GEO ExPro

Solutions for Monitoring Gas

In the face of widespread fears in the public about potential pollution as a result of fracking, we take a look at standards and best practices for environmental monitoring of onshore hydrocarbon exploration and development.
This article appeared in Vol. 10, No. 6 - 2013

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Source: GGS

In the past few months, a great deal of publicity has been given to the issue of the production of shale gas. In North America, the increase in gas production from unconventional reservoirs has helped drive down prices, while in the UK the Department of Energy and Climate Change (DECC) has made an initial evaluation of a large potential shale gas resource across the North of England (Geo ExPro, Vol. 10, no. 4). The gas produced from unconventional sources is one of the least environmentally damaging fossil fuels known. Yet the production of shale gas is controversial, mainly because of perceived environmental effects from the main technology needed to release the resource – hydraulic fracturing of the reservoirs, or ‘fracking’.

Environmental Issues

Environmental monitoring requirements for shale gas in north-west England need to demonstrate no contamination at (1) subsurface fracking, (2) shallow aquifers, (3) surface locations. Source: GGS One of the fears of campaigners against the process is the release of gas or the chemicals used in fracking, either unintentionally or because of poor practice. This could be into the atmosphere or the ground water, possibly contaminating local water supplies. If the correct procedures are followed, in particular with the use of properly cemented casing strings and the protection of drill sites from accidental fluid release by containment, then it is very unlikely that the production of shale gas will lead to environmental damage. Many cases cited (notably in the USA) have, after investigation, pointed to pre-existing sources such as shallow biogenic gas being responsible for contamination.

But such is the pressure of public opinion (reinforced by the popular press) that it is becoming very difficult for other countries to follow the North American ‘shale gale’. In France there is a ban on fracking and in the UK, in spite of governmental support, the leading UK shale gas operator, Cuadrilla, has only managed to frack a single test shale gas well. Even Cuadrilla’s conventional operations are disrupted by protestors. There is no doubt that if shale gas exploration and production is to become commercial in Europe, it will be with strict regulation and the need to win the ‘hearts and minds’ of people potentially affected by the operations.

Independent Gas Monitoring

Enter Ground Gas Solutions Ltd., (GGS), a private company based in Manchester, UK. GGS was founded in 2009 by Simon Talbot and John Naylor, who had both previously worked in landfill monitoring and contaminated land regulation and investigation. They set their company up as an independent specialist gas monitoring service that could provide both regulatory requirements and advice to operators. Initially GGS did not work for the energy business but provided a wide range of specialist monitoring and risk assessment to, for example, residential and commercial building developers, landfill operators, local government authorities and even the operator of the Forth Road Bridge in Scotland. These services include other continuous monitoring techniques, such as groundwater and air quality monitoring and monitoring of greenhouse gas emissions and radon gas. In their previous work, Simon and John had realised that, with the industry practice as it was then, there were two key aspects of environmental monitoring which were not being executed rigorously. The first of these was the need to take baseline studies, in particular to demonstrate whether any environmental effects detected pre-dated an operation. The baseline had to be measured over a sufficiently long period to account for any significant environmental fluctuations. As an example of this, in one case a regular influx of brackish water in groundwater at a site was shown to be correlated with tidal variations.

Monitoring at one site showed no abnormal gasses but periodic influxes of saline water represented by increased conductivity (green line, bottom graph). This was correlated with tidal variations (blue line third graph down). Source: GGS Continuous Monitoring

Another problem with the monitoring processes was that sampling was done at periodic intervals by an individual visiting a site and taking measurements. This could only give ‘snap shots’ in time and even if done on a regular basis could miss highly variable and irregular natural fluctuations in gas concentration. So GGS decided to develop continuous monitoring methods in order to measure concentrations of the most important gasses used in environmental monitoring. These are methane, carbon dioxide, oxygen, carbon monoxide and hydrogen sulphide, together with total Volatile Organic Compounds (VOC). Atmospheric pressure and borehole temperature and pressure are also typically measured. These measurements are usually taken once per hour but can be up to every three minutes if required.

In order to differentiate itself in the field of environmental monitoring, GGS developed the GGS DataPack®, a unique report format that takes the continuous monitoring data and presents them in an easy to read graphical format. This provides regulators and other bodies with a clear and precise report to improve understanding of the ground-gas processes and risks at a particular site. This is now an industry standard for this type of presentation.


Developing Best Practices

Continuous monitoring and shallow borehole installation. Source: GGS In 2011, GGS started to work together with Cuadrilla Resources Ltd. in the UK to provide independent continuous gas monitoring services in their shale gas exploration and extraction programme. As has become abundantly clear with the public and press involvement, it is likely that the demonstration of no or As Low As Reasonably Practicable (ALARP) environmental impact of shale gas extraction will have to go beyond mere regulatory compliance in order to satisfy public opinion. It will be essential that an independent body is involved in any monitoring.

Monitoring will also have to differentiate between gas that may originate from deep reservoirs (thermogenic gas) or shallow biogenic gas that may come from peat or other non-reservoir sources. As Simon Talbot says, “If you have methane recorded in near-surface soils, it’s very important to take samples to fingerprint it with isotope analysis.” So GGS and other operators also take samples at sites and then use specialist laboratory analysis to characterise the natural geochemistry of the sites. In some of the cases where operators were accused of contamination in the US, this had not been done, so it was difficult to refute the claims.

GGS is working with Cuadrilla and other operators to develop industry best practices and standards for shale gas development. Cuadrilla also believes this will be essential in order to maintain a licence to operate in this controversial field. Cuadrilla former CEO Mark Miller says that GGS’ services “will allow us to collect background gas levels and compare them before, during and after operations. continuing with our open and transparent communications with the community, we will make this data available to the public”.


Pioneering Work

Unobtrusive borehole monitoring. Source: GGS As a result of its groundbreaking work on continuous ground-gas monitoring as applied specifically to shale gas development, GGS has also been requested to advise other onshore UK operators. It so happens that GGS’ Manchester headquarters is fairly and squarely in the centre of the Bowland Shale gas resource evaluated by the UK DECC (Geo ExPro, Vol. 10, no. 4). The company’s unique technology and pioneering work in the field give it the potential to become a leader in independent gas monitoring and risk assessment that will undoubtedly become a requirement in any future shale gas work in the UK and elsewhere.

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