Abstract We aim to demonstrate the use of high-resolution sedimentological data during the early phase of the exploration cycle. The data reviewed included more than 1300 m of log sections taken North of Erbil. This was combined with field mapping, a microfacies study and the acquisition of routine core analysis data from plugs to provide a more complete analysis. Subsurface data included lithological information from two wells and 2D seismic lines with a total length of 487 Km.
The study focussed on carbonate sequences including potential and known hydrocarbon reservoirs, notably the Qamchuqa-, the Shiranish-, the Khurmala- and the Pila Spi Formations. As a result a refined stratigraphic and depositional framework for the Lower Tertiary and Upper Mesozoic sequences has been established. The Cretaceous sequences analysed herein display a series of distinct lithofacies types ranging from shallow marine to deeper marine environments, which can be attributed to different main depositional complexes. The Paleogene sequences show a high diversity of lithotypes that relate to fluvial, fluvio-marine, mixed siliciclastic - carbonate shelf and inner platform depositional environments.
Outcrop samples from both Tertiary and Cretaceous dolomites inherit the highest porosities thus presumably best reservoir quality in the subsurface. However, the effect of fracturing cannot be assessed in detail from surface data alone.
A 3D facies model has proven useful in displaying the spatial relationship of the well and outcrop data. The display of facies probabilities improves the recognition of cyclicity within homogeneous dolomite sections. Possible extent and connectivity of geobodies could be assessed with the model.
The results have been compared with, and put into a regional context with data from literature and proprietary selected subsurface data. The outcrop data have been incorporated into a workflow that supported other G&G subsurface disciplines during the exploration phase.