An integrated workflow for multiscale fracture analysis in reservoir analog

摘要

The study of the naturally fractured reservoirs is very challenging with the main difficulty being how to model and predict the fracture networks at different scales extending from outcrops and shallow depth to the reservoir and basin depths. Advanced 3D seismic and well data are needed to characterize and model fractures, a process which is time consuming and requires great effort in terms of data collection and analysis. The study of the reservoir analog maybe an easier approach with more readily accessible data. The results can be used to characterize and model fractures at different scales using several available workflows. 3D model is used to understand the fracture distribution, connectivity, fractures kinematics, and emulate the fluid flow simulation. In this paper, an integrated workflow is presented to characterize and model the natural fractures using as case study in the Cambro-Ordovician reservoirs analog located at the Southern edge of the Mouydir basin, Saharan platform in Algeria. The workflow uses the temporal and spatial fracture distribution at the outcrops to predict their extension later at the subsurface. The analysis composed of two main steps. Firstly, the global fault map corresponding to the area of study, generated from the combination of curvature and illumination attributes, geological maps, satellite images, and digital elevation models, is built. The outcomes are the determination of fault sets, length distributions, correlation coefficients, power law coefficients, and fractal dimensions. Secondly, using the same input data and parameters, the fracture impact on the basement formations, in this case, different Cambro-Ordovician units, is analyzed. The proposed methodologies help to determine the major and minor fault sets at different scales to understand the fractography and typology of fractures affecting the Cambro-Ordovician units. The 3D deterministic fault model for each formation is built to illustrate the fractures distribution in space and time. The models superposition helps to determine the fracture origin, their relationship, kinematics, and illustrate the impact of the basement's faults on the sedimentary cover and the basin's structure.