Monitoring and Control of Fugitive Methane from Unconventional Gas Operations

Monitoring and control of fugitive methane from unconventional gas operations The Environment Agency is the leading public body protecting and improving the environment in England and Wales. It’s our job to make sure that air, land and water are looked after by everyone in today’s society, so that tomorrow’s generations inherit a cleaner, healthier world. Our work includes tackling flooding and pollution incidents, reducing industry’s impacts on the environment, cleaning up rivers, coastal waters and contaminated land, and improving wildlife habitats. This report is the result of research commissioned and funded by the Environment Agency. Published by: Author(s): Environment Agency, Horizon House, Deanery Road, Mark Broomfield and Brian Donovan Bristol, BS1 5AH Dissemination Status: www.environment-agency.gov.uk Publicly available ISBN: 978-1-84911-278-9 Keywords: Methane, Fugitive, Fracturing, Shale, Unconventional © Environment Agency – August 2012 Research Contractor: All rights reserved. This document may be reproduced AEA with prior permission of the Environment Agency. Gemini Building Fermi Avenue The views and statements expressed in this report are Harwell those of the author alone. The views or statements Didcot expressed in this publication do not necessarily OX11 0QR represent the views of the Environment Agency and the Tel: 0870 190 6458 Environment Agency cannot accept any responsibility for such views or statements. Environment Agency’s Project Manager: Roger Timmis, Evidence Directorate Further copies of this report are available from our publications catalogue: http://publications.environment- Product code: SCHO0812BUWK-E-E agency.gov.uk or our National Customer Contact Centre: T: 08708 506506 E: [email protected]. ii Monitoring and control of fugitive methane from unconventional gas operations Evidence at the Environment Agency Evidence underpins the work of the Environment Agency. It provides an up-to-date understanding of the world about us, helps us to develop tools and techniques to monitor and manage our environment as efficiently and effectively as possible. It also helps us to understand how the environment is changing and to identify and respond to future challenges and pressures. The work of the Evidence Directorate is a key ingredient in the partnership between research, guidance and operations that enables the Environment Agency to protect and restore the environment by: Setting the agenda, by providing the evidence for our decisions; Maintaining scientific credibility, by ensuring that our programmes and projects are fit for purpose and executed according to international standards; Carrying out research, either by contracting it out to research organisations and consultancies or by doing it ourselves; Delivering information, advice, tools and techniques, by appropriate dissemination of products. Miranda Kavanagh Director of Evidence Monitoring and control of fugitive methane from unconventional gas operations iii Preamble This report has been produced to provide information to the Environment Agency on the methods available for monitoring and controlling fugitive methane emissions from onshore unconventional gas operations. The report focuses primarily on operations involving the hydraulic fracturing of shale to extract methane and includes some comparison with conventional gas operations. The report is based on a review of current practices, recent research and regulatory developments. It draws on published information including experience of hydraulic fracturing operations in North America. The report is designed to help the Environment Agency identify areas where it may need to acquire more detailed information and expertise, particularly if it is required to regulate future onshore unconventional gas operations in England and Wales. It is not designed to be a definitive account of all monitoring and control methods but to give an overview of the main techniques available and of the factors that should be considered when applying them for regulatory purposes. The report is not a statement of the Environment Agency’s position and it does not represent Environment Agency guidance on the matter. iv Monitoring and control of fugitive methane from unconventional gas operations Executive summary: scope and technical outline Study scope The Environment Agency is investigating the potential for fugitive methane to be released from unconventional gas operations to provide evidence in relation to the sustainability of unconventional gas. As part of this, the Environment Agency needs to assess what monitoring and controls may need to be applied to fugitive methane from unconventional operations as part of a regulatory regime to make unconventional gas extraction more sustainable. The present study was commissioned to contribute to this work programme with the following components: (i) Outline of unconventional gas extraction techniques; (ii) Outline of conventional extraction for comparison with the position for unconventional extraction; (iii) Survey of the methods available for monitoring methane from each process and position of fugitive release identified in (i); (iv) Survey of the methods available for controlling fugitive emissions of methane from each process and position identified in (i); (v) Case studies to illustrate how monitoring and control methods have been applied to fugitive emissions from unconventional and conventional operations; (vi) Summary of related issues that may arise during the regulation of fugitive emissions from unconventional operations; (vii) Conclusions and recommendations including the identification of best practice for the control of fugitive emissions and recommendations for a cost-effective strategic programme of monitoring and emission estimation. Technical outline Introduction Hydrocarbon extraction has taken place in Europe since the 19th century. The industry developed rapidly in the 1960s, following the discovery of oil and gas in the southern North Sea, and in the 1980s, following the discovery of reserves in the northern North Sea and Russia. The industry focused mainly on ‘conventional’ reserves. That is, oil and gas from high permeability rock formations, which could be more readily extracted. After decades of growth and stability, proved gas reserves in Europe are starting to decline. This change has coincided with the development and application of techniques in the United States for extraction of gas from reserves which were previously uneconomic or impractical in Europe. These resources comprise extensive shale gas reserves along with less extensive coalbed methane reserves. Gas shales are formations of organic-rich shale, a sedimentary rock formed from deposits of mud, silt, clay, and organic matter. The shales are relatively impermeable so that substantial quantities of natural gas are trapped within their pores. The low Monitoring and control of fugitive methane from unconventional gas operations v porosity of the rock means that the shale must be fractured to enable the extraction of natural gas. The situation in the UK has evolved during 2011–2012 with indications that UK recoverable reserves could potentially be of a similar scale to those of Poland and France. Commercial extraction of shale gas could commence in Poland in the next few years. At present, there is a temporary suspension of the use of hydraulic fracturing for shale gas extraction in the UK to allow time for considering its environmental implications. This is especially for any implications for seismicity. Industry forecasts of shale gas well drilling suggest that up to 200 wells per year could be drilled in the UK by 2020. Overview of hydraulic fracturing Hydraulic fracturing is the process by which a liquid under pressure causes a geological formation to crack open. It is used to extract gas from shale formations by drilling a vertical section of a well down and then drilling horizontally through the shale formation to maximise access to gas reserves. Once drilling is complete, the drill string is extracted and the well bore is lined with steel pipe. Cement is pumped around the outside of the pipe to lock it in place and provide a barrier to fluid transfer. Once the cement hardens, shaped charges are pushed down the pipe to the shale formation to perforate the pipework and cement layer at the required locations. Each horizontal well may be fractured at several stages. When perforations are present at the appropriate point, fracturing fluid at high pressure is pumped into the well. Fracturing fluid normally consists of water with a range of additives to facilitate the fracturing process including ‘proppants’. This is referred to as ‘slickwater’ fracturing. In some shale gas extraction sites in the US such as those with water sensitive components (for example, clay) and under saturated reservoirs, the fluid used for fracturing is thickened with gelling agents in order to increase its viscosity. The proppant is forced into the fractures by the pressured water and holds the fractures open once the water pressure is released. The sources of water used during hydraulic fracturing activities include surface water and groundwater These can be supplemented by recycled water from previous hydraulic fracturing. The quantities of water used depend on well characteristics (depth, horizontal distance) and the number of times each well is fractured. Vertical shale gas wells typically use approximately 2000 m3 of water while horizontal wells require approximately that amount

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