Odfjell Technology, an integrated supplier of offshore drilling and well operations equipment, has successfully utilized its innovative rigless plug and abandonment (P&A) unit for a geothermal pilot project in Tromsø, Norway. This project marks a significant step forward in the development and testing of an underground heat storage concept, employing equipment and operational principles derived from the offshore oil and gas industry.
In collaboration with Xrig and Halliburton, Odfjell Technology played a crucial role in planning and executing this venture for Kvitebjørn Varme, the company responsible for operating the district heating facility in Tromsø. The primary objective of the project was to advance an underground heat storage concept pioneered by Ruden AS, which received the prestigious innovation prize at ONS in 2022.
The project aimed to create a network of subsurface fractures connecting a central injector well to surrounding production wells arranged in a circular pattern. All wells had been previously drilled to a depth of 300 meters. Odfjell Technology's rigless P&A unit was employed to deploy a hydraulic stimulation assembly, utilizing sand jetting and fracturing techniques to create fractures in the formation every five to seven meters between 270 and 70 meters below the surface.
Following the successful establishment of fractures, an injection test was conducted to confirm significant flow communication between the injector well and the various production wells. This ensured that optimal downhole conditions were achieved for further testing of Ruden AS' heat storage concept.
With the fracture system in place, Kvitebjørn Varme can now utilize the surplus heat generated by its plant during the summer months to warm water. The heated water is continuously circulated down the injector well, through the fracture network, and up through the production wells. Over time, the heat is transferred from the water to the surrounding rock formation. In winter, cold water is circulated through the same heated fracture system, allowing the stored heat to be transferred to the cold water. The production wells then generate hot water ready to be directly distributed into the district heating network.
Moreover, Odfjell Technology's rigless P&A unit can be employed for rigless slot recovery and P&A operations on fixed offshore platforms, resulting in reduced emissions due to saved rig time, decreased personnel requirements, and improved transport logistics.
The deployment of the rigless P&A unit can save up to one-third of the rig time typically required for new well slot recovery operations. It also has the potential to reduce the required rig time by half for permanent P&A campaigns, thanks to its efficient use of rig drilling towers and associated resources.
Elisabeth Haram, Executive Vice President Well Services at Odfjell Technology, expressed the company's commitment to playing a leading role in the energy transition, leveraging their 50 years of experience in the oil and gas industry. She emphasized the significance of the pilot geothermal project and highlighted how Odfjell Technology's technology and expertise can be applied across the energy spectrum.
Through collaboration and knowledge-sharing between industry leaders in the oil and gas sector and emerging partners in the energy industry, remarkable achievements like this geothermal project can be realized. Odfjell Technology plans to launch its full rigless P&A unit offering for offshore slot recovery and P&A operations in the next four to six months, eagerly anticipating opportunities to implement this technology on a global scale in partnership with customers and collaborators.
