Characterisation of 3D Fracture Networks using Quantitative Outcrop Analogues Analysed with Lidar and Shallow Geophysics

Improving our understanding of flow of hydrocarbons and CO2 in fractured reservoirs requires detailed characterisation of three-dimensional fracture networks at seismic and sub-seismic scales. Terrestrial laser scanning (ground-based lidar) is a very rapid method to record the three-dimensional surface of outcrops, at centimetre resolution, with high spatial precision. Geological processing of the resultant lidar outcrop allows a virtual fracture network to be constructed. This can then be analysed semi-automatically in order to derive robust bulk fracture statistics for the outcrop. These typically include: fracture orientations; fracture size analysis; fracture spacing; fracture clustering; fracture connectivity; fracture orientations relative to fold geometries and dip of bedding in the host outcrop; variation of fracture geometry relative to stratigraphy; and spatial heterogeneity in fracture orientations. Lidar is essentially non-penetrative, however shallow geophysical methods, including Ground Penetrating Radar (GPR), can be combined with lidar data to derive fully three-dimensional models of the near sub-surface. To date we have analysed more than 25,000 fractures from over 45 sites globally, in a wide range of lithologies (including carbonates, sandstones, shales, mixed carbonate/clastic sequences, crystalline rocks) and tectonic settings (extensional, compression, strike-slip, and oblique).

Keywords: Virtual Outcrop; Terrestrial Laser Scanning; Reservoir Characterization; Ground Penetrating Radar