Microseismic monitoring for operators and regulators (MORE)

Microseismic events are very small earthquakes, which can be generated through anthropogenic influences on sub-surface geologic reservoirs. Even though the magnitude of these events is usually only equivalent in energy to that of breaking a pencil, these events provide a detailed description of how the rock is fracturing and where fluids may be flowing. There are number of application of monitoring microseismic events, including shale-gas stimulation (fracking), CO2 storage, waste-water disposal and geothermal engineering. Shale-gas in particular has been an economic game changer in the USA, but increasingly regulators are requiring microseismic monitoring of injection operations. The market for this technology is growing quickly - less than 5% of fracking operations are monitored in the USA, but it highly likely that all European fracking operations will be required to have microseismic monitoring.

Bristol University has been doing research in this area for the past 10 years and is ahead of the curve in technology, as the industry norm is to simply locate events. Event locations are useful, but are often not a good indicator of the efficacy in fluid stimulation - fracking often fails. To address this, we have developed a suite of software that characterises the seismic source, monitors fracture network development, and holds the potential to track fluid migration through the subsurface. This will identify untapped regions and guide subsequent treatments. A significant market advantage is our aim for automated real-time monitoring. This technology also plays an important environmental monitoring role, as it can be used to inform regulatory procedures that will limit potentially damaging operations in unfavourable environments (high pre-existing stress).

The proposed project will link a series of research-grade programmes into a commercial-grade software package. This will provide the software to implement a best-practice for monitoring induced-seismicity. We have good links with the industry and potential clients, and have expressions of interest from a larger seismic acquisition company looking to move into the microseismic monitoring, a SME with experience in borehole operations but not microseismic monitoring, and a mid-size company interested in monitoring baseline seismicity in regions of shale-gas exploration.

The proposed processing software package will be of use to range of stakeholders. This is rapidly growing area of technology and a number of SMEs are forming. Many have experience with borehole technology, but few have done any passive seismic monitoring. They often possess the hardware, but lack the software to process the data. They also lack the experience interpreting the data.

There are a few large seismic acquisition companies that currently dominate the market (see preliminary market survey in attachments). They are primarily located in North America. Bristol has a distinct advantage in that we have developed the next generation of techniques to better exploit seismic data. One component of our work has already led to the formation of a small company by a recent postdoctoral research assistant, which has already been taken over by one of the large USA-based companies (Haliburton). Bristol is looking to further exploit the techniques it has developed in a more integrated approach, where results from one technique provide the starting point for the next.

The final stake-holder is the regulatory sector. As Europe considers its role in shale-gas exploitation, CO2 capture and storage, and geothermal energy, any proposed operation will require baseline studies of seismicity and regional studies of induced seismicity during operation. There is a potential new market in environmental impact assessment for these operations. The UK has proposed a 'traffic-light' system for monitoring induced seismicity, but few companies do this sort of analysis in a rigorous way. Bristol has developed a best practice manual for such monitoring.

This project will help with the commercialisation of our product, as it will enable the upgrade of a suite of research-grade programme to a commercial-grade software package. Our code is written in a number of different programming languages including Fortran and Matlab. The aim is to have a coherent software package on a single platform, where outputs become inputs for the next step. Bristol has developed a number of techniques for using microseismic data to assess the impact of induced seismicity, including the efficacy of fracture stimulation. This is valuable information to operators and regulators and can save money in the long term. For example, the industry norm is to simply locate microseismic events. But often this does not provide important information about fluid ingress and permeability enhancement in the rock. Fracking often fails - reservoirs may be compartmentalised and subsequent treatments can be guided using our methods. In summary, our enhanced processing flow will save companies money, through increased efficiencies in stimulation and monitoring programmes.