Organic Phase Mud Systems update

The Re-Assessment of the ‘Z’ Group for Organic Phase Mud Systems

As OSPAR Decision 2000/3 effectively prevents the discharge of Oil Phase Fluids (OPFs), except at <1% on cuttings, the UK authorities had previously agreed OPF mud systems could be registered on a ‘worst case’ formulation using a minimal data set.   However, it was recognised that the 'worst case' formulations were unwieldy and not representative of the way in which muds were sold or used offshore.

In addition, the Further Guidance on the Assessment of the Toxicity of Substances under the Harmonised Pre-Screening Scheme of OSPAR Recommendation 2000/4 (Reference Number 2000-4) stated that, by 01 January 2007, all offshore chemicals must be registered with full substance-by-substance toxicity data.

Therefore, DTI, Cefas and the Drilling Fluid suppliers have agreed that full ecotoxicological data at the substance level would be required by Cefas for every component in OPF mud systems so as to ensure that they are compatible with the HMCS by the required date.   Suppliers have therefore been submitting the relevant data to Cefas from 1 September 2006. 

There is no CHARM algorithm for the discharge of an OPF based mud system.  Therefore the base fluid and each individual product will be classified using the process described in the Cefas Guidelines for the classification of chemicals that cannot be ranked by the CHARM model.  Products will then be placed in the OCNS groups (A-E) appropriate to their toxicity, biodegradation and potential to bioaccumulate.  The exceptions will be those components which could also be used in a Water Based Mud (WBM) system and are CHARMable.  These components will continue to be assessed using CHARM and ranked using the HQ.  However, as the product should never be discharged when used in an OPF mud system, no RQ will be required. This process will effectively replace the old ‘Z’ Group for OPF mud systems. The ‘Z’ Group  will no longer be recognised from 01 January 2007. 

Guidance for Completing the PON15B and EEMS returns after 01 January 2007

Currently certified and approved ‘worst case’ mud systems continue to be acceptable for recording in PON15B applications up to 31 December 2006. 

• Please note, for any PON15B that has been approved prior to 31 December 2006 on a ‘worst case’ mud system, it will not be necessary to re-submit that PON after 01 January 2007 to itemise the mud components. In addition, any Variation to that PON for an increased use of the ‘worst case’ OPF mud system will not require itemised mud components.  EEMS returns for these PONs should be completed using the current system.

However, any PON15B submitted on or after 01 January 2007 MUST record the individual components of the mud system to be used offshore and each individual component MUST be fully registered with Cefas. 

The PON15: Section G1: Drilling Muds/Fluids and Chemicals

Section C1: Mud/Fluid data

The ‘mud system’ name is entered under the OPF section.  No further data need be entered as no CHARM assessment may be made. 

Please note, the ‘mud system’ name has been retained and may be found on the Cefas website but after 01 January 2007 it will no longer be recognised as a ‘registered’ product in new applications.

Section C2: Mud/Fluid formulation and chemical data

*Estimated Use - including re-cycled products

It is usual practice for ‘mud’ to be returned to shore for re-cycling and the re-cycled mud is shipped to a rig.  Additional base oil and weighting agents, emulsifiers and Fluid Loss Control (FLC) products are added as required offshore and can be identified as individual products.  The following procedures have therefore been agreed by DTI, Cefas and Industry: -

Procedure for Base Oil

PON15B Estimated Use

• It was agreed that the recycled mud could be regarded as containing predominantly base oil and a weighting agent. Suppliers analyse the recycled mud and can calculate the volume (weight) of base oil contained in that mud.
• It was agreed that the base oil in the recycled mud and the base oil to be added offshore would usually be the same product (if the base oil is not the same product the predominant base oil would be recorded). The predominant OPF name should be entered and Estimated Use would be the total of calculated recycled base oil + base oil taken offshore. (eg. Recycled base oil = 100t, added base oil =200t; total estimated use = 300t)

EEMS Returns

• It was agreed that the base oil in the returned mud could be calculated and this would be subtracted from the PON value to populate the EEMS return. (e.g. estimated use = 300t – calculated returned base oil = 150t; total use in EEMS = 150t). Through discussion it has been determined that this procedure should not cause any delays in providing returns within the stated permit conditions.

Procedure for Weighting Agents

PON15B Estimated Use

• It was agreed that a similar process could be adopted for the weighting agent and that a weight could be obtained from analysis of the recycled mud.
• It was acknowledged that the accuracy of this calculation could not be guaranteed and that other substances might affect the calculation, but it was agreed that this was a very close approximation to what was required.

EEMS Returns

• It was agreed that, as with the base oil, the tonnage of the weighting agent in the returned mud could be calculated and subtracted from the estimated use for an actual use in EEMS. Through discussion it has been determined that this procedure should not cause any delays in providing returns within the stated permit conditions.

Procedure for Emulsifiers, FLCs and Other components

PON15B Estimated Use
Other components such as emulsifiers, fluid loss additives etc would only be present in back-loaded mud in very small quantities and it would not be possible to accurately calculate them or even approximate them. 

• Therefore, it was agreed that for all other OPF products listed in the PON15B the Estimated Use tonnages would be based on what was directly supplied to the rig/installation. 

EEMS Returns

• It was agreed that ‘actual’ use of all other OPF products at the rig/installation would be recorded in EEMS.

Estimated Discharge **

The OSPAR Decision 2000/3 effectively prevents the discharge of Oil Phase Fluids (OPFs), except at <1% on cuttings.  Therefore, in most cases, the Estimated Discharge of the base oil will be ‘0’.  If discharge on cuttings occurs, a calculated Estimated Discharge tonnage should be entered and a full description of the recovered-oil-from-cuttings process should be provided in Section C: Justification.

Once all other additives have been mixed with the Base oil they too will be subject to a ‘0’ discharge. As there will be no discharge of chemicals mixed with Base oil there is no requirement for an RQ to be calculated for those products with a HQ ranking. 

Disposal Of Surplus Materials

The discharge of surplus materials is not permitted under The Offshore Chemicals Regulations 2002. Surplus materials should be retained on the rig/installation for future use OR contained and returned to shore for future use or disposal.