The Bejil field case study shows the comparison of 3D lithology volumes built by various methods, applied world-wide. A net-reservoir volume is an important and integral part of 3D geological models, which determines the oilnet pay part of the reservoir. The quality of the geological model directly affects the concept of the studied geological environment. Two lithology volume options are considered in detail. The first method, which is more popular in domestic applications, involves building a lithology volume directly based on logging data interpretations. The second method, which is more widespread internationally, involves building a volume of facies environments followed by distributing various lithotypes in a reservoir taking into account the facies structural features. As a result, we made allowance for the tasks and geological features of the field and chose the best modeling method.

The article is devoted to the results of an analysis of geological factors that had a great influence on the filling of Jurassic traps with hydrocarbons. Based on the results of paleotectonic analysis, three key stages of reconstructions of the structural plans of sedimentary cover deposits were identified. Each stage was characterized not only by the appearance of new traps in the interval of Jurassic deposits, but also by the sinking of rocks of Bazhenov formation to a certain depth. It is revealed that in most of the territory of the Uvat district, Bazhenov formation didn't have time to fully realize its hydrocarbon-generating potential. In the Central and Eastern regions it entered the main zone of oil formation only in the Paleogene. Since the development of the relief of modern structural plans of Jurassic deposits in this area occurred in several stages, both the formation of traps and the lateral migration of hydrocarbons also occurred in stages. The first stage of migration occurred at the boundary of the lower and upper Cretaceous, the second stage occurred at the beginning of the Paleogene. As a result, the combined influence of lateral migration of hydrocarbons and the gradual formation of local structures in different areas of the Uvat district led to selective filling of Jurassic hydrocarbon traps.

In order to improve the efficiency of exploration drilling at various greenfield license areas owned by Rosneft Oil Company, Tyumen Petroleum Scientific Center LLC has been actively developing and implementing various innovative technologies in recent years that allow increasing the probability of discovering new hydrocarbon deposits. One of such approaches is the use of different methods based on the principles of fractality of geological objects. The article presents the results of using the fractal analysis method to solve one of the applied problems of oil and gas geology, namely, the correction of the boundaries of facies zones on facies maps, which are the basis for constructing risk maps for the "reservoir". It is shown that the boundaries of the facies zones on facies maps, built mainly on seismic data and a limited amount of materials from exploration drilling, have a large variability. The found statistical relationship between the distribution of the total reservoir thicknesses in different facies zones and the fractal dimension of the traps made it possible to correct facies and risk maps.

As the title implies the article presents the results of many years comprehensive research of the Western Siberian Upper Cretaceous stratigraphy (without Cenomanian). The volume of Upper Cretaceous formation, their biostratigraphic and lithological characteristics are discussed. Based on the analysis of new materials (lithological, biostratigraphic, well geophysics investigation data, magnetostratigraphic, seismostratigraphic), the regional correlation scheme of formations, members and beds has been refined. A new model of correlation schemes, a scheme of facies zoning, and reasonable changes in the nomenclature of the Upper Cretaceous formations are proposed. The Slavgorod and Ipatovo horizons have been replaced by a single Berezovo horizon. Specific properties description of the new suites, established at the first (Okhteurievo, Tagul, Bolshaya Laida, Nizhnaya Agapa), have been done.

Seismic data processing from a floating datum is accompanied by difficulties in estimating effective velocities. These difficulties are associated with the roughness of the datum surface, which, if ignored, leads to artifacts in the estimated effective velocities. The study presents the results of a quantitative analysis of the distortion of effective velocities with model data, as well as the technique to minimize the distorting effect of the elevation on effective velocities. The essence of the method is bringing the sources and receivers within one CDP to a local constant level. This approach has been tested on modeled and real data. It showed a significant reduction in the effect of floating level roughness on kinematic parameters. At the same time, there is no need to modify the processing flow whatsoever.

Currently, most of the fields being put into development are characterized by a complex geological structure, both in terms of section and in terms of plan. The solution of all geological tasks, including such important ones as the preparation of exploration projects, operation and effective development management, is impossible without creating models that reflect the main features of the variability of target parameters. The construction of adequate models of objects with a complex structure requires the involvement of all available information. The accuracy of the geological model is mostly determined by the accuracy of the well correlation. Paleosols are a new marker for the complex-built layers of the VAk-2 and VAk-3(1) of the Tagul field, which contributes to the validity of the correlation of the section of these layers. The reliability of the model was also improved by the use of the results of facies analysis. This analysis showed that the sedimentation of the studied objects includes channel and floodplain facies. Reservoir rock properties of these facies differ significantly. The updated model is characterized by a reduction in the oil-bearing area and the amount of reserves. The implementation of the model will optimize the project fund of wells and reduce the cost of well intervention. Economically, this means reducing capital costs and increasing the profitability of the project.

The microclinoform model of the Neocomian shelf reservoirs is becoming more and more supported by practicing geologists, since it allows to effectively address the problems arising in the development of complex reservoirs. According to modern concepts, the microclinoform structure is due to the intense progradation of delta complexes during periods of forced regression. The article demonstrates the effectiveness of the microclinoform concept in building a geological model of an accumulation in BT₁₀ horizon of Zapadno-Chaselsky field, which is located in the southeastern part of the Russko-Chaselsky large swell in the southeast of the Yamalo-Nenets Autonomous Okrug. The microclinoform structure of the target was mapped based on the data volume of the second derivative of the wave field, which is more sensitive to changes in thicknesses, and porosities of sand reservoirs. As a result of comprehensive studies, correlation profiles and a GDE map of stratigraphic unconformity (top of BT₁₀) were built reflecting the microclinoform structure of the target. The results were used to build a model of a gas reservoir and estimate its reserves. Hydrocarbon discoveries have already been made in the BT group of reservoirs at Zapadno-Chaselsky field and neighboring Yuzhno-Russkoye field that improves the potential of this interval within the southeastern part of the Yamalo-Nenets Autonomous Okrug. This poses the task of its more detailed study based on the microclinoform concept.

The usual method for constructing a digital model of a field is based on hydrodynamic modeling using the basic implementation of a geological model, usually requires additional adjustments to the initial data, and as a result, leads to a wide range of uncertainties in assessing the predicted technological indicators of field development. The PK1 reservoir of a gas condensate field case study discuss-es the method of iterative modeling, which makes it possible to comprehensively approach the assessment of possible uncertainties.

The article highlights the relevance of reliable estimation of the composition and properties of reservoir gas during the development of gas condensate fields and the complexity of the task for reservoirs containing zones of varying condensate content. The authors have developed a methodology that allows monitoring the composition of gas condensate well streams of similar reservoirs. There are successful examples of the approach applied in Achimov gas condensate reservoirs at the Urengoy oil and gas condensate field. The proposed approach is based on the use of the so-called fluid factors, which are calculated on the basis of the known component compositions of various flows of the studied hydrocarbon system. The correlation between certain "fluid factors" and the properties of reservoir gas (usually determined by more labor-consuming methods) allows one to quickly obtain important information necessary to solve various development control tasks.

The article considers the experience of using infill well patten in the territory of Western Siberia. The justification of geological and geotechnical factors affecting the efficiency of infill drilling with the subsequent use of a sector-crushed hydrodynamic model of the field site is given. With the help of the identified criteria, promising areas of infill drilling of wells are mapped, and it is established that increasing the detail of the grid of the hydrodynamic model makes it possible to clarify the localization of remaining oil in place. Based on the obtained results from the hydrodynamic model, variants of adjusted planned well count are compared according to accumulated and annual indicators. Thus, the infill well drilling program is optimized. The implementation of an integrated approach to the selection of sites for compaction drilling and the use of a detailed hydrodynamic model of this site allows to increase the production efficiency of recoverable remaining oil in place, as well as to level the risks of oil production.

The paraffin content in production well streams must be monitored to assess the risks of wax formation during the production, transportation, and treatment of hydrocarbons. This is especially important when operating Achimov reservoirs containing fluids with a high content of heavy paraffin-type hydrocarbons. The standard approach for determining the paraffin content in oil using certified methods involves a long process of sample preparation and separation in selective columns followed by freezing out of paraffin from toluene extract. An urgent task is to find methods for the rapid assessment of paraffin content in condensates. The article considers a method for estimating the mass content of paraffins in condensates based on chromatographic data on the component-fractional and component-group composition of degassed condensate. The authors provide a comparison of the mass fraction of paraffins obtained by the proposed method and measured by the standard certified method.

The authors of the article have summarized the experience of multilateral well application, performed an efficiency analysis of multilateral wells vs horizontal wells in Rosneft Oil Company's fields with various subsurface architecture. The algorithm for multilateral well efficiency estimation, compared to other type of well completions, was developed. This algorithm is based on the selection of areas for well locations with similar reservoir properties, reservoir energy conditions, and reservoir development conditions to evaluate production startup parameters, decline rates, cumulative parameters for the areas of over 6 month production. A matrix of multilateral well applicability in various geological conditions was generated, and recommendations for preferable well design were made. This type of analysis was conducted for the first time due to collection of sufficient statistical data, because of a multiple increase in the amount of drilling complex wells in the recent years. The obtained results provide an opportunity to design an efficient field development system for new assets, perform an adjustment of brownfields development systems, select multilateral well design for certain geological conditions based on lessons learned.

The article presents the author's formulas for calculating the residual oil saturation and the end points of relative phase permeabilities that dynamically depend on the filtration rate of reservoir fluids and capillary numbers. The dependences of the residual oil saturation and the end points of the phase permeabilities on the capillary number are investigated and described. An element of a five-point system for the development of an oil deposit case study shows the possibility of calculating oil targets using dynamic phase permeabilities. The difference between the model with static relative phase permeabilities and the model with dynamic phase permeabilities should be stressed. The text gives valuable information on the dependence of the simulation results on the parameters of the nonlinearity of the filtration processes with the traditional filtration-capacitance properties of the oil deposit model unchanged.

The article is dedicated to the problem of adapting the hydrodynamic model of a gas-condensate reservoir with a low volume and low reliability of the field and laboratory data. The purpose of the work is a qualitative reservoir development forecast. All available formation fluid downhole samples were studied. The authors analyzed water samples taken during the reservoir development process. The monthly production reports data and the gas-condensate well testing installation measurements were used in the article. The authors carried out the hydrodynamic model multivariate calculations in order to mathematically repeat historical waterflooding. An approach to the retrospective analysis of the production and laboratory data is shown in order to remove uncertainties in the reservoir and production engineering. The work performed made it possible to determine the most probable content of C₅₊ components in the reservoir gas, as well as to assess the risk of the future formation water invasion into the reservoir. As a result of this work, it was recommended to exclude two edge wells in order to reduce the gas well waterflooding. In addition, the authors calculated an improved reservoir development variant. They proposed to transfer a part of gas wells to water wells at the stage of declining production. This operation will reduce the reservoir water-flooding rate.

One of the key strategic directions of the long-term program for the development of the oil and gas industry is the development of the resource base, including through the acquisition of new licenses at auctions and tenders held by Russian government agencies. To make a prompt decision to purchase a license area, it is necessary to carry out an objective technical and economic assessment. Official resources contain a minimum of initial data for making a decision, which led to the need to create a unified information system for assessing subsoil plots, accumulating information on new unallocated plots. The article gives valuable information about the main capabilities of the unique information resource, which was developed by specialists of Tyumen Petroleum Scientific Center LLC. This information resource is intended to provide the Company's specialists with a tool for rapid assessment of subsurface areas based on complex parameters of geology, development, infrastructure and economics in order to make a decision on the feasibility of acquiring an asset.