Fracture distribution along open folds in Southern Tunisia: Implications for naturally fractured reservoirs

Abstract

Fracture networks play a critical role in fluid flow within reservoirs, and it is therefore important to understand the interactions and influences these networks have. Our study focusses on the Southern Chotts-Jeffara basin which hosts reservoirs within the Triassic, Permian and Ordovician units containing significant hydrocarbon accumulations. Recent developments on the structural understanding of the basin have proven a regional shortening phase occurring between the Permian and Jurassic forming open folds and a distributed fracture network. Analysis of late Palaeozoic and Mesozoic outcrops within the basin identify several sets of fractures (150/80; 212/86) and compressional structural features which support this shortening hypothesis. We integrate fracture data from surface analogues and subsurface analysis of advanced seismic attributes and well data through structural linking to form a 2D hybrid fracture model of the reservoirs in the region. Through analytical aperture modelling and numerical simulation, we find that the fractures orientated 212° in combination with large-scale fractures contribute significantly to the fluid flow orientation and potential reservoir permeability. Our presented fracture workflow and framework provides an insight in network characterisation within naturally fractured reservoirs of Tunisia and how certain structures form fluid pathways influence flow and production. Supplementary material: https://doi.org/10.6084/m9.figshare.c.6904499