Smart Pulses for Subsurface Engineering

Geological engineering encompasses a range of applications from resource extraction (hydrocarbons, geothermal heat and power, water) to waste disposal (Carbon capture and storage, wastewater disposal) and energy storage (compressed air, hydrogen). All of these technologies rely on pumps to move fluid into or out of boreholes. This prosperity partnership brings together teams that have previously worked on pumps for well stimulation with new team members involved in geomechanics and monitoring systems. Our previous work has shown that the pumps used in well stimulation are often used in very simple ways to deliver a known pressure to the top of the wellbore, leading to inefficient processes that produce a lot of noise and waste. Our partnership aims to re-engineer such systems through three linked research themes. Firstly there is evidence that pulses in pressure or dynamic variations in mean pressure could be more effective in achieving the aims of geological engineering processes. To understand the potential of pulsed pumping we need a deeper understanding of the material response to dynamic variation of the system that is being pumped: the rock mass and the borehole (casing and cement). Secondly we need to understand how to control delivery of precise pressure variations into the borehole and how to monitor these as they travel down the bore and into the rock mass. This includes the need to monitor rock mass response to develop fully 'closed loop' control systems. Finally we want to integrate the systems understanding of the pumps, the pumped system and the control systems. We will trial our new pulse propagation and monitoring system in the UK (at a site where well stimulation will not take place) and test the new monitoring system at an active well stimulation site in N. America. A series of eight linked PhD projects will explore aspects of the problems, and investigate the application of smart pumping to other sectors such as water distribution systems or transport of mining slurry. Our overall goal is to reduce the cost and increase the efficiency of geological engineering through smart pumping, thereby reducing the environmental and social impact of such technologies.

We have brought together a partnership of two industry and two university partners. The Weir Group and University of Strathclyde have a long history of collaboration on well stimulation pumps and other applications. The University of Edinburgh bring unique, world-leading geomechanical experimental capability to the partnership, and have previously collaborated with Strathclyde on carbon storage and compressed air energy storage. Silixa are young company specialising in optical fibres for sensing. Together this partnership will conduct the research that will underpin the development of smarter technologies in pumping and geological engineering.

A unique opportunity has risen to support an existing, strong partnership between the University of Strathclyde and the Weir Group with significant technical and scientific contribution from Silixa Ltd and the University of Edinburgh, to investigate the potential of smart pumping in subsurface engineering projects. Time dependent pressure loading could be key in optimum exploitation of subsurface energy resources but the understanding on the related physical processes and technological challenges prohibits its development to an engineering tool. The proposed research aims to provide detailed insights in the mechanical behaviour of rocks during fluid injection and highlight technological routes to make well stimulation a more efficient process, lower the recovery costs while maximizing environmental control. We will combine leading edge geomechanics technology with advanced monitoring, control and signal processing techniques for the optimisation of engineering design and risk control that could be integrated into other systems, e.g. in bioengineering. Weir are already engaged in a strategic collaboration with Strathclyde related to the engineering of high pressure pumps for well stimulation. Thus the companies have established a track record of collaborative product development that could serve as a template for future development of the technologies produced by this Prosperity Partnership project.

The beneficiaries of this study include:

1. Public Sector: This project will impact the nation's health and wealth; it will contribute to the economic competitiveness of the UK with the potential to adapt and apply the technology to optimize the process for gas storage, CO2 storage and deep geothermal exploitation. This is of major importance, specifically after the weak induced seismicity occurrence at Preese-Hall (Lancs, UK) in 2011. The reduction of the uncertainties involved in the injection of fluids at depth can positively influence the public attitude towards the use of shale gas/carbon capture as well as increase regulatory confidence, e.g. for safety case development and/or monitoring leakage in the case of CO2 storage.

2. Industry: The 'Smart pumping' proposition, as a world-leading technology, will contribute to the UK's successful progression to a low-carbon economy. The outcomes of this research will attract further funding in the form of R&D investment from international businesses and industries related to oil and gas, geothermal energy exploitation etc. The results will be used as foundation for the ability of the proposed methodology and technology to enhance the efficiency and performance of businesses, e.g., maximise the geothermal capacity of underground reservoirs by providing a better understanding of the sub-surface flow system and consequently contribute to environmental sustainability.

The facilities and knowledge gained during the project will put the UK at the cutting edge of predictive subsurface engineering analysis. The combination of machine intelligence and mechatronic control is an important driver for research and innovation, and supports our proposed integration of sensing, machine learning and analytical models in pump control systems - a deployment of technologies associated with Industry 4.0

3. Additional benefits: Material prepared throughout this project based on the knowledge gained about subsurface processes can be used at schools and local communities to contribute to engineering/geology/science related projects and enhance the learning process of the pupils and the engagement opportunities for local publics at future operational sites.