Article investigates the change in the geophysical properties of rocks in the process of extracting the rock sample from great depths. Evaluation of changes in effective elastic properties, porosity and permeability of rock samples during extraction was carried out by means of finite element modeling. Assessment of the critical dimensions and orientation of internal defects, leading to the destruction of the rock samples during extraction from great depths, has been made based on the methods of linear destruction mechanics. Approach that makes it possible to calculate the change in the mechanical properties, porosity and fracturing of reservoir rocks in the process of extracting the rock sample from depths to the surface is proposed. Use of refined data on the mechanical properties of recoverable rock samples makes it possible to increase the accuracy of digital geological models required for geological exploration, determination of reservoir properties and oil and gas saturation of a field, and development of oil and gas deposits. Application of such models is especially relevant at all stages of the fields development with hard-to-recover reserves.
On an international level, economic assessment of deposits is done through dynamic methods which take the time factor for investments and returns, i.e. the time value of money, into account and are based on compound interest formulae. The economic benefit of mining enterprise and investment's attractiveness indicated by net present value and internal return rate in dynamic investment forecast model. This study will only deal with simple cash flow calculations a geologist or mining engineer will have to make in the prefeasibility stage of a project in order to establish whether an exploration project worth pursuing.
The problem of accuracy and reliability of design decisions is a characteristic feature of the present stage in development of all material production spheres, including the mining industry. A whole range of unresolved problems still exists in enhancing reliability of open-pits designing. A lot of research publications are investigating interrelations of the accuracy and uncertainty categories with reference to specific conditions in order to solve practical problems. Scientific research in decision-making techniques in conditions of uncertainty and risk, in development of heuristic approaches, methods of stochastic modelling and programming are of utmost interest in terms of open-pit designing.
The technical and economic assessment of the development of open pits to replenish the raw material base of Karelsky Okatysh OJSC is presented. The calculation of economic risk and assessment of the feasibility of deposit development are carried out.
