Vol 19, No 4 (2019)
- Year: 2019
- Articles: 7
- URL: https://ered.pstu.ru/index.php/geo/issue/view/120
Abstract
The problems of the structure of the Upper Devonian rifogenic deposits within the Moroshkinsky, Ust-Tsilemsky and Severo-Tebuksky reference areas located on the territory of the Komi Republic and the Nenets Autonomous District are considered. Based on the reinterpretation of the materials of wells geophysical research with the use of a core lithological description and results of its laboratory studies, the structure of the Domanik-Famennian part of the section is detailed, the correlation scheme of deep wells sections is presented. As a result of section correlation, some stratigraphic boundaries were corrected, the volume of lithological-stratigraphic units was determined, reference packs well displayed on geophysical diagrams, and traceable carbonate formations known to geologists as F1, F2, F3, F4, F5, as well as interstratal packs were identified. This paper presents the results of geochemical studies of the Upper Devonian rifogenic deposits of wells drilled on the territory of the Moroshkinsky, Ust-Tsilemsky and Severo-Tebuksky areas. The distribution of the organic carbon, chloroform and alcohol-benzene bitumoids content in the rocks of individual well horizons is presented, and the oil and gas potential of rocks is characterized by pyrolytic data. Based on a comprehensive analysis of the laboratory and analytical core studies results and materials from geophysical surveys, reservoirs were identified, their quantitative parameters and the nature of saturation were evaluated. The criterion for assessing the reservoir properties of rocks was the porosity coefficient. The determination of porosity by neutron gamma-ray logging was carried out using the method of two support layers using the dependencies of KamNIIKIGS JSC. To assess the quantitative parameters of carbonate reservoirs, the results of standard core studies were used: open porosity, absolute gas permeability, bulk density. The results of the research can be used when conducting exploration in the territory of three considered reference areas.
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Abstract
Assessment of oil recovery coefficients based on geological and hydrodynamic modeling requires large financial and time costs. As a result, recalculations of recoverable hydrocarbon reserves are carried out after a long time and are not adjusted within significant time intervals. Approved oil recovery factors can significantly lose relevance due to changes in the economic conditions of development or the discrepancy between the actual conditions of development and design. For a reliable assessment of the residual recoverable reserves of oil production objects, it is extremely important to quickly monitor the validity of the oil recovery factors, including its objective attainability in specific time frames. The article analyzes the practice of conducting annual geological and economic reserves assessment according to the international standard using the example of oil fields in the Perm region. The conclusion is drawn on the need for a similar control of recoverable oil reserves, calculated according to the Russian classification. Several areas of operational monitoring of the approved oil recovery coefficients assessment are known: the use of analog-statistical methods, displacement characteristics, and analysis of the production decline rate. The methods are based on various physical laws; their effectiveness largely depends on the quality of the initial information and the stage of development of the production objects, on economic conditions. Using specific examples, the effectiveness of approved oil recovery factors control is considered. For the early stages of development, the most effective is the use of multidimensional analog-statistical dependencies based on geological indicators built for specific operational facilities. A long period of deposits development in the Perm Krai and a sufficiently large number of objects located in the late stages of development allow us to implement such a statistical approach. In the late stages, methods based on the displacement characteristics and the oil production decline rate take on greater reliability, taking into account the economic limit of development profitability. As a control, statistical dependencies can be used involving not only geological, but also technological indicators. The integrated use of various methodological approaches allows a more reliable assessment of the residual recoverable reserves of production objects.
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Abstract
The features of the design and technology of drilling wells for thermal waters are considered. The practice of prospecting, exploration and production of thermal waters in the difficult mining and geological conditions of Central Mongolia and analysis of the previously drilled wells results have established that the accepted and implemented design and technology for drilling hydrogeological wells does not provide reliable protection for the drilled thermals from cooling when water flows from them along wellbore from the bottom to the wellhead. The reason for this is significant heat loss due to the high thermal diffusivity of the well structural elements (steel pipes). A promising well design has been developed and is proposed, including several successively deflated casing strings with mandatory cementing of the annulus with grouting. At the same time, the total heat loss is reduced, and the temperature at the wellhead rises by 10-15 degrees. It is also proposed to use double-walled casing strings (“pipe in pipe” technology), in the annular space of which there is a heat-insulating material - polyurethane foam. Using this technology will reduce heat loss in the wellbore by 20-30 %. For drilling in this region, it is advisable to use pneumatic and hydraulic hammers to drill the pilot shaft with its further expansion with a cone bit. Drilling rig can be URB-2A-2. Successful search and exploration of thermal waters in Mongolia is an extremely promising and important goal. The technology of cementing the well with pipes using polyurethane foam will reduce heat loss along the wellbore by 20-30 %, which will provide the possibility of obtaining a water temperature at the wellhead that is as close as possible to the formation. The proposed design of the hydrogeological well increases the economic effect.
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Abstract
The article presents the results of data analysis for the construction of a geological model of the Verkhnekamskoye Deposit of potassium - magnesium salts in the mines of the Solikamsk site. It is assumed that the development of the model will calculate the expected volume of host rocks in the planning of mining, set in the vertical plane of the position of the combine relative to the roof of the formation at the intersection of folds. The strength characteristics of the layers obtained from the model should be the input data for the calculation of the development parameters in the planning of mining operations. The simulation results are used to assess the expected risks in the process of mine development, and in solving many other problems. Primary information on deep wells and wells drilled from mine workings is not enough to build a reliable model to help solve the previously listed and many other problems. The authors have developed software modules for the geological service, allowing to replenish the database with a vector image of the boundaries of the layers and layers of the preparatory and cleaning workings. The modules are based on processing field geological sketches for both scanner and digitizer technology. In the developed programs, standardized reference books of breeds and accepted stratigraphic division of the stratum are sewn up. The use of such information will significantly clarify and detail the model in the strata of industrial formations. It has been established that the variability of hypsometry of industrial seams is an order of magnitude greater than the variability of their thickness. A significant difference in power and altitude fluctuations will affect the model construction technique. The program modules developed for geologists are integrated into the corporate mountain-geological information system of PJSC Uralkali. This system is created on the initiative and with the direct participation of the authors.
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Abstract
Carbonate rocks contain about 60% of the world's oil and gas reserves. For stimulation of wells which penetrate carbonate reservoirs, hydrochloric acid treatments are widely used. The approach is based on the chemical reaction of hydrochloric acid with carbonate minerals. Carbonate reservoirs usually have significant heterogeneity, therefore, when the acid is injected into the formation in the near-wellbore zone of the well, the rock is dissolved non-uniformly. As a result highly conductive filtration channels (wormholes) of complex geometry are formed. The wormholes provide a good hydrodynamic connection between the well and the formation. For a specific rock-acid system, there is an optimal injection rate that allows to get long, low-branched wormholes with a minimum acid injection volume. There are many factors, such as pressure, temperature, acid concentration, injected fluid composition, rock mineral composition, etc. which influence on the optimal injection rate. Laboratory experiments are currently the main method for determining the optimal injection rate. The influence of various factors on the optimal injection rate and the volume of injected acid composition, measured in pore volumes, until the wormhole break through the core sample is studied. The summary of the study is presented. It is shown that factors, which influence on the effectiveness of acid stimulation, have a complex effect and require their simultaneous consideration in laboratory experiments. The results of the analysis were taken into account in planning further laboratory research. As part of the design of acid stimulation for wells of one of the carbonate oil fields in Iraq, the laboratory experiments were conducted to assess the effect of acid concentration and injection rate on the effectiveness of wormholing process under the conditions expected during acid stimulation jobs. The injection parameters have been determined, allowing to obtain the optimal wormholes structure with a minimum acid injection volume. The results of the studies have been successfully used in the design of the acid stimulation jobs for wells in the field.
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Abstract
The problem of involving the enormous resources of highly viscous oil in the more active development is becoming increasingly urgent, which requires the implementation of modern technologies from oil and gas companies. The use of traditional methods of oil production for the extraction of highly viscous oil does not allow reaching the oil recovery coefficient above 15-20%. Thus, the key issue in solving this problem is the selection and implementation of effective technologies for the extraction of such hydrocarbon resources. Currently, there are a number of technologies based on the use of carbon dioxide as an treatment agent, which are successfully used in high-viscosity oil fields around the world. This article is devoted to the review and analysis of the effectiveness of projects for the carbon dioxide injection in high viscosity fields in carbonate reservoirs. Information is provided on the results of the implementation of projects for the injection of carbon dioxide in domestic and foreign fields. To analyze the effectiveness of the projects, indicators such as the ratio of the injected gas volume to the oil recovered volume, the oil recovery coefficient increase and the oil recovery rate per well were selected. The analysis showed that the ratio of the injected carbon dioxide volume to the oil recovered volume could vary greatly depending on the geological and physical characteristics of the deposits. At the same time, during cyclic injection of CO2, a smaller amount was required in comparison with the areal injection. The increase in the oil recovery coefficient can reached 9.14% with an increase in high viscosity oil recovery rate on average up to 3.8 m3/day/well.
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Abstract
The article is devoted to the creation of an effective method and technology of hydro-vortex classification in a fluidized bed of nanoparticles of technogenic mineral formations (TMF) and the development of a mathematical apparatus for calculating its geometric and energy characteristics. Numerous studies show that the efficiency of technogenic mineral formations utilization is limited by high requirements to the fractional composition, median size and dispersion of their particles. The limiting factor in the use of TMF is the insufficient perfection of equipment and technology and their classification. The stringent classification requirements for the variance of the median sizes of TMF necessitate the search for methods and technical means for their implementation, which, under the conditions of the probabilistic distribution of physico-mechanical, geometric, kinematic parameters of microparticles, can effectively implement them. Using the hydrodynamic equations of Boussinesq and the theory of dimensions, a mathematical model of the hydro-vortex classification of micro- and nanoparticles of TMF particles was constructed. The equations of motion of the dispersed system “liquid drop - TMF microparticle” were obtained under conditions of unsteady hydrodynamic inertial supra-Stokes motion during classification as a function of the Euler and Reynolds criteria. The dependence of the diameter of the completely absorbed particles of the components of bulk TMF on the angular velocity of liquid droplets rotation during the hydro-vortex classification was confirmed. It was established that the relaxation time of liquid droplets with integrated micro- and nanoparticles of TMF in the process of hydro-vortex classification depends on their median size. An equation was obtained for calculating the geometric parameters of the Venturi classifier from the required performance and energy characteristics of the hydro-vortex aerator. Certification tests of a pilot industrial model of the Venturi GKV-200 hydro-vortex classifier confirmed the feasibility of separating the TMF microparticles in the range (0.5-5.0) 10-6 with a dispersion of no more than 20%.
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