West Siberian Bazhenov rocks: deformation behaviour and strength properties

The authors present the results of laboratory analysis of lithological composition, Organic Matter content, deformation behaviour and strength properties of 35 samples of Mesozoic Bazhenov bituminous argillaceous-carbonate-siliceous rocks taken in Sredneobsky Petroleum Region. According to the content of main rock-forming components and Organic Matter, the studied samples are classified into three lithological types, they are: high-carbon argillaceous-siliceous-carbonate and carbonate-argillaceous-siliceous, and carbonaceous argillaceous-siliceous rocks. Each lithotype is characterized by specific values of the parameters studied. It is found that the increase in Organic Matter content in rocks is accompanied by a change in the breaking strength of bituminous rocks, which impacts on their deformation behaviour and strength properties. The first cracks appear in high-carbon argillaceous-siliceous-carbonate (coccolithophorid-bearing) rocks containing 19% of Organic Matter on average at overburden load of 66.9 MPa; next - in the high-carbon carbonate-argillaceous-siliceous rock containing 12.5 % of Organic Matter at overburden load of 67.4 MPa; and then - in carbonaceous argillaceous-siliceous rocks containing 7 % of Organic Matter on average at overburden load of 71.6 MPa