Vol 17, No 1 (2018)
- Year: 2018
- Articles: 8
- URL: https://ered.pstu.ru/index.php/geo/issue/view/101
Abstract
The necessity to apply probabilistic and statistical methods for evaluation of oil and gas potential of small-size local structures is substantiated. The existing large amount of geological and geophysical data on the characteristics of structures is a good basis to use probabilistic and statistical methods to forecast their oil and gas potential. The paper presents a methodology for predicting the oil and gas potential of local structures by probabilistic and statistical methods on the Pozhvinskiy sector for Tl2-b and Bb reservoirs. Geological and geophysical parameters that control the oil and gas potential of local structures are analyzed. Those parameters are as follows: altitudes on the roof of layers Tl2-b, Bb, net oil-bearing thickness of Tl2-b, Bb, net reservoir thickness Tl2-b, Bb, interval time between reflecting layers 2K-2P - d T 2K-2P, interval velocities between layers 2K-2P - V 2K-2P, interval time between reflecting layers 3-2K - d T 3-2K, interval velocities between layers 3-2K. Informativeness of each parameter was determined on reference sectors with determined oil and gas potential and sectors that have deep wells but oil and gas potential is unknown. To solve the prediction problems, it is necessary to comprehensively take into account all the considered informative parameters considering the contribution of each parameter to the final result. The complex P com criterion which estimates the oil and gas potential for a set of parameters was used for that purposes. Oil and gas content is evaluated by the developed method over the entire study area by constructing maps of equal probabilities. Minimum, maximum and average P com values for Tl2-b and Bb reservoirs are calculated within the contours of local structures. The work resulted in an evaluation of the oil and gas potential of the structures for Tl2-b and Bb reservoirs. As a result of analysis, it is established that Bezgodovskaya and Ryabovskaya b structures within the Pozhvinskiy sector are the most promising ones in terms of oil and gas potential.
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Abstract
Reservoir properties of carbonate rocks of the Triassic deposits are considered. The rocks have the most importance for Southern Mangistau in terms of oil and gas potential. According to the lithological composition there are two types of reservoirs in the Triassic sediments determined such as clastic and carbonate. Carbonate reservoirs are localized in the tuffaceous-dolomite and tuffaceous-calcareous strata of the Middle Triassic period. Those rocks are characterized by a complex type of reservoir and represented by porous-fractured, porous-cavernous and fractured rocks. The carbonate matter in reservoirs of the Middle Triassic period is lithologically nonuniform. There are micro-grained and oolitic dolomites and their hybrids with limestones, clays and silicites among them. The cavernous nature of carbonate rocks and reason for their formation are studied. The largest number of caverns was recorded in clayey and siliceous dolomites and dolomitized oolitic limestones. There are intervals of development of cavernous-porous rocks detected in the sections of the Middle Triassic period fields of Northern Karagie, Ala-Tyube and in the areas of Tarly-Kuyjak and Kamenistaya as well. As a result of microscopic studies, it is established that the storage capacity in that rocks is formed due to caverns and primary intergranular pores. Storage capacity of oolitic dolomites, oolitic, pseudo-oolitic limestones, organogenic detritus limestones was increased under significant influence of leaching processes at the stage of catagenesis under the action of circulating chloralkalic or chloromagnesium waters. It is established that the main part of the storage capacity of porous-cavernous rocks consists of caverns, which size reaches 5-6 mm. According to reservoir properties and structure of the void space, the cavernous-porous rocks of the productive Triassic sequence refer to the cavernous-porous reservoir. There are two genetic types of micro fractures in the pelitomorphic limestones in the areas of Akkar and Kamenistaya such as post sedimentation and tectonic. It is established that for carbonate reservoirs of the volcanic-dolomitic sequence fracture permeability is the main component of the total permeability.
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Abstract
Today, the problem of production of surplus associated water is particularly actual because of transition of fields to the final stages of development. Water shut-off works are the main method to combat the increased water cut of wells of modern fields. One of the most important stages in water shut-off works is the selection of candidate wells and determination of their sources of water inflow which depend on the geological structure of an oil reservoir and well technical state. Technical reasons of water inflow to wells include leakage of a production string and annular circulation. Geological reasons include lift of water-oil contact to the bottom hole, breakthrough of water along the productive formation, fractures between wells or formations. The article discusses production wells of the Visean reservoir of the Perm region field with shut-off works done. Wells are divided according to the most common sources of water inflow into two groups such as a breakthrough in the productive formation of pumped or aquifer water. To analyze the average values of geological and technological parameters of the two groups of wells obtained from the field data the Student's t -criterion is used. Among the analyzed parameters the distance from the lower perforation to the water-oil contact, formation thickness and thickness of the interval of water inflow are statistically significant. To determine the sources of water inflow for 19 candidate wells of the Visean reservoir of the Perm region field a discriminant analysis is performed. Based on the table of values of a posteriori probabilities, it is revealed that 4 wells of 19 candidate wells for water shut-off works are flooded due to breakthroughs of pumped water through the productive formation, 4 wells are flooded by aquifer water. The 11 remaining candidate wells are likely to have another source of water.
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Abstract
The main factors affecting the efficiency of proppant hydraulic fracturing of Tl-Bb clastic reservoir depending on various parameters are statistically studied. There are 36 hydraulic fracturing treatments pumped from 2008 to 2016 with an average increase in oil production rate of 8.6 tons per day. Probabilistic statistical models were built to determine the parameters that influence the effectiveness of hydraulic fracturing. The average annual increase in oil production is used as a dependent variable; geological, technological and technical parameters are used as independent variables. To determine the degree of impact of parameters wells are divided into two classes of effectiveness: Q o > 8 tons/day (class 1), Q o < 8 tons/day (class 2). For the first class of each parameter individual statistical models are built for prediction and its probability is calculated. For the combined use of individual models complex probability is calculated separately for geological technological and technical indicators. As a result, regression models are built using step-by-step regression analysis. The standard error of the model for geological and technological parameters is 2.0 tons/day and 2.2 tons/day for technical. The joint consideration of geological technological and technical parameters in the regression model reduces the standard error to 1.5 tons/day. It is concluded that a separate description of the processes of hydraulic fracturing allows evaluating the efficiency of hydraulic fracturing in specific geological and technological conditions at the design stage, based on the use of developed individual models. After the hydraulic fracturing performed using the developed models considering technical conditions it is possible to preliminary estimate the effectiveness of hydraulic fracturing. The developed methodology for predicting the efficiency of hydraulic fracturing, performed on the Tl-Bb reservoir, is recommended to be used at other reservoirs of the field after correction of the built models. On the other fields where information for building the probabilistic and statistical models is available, it is necessary to develop new probabilistic and statistical models.
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Abstract
The paper presents results of the study of processes of coal dust detonation combustion obtained using a technique approved by the authors. The essence of the technique is the use of a specific coal dust fraction to study the explosion pressure, explosion pressure increase rate and transformation coefficient. It allows applying the results of a laboratory experiment to the actual data of explosion and combustion of dust and gas mixtures of mines that have a much larger volume. In other words it allows predicting the explosion pressure increase rate in relation to specific excavation of coal mines. The methodology for studying combustion and detonation processes, briefly described in the article, is based both on requirements of modern regulatory documents and the practical experience of research institutes engaged in similar research. The practical component of the method is based on an installation which represents an explosive combustion chamber in the form of a sphere with a volume of 20 liters. The data of detonation combustion are processed using application software and presented graphically in three figures. It is shown that dispersion composition of coal dust indluences on the explosion pressure, explosion pressure increase rate and transformation coefficient. Research work is carried out with a sample of coal of KS-type from a thick beam of the mine named after Dzerzhinskiy. As a result of the analysis of digital and graphic data obtained during processing, it is proved that dust with fractional composition of 63-94 μm is the most explosive. It is revealed that explosion pressure increase rate changes as a function of dust concentration in the installation reaction volume in the way that there was two maxima of the explosion pressure increase rate where one was at 100 g/m3 and the second at 400 g/m3. The results obtained during determination of the explosion pressure increase rate have shown the necessity of a non-trivial, more thoroughtful approach to study explosion pressure increase and, consequently, determin the transformation coefficient. In addition, analysis of the experimental data presented in the article confirmed that during the development of means of flame retardation and explosion suppression used in automatic means for explosion localization it is necessary to carry out further investigations with the coal dust fraction equal to 63-94 μm. The results obtained in the work will allow starting the study of the processes of detonation combustion in a dusty air containing methane.
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Abstract
Modern working conditions of miners in the mining industry are characterized by intensive noise and vibration, high dustiness, unfavorable microclimate, the levels of which often exceed hygienic standards. Unfortunately, the current regulatory framework does not take into account the fact that in real life most of the production personnel are exposed not to one but several factors of the working environment at the same time. Thus, the sanitary standarts established for factors that act singularly and guarant the preservation of health precisely for these conditions may be untenable. Ensuring sustainable safety when working in electrical installations should be achieved by complying with electrical safety requirements. But permissible levels of contact currents and voltages currently recommended by the International Electrotechnical Commission do not take into account the joint effect of electric current and other physical factors, and noise in particular. The effect of sound pressure level and its frequency on the resistance of the human body is proved earlier in V.V. Katsay's thesis. The study of the effect of noise on magnitude of threshold perceptible current is resumed in laboratory conditions at the Department of Life Safety of the South Ural State University. To obtain reliable results a test complex was designed and built. The complex includes a muffled chamber, sources of simulated voltages and noise, a block of recording instruments. Primary electrical safety criteria are investigated for an increased frequency (5000 Hz) under the influence of noise load. Voltages and currents that cause feelings are measured before the impact of noise and under the influence of noise with a sound pressure level of 97 dB. The dependence built calls into question the result obtained from results of previous studies on the need to reduce settings at which tools of safety shutdown trigger.
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Abstract
The methodology of investigating the dispersion composition of mine dust is presented. The methodology is based on modern science-intensive methods such as the method of scanning microscopy and simple methods such as the method of sieve granulometric analysis. Today, the granulometric analysis is given great attention aimed to study the dimensions and aerodynamic characteristics of mine dust particles. The methods are applied separately from each other. Therefore, the paper discusses the most popular science methods gives recommendations on their joint application on the basis of the author's research on the dispersion composition of mine dust. Methods of scanning ectronic and optical microscopy are briefly described. Laser diffraction and sieve granulometric analyzes used to study the composition of coal mine dust are considered. That is chosen to use mine coal dust collected from the surface of hydraulic support racks of cleaning faces and coal dust obtained by the method of forced grinding of hard coal samples of different grades and anthracite as the samples for study. Samples of coal are taken from the working space of the mines of the Pechora, Kuznetsk and Donbass coal basins. Based on a comprehensive study of methods and analysis of results of studying the dispersion composition, their main advantages and disadvantages are given. The research methodology is based on physical methods for studying the dispersion characteristics of mine dust. In connection with the fact that one or another method is implemented in one device (installation), then in order to obtain complex data it is proposed to combine them into knowledge-intensive pairs. The combination in pairs of the equipment allows to study thoroughly both the dispersion composition and morphology of the dust particles, including the surface structure of dust particles if such a task is posed. Selection of samples and processes of preparing samples for research are in the basis of all methods used for obtaining qualitative and reliable scientific results. As a result of the experimental work carried out to prevent endogenous fires and explosions in the coal mine area, the author proposes to use a comprehensive approach consisting in applying synchronous thermal analysis methods together with methods for studying the dispersion composition of coal dust.
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Abstract
The purpose of the paper is to substantiate the approach to determining the required probability of detecting unauthorized attempts to contact the pipe shell to maintain a minimum level of pipeline security losses. That is also nesseccerly to assess probability trend in the near future. Based on the information obtained it is planned to propose the structure of the physical pipeline security system to neutralize terroristic attacks. Results of studies of vibroacoustic oscillations in the shell of a major pipeline during its operation are given. The mechanisms of change in parameters of a vibroacoustic pulse excited at a local point of a pipeline when it is propagated through a pipeline are expalined. Results of studies on the solution of the problem of detection and prevention of emergencies in the protected zone by seismic oscillations are considered. It is concluded that it is possible to detect precursors of emergencies by vibroacoustic and seismic vibrations of the pipe shell. The effectiveness of the proposed approach to determine the requirements for systems of protection of objects from terroristic threats is demonstrated. The region was chosen in accordance with available published data for a relatively long period of time, necessary for setting up a computational experiment. It is interesting to receive prognostic estimates in that segment of economy for the country as a whole. Presence of such information allow creating a policy for detecting terroristic attacks and deciding on the requirements for the physical protection system that have to be provided in the current period and short term. Today, there is no way to effectively fight with prepared violators to achieve their goals using any of the known single-sensor systems. It is concluded that there is a need to develop a multi-sensor system, minimum equipment of which should include interconnected seismic and vibro-acoustic subsystems. Combination of vibro-acoustic and seismoanalytical subsystems allows compensating the most significant drawbacks of each of them.
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