Environmental Legislation Website This Page Last Updated 30 September, 2014

Well Clean-up

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Legislation Back to Top
Key Legislation

These Regulations require a permit to be in place for all use/discharge of chemicals offshore.

The amendment regulations came into force on 30 March 2011 and clarify the status of accidental releases and the reporting procedure for PON1s.

These Regulations do not require a permit for discharge of OBM/OPF and SBMs as these are permitted under the Offshore Chemical Regulations 2002. However any contamination of well clean up fluids by reservoir hydrocarbons will require a permit if being discharged overboard (see Consents)

Consent Needed and How to Obtain It Back to Top
Consent Needed


A chemical permit is required under OCR See Drilling Chemicals and Workovers.

Oil Contamination

Under OPPC, a permit is only required if well clean up fluids are likely to be contaminated with reservoir hydrocarbons.

How to Apply


Application must be made using a Drilling Operations application (wells and sidetracks), Well Intervention Operation application or Production Operation application

Oil Contamination

Applications for a permit under the OPPC Regulations must be made via the UK Oil Portal in the new PETS system. An Oil Discharge permit must be applied for as a Subsidiary Application Template (SAT) to the asppropriate Master Application Templet (MAT).

Draft guidance notes on the new PETS system are available here.


Who to Apply to

Chemical Permit

Chemical permit applications should be submitted on the DECC UK Oil Portal

Oil Discharge Permit

Oil Discharge permit applications should be submitted on the DECC UK Oil Portal

When to Apply

PETS – submit PETS applications at least 28 days before discharge starts.

Performance Standards Back to Top
Disposal of Well Clean Up Fluids

DECC preferred option for disposal of SBM and OBM well clean up fluids is downhole reinjection (see letter from DECC). 

Backloading of Oily Slops

Operations giving rise to 'oil contaminated fluids' include well clean-up, cementing, mud pit cleaning and operations where well bore fluids become contaminated with oil based mud, crude oil or condensate. In addition, fluids from rig floor drains and other tank cleaning operations could also be included.

Backloading of slops must meet the requirements of MCA and HSE Guidance Notes:

Good Practice for the Carriage of Oil Contaminated Cargoes for Transportation by Offshore Supply Vessel (PDF).

Marine Guidance Note (MGN 283(M)) Dangerous Goods - Guidance on the Back Loading of Contaminated Bulk Liquids from Offshore Installations to Offshore Supply/Support Vessels.

HSE Safety Notice Bulletin Number OSD 3-2010

Definition of Oil

The definition of oil has been updated under the OPPC Regulations and is defined as "oil means any liquid hydrocarbon or substitute liquid hydrocarbon, including dissolved or dispersed hydrocarbons or substitute hydrocarbons that are not normally found in the liquid phase at standard temperature and pressure, whether obtained from plants or animals, or mineral deposits, or by synthesis". This definition is designed to capture all produced hydrocarbons, including condensate, and all uses of oil in the course of offshore exploration and production activities.

However, the OPPC Regulations do not apply to hydrocarbons or substitute hydrocarbons that are designated as chemicals for the purpose of the Offshore Chemicals Regulations 2002.

Reservoir Hydrocarbons

The concentration of dispersed oil in well clean up fluids discharged to sea must not exceed 30 mg/l.

The OPPC permit schedule will also specify permitted location and depth of discharge.

Minimisation of Contamination Levels

All efforts should be made to utilise technologies and operational practices in order to minimise contamination levels.

Oil & Gas UK have developed “Good Practice for Cleanup in Well Operations” and a copy of this document can be found on the Oil & Gas UK website.

Sampling/Monitoring Requirements Back to Top
Reservoir Hydrocarbon Contamination

The Oil Discharge permit schedule for well clean ups will detail the required sampling strategy (see OPPC Summary Sampling Requirements Table - Well Operations). Samples collected will be required to be analysed for dispersed oil content using current approved DECC methodology. In addition, the volume of well clean up fluids discharged must be measured or calculated to +/- 10% accuracy.

The following information must be retained offshore for a period of 2 years:

  • The date and time when each sample was collected.
  • The results of the dispersed oil concentration in well clean up fluids for each sample in mg/l.
  • The volume of well clean up fluid discharged between each sample.
  • The total volume of well clean up fluids discharged.
  • The total weight of dispersed oil in well clean up fluid discharged.
  • The average concentration of oil within the well clean up fluids discharged.

DECC Guidance on the Sampling and Analysis of Produced Water and Other Hydrocarbon Discharges is available from DECC.

Persons undertaking sampling and analysis shall be provided with sufficient information, instruction and training to undertake the task. All training records must be retained.

OBM/SBM Cleanups All chemical use/discharge must be recorded (see Drilling Chemicals).
Reporting Requirements Back to Top
What to Report - Sheens

If at anytime during the discharge a visible sheen is seen on the sea, the discharge should cease immediately and be reported to DECC through the PON1 oil spill reporting mechanisms (see Oil Pollution Emergency Planning and Reporting).

Report must be made as soon as sheen occurs. 

Reservoir Hydrocarbon Contamination

The following must be reported to DECC following completion of the well clean up operations:

  • Total volume of well clean up fluid discharged;
  • Total weight of dispersed oil in well clean up fluid discharged; and
  • The average concentration of oil within the well clean up fluids discharged.

Reports must be submitted to DECC via the Inspectorate Data Mailbox.

OBM/SBM Cleanups

One of the conditions of a chemical permit (PETS) is reporting. Reports need to cover:-

  • the name of the operator;
  • the name and location of the installation;
  • the date the permit was issued and its reference number;
  • the name and actual quantity of each chemical used; and
  • the volumes of each chemical discharged into the marine environment.

As well as being used to check actual use and discharge of chemicals against that forecast, the information gathered is used to compile the OSPAR returns, which Contracting Parties are obliged to make.

Reports need to be made electronically on the EEMS website, on a quarterly basis. Report via EEMS. For certain problematic substances, such as those identified for substitution, the Department may require more frequent reporting. A condition in the permit will make this clear if necessary.

Non Compliance Back to Top
Chemical Permits

The DECC Permit Condition non-compliance Notification Form is to be used for reporting any identified non-compliances against Chemical Permit Conditions issued under the provisions of the Offshore Chemical Regulations 2002, e.g. use/discharge of chemicals over the permitted quantities or use/discharge of chemicals not on the permit.

Change in chemical type or increase in volume of use or discharge not provided for in the permit, requires application for a variation to DECC (done through revised drilling operation permit). DECC recognises that in rare circumstances, unforeseen use of chemicals may be required at very short notice. Provision is made for oral approval for use from DECC (in consultation with MS/CEFAS) (application must still demonstrate that a consideration of environmental impact has been made) followed by a written application via the drilling operation permit for record keeping. To avoid such situations, permit application should consider contingency chemicals.

Oil Discharge Permit

Non-compliance would include discharge of well clean up fluids without a valid permit being in place or at an oil in water concentration greater than 30 mg/l.

Any non-compliance must be reported to DECC using the OPPC non-compliance notification form, which can be downloaded from the DECC website along with appropriate Guidance Notes.

Enforcement and Prohibition Notices

DECC, if of the opinion that the OPPC Regulations have been contravened, may issue an enforcement notice. This will specify the matters that constitute or are likely to constitute a contravention, steps required to rectify the matter and the time period within which these steps must be undertaken. If an enforcement notice is not addressed, DECC may take action itself and recover reasonable costs back from the operator.

If DECC is of the opinion that the operation of an offshore installation involves an imminent risk of serious pollution as a consequence of any discharge of oil, DECC may serve a prohibition notice. This will specify the pollution risk, the steps required to remove it and the time period, and may withdraw a permit wholly or in part until the prohibition notice is withdrawn.


Offences under the OPPC Regulations, include (but are not limited to) the following:

  • discharge of oil to sea without a valid and appropriate permit being in place;
  • failure to report an unpermitted discharge of oil;
  • failure to comply with a prohibition or enforcement notice;
  • failure to supply any information required under the terms of the permit; or
  • wilfully obstructing a DECC inspector.

A person found guilty of an offence will on summary conviction be liable to a fine not exceeding the statutory maximum.

DECC Inspections

The new OPPC Regulations give DECC far greater and wide ranging powers to monitor and investigate all oil discharges whether lawful or unlawful.

Inspectors may board an installation any any reasonable time and make such investigations as they consider necessary to investigate whether the requirements, restrictions or prohibitions imposed under the OPPC Regulations have been or are being complied with, or to monitor any discharge of oil.

The DECC Environmental Inspectorate Enforcement Policy sets out the general principles that Inspectors shall follow in relation to enforcement including prosecution.

Renewal and Variation Back to Top
Oil Discharge Permit If a Term Permit has been issued under the new OPPC Regulations (i.e. for an activity specific time limited discharge operation), this will only be valid for that operation and will expire after this time. A new application will be required for new planned discharge operations.
Chemicals including OBM/SBM/WBM See Drilling Chemicals
Pending Legislation Back to Top
  None at present
Snippets Back to Top
Deep Water Horizon

In addition, as part of ongoing reviews of oil spill contingency arrangements in light of the Macondo well incident, drilling operation applications for exploration, appraisal or development wells must:

  • Confirm that the operation is covered by an approved OPEP or OPEP application;
  • Include a section dealing with accidental events, summarising the worst-case scenarios assessed and modelled in the OPEP and the measures in place to prevent and control the release; and
  • Include or reference any relevant environmental impact assessment studies.
  • Additional changes may be required in the future, when DECC has reviewed outstanding reports relating to the Macondo incident.
Shipping cuttings/well clean-up fluids for offshore reinjection

Drill cuttings and the first 'flush' from well clean-ups can be shipped to another offshore site for reinjection. Supplementary advice from Derek Saward (DECC) indicates that the first flush from the well can be transported as it is deemed to still be part of the drilling process. Subsequent flushes are a new operation and could not be transported.

Note This process must be as continuous as possible - any undue delay may be deemed by DECC as a break in the process and would remove the possibility of shipment and reinjection.


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