Deliverable 1.1b Stress Drivers and Outline of Proposed Numerical Modelling Campaign
Research report
Published version

View/ Open
Date
2022-10Metadata
Show full item recordCollections
- NGI report [224]
Abstract
A current synthesis of the understanding of the in situ stress state is presented for the Horda Platform, Endurance Structure and Greater Bunter sandstone area, Aramis, Lisa and Nini structures in the North Sea (section 2). Highlighted stress generation mechanisms include ridge push, sediment and progradational loading, continental margins, glacioeustatic adjustments, and uplift/erosion. Assessment of the relative importance of these mechanisms throughout the areas is displayed as a stress matrix (Table 2-1); which provides invaluable information for site characterisation. Following the assessment of relevant stress drivers, a proposal of relevant geomechanical models to encapsulate significant processes present at each site is presented in sections 3 and 4. Empirical laws and relevant rheological properties implemented in models are highlighted in section 3.2. Recent modifications to relevant rheologies are also considered, new for WP1. Three types of geomechanical forward models are proposed (A-C) (section 4) that explore stress in various dimensions and scales. Type A models explore the influence of mineralogy, stress translations at depth and loading/unloading processes in a uniaxial 1D model. Results can be calibrated to well data and provide estimates of minimum subsurface stress. Type B models involve regional 2D/3D modelling and provide a means for an investigation into the relative contributions of in situ stress along large-scale transects, as well as the analysis of spatial trends in the magnitude and orientations of stresses. Modelled stress outputs can also be compared to focal mechanism data to give insights as to the degree of coupling between thick and thin-skinned deformation. Type C (2D/3D) models explore site-specific contributions to stress variability from structures such as evaporite diapirs, stress field coupling and glacioeustatic responses of subsurface structures. Model results will provide insights into the evolution, in-situ state and potential risks linked to CO2 injection into the areas of interest. This provides invaluable information for other work packages as well as a general contribution to advancing CCS site characterisation.
Series
NGI-rapport;20210518-D1-1BSHARP Storage;Deliverable 1.1b