The influence of structural and lithological features on the saturation model of Middle Carboniferous reservoirs of the Republic of Bashkortostan

UDK: УДК 553.98(470.57)

Key words: petrophysical classes, limestone, dolomite, oil field, petrophysical model, interpretation model, voids type, volumetric parameters, geophysical surveys, unit, tectonic region

Authors: A.M. Khusainova, T.V. Burikova, O.R. Privalova (BashNIPI-neft LLC, RF, Ufa), A.N. Nugaeva, R.I. Zianberdin (Bashneft-Dobycha LLC, RF, Ufa)

The article describes the developed unified interpretation model, individually approaching each middle Carboniferous object and able to highlight the geological characteristics of rocks, influencing the formation of void space and hence hydrocarbon saturation. Detailed lithological and petrographic study of middle Carboniferous rocks allowed identifying the main lithotypes for each stratigraphic unit. Facies conditions of rock formation and characteristics of sedimentation basin at different period of time were considered in lithotype determination. This approach allowed us to separate the rocks by their petrophysical parameters, and to justify the petrophysical classes determination by geological features of middle Carboniferous section. Petrophysical models were developed based on the results of all currently available capillarimetry studies of middle Carboniferous deposits of the Northern part of Bashkortostan. PLT data were used in studying the lithological composition and they help to determine the mineralogical composition. To analyze pore space structure of the pore space in addition to indirect methods such as acoustic and traditional methods – thin sections study, we used special methods such as tomography that helped us to justify the typification of rocks according to pore space structure. We arranged 7 petrophysical classes: 4 for limestone and 3 for dolomite. Based on petrophysical model there were created an interpretative model including lithologic differentiation of the section (dolomite, limestone, shale), reservoir determining and key logging parameters. Application of these dependencies confined to a certain study area, allows approximating estimated log parameters to core data of the fields on the territory of the Republic of Bashkortostan.
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