Nowadays Bazhenov formation is one of the major points of interest for tight oil production in Russian Federation. Bazhenov formation specifics includes complex mineralogical composition varying along vertical and lateral direction, high organic matter content and its transformation products, unusual pore structure and reservoir properties evaluation uncertainty. Bazhenov formation organic matter can be represented both as solid unsolvable in organic solvents kerogen, and as hydrocarbon compounds (HCC). HCC can be in movable or in bound state depending on their composition, position in pore structure and reservoir temperature. Thus, choosing the way of core samples preparation for correct petrophysical properties evaluation, movable fluid amount estimation and usage of core data for adjusting logging based porosity determination method, is a serious challenge. For Bazhenov formation porosity estimation by acoustic log, neutron log and density log, it is necessary to take into account influence of complex composed argillaceous minerals and, especially important to take into account kerogen influence that has contrast physical properties. As an alternative method, magnetic resonance logging can be used to determine porosity. Magnetic resonance logging data must be interpreted using transverse relaxation time cutoff adjusting to appropriate core data to obtain effective porosity.
References
1. Petersil’e V.I., Komar N.V., Frenkel’ S.M., Methods for the Bazhenov formation reserves assessment (In Russ.), Geologiya nefti i gaza, 2018, no. 5, pp. 51–59, DOI: 10.31087/0016-7894-2018-5-51-59
2. Alekseev A.D., Antonenko A.A., Zhukov V.V., Strizhnev K.V., The differentiated approach of the reserves estimation for source rock formations (In Russ.), SPE 182074-RU, 2016, DOI:10.2118/182074-MS
3. Rylander E. et al., NMR Т2 distributions in the Eagle Ford shale: Reflections on pore size, SPE-164554-MS, 2013, DOI:10.2118/164554-MS
