code practice well leak class

7/27/2019 Code Practice Well Leak Class

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Departme

ntofEmployment,EconomicDe

velopmentandInnovation

Code of Practice for coal seam gaswell head emissions detection and

reporting

Version 2 - June 2011


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Code of Practic e for CSG well head emiss ions , detection and reporting - Version 2 June 2011 2

The State of Queensland, Department of Employment, Economic Development and Innovation, 2011.

Except as permitted by the Copyright Act 1968, no part of this work may in any form or by any electronic,

mechanical, photocopying, recording, or any other means be reproduced, stored in a retrieval system or be

broadcast or transmitted without the prior written permission of the Department of Employment, Economic

Development and Innovation. The information contained herein is subject to change without notice. The

copyright owner shall not be liable for technical or other errors or omissions contained herein. The reader/user

accepts all risks and responsibility for losses, damages, costs and other consequences resulting directly or

indirectly from using this information.

Development of th is Code

This document has been developed at the request of the Department of Employment, EconomicDevelopment and Innovation Petroleum and Gas Inspectorate to provide a consistent industryapproach to wellhead leak testing, reporting and remediation.

The Code was developed by an industry working group from October 2010 through to March 2011

and has been overseen and endorsed by the Inspectorate. The Code has been called up in the

Petroleum and Gas (Production and Safety) Regulation 2004 as a preferred standard.

The Code will be reviewed by an industry working group within 24 months.

Version 2 makes changes to include notification requirements to landholders. Published 23June

2011 and effective 1 July 2011.


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Contents

Introduction 4Objective 4Purpose of the Code 5Scope 5Responsibilities 5Relevant industry standards 5General CSG safety 6Definitions 6Code of Practice operational requirements 7Risk assessment 7Inspection frequency and procedure 7Standard leak classification 8Standard leak detection methodology 8Tester and instrument certification 9Remediation and notification 9Reportable leaks 9Internally reportable leaks 10Protection of CSG well site facilities 10Review of this Code of Practice 11Appendix 1 Gas comparison table 12Appendix 2 Definit ions 13Appendix 3 Petroleum and Gas Inspectorate contact details 15


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IntroductionCoal Seam Gas (CSG) is an important energy source for Queensland and supplies around 80% of

reticulated gas for Queenslands domestic, commercial, manufacturing and industrial needs. It is

piped throughout most of Queenslands major cities and is essential to the States economy. CSGor natural gas (as it is commonly known) is commonly considered as the safest form of reticulatedenergy used for domestic purposes. Natural gas is also reticulated throughout almost every major

city in the world and is relied upon to drive economic growth.

CSG is a natural gas (consisting almost entirely of methane) that is currently being extracted from

coal seams in the Bowen and Surat Basins in Queensland. Natural gas, either produced fromtraditional natural gas wells or CSG wells can be liquefied and transported by ship to provide animportant income for the state and provide considerable employment for both regional and

metropolitan based workers.

CSG wells and their associated facilities are rated as low risk for emissions due to rigorous design

standards, robust safety obligations and strong governance programs. While CSG operators havetheir own operating procedures with regard to well head emission classification and detection, thisCode of Practice provides a consistent best practice minimum standard for identifying, classifying,

rectifying and reporting well head gas emissions.

CSG is extracted from an increasing number of unmanned gas wells connected to a network of

underground gathering pipelines. Gas is then filtered, compressed and dehydrated before beingpiped to market via cross country transmission pipelines. As CSG wells are generally located ongrazing or cultivated land, land owners and occupiers have raised concerns about how the CSG

industry identifies and manages potential gas leakage at CSG well site facilities.

The Petroleum and Gas (Production and Safety) Act 2004 (P&G Act) requires CSG operators toapply a rigorous, risk based approach to the safety of operations and possess a comprehensiveasset integrity regime to minimise risks associated with the development and operations of CSGinfrastructure. Compliance with this legislation will result in an extremely low level of risk from gas

emissions at CSG well sites.

The reporting resulting from this Code of Practice will ensure that the Petroleum and Gas

Inspectorate (P&G Inspectorate) within the Department of Employment, Economic Developmentand Innovation (DEEDI), as the gas safety regulator, is appropriately informed and theperformance of the CSG industrys performance on gas emission management is appropriately

measured.

ObjectiveThe objective of this Code of Practice is to set a standard:

1. methodology to detect gas leaks,2. procedure to classify and action reportable leaks, and3. notification procedure to the P&G Inspectorate for reportable emissions.


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Purpose of the CodeThis Code of Practice standardises the detection, remediation and reporting of gas emissions fromCSG well site facilities, and places particular emphasis on community safety.

The Code is designed to be considered and used in conjunction with the CSG Operators internalrisk assessment processes and operating procedures under their safety management systems. It

adopts a standard process for monitoring, identifying and managing gas leaks from CSG well site

facilities in Queensland. The Code ensures that emissions associated with gas leaks areidentified, responded to and classified in a consistent manner, and that wells are monitored

effectively by the CSG Operators.

The Code will help to ensure that:

1. risk to the public and CSG workers is managed to a level that is as low as reasonably

practicable;

2. regulatory and applicable Australian Standard requirements, as well as the Operatorsinternal requirements are understood and implemented; and3. the life of CSG well site facilities is managed effectively through timely leak repair and

periodic survey.

ScopeThis Code of Practice applies to all CSG operators in Queensland.

ResponsibilitiesThe CSG operator as defined in Appendix II and consistent with section 670 (6) and section 673 ofthe P&G Act, shall be accountable to ensure compliance with this Code of Practice.

Relevant industry standardsThere is currently no standard specifically for the identification and management of leaks in

petroleum 'upstream' or CSG facilities.

However, AS/NZS: 4645.1:2008 Gas distribution Network - Network Management standard

describes operational and leakage management obligations for natural gas distribution networks inCBD and metropolitan areas of all Australian and New Zealand cities. This urban environmentprovides greater risks and consequences for leaks than the rural gas field environment, and sets a

high benchmark for the management of leaks for the CSG industry.

Therefore, this standard has been adopted as the basis for this Code of Practice, as it representsthe most relevant and stringent standard to apply to identifying, classifying and managing gasleaks in rural gas fields. This Code of Practice has been drafted to meet or exceed therequirements of the AS/NZS: 4645.1:2008Gas distribution Network - Network Managementstandard.

This Code of Practice similarly adopts a conservative approach to the classification of reportable

leaks. Under this Code, a threshold gas content of 10% Lower Flammable Limit (LFL) lower limithas been set for reportable leaks. The term LFL is explained in the following section on CSGsafety.

This sets a more rigorous standard than the personal lower limit level of 20%-25% LFL commonly

used by gas and emergency workers responding to or potentially exposed to gas leaks. This does

not mean that the risk of gas emissions is greater in gas fields; rather it means that a more


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stringent monitoring regime has been put in place in order to meet community expectations andensure community confidence in the leak monitoring and gas field safety regime.

A standard leak measuring methodology has been adopted for the industry under this Code of

Practice. This methodology requires gas/air content to be measured at 150mm from source, withall leaks above 10% LFL being reportable. This exceeds the current standard level of 20% LFL at200mm distance used by some major operators in gas processing plants which have significantgas infrastructure often in confined spaces.

General CSG safetyCSG is a safe energy source that is a by-product of the natural conversion of plant material to coal.CSG consists mostly of methane which, like other forms of natural gas, can be used as a fuel inheaters, stoves and hot water systems in homes and businesses. Methane is non-toxic and is only

flammable when the gas concentration is between 5% and 15% per cent of the total gas/air

mixture. CSG is lighter than air, meaning it will rise naturally and quickly dilute and dissipate into

the air in an outdoor environment. In addition to its application in domestic and businessenvironments, natural gas is safely used in many other areas including transport fuels and asfeedstock or fuel for industrial plants.

CSG well site facilities are constructed to Australian or International Standards where applicable.

These facilities are pressure tested prior to commissioning to verify the integrity of the facilities andthe CSG operators conduct routine monitoring to ensure ongoing safe operation of the facilities.

For CSG to reach a flammable state, it must first form a concentration level of between 5% and15% of gas in air. A typical potential gas leak at a well head site is likely to emanate from a gas

flange or screwed joint. This type of leak is generally insufficient to support combustion.

The lower explosive limit (LEL) or lower flammable limit (LFL) of a combustible gas describes thesmallest amount of gas that supports a self-propagating flame when mixed with air (or oxygen) andignited. In gas-detection systems, the amount of gas present is specified as a percentage (%) LFL.

Zero percent (0%) LFL denotes an atmosphere that is free from a combustible gas. One hundredpercent (100%) LFL denotes anatmosphere in which the gas concentration has reached its lowerflammable limit. The relationship between percentage LFL and percent by volume differs from gasto gas (for example liquid petroleum gas (LPG) has a different LFL to CSG).

This Code of Practice describes the actions that CSG operators must undertake for leaks that havemeasured gas concentrations as low as 10% LFL, which is an order of magnitude less than aflammable concentration. A 10% LFL is a very conservative standard and leaks of lowerconcentration of methane in an open air rural gas field environment are not regarded as asignificant risk.

Appendix 1 provides a comparison of the properties of CSG compared with LPG.

DefinitionsDefinitions for terms used in this Code of Practice are outlined inAppendix 2.


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Code of Practice operational requirementsAt a minimum, CSG Operators must comply with the following requirements to ensure that risks

from gas leaks at CSG well site facilities are reduced to as low as reasonably practicable.

Risk assessmentCSG operators must carry out a risk assessment to identify the risks posed by leaks from CSG well

site facilities and implement appropriate actions to reduce those risks to as low as reasonablypracticable as required under the P&G Act.

As part of their safety management plan as required under the P&G Act, each CSG operator mustdevelop a risk-based management plan (Leak Management Plan) for leaks from CSG wells and

CSG well site facilities to ensure that emissions are:

1. Identified;2. Classified

3. Controlled (e.g. isolated, rectified, monitored) as determined by considering the risk anddetermining the appropriate controls, and

4. Reported,

and there are systems in place and initiated to ensure the control actions are completed.

This Code does not remove the obligation for adequate risk assessment and management to be

undertaken.

Inspection frequency and procedureCSG operators must undertake routine visits to operational CSG well site facilities on a regularbasis in accordance with their operating and maintenance plans.

CSG Operators must at a minimum:

1. Ensure that CSG well site facility production operators carry and monitor personal calibrated

gas detectors during every routine operational visit to CSG well site facilities.2. Ensure that CSG well site facility production operators are properly trained and competency-

assured to identify gas leaks detected by their personal gas monitors, and to take appropriateactions in line with this Code of Practice, during routine operational visits to CSG well site

facilities.3. Ensure that CSG well site facility production operators use calibrated gas monitors to

investigate and classify any audible leaks at CSG well site facilities, and that the appropriate

actions to manage those leaks are taken in line with this Code of Practice.4. Ensure formal integrity audits are conducted on 20% of the total number of CSG well site

facilities per annum.

5. Ensure a formal integrity audit is conducted on every operating CSG well site facility at leastonce every five years.

6. Undertake formal integrity audits on individual CSG well site facilities at an increasedfrequency as determined by the risk assessment and in consideration of previous

audit/inspection findings for those specific facilities.


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Standard leak classificationThe following standard gas leak classification definition has been adopted and requires reportableleaks to be notified to the P&G Inspectorate.

A Well Head Reportable Leak is defined as:

1. An emission due to an unplanned release from a CSG well site facility that, at a

measurement distance of 150mm immediately above (and downwind) and surrounding theleak source in an open air environment above ground position; gives a sustained LFL

reading greater than 10% of LFL for a 15 second duration.

2. The following incidents/circumstances also fall under the definition and require CSG

operators to notify the P&G Inspectorate:a. an unplanned hydrocarbon gas release reported by the emergency services, a public

authority or member of the general public;b. an unplanned hydrocarbon gas release resulting in an incident involving fire or injury;

c. an unplanned hydrocarbon gas release which receives media attention, and

d. an unplanned release with the potential for significant escalation close enough to abuilding or other confined space and large enough that gas is likely to enter anybuilding or confined space.

An unplanned gas release that falls outside of the above parameters will be classified as an Internally Reportable Well Head Leak and will be subject to reporting procedures andrectification treatment in accordance with an individual companys leak management plan and

other safety management plan risk-based assessments and requirements in other safety

management plans.

Standard leak detection methodologyA suitably trained and competent field technician will survey for gas leaks by placing the probe of

the gas detector immediately adjacent to but not touching (approximately 10-20mm away) all

potential sources of leakage at the well facility.

Should an indication of gas be found, the field technician will:

1. Record the % LFL or % methane sustained for 15 seconds.

2. After complying with the detectors manufacturers instrument instructions for retest (eg a

purge in clean atmosphere), the field technician shall retest a distance of 150mm from theleak source in all directions and determine the highest leak zone (potentially immediately

above and in a downwind situation from the source).3. The highest confirmed % LFL of gas sustained for 15 seconds with the gas probe held at

150mm from the potential source must be recorded.

4. The source of leak must be clearly identified and recorded.

A reportable well head leak is defined in the Standard leak classification section above.

This standard exceeds currently accepted industry standards of detection in higher riskenvironments such as large scale semi enclosed gas processing and refining plants.


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Tester and instrument certification

All gas leak surveys will be conducted by trained personnel using industry-accepted gas detection

instruments calibrated by certified testers (ie NATA approved) in accordance with the

manufacturers requirements. Gas detectors must be maintained and tested in accordance withmanufacturers instructions, and be capable of testing to a low reading of 1% LFL and havesensitivity of +/-0.5% LFL.

Remediation and notificationReportable leaks

In the event that a CSG operator detects a Well Head Reportable Leak at a CSG well site, theCSG operator must:

1. Comply with the CSG operators safety management system requirements for risk assessment

and emergency response;

2. Immediately establish an exclusion zone around the leak and impose appropriate restrictionson access to the exclusion zone, along with any other necessary immediate controls;

3. Immediately notify any leaks at or over the LFL (i.e. 100% LFL or greater at 150mm from theleak source) to the P&G Inspectorate via their 24/7 emergency numbers (see Appendix 3).

a. This notification must include the date of identification, nature and level of leak, wellheadname, number and location as well as initial steps taken to minimise the risk.

b. Leaks over LFL must be repaired or made safe as soon as practicable immediately afterdetection.

4. Immediately:a. Notify the land owner or occupier of the property on which any uncontrolled leaks from

CSG well site facilities and related infrastructure (of 100% LFL or greater at 150mm from

the leak source) are identified.b. If the reportable leak zone (gas concentrations greater than 10%LFL) from an

uncontrolled leak is or is likely to impact on adjoining properties then the landowner(s) oroccupier(s) of those properties must also be notified.

Note: Step 2 and step 3b in terms of immediately safely making the site safe take priority oversteps 3a and 4 and complying with steps 3a and 4 must not compromise, impair or delay theoperators actions to immediately make the site safe and establish exclusion zones.

5. Notify the Petroleum and Gas Inspectorate in writing within 24 hours of the detection of any

leak within the reportable leak range (10% LFL and above). This notification is to be made viathe gasafe email ([email protected]) and must include the date of identification, natureand level of leak, wellhead name, number and location.

a. Ensure that the gas leak is isolated, repaired (if possible), contained or otherwise madesafe within 48 hours of detection of the leak.

b. In the event of this deadline being unachievable, the CSG operator must notify the P&G

Inspectorate of the reason for the delay and provide a target date for completion of thework.

6. Remediation work must be conducted as follows:

a. Only commence work after a suitable risk assessment has been undertaken and relevantsafety procedures are followed including consideration of all the required PersonalProtective Equipment (PPE) and emergency response materials.


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b. For leaks identified on well equipment - higher order controls, such as containment byrepair, must be implemented wherever possible.

c. For leaks identified on well casings or adjacent to the well casing (where a work over rigis necessary to affect repair) - determine whether the leak requires immediate repair, orwhether the risk can be adequately managed via other control measures until a work overof the well is scheduled for normal operational reasons. The risk assessment todetermine the above must consider the location of the well, likely access to the well fromlandholders or the general public, and landholder/community concerns in relation to theleak.

7. Provide a written close-out report to the P&G Inspectorate within 96 hours of detection of the

leak, specifying the date of identification, nature and level of leak, location and name of thewell, the rectification actions taken or proposed and the current status of the leak (e.g.

isolated, repaired, etc).

8. If remediation is delayed for any reason then a final close out report must be provided when all

work is completed.

The P&G Inspectorate may upon review of the report and risk assessment require further

information or action in accordance with its enforcement policy and regulatory role.

Extensions

If a risk assessment determines that the risks of immediately repairing a leak exceed the riskposed by the leak, this can be considered as grounds for extension of the 48 hour remediation

period, provided that other measures to mitigate the risk are undertaken (e.g. ensuring no ignitionsources or personnel are permitted in the exclusion zone). The P&G Inspectorate must be notified

(before the expiry of the 48 hour remediation period) of the proposed delay.

Internally reportable leaks

In the event that a CSG operator detects an Internally Reportable Well Head Leak (seedefinitions) at any CSG well site facility, the CSG operator must promptly respond in accordance

with the actions specified in the relevant CSG operators Leak Management Plan and other safetymanagement plan requirements.

On an annual basis (via the annual safety report), a summary of all well head reportable leaks and

internally reportable leaks must be provided to the P&G Inspectorate.

Protection of CSG well site facilit ies

Appropriate signage, barriers and/or security fencing to isolate CSG well site facilities must be inplace for all well site facilities as determined by the CSG operators risk assessment and

management. The risk assessment must be consistent with AS/NZS:60079 Explosiveatmospheres Part 10.1:2009 and will consider:

1. Risks posed by third parties and the general public based on proximity of the CSG well site

facilities the ownership of land, and the accessibility of the CSG well site facilities to thegeneral public; and

2. The magnitude of the risk posed by the CSG well site facilities, which may be dependent onthe type of well completion the equipment/facilities installed at these sites and the pressure,

flow rate and composition of the gas contained by the facilities.

CSG operators must ensure that all required fencing and signage is in place after the well is drilledand also after surface equipment is installed.


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The perimeter of all barrier fencing must be placed no closer than the appropriate classifiedhazardous area zone.

Review of this Code of PracticeThis Code of Practice will be subject to review and revision every 24 months or in the event ofsignificant change to operations or regulatory requirements.


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Appendix 1 Gas comparison table

The table below compares the specific gravity, energy content and the PPM (parts per million)

values corresponding to 100%, 10%, 5% and 1% LFL readings for CSG (methane) and LPGrespectively.

The table provides a comparison of the different measurement units (LFL and PPM) anddemonstrates that compared to LPG, which is a gas in common domestic use, CSG/methane

represents a much lower risk although both gases when managed appropriately are safe to use.

For example, the gravity for CSG/methane is much less than one, indicating that methane will riseand disperse into the atmosphere when released and will not form pools at ground level as in the

case of LPG.

The heating value of LPG is much higher than CSG/methane, meaning LPG emits more energyper cubic metre of gas when it is burnt.

The PPM values indicate that LPG has a greater risk of flammability even at substantially lower

levels of gas concentration in air.

This table is for informative purposes only.

Gas Comparison Table

GasSpecific

Gravity

HeatingValue

PPM atLFL

PPM at

10% LFL

PPM at

5% LFL

PPM at

1% LFL

[note 1, 3](mJ/m3)

[note 2,3]

Methane (CSG) 0.554 38.7 53,000 5,300 2,650 530

LPG (typical) 1.609 95.5 21,000 2,100 1,050 210

Notes: [1] Specific gravity is the density of the gas relative to air. Values greater than one indicatethat the gas is denser than air and can accumulate at ground level to form pools. Valuesgiven are at normal atmospheric temperature and pressure 20oC and 1 atmosphererespectively.

[2] Approximate gross heating value.[3] Values in columns 2 and 3 are an average calculated from maximum and minimum

Australian pipeline quality natural gas specifications.


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Appendix 2 Definitions

Well Head Reportable Leak is defined as:

1. An emission due to an unplanned release from a CSG well site facility that, at ameasurement distance of 150mm immediately above (and downwind) and surrounding the

leak source in an open air environment above ground position; gives a sustained LFLreading greater than 10% of LFL for a 15 second duration.

2. The following incidents/circumstances also fall under the definition and require CSGoperators to notify the P&G Inspectorate:

a) an unplanned hydrocarbon gas release reported by the emergency services, a public

authority or member of the general public;

b) an unplanned hydrocarbon gas release resulting in an incident involving fire or injury;c) an unplanned hydrocarbon gas release which has media attention, and

d) an unplanned hydrocarbon gas release with the potential for significant escalation close

enough to a building or other confined space and large enough that gas is likely to enter

any building or confined space.

Internally Reportable Well Head Leak is defined as:

Any leak of gas from a CSG well site facility that falls outside of the above definition of wellhead

reportable leak. These leaks will be subject to reporting procedures and rectification treatmentspecified by each CSG operators procedures and risk based assessments.

CSG Operatoris defined as:

The company that is responsible for the safe operation and management of CSG authorised

activities on Authorities to Prospects (ATPs), Petroleum Lease Applications (PLAs) or PetroleumLeases (PLs) under section 670(6) of the P&G Act. The operator is defined under section 673 of

the P&G Act.

CSG Well is defined as:

A well that is constructed to allow gas from coal seams to migrate into the well, and which may

contain pressurised hydrocarbon gas (eg methane).

CSG Well Site Facility is defined as:

The above ground equipment located in the immediate proximity of a CSG well and connected to

that CSG well, which contains or may contain pressurised hydrocarbon gas. It includes the wellhead, pumping equipment, the production separator and interconnecting pipe work and fittings.

Leak Management Plan is a plan that is part of the CSG operators safety management plan forleaks from CSG wells and CSG well site facilities to ensure that emissions are:

1. Identified;2. Classified;3. Controlled (eg isolated, rectified, monitored) as determined by considering the risk and

determining the appropriate controls; and


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4. Reportedand there are systems in place and initiated to ensure the control actions are completed.

Routine Operational Visit is defined as:

A routine check or visit by production operators to complete an operational check or complete

planned or unplanned maintenance. These visits can include normal operational functions forexample checking filters, drains etc.

CSG well site facility production operators must carry and monitor personal calibrated gasdetectors during every routine operational visit to CSG well site facilities.

Formal Integrity Audit is defined as:

A formal inspection of the integrity of a CSG well site facility. This inspection is required by theCSG operators asset integrity process and details the condition of the CSG well site facility

compared with its original design and operability specification. This audit should be completed bya competent person and would make observations on the integrity and quality of existing CSG well

site facility. This audit will include (as a minimum), a comprehensive leak survey of all componentsof the CSG well site facility.


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Appendix 3 Petroleum and Gas Inspectorate contactdetails

Email: [email protected]

24/7 Emergency numbers for immediate reporting requirements:

Southern region: 0419 888 575Central region: 0418 888 575

Northern region: 0409 896 861

General contact details:

Southern region: 3238 3782Central region: 4938 4683

Northern region: 4760 7402Head office: 3237 1626

code practice well leak class

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