Fracture network analysis of Jebel Madar (North Oman): new perspectives from very-high resolution Digital Outcrop Modelling

Jebel Madar is located in the Adam Foothills of North Oman. It has been interpreted as a salt-cored, faulted anticline caused by the movement of the Precambrian-Cambrian Ara salt Fm, during the orogeny of the Oman mountains. The out-cropping Shuaiba and Natih carbonate rocks are reservoirs analogues for numerous Omani hydrocarbon fields. The maximum depth of burial is interpreted to be similar to those observed in the sub-surface fields. Therefore, Jebel Madar is considered a perfect structural analogue of fracture and fault dominated reservoirs above a salt dome in sub-surface conditions. Previous fracture studies focused mostly on the peripheral parts of Jebel Madar (i.e., Natih Fm.). Thus, fracture patterns are described as being radial, independent from regional fault and fracture pattern, and therefore, hypothesized as controlled by salt doming.

Recently, we conducted a high-resolution drone photogrammetry survey focused on the central parts of the jebel, in order (1) to update and detail fault and fracture patterns; (2) to refine our understanding of its structural evolution model; (3) to serve as a foundation for virtual reality field trips and courses.

The dataset comprises ~ 37,000 drone photographs with a total aerial coverage of ~ 6 km² and a resolution between 3cm and 1 mm. This enables us to develop 44 Digital Outcrop Models (DOMs), with a total of ~ 10.2 billion points. This unique database allows us to quantify the fault and fracture networks of Jebel Madar, in terms of orientation, intensity and 3D arrangement. The DOMs also provide a unique opportunity to map, analyze and interpret fractures and faults that are not accessible by field geology, but only accessible by drone.

This contribution shows early results of the high-resolution Digital Outcrop Model-based fault and fracture analysis. We will illustrate the impact of mechanical stratigraphy on fracture distributions in 3D and re-evaluate the impact of regional tectonics on the structural rise of the dome.