Code of Practice for coal seam gas well head emissions detection and reporting

Transcription

1 Code of Practice for coal seam gas well head emissions detection and reporting Version 2 June 2011

2 Development of this Code This document has been developed at the request of the 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 23 June 2011 and effective 1 July State of Queensland, 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. The information contained herein is subject to change without notice. The Queensland Government 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.

3 Contents Introduction... 2 Objective... 2 Purpose of the Code... 2 Scope... 3 Responsibilities... 3 Relevant industry standards... 3 General CSG safety... 3 Definitions... 4 Code of Practice operational requirements... 5 Risk assessment... 5 Inspection frequency and procedure... 5 Standard leak classification... 5 Standard leak detection methodology... 6 Tester and instrument certification... 6 Remediation and notification... 6 Reportable leaks... 6 Extensions... 7 Internally reportable leaks... 8 Protection of CSG well site facilities... 8 Review of this Code of Practice... 8 Appendix 1 Gas comparison table... 9 Appendix 2 Definitions... 9 Appendix 3 Petroleum and Gas Inspectorate contact details Code of Practice for CSG well head emissions, detection and reporting Version 2 June

4 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) 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. Code of Practice for CSG well head emissions, detection and reporting Version 2 June

5 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: :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: :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 Code of Practice for CSG well head emissions, detection and reporting Version 2 June 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. Code of Practice for CSG well head emissions, detection and reporting Version 2 June

6 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 gasdetection 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 for CSG well head emissions, detection and reporting Version 2 June

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

8 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 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 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 riskbased 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 (e.g. 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 manufacturer s 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 Code of Practice for CSG well head emissions, detection and reporting Version 2 June

9 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 (gassafe@dnrm.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. b) 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. Code of Practice for CSG well head emissions, detection and reporting Version 2 June

10 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. Code of Practice for CSG well head emissions, detection and reporting Version 2 June

11 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 Heating value (mj/m 3 ) PPM at LFL PPM at 10% LFL PPM at 5% LFL PPM at 1% LFL [note 1, 3] [note 2,3] Methane (CSG) LPG (typical) ,000 5,300 2, ,000 2,100 1, 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 20oC 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 Code of Practice for CSG well head emissions, detection and reporting Version 2 June

12 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 (e.g. isolated, rectified, monitored) as determined by considering the risk and determining the appropriate controls and Code of Practice for CSG well head emissions, detection and reporting Version 2 June 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 e.g. 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 its 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. Code of Practice for CSG well head emissions, detection and reporting Version 2 June

13 Appendix 3 Petroleum and Gas Inspectorate contact details gassafe@dnrm.qld.gov.au 24/7 Emergency numbers for immediate reporting requirements: Northern region Central region Southern region General contact details: Northern region Central region Southern region Code of Practice for CSG well head emissions, detection and reporting Version 2 June