12. SHALLOW GAS DIVERTER OPERATIONS - Is potential chemical use and discharge associated with shallow gas diverter operations subject to the Regulations?

When drilling wells at some locations, it will be normal practice to operate a shallow gas diverter that uses bursting discs to alleviate excess pressure and ensure the safety of the facility.  The diverter is only used for the well section where the shallow gas is expected, and the bursting discs are thin flexible metal and very sensitive to defects and mechanical damage.

 Prior to drilling operations, the discs are normally tested with seawater, and they may burst with discharge to the sea.  Providing the tests are undertaken using seawater and do not involve the use of any chemicals, the tests do not require to be permitted.  During the drilling operations, the discs are designed to rupture if there is excessive pressure, which could result from infrequent and unforeseen operating conditions, such as cuttings packing-off in the hole, or from shallow gas incidents.  Rupturing of the discs will result in the discharge of drilling fluids to the sea.  At the end of the relevant well section, there will also usually be a further discharge of drilling fluids, when the riser is disconnected to replace the shallow gas diverter with a BOP.  The latter is normal operating practice, as it is not possible to recycle the mud from the base of the riser, but the discharge is usually made at the sea surface rather than via the usual sub-surface cuttings disposal chute

All potential chemical use and discharge associated with shallow gas diverter operations should be included in the chemical permit application, and explained in a separate section of the Justification.  If the discharges will definitely take place (riser disconnect), this would constitute a primary chemical use and discharge.  If the discharges will only take place if there is a pressure event (bursting disc), this would constitute a contingency use and discharge.  Inclusion of the potential use and discharge in the application will avoid any PON1 or Non-conformance reporting requirements.

  1.  CLOSED UTILITY SYSTEMS - When is the use and discharge of chemicals in closed utility systems subject to the Regulations? 

 The contents of closed utility systems, such as heating, cooling and firewater systems, are not covered by the OSPAR Harmonised Mandatory Control Scheme (HMCS), and are not covered by the Offshore Chemicals Regulations 2002.  As the chemicals are not covered by the HMCS, the offshore top-up of closed utility systems does not require to be detailed as a chemical use in permit applications.  The drain-down of closed utility systems for disposal of the chemicals is not considered to be an operational discharge, and does not require to be detailed as a discharge in permit applications.   Where chemicals used in closed utility systems are not covered by a chemical permit, any chemicals drained from the systems should be returned to the shore for disposal.


 However, if there is a regular requirement to renew the contents of closed utility systems, it is recommended that the operations are included in production chemical permits.  This will simplify the approval process for any proposed offshore discharges.  However it will make it necessary to use chemicals that are on the approved lists. 

  1.  PRODUCTS POSING LITTLE OR NO RISK (PLONORs) - How are PLONOR chemicals assessed?

 Products that consist entirely of PLONOR substances, or aqueous dilutions thereof, will not have an ecotoxicological data set so they cannot be assessed using CHARM and ranked against other products.  Such products will be listed against their suppliers in the List of Notified Chemicals and identified as consisting entirely of PLONORs.

  1.  LUBRICANTS AND HYDRAULIC FLUIDS – When is the use and discharge of lubricants and hydraulic fluids subject to the Regulations?

 Section 3.3 of the Guidance Notes for the Offshore Chemicals Regulations indicates that the regulations are intended to apply to those "operational" chemicals, which are used in such a way as to result in actual or possible discharges, i.e. "operational" releases into the sea.

 The small losses of lubricants that occur during the operation of production-related equipment or machinery are not covered by the chemical permitting system, and the lubricants do not require to be notified and included in the approved chemical lists.  Thus, valve lubricants, wire-line lubricants etc, are excluded.

 Hydraulic fluids used in enclosed systems, where there is no deliberate operational discharge, are not covered by the chemical permitting system. Thus fluids used in Xmas Trees, and Blow-Out Preventers (BOP) on platform development wells are excluded. 

 Hydraulic fluids which are only discharged in an emergency are not covered by the chemical permitting system.  Thus fluids that are used in down-hole safety valves on platform development wells are also excluded. 

 Hydraulic fluids that are used in control devices that are routinely activated, resulting in a discharge to the environment, are covered by the chemical permitting system, and the chemicals must be notified and included in the approved chemical lists.  Thus, fluids used in the well control devices that are normally operated by Mobile Offshore Drilling Units (MODU) must be approved and included in chemical permit applications.

 Notwithstanding the chemical permitting requirements outlined above, it should be noted that at the meeting of the OSPAR Offshore Industry Committee (OIC) in Cadiz in February 2002, it was confirmed that the Harmonised Mandatory Control Scheme (HMCS) applied to all hydraulic fluids used to control wellheads, blow-out preventers and subsea valves.  All hydraulic fluids used in these systems must therefore be notified and included in the approved chemical lists. 

  1. TRACER AND RADIOACTIVE CHEMICALS - What is the procedure for obtaining approval for the use and discharge of tracer chemicals?

 TRACER CHEMICALS - What is the procedure for obtaining approval for the use and discharge of non-radioactive tracer chemicals?

 Chemicals that are to be used as tracers which are NOT classified as radioactive, are subject to the Offshore Chemical Regulations 2002 and must be registered with CEFAS, by providing the necessary ecotox information as required by those Regulations.  In addition, the operator must be granted a permit to use and/or discharge those chemicalsbefore they may be used/discharged offshore. 

However, in the case of operational use of tracer chemicals in “trivial” quantities it is acceptable to provide temporary approval for tracer materials that fall into this category, rather than obtaining full certification. This procedure ensures that operators have to come to the Department prior to each proposed use (to renew the temporary approval) so that the Department can ensure that the scale of use is trivial.

 RADIOACTIVE TRACERS – What is the process for gaining approval to use and/or discharge radioactive tracer chemicals?

 Chemicals that are to be used as tracers that are classified as radioactive and have a valid Registration and Authorisation Permit under the Radioactive Substances Act 1993 (RSA93), issued by either the EA or SEPA for use/discharge into the marine environment of the UKCS, do NOT require to be registered with CEFAS under the Offshore Chemical Regulations 2002.  However, the Operator will be required to ensure that a full justification of the use/discharge of the product is included in the justification section of the relevant PON15, including the name of the product to be used and the anticipated volumes to be used and/or discharged.  Any additional use/discharge must also be notified in a Variation to the relevant PON. The Operator will also be required to notify the actual volumes used and discharged to EEMS under the Radioactive Section.

  1.  MAINTENANCE CHEMICALS - What types of chemicals can be classified as being used for  maintenance?

 There are some chemicals that are considered to be for maintenance rather than operational use, and consequently there is no requirement to register these with CEFAS.  Neither is there a requirement to include them in the chemical permit or to include them in the chemical permit returns.  

Examples of these are: - chemicals used to prevent machinery or installation corrosion; products classified as coatings that are used to protect internal and external surfaces of coiled tubing from corrosion and erosion damage; products classified as “locking” compounds that are used as a material to bond casing threads or fittings 

Incidental discharges of such chemicals during treatment operations do not require to be notified to the Department.  However, the deliberate discharge of surplus or waste chemicals is not allowed, and the chemicals should be returned to shore for disposal. 

The regulations are not intended to apply to chemicals that might otherwise be used on a ship, helicopter or other offshore structure.  This effectively exempts, for example, products used solely within accommodation areas, additives to potablewater systems, paints and other coatings, fuels, lubricants, fire-fighting foams, hydraulic fluids used in cranes and other machinery etc. 

 In contrast, chemicals used for maintenance operations such as cleaning operational pipe work or vessels, are covered by the OSPAR HMCS and the Offshore Chemicals Regulations 2002.  The use and discharge of such chemicals requires to be included in chemical permit applications.

  1.  Will the regulations cover risks associated with transport to (and, in some cases, from) the platform?


No, the transport of chemicals to and from the installation would be covered by merchant shipping legislation, codes of practice etc. 

  1.  What would DECC expect to see in an ES in relation to chemical use and discharge, given that it can be prepared a year in advance of offshore operations?

 In some cases it is possible to provide detailed information in relation to chemical use and discharge, and the ES should include a full chemical risk assessment.  However, in most cases, the ES will be limited to a generic assessment of chemical use, to be supported by a formal chemical permit application submitted at a later date.

  1.  When an application is submitted, do FRS / CEFAS have sole responsibility for the evaluation of the risk assessment, or does DECC have any involvement?

The DECC Environmental Manager responsible for the operator submitting the application will coordinate the application review, and will prepare an overall assessment that takes account of the comments provided by both internal and external consultees (including the evaluation provided by FRS / CEFAS).  All internal and external consultees will be able to comment on the risk assessment, but the Environmental Manager will determine the application.

  1.  What method of analysis appropriate to determine the content of hydrocarbon discharges & substitute chemicals?

 Discharges of hydrocarbon chemicals and substitute hydrocarbon chemicals may attract a permit condition that states “Representative samples of the discharged material shall be collected at regular intervals during the course of the discharge operation(s), and analyses undertaken using a method approved by the Department to determine the hydrocarbon chemical, or substitute hydrocarbon chemical, content of the discharge(s).” 


At present, it is the responsibility of the operator to decide the most appropriate analysis methodology  However, the Department would recommend using either Gas Chromatography – Mass Spectrometry (GC-MS), Gas Chromatography – Flame Ionisation Detection (GC-FID) or Fourier Transform Infrared Spectroscopy (FT-IR), or a combination of these techniques.  If operators do not consider these techniques to be appropriate or feasible, they should contact the Department to discuss their proposals.  Further information regarding the sampling and analysis of produced water and other hydrocarbon discharges can be found at:


  1. Well bore clean-up discharge; can waste streams be put into temporary storage prior to discharge, and still qualify as an operational discharge?

 Only operational discharges can be permitted, but it is common practice to put fluids in tanks during clean-up (and other) operations, to sample and analyse the waste stream prior to discharge to ensure compliance with the permit conditions. 

 Interim storage may be necessary to check the quality of the waste stream prior to discharge, or as part of the treatment regime prior to discharge.  Providing the proposals are detailed in the permit application, it would not affect their status.  However, waste streams put into storage for “skip and ship” operations would lose their operational status, and it is unlikely that the Department would approve a subsequent application to discharge the waste at a later date, unless there were significant technical, logistical or environmental reasons for discounting the original “skip and ship” option. 

In addition to the disposal of certain surplus chemicals being covered by the OCR Regulations, (as described in 4.26 to 4.30 of the Guidance Notes), the use and/or discharge of certain trial chemicals can be regarded as an operational activity and can therefore be covered by a chemical permit. 

An example would be testing a cement unit with a trial mix prior to commencing a drilling campaign.  

Discharges of these pipe dopes are prohibited, and the Department will be refusing to accept applications that include a proposed discharge of pipe dopes containing lead.  Alternative pipe dopes that do not contain lead can be used for applications where there is an anticipated discharge, and should continue to be assessed and entered in the application and the EEMS return using the default 10% discharge estimate. 

PON15 applications to use pipe dopes containing lead should relate to activities where there is no planned or anticipated "discharge" of the dope, and should accordingly be entered in the application and the EEMS return as Zero Discharge. Text should also be included in Section C of the application to confirm the measures that will be taken to justify the zero discharge estimate (detailing how it is being used to ensure zero discharge).  


Further information in relation to the justification for continued use of pipe dopes containing lead can be found in the second attached document, which was submitted to the OSPAR Offshore Industries Committee meeting in 2010 and contains a supporting report prepared by O&GUK document (‘Industry Technical Justification to DECC:  Supporting the Continued Use & Discharge of Lead-containing Pipe Dopes beyond January 2010’).



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