Distribution of fractured reservoirs in the Chayanda field (Eastern Siberia)

The results of laboratory studies of nearly 1,300 samples from 50 wells of reservoirs of three productive terrigenous horizons represented by sandstones and siltstones are considered. Intergranular and fractured components mainly make up the porosity structure of reservoirs and their values influence the main parameters of rocks, including filtration-capacitive properties of reservoirs, and determine the processes of hydrocarbon field development. The spatial distribution of the intergranular and fractured components of reservoir porosity affects the development and exploitation of oil and gas reservoirs and determines the relevance of this study. The values of the fracture and intergranular component of porosity were determined by the author’s method using data on open porosity and the rate of elastic wave propagation in rock samples and the mineral skeleton of these samples during the simulation of reservoir conditions. A mosaic area distribution of fractured porosity values, caused by a long geological and tectonic history of the area development, was revealed. We identified zones of increased fractured porosity up to 0.7–0.8 % (percent absolute porosity) in the north and center of the western part of the field, and zones with minimum fractured porosity values of less than 0.2–0.3 % in the eastern part of the field. Results of laboratory core studies showed the presence of fractured porosity in reservoirs up to 1.26 %. The data on the size and distribution of fractured reservoirs across the Chayanda field area may be used to refine the field development project.