The development of Western Siberia is one of the most large-scale scientific, industrial and socio-economic projects of the country in the 20th century. The state approach, scientific substantiation, production of the necessary equipment, organization of transport and exploration work were linked into a single integrated state project. As part of the USSR Ministry of Geology, the Main Directorate for Oil and Gas Exploration was created, and on January 15, 1948, an order was signed to organize the first oil exploration expedition in Tyumen. In January 1950, the Scientific and Technical Council of the USSR Ministry of Geology adopted a master plan for the study and development of the West Siberian Plate, including the placement of 26 reference wells, regional seismic profiles and prospecting in the area of reference wells on its territory. As a result, the gas fields of the Berezovskiy region and the Shaimskoe, Megionskoe and Ust’-Balykskoe oil fields were discovered. Efficient organization of work and the state approach made it possible to discover large oil reserves in the Shirotny Ob region and unique natural gas reserves in the north of Western Siberia in a short time. In December 1963, a special resolution of the Council of Ministers of the USSR on preparation for the trial operation of deposits, on the creation of infrastructure for the development of geology and oil production, research and industrial institutes was adopted. Achievements of geologists have provided the necessary basis for the creation of the largest fuel and energy complex. It was associated with the social and economic development of the region and the country.

An analysis of the state and changes in the resource base of the Yamalo-Nenets Autonomous Okrug and the Kara Sea shelf has been carried out. Data on production, reserves and resources of gas, oil and condensate are given. The distribution of hydrocarbon reserves by the field size, by licensed and unlicensed fund and oil and gas complexes are shown. The ratio production and reserves growth over a 20-year period is shown. The reserves of the region’s industrial categories make it possible to increase the annual gas production to 650–750 billion m³ , oil – up to 80 million tons. It is necessary to carry out a differentiated assessment of the initial total resources of hydrocarbons for the complex of geological and field parameters.

The history of creation is given, the complex of studies carried out by the Tyumen branch of Siberian Research Institute of Geology, Geophysics and Mineral Resources (SNIIGGiMS) in 1960–1964 and by West Siberian Research and Geological Prospecting Oil Institute (ZapSibNIGNI) in 1964–1996 is analyzed. The role of the Institute in the substantiation of oil and gas potential and developing the resource base of the West Siberian oil and gas province is shown. The scientific forecasts and developments of the Institute’s employees, which influenced the increase in the efficiency of geological exploration are presented. In preparing the article, previously unpublished documents from the archive of the Directorate of ZapSibNIGNI were used.

An analysis of historical statistical data on the hydrocarbons growth and drilling during prospecting and exploration of oil and gas fields in the Shirotny Ob region made it possible to identify important patterns in the dynamics of work efficiency criteria. The obtained calculations of the specific annual and average longterm efficiency of prospecting and exploration works can be used to plan drilling meterage, estimate the time of drilling operations and calculate their cost. The feasibility of carrying out prospecting and exploration drilling to convert regional resource expectations into proven reserves of commercial categories is assessed.

The distribution of cumulative production and current oil reserves of all categories, differentiated by administrative subjects located within the West Siberian oil and gas province, shows significant heterogeneity in the distribution of these indicators across stratigraphic horizons. For each horizon, an integration of the reserves-to-production ratio criterion (A category) and water cut is carried out. It is shown that the main share of both cumulative production and current recoverable reserves that ensure this production falls on the Neocomian complex, which has critically high water cut and low flow rates.

This research aims to analyze problems related to resources, reserves and development of Bazhenov-Abalak oil and gas play and to find geological and technological solutions for bringing reserves into development commercially. This should stabilize oil production in Okrug on the level 210–215 million of tons. Geological, field and statistical data from V.I. Shpilman Research and Analytical Centre for the Rational Use of the Subsoil and Department of Subsurface Management & Natural Resources of Khanty-Mansi Autonomous Okrug – Yugra were retrospectively analyzed during this research.
Oil production from Bazhenov-Abalak play using conventional technologies is still sub economic. Running experimental areas and test ranges for industrial approval of development efficiency enhancement technologies for Bazhenov-Abalak play are created on producing fields. Unfortunately, accumulated experience ends up inside oil companies. Undoubtedly, single initiatives of oilmen will not solve a problem of development of huge resources in Bazhenov formation.

The goal of the article was to analyze the mineral resource base of hydrocarbons of zones promising for the discovery of hydrocarbon deposits, located mainly on the periphery of the territory of the Khanty-Mansy Autonomous Okrug – Ugra. The second, no less important goal was to analyze the efficiency of exploration work in Ugra. Sites of subsurface resources were identified, for which an assessment of the resource base of pre-Jurassic formations and sedimentary cover was given. The most promising prospecting zones in terms of the state of reserves and resources are proposed for their inclusion in the licensing programs of the subsoil fund at the expense of all sources of funding. Information about the prospects for the preparation of «new» oil reserves through exploration drilling is given.
This work is the result of the authors’ own research, including a retrospective analysis of unpublished material and available material of the V.I. Shpilman Research and Analytical Centre for the Rational Use of the Subsoil and the Department of Subsurface Management & Natural Resources of Khanty-Mansi Autonomous Okrug – Yugra geological and on this topic for the history of discovery and development of subsoil West Siberian oil and gas province.

In order to replenish oil and gas reserves in the medium term and until the end of the century, it will be necessary to study new sediment complexes in promising regions of the country. One of these areas is the Kara Sea shelf, where large and giant gas condensate fields have already been discovered in the Cretaceous deposits, and the Pobeda field has been discovered on the eastern Prinovozemelsky shelf, with an oil deposit in the Lower-Middle Jurassic deposits and gas deposits in the Cretaceous.
The article substantiates the prospects for the oil and gas potential of the Jurassic complex in the central part of the South Kara oil and gas region and the strategic need for geological exploration in the Jurassic and pre-Jurassic deposits of the region.

The paper is aimed at the prediction of oil and gas occurrence of the Upper Permian, Lower Triassic and Lower Jurassic deposits in the Vilyui hemisineclise. The basin modeling research implies the Upper Paleozoic and Mesozoic petroleum system model of the Vilyui hemisineclise. The initial generation time at the bottom of the Permian source rock is 270 Ma. The most intense generation of hydrocarbons is found to be in the late Permian and early Triassic. The generation power of the Permian source rock is 800 trillion m3 . The hydrocarbon losses is up to 90% in consequence of unfavorable seal properties of the Lower Triassic and Lower Jurassic clay formations. All the potential hydrocarbon traps of the Vilyui hemisyneclise are considered to be formed during the Cretaceous stage of development. There is therefore an appropriate environment for the hydrocarbon accumulation to be in progress. The interpretation of geological and geophysical data identifies the areal extent prediction of sand reservoirs and overlying clay interlayers of high quality in the Upper Permian and Lower Triassic seals. The goal of a comprehensive approach to the sedimentary basin research is to divide the territory into oil and gas zones of various prospects in relation to the factors controlling hydrocarbon deposits.

The article presents the first data on rare earth mineralization in differentiated intrusions on the western slope of the Southern Urals. When studying the mineralogy of the rocks of the Shuida, Misaelga, Ishliy and Lysogorsk complexes, minerals of rare earth elements (monazite-(Ce) and allanite-(Ce), thorite (auerlite, cheralite)) and REEbearing minerals (zirconolite-(Y) and epidote). A detailed analysis showed that igneous monazite-(Ce) and allanite- (Ce) are significantly different from the metamorphogenic analogues previously described in various structural-material complexes of the region. It is concluded that rare-earth mineral formation in rocks of basic/ultrabasic composition is due to differentiation of the melt in the magma chamber. Close temperatures of formation of minerals from different complexes (Ishliy complex – 958°C, Shuida complex – 950–954°C, Misaelga complex – 947–952°C) testify to the identity of the processes of formation of monazite-(Ce) and allanite-(Ce). opinion, the chemistry of the environment of mineral formation.

An original model of microstructural transformations during clay swelling is considered, a thermodynamic and physical-mechanical description of the properties of clays during the process of swelling in vapors and aqueous solutions is given. The model proposed to explain these properties is based on the concept of mutual displacement of clay particles in clay rock aggregates during swelling with the formation of new pores between clay particles forming crystallites and aggregates. The model is based on the mechanism of utilization of the excess surface energy of clay particles during hydration, taking into account the influence of certain environmental parameters, for example, the concentration of the solution, through a change in the mutual orientation of clay particles, mainly due to rotations or shifts relative to each other, with the formation of an area available for further wetting free surface. In the thermodynamic description, such a process will manifest itself in a change in the surface interaction energy on the wetted areas of the particles when moving during mutual shifts and rotations. At the same time, one of the most important parameters of clay rock, microporosity, also changes. In this work, this phenomenon was experimentally studied using the methods of static moisture capacity and Mössbauer (NGR) spectroscopy. The proposed model makes it possible to explain the features of the clay hydration process and to compare the observed experimental data with the theoretical description of the clay swelling process.

To date, significant foreign and domestic experience has been accumulated in the construction and operation of horizontal, multilateral and multilateral wells, as well as the restoration of an idle well stock by drilling sidetracks and sidetracks into various productive formations: low-permeability and highly dissected, with low values of effective oil-saturated thicknesses, degraded hydrodynamic connection with the contour area, etc. In this regard, it becomes extremely important to make a decision on choosing the optimal well profile in specific geological and physical conditions. The relevance of the work is also confirmed by the fact that at some development sites there is a decrease in the oil production rate of horizontal wells to the level of directional wells in the initial period of operation. Based on a significant difference in the reservoir properties of oil fields in the Perm Territory, all the analyzed objects operated by horizontal wells are combined into several groups: “northern” (N) and two “southern” (S₁ and S₂ ). The main parameter in the selection of groups was the coefficient of mobility of oil. The well-by-well technical and economic assessment performed in the article, based on the actual values of production over a long period, made it possible to identify the optimal well profile depending on the geological and physical characteristics of the reservoir. Combining the main geological characteristics that affect the technological parameters of well operation, with an economic assessment, the dependences of the net present value on the formation hydraulic conductivity were built. Dependences built for the first time make it possible to reasonably select the well profile in specific geological and physical conditions. Also in the work for a variety of geological and physical conditions, the value of the minimum profitable oil production for various well profiles is determined. Thus, the basis has been created, which is necessary for determining the profile of wells when planning production drilling.

The objective is the junction zone of the multilateral fishbone wellbores planned at the Yamalo-Nenets Autonomous District oilfield. Reservoir rock stability around the junction area is estimated with the help of the full coupled 3D poroelastic modeling. In order to determine the optimal fishbone location, the different cases with the various sidetrack inclination, parent well orientation along the maximal and minimal horizontal stresses with the condition of sidetracking in the rock with standard and reduced strength were simulated. The permissible depression and repression values were estimated for each fishbone configuration. For the cases with unstable junction the safe pressure drop and overbalance for drilling regime were determined. It was shown that in the case when mudcake is formed on the wellbores wall the pressure drop can be essentially decreased with fishbone stability retention.

The boundary value problem of transient pressure field development around a horizontal well in a laterally infinite, inhomogeneous, anisotropic reservoir is formulated under assumption of slow spatial variation of the matrix permeability along the well axis. The well is represented as a linear fluid source/sink. The pressure distribution is expressed in the integral form on the basis of the instant point source perturbation function found explicitly. The inverse problem for fluid in/outflow density rates simulation is reduced to solution of the integral equation at a given pressure inside the well. A computational procedure is developed and implemented to predict the in/outflow rates along the well and estimate the impact of the permeability variations on the well performance. Series of calculations for constant, linear, and variable permeability cases are analyzed and compared. The difference of the obtained solution from the so-called “locallyconstant” permeability approximation is demonstrated, accuracy and applicability of the latter approach are discussed.