Minimising Risk in Fractured Reservoirs using Outcrop Analogues

Outcrop analogues play a vital role in the characterization of fractured reservoirs. Field-based studies are typically the most reliable way for fracture systems to be comprehensively quantified at sub-seismic scale, and allow the direct validation of fracture attributes derived from analysis of satellite imagery, aerial photos, core, and borehole image logs.

Using outcrop examples of carbonates, clastics and crystalline rocks we illustrate how a range of complementary data acquisition methods, including satellite analysis, digital photogrammetry, terrestrial lidar, and (most importantly) detailed fieldwork, can be used in combination to provide robust, quantitative multi-scale fracture characteristics for use as input for fracture network modelling. Key aims of this multi-scale approach are: (1) to constrain the maximum and minimum values for specific fracture characteristics, so that the viable ranges of input parameters for sub-surface modelling are minimised; (2) to quantify scaling relationships as precisely as possible so that key characteristics of the fracture system are not lost during upscaling; (3) to understand spatial variability across the reservoir; and (4) to analyse the sensitivity of the models to fluctuations in the input parameters.