Multi-scale modelling of fractures and stresses: from basins to well
In this study we perform finite element (FE) geomechanical simulation to quantify mechanical response in terms of loading, failure and growth of complex network of pre-existing faults and fractures. This can be done in much greater detail by starting from a pre-existing network than by modelling the inception of a new network. The characteristics of a pre-existing fracture-fault (F-F) network are best obtained from deterministic reservoir data, combined with outcrop analogue studies. Deterministic F-F network descriptions are used wherever feasible. If not, network characterisations in terms of shape, direction, spacing, height and length are used to describe the discontinuity surfaces.
Building on the results of the 1st stage, this proposal focuses on the volume surrounding the borehole.
We will start by refining the geological/fracture model; continue by investigating the mechanical response to changes in boundary conditions; and set the first steps to analysing the impact of fluid injection, by investigating the consequences of effective pressure reductions on existing fractures and faults, as well as on the generation of new discontinuities.
The aim of the proposal is to predict the mechanical response based on discrete surface network models that include intermediate-scale (101-103 m) fracture-fault networks. This intermediate scale bridges the gap between the induced small-scale fracturing around boreholes and the critical loading of faults at the largest length scales for seismic risk.