Example of applied outcrop analysis and its significance as an analogue for surrounding giant gas-fields; Case study of Kuh-e-Surmeh region, southwestern Iran

Abstract

Outcrops provide crucial information that can be used for the improvement of subsurface geological modeling. The present work provides a great example of such an application from a study on two well-known carbonate reservoirs uniquely exposed in the Kuh-e-Surmeh region, south-west Iran. Surface geology data were collected through extensive field study while the equivalent subsurface geology was reviewed based on bore reports available from the nearby giant gas-fields. Moreover, Schmidt hammer data were collected to investigate the variation in outcrop's uniaxial strength and detailed fracture analysis was carried out using Unmanned Aerial Vehicle (UAV) photography and direct field observations in selected stations. At the end, dolomite and limestone were identified as the dominant lithology of outcrops, greater apparent fracture intensity values were estimated for Kangan formation (P21=0.46) and the base of upper Dalan formation (P21=0.48). Moreover, fracture density (P20) was shown to be directly related to the formation uniaxial strength and the height of fractures was revealed to be inversely proportional to the thickness of sublayers. At the end, the collected surface and subsurface data were found to be in a general good agreement in terms of the stratigraphic location of fractured zones and mineralogy data, specifically, for the case of upper Dalan formation.