A well should be abandoned if it is no longer operational, for example if the gas production rate falls below a minimum economic level or if exploration efforts fail to discover any gas resources. Other reasons behind well abandonment may include a technical failure that prevents continued operations or changes in investor's plans.
Abandonment involves wellhead removal on the surface and filling the borehole with cement plugs. The protected well is marked with information board (the so-called “witness”). The drill site has to be reclaimed and restored to initial status.
Well abandonment is intended to prevent any impacts from the well on surface conditions and should be made so as to ensure a proper environmental protection and full isolation of penetrated aquifers and oil- or gas-bearing horizons.
The wells located in fields that are scheduled for total abandonment and those that may potentially represent environmental risks, such as blowout, fire or explosion, are the first to be abandoned. Those with a very low productivity are the last to abandon.
Drilling well abandonment is subject to applicable regulations that are secondary to the Geological and Mining Law of 9 June 2011 (2011 Journal of Laws No. 163, Item 981, as amended).
Competent authorities, including the Ministry of the Environment, Mining Offices, General Directorate for Environmental Protection, General Inspectorate of Environmental Protection, National Water Management Board, Polish Geological Institute-National Research Institute and local government authorities, are in charge of supervision over well abandonment operations.
The planned approach to well abandonment and related obligations (protection of the site, unused portion of the well, adjacent mineral deposits and reclamation of the post-mining land) should be foreseen at the stage of application for the concession (Art. 26.4 and Art. 129.1 of Geological and Mining Law dated 9 June 2011.
A Technical Well Abandonment Program should be prepared prior to the commencement of abandonment operations. The Program is prepared on the basis of an in-depth analysis of geological and engineering conditions, considering all potential constraints such as rough terrain or gas exhalation near the wells.
A documentation is prepared on completion of well abandonment for submission to the licensing authority. Ministry of the Environment is the licensing authority in the case of oil and gas exploration/production.
Well abandonment documentation is composed of descriptive and graphical sections.
The descriptive section contains information on the well drilling date, existing use of the well, dates of commencement and completion of abandonment operations and approach to the abandonment.
The graphical section contains an overview map with location of the abandoned well marked, a topographic map of the site and geological profile, including such details as well construction, borehole diameter, casing shoe depth, etc. Project information sheet conform to the standard form specified in Environment Minister's Ordinance of 15 December 2011, should be appended to the documentation.
Considering potential risks that are associated with abandonment operations (including gas exhalations), the provisions of Economy Minister's Ordinance of 28 June 2002 on health and safety at work, operations management and special firefighting measures in underground mining plants (as amended) apply to well abandonment.
Properly performed abandonment operations fall into several stages.
First, drilling rig (on-surface equipment) is disassembled and casing pipes are cut off at a depth of a few metres.
Subsequently, cement plugs are placed to fill the casing in order to isolate and protect upper and deep aquifers.
Moreover, infilling liquids (drilling mud and bentonite paste) are applied to fill the intervals between cement plugs and counterbalance hydrostatic and reservoir pressures. They also act as sealant in the event of casing failure.
Abandonment materials are selected on a case-by-case basis, depending on actual geological, reservoir and technical conditions.
Other drill site elements (auxiliary and technical facilities) are gradually disassembled and removed.
As of 17 March 2014, 23 shale gas exploration wells had been abandoned, of which 8 on a temporary basis (according to the Ministry of the Environment, Department of Geology and Geological Concessions, Hydrocarbon Division).
Permanently abandoned wells include:
- Łęgowo LE-1 (abandoned on 13.05.2013)
- KWI-Prabuty-1 ( abandoned on 15.02.2014)
- Siennica-1 ( abandoned on 12.08.2013),
- SOK Grębków-01 ( abandoned on 14.01.2014)
- Frampol-1 ( abandoned on 04.05.2012),
- Krupe-1 ( abandoned on 15.07.2013),
- ORZ Cyców-01 (abandoned on 12.01.2014)
Site reclamation intended to restore initial (pre-drilling) environmental conditions is the final stage of well abandoment.
authors: Anna Dobrzeniecka-Górka, PIG-PIB
Wojciech Labuda, Wydział Wiertnictwa, Nafty i Gazu AGH w Krakowie, Wydział Prawa i Administracji Uniwersytetu Warszawskiego, Szkoła Główna Handlowa w Warszawie