Forecast of critical-stressed fractures on the basis of tectonophysics and geomechanical modeling on the example of the Riphean fractured carbonate reservoir in Eastern Siberia

UDK: 550.8.072

DOI: 10.24887/0028-2448-2017-12-24-27

Key words: fractured reservoir, Riphean deposits, the stress-strain state, geomechanical modeling, tectonophysical analysis, critical-stressed fracture

Authors: S.V. Zhigulskiy, A.V. Rotaru, S.V. Lukin, O.Yu. Kalinin (Gazpromneft NTC LLC, RF, Saint-Petersburg), D.O. Morozov, V.A. Gribanov (Gazpromneft-Razvitie LLС, RF, Saint-Petersburg)

In the current work the problem of natural fractures differentiation on the base of geomechanical and tectonophysical modelling and simulation is considered on the example of the naturally fractured carbonate reservoir of the East Siberia. It is established that the system of natural tectonic fractures is the main factor which controls productivity of the described reservoir. The fractures are characterized by high lateral discontinuity in terms of its kinematics and density even in the same tectonic blocks. As result wells productivities are highly volatile and poorly predictable. The main sources of information about fractures characteristics and distribution are seismic data and special geophysical methods, such as microimager and broadband acoustic logging. Initially, it was assumed that all natural fractures are permeable, but results of field geophysical surveys (PLT) and well production data revealed that productive zones do not correlate with the maximum fractured zones and these productive zones are distributed independently from the fractures trends. This fact led to the development of improved approach of fluidodynamic fracture assessment that considers static/morphological characteristics of the fracture, as well as their genesis, mechanism of loading, regional stress distribution and exact stress field around the fractures modified during the drilling process, exploration and wells production.

Such integration of the geological, geodynamical and geomechanical analyses allows to determine the state of stress in fractures and its contribution to fluid filtration possibility. This approach allows to improve the quality of the wells productivity forecast in case of the naturally fractured reservoir.

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