Perm Journal of Petroleum and Mining Engineering

During the last years drilling exploration works in the Republic of Azerbaijan have been moved from east regions to less studied central and west regions. Besides, generalization of available geological and geophysical data, evaluation of potential of certain lithologic and stratigraphic complexes and forecast of deep oil and gas reservoirs are of particular importance. The paper shows an analysis of complex petrophysical data. An analysis considers interpretation of reservoir and petrophysical properties of rocks of Mesozoic and Cenozoic deposits taken from drilled wildcat and appraisal wells and geological data of Kalamaddin oil and gas bearing region where sediments of productive thickness (PT) such as Lower Pliocene are widely spread. As a result of an analysis and interpretation of geological, geophysical and petrophysical material it was established that oil and gas bearing reservoirs are represented mostly by naturally fractured igneous-sedimentary and carbonate rocks. Petrophysical properties of rocks of a section of the earth’s crust of Kalamaddin oil and gas bearing region are given in short. Based on the generalized data a schematic graph that reflects change in rock porosity along a section is built. According to a graph the deeper is the formation the lower rock porosity and the higher the density and propagation velocity of ultrasonic waves are. Obtained generalizations allow to conclude that change in reservoir properties in a wide range on the territory of Kalamaddin is connected to lithological heterogeneity of rock complexes, diversity of their burial depths and as a result with diversity of pressure and temperature conditions and complexity of tectonic conditions. Results of different petrophysical study methods show that reservoir properties of rocks become worse if depth is increased. Nevertheless, in certain cases reservoir properties of clay and carbonate rocks can be improved due to secondary porosity under relatively rough pressure and temperature conditions. Besides, relations between physical parameters and matter composition for certain rock types are established. Studies were performed in atmosphere and thermodynamic conditions.

The article is devoted to the problem of evaluation of oil displacement coefficient. Determination of oil displacement coefficient is essential stage for estimation of recoverable reserves, feasibility study of oil recovery factor and control of field development. Complexity of its laboratory determination is caused by labor intensity and duration of a process. When the number of cores is not enough for flow experiments or absent oil recovery factor is evaluated either similarly to neighbor fields or by analytical dependencies that are important to obtain. During the generalization and analysis of a significant amount of experimental data the authors developed a method for estimation of oil displacement coefficient without its laboratory determination. A proposed method is based on use of data from previous studies to built statistical models for estimation of displacement coefficient using linear step-by-step regression and discriminant analysis. In order to implement the method along with oil viscosity, knowledge of reservoir parameters such as porosity, permeability, irreducible water saturation and bulk density of a rock, determined by conventional core studies, is required. The main stages of implementation of the method for Visean clastic deposits of the Bashkir arch and Solikamsk depression of the Perm Region are presented. Results of implementation of the method for Bashkir carbonate deposits of the indicated tectonic elements are presented as well. Analysis of initial data allow establishing that there are classes of values for which regression equations are statistically justified. According to the equations model and experimental values of the displacement coefficients are very close to each other. It was concluded based on parameters of the equations that there is abnormal influence of initial oil saturation on the displacement coefficient. It is shown that for reservoirs of low flow characteristics a displacement coefficient is determined by their capacitive properties.

Results of geomechanical modelling of a stress-strain state of salt rocks in conditions of layer mining at mines of Belaruskali JSC are reviewed. There are sudden powerful gas dynamic phenomena (GDP) occur from the bedrock of mines such as salt and gas emission, bedrock destruction followed by gas release. Moreover, there are areas that are potentially dangerous due to gas dynamic phenomena acting from the bedrocks. For the conditions of the Starobinsk deposit of potassium salts gas accumulations in bedrocks of mines are usually confined to clayish interlayers and layers in salt rocks. Therefore, it is assumed that disclosure of clay contacts is a geomechanical prerequisite for GDP. That leads to formation of channels for migration of free gases and formation of artificial gas-saturated zones under the influence of mining operations. Task statement includes setting of parameters for collapse of the roof rocks of the Third potash formation being under the mining, localization of plastic deformations in the enclosing rocks and opening of clay contacts in a salt thickness. It is taken into account that collapsed rocks of a long face roof fill the goaf and form technogenic geo-environment with respect to their decompaction. The geo-environment is also included in the calculation scheme of mathematical modeling. In order to determine a stress-strain state of rocks, a model of an ideal elastic plastic medium with internal friction is used. In this case, clay interbedding are described by Goodman's contact elements. Based on results of solution of a number of model problems in a two-dimensional statement, there is a conclusion made on the significant influence of clay interbedding in the bedrocks of a formation under the mining on the possibility of occurrence of gas dynamic phenomena. It is established, that in presence of three and more clay contacts in the layer of underlying halite there are conditions created for formation of a multi-stage focus of GDP, formed when gas-saturated clay contacts are exposed. Periodic character of formation of GDP focuses is noted during the movement of the front of cleaning works.

Today geological active zones unite active faults of lithosphere especially earth’s crust and caused by them zones of increased permeability such as paleo-valleys and underground water flows, karst and geological bodies, that are different in terms of composition and structure from the enclosing rocks. There is an evidence that mortality in geologically active zones increases dramatically, mental instability is detected and road accidents are more frequent. The purpose of this paper is to estimate the frequency of suicides among the residents of Saint Petersburg living above the geologically active zones and outside these zones and the influence of geomagnetic and gravitational disturbances on them. The dynamics of suicides among residents of 446 high-rise building in the territory of the Kalininsky and Vasileostrovsky districts of the city of Saint Petersburg is analyzed. Geological structure of those buildings was most studied. From 1999 to 2003 there were 268 suicides among the residents of such buildings. The group A included homes that were at least 40 m above the nearest tectonic fault. Group B included residential buildings located above or in the immediate vicinity of the faults. During the geomagnetic storms, full moon and new moon periods the number of suicides in a group A decreased. Magnetic storms and gravitational disturbances did not affect the frequency of suicides in a group B. There is also no significant correlation between dynamics of suicides and daily values of the K -index of the geomagnetic field, as well as between dynamics of suicides and the 3-hour geomagnetic activity in both groups. Results of studies presented in this paper show that there is no evidence of a significant negative impact of tectonic faults on people living above them.

The article presents results of studies aimed to develop parameters for preventive gas removal of mine bedrocks occur during the layer mining of the Third potash formation in conditions of Belaruskali JSC mines. Development of parameters for preventive gas removal of bedrocks was carried out based on results of mine experimental studies of gas content, gas dynamic characteristics of bedrocks and experimental studies of dynamics of pressure of free gases under different mine industrial conditions of layer mining at the Third potash formation. A method of mine experimental research consider quantitative assessment of the indicators such as gas content of bedrocks on free gases, initial velocity of gas emission from bedrocks, pressure of free gases of bedrocks. Study of dynamics of change in time of pressure of free gases in bedrocks of the preparatory excavations were carried out in excavation poles of long faces that mine layers 2, 2-3 and 3 of the Third formation. That was done with help of measuring stations (packers) equipped for measuring the pressure of free gases in the measuring chambers by digital manometers. Based on results of mine experimental studies, regularities of formation of focuses of gas dynamic phenomena in bedrocks were established. Regularities consider various mining conditions of layer operation of the Third potash layer. Parameters of preventive gas removal drilling of wells into the bedrocks of preparatory excavations for long faces that mine layers 2, 2-3 and 3 of the Third potash layer in various geological and mining conditions have been developed. Parameters consider established regularities of formation of focuses of gas dynamic phenomena in bedrocks. Parameters of preventive gas removal drilling for various technological schemes for operation of the Third layer include a list of excavations in the long faces where preventive gas removal drilling should be applied and diameter, depth and distance between the degassing wells. Introduction of schemes of preventive drilling of degassing wells into the bedrocks of preparatory excavations of long faces that mine layers 2, 2-3, 3 of the Third potash layer allows to increase safety of mining operations at the mines of Belaruskali JSC.