Seismic instruments: article

Аnnotation: The method proposed by the authors allows us to determine the nature of changes in the two components (intergranular and fracture) of total porosity. Changes in fracture and intergranular porosity were investigated in the fracture nucleation of sandstone samples under modelling in-situ conditions. Sandstone samples were held at constant confining and pore pressure modelling in-situ conditions. At the same time, only a slight decrease in total and intergranular porosity was observed. But only in the sample with initially large value fracture porosity an increase in fracture porosity was observed. Growth of additional axial compression reduced all kinds of porosity. Fracture preparation of the sample with initially small value of fracture porosity was accompanied predominantly by a decrease in total and intergranular porosity and an increase in fracture porosity, i.e., growth of microcracks. At the same time, when preparing a fracture of a sample containing initially large value fracture porosity, an increase in total and intergranular porosity and a decrease in fracture porosity were observed, which is characteristic of dilatancy processes. Differences in the fracture nucleation of sandstone samples are revealed. It indicates that their initial fracture porosity has a significant effect on them.