Известия Томского политехнического университета: Инжиниринг георесурсов (Dec 2021)

FEATURES OF MINERAL COMPOSITION OF LOW-PERMEABLE SILICEOUS-CLAY RESERVOIR ROCKS FROM THE BEREZOVSKAYA FORMATION IN THE NORTH OF WESTERN SIBERIA

  • Lyudmila G. Ananyeva,
  • Alexandr A. Doroshenko,
  • Sergey S. Ilenok,
  • Yana O. Karymova,
  • Michail V. Korovkin,
  • Yulia A. Maksimova,
  • Alexey V. Pesterev,
  • Oleg N. Protsky,
  • Olesya V. Savinova,
  • Maria O. Khrushcheva

DOI
https://doi.org/10.18799/24131830/2021/12/3275
Journal volume & issue
Vol. 332, no. 12
pp. 114 – 123

Abstract

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The relevance of the study is caused by the need to develop the oil and gas industry in Western Siberia by identifying unconventional (including low-permeability) reservoirs and assessing their prospects for development. The aim: to increase the efficiency of gas production by studying the influence of the structure of the mineral substance of rocks on the pore space and identifying unconventional reservoirs. Objects: Senonian deposits, the commissioning of which is planned to support production in the gas industry. Methods: optical and electron scanning microscopy, X-ray spectral and X-ray fluorescence analysis, Infrared spectroscopy, X-ray diffraction, analysis of filtration-capacitive properties by the GRI–SMP-200 method. Results. The features of the mineral composition of low-permeable siliceous-clay reservoir rocks of the Berezovskaya formation in the north of Western Siberia are studied on the example of the Medvezhye deposit. The chemogenic-biogenic origin of these sedimentary rocks is confirmed by the remnants of organic material: sponge spicules, radiolarian shells, mollusks, etc. The rock structure reveals small pores filled with kaolinite and quartz, and individual grains of montmorillonite. Also, there are numerous spherical aggregates of framboid pyrite (FeS2), which is an autigenic early-diagenetic biomineral and characterizes the reduction zone of diagenesis. It is shown that the «crystallinity index» which characterizes the degree of transformation of the opal-cristobalite-tridimite phase (OCT-phase) of silica can be chosen as a lithological and mineralogical criterion for identifying productive zones in unconventional reservoirs of the Medvezhye deposit. The appearance of the crystalline phase of quartz from unstable chemogenic-biogenic amorphous silica causes the appearance of larger voids, increasing gas saturation and gas permeability.

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