Sparse Passive-Active Reservoir monitoring using Seismic, Electromagnetics, gravity, and surface deformation

Carbon dioxide (CO2) has been recognized as the main cause of global warming, with CO2 levels in the atmosphere rising as a result of human activity. If done on a large enough scale (Gt), Carbon Capture and Storage (CCS) can contribute significantly to reducing CO2 emissions by storing captured CO2 underground. One major challenge for large-scale CO2 storage operations is the cost associated with the geophysical monitoring during the operative phase and after the injection has ended. Monitoring is required in order to demonstrate safe storage and to assess conformance between the predicted and observed behavior of the injected CO2 as required by regulators (e.g., 20 years in Norway). The SPARSE project will contribute to facilitating large-scale (Gt) storage by establishing low-cost monitoring using of sparse geophysical data, collected from sea bottom or land nodes. These can serve as background monitoring systems to establish conformance with predicted behavior and to trigger target-oriented active seismic surveys when needed. This will reduce the number of conventional large scale 3D seismic surveys during the operational phase considerably, and it may remove the need for planned 3D seismic surveys in the post-injection phase altogether. The main requirements for such a monitoring system are: 1) that sufficient information can be extracted from the sparse data so that relevant changes in the subsurface can not only be detected but also quantified; 2) high repeatability; 3) low-cost installation, operation, and maintenance over decades. The SPARSE project will perform a comprehensive analysis of various different geophysical data types, analysis methods, implementation options, and associated cost over the lifetime of a CO2 storage site, to create a general sparse node-based monitoring “toolbox” and to find the optimum SPARSE monitoring configurations for given CO2 storage sites. During the first half a year, the Norwegian partners in SPARSE have established a consortium agreement between the project's 12 partners, set up a first version of a web page, arranged a kick-off, particpated and presented during ACT Knowledge Sharing workshop and US-Norway Bilateral Meeting I løpet av det første halvåret har de norske partnerne i SPARSE etablert en konsortieavtale mellom prosjektets 12 partnere, satt opp en første versjon av en hjemmeside, arrangert en kick-off, deltatt og presentert under ACT Knowledge Sharing Workshop og US Norway bilateral meeting. During a project workshop in November 2023, SINTEF presented the first results from work with testing methods for use of various types of passive seismics for monitoring. In addition, SINTEF presented the planning of a study of how geomechanical modelling can be used to improve sparse monitoring and which data source can be used.

One major challenge for large scale CO2 storage operations is the cost associated with the geophysical monitoring during the operative phase and after the injection has ended (e.g., 20 years in Norway) to demonstrate safe storage and to assess conformance between the predicted and observed behaviour of the injected CO2 as required by regulators. A possible solution such for low-cost monitoring is the use of sparse geophysical data, collected from sea bottom nodes. These can serve as background monitoring systems to establish conformance with predicted behaviour or trigger target-oriented active seismic surveys when needed. This will reduce the number of conventional large scale 3D seismic surveys during the operational phase considerably, and it may remove the need for planned 3D seismic surveys in the post-injection phase altogether. We envision the use of strategically distributed geophysical monitoring "nodes" that contain seismic and EM sources and receivers, as well as a gravimeters and surface deformation observations that can be deployed (semi-) permanently on the sea floor or on land. The seismic receivers may consist of conventional seismometers and fiber-optic cables around the node. The use of complementary data will enable the quantitative estimation of subsurface parameters (e.g., pressure and saturation), relevant for assessing conformance and containment around the node. We will develop a principle node design that can be adapted to the site specific requirements and monitoring target. The main R&D activities are: a) investigation of all potential data types or aspects of data that may be suited for the sparse node-based monitoring, and b) quantification of key parameters for conformance/containment monitoring from (multi-physics) sparse data c) practical implementation of a low-cost sparse system (technical, automatic conformance, practicality, cost).