Water saturation of rocks of the Bazhenov formation. New views
UDC: 622.276.031.011.431.3
DOI: -
Authors:
GLOTOV ANTON V.
1,2,
MIKHAILOV NIKOLAY N.2,3
1 "RN-Upstream design" LLC, Tomsk, Russia
2 Oil and Gas Research Institute Russian Academy of Sciences, Moscow, Russia
3 National University of Oil and Gas "Gubkin University", Moscow, Russia
Keywords: water influx, oil saturation, formation water, thermal analysis, pore waters, mineralization, wettability, contact angle, scale factor, porosity
Annotation:
Water saturation, water content, pore water properties and wettability, which are extremely important reservoir parameters, have never been the focus of attention in petrophysical core studies of the Bazhenov formation. Historically, the imperfection of methods for assessing these properties of unconventional reservoirs, multiplied by the study of the core, mainly from wells in Bolshoy Salym, showed an insignificant content, more often the absence of water in the pore space, and the wettability was characterized as hydrophobic. The method of determining water saturation and water content, developed by one of the authors on the basis of thermal and spectrometric methods, showed a significant underestimation of the water saturation of the Bazhenov formation 10 years ago. At first, this seemed to be an exception to the rule, but as the actual material accumulated (dozens of wells, thousands of samples) and the research area expanded, it became obvious that this was the rule rather than the exception. The application of the inflow intensification method, widely developed for shale reservoirs, such as hydraulic fracturing, taking into account the properties of the Bazhenov formation, implied the production of anhydrous oil inflows. However, the reality is that an oil water content of 10...30 % is considered a very good result against the background of an oil water content of 70...100 % reaching in a significant part of wells. The results, obtained by the authors, for determining the wettability on the core of the well that produced the oil inflow suggest its high variability and predominantly neutral wettability. The results of the development and laboratory studies of the core demonstrate a completely different saturation model from the generally accepted Bazhenov formation. New ideas about the saturation of rocks in the Bazhenov formation exclude its billions of hydrocarbon reserves.
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