Final Report December 2024

Abstract

The geomechanical response to CO2 injection is one of the key uncertainties in assessing containment risk for proposed storage sites. The SHARP project introduces a geomechanical readiness level (GRL) to help evaluate the need for geomechanical data collection and modelling within a project. Key developments for the project include to: develop basin-scale geomechanical models that incorporate tectonic and deglaciation effects, and use newly developed constitutive models of rock/sediment deformation (WP1); improve knowledge of the present-day stress field in the North Sea from integrated earthquake catalogues and a comprehensive database of earthquake focal mechanisms (WP2); quantify rock strain and identify failure attributes suitable for monitoring and risk assessment using experimental data (WP3); develop more intelligent methods for in situ monitoring of rock strain and failure, and fluid pressure and movement (WP4); quantify containment risk using geomechanical models and observations from the field and laboratory (WP5); communicate technology development on containment risk to industry and regulators (WP6). SHARP project results include regional and site-specific data, models from case studies, updated workflows and methodologies and recommendations: • Updated North Sea bulletin with the most homogeneous representation of North Sea seismicity available to date. • Updated borehole stress database with new supplements to the World Stress Map 2016 database and improving in-situ stress characterization from seismic analysis. • Evaluation of regional stress drivers including ridge push, burial and exhumation, glaciation and stress decoupling due to weak layers using comprehensive analysis of regional stress data and novel correlation methods based on mineralogy. • New site-specific rock mechanical data on samples from Northern Lights Eos well, Aramis site, Lisa Structure, Bunter sandstone analogue and field case in India. • Stress estimates for CO2 storage using seismic anisotropy and shear wave splitting • Method development and demonstration for uncertainty quantification, failure probability, probabilistic seismic hazard assessment and quantitative risk assessment applying new data • Demonstration of pre-cursors for failure in velocity data at laboratory scale • Outlining and discussing the potential for fibre optic monitoring for detection of seismicity and subsurface pressure changes and deformation. • Stable seismic event analysis, localisation, estimates of stress orientations and discrimination of natural and induced seismicity requires better offshore seismic resolution with near-source observations Selected case studies in the North Sea and India have been matured during the project period: the Northern Lights CO2 storage project in the Horda Platform area (N); emerging storage prospects in the Greater Bunter Sandstone area, which encompass the Endurance site (UK); the Lisa structure (DK). The North Sea projects have benefited from transferring knowledge from pioneering and more mature work in the Horda Platform area. Furthermore, new geomechanical data has been collected and evaluated for well-characterised offshore depleted oil and gas fields, like Aramis (NL) and Nini (DK), accelerating their transformation into viable and safe CO2 storage sites. All the sites in the North Sea have benefited from the regional studies and matured their geomechanical readiness level (GRL) during the SHARP project period, whereas India has started initial screening for identification and characterization of potential storage sites.