Code of Practice For the construction and abandonment of coal seam gas and petroleum wells, and associated bores in Queensland Petroleum and Gas Inspectorate Version 1 1 September 2018 Table: Document history Version Date of publication Date of effect Key changes number V1 1 September 2018 1 September 2018 This Code is a consolidation of the Code of Practice for the construction and abandonment of coal seam gas wells and associated bores in Queensland, Edition 3.0, 19 May 2017 and the Code of Practice for the construction and abandonment of petroleum wells and associated bores in Queensland, Edition 1.0, 3 Mar 2016, with some revisions to align with the commencement of Petroleum and Gas (Safety) Regulation 2018 This publication has been complied by the Petroleum and Gas Inspectorate, Resources Safety and Health, Department of Natural Resources, Mines and Energy, with significant input from the Queensland petroleum lease operators and stakeholders. © State of Queensland, 2018 The Queensland Government supports and encourages the dissemination and exchange of its information. 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Table of contents 1 Overview ........................................................................................................................................ 1 1.1 Background .................................................................................................................................... 1 1.1.1 Other relevant legislations ............................................................................................ 1 1.2 Purpose .......................................................................................................................................... 2 1.3 Scope and application .................................................................................................................... 2 1.3.1 Scope of this Code of Practice...................................................................................... 2 1.3.2 Alternate means of compliance ..................................................................................... 3 1.3.3 Application ..................................................................................................................... 3 2 Coal seam gas wells .................................................................................................................... 4 2.1 General description of coal seam gas drilling activities ................................................................. 4 2.1.1 Introduction ................................................................................................................... 4 2.1.2 Well construction process ............................................................................................. 5 2.1.3 Site Identification and location ...................................................................................... 5 2.1.4 Risk assessment ........................................................................................................... 6 2.2 Principles, means of compliance and good industry practices ...................................................... 6 2.2.1 Well design .................................................................................................................... 6 2.2.2 Casing ........................................................................................................................... 8 2.2.3 Cementing ..................................................................................................................... 9 2.2.4 Wellheads ................................................................................................................... 13 2.2.5 Well control equipment ............................................................................................... 13 2.2.6 Drilling fluids ................................................................................................................ 14 2.2.7 Evaluation, logging, testing and coring ....................................................................... 15 2.2.8 Well integrity management ......................................................................................... 17 2.2.9 Abandonment of wells, bores and other drill holes ..................................................... 19 2.2.10 Recording and reporting data ..................................................................................... 28 3 Petroleum wells .......................................................................................................................... 30 3.1 General description of petroleum well life cycle activities ............................................................ 30 3.1.1 Introduction ................................................................................................................. 30 3.1.2 Outline of the well life cycle phases ............................................................................ 30 3.1.3 Site identification and location .................................................................................... 31 3.1.4 Risk management/risk identification ........................................................................... 32 3.1.5 Management of change .............................................................................................. 32 3.2 Principles, means of compliance and good industry practices .................................................... 32 3.2.1 Well life cycle records, reporting and notification ........................................................ 32 3.2.2 Well design and well barriers ...................................................................................... 33 3.2.3 High pressure high temperature petroleum well design ............................................. 35 3.2.4 Working with hydrogen sulphide (H2S) ....................................................................... 36 3.2.5 Casing and tubing ....................................................................................................... 38 3.2.6 Primary cementing ...................................................................................................... 41 3.2.7 Aquifer isolation........................................................................................................... 46 3.2.8 Wellheads ................................................................................................................... 47 3.2.9 Well control ................................................................................................................. 48 3.2.10 Drilling fluids ................................................................................................................ 49 3.2.11 Well evaluation, logging, testing and coring ............................................................... 52 3.2.12 Hydraulic stimulation/flow-back operations ................................................................. 54 3.2.13 Well integrity Management ......................................................................................... 56 3.2.14 Workover and Intervention .......................................................................................... 57 3.2.15 Well suspension and abandonment ............................................................................ 58 3.2.16 Recording and reporting data ..................................................................................... 65 4 Additional and alternative requirements for water bores ...................................................... 66 4.1 Introduction ................................................................................................................................... 66 4.2 General water bore construction requirements ............................................................................ 66 4.2.1 Principles ..................................................................................................................... 66 4.2.2 Means of compliance .................................................................................................. 66 4.3 Maximising water entry for constructed water bores .................................................................... 67 4.3.1 Principles ..................................................................................................................... 67 4.3.2 Means of compliance .................................................................................................. 67 4.3.3 Good industry practice ................................................................................................ 67 4.4 Water bore development .............................................................................................................. 69 4.4.1 Principles ..................................................................................................................... 69 4.4.2 Good industry practice ................................................................................................ 69 4.5 Headworks for water bores .......................................................................................................... 70 4.5.1 Principles ..................................................................................................................... 70 4.5.2 Means of compliance .................................................................................................. 70 4.5.3 Good industry practice ................................................................................................ 70 4.6 Single casing string, single aquifer bores ..................................................................................... 70 4.6.1 Principles ..................................................................................................................... 70 4.6.2 Means of compliance .................................................................................................. 70 4.6.3 Good industry practice ................................................................................................ 71 4.7 Areas where groundwater is corrosive ......................................................................................... 71 4.7.1 Principles ..................................................................................................................... 71 4.7.2 Means of compliance .................................................................................................. 71 4.8 Injection bores .............................................................................................................................. 71 4.8.1 Principles ..................................................................................................................... 71 4.8.2 Means of compliance .................................................................................................. 72 4.9 Conversion of CSG & petroleum wells to water bores ................................................................. 72 4.9.1 Principles ..................................................................................................................... 72 4.9.2 Means of compliance .................................................................................................. 72 4.9.3 Good industry practice ................................................................................................ 72 Appendix 1 – Glossary ....................................................................................................................... 73 Appendix 2 – Industry standards ...................................................................................................... 79 Appendix 3 – Cooper / Eromanga Basin Aquifers ........................................................................... 82 Appendix 4 - Examples of standard Surat abandonment schematics .......................................... 83 Appendix 5 – References ................................................................................................................... 84 Table of figures Figure 1: Illustration of the scope of this Technical Specification ......................................................... 17 Figure 2: Open hole/ uncased hole section (no lost circulation and not approved for commingling) ... 22 Figure 3: Cased hole section ................................................................................................................ 23 Figure 4: Casing show with open hole below ....................................................................................... 24 Figure 5: Casing shoe with open hole/un-cemented liner below (with lost circulation) ........................ 25 Figure 6: Cut and recovered casing/liner or Production liner laps ....................................................... 26 Figure 7: Perforated casing ................................................................................................................... 27 Figure 8: Cement encased casing - well barrier ................................................................................... 60 Figure 9: Open hole / uncased hole section ......................................................................................... 61 Figure 10: Cased hole section .............................................................................................................. 61 Figure 11: Casing shoe with open hole below ...................................................................................... 62 Figure 12: Casing shoe with open hole below (with lost circulation) .................................................... 62 Figure 13: Cut and recovered casing .................................................................................................... 63 Figure 14: Perforated casing ................................................................................................................. 63 Figure 15: Production or HPHT zone Liner Laps .................................................................................. 64 Table of tables Table: Document history ......................................................................................................................... 2 Table 1: Typical design factors used in the hydrocarbon industry ........................................................ 39 Table 2: Property and primary cement criteria ...................................................................................... 42 Table 3: Primary cementing slurry design considerations .................................................................... 43 Table 4: Verification and evaluation recommendations for primary cement jobs ................................. 44 Table: Terms and definitions ................................................................................................................. 73 1 Overview 1.1 Background In Queensland, petroleum and gas safety is regulated under the Petroleum and Gas (Production and Safety) Act 2004 (P&G Act), and the Petroleum and Gas (Safety) Regulation 2018 (P&G Regulation). This legislation is administered and enforced by the Petroleum and Gas Inspectorate (the Inspectorate). Under the legislation, petroleum tenure applies to both conventional and unconventional resources including coal seam gas (CSG). In practice, there are technical differences between a well drilled for CSG and a conventional resource. This consolidated Code of Practice for the construction and abandonment of coal seam gas and petroleum wells and associated bores in Queensland comprises the former construction and abandonment code for CSG wells requirements (in Part 2) and the former construction and abandonment code for petroleum wells requirements (in Part 3) and combines the associated bore requirements in Part 4. Accordingly, this Code addresses CSG wells and conventional petroleum wells separately. For the purpose of this Code, the terms ‘CSG well’ and ‘petroleum well’ are used, and mean the following: • ‘CSG well’ means a prescribed well, as defined in the P&G Regulation, that is drilled on a petroleum authority to explore for or produce natural gas from a coal seam reservoir. • ‘Petroleum well’ means a petroleum well, as defined in the P&G Act, other than a CSG well. Well integrity is fundamental to ensuring sustainable petroleum production, ensuring risk can be managed to an acceptable level and protecting aquifers during the well life cycle. This Code addresses safety and environmental issues in the construction and abandonment (decommissioning) of petroleum and CSG wells and associated bores. The P&G Regulation establishes that the means of compliance in this Code are to be complied with for the drilling, converting and abandoning of petroleum wells, CSG wells and water bores. 1.1.1 Other relevant legislations In Queensland, petroleum activities are also subject to the Environmental Protection Act 1994. Under an environmental authority, petroleum tenure holders are generally required to monitor, identify and manage potential risks to the environment. The Water Act 2000 (the Water Act) provides a regulatory framework for petroleum tenure holders to monitor, assess and manage the impacts of their underground water rights on water bores, aquifers and springs. Specification for water bores constructed under the Water Act are provided for in the Minimum Construction Requirements for Water Bores in Australia (MCRWBA) and the Minimum Standards for the Construction and Reconditioning of Water Bores that Intersect the Sediments of Artesian Basins in Queensland (MSWBIAB). Code of Practice for the construction and abandonment of coal seam gas and petroleum wells, and associated bores in Queensland 1 1.2 Purpose The purpose of this Code is to ensure that all petroleum wells, CSG wells and associated bores are constructed, maintained and abandoned to a minimum acceptable standard resulting in long-term well integrity, containment of petroleum and the protection of groundwater resources. This Code identifies industry standards and good oilfield practice for oil and gas well design. It provides a way for petroleum tenure holders to comply with their obligations under Queensland’s petroleum legislation. However, it is not intended to discourage or prevent petroleum tenure holders from adopting an alternative means of achieving a level of risk that is equal to or less than the level of risk that would be achieved by complying with this Code. The design of this Code complements the petroleum tenure holder's internal risk assessment processes, operating standards and procedures by outlining a recommended process to ensure that: a) the environment and groundwater resources are protected b) risk to the public and workers is managed to a level as low as reasonably practicable c) regulatory and applicable Australian and international standards/requirements, as well as the petroleum tenure holder's standards, are understood and implemented where appropriate d) the life of a petroleum well, CSG well or associated bore is managed effectively through appropriate design and construction techniques and ongoing well integrity monitoring. 1.3 Scope and application 1.3.1 Scope of this Code of Practice This Code applies to petroleum wells, CSG wells and water bores constructed by petroleum tenure holders on their tenures for both conventional and unconventional oil and gas exploration and production. It covers conversion of CSG wells and petroleum wells to water bores. This Code covers all petroleum well types including exploration, appraisal, monitoring, injection and production wells, and water bores, including water observation, water supply and water injection bores. This Code applies to the following well life cycle phases: a) preliminary well planning and well design b) well construction (up to the production wing valve of the well head/Christmas tree) c) well evaluation and hydraulic fracture stimulation activities d) well integrity management e) well suspension and abandonment f) construction of new water bores by petroleum tenure holders g) conversion of petroleum wells and CSG wells to water bores. Within those stages, it considers equipment and material selection, risk assessment (both safety and environment), industry practices, monitoring and reporting. This Code does not: a) address the manufacture or the certification of drilling rigs or associated equipment b) refer to any necessary technical training of the various operatives. Code of Practice for the construction and abandonment of coal seam gas and petroleum wells, and associated bores in Queensland 2 1.3.2 Alternate means of compliance This Code addresses industry standards and good oilfield practice for oil and gas well construction, conversion and abandonment, and Australian standards for water bore construction and abandonment. If a petroleum tenure holder proposes an alternate means of compliance to the stated means of compliance in this Code, the proposal is to be submitted to the Chief Inspector, Petroleum and Gas for written approval. Alternate means of compliance is authorised by written approval from the Chief Inspector. 1.3.3 Application The contents of this Code falls into the following categories: a) Principles: these are the fundamental requirements that must be adhered to during the lifecycle of the well or bore. b) Means of compliance: these are the requirements that are enforceable by the regulator and must be complied with. By adhering to these requirements, the well or bore will meet the Principles. c) Good industry practices: these are recommended practices, methods and techniques to assist petroleum tenure holders to satisfy the means of compliance. These are not in themselves means of compliance or principles. The terms should or may are used for good industry practice recommendations. Where there is a conflict between this Code and the safety requirements or other relevant provisions in the P&G Act or P&G Regulation, the provisions of the P&G Act or P&G Regulation (as the case may be) prevail. Compliance with this Code is directed at the petroleum tenure holder, being the entity responsible for management of the safe operations of exploring for and producing petroleum on the land to which a petroleum tenure applies. The petroleum tenure holder should ensure that all parties undertaking work covered by this Code (e.g. drilling contractors) also comply with it. Part 4 of this Code: Additional and alternative requirements for water bores, provides design options for drilling a water bore. Where the assessments required under part 4 of this Code determine there is significant risk associated with drilling a water bore through hydrocarbons, then such a bore must be constructed according to the requirements in Part 2: Coal seam gas wells. A glossary for specific terms, abbreviations and acronyms used in this Code is provided in Appendix 1 – Glossary. Relevant industry standards, recommended practices, technical reports and industry experience should be considered in the design and implementation of the well construction process. This includes the use of standards and specifications developed by the American Petroleum Institute (API) and the International Organization for Standardization (ISO). A list of relevant industry standards and recommended practices is provided in Appendix 2 – Industry Standards. Code of Practice for the construction and abandonment of coal seam gas and petroleum wells, and associated bores in Queensland 3 2 Coal seam gas wells This Part applies to CSG wells and provides a way for petroleum tenure holders producing CSG, to comply with their obligations under Queensland’s petroleum legislation. 2.1 General description of coal seam gas drilling activities 2.1.1 Introduction There are generally two phases of CSG operations—exploration and production. Once a well is no longer required for CSG operations, it is abandoned. Abandoning wells involves: a) sealing of wells to prevent the intermixing of fluids and pressures between coal seams and aquifers b) preventing the escape of fluids to surface c) preventing injury and harm to people and the environment It also includes the process of decommissioning as described in legislation. CSG exploration drilling aimed to identify gas bearing reservoirs and sediments generally targets a large area, with typically one well per 30 to 60 km2 depending on the locality. If exploration indicates the potential for gas production, pilot wells may be drilled to confirm production performance and to further define reservoir properties. A pilot test is essentially a small scale production trial, with associated infrastructure. Production wells are typically spaced at some 600–1200 m or more, and may operate for many years or even for several decades. In addition to CSG wells, a range of activities associated with gas production means tenure holders require the following water bores. a) Water observation bores to enable impacts of CSG operations to be quantified. b) Water supply bores needed for undertaking their activities, and may be required for ‘make good’ purposes. c) Injection bores required for the injection of treated associated water or brine. d) Water bores converted from a CSG well for use by a landowner or other stakeholder. This Code provides standards and guidelines for construction operations for the range of wells and bores needed by CSG companies. Code of Practice for the construction and abandonment of coal seam gas and petroleum wells, and associated bores in Queensland 4 2.1.2 Well construction process The main steps involved in CSG well construction and abandoning for either exploration or production are: a) site identification and location b) site (or ‘lease’) access and preparation c) well design d) work program issued for well construction e) drilling f) logging and/or testing g) running and cementing casing h) well stimulation (if required) i) well completion j) CSG production k) well and bore abandoning (decommissioning) and site rehabilitation. During the normal course of any drilling program there will be various company and contractor personnel who will need to travel to the drill site. These people are required for: a) site checks and surveying b) earthworks (e.g. for access to site and to clear the drill pad area) c) drilling rigs and support vehicles d) water carting e) specialist testing service providers f) well site supervision and geological personnel g) cement and casing deliveries h) well intervention/well treatment equipment such as workover rigs i) support vehicles/services. 2.1.3 Site Identification and location All wells and water bores are first planned in a desktop process to identify potential or suitable sites within known constraints such as tenement boundaries, topographic constraints and environmental restrictions. Potential exploration well sites additionally have a desktop review undertaken to identify locations which may best define the geology of an area or project. In some cases this may be based on earlier seismic surveys. After the desktop assessment it is essential to then ‘ground-truth’ the proposed site, and at this stage it is critical that consultation with the relevant stakeholders takes place to choose the most appropriate site and consider all other constraints (e.g. access routes). In most cases there is reasonable flexibility in locating proposed wells to avoid particular sites. As a general rule there is more flexibility to move exploration wells than to move production wells. Well sites can usually be identified that present the least impact to the environment and existing land use. Petroleum companies are required by law to conduct various checks on any site where works are proposed. Code of Practice for the construction and abandonment of coal seam gas and petroleum wells, and associated bores in Queensland 5