Analysis of changes in Bazhenov formation rock properties as a result of high-pressure air injection based on laboratory modelling data

UDK: 622.276.6

DOI: 10.24887/0028-2448-2017-3-40-44

Key words: Bazhenov formation, combustion tube, high-pressure air injection, reservoir properties, nuclear magnetic resonance (NMR), thermal conductivity, coefficient of anisotropy, kerogen

Authors: T.M. Bondarenko, A.Z. Mukhametdinova, E.Yu. Popov, A.N. Cheremisin (Skolkovo Institute of Science and Technology, RF, Moscow), A.G. Kalmykov (Lomonosov Moscow State University, RF, Moscow), I.A. Karpov (Gazpromneft NTC LLC, RF, Saint-Petersburg)

To assess the effectiveness of high-pressure air injection into layers of the Bazhenov formation and to analyze changes in properties of rocks under chemical and thermal exposure during experiment, the main experiment of air injection in the combustion tube and a number of additional studies of samples packed were carried out. A series of additional experiments included: a study of cylindrical samples in NMR relaxometer to obtain saturation profiles along the core samples prior to and after the experiment in the combustion tube; thermal conductivity measurements for evaluation of their changes as a result of the combustion front propagation through the samples; measurements of porosity and permeability of the cylindrical samples to assess changes in reservoir properties under chemical and thermal exposure. Integration of studies listed above has allowed to determine the dynamics of the physical and chemical state of rock samples prior to and after exposure. Porosity and permeability of samples after combustion front propagation significantly increased, while the porosity of some samples reached 32%, and permeability reached 5.77 mD. The results of measurements of the thermal properties indicated the displacement and oxidation of hydrocarbons in the cylindrical samples. Due to the low thermal conductivity of air that fills the voids formed, thermal conductivity of samples decreased. Due to the cracking thermal conductivity anisotropy of the samples increased. By analyzing saturation profiles one can assess the progress of the combustion front propagation through the samples. In all samples studied, a decrease of NMR porosity indicated the organic matter conversion.

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