TRANSGEO is a regional development project that aims to explore the potential for producing geothermal energy from abandoned oil and gas wells in central Europe. Supported by 11 partner organizations and 10 associated partners in 5 countries, TRANSGEO will develop a transnational strategy and action plan to address this technical and economic opportunity. The project partners will start by identifying and characterizing thousands of abandoned wells in the North German Basin, the South German Molasse Basin, the Vienna Basin, and the Pannonian Basin. A web-based well selection tool will then be developed to assess the wells’ suitability for a variety of thermal storage and energy production technologies. These activities will be supplemented by modelling studies at selected sites, to inform the assessment tool and validate procedures that will be developed for each reuse technology. Next, we will match well reuse potential with local energy demand and heating networks to highlight redevelopment priorities, with a focus on wells that could support rural communities and industries in the energy transition. Finally, the partnership will propose a legal policy and incentive framework to facilitate and expand reuse of abandoned wells for geothermal energy production and storage across the region.

TRANSGEO is co-funded by the European Commission’s Interreg CENTRAL EUROPE programme.

Worldwide, hydrocarbon wells are being abandoned. At the same time, energy demand is rising and most countries are struggling to meet their carbon reduction targets. Furthermore, in Nordic countries like Canada, heating buildings and transporting fresh food over long-distances both contribute significantly to CO2 emissions. Could inactive hydrocarbon wells be re-purposed to produce renewable heat for buildings and greenhouses in winter ?

This case study evaluates the potential for repurposing a 1048 m deep inactive gas well into a deep borehole heat exchanger (DBHE) or a well used in a geothermal doublet to heat an 8.1-ha bell pepper greenhouse in the St. Lawrence Lowlands (Eastern Canada). This region has a low geothermal gradient (~23°C km^-1), but contains a ~1 km deep permeable unit. 3D numerical models were built using the FEFLOW software to simulate heat transfer and groundwater flow generated by these systems. Additionally, Python functions were developed to estimate heat and pressure losses, as well as simulate the dynamic operation of heat pumps, modify injection temperature and flow rate in the models as required, and calculate the systems’ electricity consumption.

Preliminary results indicate that the doublet and associated heat pumps would meet the entire heat demand, provided the good permeability value is confirmed. However, the DBHE system would supply only 68% of heat demand, but would also produce 34% of the cooling demand in summer and presents fewer risks associated with uncertain properties, geochemistry and gas emissions. Cost of both systems are currently being estimated for further comparison.

In this paper, we present an overview of the development of the first commercial geothermal system leveraging horizontal drilling and multi-stage stimulation. The project is located near an existing geothermal power plant in Northern Nevada.

The target zone for the development was a low permeable Mesozoic metasedimentary formation at a temperature of approx. 190 °C. One vertical monitoring well and two approx.1000 m long horizontal wells were drilled into the reservoir. The horizontal wells featured a cemented 7" production casing. The well design needed to accommodate multiple drilling hazards in the shallower sections as well as all complex stimulation and production loads.

The stimulation treatment was designed to create a large fracture surface area between the two lateral wells by maximizing fracture initiation points through a combination of multi-stage and multi-cluster limited entry stimulation techniques. Proppant was placed in the fractures to increase conductivity.

This paper will review planning, drilling, stimulation, and well test operations. Furthermore, key learnings and their applicability in other geographies and geologies will be discussed.

Seit Jahren befinden sich die betrieblichen Anforderungen im Zusammenhang mit Sicherstellung der Integrität der technischen Einrichtungen in den Bereichen E&P und Geothermieanlagen in einem stetigen Wandel. Gründe hierfür sind vielschichtig: steigende Betriebs- und Servicekosten, Ergänzungen behördlicher Auflagen und sich verändernde Förderbedingungen.

Im Bereich der Geothermie bestehen ähnliche Notwendigkeiten, da das für den Betrieb der Anlagen erforderliche technische Equipment den Komponenten aus dem E&P-Bereich ist und auch zum Schutz von Menschen und Umwelt Sicherheitsstandards abverlangt werden.

Die Vielzahl und ständigen Ergänzungen der Vorschriften bringt die Anlagenbetreiber zwangsläufig unter Zugzwang Lösungen zu finden, die Kosten für vorgeschriebene Wartungen einschließlich der Integritätsmaßnahmen an den Produktionsanlagen nicht in ein betriebswirtschaftliches Missverhältnis zum operativen Betrieb laufen zu lassen und somit zwangsläufig einen "Cost-cut“ zu erzeugen.

In dieser Präsentation sollen aktuellen Stillstands- und Außerbetriebnahmeprobleme zur Sicherstellung der WI an Bohrungen aufgezeigt werden. Bereich des WIMS wird erläutert und innovative Lösungen und Technologien zur Fehlersuche, -bestimmung und -behebung aufgezeigt.

Besonderes Augenmerk wird auf in jüngster Zeit zu beobachtenden Tendenzen der „Thinking outside of the box“ Strategien bei der Umsetzung der Herangehensweise an Problemlösungen gelegt. Technisches Know-how, welches ursprünglich für völlig andere Anwenderapplikationen entwickelt und erfolgreich eingesetzt wurde, kann auch allein oder in Kombination mit bereits vorhandenen Serviceoptionen im Bereich der Medienförderung über Tiefbohrungen zur Steigerung Anlagenintegrität genutzt werden.

Mehrere praktische Fallstudien haben gezeigt, dass durch den Einsatz dieser Herangehensweise eine deutliche Steigerung der Effizienz während des Betriebes bei gleichzeitiger Steigerung WI gegenüber technischen Risiken und der Umwelt sowie deutliche Kosteneinsparungen bei Service- und Aufwältigungsarbeiten erreicht werden können

This paper will highlight how one country, Scotland, is using its wealth of experience from the oil and gas sector to develop a new, but experienced, supply chain of companies to help drive new geothermal projects.

The Scottish offshore oil sector was characterised by innovation and engineering developments in harsh conditions. Now Scotland is leading a transition away from oil. We talk about a Just Transition, ensuring workers, companies and social and economic structures are not left behind. The skills and experience from the oil sector are transferable and valuable across new renewable energy industries, especially so in the geothermal field.

The paper highlights Scottish companies, with experience of drilling deep oil wells, that are now using that experience to cover many aspects of drilling 5km deep in Northern European geothermal projects, and also the role of the new National Geothermal Innovation Centre, a central hub for geothermal technology challenges both in Scotland and globally.

With both public support and private company buy in, the future for the Scottish Geothermal sector appears rosy. The focused effort to use the expertise and experience of its previous industries in a Just Transition is helping Scotland develop a supply chain of geothermal focused companies that see innovation, engineering excellence and environmental responsibility as a long established and fundamental part of the business. This offers advice, examples and expertise for German geothermal projects and can only be good news for the German and wider European geothermal sector.