Oil and gas: petroleum operations notices

How to complete Petroleum Operations Notices (PONs); forms, guidance and contact details.

This guidance was withdrawn on

The Oil & Gas Authority launched a new website on 3 October 2016 to reflect its new status as a government company.

This formalises the transfer of the Secretary of State’s regulatory powers in respect of oil and gas to the OGA, and grants it new powers. This website will no longer be updated. Visitors should refer to

For PON 1 and PON 2 please refer to the BEIS website on

Applies to England, Scotland and Wales


Below you’ll find all the information you will need to understand and complete any of the PONs relevant to your needs. This includes guidance, application forms and access to the UK Oil Portal.

Petroleum Operations Notices What it is used for Quick access to application
PON 1 Reporting oil and chemical releases and Permitted Discharge Notifications from offshore installations and pipelines  
PON 2 Loss or dumping of materials at sea from offshore oil and gas installations PON 2 FAX Proforma (MS Word Document, 39.5 KB)
PON 3 Damage to submarine telecommunications cables and plant  
PON 4 Application for consent to drill exploration, appraisal, and development wells UK Oil Portal
PON 5 Application to abandon or temporarily abandon a well - handled by UK Oil Portal UK Oil Portal
PON 6 Measurement of petroleum  
PON 7 Reporting of petroleum production PPRS - submission guidance (MS Word Document, 102 KB)
PON 8 Application to complete and/or workover a well - handled by UK Oil Portal UK Oil Portal
PON 9 Record and sample requirements for seaward surveys and wells PON 9 document (PDF, 420 KB, 34 pages)
PON 9b Record and sample requirements for landward surveys and wells PON9b document (PDF, 543 KB, 13 pages)
PON 10 Reporting non-compliance with the Energy Act 2008, part 4a consent to locate. Including the failure of aids to navigation PON 10 Reporting of Non-compliance (MS Word Document, 41.5 KB)
PON 11 - reporting injuries, diseases and dangerous occurrences This notice has been withdrawn. The Health and Safety Executive has issued Offshore Safety Division Operations Notice 30 regarding the Reporting of Injuries, Diseases and Dangerous Occurrences Regulations . These apply both onshore and offshore Health and Safety Executive
PON 12 Well numbering system
PON 13 Applications for consent to drill or re-enter HP/HT exploration and appraisal wells - handled by UK Oil Portal Apply through UK Oil Portal using PON 4
PON 14a Application to carry out a Marine Survey – includes notification and/or application for a Consent (guidance notes currently under review) </a> UK Oil Portal
PON 14b Notification of intention to carry out onshore landward) geophysical surveys PON 14b application form (MS Word Document, 58.5 KB)
PON 15b Drilling Operations Application (DRA) seeking direction that an ES is not required for a proposed well, and/or associated permits, consents and licences for the drilling operations - handled by UK Oil Portal UK Oil Portal
PON 15c Pipeline Operations Application (PLA) seeking direction that an ES is not required for a proposed pipeline, and/or associated permits, consents and licences for the pipeline operations - handled by UK Oil Portal UK Oil Portal
PON 15d Production Operations Application (PRA) seeking direction that an ES is not required for a proposed development (or for the variation, renewal or extension of a production consent), and/or associated permits, consents and licences for the production operations - handled by UK Oil Portal UK Oil Portal
PON 15e Decommissioning Operations Application (DCA) seeking associated permits, consents and licences for the decommissioning operations - handled by UK Oil Portal UK Oil Portal
PON 15f Well Intervention Operations Application (WIA) seeking direction that an ES is not required for a proposed well intervention (for e.g. rig stabilisation), and/or associated permits, consents and licences for the well intervention operations - handled by UK Oil Portal UK Oil Portal
PON 16 Covering submission to accompany an Environmental Statement PON 16 application form (MS Word Document, 61.5 KB)


Damage to submarine telecommunications cables and plant

It is an offence to wilfilly, or by culpable negligence, break or injure a submarine cable in a way that might interrupt or obstruct telegraphic or telephonic communication (see Section 3 of the Submarine Telegraph Act 1885 as applied by Section 8(i) of the Continental Shelf Act 1964).

Although there are a large number of submarine telecommunications cables on the UKCS, the risk of them being damaged by offshore activity is minimal as long as operators observe reasonable caution and remain aware of their location. PON 3 aims to inform licensees of the ways in which the telecommunications industry can help them to avoid contravening this legislation.

Please note:

  • the position of out-of-service cables is likely to be approximate and the position of all cables and repeaters should be verified with the cable owners.
  • cable owners can hold any person causing damage entirely responsible for all the costs incurred in repairing damage to any cable system.
  • any person committing a punishable offence under the legislation could be punished without prejudice to civil action for damages by the cable owner.

Cable owners prefer offshore activities with the potential to damage cable systems be kept at a distance of at least one nautical mile from cables and two nautical miles from repeaters. These activities may include, but are not limited to:

  • drilling
  • core sampling and other seabed invasive techniques
  • pipeline and umbilical installation, and other construction activities
  • anchor handling operations
  • survey operations

Cable owners do recognise the preferred minimum distances are not always feasible and that the safety zone distances may not always be necessary to safeguard cable systems. Given this, please consider the following:

  • consult with cable owners before undertaking any activity that might damage cable systems. Where the precise location of the activity is not critical, it may be possible to agree with the cable owner a safe distance from the cable system from which to operate. However, if the precise location of the activity is critical and within the distances given above, you must determine the exact position of the cable system by physical inspection. The cable owner will then be able to decide on a safe minimum distance from the cable system and advise on the operational procedures and safeguards necessary to avoid damaging the cable system.
  • it may be possible to move a cable in cases where the precise location of activity will almost certainly damage the system. If the cable owner agrees to move the cable, you should expect to reimburse for all costs incurred.


Please note: In nearly all cases (including all offshore drilling), The OGA’s online consent system, WONS (Well Operations Notification System), should now be used. This is available through the UK Oil Portal. If you require portal access, please contanct the help desk on on 0300 068 5793 or at

In the few instances where the WONS system is not suitable, please follow the procedure below and use the following PON 4 application form.

Guidance for application

Certain licences comprise conditions that were issued at the time the licence was granted. Where there is a difference, the licence conditions take precedence over the guidance below and they must be adhered to. In some cases, more than 30 days advance notice of the intended time o drill may be required by other government departments – a condition that would be reflected in the licence. If full details of the proposed operation cannot be supplied with the application, the reasons for this should be explained. Failure to comply with licence conditions may result in consent being refused.

Please note the following conditions:

  • the positioning of all offshore installations for the drilling of exploration and appraisal wells, development operations and stacked rigs, requires the OGA’s approval unless the department has confirmed otherwise in writing
  • a minimum of 30 days notice is required for consent to straightforward drilling operations. Earlier notice will be necessary for operations in busy shipping areas.
  • it should be made clear in the application if an exploration or appraisal well might later be utilised for development.
  • it should not be assumed permission to occupy a site for a limited period will necessarily allow future activity on that site.

Further information about PON 4

This notice applies to all wells – exploration, appraisal and development, in both landward and seaward areas.

A consent will usually be conditional upon drilling taking place within a year of the date on which it was issued.

In the case of wells where a sidetrack is required, where no sidetrack was planned at the initial consent stage, a separate application must be made following discussion with the OGA. A faxed proforma is acceptable for this; please fax to 0300 068 5003. The proforma should also be used, with supporting information, in the case of a re-entry after suspension to drill to another target location.


Licensees must submit co-ordinates for the well location in parallels of latitude and meridians of longitude. as defined on the following datums:

  • in areas to the east of 6 degrees West longitude, the geographic co-ordinate system is defined as ED50.
  • in areas to the west of 6 degrees West longitude. the geographic co-ordinate system is defined as ETRF89.

For landward wells, locations may in addition be specified by use of grid lines of the British National Grid.

UTM co-ordinates may be supplied in addition to latitude and longitude.

The following geodetic transformations are recognised as defining the relationships between the various co-ordinate systems required for UKCS petroleum exploration and production purposes:

  • the difference between the WGS84 and ETRF89 co-ordinate systems is not significant and WGS 84 co-ordinate values can be assumed to be equivalent to ETRF89. This is equivalent to the transformation between WGS84 and ETRF89 being taken to be zero.
  • the recommended relationship between ED50 and WGS 84 or ETRF89 for petroleum exploration purposes is the “Common Offshore” transformation. The Common Offshore transformation is an operation using the position vector transformation method and a the following specified set of Helmert transformation parameters for changing co-ordinates between the WGS 84 and ED50 co-ordinate systems on the UKCS. For petroleum exploration and production purposes the transformation can also be used between the ETRF89 and ED50 co-ordinate systems.

Common Offshore transformation parameters from ETRF89 (WGS 84) to ED50

dX(m) dY(m) dZ(m) RotX” RotY” RotZ” Scale(ppm)
+89.5 +93.8 +123.1 0 0 +0.156 -1.200

Test point using Common Offshore transformation parameters

  Latitude Longitude Ellipsoid height
ETRF89 (WGS 84) 53Ý 00’ 00.000” N 01Ý 00’ 00.000” E 50.00 m
ED50 53Ý 00’ 02.887” N 01Ý 00’ 05.101” E 2.72 m

The relationship between OSGB36 and ETRF89 for petroleum exploration and production purposes be declared to be the OSGB petroleum transformation

The OSGB petroleum transformation is an operation using the position vector transformation method and the following specified set of Helmert transformation parameters for changing co-ordinates between OSGB36 (British National Grid) and ETRF89 or WGS84 co-ordinate systems. The transformation has an accuracy of typically two metres and is no worse than approximately four metres throughout Britain. A more accurate transformation is available from the Ordnance Survey.

OSGB petroleum transformation parameters from ETRF89 (WGS84) to OSGB36

dX(m) dY(m) dZ(m) RotX” RotY” RotZ” Scale(ppm)
-446.448 +125.157 -542.060 -0.150 -0.247 -0.842 +20.4894

Test point using OSGB petroleum transformation parameters

  Latitude Longitude Ellipsoid height
ETRF89 (WGS 84) 53Ý 00’ 00.000” N 01Ý 00’ 00.000” E 50.00 m
OSGB36 52Ý 59’ 58.719” N 01Ý 00’ 06.490” E 3.99 m

UKOOA landward/seaward transformation parameters from OSGB36 to ED50

The relationship between OSGB36 and ED50 for petroleum exploration and production purposes is the concatenation of the OSGB36 to ETRF89 and ETRF89 to ED50 transformations in the above recommendations, known as the UKOOA landward/seaward transformation.

dX(m) dY(m) dZ(m) RotX” RotY” RotZ” Scale(ppm)
+535.948 -31.357 +665.160 0.150 0.247 0.998 -21.689

Test point using UKOOA landward/seaward transformation parameters

  Latitude Longitude Ellipsoid height
OSGB36 52Ý 59’ 58.719” N 01Ý 00’ 06.490” E 3.99 m
ED50 53Ý 00’ 02.887” N 01Ý 00’ 05.101” E 2.72 m

Landward licences

There are additional requirements for landward licensees:

  • when an operator applies for consent to drill a well in a landward area, they must submit with that application evidence the relevant planning authority has been consulted and that planning permission has been obtained. A landward licence does not give the licensee any rights of entry onto land or over minerals and deposits other than petroleum.
  • landward wells drilled on Mining Licences (granted prior to 1966) do not require formal written consent from the OGA. However, the operator of the licence must notify the department of the location and timing of drilling operations and is required to conduct all operations according to good oilfield practice. Written consent is necessary for the abandonment of these wells (see PON 5).
  • the Mining Industry Act 1926 (section 23) requires landward licensees to give prior notification to the Natural Environment Research Council (through the British Geological Survey) of their intention to undertake drilling so the council can decide if it wishes to attend the drill site to collect samples. Please send notification to:

The Records Officer
British Geological Survey
Kingsley Dunham Centre
Nottingham NG12 5GG

Telephone: 0115 936 3109 Fax: 0115 936 3276

  1. If a licensee wishes to drill into a coal seam – whether to test for methane within the coalbed (CBM) or to test a deeper structure – they should consult the Coal Authority at an early stage in the planning process. The Coal Authority will wish to enter into an agreement with the licensee covering the conditions under which access to the coal seams will be permitted. Write to:

The Coal Authority
Bretby Business Park
Ashby Road
Staffordshire DE15 0YZ

Telephone: 01283 553 291 Fax: 01283 553 251

The following sections describe the information about the proposed well expected in an application:

Basic well data

  • should be supplied on the attached proforma
  • additional blank forms are available from the Well Consents Team
  • photocopied forms are acceptable

Prospect summary sheet

  • additional blank forms are available from the Well Consents Team
  • photocopied forms are acceptable
  • plats should be in black and white as they may be photocopied
  • one sheet should be submitted for each major reservoir target
  • the scale of the map should be shown, and the direction of North indicated if not the usual top of the form
  • at least two reference latitudes and two reference longitudes should be annotated.

Seismic depth map and representative seismic section

  • a depth map should be provided at an appropriate scale (1:10,000, 1:25,000 or 1:50,000) on top of or near to the prospective horizon[s], with the surface and planned bottom hole locations indicated, where applicable
  • one or two representative seismic sections, preferably through the well location, would be helpful

Synopsis – should briefly describe the geological rationale and objectives of drilling the well

Sampling/coring/logging and testing programme

This should include information on:

NOTE : Section 12 of the Energy Act 1976 requires a licensee to obtain the prior consent of the Secretary of State to any venting of gas. A licensee must also obtain the Secretary of State’s consent to flaring gas in accordance with the terms of his licence. A well test producing from any one interval over a period in excess of 4 days is considered to be a long term test. Testing will not usually be permitted for periods which, in aggregate, exceed 90 days. See also below, on coalbed methane wells. Include:

  • frequency of cuttings samples collection
  • objectives of the coring programme (including intervals to be cored and dependency on hydrocarbon shows) - if no coring is planned, give reasons
  • side-wall coring

NOTE : It is expected that Exploration wells will be cored in the reservoir section if there are shows. A terminal core should also be cut if age dating is uncertain. It is anticipated that all Appraisal wells will be cored in the reservoir section:

  • details of the type and scope of mud logging service to be provided
  • the formation evaluation objectives and the means proposed to achieve these

A description of the logging programme (both open and cased hole) for each casing depth plus any intermediate survey point should be included. Data on the expected formation water and mud filtrate salinities should also be provided.

Conditional logging runs should be included and the conditions noted (eg where shallow gas is expected).

NOTE: Exploration and Appraisal wells are expected to be thoroughly logged at intermediate levels as well as over target horizon[s] with:

  • an indication of the mud type and proposed weight of mud for each casing interval
  • details of proposed well testing operations - if no testing is planned, give reasons

Other relevant information

NOTE: Casing setting depths will be recorded on the Prospect Summary Sheet. However, if there is a large range of uncertainty in the possible depths, this should be indicated. Well design criteria and drilling programme details are no longer required by the OGA. Information needed:

  • details of estimated pore pressures in all permeable and porous formations, and estimated formation fracture initiation and propagation gradients at all casing shoes
  • details of the mud type and proposed weight of mud for each interval to be drilled

This information may be presented in graphical or tabular form if preferred. The offset wells used to obtain this information should be indicated. Please indicate if the proposed Exploration or Appraisal well is in an area of High Pressure and/or High Temperature, High Temperature in this context can be defined as when the undisturbed bottom hole temperature is greater than 149C (300F). High Pressure can be defined as either the maximum pore pressure of any porous formation that exceeds a hydrostatic gradient of 0,18 bar/m (0,8 psi/ft) (representing an equivalent mud weight (EMW) of 1,85 SG or (15,4 ppg) or, needing deployment of pressure control equipment with a rated working pressure in excess of 690 bar (69 MPa, 10 000 psi). Note that areas of high pressure (abnormal pressure) need not necessarily be accompanied by high temperatures and vice versa.

Shallow hazards and hydrogen sulphide

It should be clearly indicated if there is a possibility of shallow gas at the drilling site. A brief summary of the site survey could be included. For Landward wells, the following should be supplied in addition:

  • site location map(s) showing the general area and proposed drilling location, with the prospect outlined
  • a copy of the relevant page of the planning permission document

If there is a possibility of Hydrogen sulphide at any horizon in the well, this should be identified. However, note that the Health and Safety Executive (HSE) require to be informed of any incident involving H2S, Shallow Gas, or HP/HT (see PON 11).

Coalbed methane and gob gas wells

There are additional requirements for the sampling of any core cut in wells drilled for coalbed methane, the testing programme for such wells, and their completion and stimulation. Guidance will be available from :

Toni Harvey
21 Bloomsbury Street
4th Floor

Telephone: 0300 067 1611

Any enquiries regarding this Notice should be addressed to :

Well Consents Team


Measurement of petroleum

Model clauses of the schedules in the Petroleum Act 1987 and in the Petroleum (Production) Regulations 1988 require licensees to measure petroleum using methods customarily used in good oilfield practice and from time-to-time gain Minister approval of all petroleum won and saved from the licensed area.

PON 6 sets out the procedure licensees should follow to gain the OGA approval of their methods for petroleum measurement. The procedure must be followed for all new proposed methods of measurement for:

  • new field developments
  • proposed modifications to existing agreed measurement methods for fields already in production

The licensee must obtain a ‘non-objection’ from the department to use a method of measurement prior to its implementation. This is a statutory requirement.

The level of detail required by the department will vary from case to case, but the procedure for approval is the same for all field developments.

Full details of the PON6 procedure can be found in Chapter 2 of Issue 8 of the Department’s Measurement Guidelines (below)

Please contact the OGA to discuss PON 6:

Douglas Griffin
Telephone: 01224 254063


Reporting of petroleum production

PON 7 and petroleum reporting is now handled under the PPRS 2000 system. The submission guidance on this system describes the data requirements and format for the reporting of hydrocarbon production from offshore and onshore fields and terminals in the UK.

Other useful documents for PON 7 applicants


Record and sample requirements for seaward surveys and wells

PON 9 sets out the OGA’s specific requirements and licensee reporting obligations with regard seaward well and seismic data. The notice applies to all seaward surveys and all exploration, appraisal and development wells in seaward areas. It does not include notices covered elsewhere, including:

  • application for consent to drill wells
  • application to abandon or temporarily abandon a well
  • application to complete and/or workover a well
  • The OGA well numbering system (PON 12)
  • application for consent for geophysical surveys (PON 14a)
  • reporting of petroleum production (PPRS)

The specific requirements for seaward well and seismic licence data set out in this PON were agreed in principle through consultation with industry, Oil & Gas UK and PILOT in the PILOT Data Lifecycle Initiative endorsed in May 2003.

PON 9 document

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PON 9b

PON 12


This PON is for information only.

The OGA’s well registration numbering system is a simple code system that provides an unambiguous reference for use in correspondence, cross-referencing between computer databases, and in other information and filing systems.

The Petroleum Production Reporting System (PPRS) number is derived from the well number elements of the the OGA well number.

The OGA recommends that operators carefully consider their internal well-numbering systems for new projects and design them to avoid confusion with the the OGA’s well registration numbers. Please remember that the full the OGA well number must be quoted on all returns, well logs, reports and correspondence related to a well. Operators development well-numbering systems should be reviewed with the the OGA’s Licensing and Consents Unit at an early stage in development programme planning.

The terms of this notice cover both seaward and landward wells, although land wells may also have a name as a secondary identifier.

Throughout this notice the term ‘platform’ should be taken to include subsea templates and sites where development wells are clustered in close proximity, eg around a gathering manifold.

Assignment of well numbers

Once the OGA receives a drilling application from an operator, basic well details are entered into the LCU wells database. A consent letter is then issued instructing operators to inform the OGA by fax immediately (preferably within two hours) once a well spuds. At this point the OGA database automatically assigns the next sequential number. The OGA will inform the operator and the HSE of the well number within one working day of receipt of the well spud fax.

What is a well?

The OGA defines a well to be a borehole drilled into the earth from a single surface or subsurface location to a single subsurface location. If the surface location changes but target location stays the same, a new well is regarded as a respud of the first well. If the target location changes but surface location stays the same, the new well is called a geological sidetrack. If a sidetrack is made to bypass an obstruction while the surface and target locations remain the same, this is called a mechanical sidetrack. A well may be drilled intentionally into an existing well.

Shallow boreholes drilled for the purpose of rig positioning or substrate investigation (not drilled primarily for the searching, boring or getting of petroleum) will not be included in the the OGA well numbering scheme. These will not be given a Drilling Sequence Number but will be identified with the mnemonic EB (Exploratory Borehole) following the relevant quad and block number, to avoid confusion with other wells.

The OGA supports the POSC (Petroleum Open Software Corporation) international standards initiatives.

Well registration number

The OGA well number comprises seven components (a)-(g), which uniquely define a well, eg 211/30b-A21Z (this is a sidetrack of well 21 on platform A in part block 211/30b). Country Quad Block Well Number: The number is initially established when drilling commences towards a target by insertion of a number in component (f), replacing the target reference letter(s).

Definition of components of well registration number

  • Country (a): one character code to define the country in whose waters the well is drilled – UK offshore wells have a blank in this column; UK land wells have an L.
  • Quadrant (b): the number, or letter, of the quadrant in which the well is drilled. UK quadrants are areas enclosed by one degree of latitude and longitude. For quadrants with numbers, the number is up to three digits, right justified with no leading zero. Capital letters are used for quadrants with letters. The number or letter designation for the quadrant can be obtained from the map at paragraph 8.
  • Block (c): the number of the block within the quadrant in which the well is drilled. Each UK quadrant is divided into 30 blocks measuring 12 minutes of longitude by 10 minutes of latitude. The number has two digits including a leading zero.
  • Block suffix (d): used if the block is subdivided, usually after partial surrender – otherwise it is omitted. The retained part has the lower case suffix ‘a’ and the part(s) surrendered, which may be re-licensed, are given lower case suffixes ‘b’, ‘c’ etc.
  • ‘Platform’, subsea cluster designation or land site (e): for wells drilled from a fixed or floating platform, through a subsea template, or from a land grouping – one capital letter should be used for platform designation, otherwise leave blank. The letter ‘S’ should not be used to avoid confusion with subsea wells in the PPRS.
  • Well Sequence (drilling sequence number) (f): The Drilling Sequence Number (DSN) is the consecutive chronological number of the well within the block or from the ‘platform’, consisting of up to two digits with no leading zero. The chronological sequence number will be allocated to the well only after it has commenced drilling to a specific bottom hole target location, as follows:
  • exploration, appraisal or single satellite subsea development wells will normally be numbered at the time a well is spudded i.e. when drilling commences from surface
  • wells forming part of a multiwell development, in which casings are batch set prior to finalising the slot/target allocation, will be numbered only after drilling has commenced to a specific target location, normally at the time of drilling out of the 20”, or equivalent, surface casing shoe.
  • Operators are required to advise the OGA by fax immediately when drilling has commenced to a specific target location. For most exploration and appraisal wells, this fax should be sent within two hours of spudding-in to the sea bed. For most development wells, a fax should be sent within two hours of spudding out of preset casing with the intention of drilling to the target.
  • Well suffix (g)

(i) Re-spud: If a well is re-spudded for any reason, it is distinguished by an upper case character ‘A’, ‘B’, ‘C’, etc. in this component (not applicable to ‘platform’ development). A well is designated to be a respud when the original attempt to drill the well fails for any reason at or near the surface and another well must be started at a nearby surface location to drill to the same target. First respud has a capital A, second B, and so on. (ii) Sidetrack: If a well is sidetracked and the abandoned part of the hole has significant data (i.e. logs, MWD and/or core), the sidetrack is distinguished by ‘Z’, ‘Y’, ‘X’, etc. in this column. A suffix is not required if a sidetrack is for mechanical reasons only, and the abandoned part of the hole does not have significant data (i.e. logs, MWD and/or core) and is not through any known hydrocarbon bearing interval. Suffixes of re-spudded wells that are then sidetracked are replaced by ‘Z’, ‘Y’, ‘X’, etc.

Examples (4 separate wells):

1st attempt 211/03b- 21

  • respud 211/03b- 21A
  • mechanical sidetrack 1 (logged) 211/03b- 21Z
  • mechanical sidetrack 2 (cored) 211/03b- 21Y
  • geological sidetrack 211/03b- 21X

Multilateral wells will also be numbered in this way, with a suffix for each lateral. The allocation of suffixes should be agreed with the LCU Data Management Team.

Further examples of well registration numbers

  • 10/01- 2: second well drilled in block 10/01
  • 3/14a- 17: 17th well on a subdivided block
  • 2/05-H1: Heather platform well, first well drilled from platform
  • 2/05-H3Z: Heather platform well redrilled to a new bottom hole location
  • 211/28- 1A: re-spudded well
  • 15/16- 3Z: sidetracked well
  • 30/17b- 3: third well in block 30/17 in re-licensed part block 30/17b
  • 30/17a- 4: fourth well in block 30/17 in retained part block 30/17a
  • LA/07- 3: land well in quadrant A
  • L11/27- 1: land well in quadrant 11

Notes on application of system

(a) Relinquishment of part blocks - effect on well numbers

Wells within a block will continue to be numbered consecutively even after the block has been subdivided for licensing purposes, eg following partial surrender and subsequent relicensing. After subdivision however, the block subdivision suffix (eg 24/04b) must be used.

The first well drilled from a platform will take the suffix applicable to the block or part block in which the platform resides when drilling commences. All wells subsequently drilled from that platform assume the same block suffix as the first well. Once drilling has commenced on a platform, relinquishment of part of a block will not require a change in platform wells numbers, i.e. there will be no need to add a block suffix to the well registration number for existing or future wells drilled from that platform.

(b) Extension of ‘platform’ designation to subsea template, etc

All subsea structures or templates through which two or more development wells may be drilled will be given a ‘platform’ designation letter (component e) and wells will be numbered (component f) like platform wells. A platform or other installation set above the template will adopt the template designation letter. Clusters of subsea development wells will be treated in the same way as templates.

(c) Designation of wells prior to spudding-in

Wells should not be designated by drilling sequence number before spudding-in and drilling has commenced to a specific target location. Reference should be made to an identifying letter (or target location letter) for non-platform wells and for platform wells an identifying letter (following the platform letter) and slot number. A maximum of three characters can be used for the identifying letter and four for the slot number. Conductors and surface casing strings set, or planned to be set, in wells before drilling has commenced to a specific target location should be identified by the slot number following the platform or subsea cluster designation.

(d) Designation of development wells drilled out of sequence

During development drilling, batch setting of conductors may be carried out. Often reservoir targets are not allocated at this stage, in which case the wells should continue to be referred to by their slot numbers. Within two hours of the well drilling out of the conductor with the intention of proceeding to the reservoir target a fax must be sent to the the OGA. The well will then receive its unique sequential well number from the the OGA.

(e) Changes in well number after re-spudding

If after spudding-in an exploration, appraisal or single satellite development well is abandoned on mechanical grounds and the rig moved for the purpose of drilling what is effectively the same well, it can be considered in one of two ways subject to prior agreement by the the OGA:

  • add a suffix to indicate a second attempt to drill the same well (24/04- 2A).
  • call the mechanically failed attempt a well because it has reached a sufficient depth and acquired geological data which justifies so doing. In this case the second attempt is a new well and in our example would be 24/04-3 (unless 24/04-3 has already spudded elsewhere when it would be 24/04-4).

In all cases an application for consent to abandon this existing hole and drill from the new location is required.

(f) Changes in well number after re-drilling

When a well has reached its target horizon and is then drilled to a new bottom hole location, it will fall into one of the following categories:

  • the old well has production (including EWT but excluding DST) or injection history.
  • the old well has no production or injection history.

If the first above applies, the new well is termed a re-drill and re-numbered with the next consecutive chronological number. The effective date to determine the new number (spud date) will be the date the well drilled out of the existing well bore.

If the second applies, the well is considered a sidetrack and a suffix (starting from the end of the alphabet) should be added to the well number for the sidetracked well (24/04-A6Z) to aid log identification. This also applies to pilot wells and their subsequent horizontal sidetracks including multilaterals, and to a well re-entered to deepen to a new target following suspension.

In all cases an application for consent to abandon the existing section of the hole and drill to the new location is required.

(g) Well numbering – licence obligations

No aspect of (e) and (f) above implies acceptance of the wells as more than one well for licence obligation purposes.

(h) Well numbering – wells tied into platforms

Wells drilled from mobile rigs and subsequently completed and tied into a ‘platform’ (eg single subsea completions) retain their original well registration number.

(i) Reference to wells in reports and correspondence with the OGA and HSE

With the exception of references to PPRS, whenever a well, well notification, well record, report, core or sample has to be identified to the OGA or HSE, it must be referred to or labelled in the following manner:

Before allocation of the sequential well registration number (before spudding)

  • exploration, appraisal and single subsea development wells: quadrant/block - identifying letter(s) of target, eg 107/01-G
  • wells drilled from platforms or subsea clusters: quadrant/block - platform letter, identifying letter(s) (slot no), eg 23/05-H, FE (slot no 15)

After allocation of sequential well registration number

  • exploration, appraisal and single subsea development wells: well registration number, eg 107/01- 2
  • wells drilled from ‘platforms or subsea clusters’: well registration number (slot number), eg 23/05-H1 (slot no 15)

(k) Petroleum Production Reporting System (PPRS) – well number derivation from registration number

  • the PPRS number for a conventional platform or template well will be derived from elements (e) and (f) in the the OGA registration number. In the examples shown the PPRS number for well 2/05-H1 would be H01. However, unlike the Drilling Sequence Number the first nine wells from any ‘platform’ sequence should contain a leading zero.
  • in the case of single subsea completions connected to a nearby platform, the PPRS number will be derived by adding the platform letter and an ‘S’ to element (f). If well 15/16- 3Z was a single subsea completion connected to a platform whose designation letter was R then the PPRS No for that well should be RS03.
  • a possible ambiguity could arise when a subsea development well is drilled in a different block to the ‘platform’ to which it is subsequently connected. In this case the block number will be inserted after the letters and before the well number so that it is now a six-digit system, eg MS0703 and MS1203. The system depends on the full six digits being used to avoid ambiguity, hence well 3 or block 7 must be written 03 or 07 (for Magnus wells in block 211/07 and 211/12). The OGA number is prepared to consider other ways of removing the ambiguity on existing fields.

(l) Change of well number (synonymous well number)

Normally a well number cannot be changed after it has been used for identifying well records. In exceptional circumstances however, an operator may apply to have the well renumbered to fit into a ‘platform’ site sequence, e.g to make the existing well A1 if ‘A’ is chosen for the ‘platform’ site letter. Subsequent wells drilled on the ‘platform or subsea cluster’ will then be numbered A2, A3 etc. The operator must discuss potential re-numbering of wells at the earliest opportunity during development planning. Reference must be made in all communications to both the original and synonymous well number, eg 10/07- 2, A1.


PON 14b

Notification of intention to carry out onshore (landward) geophysical surveys

PON 14b should only be used by operators to notify the OGA of their intention to undertake landward surveys and/or offshore surveys and shallow drilling in internal waters.

Applicants are responsible for gaining landowner and other relevant permissions prior to carrying out any onshore geophysical survey.

Please submit the form by post, fax or email to both the OGA and UKOGL:

Toni Harvey
Oil and Gas Authority
21 Bloomsbury Street
4th Floor

Telephone: 0300 067 1611 Fax: 0300 068 5003


Neil Anderton
UK Onshore Geophysical Library
c/o Lynx Information Systems Ltd
93-99 Upper Richmond Road
London SW15 2TG

Telephone: 0208 780 2634
Fax: 0208 780 0931

PON 16

Covering submission to accompany an environmental statement

Where regulation requires submission of an Environmental Statement for a project (well, field development or pipeline), the licensee must first assess the impact it would have and provide to the Secretary of State a formal statement containing a description of the project, conclusions from the impact assessment, and proposal of any potential measures to mitigate or remedy significant adverse effects.

A number of projects in the following limited categories may not need an Environmental Statement if a preliminary assessment demonstrates to the satisfaction of the Secretary of State that the project is unlikely to cause a significant adverse environmental impact:

  • very small developments
  • drilling of wells
  • extended well tests
  • modifications to existing developments
  • small-to medium-sized pipelines

Petroleum Operations Notice 16 (application for consent) is required for all project consents covered by the regulations, regardless of their need for an Environmental Statement. For example, a PON 15 seeking direction from EIA for the drilling of a well would be ready for submission before the PON 4, so the PON 15 has to be accompanied by the application for consent, i.e. the PON 16 – not the PON 4. This application must be accompanied by an Environmental Statement (if required), and is considered a formal request for any consent required under the regulations. The PON 16 should state that its request for consent and describe the project with regard to the consent being sought. This description may reference the project’s description as stated in any accompanying Environmental Statement, i.e.the PON 16 may briefly identify the project and contain a statement that it is further described in the Environmental Statement.

The PON 16 and Environmental Statement may be submitted some weeks or even months prior to the final draft of the development programme, well consent application (PON 4) or Pipeline Works Authorisation application, provided it gives an appropriate description of the project and its assessed effects on the environment.

If the Secretary of State directs that the Environmental Statement be dispensed for a particular project, the PON 16 can still be submitted but must be accompanied by a copy of the direction.

Updates to this page

Published 22 January 2013
Last updated 11 September 2015 + show all updates
  1. Oil and Gas: Updated PON10 form document

  2. Oil and gas: PON9b - (updated)

  3. Oil and Gas: PON 9 document updated

  4. Oil and gas: PON10 Reporting non-compliance with the Energy Act 2008, part 4a consent to locate. Including the failure of aids to navigation - (updated)

  5. PON 10 - buoys removed

  6. Adding PON 10

  7. 9b Updated

  8. First published.

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