One of the most important parameters, which have high influence on screw compressor characteristics, are rotors' profile clearances. They determine in general the smooth of the rotors' gearing and ...influence on the screw compressor vibration level. Analyse of actual rotor profile clearances depending on the actual rotor temperature fields and on the manufacturing imperfection was done. Specially profiled milling tools were chosen as rotor profile manufacturing tools. Following four types of the manufacturing error, which have the highest influence on the accuracy and quality of rotors' profile surface, were chosen to analyses: the centre distance deviation between the rotor and the milling tool axises (dAi), the departure of the milling tool position from their basic plate (dZf), the milling tool mounting position angle departure (dβ) and the milling tool radii departure (dRf).The actual screw compressor profile coordinates can be obtained by taken into account all factors presented above. They determine the actual rotor profile clearances on "cold" state when screw compressor is on shutdown conditions and can be measured during a compressor assembling or a compressor stripping. However, it should be noted that they are changed depending on the screw compressor working conditions. To correctly determining actual profile clearances depending on working condition also needs to take into account rotors' thermal deformation. The presented multifaceted approach of the screw compressor actual rotor profile clearances calculation improves an accuracy compressor characteristic obtained by their mathematical model. A deep analysis of the obtained results can pointed to the rotors' manufacturing factors, which should be improved firstly during the compressors' mass production.
The international interest in shale oil has recently provoked special attention to the Russian unconventional oil-source formations, including the Bazhenov Formation of West Siberia, domanik deposits ...in the Volga–Ural region, and the lower Maikop Group of the Cis-Caucasus. High contents of para-autochthonous soluble organic matter (bitumen) in clayey–carbonate, clayey–siliceous, carbonate–clayey–siliceous rocks with low filtration–capacity properties results in significant uncertainties in the identification of the generation potential of organic matter (OM). Examination of a large database on the OM of the Bazhenov Formation allowed us to propose an optimum complex technique for study of the source rock potential and assessment of the amount of produced hydrocarbons in the kerogen-rich sediments. The investigations include a combination of Rock Eval pyrolysis prior to and after extraction with different solvents, the comparison of bituminological and pyrolytic characteristics, and the determination of the group composition of soluble organic matter, as well as chromatography and chromato-mass spectrometry.
In general, screw compressor characteristics depend on their working chamber clearances. One of the main of clearances in the working chamber of screw compressors are the clearances between rotors' ...profiles, which are produced due to a reducing of theoretical rotor profiles. This reducing is made to compensate thermal deformation, manufacturing errors and other negative factors, which occur during the screw compressor working cycles and may cause a rotors' teeth interference. This also may result in a transmission error, which increases the rotor profile clearance on one side of rotor tooth and reduces on other. A screw compressor rotor gearing mathematical model which can predict the actual rotor position and value of the transmission error was developed. An analysis of compressor working conditions influence on the transmission error value is done. Results of the presented work are used for working process mathematical models for improving their accuracy. They also may be used as basis for development of reducing theoretical profiles methods with the aim to reducing of the rotor profiles' clearances and improve screw compressor characteristics.
The vibrational state of the screw compressor is largely dependent on the gearing of the rotors and on the possibility of angular backlash in the gears. The presence of the latter leads to a ...transmission error and is caused by the need for the downward bias of the actual profile in relation to the theoretical. The loss of contact between rotors and, as a consequence, the current value of the quantity, characterizing the transmission error, is affected by a large number of different factors. In particular, a major influence on the amount of possible movement in the gearing will be exerted by thermal deformations of the rotor and the housing parts in the working mode of the machine. The present work is devoted to the analysis of the thermal state in the operation of the screw oil-flooded compressor and its impact on the transmission error and the possibility of losing contact between them during the operating cycle.
The problem of studying the Domanik deposits and their reservoir potential is among the most important ones. The discovery of hydrocarbon deposits in similar rocks at various depths, the considerable ...variability of reservoir properties, and ambiguity in establishing the values of the effective thickness set the task for researchers to estimate them more reliably. The high-carbon kerogenic-carbonate-siliceous stratum that is characterized by the development of differently-oriented systems of fractures is of outstanding interest.
The article presents a complex of laboratory core analyses conducted at the Center for Petrophysical and Geomechanical Research, Schmidt Institute of Physics of the Earth, Russian Academy of Sciences ...(CPGR IPE RAS). The complex provides for multiscale studies of the elastic properties, microstructure, composition, and porosity and permeability properties of rocks. The laboratory studies determine the dynamic and static elastic moduli, rock strength and creep parameters, and acoustic emission characteristics; 2D and 3D microstructure analysis is also performed. Dynamic elastic moduli are determined both under normal and reservoir-simulating conditions. Under normal conditions, multilevel ultrasound examination of samples is carried out; its results, together with those of microstructure analysis, are then used to determine the degree of inhomogeneity of the elastic properties of a sample, to reveal the anisotropy of these properties, and to compare the elastic properties of rocks at different scales. The results of geomechanical rock tests are necessary for constructing geomechanical models of reservoirs. The elastic parameters determined under normal and reservoir conditions are the basis for constructing correlation dependences that allow the geomechanical properties and principal stresses under reservoir conditions to be forecasted from well log data. Data on the elastic properties and microstructure of samples are used to construct different-scale models of the elastic properties of rocks under normal and reservoir conditions using petrophysical methods; these models further serve as a basis for petroelastic modeling of hydrocarbon fields and for predicting the viscoelastic behavior of rocks.
The reservoirs of the oil-bearing Tutleym formation, Bazhenov horizon (analog of the Bazhenov Formation for Middle Nazym Oil Field), are studied. Their material composition, porosity and ...permeability, the geochemical characteristics of their organic matter, and pore space characteristics are examined, and the factors affecting the reservoir porosity and permeability are found. The changes in the structure of the porous medium, which provide primary oil migration from oil source rocks into the Tutleym formation reservoirs, are revealed.
The possible reservoir type of the Bazhenov Formation relative to the intervals enriched in phosphates (apatite varieties) is described in this work. The phosphate rocks are characterized by a highly ...developed pore space; their porosity can reach up to 14%. Along with this, these rocks have explicit geochemical characteristics of oil-reservoir rocks in comparison with other rock samples in the well. As an example, the productivity index and oil-saturation index for phosphates are twice as high as the background values. The composition of such rocks can slightly vary: fluorine can be observed in phosphate minerals, while the rock is always enriched in organic matter (>8 wt %).
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