Karachaganak, an isolated carbonate platform, is a gas-condensate-oil field located in the Pri-Caspian Basin. Production, started in 1985, is now focused on liquid recovery. In 2003 gas injection was implemented.

Despite the huge amount of geological data of different vintages, there is not yet a general consensus about the conceptual geological model. This fact is due to poor quality data and lack of reliable analogues. In particular the integration of geological data with 3D Seismic data, affected by the presence of salt-domes, is ambiguous.

The main critical issue is represented by the presence of an enhanced permeability affecting about 15% of the reservoir. An adequate description of this event, at present randomly distributed in the reservoir models, would represent an effective tool to optimize both new wells location and further developments.

The issue has been tackled in a pragmatic way cross-checking dynamic and geological data vs. several geological scenarios and thus testing their reliability. Using effective data-base tools, production and Well-Test data of 169 wells have been cross-checked with geological and petrophysical data at different scale of observations ranging between micro-permeameter measurements to Seismic Stratigraphic Units. Well-Test permeability, based on PLT’s contributions, was a key factor.

This analysis has allowed the endorsement of a model resulting very effective in differentiating the reservoir into petrophysically homogeneous Depositional Regions. The distribution of enhanced permeability resulted linked to the geological evolution, and particularly to the bank internal geometry, consisting of an aggradational phase bioherm-dominated, and a progradation phase characterised by clinoform depositional bodies.

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