Discrete Fracture Network Modelling in Triassic–Jurassic Carbonates of NW Lurestan, Zagros Fold-and-Thrust Belt, Iran

Abstract

In this study, discrete fracture network (DFN) modelling was performed for Triassic–Jurassic analogue reservoir units of the NW Lurestan region, Iran. The modelling was elaborated following a multi-scale statistical sampling of the fracture systems characterising the analysed succession. The multi-scale approach was performed at two different observation scales. At the macro-scale, a digital outcrop analysis was carried out by means of a digital line-drawing based on camera-acquired images, focussing on the distribution of major throughgoing fractures; at the meso-scale, the scan line method was applied to investigate the background fractures of the examined formations. The gathered data were statistically analysed in order to estimate the laws governing the statistical distribution of some key fracture set attributes, namely, spacing, aperture, and height. The collected dataset was used for the DFN modelling, allowing the evaluation of the relative connectivity of the fracture systems and, therefore, defining the architecture and the geometries within the fracture network. The performed fracture modelling, confirmed, once again, the crucial impact that large-scale throughgoing fractures have on the decompartmentalization of a reservoir and on the related fluid flow migration processes. The derived petrophysical properties distribution showed in the models, defined the Kurra Chine Fm. and, especially, the Sehkaniyan Fm. as good-quality reservoir units, whereas the Sarki Fm was considered a poor-quality reservoir unit.

Fractures in the Niagara Escarpment in Ontario, Canada: distribution, connectivity, and geohazard implications

“…Since a wide range of apertures were observed at the studied sites on the Niagara Escarpment (<1 mm to >40 mm wide), fluid-flow properties should also be considered to be highly variable. This study also supports previous works (Allan & Sun, 2003;Massaro et al 2018Massaro et al , 2019Giuffrida et al 2019Giuffrida et al , 2020 that suggest fracture aperture (Fig. 11) exerts a first-order control on fluid-flow properties.…”

“…However, the three-dimensional models produced (Fig. 9) illustrate rock compartmentalization by fractures similar to that described by Massaro et al (2018Massaro et al ( , 2019. The modelled block size can be compared with qualitative observations (Fig.…”

“…However, the majority of recorded joints are sub-vertical (87 % have dips >75°), and thus, in the context of the field observations, these simplifications are reasonable approximations of a complex real-world system. Massaro et al (2018Massaro et al ( , 2019 present similar DFN models for stratabound fractures in carbonate reservoirs for the purposes of estimating fracture connectivity, fracture-induced porosity and fluid-migration pathways. The results of the current study support their conclusion that fractures have a significant effect on fluidflow properties such that those of matrix porosity can effectively be ignored due to its low contribution to fluid flow when fractures are present (Massaro et al 2018(Massaro et al , 2019.…”

“…Fractures have a quantifiable orientation and aperture (Schultz, 2019) which can be documented for a range of purposes including the understanding of hydrocarbon reservoirs (Massaro et al 2018(Massaro et al , 2019Giuffrida et al 2019Giuffrida et al , 2020, structural inheritance and fluidflow properties (Gross & Engelder, 1991;Eyles & Scheidegger, 1995;Peace et al 2018;Samsu et al 2020). Semi-automated methods of fracture quantification have also been developed which have been shown to be useful in the acquisition of large data sets, in addition to limiting observer biases (Thiele et al 2017;Lee et al 2020;Palamakumbura et al 2020;Samsu et al 2020).…”

“…Manual fracture quantification was completed using both scanline and areal (also called 'window' (Watkins et al 2015)) surveys, both of which are standard methods used in similar studies (Gross & Engelder, 1991;Watkins et al 2015;Massaro et al 2018Massaro et al , 2019Andrews et al 2019;Giuffrida et al 2019Giuffrida et al , 2020. Surveys of both types were completed initially to capture vertical and horizontal variations in fracture distribution.…”