Jean Hsieh, Normand Begin, Maz Qayyum, Talisman Energy Inc., part of the Repsol Group
The Kurdamir-Topkhana field of Kurdistan is a carbonate oil and gas reservoir that was deposited in a passive margin ramp setting during the Oligocene. It is dominated by alternations of grainstone/boundstone/rudstone and packstone/wackestone beds. Reflux dolomitization early in the Miocene has noticeably increased, in places, both the porosity and connectivity of at least the Upper reservoir interval, as interpreted from seismic inversion data. The Lower reservoir interval was less affected by dolomitization and exhibits good porosity development within individual clinoforms, but much poorer connectivity between clinoforms. The entire reservoir interval is located within two anticlinal four-way closures formed above the roof thrust of an anti-formal stack developed within deeper Mesozoic carbonates; much of the observed fracture network is a result of this deformation. Modelling this complex reservoir presents significant challenges, not least because of the interdependency of many of the reservoir’s key characteristics.
The depositional and diagenetic history of the reservoir was determined through the study of several cores cut from the wells drilled in the field along with an understanding of the regional setting. A 3D seismic survey was inverted for acoustic impedance and the presence of gas-filled porosity can be imaged through the AI volume. Combining the understanding gleaned from the core and seismic data with the fracture data from borehole image logs, a detailed reservoir model was built. The strategy and conceptual models used for building this geostatistical model will be presented, along with our interim products and the lessons we have learned thus far on combining data of different scales.
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