Geophysics for an Energy Transition

Introduction

As the world is slowly transitioning to non-traditional forms of energy use and consumption there are a number of energy related projects that still require high level geophysical applications in Canada and around the world. In the last few years projects outside the traditional oil and gas space have still required advanced geophysical techniques to ensure project success and completion. In this article I review a number of subject areas including exploration and development for geothermal heat/power, lithium resources as well as Inland LNG and carbon capture and storage. The geophysical applications and techniques used for these projects are discussed as well as the challenges that exist bringing these energy sources to maturity.

Geothermal Energy

The production of heat and electricity from geothermal energy is an old concept and has been around since the turn of the century. There are many sources of geothermal energy and it takes on numerous forms such as dry and wet steam, hot dry rocks and high temperature fields. Recent newer technologies that have been piloted in Central Alberta include a closed loop system developed by Eavor Technologies Inc. of Calgary. Their project plans to generate heat and power between 100 and 180 degrees Celsius, lower temperatures that have been traditionally required and at much shallower depths. These industry advancements and the increasing demand for renewable energy sources have driven a requirement for geophysical technology and skills to be applied in this space.

There are transferable geophysical work flows from oil and gas to the geothermal industry. As the challenges of geothermal energy include accessing subsurface rock with accuracy for well bore direction and placement as well as mapping formation thicknesses and reservoir properties, typical oil and gas geophysical applications can be successfully employed here as well. For example, horizontal wells are now being used by some geothermal operators to penetrate the formations of interest in order to pump down injection fluids for heating in the subsurface. The ability to identify the formations, locate the correct depths and path of the horizontals can be augmented quite well by advanced seismic interpretation, mapping and depth conversion methods in a given basin.

The reservoir properties of interest may also expand to fault mapping and detection based on the source of geothermal energy that is being accessed. For example, Mount Meager in British Columbia is a potential geothermal project that has been mapped and identified using seismic as well as potential field information in an effort to produce geothermal energy from fractured volcanic rocks. In this project they combined passive seismic recordings with deep magnetic and electric field measurements to improve the image of the subsurface faults and their connection to a magma chamber source of heat (Grasby et al, 2020). As the challenge is to provide sufficient heat and/or electricity from complex subsurface conditions, geophysical information and analysis can lend to efficiencies in tapping into the best conduits for maximizing the transfer of energy to the surface.

Lithium Exploration

Lithium exploration and development has seen an increase in activity recently related to the rising demand for lithium to supply batteries for consumer electronics and for electric cars in the future. A large amount of the world’s lithium is currently extracted from brine reservoirs located beneath salt flats, called salars, which are mostly located in South America and China. The cost and processing time of the salar brines, along with the increasing demand for lithium, has prompted investigation into alternative sources which include those associated with existing oil fields or other sedimentary sourced brines.

For example, Standard Lithium Ltd. has just commenced an industrial scale demonstration plant for lithium extraction using oil field brines from the Smackover Formation in Arkansas (Standard Lithium Ltd., 2020). Long an oil field producer, the Smackover had been recognized early on as having one of the higher concentrations of lithium brines in the United States (Bradley et al, 2017). Likewise in Canada, E3 Metals Corporation is planning to extract and produce lithium from Leduc oil field brines in south-central Alberta. The proximity of these projects to North American markets has an appeal from a security of supply as well as a cost control perspective.

Using the knowledge of geologic formations as well as having nearby infrastructure from a robust oil and gas industry, this potential source of lithium capitalizes on oil production combined with and an advanced filtration technology to remove the lithium from the produced subsurface fluids.

Considerable amount of geoscience knowledge and database analysis is required to determine the volume of brine in a given area as well as advanced water analysis and geochemical work to determine concentrations of lithium in a given area. In addition, an understanding of the producing rock formation to determine viable well flow rates is essential. All of this information is required before a financial model can be put together to determine if lithium can be extracted in a profitable way for any new project or area.

Geophysical data can play an important role in this analysis, from determining the size of the area from which these brines are extracted to the mapping of a given formation in terms of its thickness, porosity and connectivity – all of which relate to the ultimate flow of a given well or wells. If there is a region of higher lithium concentration but not a lot of well control, this kind of information is very valuable from a lithium exploration approach. Historically in Western Canada, petroleum industry water samples didn’t typically test for lithium concentrations so additional geoscience approaches and methods are required to high grade areas of economic interest. The higher the lithium concentration in a brine, the more likely it is to develop into a viable project.

Inland LNG

While LNG has been forefront in the Canadian energy news as a viable technology to export Canadian natural gas to overseas markets the development of Inland LNG has been growing quickly around the globe. The inland technology is a smaller scale version of the mega tidewater projects that have been built globally. The rapid growth of this portable, scalable technology has been based on an energy market transition to develop a clean fuels business around the world, including Canada. Natural gas is being sought after to replace coal, fuel oil and diesel as well as a supplement to renewable energy. In Canada government regulatory standards and carbon tax initiatives are encouraging the transition to cleaner fuels. Tourmaline Oil Corporation, for example, recently announced they will be displacing a number of their diesel fuel rigs with natural gas for an annual emissions saving of 9,500 metric tonnes of CO₂ equivalent per year (Tourmaline Oil Corp., 2020).

LNG, which stands for Liquefied Natural Gas, is composed almost entirely of methane. LNG is produced by removing any impurities in the natural gas stream and refrigerating the gas to convert it to a liquid. The inland facilities rely of being close to the supply of the natural gas and the LNG is then transported to the end users via portable tankers.

In parts of the world where natural gas is currently undiscovered or in short supply geophysical technology and advanced interpretation techniques are beneficial to help explore or exploit the resources in the area. Inland LNG is also a technology well suited to remote areas where traditional large scale gas pipelines and infrastructure have not been viable (Ross, 2019)

The mapping and geophysical imaging techniques may be similar technologies deployed for oil and gas in other parts of the world, but as the inland facilities are smaller, gas producing rates, pressures and pool sizes don’t need to be as large nor the formations as deep in the subsurface to provide the local energy market in this fashion. This can also mean that areas and reservoirs that were traditionally by-passed by previous oil and gas exploration and development may provide economic and viable sources for natural gas supply to Inland LNG facilities and networks.

There are benefits to a cleaner fuel supply from an environmental point of view worldwide, but there is also an economical advantage to be able to supply parts of the world with cleaner and less expensive alternatives to diesel fuel for trucking, for example. Many parts of the world have limited supplies of natural gas currently to replace their diesel trucks with LNG fuel. With our current tool box of geophysical imaging technologies we are well suited to finding and exploiting additional natural gas resources and reserves around the world to meet this demand. Imaging shallower targets, for example, may require revised seismic processing and acquisition parameters keyed into these targets. New or shallower geologic formations may require a different understanding of hydrocarbon source paths, permeability models, environment of deposition mapping and so forth. These are all skillsets well developed for mainstream oil and gas and are suited to repurpose for the development of Inland LNG around the globe.

Carbon Capture and Storage (CCS)

As Canada has an abundant supply of coal, natural gas, and oil reserves, the industry has explored ways to reduce the environmental impact of fossil fuel combustion. One way of reducing this impact is carbon capture and storage (CCS). CCS involves capturing CO₂ emissions from local sources and storing them below the surface in suitable subsurface rock formations. The removal of CO₂ from emissions is achieved using CO₂ capture processes. These processes, such as pre-combustion, post-combustion, and oxy-fuel combustion, produce a highly concentrated CO₂ stream that is, after compression, ready for transport and storage. Once a storage opportunity has been identified there are issues surrounding the amount of CO₂ injection, how this will be monitored and measured as well as storage integrity and capacity estimation. One example of a Canadian CCS project is Shell Canada’s Quest project. It was developed as one of the world’s first commercial CCS projects to handle CO₂ emissions from the Canadian oil sands and began operations in 2015. Since its start-up it has captured and stored five million tonnes of CO₂ (Shell Canada, 2020).

The variation and complexity of storage options demonstrates the need for a good understanding of geoscience principles including the application of geophysical technologies. Seismic can be used to identify a viable storage site, image its size and extent and provide estimates for the CO₂ storage capacity in the subsurface. Often determining if the project is sustainable and viable from an economic point of view is based on the rates of CO₂ injection. This requires a more detailed understanding of the reservoir, porosity, permeability and fracture network, if there is one.

Geophysical mapping techniques such as advanced attribute analysis, seismic inversion and fracture detection can lend to mapping the storage container and capacity for injection as well as containment. Quite often, the geophysical data is integrated with the geological and engineering reservoir parameters into a 3D static modelling software to assess the storage concept in three dimensions. This is very useful in terms of validating a project’s size and operational viability. Usually this can be tested dynamically, as a final phase, to ensure injection volumes and rates of CO₂ can be sustained and contained with integrity over the project lifetime.

The containment issue is important as the storage of CO₂ has to meet strict environmental standards, particularly in Canadian projects. Containment can mean a further understanding of the top seal in the reservoir, understanding fault geometries and connectivity’s as well as their influence on the potential fracturing of the reservoir. Integrating this with injection rates and the effects on reservoir pressure are important operational issues as well as potential issues to offsetting oil and gas producers. Given the size and scope of these CCS projects it is becoming increasingly important to use geophysical data and the advanced interpretative tools to ensure the success and viability of a given project.