Project Greensand was initiated June 2021 after EUDP granted funding for validating the technical feasibility of the concept. The aim is to establish a full value chain for carbon capture storage in Denmark by 2025. The project focuses on offshore transportation and storage, and collaborates with partners, who focus on onshore capture, transportation and port bunkering.
All offshore transportation of CO2 will be handled by ship and injected via the offshore well head platform. The CO2 will be stored in depleted oil and gas sandstone reservoirs 1500m beneath the seabed and existing infrastructure will be repurposed from oil and gas production to CO2 injection, and hereby get a second life in the energy transition.
This field has more than 20 years of data collected from oil and gas production, which means that the behaviour of the reservoir and the subsurface structures are well known. All this data are used for qualifying the reservoir for CO2 storage.
The first phase will with the Nini West platform, which is part of the Siri area currently operated by INEOS Oil & Gas Denmark, with an expected storage capacity of 0.5 million tons CO2 per year by 2025, and a scalable capacity in the entire field of 3.5-4 million tonnes of CO2 per year.
The project started in early 2020, with its official kick-off in June 2020 after being granted funding from EUDP, and is divided into 4 phases:
Prove and validate how the Nini reservoir reacts to CO2. Numerical modelling of the storage site, including injectivity, max pressure and CO2 movements. Geomechanical and geochemical studies on core material and numerical evaluation of the sealing capacity.
Completion basis of design and laboratory assessments of required tubing size and steel quality to deliver the optimal injection rate. Cost and risk assessment of wells able to deliver the optimal injection rate and ensure long term mechanical integrity under conditions of cyclical pulsed injection
Based on the requirements determined by the reservoir and seal, and subsequently the wells, assessing if the required amount of CO2 can be injected via the existing infrastructure. Assess requirements for topside configuration and mature CO2 shipping concept.
Assessments of the probability of leakages: wells, seal, infrastructure. Monitoring programs to be put in place during injection and post-injection
In June EUDP granted funding for phase 1, the first technical validation of the storage concept. This study was kicked-off 26th of June and is conducted by INEOS Oil & Gas Denmark, Wintershall Dea, Maersk Drilling and GEUS.
Subsea reservoir was confirmed feasible for CO2 injection by independent certification body DNV GL to the endorsement of Danish authorities. With the “certificate of conformity – site feasibility”, DNV GL has confirmed that the Nini West reservoir is conceptually suitable for geological storage of CO2 and thereby suitable for further qualification according to the ISO 27914:2017 and DNVGL-SE-0473 standards. This confirms that Nini West is conceptually suitable for injection and long-term storage of 0.45 million tonnes CO2 per year per well over a period of 10 years.