NZS 2403:2015. New Zealand Standard. Code of practice for deep geothermal wells. Superseding NZS 2403:1991 NZS 2403:2015

Transcription

1 NZS 2403:2015 New Zealand Standard Code of practice for deep geothermal wells Superseding NZS 2403:1991 NZS 2403:2015

2 COMMITTEE REPRESENTATION This standard was prepared under the supervision of the P 2403 Committee the Standards Council established under the Standards Act The committee consisted of representatives of the following: Nominating Organisation Contact Energy Ltd GNS Science Institution of Professional Engineers New Zealand Local Government New Zealand MB Century Mighty River Power New Zealand Geothermal Association WorkSafe New Zealand Representative Ralph Winmill Greg Bignall Chris Taylor Bridget Robson Alastair Maxwell Shanon Garden Hagen Hole Donna Ellis ACKNOWLEDGEMENT Standards New Zealand gratefully acknowledges the contribution of time and expertise from all those involved in developing this standard, used by the sector as a code of practice. In particular, Standards New Zealand acknowledges the funding that WorkSafe New Zealand provided to support this revision; the preliminary draft with updates that the New Zealand Geothermal Association (NZGA) prepared for the committee to consider; and the detailed submissions received on an early draft from key organisations including: the Bay of Plenty Regional Council, Contact Energy, Jacobs New Zealand Limited, MB Century, Mighty River Power, NZGA, and Waikato Regional Council, as well as individual submitters including Paul Bixley, Richard Cottrell, Lindsay Fooks, and Jim Southon. Standards New Zealand also acknowledges the support provided by Mighty River Power and Contact Energy towards the cost of editing the final draft of this standard. Cover photographs: Top left, aerial view of MB Century Rig 32 at Wairakei well WK321, courtesy MB Century. Top right, production well RK26, Nga Awa Purua geothermal power station, courtesy Alan Ofsoski, Mighty River Power Co. Ltd. Bottom, MB Century Rig 32 at Wairakei well WK321, courtesy MB Century. COPYRIGHT The copyright of this document is the property of the Standards Council. No part of this document may be reproduced by photocopying or by any other means without the prior written permission of the Chief Executive of Standards New Zealand, unless the circumstances are covered by Part 3 of the Copyright Act Standards New Zealand will vigorously defend the copyright in this standard. Every person who breaches Standards New Zealand s copyright may be liable, under section 131(5) (a) of the Copyright Act 1994, to a fine not exceeding $10,000 for every infringing copy to which the offence relates, but not exceeding $150,000 for the same transaction, or to imprisonment for a term not exceeding 5 years. Those in breach under section 131(5) (b) of the Copyright Act 1994 may be liable to a fine not exceeding $150,000 or to imprisonment for a term not exceeding 5 years. If there has been a flagrant breach of copyright, Standards New Zealand may also seek additional damages from the infringing party, in addition to obtaining injunctive relief and an account of profits. Published by Standards New Zealand, the trading arm of the Standards Council, Private Bag 2439, Wellington Telephone: (04) ; Fax: (04) ; Website:

3 New Zealand Standard Code of practice for deep geothermal wells Superseding NZS 2403:1991 ISBN (Print) ISBN (PDF)

4 NOTES AMENDMENTS No. Date of issue Description Entered by, and date

5 CONTENTS Committee representation... IFC Acknowledgement... IFC Copyright... IFC Referenced documents... vi Latest revisions... viii Review of standards... viii Foreword... ix Outcome statement... ix Section 1 GENERAL Scope Variation from mandatory provisions Definitions Units of measurement Notation Abbreviations Interpretation Record keeping WELL DESIGN In this section Casing strings Well design process Subsurface conditions Maximum Design Pressure Pressure containment Casing setting depths Casing diameters Casing materials and performance properties Casing stress Permanent wellheads Review and modification of well design during drilling Well design records WELL SITES In this section Well site access Well site selection Well site design and construction Cellar Drainage and waste disposal Water supply...47 iii

6 3.8 Multi-well sites Site security and signage Well site records DRILLING EQUIPMENT, TOOLS, AND MATERIALS In this section Equipment Tools Consumable materials DRILLING AND WELL TESTING PRACTICES In this section Competence and supervision of personnel Drilling fluids and hydraulics Drill string practice Well control Running casing Cementing casing Lost circulation Directional drilling Fishing Well completion Well logging and testing Drilling records WELL OPERATION AND MAINTENANCE In this section Maintaining well integrity Well monitoring Wells in operation Workovers Suspended wells Well site maintenance Well operation and maintenance records WELL ABANDONMENT In this section Purpose and requirements for abandonment Well assessment prior to abandonment Abandonment operations Well abandonment records Appendix A Consolidation grouting (Informative) iv

7 Table 1 Variation of ambient pressure and boiling temperature for pure water with elevation The well design process, step by step Standard hydrostatic pressures and BPD temperatures for a column of pure water with no dissolved gas Effect of temperature on casing properties Minimum design factors Recommended pressure limits for threaded CHFs API/ANSI flange compatibility (non-exhaustive list) API specifications and recommended practice for rotary equipment Content of drilling records Content of daily drilling activity record...88 Figure 1 Naming conventions used for casing strings and liners Downhole and wellhead fluid conditions Example of minimum casing shoe depth selection method Example of casing forces calculation before cement set Casing stress dependence on temperature Typical permanent wellhead Wellhead working pressure de-rating for flanges and valves conforming to ANSI/ASME B16.5 and to API Spec 6A Typical drilling wellhead for use while drilling with water or mud (non-aerated)...58 A1 Typical consolidation grouting layout v

8 REFERENCED DOCUMENTS The following publications are either directly referenced in this code or else contain information that is relevant to its development and implementation. American standards ANSI/ASME B16.5:2013 Pipe flanges and flange fittings: NPS 1/2 through NPS 24 metric/inch standard ANSI/NACE MR 0175/ISO 15156:2009 Petroleum and natural gas industries Materials for use in H 2 S-containing environments in oil and gas production API Spec 4F:2013 API RP 5A3:2011 API RP 5C1 (R 2010) API TR 5C3:2008 API Spec 5CT:2011 API Spec 5DP:2009 API Spec 5L:2012 API Spec 6A:2013 API Spec 6D:2012 API Spec 7-1 (R 2012) API Spec 7-2:2010 API Spec 7F:2010 API RP 7G (R 2010) API Spec 7K:2010 API Spec 8A:2001 API RP 8B:2014 API Spec 8C:2014 API Spec 9A:2012 API RP 9B:2012 API Spec 13A:2010 API RP 13B-1:2009 Specification for drilling and well servicing structures Recommended practice on thread compounds for casing, tubing, line pipe and drill stem elements Recommended practice for care and use of casing and tubing Technical report on equations and calculations for casing, tubing, and line pipe used as casing or tubing; and performance properties tables for casing and tubing Specification for casing and tubing Specification for drill pipe Specification for line pipe Specification for wellhead and Christmas tree equipment Specification for pipeline valves Specification for rotary drill stem elements Specification for threading and gauging of rotary shouldered thread connections Specification for oil field chain and sprockets Recommended practice for drill stem design and operation limits Specification for drilling and well servicing equipment Specification for drilling and production hoisting equipment Inspections, maintenance, repair, and remanufacture of hoisting equipment Specification for drilling and production hoisting equipment (PSL 1 and PSL 2) Specification for wire rope Application, care, and use of wire rope for oil field service Specification for drilling fluid materials Recommended practice for field testing water-based drilling fluids vi

9 API RP 13I:2009 API Spec 15HR:2001 API Spec 16A:2004 API Spec 16RCD (R 2013) API RP 64:2001 (R 2012) API STD 53:2012 ASTM E (R 2009) Recommended practice for laboratory testing of drilling fluids Specification for high pressure fibreglass line pipe Specification for drill through equipment Drill through equipment-rotating control devices Diverter systems equipment and operations Blowout prevention equipment systems for drilling wells Standard practice for installation, inspection, and maintenance of valve body pressure relief methods for geothermal and other high-temperature liquid applications Other publications Department of Labour (now WorkSafe New Zealand). Health and safety guidelines for shallow geothermal wells. Wellington: Department of Labour, Eaton, B A. Fracture gradient prediction and its application in oilfield operations. Journal of Petroleum Technology, 246 (1969): Enform Canada. IRP Volume #3 In situ heavy oil operations. Calgary: Enform, Holliday, G H. Calculation of allowable maximum casing temperature to prevent tension failures in thermal wells. Paper presented at ASME conference, Tulsa, Parry, W T, Bellows, J C, Gallagher, J S et al. ASME international steam tables for industrial use. 2 nd ed. New York: American Society of Mechanical Engineers, New Zealand legislation Geothermal Energy Regulations 1961 Health and Safety in Employment Act 1992 Resource Management Act 1991 Related documents ANSI/ASME B31.1:2012 API Spec 10A:2010 API RP 10B-2:2013 API RP 49:2001 ISO/PAS 12835:2013 ISO 13679:2002 Power piping Specification of cements and materials for well cementing Recommended practice for testing well cements Recommended practice for safe drilling of wells containing hydrogen sulphide Qualification of casing connections for thermal wells Petroleum and natural gas industries Procedures for testing casing and tubing connections vii

10 LATEST REVISIONS The users of this code should ensure that their copies of referenced documents listed above are the latest revisions. Standards referenced in NZS 2403 will continue to evolve beyond its publication. Take care to ensure that standards more recently published remain contextually appropriate; if there is any doubt, use the version of the standard referenced. REVIEW OF STANDARDS Suggestions for improvement of this code are welcome. They should be sent to the Chief Executive, Standards New Zealand, Private Bag 2439, Wellington Telephone: (04) , Fax: (04) , Website: viii

11 FOREWORD This code sets out the standards of the New Zealand geothermal industry for design and work practices necessary to ensure the safe drilling and operation of wells that penetrate hot subsurface conditions, particularly in volcanic regions. This code revises the 1991 code cited in the Geothermal Energy Regulations It is primarily a best practice guide for the New Zealand geothermal industry, whether or not reference to the 2015 revised code continues in any amendments to the Geothermal Energy Regulations. The code reflects practices that have been proven in the geothermal industry since the 1950s. While largely based on the standards, equipment, and practices of the onshore petroleum drilling industry, it reflects the material difference of below-ground conditions in geothermal systems. The code therefore describes a design process with methods, procedures, formulae, and data inputs that have particular application to geothermal conditions. As well as proposing a design process for geothermal wells, the code provides guidance to operators, drilling contractors, service companies, regulators, and other stakeholders on the drilling works and subsequent well operation. The guidance includes preparing and managing the well site, drilling equipment, tools and materials, drilling techniques, and managing the well integrity. While the code is not a safety document or an environmental management framework, adherence to the code s best practice guidance will support both safety and sound environmental stewardship. The code also provides a basis for: (a) (b) Environmental permitting conditions; and Use as a contract performance standard or service specification. Finally, the practice of hydraulic fracturing, widespread in the oil and gas industry, is not a recognised practice generally employed in the geothermal industry in New Zealand. Consequently, this code does not address such practices. OUTCOME STATEMENT This code promotes best practice in the management of deep geothermal wells throughout their lifetime from drilling through to abandonment of wells. It provides guidance and encourages operators, drilling contractors, service companies, regulators, and other stakeholders to improve the overall management of wells, including safety and environmental management. ix

12 NOTES

13 New Zealand Standard Code of practice for deep geothermal wells 1 GENERAL 1.1 Scope Application of the code The good practices specified in this code may be applied to a range of circumstances. However, it is applicable specifically to geothermal wells that: (a) (b) Reach, or may reasonably be expected to reach, a depth exceeding 250 m and contain predominantly water or steam at temperatures exceeding the boiling point of water for the mean ambient conditions at the surface of the well site; or Reach, or may reasonably be expected to reach, a depth of between 150 m and 250 m, and that: (i) (ii) Contain steam or hot water that may reasonably be expected to exert a shutin pressure at the wellhead of 0.5 MPa or greater, or Have expected or actual downhole temperatures within 20 C of the boilingpoint-for-depth (BPD) temperature as measured from the local water level Inclusions The code covers the drilling, operation, repair, and abandonment of deep geothermal wells. It includes all subsurface work plus the wellhead up to the top of the master valve. The code also applies to continuous wireline coring, coiled tubing operations, or other non-typical methods for constructing and maintaining deep geothermal wells. NOTE (1) Extreme or unusual conditions sometimes create circumstances that are beyond the scope of this code. These may be conditions such as temperatures above the critical point (373 C) of water or the presence of highly corrosive fluids. (2) The boiling temperature of water reduces with increasing elevation. Dissolved solids and non-condensable gas also affect the boiling temperature of water. In the absence of better data, mean values can be interpolated from Table 1. (3) The Health and safety guidelines for shallow geothermal wells (Department of Labour 2005) covers requirements for shallow geothermal wells (less than 150 m or between 150 m 250 m with conditions that do not exceed the conditions stated in 1.1.1(b)). 1

14 Table 1 Variation of ambient pressure and boiling temperature for pure water with elevation Elevation Ambient Boiling pressure temperature (m) (kpa) ( C) Sea level Exclusions This code does not cover: (a) (b) (c) (d) Reservoir engineering, although changes in reservoir conditions (for example, because of exploitation) may need to be considered in the design of wells; Environmental management of drilling and well operation activities including control of surface run-off, disposal of drilling fluids, and noise. These will usually be covered by environmental consents and permits under which the work is undertaken; Equipment or operations downstream of the master valve or other components of the wellhead containing the geothermal fluids (as defined in ), except where they may affect the design or use of well components; or The design, construction, and maintenance of any thrust frame. 1.2 Variation from mandatory provisions Any variation from a mandatory provision of this code shall be based on sound data and engineering, or the use of alternative recognised standards. Any variations shall be adequately justified and documented. The documentation shall be permanently stored by the well owner and be available to regulatory authorities (see 5.13 and 6.3). The code does not preclude the adoption of alternative techniques based on either sound data and engineering, or the use of alternative recognised standards. 1.3 Definitions Focus on New Zealand geothermal industry practice The definitions in this code generally conform to international usage. But the code places prime emphasis on geothermal industry practice as applied in New Zealand. In particular, the various casing strings are defined as shown in Figure 1. 2

15 Code of practice for deep geothermal wells This is a free sample only. Purchase the full publication here: Or contact Standards New Zealand using one of the following methods. Freephone: (New Zealand) Phone: enquiries@standards.govt.nz