Code of Practice for coal seam gas well head emissions detection ...

Department of Employment, Economic Development and Innovation 

Code of Practice for coal seam gas 

well head emissions detection and 

reporting 

Version 2 - June 2011

Development of this Code 

This document has been developed at the request of the Department of Employment, Economic 

Development and Innovation Petroleum and Gas Inspectorate to provide a consistent industry 

approach 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. 

© 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. 

Code of Practice for CSG well head emissions, detection and reporting - Version 2 June 2011 2

Contents 

Introduction 4 

Objective 4 

Purpose of the Code 5 

Scope 5 

Responsibilities 5 

Relevant industry standards 5 

General CSG safety 6 

Definitions 6 

Code of Practice operational requirements 7 

Risk assessment 7 

Inspection frequency and procedure 7 

Standard leak classification 8 

Standard leak detection methodology 8 

Tester and instrument certification 9 

Remediation and notification 9 

Reportable leaks 9 

Internally reportable leaks 10 

Protection of CSG well site facilities 10 

Review of this Code of Practice 11 

Appendix 1 — Gas comparison table 12 

Appendix 2 — Definitions 13 

Appendix 3 — Petroleum and Gas Inspectorate contact details 15 


Introduction 

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

reticulated gas for Queensland’s domestic, commercial, manufacturing and industrial needs. It is 

piped throughout most of Queensland’s major cities and is essential to the State’s economy. CSG 

or natural gas (as it is commonly known) is commonly considered as the safest form of reticulated 

energy 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 from 

traditional natural gas wells or CSG wells can be liquefied and transported by ship to provide an 

important 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 have 

their own operating procedures with regard to well head emission classification and detection, this 

Code 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 being 

piped to market via cross country transmission pipelines. As CSG wells are generally located on 

grazing 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 to 

apply a rigorous, risk based approach to the safety of operations and possess a comprehensive 

asset integrity regime to minimise risks associated with the development and operations of CSG 

infrastructure. 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 Development 

and Innovation (DEEDI), as the gas safety regulator, is appropriately informed and the 

performance of the CSG industry’s performance on gas emission management is appropriately 

measured. 

Objective 

The 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, and 

3. notification procedure to the P&G Inspectorate for reportable emissions. 


Purpose of the Code 

This Code of Practice standardises the detection, remediation and reporting of gas emissions from 

CSG 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 internal 

risk 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 are 

identified, 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 Operator’s 

internal requirements are understood and implemented; and 

3. the life of CSG well site facilities is managed effectively through timely leak repair and 

periodic survey. 

Scope 

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

Responsibilities 

The CSG operator as defined in Appendix II and consistent with section 670 (6) and section 673 of 

the P&G Act, shall be accountable to ensure compliance with this Code of Practice. 

Relevant industry standards 

There 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 in 

CBD and metropolitan areas of all Australian and New Zealand cities. This urban environment 

provides 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 represents 

the most relevant and stringent standard to apply to identifying, classifying and managing gas 

leaks in rural gas fields. This Code of Practice has been drafted to meet or exceed the 

requirements of the AS/NZS: 4645.1:2008‘Gas distribution Network - Network Management’ 

standard. 

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 limit 

has been set for reportable leaks. The term LFL is explained in the following section on CSG 

safety. 

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 


stringent monitoring regime has been put in place in order to meet community expectations and 

ensure 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, with 

all leaks above 10% LFL being reportable. This exceeds the current standard level of 20% LFL at 

200mm distance used by some major operators in gas processing plants which have significant 

gas infrastructure often in confined spaces. 

General CSG safety 

CSG 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 in 

heaters, 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 business 

environments, natural gas is safely used in many other areas including transport fuels and as 

feedstock 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 and 

the 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% and 

15% 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 the 

smallest amount of gas that supports a self-propagating flame when mixed with air (or oxygen) and 

ignited. 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 hundred 

percent (100%) LFL denotes an atmosphere in which the gas concentration has reached its lower 

flammable limit. The relationship between percentage LFL and percent by volume differs from gas 

to 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 have 

measured gas concentrations as low as 10% LFL, which is an order of magnitude less than a 

flammable concentration. A 10% LFL is a very conservative standard and leaks of lower 

concentration of methane in an open air rural gas field environment are not regarded as a 

significant risk. 

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

Definitions 

Definitions for terms used in this Code of Practice are outlined in Appendix 2. 


Code of Practice operational requirements 

At 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 assessment 

CSG 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 reasonably 

practicable as required under the P&G Act. 

As part of their safety management plan as required under the P&G Act, each CSG operator must 

develop 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 and 

determining 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 procedure 

CSG operators must undertake routine visits to operational CSG well site facilities on a regular 

basis 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 competencyassured 

to identify gas leaks detected by their personal gas monitors, and to take appropriate 

actions 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 least 

once every five years. 

6. Undertake formal integrity audits on individual CSG well site facilities at an increased 

frequency as determined by the risk assessment and in consideration of previous 

audit/inspection findings for those specific facilities. 


Standard leak classification 

The following standard gas leak classification definition has been adopted and requires reportable 

leaks 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 the 

leak 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 a 

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

building 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 and 

rectification treatment in accordance with an individual company’s leak management plan and 

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

management plans. 

Standard leak detection methodology 

A 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 detector’s manufacturer’s instrument instructions for retest (eg a 

purge in clean atmosphere), the field technician shall retest a distance of 150mm from the 

leak 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 risk 

environments such as large scale semi enclosed gas processing and refining plants. 


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 with 

manufacturer’s instructions, and be capable of testing to a low reading of 1% LFL and have 

sensitivity of +/-0.5% LFL. 

Remediation and notification 

Reportable leaks 

In the event that a CSG operator detects a “Well Head Reportable Leak” at a CSG well site, the 

CSG 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 restrictions 

on 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 the 

leak 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, wellhead 

name, 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 after 

detection. 

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) or 

occupier(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 over 

steps 3a and 4 and complying with steps 3a and 4 must not compromise, impair or delay the 

operator’s 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 via 

the gasafe email (gassafe@dme.qld.gov.au) and must include the date of identification, nature 

and level of leak, wellhead name, number and location. 

a. Ensure that the gas leak is isolated, repaired (if possible), contained or otherwise made 

safe 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 the 

work. 

6. Remediation work must be conducted as follows: 

a. Only commence work after a suitable risk assessment has been undertaken and relevant 

safety procedures are followed including consideration of all the required Personal 

Protective Equipment (PPE) and emergency response materials. 


. For leaks identified on well equipment - higher order controls, such as containment by 

repair, must be implemented wherever possible. 

c. For leaks identified on well casings or adjacent to the well casing (where a work over rig 

is necessary to affect repair) - determine whether the leak requires immediate repair, or 

whether the risk can be adequately managed via other control measures until a work over 

of the well is scheduled for normal operational reasons. The risk assessment to 

determine the above must consider the location of the well, likely access to the well from 

landholders or the general public, and landholder/community concerns in relation to the 

leak. 

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 the 

well, 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 risk 

posed 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 ignition 

sources 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” (see 

definitions) at any CSG well site facility, the CSG operator must promptly respond in accordance 

with the actions specified in the relevant CSG operator’s ‘Leak Management Plan’ and other safety 

management 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 facilities 

Appropriate signage, barriers and/or security fencing to isolate CSG well site facilities must be in 

place 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 Explosive 

atmospheres 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 the 

general public; and 

2. The magnitude of the risk posed by the CSG well site facilities, which may be dependent on 

the 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 drilled 

and also after surface equipment is installed. 


The perimeter of all barrier fencing must be placed no closer than the appropriate classified 

hazardous area zone. 

Review of this Code of Practice 

This Code of Practice will be subject to review and revision every 24 months or in the event of 

significant change to operations or regulatory requirements. 


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 LPG 

respectively. 

The table provides a comparison of the different measurement units (LFL and PPM) and 

demonstrates 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 rise 

and 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 energy 

per 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 

Gas 

Specific 

Gravity 

[note 1, 3] 

Heating 

Value 

(mJ/m 3 ) 

[note 2,3] 

PPM at 

LFL 

PPM at 

10% LFL 

PPM at 

5% LFL 

Code of Practice for CSG well head emissions, detection and reporting - Version 2 June 2011 12 

PPM at 

1% LFL 

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 indicate 

that the gas is denser than air and can accumulate at ground level to form pools. Values 

given are at normal atmospheric temperature and pressure — 20 o C and 1 atmosphere 

respectively. 

[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.

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 a 

measurement distance of 150mm immediately above (and downwind) and surrounding the 

leak 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 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 treatment 

specified by each CSG operator’s procedures and risk based assessments. 

CSG Operator is defined as: 

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

activities on Authorities to Prospects (ATP’s), Petroleum Lease Applications (PLA’s) or Petroleum 

Leases (PL’s) 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 well 

head, pumping equipment, the production separator and interconnecting pipe work and fittings. 

Leak Management Plan is a plan that is part of the CSG operator’s safety management plan for 

leaks 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 


4. Reported 

and 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 for 

example checking filters, drains etc. 

CSG well site facility production operators must carry and monitor personal calibrated gas 

detectors 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 the 

CSG operator’s asset integrity process and details the condition of the CSG well site facility 

compared with it’s original design and operability specification. This audit should be completed by 

a 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 components 

of the CSG well site facility. 


Appendix 3 — Petroleum and Gas Inspectorate contact 

details 

Email: gassafe@deedi.qld.gov.au 

24/7 Emergency numbers for immediate reporting requirements: 

Southern region: 0419 888 575 

Central region: 0418 888 575 

Northern region: 0409 896 861 

General contact details: 

Southern region: 3238 3782 

Central region: 4938 4683 

Northern region: 4760 7402 

Head office: 3237 1626

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