Search

The issues of improving the efficiency of processing the results of studies of the filtration properties of reservoirs within the oil and gas producing areas of the central part of the West Siberian oil and gas province are considered. The high degree of development of the hydrocarbon resources of the studied territory is characterized by the presence of long-term developed deposits, which determines the solution of tasks aimed at increasing the success of the search for complex deep-lying reservoirs, the efficiency of their exploration and additional exploration, since the overlying productive horizons are practically developed. This task is one of the most important at the current stage of field development in this region, in the context of falling oil production at the main large fields, and has no unambiguous solution.This article covers the issues of reservoir modeling using new scientific and methodological approaches to the processing of geophysical data and the possibility of using modern software products when grouping development objects according to criteria corresponding to a reservoir of a certain lithotype. This approach allowed us to build high-quality geological models and justify the use of the most effective complex of geophysical studies for modeling low-amplitude (no more than 15 m) and small-sized (less than 20 km2) oil deposits. In the course of research: The results of the reservoir filtration properties were processed; low-amplitude and small-size sediments of channel sediments (river valleys) were established; the industrial oil and gas content of complex sediments characterized by low-amplitude and small-size sediments (Tyumen formation, object Ю2) was proved; The interpretation of geophysical studies of wells was carried out, the results were compared with the energy characteristics of the reflected waves (seismic studies), zones saturated with water-oil-gas fluid were established (3D models were built), and the possibility of using this technique for identifying and mapping complex deep oil deposits was shown.

There were examined the issues of studying the features of the lithological and petrographic composition and the formation of oil deposits within the fields of the Surgut dome fold and the Frolov megadepression. It was noted that the formation of deposits of the sedimentary cover is associated with the peculiarities of the geological structure and the oil-bearing capacity of the basement rocks. In the considered territory, a high level of oil-bearing sedimentary cover is observed within the central part of the Surgut dome fold, and the deposits of the Pre-Jurassic part of the section can be additional sources of intensification of hydrocarbons in the Lower-Middle Jurassic deposits. The presence of zones of deep snaps is a search criterion for the detection of secondary reservoirs in them both — in destruction zones, basement, and in the Lower-Middle Jurassic deposits, therefore, deposits can be formed due to the vertically ascending migration of deep fluids through faults that cross the basement and horizons of the sedimentary cover.There were examined the issues of the prospects for the oil and gas content of the Lower-Middle Jurassic deposits, which must be associated with both granitoid massifs and the details of identifying the conditions of sedimentation and the establishment of contact zones of the sedimentary cover with the underlying formations.

The use of geophysical well logging for interpreting structurally complex oil-saturated intervals of the Lower and Middle Jurassic horizons that are characterized by a high average number of permeable intervals and by the presence of semiconductor minerals (pyrite, siderite, glauconite, and others) is considered. The complex of geological and geophysical information that has been aggregated and research methodology that has been developed for areas with hard-to-recover reserves is developed based on the example of deposits that have been in operation for many years.

This paper discusses the use of geophysical well logging for the interpretation of complex structure oil-saturated intervals of the Lower and Middle Jurassic horizons with high average number of permeable intervals, the content of minerals — semiconductors (pyrite, siderite, glauconite, et al.) for structuring a complex of geological and geophysical information and developing a researching methodology of areas with hard to recover reserves on example of deposits which was in operation for an extended period of time.

A series of core experiments has made it possible to establish that for fractured samples, reservoir properties decrease sharply as their stress state (effective pressure) increases. With a further decrease (or complete removal) of the stress state, reservoir properties are not recovered in fractured reservoirs. These experiments have scientific and practical importance for the optimization of practices of production-well operation in the Tournesian–Famennian fractured reservoirs.

Coalbed methane (CBM) is a new environmentally friendly unconventional energy source of great promise for exploitation. The CBM resources in the Qinshui Basin are as great as 3.97 × 1012 m3, i.e., 10.8% of the total coal gas resources of China. Compared to the main coal basins of the United States, Australia, Canada, and Russia, the Qinshui Basin is characterized by high metamorphism, high gas content, and low values of porosity and permeability, as well as by low formation pressure. The commercial exploitation of productive beds at the Qinshui Basin requires the use of efficient technologies of stimulation. Vertical wells with hydraulic fracturing (HF) predominate at the Qinshui Basin. The CO2 injection, electric pulse, multistage HF, etc. technologies are used as well.

The specific aspects of the evaluation of the efficiency of flow diverting polymer flooding (FDPF) for enhanced oil recovery are discussed. It is demonstrated that the zeroing of the FDPF effect on enhanced formation fluid withdrawal leads to the overestimation of the total FDPF effect. The FDPF effect evaluation procedure based on the evaluation of the effect on each responsive production well and the subsequent summation of all effects, as currently used by oil companies, leads to the selective evaluation of only positive constituents of the FDPF effect. The neglect of the negative constituents leads to overestimation of the summary effect of FDPF. Examples of unjustified overestimation and underestimation of FDPF efficiency based on the evaluation procedures used by oil companies are discussed.

Coalbed methane (CBM) is a new clean and unconventional energy that has broad space for development. In Qinshui basin, CBM reserves reach 3,97·1012m3, which is 10,8% of the total resource in China. Compared to the main coal basins of USA, Australia, Canada and Russia, coal seams in Qinshui basin have the characteristics of high metamorphism, high gas content, low porosity, low permeability and low reservoir pressure. Therefore, effective stimulation treatments must be used in Qinshui basin to realize industrial exploitation of CBM. At present, vertical wells with hydraulic fracturing are dominated in Qinshui basin. In addition, injection CO2, electric pulse, multi-stage fracturing and other technologies are also applied to the CBM exploitation.

Based on the stress distribution model of a horizontal well, the calculation model on the fracture pressure of the coalbed methane (CBM) horizontal well is developed. This model deals not only with initiation of the matrix fracture, but also of shear and open fractures. The effects of the cleat parameters and spatial orientation of the well on the fracture character are considered.

The article is devoted to the history of development and the formation of selection, which historians and specialists of this field began to pay attention to in the last two centuries: L. Sempolovsky (1897), D. Rudzinsky (1904), M. Goncharov (2005) and many others. This was due to the fact that varieties more often become a means of production, greatly increase the productivity of agriculture. The term "selection", its origin has not been studied, which leads to its various interpretations: sorting and even seed production. However, K. Timiryazev (1938) gave a more faithful notion of the term "selection" K. Timiryazev (1938), the selection (from the Latin word selection), means the choice by the practical way of improved, the emergence of new forms of cultivated plants, or domestication animals for a certain area. All indigenous wheat varieties are the result of breeding. However, as a new species and varietal diversity were created, the data were not preserved, and the results of selection researchers make conclusions on the number and quality of the varieties found of species. In 1931, 10 large agricultural centers were organized, which included 165 selection stations, and the construction of phytotrons, greenhouses and other selection structures began, which greatly increased the efficiency of the selection process. In the 90s of the last century, 51 scientific institutions were engaged in the selection of wheat in Ukraine, where 282 varieties of winter wheat with a yield of 5-7t/ha were created and transmitted to the State Variety Testing. Today, in Ukraine, winter wheat selection is conducted by 101 scientific institutions. However, the greatest achievements in the development of winter wheat varieties have been achieved: the Selection and Genetics Institute – the National Center for Seed Research and Graduate Studies – 59 (17.8%) varieties, the Institute of Plant Physiology and Genetics of the National Academy of Sciences – 65 (19,1 %) and Mironovsky Wheat Institute after V.M. Remesla – 23 (6,7 %). The varieties of these institutions are capable of yielding 10,9–14,0 t/ha.

Coalbed methane (CBM) is clean unconventional energy that can be exploited with stimulation treatment to realize commercial value, and hydraulic fracturing is the key technology for increasing CBM production. The simulation of hydraulic fractures is an important research content that can guide the engineering practice to achieve the purpose of increasing production. Based on the distribution characteristic of cleats in coal, the research on the propagation of hydraulic fractures is carried out via Discrete element method (DEM). The simulated results show that: hydraulic fractures mainly propagate along the cleats towards the maximum principal stress. The fracture network can be formed due to the intersection of face cleats and butt cleats that can propagate at certain pressure. During the injection process of fracturing fluid, the pressure at injection point decreases with the fracture propagation until the pressure tends to be stable. With the increase of injection rate and fracturing fluid viscosity at the same condition, the maximum aperture of hydraulic fracture increases, while the length of principal hydraulic fracture shortens. Therefore, to achieve the purpose of forming hydraulic fracture network in coal seams with cleats, low viscosity fracturing fluid and low injection rate need be applied to the fracturing technology. As the cleat density increases, the number of branch fractures increases, but the length of principal hydraulic fracture becomes short. Long and narrow hydraulic fractures are easily formed in coal seams with lower cleat density.

Enhanced oil recovery (EOR) process selection is an important part of field development strategy. One of the most important categories of EOR methods utilize certain chemical components that enhance the fluid properties. Polymer-enhanced waterfloods are one of the examples. During conventional waterfloods, the flow characteristics and displacement efficiency usually depends on a certain rock type in study. In a chemical EOR flood, there are a large number of parameters needed to be defined and optimized that impact process efficiency. The attempt to execute corefloods for various combinations of these parameters for each rock type would lead to a large number of tests not executable in a time frame compatible with timely decision making. And the destructive nature of the experimental chemical EOR floods prohibits repeated testing on the same core sample. The natural difference between the samples selected for the study can prevail over the process efficiency difference related to the certain design parameter in the study. Digital core analysis can help to optimize design of EOR floods and reduce the associated uncertainty. In this work we apply digital core analysis to investigate the dynamics of oil displacement, using water and water-based polymer solutions in porous media. The described technology application includes scanning of core samples using X-ray microtomography, creating digital models for the samples in study, and running pore-scale hydrodynamic modeling using the density functional hydrodynamics (DFH) method, which combines density functional theory with compositional multiphase hydrodynamics. The results include visual snapshots of phase distributions at pore scale for various times during the waterflooding and polymer solution flooding at various concentrations. Polymer-enhanced waterflooding increased the displacement coefficient by almost 2% and 20% for low- and high-concentrated polymer solutions, respectively. This effect was further explained by analyzing the dynamics of oil displacement on a pore scale. The results show an exemplary sensitivity study that investigates the dependency of the displacement coefficient on the polymer solution type and concentration. Additional sensitity studies with varying design parameters (slug size, injection sequence, polymer type, etc.) can be also performed.

The 2014 Australian presidency took place against the backdrop of multiple challenges in both global economy and international politics, with Ukrainian crisis, Syrian conflict, Islamic State, and Ebola. Thus, despite being an economic forum, the G20 could not avoid addressing these issues, with discussions taking place during the bilateral meetings and on the sidelines of the forum. The article attempts to analyze the Australian G20 Presidency within a functional paradigm, assessing G20 performance on the three main objectives of plurilateral summitry institutions: strengthening capacity for political leadership to launch new ideas and overcome deadlocks; reconciling domestic and international pressures; and consolidating collective management. The analysis revealed that, despite a number of setbacks, the 2014 Australian presidency managed to steer the G20 members’ cooperation on the four major pillars of the institution’s agenda, reflecting a consistently high level of the G20 commitment to fulfill ing its key mission of ensuring strong, sustainable, balanced and inclusive growth. The research was carried out with financial support of Russian Humanities Research Foundation within the framework of a research project “Elaborating a Supply – Demand Model to Balance External Demand and National Priorities in the Presidency Proposals for Agenda in G20, G8 and BRICS”, project ¹12-03-00563.

The western Siberian basin contains some of the largest oil fields in Russia and the former Soviet Union. In early 2000, LUKOil, in cooperation with PetroAlliance, completed the largest integrated reservoir study ever undertaken in the region. The project spanning nearly four years culminated in an enhanced 3D geological and reservoir models of the giant Vatyogan oil field, which holds over 1 billion tons of calculated oil reserves. The major technical objective was to utilize state-of-the-art technology to create a new 3D geological model of Vatyogan’s six major producing zones, which range in age from Upper Jurassic to Upper Cretaceous and cover a wide range of depositional environments. The new geologic model would form the basis for reservoir simulation models which would guide further operational and development activities in the field. Specific tasks to be accomplished with the new model include: In undeveloped areas: Estimate reserves and prepare a drilling programIn developed areas: Identify areas of by-passed oil and develop an optimum infill drilling and enhanced recovery program to improve production. A multi-disciplinary team of 25 specialists was involved in various stages of the project. The study began with the creation of a digital database of 3,800 wells from paper records. Newly acquired data such as: 2D and 3D seismic, log data, and high precision gyroscopic surveys were incorporated into the revised models. This paper describes the processes employed in the project and highlights some of the stumbling blocks. Details are provided describing data management, geological modeling, upscaling and history matching of thousand of wells. Conclusions illustrate how data from the specialized logs and high precision gyroscopic surveys resolved numerous questions and contradictions in the existing data, providing improved reservoir structure analysis and more accurate fluid-contact depths--data which significantly impacted both the models and the simulation forecasts.

Meromorphic solutions of algebraic differential equations by A. E. Eremenko Some questions in spectral theory for the operator Sturm-Liouville equation on the half-line by M. L. Gorbachuk and V. A. Kutovoi On the connection between spectral and oscillatory properties of the matrix Jacobi problem by V. S. Bondarchuk On the numerical solution of the Cauchy problem for ordinary linear homogeneous differential equations on large intervals of integration by S. F. Zaletkin On the solutions of a uniformly elliptic complex equation of first order connected with the convergence of analytic functions by S. A. Akhmedov On the behavior of solutions of the equations of plane elasticity theory in the neighborhood of irregular boundary points and at infinity by O. A. Oleinik, G. A. Iosifyan, and I. N. Tavkhelidze The Dirichlet problem for the Laplace operator in the exterior of a thin body of revolution by M. V. Fedoryuk Variational methods in a mixed problem of thermal equilibrium with a free boundary by B. V. Bazalii and V. Yu. Shelepov On an estimate of $N^\ast(\lambda)$ for the series of quasimodes of the Laplace operator by V. F. Lazutkin On the selfadjointness and maximal dissipativity of differential operators for functions of an infinite-dimensional argument by Yu. L. Daletskii Selfadjoint differential operators acting in spaces of functions of infinitely many variables by Yu. M. Berezanskii.

The dynamics of oil displacement using water and gas mixtures in porous media is studied using digital rock analysis. The technology includes scanning of core samples using X-Ray micro tomography, creating of digital models for the samples, and running hydrodynamic modeling on pore scale using the density functional approach. The results include visual snapshots of phase distributions on pore scale for various time instants of oil displacement by water and water-gas mixtures. Due to WAG the displacement coefficient was increased by 5% to 10.5% for water-wet samples and by 20-21% for oil-wet samples. This effect was explained by analyzing the dynamics of oil displacement on a pore scale. The simulations also allow studying the dependency of the displacement coefficient on WAG regimes for water-wet and oil-wet media.