The Karatau Mountains Jurassic Succession (Western Kazakhstan): An Outcrop Analogue for the Kalamkas Offshore Reservoir System (North Caspian Sea)

摘要

Outcrop analogues represent a strong help in the building of geological models for exploration and reservoir studies. In particular, whenever the detail of the available subsurface dataset is inadequate to describe the complexity of the geological setting, the study of a proper outcrop analogue may help reducing considerably the structural and reservoir architecture uncertainties. In September 2002, the Kalamkas 1 exploration well successfully tested a multi-layer sandstone reservoir in the north Caspian Sea, the reservoir being composed of a thick succession of interbedded sands and shales, Jurassic in age. Given the encouraging results of the exploration well, and in order to get a better understanding of stratigraphic succession in the offshore license area, Agip KCO (then JV Operator), with the collaboration of the Satpaev Institute of Geological Sciences of Almaty and the Sedimentological Department of Eni E&P Division, decided to carry out a geological field survey in the Karatau Mountain Belt. The Jurassic paralic exposures have been studied with the aim of building the geological model for the time equivalent Kalamkas reservoir. Stratigraphic, sedimentologic and structural data have been collected in order to frame the Karatau and the Kalamkas offshore strata within a common regional geological framework. At the same time, a detailed field work approach, integrated with high resolution satellite imagery and LIDAR data acquisition, allowed to obtain a semi- quantitative reservoir-scale model to be used for driving an early Kalamkas offshore reservoir modelling. This paper illustrates the summary of the field work done in 2004 and 2005 and the application of the results to an early phase of the Kalamkas project workflow.