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Allocation of Unidentified Gas Statement. 16th May 2011. Outline. Introductions Presentation of the AUGS High level plan Consultations/presenting to industry Allocation of Unidentified Gas Understanding of the problem Proposed methodology Summary / Q&A Future Meetings AOB.

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Presentation Transcript
  • Introductions
  • Presentation of the AUGS
    • High level plan
    • Consultations/presenting to industry
    • Allocation of Unidentified Gas
      • Understanding of the problem
      • Proposed methodology
    • Summary / Q&A
  • Future Meetings
  • AOB
what is gl
What is GL?
  • GL is a world class technical
  • assurance and consulting company and
  • leading ship classification society.
  • Three business areas:
  • Maritime Services
  • Renewables – GL Garrad Hassan
  • Oil And Gas – GL Noble Denton
gl noble denton our heritage
GL Noble Denton - Our Heritage

Originally formed as the Research and Development Group of British Gas

With the re-structuring of British Gas our name changed to BG Technology and acquired Transco Engineering Services & Transco Technical Training in 1997

In 2001 we acquired Risx and Stoner Associates Inc. and became Advantica

In 2007 Advantica was acquired by Germanischer Lloyd


GL Noble Denton has become a leading global advisor to the Oil & Gas industry

Oil & Gas assets

3,000 Employees in35 Countries







Subsea Installations


Offshore Structures

Onshore Facilities
























Saudi Arabia








Competencies along the whole asset life cycle

GL Noble Denton comprises experts from:

Technical Assurance

  • Verification, Certification and Classification
  • Industrial Inspection

Marine Consulting & Operations

  • Marine Warranty
  • Marine Consulting, Vetting & Surveys, Marine Operations
  • Marine Casualty Investigation
  • Dynamic Positioning

Advanced Engineering & Consulting

  • Adv. Analysis & Eng. Consulting
  • Field Development Planning
  • Testing Services
  • Asset Integrity Mgmt / Optimization
  • Safety & Risk
  • Software Solutions

Project Execution

  • Project Management
  • Design
  • Transportation & Installation
  • Due Diligence
  • Construction Monitoring
conflicts of interest
Conflicts of Interest
  • GL Noble Denton is independent of all UK industry bodies
  • GL Noble Denton have not previously been involved with this particular unidentified gas problem
  • One of our core values is to be “the most respected international technical advisor and trusted partner” for all our clients
  • Our objectives are simple – to devise a methodology that is unbiased, meets the requirements of the industry bodies and is approved by the UNCC
presenting to the uncc
Presenting to the UNCC

The AUGS covers

  • Adherence to AUGE Guidelines terms of reference
  • Proposed topics for unidentified gas and their status
  • Data provision status/issues
  • AUGE Methodology
    • Reasoning
    • Assumptions
    • Data Used
    • Issues/recommendations going forward
    • For incomplete aspects of the methodology (e.g. pending data) the AUGS contains details of the remaining steps to complete it
  • Consultation questions and responses as appropriate
reporting progress
Reporting Progress
  • Primarily through the main UNCC presentations and publications of AUGS
  • There is also visibility of activities from data requests and responses to consultation questions
  • In addition, brief progress reports will be provided via JO website

Industry Bodies


  • GL Noble Denton
  • present answers via
  • AUGS
  • Industry meetings
  • JO website

GL Noble Denton

Industry Bodies


  • Collate
  • Compare vs criteria
  • Investigate / assess
  • Generate responses
  • Update methodology
  • Update AUGS

Questions/issues can be raised via

unidentified gas understanding of the problem
Unidentified Gas – Understanding of the Problem
  • The AUGE
    • Robust and repeatable algorithm
    • Estimates of Unidentified Gas that are
      • Accurate
      • Unbiased
    • Unidentified Gas estimation is the core of the consultation/publication process
unidentified gas statement of the problem
Unidentified Gas – Statement of the Problem
  • UK gas market sectors
    • Daily Metered (DM)
    • Non-Daily Metered Larger Supply Points (NDM LSP)
    • Smaller Supply Points (SSP)
    • Threshold between SSP and LSP is 73,200kWh pa
unidentified gas statement of the problem1
Unidentified Gas – Statement of the Problem
  • Additional factors:
    • LDZ Shrinkage
      • Leakage
      • Own Use Gas
      • Transporter-Responsible Theft
    • Unidentified Gas
    • Both unknown, both have to be estimated
unidentified gas statement of the problem2
Unidentified Gas – Statement of the Problem
  • Unidentified Gas
    • Unregistered and Shipperless sites
    • Independent Gas Transporter CSEP Setup and Registration Delays
    • Corrections to the shrinkage estimate
    • Shipper-responsible theft
    • Potential additional sources of Unidentified Gas
      • LDZ offtake meter errors
      • Supply point meter errors
      • These only apply if there is a long-term metering bias
unidentified gas statement of the problem3
Unidentified Gas – Statement of the Problem
  • Calculation of Unidentified Gas
    • Understand process flow
      • Location of UG at each stage of the calculation
    • Calculate UG at optimal process stage
      • Directly
      • By subtraction
    • Time frame covered by individual UG calculations
      • Daily (aggregate results to annual level for UNC table)
      • Monthly (aggregate results to annual level for UNC table)
      • Annual
unidentified gas statement of the problem4
Unidentified Gas – Statement of the Problem
  • Previous UNC Modification Proposals
    • 194/194A
      • Gave framework for quantifying Unidentified Gas
      • Relied on set percentages of RbD or set values
    • 228/228A
      • Populated framework with set percentages (228) or set values (228A)
      • No provision for year-on-year updates at this stage
    • Potential areas for improvement
      • Both carry assumption that all or most of RbD is Unidentified Gas
      • Recognition of allocation algorithm error
unidentified gas statement of the problem5
Unidentified Gas – Statement of the Problem
  • The AUGE is independent and impartial
  • Modification 229 allows UG estimates to be updated every year
    • No UNC amendments required
  • Estimates from the AUGE circulated and agreed prior to implementation
unidentified gas the solution1
Unidentified Gas – The Solution

Daily Allocation Process

  • Based on End User Categories
  • Trained on metered data
    • Minimum 3900 Small NDM, 1600 Large NDM supply points
    • 2010 analysis actually used a total of 12715 supply points
  • Estimates raw (metered demand) – i.e. no Unidentified Gas
  • Scaled up to meet LDZ load (minus Shrinkage and DM load)
  • Scaling process introduces Unidentified Gas
    • Value unknown
    • Split between EUCs by AQ
unidentified gas the solution2
Unidentified Gas – The Solution

Composition of allocation estimate

  • Actual EUC load
  • Model error (can be positive or negative)
  • Unidentified Gas (always positive)
  • Each EUC total known, but composition unknown
unidentified gas the solution3
Unidentified Gas – The Solution

Final calculation steps

  • Aggregate to SSP and NDM LSP level
    • SSP corresponds to one EUC
    • NDM LSP is the sum of the remaining EUCs
    • This is the basis for initial (deemed) load allocation
  • Actual NDM LSP (monthly) meter reads become available
  • Apply Reconciliation by Difference
    • NDM LSP load now accurate
    • Model error eliminated
    • SSP allocation is now actual SSP load plus Unidentified Gas
    • SSP/UG split unknown
unidentified gas the solution5
Unidentified Gas – The Solution

Unidentified Gas Estimation

  • Location known, UG accumulated into one figure
  • Estimate should now be made
  • Recommended approach – calculate each component directly
  • Calculation granularity is part of analysis
unidentified gas data requirements
Unidentified Gas – Data Requirements
    • Site AQs (for all DM, LSP and SSP sites)
    • Actual daily loads (DM sites)
    • Profiled daily loads (from meter reads for LSP NDM sites)
    • Deemed daily loads (LSP NDM and SSP sites)
    • RbD quantities
    • LDZ Shrinkage (calculated)
  • Plus data for
      • Unregistered and shipperless sites
      • IGT CSEP setup and registration delays
      • LDZ shrinkage initial and final estimates
      • Theft (including information on anti-theft initiatives)
unidentified gas unregistered shipperless sites
Unidentified Gas – Unregistered/Shipperless Sites
  • Unregistered Sites
    • Opening meter reading taken when site is registered
    • If this is not zero, Unregistered gas has been taken
  • Shipperless Sites
    • Closing meter reading taken when site is unregistered
    • Opening meter reading taken when site is registered
    • If they differ, Shipperless gas has been taken
    • This gets assigned to SSP sector via RbD
  • Potential impact of Mod 369
unidentified gas unregistered shipperless sites1
Unidentified Gas – Unregistered/Shipperless Sites
  • Unregistered Sites – Shipper Activity/Orphaned
    • Data has been requested splitting these into “meter”/”no meter” categories
    • Determine proportion with meter that actually flow gas before they are registered
    • Analyse all opening meter readings to derive percentage non-zero
    • Apply this proportion to “meter” group
    • All sites in this group are more than 12 months old, hence unregistered consumption = AQ
  • Unregistered Sites – Sites Created <12 Months
    • Proportion flowing gas the same as for Shipper Activity/Orphaned sites
    • Assume that rates of new sites getting MPRNs and sites with MPRNs becoming registered are both steady
    • Sites will, on average, have been taking gas for half the time period in question
    • Report currently semi-monthly, hence average time taking gas is one month
unidentified gas unregistered shipperless sites2
Unidentified Gas – Unregistered/Shipperless Sites
  • Shipperless Sites – Passed To Shipper
    • Only sites visited after being shipperless for more than 12 months are reported
    • More sites will have been shipperless for less than 12 months- those flowing gas are still contributing to Unidentified Gas
    • Relevant data requested from Xoserve - all shipperless sites (including <12 months) - all >12 month sites visited (not just those found to be flowing gas)
    • Calculate “still flowing gas” rate from site visit data
    • Apply to <12 month sites
    • Carry out final calculation - all >12 month sites in report have been flowing gas for full 12 months - the <12 months sites still flowing gas will have been doing so for an average of 6 months
  • Shipperless Sites – Shipper Specific Report
    • Calculations as above
unidentified gas unregistered shipperless sites3
Unidentified Gas – Unregistered/Shipperless Sites
  • No Activity
    • Sites currently being processed
    • These will end up in one of the other categories
    • Split between those categories pro-rata before calculations carried out
  • Legitimately Unregistered
    • These sites are believed to have no meter
    • Hence they do no contribute to Unidentified Gas
unidentified gas igt csep registration delays
Unidentified Gas – IGT CSEP Registration Delays
  • Within CSEPs, sites cannot take gas without being registered
  • UG from this source comes from unregistered CSEPs only
    • Entire network not registered on Xoserve system
  • Regular meetings held with IGTs
  • Report on statistics
    • 32000 CSEPs
    • Approximately 1200 are currently unregistered
    • Down from 3000 in 2009
  • Get average CSEP composition from known (registered) CSEPs
  • Apply to unknown population to estimate consumption
unidentified gas shipper responsible theft
Unidentified Gas – Shipper-Responsible Theft
  • Data available for
    • Detected theft
    • Alleged theft
  • These are high and low limits for true theft
  • Two-yearly meter inspections ensure that unknown theft (ie theft that exists but has never been alleged) is limited
  • Changes in theft detection rates when shipper initiatives take place can be used to estimate likely value of true theft between upper and lower limits
  • It is recognised that true theft is very difficult to pinpoint
  • Final value will be one agreed to be reasonable by all parties
unidentified gas shrinkage error
Unidentified Gas – Shrinkage Error
  • Difference between initial estimate and final estimate of shrinkage
  • Can be positive or negative
  • Shrinkage calculated as defined in UNC
  • Most accurate models available are used
    • National Leakage Tests
    • Own Use Gas model
    • Standard Theft assumptions
  • Final shrinkage values recalculated after the event and RbD credited
  • Hence error of initial (pre-year) estimate already accounted for in process
unidentified gas meter error
Unidentified Gas – Meter Error

Metering takes place

  • At LDZ offtakes
  • At Supply Meter Points
    • DMs – daily
    • NDM LSP – usually monthly
    • SSP – less frequently
  • Meter errors only have an impact over time if they carry a long term aggregate bias
  • Potential effects can be positive or negative
  • If present, this is a correction to RbD rather than Unidentified Gas
unidentified gas meter error1
Unidentified Gas – Meter Error
  • SSP meters use a rubber diaphragm
    • These can warp over time
    • They are set up to be unbiased on average over their 20-year lifespan
    • SSP metering does not affect Unidentified Gas calculation anyway
  • LSP and larger meters use metal components
    • Regular maintenance
    • No warping over time
    • Therefore no long-term bias from this source
  • Meter error can be discounted from analysis
  • Backs up conclusions drawn in previous UNC Mods
unidentified gas unknown sites
Unidentified Gas – Unknown Sites
  • Sites that are taking gas that
    • Are not registered with a shipper
    • Do not even have a MPRN
  • These are unknown to the Xoserve system
  • Data has been requested on this subject
summary q a
Summary – Q/A
  • Any other areas of UG to consider?
  • Clarifications/Questions?
  • Can raise further questions/issues post meeting via