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Mapping of Complex Fractured-cavernous Overpressure Zones in the Sedimentary Cover of the Northeastern Part of the Angara-lena Step by Geophysical DataNormal access

Authors: A.S. Smirnov, A.G. Vakhromeev, I.A. Shelokhov, V.V. Kasyanov, N.N. Yaitskiy and A.V. Makarova
Event name: GeoBaikal 2018
Session: Seismic for Hydrocarbon Exploration: Theory and Practice
Publication date: 11 August 2018
DOI: 10.3997/2214-4609.201802041
Organisations: EAGE
Language: Russian
Info: Extended abstract, PDF ( 708.43Kb )
Price: € 20

Summary:
When interpreting the 2D and 3D seismic data processed with standard graph, it is impossible to detect oil and gas reservoirs (fissured-cavernous and porous-fissured types) with high properties. The reason for this - the small size of caverns and fractures, saturated with fluids with abnormally high reservoir pressures (AHRP). In particular, in the south of the Siberian craton (the Angara-Lena step) by drilling at depths of 1.2-2.2 km in the geological section of the halogen-carbonate rocks, the presence of gas- and brine-saturated reservoirs of fractured and fissured-cavernous type was established. The reservoir fluid pressures are 2.3-2.6 times higher than hydrostatic pressures. Nowadays, due to increased interest of oil and gas companies and institutions to the study of fractured reservoirs in dense rocks of the sedimentary cover and crystalline rocks of the basement, methods for modeling the propagation of seismic (scattered) waves are actively developing. The paper is devoted to the special approaches in the processing technology - the interpretation of seismic data, which are aimed at an accentuated study of a natural fissure reservoir through a "cloud" of scattered waves, which gives a field independent of fluid saturation, a dataset that is somehow related to a fracture and cavernous - with a pore space. The fractured filtration system of the intersalt reservoir, having the same properties in the acoustic field as the above / lower-lying carbonate layers, in addition or in contrast to them, is additionally characterized by the parameters of anisotropy, inhomogeneity or mosaic laterally.


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