No 11 (2014)
- Year: 2014
- Articles: 13
- URL: https://ered.pstu.ru/index.php/geo/issue/view/96
Abstract
The aim of the work is to analyze oil content of the Bereznikovskoe paleoplateau, as exemplified by open hydro- carbon deposits. The paper forecasts oil potential of the Bereznikovskoe paleoplateau resource base. The article de- scribes peculiarities of fluid properties (density of oil and produced water, gas saturation of reservoir oil, oil viscosity, content of resins, asphaltenes, paraffins, etc.) on the fields of the Bereznikovskoe paleoplateau. On the basis of the previous works the applied criteria of classification features are listed to identify oil and gas accumulation zone of the Bereznikovskoe paleoplateau. The change of physicochemical oil properties is depicted on the diagrams including three oil-and-gas bearing complexes, namely Verkhnedevonsko-turneiskii, Verkhnevizeisko-bashkirskii (carbonate) and Nizhne-srednevizeiskii (terrigenous). The diagrams of physicochemical properties of reservoir fluids show clear linear zoning. Within the paleoplateau area the lines of equal values of oil density are distributed along the lines of me- ridional direction. The north-eastern depression area and the Ural’s front folds are associated with the lightest naphthene-methane oils, having lower content of sulphur, resins, asphaltenes. The analysis, including hydrochemical features of reservoir waters, allowed identification of two subzones of oil and gas accumulation within the Berezni- kovskoe paleoplateau, in which regularity of physicochemical oil properties distribution and oil traps filling degree is found. The difference in physicochemical properties of the Famensko-turneiskii complex for the Solikamskaia depres- sion is observed. The analysis of the oil content confirms the principle scheme of condensatogenic waters of the Solikamskaia depression, offered by V.G. Popov and Yu.A. Yakovlev (2002).The results may be applied in planning exploration in the Solikamskaia depression, estimation of hydrocarbon re- serves, reservoir engineering.
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Abstract
BU Kogalymneftegaz offers strong factual evidence allowing developing a methodology to predict oil and gas po- tential BY constructing probabilistic and statistical models based on geological zones description. A special feature of this method is that only variables permanently available to producers are considered, in addition, they will be used in- tegrally, providing high reliability of obtained probabilistic and statistical prediction models of oil and gas potential.This method of oil and gas potential prediction can be performed with certain zone maturity, i.e. when a number of zones is used for analyses, some of which contain hydrocarbons in the sediment and some are hydrocarbon-free. All of these zones can be characterized by the same parameters, and these parameters can be determined before apply- ing them for further research. This helps to build probabilistic and statistical models that can be practically used in as- sessing oil and gas potential of the undrilled areas. Such method allows planning the sequence of research within the areas. It is suggested that identification of the most promising oil and gas bearing zones should be made by construct- ing geological and mathematical prediction models. It is important that in constructing the models the probabilities cal- culated on the basis of parameters, but not the different dimensional parameters themselves will be used. To obtain the necessary probabilities regression equation will be constructed. Probability values used in incremental linear dis- criminant and multivariate regression analysis will permit to develop a complex probabilistic criterion. This criterion will be used in future to build a multidimensional model directly for the zones, on the basis of which it is possible to identify priority areas recommended for further research.
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Abstract
Oil and gas horizontal well drilling is associated with big amount of challenges that may occur while drilling or completion operations. The main risk in horizontal well cementing is sedimentation of cement slurry. Unlike vertical wells where the integrity of the well is generally not reduced, even a minor water loss leads to the formation of the channel created by the mixing fluid under the upper wall of the horizontal borehole, where contact of the cement stone and rock may lack, leading to annular space flows. Obviously, the main way to improve the quality of cementing is modification of the properties of cement slurry by adjusting its composition. Introduction of various additives to a certain extent alter the basic characteristics of the cement slurry, and some of them vary considerably, improving one property results in the inevitable deterioration of others. High sedimentation stability and pumpability of cement slurry are just some of these properties. While cementing sidetracks high pumpability of cement slurry is a basic requirement for its composition. In the condition of small annulus, bottomhole pressure when pumping the slurry can reach values exceeding leak off and fracturing pressure that affects the success of the operation and subsequent well productivity. Also, considering the small size of the cement stone it must have high strength characteristics. The paper includes analysis of applying cement slurries and additives for horizontal wells. The current avenues of scientific research are chosen.
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Abstract
Complex structure of voids and low permeability of Eastern Siberia deposits - productive intervals of which are confined to Vendian and Lower Cambrian carbonate deposits - result in that the time of core samples extraction alone takes two-three months. Overall, low permeability of rocks cause prolonged time of all filtration experiments and experiments with rock satu- ration. Besides that, carbonate rocks often contain a significant amount of halite. Laboratory-based core studies on salt ex- traction from core samples indicated that void content of test samples might increase up to 30 % in absolute units, permeabil- ity might increase by 104 times. In this respect, it seems to be relevant to plan the laboratory studies of such rocks to mini- mize the time of sample interaction with water on the one hand and to obtain maximum information about filtration-volumetric characteristics of the sample on the other hand. One of the methods that can be used to obtain this information is laboratory determination of capillary pressure curves on the core samples. The present paper demonstrates the opportunity of build-up of the whole capillary pressure curve by edging point corresponding with residual water saturation.There were analyzed capillary pressure curves of samples belonging to Eastern Siberia complex structured car- bonate deposits, capillary pressure curves were obtained by the samples centrifuge method. It was detected that these curves are the function of the residual water saturation coefficient. There was suggested an algorithm of build-up of capillary pressure curves using residual water saturation. It was determined that for the section under research resistiv- ity index is not only a function of water saturation, but also of residual water saturation.
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Abstract
To improve pressure communication between the reservoir and the well and bottomhole formation area permeability and to lower skin factor acidic compounds are widely applied to treat the wells. Such a treatment allows artificial improvement of bottomhole formation area permeability thanks to a higher number and size of drain- holes. In order to intensify oil extraction from carbonate reservoirs hydrochloric acid-based compounds are mainly used.The procedure of acidic treatment of a bottomhole formation area is chiefly determined by three parameters: surface reaction rate, acid diffusion, and acid injection rate. For any given set of reservoir conditions there exist a critical rate of acid injection. If injection rate is below critical, compact rock surface dissolution occurs; if it is higher solution channels (wormholes) are formed.In laboratory conditions a test series of acidic solutions was carried out on real core samples with reference to 12 % HCl/water solution, they are 12 % HCl/water solution with HCl retardant, water solution of dry acid compound and multi-functional acidic compound.For the tests carbon cores of productive sediments of gas and oil deposits were used. Laboratory tests of rock solution rates using acidic compounds were performed. An estimate is given to reaction rate retardants used in the compounds investigated.Under different reservoir temperatures filtration tests were performed to evaluate effects of acidic compounds on cores. Optimal rate of acidic compound injection is confirmed, allowing formation of the dominating high-conductive solution channel with a minimum volume of acidic compound.
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Abstract
One of the ways to develop hydrocarbon resource potential is to get access to unconventional deposits like high-viscosity oil. Reservoirs with high-viscosity oil are common mostly in the European part of Russia. In Perm kray the share of unconventional oil reserves reaches 30 %. The paper analyses the development of a typical site exploiting the Tournaisian deposit with high-viscosity oil in Perm kray. The Tournaisian deposit consists of three in- terlayers: Т0, Т1-1, Т1-2. In the main part of the wells only sublayer Т1-1 has been opened by perforation, which con- ditions uneven recovery, pressure wells being in the same state. It is found that high-viscosity oil predetermines low hydraulic permeability of productive formation, which causes low well output and, naturally, low annual deposit development rate. Recovery of reserves is carried out slowly and unevenly in terms of area and section. High water cut of the oil extracted with low production is observed. To improve draining procedure of oil deposits several techniques of reservoir stimulation are required. To isolate the watered sublayers it is essential to perform an in-depth geophysical study of wells to find out the causes and source of water intrusion, followed by repairing and isolating. Possibility of polymer flooding is estimated, as well as injection of micellar solutions and heating agent.
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Abstract
The paper deals with a methodological basis for determining the energy resource of mechanical transmission parts for mining machines. Based on the analysis of the accumulation of damage in metal gears, a method of estimating residual life of coarse-toothed wheels by periodically measuring the hardness of the surface layer of the teeth is justified. The regulari- ties in change of hardness of coarse-tooth gear, conditioned by a change in metal strength properties that take into ac- count the micro- and macromechanisms of plastic and elastic deformation, distortion of the metal crystal lattice with forma- tion and movement of vacancies and dislocations. Experimental setup was built and the results of laboratory experiments are given related to the process of destruction of non-standard samples under tension, pure alternating bending, combined bending and tensile loads. The parameters of the samples deformation and changes in the local hardness of the metal in the regions adjacent to the fracture surface are found. Comparison of dimensions and hardness values of the sample al- lows concluding that a larger deformation corresponds to a greater increase in hardness, their limit value for the material being in the fracture zone. It is established that the detected changes in the local hardness occurs in areas of increased stresses above the limit of proportionality and the work of fracture forces attributed to dislocations density adjacent to the fracture plane expressed in terms of hardness increment is constant.
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Abstract
Buntons and conductors of shaft equipment during operation are subjected to mechanical wear due to constant force interaction with conveyance and corrosive factors exposure affected by mine environment conditions. During prolonged operation shaft wear caused by these processes is uneven along the length of conductors and bunton beams, as well as within the sections located at different shaft depth. Considering this it is urgent to study the effect of parameters of residual section of metal wear equipment on their strength characteristics during the long-term use. The main causes of equipment wear are significant reversed vertical deflection of conductors, lack of proper effectiveness of the work of roller guide vehicles and corrosion provoked by exposure to aggressive mine environment. Due to lack of standards and measures for technical supervision of buntons mechanically they prove to be most often the weakest unit in the «conductor - bunton» system. The article shows that the wear rates of the conductors in the frontal and profile planes are different and depend on the dynamics of the «vehicle - equipment» system. The research made allows establishing the influence patterns of the geometric parameters of beams and conductors buntons on the equipment strength, which results in a more effective approach to choosing assortment of shaft metal components when carrying out design and repairs.
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Abstract
The paper presents results of the studies carried out in 2011-2013 on gas content and outburst hazard of saliferous rocks at potash deposits in Kazakhstan at the exploratory drilling stage. The studies aimed at determining the gas content and blend composition of natural gases of productive strata and reservoirs, acquiring input data to evaluate mine ventilation and forecasting potential outburst hazard during field development. The research procedure included degassing of core samples of exploration wells by dissolution in the preliminary degassed water, analysis of gas show during drilling and drilling fluids research, data analysis using physical-mechanical properties of saliferous rocks. A short geological description is given to the Zhilianskoe and Satimola potassium salt deposits. Average values of gas content and blend composition of associated gases are given for lithological variety of rocks and deposits in general. The research discovered a strong relation between the content of hydrogen and methane in the samples. The value of overall content of free and associated gases, estimated relative gas abundance in productive strata and reservoirs are determined. The gas shows occurring during the exploratory drilling at the Satimola deposit are described. The analysis of the registered outbursts and foaming of drilling fluids is made. A map of gas shows over the deposit area is produced. Rock dislocations within the intervals of drilling fluid ourburst are observed. On the basis of the data obtained preliminary conclusions about outburst hazard of the deposit rocks are given.
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Abstract
A problem of the stress-deformed state (SDS) of the well is solved. To calculate SDS a 3D application of finite-difference engineering analysis FLAC3D is used. A part of reservoir evenly saturated at the initial stage is considered, at the center of which a well is located. The solution has two steps. Step one relates to geostatic load; step two concerns reservoir pressure change due to flow rate specification on the well radius. The problem is approached as connected, which means simultaneous addressing correlations of mechanics and hydrodynamics. Reservoir pressure changes over time and so does actual stress. The Hooke’s law is chosen as the foundation for physical relations, i.e. elastic model of material behaviour is used. Fluid filtration follows the Darcy’s law. The paper suggests a mathematic setting of the problem embracing correlations of the elasticity theory, filtration law and boundary conditions. To process the results an application was written in FISH, the internal language of FLAC3D. Dependences are obtained of dimensionless reservoir pressure on dimensionless radius, as well as dimensionless stresses on dimensionless radius for a given period of time.
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Abstract
The paper presents motivation for a new technique of field measurements of natural tectonic stress and deformation modulus of the largest spacings and massifs (comparable with reservoirs and mining claims) documented in geomechanics is presented. Open pits and caves formed during the underground mining by systems with sloughing are chosen as active vesicles. The method is based on using the results of the direct satellite measurements (GPS, GLONASS and others) of the shifting reference marks preinstalled near the active vesicles within the zone of elastic deformation of the massif followed by converting the deformations measured into the components of a natural stress field and a massif elasticity modulus. Open pits and caves are approximated by elliptic and round holes made in the elastic preliminary stressed isotropic plane in the stress-deformed state. Displacement of reference marks, caused by hole removal, is determined as a difference between the shifts conditioned by loading the plane with holes and the shifts related to the loading of the same plane without holes. The method described allows taking account of space-time variability of stress and deformation fields, determined by block-hierarchical structure and different rock moduli. An example is offered of measuring stress-deformed state of the Trubka Udachnaia deposit massif developed by OJSC ALROSA.
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Abstract
Main negative consequences of moisture precipitation at the air intake openings of mines during the warm periods are discussed. General data on the damage inflicted by condensate brines in the openings of potash mines are presented. The work suggests a technique of air intake openings dewatering by the systems of partial air reuse. The subject of the research is heat and mass exchange processes in rock openings while applying the systems of partial air reuse. As a result, a model is designed of transformation of the mine air’s thermodynamic parameters during recirculation ventilation, taking account of heat exchange between the mine air and the massif, on the basis of a model with non-stationary heat transfer coefficient. Using the data obtained, a technique of evaluating thermal and humidity parameters of mine air in recirculation contours of ventilation network using partial air reuse was developed. With the help of l-d diagrams thermodynamic processes in the mine openings environment at recirculation contours are analysed both with and without moisture occlusion by the massif. Equations are generated to determine moisture precipitation rate in the air intake openings and distance of the initial moisture precipitation. The factors conditioning effectiveness of recirculation ventilation to dewater transport openings of potash mines are revealed. It is found that effectiveness of recirculation ventilation depends on, besides aerodynamical features, occlusive moisture exchange between mine air and the massif in all parts of recirculation contours.
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Abstract
As reserve development is getting complicated, maintaining high oil recovery factors on depleting deposits, ensuring higher volumes of oil transfer via main pipelines and in-field pipeline systems, preventing and solving operating problems require chemical agents coupled with physical-mechanical methods. Application of the latter imply a highly qualified personnel and schools of broad thinking based on deep knowledge in many allied disciplines. And the critical point is that instead of ‘pure’ chemists ‘universal’ specialists are needed who possess a great knowledge of chemistry, physics, mathematics and oil industry. In this respect, oil-field chemistry is supposed to offer new opportunities. This is a science about chemical processes involved in oil extraction, transfer and treatment, as well as prevention and eradication of problems, professional application of chemical agents, estimation of geological conditions of field development and variations of reservoir fluids properties. Thus, there is an urgent need at the level of the industry and the state to establish at the oil institutes or polytechnic institutes’ faculties the departments of oil-field chemistry offering inter alia post graduate courses in order to train qualified chemical engineers for oil industry, to carry out research into new agents and technologies starting from screening to implementation and engineering services, to blend the efforts of university and academic science. Naturally, the course of oil-field chemistry would require special curriculum, tutorials and study guides. Oil-field chemistry is a full-right discipline, capable of meeting the needs of oil industry and ensuring a shift from knowledge summarizing to its intense development.
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