Vol 19, No 2 (2019)
- Year: 2019
- Articles: 8
- URL: https://ered.pstu.ru/index.php/geo/issue/view/92
Abstract
A model of multi-stage formation of the Visean oil deposits of the Solikamsk Depression under conditions of ancient oil-water contacts stabilization is proposed. With long-term presence of reservoirs in the conditions of oil-water zones, there is an active development of oxidative processes, as a result of which the oil-saturated reservoirs undergo irreversible changes in rock wettability. After the arrival of new portions of hydrocarbons and the formation of a modern oil-water contact, the residual products of oil oxidation form solid bitumen. The cases of lack of bituminous reservoirs in the intervals of ancient oil-water contacts are explained by active fluid exchange of reservoirs. It has been substantiated that high specific electrical resistances (SER) of terrigenous reservoirs of the Visean deposits of the Solikamsk Depression, exceeding 600 Ohm∙m, are associated with their hydrophobization under the conditions of ancient oil-water contacts. The results of electrical side logging are compared with the assessment of the rock wettability using core X-ray tomography and microscopic analysis of thin sections. A statistically significant excess of rock porosity in comparison with a standard geophysical section has been established for Visean high-resistance reservoirs of the Shershnevskoye field. For intervals with a resistivity of < 120 Ohm m, the maximum distribution of porosity is observed in the range from 12 to 16 %. In the high resistance section for resistivity intervals from 200 to 600 ohm∙m, the highest frequency of porosity is set in the range of 16-18 %; for resistivity > 600 ohm m - with porosity of more than 18 %. On average, the porosity excess in the high resistivity section is more than 3 %, which is probably due to the predominance at the levels of ancient OWC processes of collectors decompaction (dissolution) over their cementation. For the Visean operational objects of the Shershnevskoye field, a geological model was constructed according to the SER values, highlighting zones (volumes) of reservoir development of various wettability types. In general, the established zones have a regular spatial arrangement.
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Abstract
The physicochemical properties of clays depend on the group of factors that determine the energy potential on the surface of the particles, and on the factors that form the specific surface of the particles. The formation of the specific surface of the particles is directly related to the issues of microaggregates formation in soils. The study of the pressure effect on the aggregates formation in dispersed soils showed that at pressures up to 200 MPa, there is a slight change in the aggregate composition of wet soils. With a pressure of 300 MPa of silty soil, the content of fine sand fraction increased from 13 to 51 %, silt - from 5 to 23 %, and clay - from 2.15 to 5.42 %. When testing cover loam with pressure P = 2000 MPa and P = 3660 MPa, similar results were obtained. It can be seen from the above that the issues of the pressure influence on the microaggregate formation composition and, as a consequence, the physicochemical properties of clays are of considerable interest. Therefore, the aim of the work is to study the patterns of changes in the composition of clays exposed to high pressures. As a result of experimental studies, it was found that with increasing pressure, there is a general tendency for a decrease in the clay content and an increase in the dust fraction. Along with this pattern, in each class, local changes in the content of the fractional composition of clays depending on pressure were revealed. With increasing pressure, the specific surface area of kaolin and montmorillonite clay particles decreases. Changes in the particle size distribution are due to the processes of aggregation and dispersion of particles. In the process of aggregation caused by high pressure, coagulation, transitional and phase contacts between particles are formed. The crushing and propping pressure of a film of bound water around particles are the leading factors determining the process of their dispersion.
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Abstract
The article presents the comprehensive results of petrophysical studies of rock samples taken from exploratory wells across the area of the Hamamdag-Deniz field, where Pliocene formations are widely distributed. The choice of the object of research is connected with the fact that in the indicated deposit in the interval of existence of the Pliocene formations some deterioration of porosity and permeability deviates from the traditionally predicted and at fairly great depths the primary porosity can be maintained, or will appeared a secondary reservoir productivity. Thus, studies have shown that the physical characteristics of rocks of the same age and the same type may differ in the process of lithogenesis and due to the influence of geological and geophysical factors. Here were studied also the reservoir properties of sedimentary rocks of Pliocene age. The obtained data are tabulated, reflecting the variation of the physical properties of various types of reservoir rocks and the pattern of their change in area and depth, taking into account the geological features of the cross-section. In addition, the average values of the granulometric composition of the rocks in depth along the entire section of the above area were analyzed. It was revealed that at small depths (835-1088 m) the fractional composition of rocks favors high porosity (max 26.6 %) and is accompanied by a high propagation speed of ultrasonic waves (3000 m/s) and density (2.28 g/cm3). At medium depths (3669 m) where aleurolite is dominance (69.6 %), the maximum porosity of the reservoirs rocks is 20.0 %, and the permeability is 32.6·10-15 m2, which may be due to good sorting and weak compaction of grains (this is indicated by low density and speed of ultrasonic waves). Further, at great depths (4439 m) there are sandy-clayey siltstones with a content of 53.3 % aleurite, 21.9 % sand, 36.1 % clay and a carbonate of 19.9 %. Here, the porosity is lower (max 21.3 %), but the permeability of rocks is 129.0·10-15 m2, which indicates a relatively low sorting and higher density of these sediments. This is also indicated by the high speed of ultrasonic waves within the considered depths. In addition, the article reviewed the issues of dependence of permeability on porosity, and porosity on depth.
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Abstract
The aim of the work is to increase the efficiency of opening of productive layers when using drilling fluids on a hydrocarbon basis. In this paper, several studies have been conducted: assessment of the effect of the content of the aqueous phase on the change in the rheological parameters of solutions; assessment of the gilsonite type influence on the structural-rheological and filtration parameters of the hydrocarbon-based solution. Completion of wells with the use of hydrocarbon-based solutions is most appropriate in order to preserve the reservoir properties of the reservoir, however, such solutions are quite expensive. In order to reduce the cost of such systems, emulsion solutions have been developed, which are increasingly being used during the initial dissection, but for their effective use it is necessary to reasonably choose the component composition, since even small fluctuations in the number of reagents responsible for the stability of the system can lead to emulsion coalescence and separation phases. Opening the formations with an emulsion solution can lead to many complications, all of which reduce the connection of the reservoir with the wellbore or reduce the permeability of the formation. One of these complications is the loss of drilling fluid circulation. The solution used for the opening of the reservoir should be a solution that is designed to practically not impair the natural permeability of the production zones and to provide excellent washing of the barrel and easy to clean. There are various materials, such as gilsonite (natural asphalt) or bitumen, and amine-treated lignin, as well as polymeric fillers used to prevent takeovers by reducing filtration and forming an impermeable filter cake. Studies conducted in the work have shown the effectiveness of natural and synthetic asphalt in the systems of the precautionary zone, as well as opened the field for further research in order to identify patterns that occur when changing the component composition.
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Abstract
One of the types of complications arising from the construction of a significant number of wells in the Denisovsky depression of the Timan-Pechersk oil and gas province is the loss of stability of the bore walls in the “reactive” clays of the Kazan and Tatar layers of the Perm system. With the use of X-ray phase, X-ray fluorescent and lithologic and mineralogical analyzes, a complex lithological characteristic of landslide rocks of the specified drilling intervals is presented. As a result of the study, the features of the mineral and chemical rock composition and their clay component were determined. The results obtained in the course of conducting a diverse complex of studies of drilling fluids inhibiting properties, including the following types of tests: the study of the rock swelling degree; test to determine the shale erosion in drilling fluids environment; assessment of drilling fluids dispersing ability; test for the formation of cracks in rock samples in drilling fluids environment; study of the nature and intensity of the ion-exchange processes in the system “rock - drilling fluid”; study of changes in the physical and mechanical properties of rocks after exposure to drilling fluids are considered. According to the results of the research, the gradation of various types of drilling fluids according to the inhibitory ability with respect to swelling clay rocks was proposed.
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Abstract
Currently, there are many packages of interpretation of data of geophysical studies of wells, allowing to solve geological problems and to monitor the technical condition of wells. To assess the state of wells using a set of methods, including acoustic, radioactive, electromagnetic, etc. The article presents a comparative analysis of the capabilities of existing well logging packages to control the technical condition of wells. Both packages of other companies and own development - modular system of processing and interpretation of well logging data (“Sonata”) are analyzed in detail. The possibilities of programs at all stages of processing and interpretation are considered: support for various data formats, assessment of material quality in accordance with industry standards, support for step-by-step processing, pre-processing, determination of signal parameters, calculation of physical and mechanical properties and other parameters, data processing of various acoustic, radioactive, electromagnetic methods and profile measurement. The advantages of the “Sonata” system in comparison with the existing software systems are shown. The article analyzes the internals of a system “Sonata” and service software packages accompanying the specified software system. The most important features of the software architecture of the Sonata system are presented: object and component models reflecting the internal structure of the interpretation complex. From the accompanying programs, compression packages of well geophysical data, their evolution and algorithms developed for compression are analyzed in detail. Many years of experience in the use of a modular system of processing and interpretation of data of geophysical studies of wells “Sonata” in geophysical organizations of Russia showed that the system is in demand in oil service organizations, allowing to solve a full range of problems of monitoring the technical condition of wells, providing an ergonomic interface and a convenient set of tools for the formation of final conclusions and documents.
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Abstract
Almost all oil fields to maintain reservoir pressure produced water injection. In case of significant layer-by-layer heterogeneity, water from injection wells will begin to flow through the channels with low filtration resistance into the production wells. At the bottom of the injection wells, pressures are created that substantially exceed reservoir pressures. The most intensively the movement of the injected water from the injection to the producing well manifests itself in deposits with high-viscosity oil. When watering production wells are working on waterproofing and alignment of the injectivity profiles. To estimate the time of approach of water from a producing well to an injection, a series of mathematical experiments were performed on the Tempest More software complex to predict the movement of the displacement front in a reservoir with different viscosities of reservoir oil, reservoir permeability, bottomhole pressures in the injection and production wells. Fluid properties and relative phase permeability were used from the Nozhovskaya group of deposits (Perm region). According to the results of the generalization of the simulation results, an equation was obtained for estimating the timing of the advance of the displacement front along the collector. Analyzing the results of the calculations, it can be concluded that the mobility coefficient influences the time of the displacement front moving for a certain distance exponentially. In reservoirs with a mobility of more than 2 mkm2 / (Pa ∙ s), the water-oil front moves at a speed of about 1 m/day. Comparison of the predicted values of the time of irrigation of producing wells for the reservoir with high-viscosity oil, performed using hydrodynamic modeling and the developed equation, shows a fairly high convergence of the results. Using the equation will allow you to pre-plan measures for the water insulation of wells and the alignment of injectivity profiles.
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Abstract
At present, the coal industry in Russia is demonstrating an increase in coal production against the background of increasing exports of minerals. Coal mining on the territory of the Russian Federation is made by open and underground methods, currently there are 59 underground mines and 108 coal mines operating. The peculiarity of the modern stage of development of mining at a quarry is the high concentration and intensification of all technological processes associated with the extraction and processing of mining raw materials. The above is accompanied by the increasing complexity of the process of airing the open pit space, the deterioration of working conditions due to dust and gas factors, and the negative impact on the human body and the environment. Why is coal dust so dangerous? According to research data, when dust is received in excess of 58 kg / ha per month, there is an effect of depressing the vital activity of most plants and animals in the area. Inhaled dust causes acute diseases of the upper respiratory tract. The accumulation of dust explosive and combustible materials in the air threatens to explode or ignite. The increased amount of dust adversely affects the condition of the equipment. In addition to purely mechanical wear due to the ingress of abrasive particles into moving parts, malfunction of the machine control systems is possible, since an increased amount of dust gets into the electronic control units. The resource of engines operating in dusty conditions is reduced by 2-3 times. The impact of dust increases the intensity of the corrosion process, maintenance and repair of equipment become more difficult and longer in time. Therefore, the suppression of dust - an extremely important event, which is used in many industries. Dust suppression is a very broad concept. This article covers only part of this issue - a set of ways and means. To combat dust, a variety of methods and equipment are used - from complex stationary exhaust ventilation systems, cyclone separators and electrostatic dust collectors to sprinklers, hydromonitors and fogging guns that spray water, chemicals and foam. This article analyzes the specifics of mining in negative temperatures, sources of dust formation, the effect of dust on the human body and dust suppression methods that are used on coal mines in general, and also deals with the problem of dust suppression on coal mines of the Far North. This problem is relevant today, as many coal-mining enterprises in Russia operate in low temperature conditions.
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