caution must be used as obstructions (such as other pipelines or cables) may be hidden and could pose significant risks.
- Pipelines are typically severed on both sides of crossings (other pipelines or cables) to eliminate the risk of damage at crossings during pipeline lifting or pulling to the surface, and then the pipeline segment under the crossing carefully removed.
- If reverse-lay operations are employed, the subsea end of the pipeline segment should be sealed with a locking plug or cap to contain the contents during pulling to the surface. Plugs or caps should be mechanically attached and able to withstand the forces encountered without releasing. Examples of suitable locking devices include a “dogging type plug” on pipelines 6 inches and larger and a “dogging cap” on pipelines 4 inches and smaller. A rubber plumber’s plug is not an acceptable locking plug.
- Associated pipeline subsea infrastructure and appurtenances (such as pipeline manifolds, jumpers, pipeline end manifolds [PLEMs] and terminations [PLETs], anchors, pilings, concrete mats, riprap, cement bags, etc.) should be removed as required by national, regional and local regulations and requirements, concession terms and contractual agreements, and permit requirements, and as follows:
- Subsea infrastructure and associated appurtenances in water depths of 200 feet and less should be removed, unless flush with or buried below the seabed surface.
- Subsea infrastructure and associated appurtenances in water depths from 200 feet to 300 feet should be removed, unless flush with or buried below the seabed surface, unless they can be demonstrated through a risk assessment to not present a hazard (obstruction) to navigation, commercial fishing (trawling) activities or future use.
- Subsea infrastructure and associated appurtenances in water depths greater than 300 feet do not have to be removed solely due to surface hazard (obstruction) considerations.
- Remove all concrete foundations, footings, and other subsurface infrastructure (such as drains and sumps) in coastal sites (onshore) that are included in offshore pipeline abandonment.
- Remove all pipeline surface minor equipment, piping and appurtenances associated solely with pipeline operation and safety, unless they will be removed during facility decommissioning or have future economic utility.
- Document final site condition and retain all records (including, for example, “as abandoned” drawings, before-and-after photos, videos or sonar scans, regulatory submittals, permits and approvals, contractual records, route maps and end points of abandoned-in-place pipelines, sampling reports, and inventory data).