Methodology for considering cavernous reservoir in geological model (on the example of the field in Timan-Pechora oil and gas bearing province)

UDK: 550.8.072

DOI: 10.24887/0028-2448-2025-5-84-86

Key words: carbonate reservoir, secondary porosity, caverns, data integration

Authors: I.I. Churochkin (ZN NTC LLC, RF, Moscow); Yu.M. Trushin (ZARUBEZHNEFT - Dobycha Kharyaga LLC, RF, Moscow); I.V. Matveev (Heriot-Watt Petroleum Learning Centre, Tomsk Polytechnic University, RF, Tomsk)

In terms of chemical properties, limestone is an unstable rock and is susceptible to dissolution by water. Secondary voids have complex unpredictable geometry, heterogeneity of distribution, variety of scales and can create a useful volume for hydrocarbon accumulation. The main object of study is the carbonate reservoir of object A of oil field X, located within the Timan-Pechora oil and gas bearing province. It was established that the Famen deposits can be divided into two main zones in terms of sedimentation conditions: the barrier zone in the south and the back barrier in the north. The back barrier is dominated by a matrix type of reservoir with no faulting, fracturing and karst. The model, which takes into account the porosity cut-off reservoir, does not correspond to historical data. To identify cavernous intervals, drilling data (drilling mud losses), formation microimager (FMI) and production liquid tool were analyzed. In the interwell space, karst (after upscaling karst curve to grid cells) is distributed by Sequential Indicator Simulation method within the barrier. Porosity in the model cells with karst is obtained by analyzing Porospect (FMI-based) and NMR (Nuclear Magnetic Resonance) results on core samples. The model that takes into account caverns shows better convergence with historical data.

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