Vol 16, No 1 (2017)
- Year: 2017
- Articles: 10
- URL: https://ered.pstu.ru/index.php/geo/issue/view/106
Abstract
The paper contains results of comprehensive studies of well logging data and laboratory study of the core. Studies were carried out to determine lithologic composition and reservoir properties of clastic formations of Baklanovskoe field. It is noted that grains that compose clastic rocks are diversified in size, shape, degree of roundness and sorting, granulometric and mineral composition, type and composition of cement, its structure and ratio with grains. It is stated that these features of rocks determine structure of pore space, as an ordered set of mutual relations of elements of different hierarchical levels (for example, mineral grains, samples and rock formations). It is noted that study of pore space structure, reservoir properties and lithologic features is performed based on fractional composition of rocks. However, it is impossible to understand in details entire section of even exploration and prospecting wells in case of poor core recovery. Therefore layer-by-layer description (including wells with no core) is carried out based on logging linked to results of core analysis. It was found that logs can be used for lithologic distinguishing and selection of lithologic series of clastic rocks with its material composition determination. Information about lithologic series also allows approaching to a solution for the problem of cyclic sedimentation. Equations of multiple correlations between reservoir properties of rocks and amount of psammite, silty and pelitic particles in rock matrix. It is possible to determine porosity by recorded natural radioactivity on gamma ray charts. Solving the above mentioned problems is considered on the basis of a systematic structural approach.
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Abstract
Separation of well section into permeable and impermeable parts is one of the main problems for further construction of a geological model, reserves estimation and field development planning. Quality of separation depends on amount of knowledge about geological section, level of theoretical development of well logging methods and general geophysical characteristics of the area. The fullest differentiation is obtained by using a complex of geological and geophysical methods. The paper is focused on Visean deposits of well of Sofyinskoe field drilled in 2014. A complex of activities was performed along with well logging. Porosity was calculated by acoustic and neutron logging. Core analysis was performed. Using well logging and results of core analysis selection was made, used for construction of statistical models. Based on statistical models all parameters were made-up to a single measurement system. The analysis of degree of influence of geological and geophysical parameters was made. The geological analysis shows that the greatest influence belongs to porosity and residual water. The geophysical analysis shows that the greatest influence belongs to hydrogen content and own radioactivity of rocks. A complex probabilistic parameter that includes all measurements according to core and geophysical parameters is calculated. Results of core analysis are considered fully in order to obtain a highest degree of difference. Almost all the parameters of geophysical data increase the degree of difference, except for lateral logging, microgradient and micropotential tools and transit time of P-wave for short tool, which reduces the degree of difference. Based on values of a complex parameter that have maximum differences in geological and geophysical parameters, relationships of geological and geophysical parameters were built. Scatter charts show that fields of measured points are not intersected, which confirms a correct separation of a section. Using a statistical method allows to consider fully available geological and geophysical data to separate a section into permeable and impermeable parts.
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Abstract
In general, reliability of industrial and civil units is determined by strength and deformation properties of foundation soils of structures. On the one hand, calculated values of mechanical properties largely depend on technogenic load on a ground base, and on the other hand, on content of bound water in soils, especially clays. Many Russian and foreign scientists were engaged in evaluation of bound water in clays. Their works describe an effect of mineral composition, initial moisture and composition of clay exchange cations on thermal dehydration of bound water. It was found that the smaller the size of clay particles, the sharper dehydration curves diverge in a high-temperature area. The conclusion is drawn that there is no significant discontinuity in values of energy, corresponded to active centers on basal facies and crystal chips. The paper presents results of studies of change of properties of bound water in clays under influence of high temperatures and pressures. To researchers' mind, during compaction of clays saturated with water, free water of large pores is first to be removed, then under 1-3 MPa load osmotic water, and under pressure of more than 10 MPa structured hydrate layers begin to be removed. Closest to a hard surface water layers, which determine moisture content in clays, are not squeezed out at tens of megapascals, when monolayers at loads of hundreds of megapascals. As a result of studies conducted it was experimentally established that in kaolinite and montmorillonite clays content of film and absorbed water of the colloid, as well as surface water and water of hydroxyl groups of minerals varies with change in pressure magnitude. It is established that studied parameters influence total water loss differently, which is confirmed by various mathematical models. However, in all cases, except for montmorillonite subjected to pressure of more than 1000 MPa, the most important factor determining the overall loss of water mass is adsorbed water of minerals.
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Abstract
The aim of the work is to increase efficiency of well completion under conditions of water inflow by use of viscoelastic gas-liquid mixtures to shut-off permeable formations. At present, there is an increase in rates of drilling of wells in abnormal conditions, such as abnormal formation pressure (both low and high), unstable rocks, rocks of high hardness, permafrost etc. The quality of well construction in such conditions influences subsequent development and operation of the field greatly. Aquifer isolation is an extremely important issue due to the fact that from them water breaks through in production wells which has a significant impact on quality of fluid produced. The main solution for water breakthrough challenge is formation isolation, which is performed by use of various plugging material. At present, there are many mixtures that limit water inflows such as fast-setting plugging materials, gel-cement mixtures, polymeric swelling nets, latexes, synthetic resins, viscoelastic mixtures, materials for selective isolation etc. Under conditions of abnormally low reservoir pressures, it is important to consider density when selecting drilling fluids and plugging materials. Therefore, it is recommended to use screens based on viscoelastic three-phase stabilized gas-liquid mixtures for temporary blockage of permeable aquifer. With use of such mixtures liquid penetration flow rate is significantly reduced compared to other viscoelastic systems, which makes it possible to increase reliability of temporary isolation of aquifers. The paper presents an analysis of domestic and foreign experience of blocking permeable formations by different mixtures. Three-phase blocking mixtures are studied and requirements for them are generalized.
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Abstract
The paper considers simulation of well test processes with application of packers. Based on well parameters at different times (before a well is closed and the point in time under consideration) a mathematical model is compiled. Superposition principles are used for constructing points of pressure recovery curve. Based on that, four cases of using packers are considered according to actual pressure diagrams. Processing of build-up curves helps to determine other characteristics of a formation as well. Since a bottom hole zone is broken in a number of cases and its permeability is reduced, an amount of reservoir contamination indicators is defined as an additional pressure drawdown that has to be created to overcome resistance of reduced permeability zone. It should be noted that existing works related to assessment of influence of after-inflow effect relate to either determination of its duration or adjustment of pressure build up curves by introducing correction factors. To overcome a challenge of pressure build-up taking into account an effect of pressure drop and after-inflow effect an approximate method to solve problems of nonstationary flow is used. The method of integral relations allows obtaining solutions in a simple analytical form. After a well is closed, conditions for redistribution of pressure in bottom hole area are changing. At remote sections of a formation the process continues to flow without changing as during the functioning of a well. Therefore, it is supposed that pressure wave continues to propagate according to the Says-Horner law. As it was determined during modeling of various penetration conditions, pressure distribution curves in bottom hole area have clear straight horizontal sections after well closure. The length of sections increases with the increase of bottom hole pressure. If the cause and nature of build-up curves are known full information about pressure change after well shut will be used. So, it will help to determine parameters of distant and bottom hole area of reservoir more accurately.
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Abstract
The purpose of the work is to study influence of friction between samples and press plates on mechanical parameters of salt rocks. The main source of information for determining values of mechanical parameters of salt rocks is laboratory tests of rock samples for compression. It is known that values of mechanical parameters determined from results of compression of samples essentially depend on magnitude of frictional force between fronts and plates of a press. Wherein, empirical coefficients of shape used in calculation of values of mechanical parameters corresponding to uniaxial compression do not take into account specific frontal conditions. This leads to a known inaccuracy in formulation of an experiment and interpretation of its results. Thus, relevant studies correspond to more detailed study of influence of friction between samples and press plates on mechanical properties of salt rocks. During experimental studies 75 samples of fine to medium grained rock salt from Verkhnekamsk deposit of potassium salts were tested. The paper presents results of experimental studies directed to determine coefficient of friction of salt rocks according to a scheme "shear with compression" over various surfaces. Studies were carried out on compression of samples of different heights under known contact conditions. The necessary friction value was modeled using manufactured gaskets placed between fronts of samples to be tested for compression and press plates. A full diagram of deformation was build from the compression results of each sample and a set of mechanical parameters was determined. Dependences that reflect an effect of frictional forces between fronts of samples and press plates under compression on values of strength limit, destructive deformation and specific energy consumption of rock salt deformation are determined. Results of the study are intended to improve a method of testing rocks for compression.
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Abstract
The purpose of the paper is experimental study and description of mechanism of magnetic and hydrodynamic (MHD) activation of oil for protection from wax deposition and to increase efficiency of heavy oil production. A brief review of history of magnetic activation (MA) application is performed. Laboratory methods used to record efficiency of MA are described. As a result of experiments several points were established. Firstly, a positive effect of protection from wax deposition is implemented for all types of oil, regardless composition and viscosity, but it is necessary to select individual activation regimes. Secondly, it is shown that magnitude of the "magnetic memory" of oil increases nonlinearly with increase of magnetic field strength and can reach 20-40 hours. Thirdly, a common resonance mechanism for MA of oil is established. Fourthly, a magnitude of MHD activation effectiveness is determined by content of asphaltene and resin matter, that is dispersed oil phase. A brief theory of spin dynamics of paramagnetic radical pairs which takes place when oil is activated is described. The mechanism of MHD activation is as follows: a magnetic field with a small amount of excitation energy in capacity selects chemical and physical reactions by controlling spin state of electrons and stimulates recombination and birth of paramagnetic radical pairs. That ensures appearance of long-term high-energy activity (phase transitions) of asphaltene molecules with emission or input of energy, leading to structural rearrangement of nuclei of asphaltene structures and physical macroparameters of oil as a whole. Wherein, the positive protective effect against wax deposition after MA is caused by aggregation and enlargement of asphaltene complexes, a decrease in specific adsorption surface of paraffin crystals and creation of harmonic vibration modes in oil matter, which reduce a probability of nucleation and subsequent growth of paraffin crystals. Obtained results can be used in development of modern methods for controlling the properties of oil dispersed systems and development of downhole and ground surface MHD activators.
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Abstract
The paper gives an analysis of implementation of hydropneumatic accumulators that provide significant reduce of energy consumption work processes and increase performance of mining machines, in particular cone crushers. A method that allows passing a body that is not to be crushed through a crushing chamber of a cone crusher with hydraulic cylinders and hydropneumatic accumulators is given. The system that presses crushing bowl to a frame is described. A system of hydraulic unloading from non-crushing bodies and blockages is presented. A basic hydraulic scheme of pressing system is proposed. The paper gives a description of mechanism that creates work pressure inside hydropneumatic accumulator. Parameters of hydraulic cylinders and hydraulic accumulators are determined. The crushing force is set by dimensions of hydraulic cylinders and pressure of work fluid in hydropneumatic accumulator. When a non-breaking body enters a crushing chamber a movable cone moves an armor of a bowl with support and control rings and associated elements. An example of calculation is given. Calculations are necessary to design a new hydraulic unit that control discharge slot of a cone crusher. A method for determination of geometric parameters of crushing chamber when passing a non-crushing body is given. Calculation of power parameters of hydraulic system of a cone crusher including hydraulic cylinders and hydropneumatic accumulators is proposed. The method can be applied in design departments of mining and industrial enterprises while design of cone crushers. A proposed hydraulic scheme with throttle installation will reduce speed of fluid flow when unloading a hydraulic accumulator. That will reduce impact of accumulator piston and foaming of liquid in a tank.
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Abstract
Today mining is developing very intensively and potash industry in particular. Reserve areas are explored and cut, new fields are explored and developed, new license areas of potassium and magnesium deposits are developed. Underground mining of mineral deposits leads to significant deformation of the earth's surface. The impact of potash industry on the environment is diverse and covers many natural components. In case of mine flooding, catastrophic consequences, accompanied by depressions and sinkholes, cover a considerable area. The main feature of potash production is accumulation of a significant amount of waste in sludge storage and salt piles with brine collectors. Sewage and penetration from salt piles and sludge storage are the main sources of environmental pollution. Mining and processing of ore at potash enterprises is associated with formation of a large number of waste rocks. Millions of tons of liquid and solid wastes are stored on ground surface in salt piles and brine sludge storages, which negatively affects the environment. However, negative effects of salt pile placement can be avoided or minimized. Today there are a number of developments aimed to improve methods of underground storage of wastes of potash industry both solid halite and liquid clay-salt. The paper considers a new version of waste disposal placement of potash industry, which is currently being considered in design documentation for development of licensed area of Nivenskoe-1 field of potassium and magnesium salts in Kaliningrad region. In case of a positive conclusion of state expertise, this technology will be implemented. Such approach could be used in development of other deposits of potassium and magnesium salts (Verkhnekamsk, Gremiachinsk etc.).
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Abstract
The value of resistivity of a grounding device depends on specific electrical resistance of ground, therefore, when designing grounding devices it is necessary to take into account layered structure of ground. The paper presents results of a study of influence of the main ground properties such as ground structure and composition, temperature and humidity, that depend on climatic and weather conditions of terrain and season, ground porosity, presence of salts, alkaline and acid residues, depth of occurrence of groundwater by the value of their specific electrical resistances. On example of ground structure of northern and southern areas of Perm region, effectiveness of a method for calculating grounders over the upper and lower layers of ground is shown. The results of calculations in a form of graphical functions of resistance of a vertical grounding device versus its length in a multilayered ground are given. For northern areas of Perm region the use of simplified techniques in calculation of grounding devices only over the upper layer of ground leads to significant deviations in calculated values from the actual ones. The effect of climatic conditions on specific electrical resistance of ground is analyzed. The results of study of influence of rock porosity on specific electrical resistance of ground are presented in example of such rocks as sand, sandstone and limestone. It is shown that specific electrical resistance varies depending on different values of ground porosity in wide ranges: at high values of ground porosity its specific electrical resistance decreases sharply due to the fact that pores can be filled with liquid while increasing conductivity of ground. Thus, this paper substantiates a thesis about the need to take into account basic properties of ground such as stratification, seasonal climate coefficient and porosity, when designing grounding devices of electrical units to ensure safe electrical conditions. In addition, it is shown that considering heterogeneity of the earth greatly improves accuracy of calculation of grounding devices and reduces cost of their design.
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