6.1.1 Relevant regulations from the hydrocarbon industry (oil and gas production)

Well abandonment is typically handled by national policies and procedures - therefore there is a wide range of legal directives worldwide. To provide an overview about regulations concerning well abandonment in the hydrocarbon industry the accessible regulatory data from countries significantly engaged in oil and gas production as well as international conventions were taken into account. The technical study on "Long Term Integrity of CO2 Storage - Well Abandonment" by the IEA Greenhouse Gas R&D Programme 2009 provides a lot of detailed information on abandonment regulations of the hydrocarbon industries to lead to a best practice abandonment strategy for CO2-Storage wells.

Denmark

The Danish subsoil act (L141, 2011, the Danish Parliament) serves as a basic framework for petroleum exploration and recovery. It deals in general terms of action, which leaves room for adaptations and detailed regulations. However, it regulates the exploitation and recovery activities of minerals and especially hydrocarbons in the Danish subsoil and continental shelf.

Since 2007 "A Guide to Hydrocarbon Licenses in Denmark" provides guidelines for drilling-exploration and information on well abandonment. In general the document states that exploration wells shall be plugged in such a way that no fluid flow through the hole and no communication from down-hole to surface via casing-annulus are possible. Therefore multiple plugs have to be placed. The weight of the plugs has to be sufficient to ensure that the system is in pressure balance. In uncased boreholes the plug should at least extend to 50m below and above the permeable zones, in open hole parts below the cased wells the plug should cover the interval from at least 50m above and below the casing shoe. Additionally another cement plug at 50m on top is required.

Any perforated intervals is to be isolated, cemented and plugged 50 m below and above the permeable interval. Also all plugs shall be pressure tested for a sufficient time to detect possible leakage of mechanical failure, the top cement plugs shall be located by load testing.

France

The Ministry of Economics, Industry and Employment provides the "Règlement Général des industries extractives", which was revised in the year 2000 and contains articles on closure and abandonment of wells ("fermeture définitive du puits") focusing on onshore and offshore well abandonment. The steps required are dependent on age and state of the wells, provided there is information on primary cementing and casing available. If there is no prior knowledge about the casing status, investigations are required followed by possible placing, extending and improving the cementing.

Precaution to isolate the reservoirs from each other is the primary requirement stated in the guidelines. Also the permeable layers have to remain permeable and there should not occur any mixing of fluids between different layers. Plugs with a length of at least 50m (or 100m, depending on the well bore) shall be placed according to the requirements.

Norway

In Norway any decommissioning is regulated by the 1996 "Norwegian Petroleum Activities Act" and the OSPAR Convention. In general the petroleum act requires a decommissioning plan two to five years prior to expiration of the license or termination of facility, submitted by the licensees. The decommissioning plans have to contain a disposal plan as well as an impact assessment.

The exhaustive and often referred to NORSOK Standard D-010, revised in June 2013, provides specific abandonment regulations, focusing well integrity. The primary objective is that permanently plugged wells shall be abandoned with eternal perspective. That means that NORSOK Standard D-010 requires at least one barrier between surface and potential inflow, hydrocarbon reservoirs require two well barriers. The plug lengths of 100 m should extend at least 50 m above the potential inflow-source, the plug of open hole wells shall be placed at minimum 50 m below the casing shoe. Any installations have to be verified through documentation of job performance, the position of plugs by pressure tests or tagging.

Netherlands

In 2003 a new updated mining act containing rules for exploration and development of mineral resources and mining activities was released. More technical details on well abandonment are found in the mining regulations. They state specific requirements like an additional primary cement sheath outside of the casing to well plugs and a working program to document the cementing per casing interval. Also there are extensive regulations for plug placement and uphold safety requirements, whereas little technical attention is paid on down-hole primary well cementation.

UK

The Petroleum Act entered into force in 1998. Decommissioning of onshore wells and associated hydrocarbon installations requires permission from the Department of Trade and Industry, offshore-wells need accordance with the Oil & Gas UK Guidelines for the suspension and abandonment of Wells (by UK Offshore Operations Association UKOOA). There the main characteristics of plugging material, the location of plugs for proper isolation from the surface and verification procedures for an acceptable permanent barrier are noted. In general the primary barrier characteristics required are low permeability, long-term integrity, no shrinking and non-brittle materials, which will be bonding to casing and resistant to down-hole fluids.

Two permanent barriers from surface are required to ensure an effective isolation of the hydrocarbon reservoirs. The first barrier should be placed at least 100 ft above the potential in-flow, the second barrier will serve as backup for the first one. The position and effectiveness of barriers needs to be confirmed. There are no specific requirements on the verification-process stated, but recommend minimum requirements are mentioned.

Australia

In Australia the main operations of the hydrocarbon industries are situated offshore (about 96 %), which are regulated by the Offshore Petroleum and Greenhouse Gas Storage Act 2006 as well as the Environment Protection (Sea Dumping) Act 1981. Any decommissioning is based on international protocols and treaties. There is no extensive experience on upstream petroleum decommissioning available in Australia.

Canada, Alberta

In Canada the specific policies and procedures for well abandonment are dictated by the authority of the province. In Alberta there are different abandonment programs concerning open-hole wells in oil sands for four defined areas. Generally it states that cements must be placed in a way that inhibits any cross-flow between porous zones and all non-saline groundwater has to be covered by cement. Plugs have to be extending at least 15 m above and below the isolated interval. At depths greater than 1500 m a minimum plug length of 60 m is required, for depth less than 1500 a plug of at least 30 m is considered sufficient. There is no minimum distance between plugs stated and one plug may cover several porous zones. However, the placement of plugs must be verified by an approved method.

Abandonment practices for cased-hole wells depend on the geographical location, if it was completed, and whether the well penetrated any oil sand zones. Have no oil sand zones been met, non-perforated wells do not require any additional cement plugs. Wells with oil sand intervals require separate abandonment for each completed pool and additionally all non-saline groundwater has to be covered with cement (same as in open hole). A cement plug with at least 30m length should be extending not less than 15 m below and above the liner top. Also the cement of the casing has to be in a certain required condition (Directive 009 ERCB 1990).

USA

The Regulations in USA have a distinct regional nature. However, the objective of plugging is the same in all states - primarily the protection of potable water aquifers and the isolation of hydrocarbon reservoirs. Technical details like the length of the plugs and required additives may differ from state to state. Underground Injection Control (UIC) Agency was established under the Safe Drinking Water Act (SDWA, 1974). UIC regulates at regional level the construction, operation, permitting and closure of injection wells that inject fluids in underground reservoirs. Additionally the Environmental Protection Agency (EPA) sets standards for drinking water quality. UIC defined 5 classes of wells related to the injected fluids, which require different abandonment techniques respective used material, casing condition and hydrogeological setting.

The objectives of abandonment being in general:

  • Eliminate physical hazard;
  • Prevent underground water contamination;
  • Conserve water yield and hydrostatic head;
  • Prevent intermixing of subsurface water.

The EPA regulations demand demonstration of mechanical integrity of the well before commencing abandonment. Also the mechanical integrity of the casing needs to be demonstrated before plugging. EPA states as first priority the prevention of fluid movement from the injection zone to any drinking water aquifer. Injection zone therefore require a mechanical plug with a cemented plug on top (minimum length of either 76m or 15m, depending on the used mechanical plug). Cut casing requires at least 30m cement plugging, which extends from at least 15m below to 15m above the rip point. Cement plugs must be placed at least 50m below the lowest drinking water aquifer and should ensure that no cross-flow is occurring. Any surface casing shall be cut off and the original state of the area should be restored.

API (American Petroleum Institute) provides environmentally-sound abandonment practices for oil and gas exploration, focused on onshore. API states that several safeguards, already utilized during well construction (like surface casing, production casing adequately cemented) and plugging operations (cement plugs in open holes, plugs above perforated intervals, at cut casing zones, at the base of lowermost fresh water aquifer, across surface casing shoe and at surface), help to ensure the prevention of fluid migration in abandoned wells. Cement and mechanical plugs located at critical points in the wellbore prevent fluid migration. Cement plugs should at least have a length of 30 m and extend to a minimum of 15 m above the isolating part. Perforated zones require the displacement method for plugging (cement is squeezed in or using a permanent bridge plug), with a subsequent location verification by tagging and pressure testing.

International

London Convention 1972 and 1996 Protocol is dealing with the prevention of marine pollution by dumping of wastes and other matter (in the North Sea and North-East Atlantic). The Amendment to the 1996 Protocol allows captured CO2 to be stored into sub-seabed formations (within certain restrictions). The Protocol to the convention entered into force 2006, amendment forms basis in international law to regulate CO2 storage offshore.

The OSPAR Convention is dealing with waste disposal and other activities in geological reservoirs under the seabed (in the Northeast-Atlantic). Although the OSPAR convention represents one of the most comprehensive and strict legal frameworks concerning protection of the marine environment, no specific regulation for abandonment of wells is included.