pre-Jurassic Deposits Research Articles

Pre-Jurassic weathering crust of the Kalinovoe hydrocarbon deposit, Tomsk region: composition and structure characteristics

Abstract. The study of pre-Jurassic deposits in the southwestern part of Western Siberia is highly relevant due to their potential of increasing hydrocarbon resources. These deposits are considered prospective targets for the discovery of hydrocarbon accumulations. Weathering crusts developed on the upper part of the Paleozoic rocks in the Tomsk region exhibit a complex composition and structure, reflecting the interplay of various factors, including primary sedimentary processes and later alteration processes, including fracture-controlled fluid flow and metasomatism. Aim. To establish the characteristics of the mineralogical composition and structure of the Paleozoic weathering crust formations developed at the Kalinovoe oil-gas-condensate field. Methods. Optical microscopy, X-ray diffraction, scanning electron microscopy. Results and conclusions. The composition and structure of the deposits at the boundary zone between the Paleozoic and Mesozoic successions have been studied in detail in the section of one of the wells at the Kalinovoe oil-gas-condensate field. The factual material is represented by core and thin sections of weathering crust deposits. The primary rock-forming minerals are silica minerals (quartz, chalcedony and opal) and clay minerals, with a lesser amount of carbonate minerals (siderite). Different lithological units were identified based on the content of minerals and bioclast (radiolarians and sponge spicules), indicating their formation under marine conditions. The protoliths of the altered rocks were carbonate-siliceous rocks, argillaceous limestones, and radiolarian cherts, which as a result of multiple stages of hydrothermal alteration and metasomatic processes were transformed into argillaceous-silicified rocks. In these rocks, with intense post-alteration overprinting, good reservoir quality porosity can develop. This porosity includes biogenic voids, microcavities, micropores, and open fractures.

Stratigraphic, lithological and petrographic characteristics and oil and gas potential of the pre-Jurassic deposits of the Barsakelmessky trough and adjacent territories

The article discusses the lithological and petrographic properties of pre-Jurassic sedimentary rocks under the influence of the Barsakelmes pipe and the drilling of wells in the adjacent territories. The results of substantiating their age are also presented. In the section of pre-Jurassic deposits, 8 lithostratigraphic complexes have been identified.

Oil sources of the Krasnoleninskoe field

There is no consensus on the role of different source rocks (SRs) in the formation of the Krasnoleninskoe field. The main Upper Jurassic-Early Cretaceous SR of Western Siberia is represented on the Krasnoleninsky arch by the Tutleim formation (fm) (J3tt–K1v). It is overlain by argillaceous rocks of the Frolov fm (K1v–K1a), underlain by the Abalak (J2cl–J3km), Tyumen (J2a-b), Sherkalin (J1) formations and folded pre-Jurassic basement. All these formations potentially contain SR layers. The purpose of the article is to determine the sources of oil in the Krasnoleninskoe field by comparing oils with SRs and to determine of the history of oil composition formation. Based on a review of known geochemical parameters and the results of statistical analysis new molecular parameters for determining the type of organic matter (OM) and its maturity are proposed. A secondary processes of the oils of the Vikulov fm of the Kamennaya crest has been established, which is associated with the migration of hydrocarbons from the Vikulov fm to the overlying deposits. It is shown that the oils of the Vikulov fm of Kamennaya crest were formed from the SR, which was at the MC2 substage during the generation of hydrocarbons, and the oils of the Jurassic and pre-Jurassic deposits were formed on the end of MC2-beginning of MC3 substages. It was determined that the oils of Kamennaya crest have aquatic initial OM, aquatic OM was found in the Tutleim and Tyumen SRs. According to the criteria of OM type and its maturity, the source of Kamennaya crest oils cannot be determined; therefore, genetic features of the difference between the aquatic OM of the Tyumen and Tutleim formations were found. These features made it possible to estimate the source of oils for different parts of the Krasnoleninskoe field: for Kamennaya crest the Tutleim fm, for the Talinskaya area the Tyumen fm, for the Em-Egovskaya area, the Tyumen and Tutleim formations. Estimation of the contribution of the Sherkalin and Abalak SRs to the formation of hydrocarbon accumulations is beyond the scope of current work.

Substantiation of the prospects to discover large oil and gas accumulations in the Jurassic and pre-Jurassian deposits on the Kara Sea shelf

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.

Prospects of the oil and gas potential of the pre-Jurassic deposits of Southern Mangistau, the direction of further prospecting and exploration, and some issues of the methodology of their implementation

In this paper, the authors present the features of the geological structure of the pre-Jurassic rock deposits of the Mangyshlak oil and gas complex. A brief analysis of the identified objects is given, prospects are determined, and proposals are given for the further direction of setting up prospecting and exploration work for oil and gas.

Main types of reservoirs of pre-jurassic deposits in the Ustyurt region

This article compiles and presents the tangible records encompassing drilling operations, testing procedures, and geophysical loggings conducted in the Ustyurt oil and gas region of Uzbekistan. These consolidated materials provide a comprehensive overview of the exploration efforts undertaken in this region. The dataset includes information on core samples extracted from drilling, their subsequent analysis, and the outcomes of tests conducted on intervals within the Pre-Jurassic deposits. Through a meticulous examination of core samples, drilled wells, and geophysical loggings, the study delves into the reservoir properties of rock formations in this geological region. The research identifies distinct groups of rocks within the Pre-Jurassic complex, categorized by their porosity characteristics. This categorization serves as a foundational step in understanding the geological composition and potential reservoir properties of these formations. An important outcome of this analysis is the identification of five distinct types of reservoirs based on the structure of the pore space within the pre-Jurassic sediments. This categorization holds immense potential for future predictions and assessments concerning these sedimentary deposits. By amalgamating core data, geophysical readings, and testing outcomes, the research contributes to a holistic understanding of the geological attributes and reservoir potential of the Ustyurt oil and gas region. This foundational information sets the stage for informed decision-making in exploration, production, and resource management activities within this significant geological area.

Prospects for the exploration and development of large oil and gas deposits in megareservoirs in of the West Siberian oil and gas province

Prospects of exploration and additional growth of gas and oil reserves in Cretaceous, Jurassic and Pre-Jurassic deposits in the northern part of the West Siberian oil and gas province, including the Arctic shelf of the Kara Sea, are considered. The economic feasibility of carrying out prospecting and exploration and development of oil and gas resources in Arctic conditions at large deposits associated with megareservoirs is substantiated. The conditions for the formation of large and giant hydrocarbon accumulations are considered. The issues related to their confinement to various types of traps and rocks of different lithological composition are discussed. The measures to achieve profitability and efficiency of exploration for oil and gas in difficult natural and climatic conditions of the Arctic are underpinned.

Crustal waveguides of sedimentary deposits and conditions for their operation

The relevance of the article is determined by the need to develop the theory of crustal waveguides as a new look at the processes of formation of various hydrocarbon deposits. The purpose – identification of new structures – crustal waveguides – active fluid-saturated zones, within which certain types of traps for hydrocarbons can be formed. Research methods. The article analyzes literature sources that consider the phenomenon of oil formation as a result of the evolution of fluid-saturated zones of crustal waveguides and data from X-ray diffraction and electron microscopic analyzes of layered silicates. Results. The conditions for the operation of crustal waveguides are considered from the standpoint of the presence of free matter, methods of its delivery and energy sources, and features of the formation of their structure. The data of studies of the mineral composition of the rocks of the North-Tazovskaya depression of Western Siberia and the features of their hydrothermal-metasomatic alterations are presented. Minerals and their parageneses have been established, indicating the presence of hydrothermal processes accompanying crustal waveguides. The article argues that the processes of alteration of host rocks in various zones of crustal waveguides lead to the formation of special hydrocarbon traps of an unconventional type, established for deep Jurassic and pre-Jurassic deposits in the north of Western Siberia. The theory of crustal waveguides makes it possible to find the relationship between the formation of oil and gas fields and the geoenergetic aspects of the problem of the removal of intraterrestrial heat in various forms, the main of which is hydrothermal activity. The conclusions summarize the main provisions of the theory of crustal waveguides of sedimentary deposits, the conditions for their operation. The necessary conditions are: the presence of free matter in deep zones, energy sources of self-oscillations of the sedimentary strata and deep faults containing them as a result of unloading the stress field of a special kind, taking into account the depths of their formation. Conclusions are also drawn about the mineral composition of hydrothermal solutions associated with crustal waveguides, which affect host rocks and lead to the formation of a new type of metasomatic traps for hydrocarbons.

Oil and gas bearing complexes of the pre jurassic deposits of Southern Mangistau and their characteristics

The article is devoted to the features of the geological structure on the example of the analysis of the pre-Jurassic complex of the South Mangistau with recommendations for determining the further direction of prospecting and exploration.

Identification of the features of the organic matter of oils and source rocks based on a comparison of the results of geochemical analysis with statistical analysis built upon machine learning methods: the case of one field of the West Siberian basin

The idea of this work is to compare the results of geochemical and statistical analyzes in the study of organic matter in extracts of oil and gas source rock. The object of the study were the samples of oil and gas source rocks of the Tutleim and Tyumen Formations, as well as oil samples of the Vikulov Formation and Jurassic and pre-Jurassic deposits in the western part of the West Siberian basin. Among the methods of statistical analysis, the principal component method and the random forest method were used. A heat map of correlations was used as visualization tools. The principal component method helped us to reveal a clear difference between the organic matter of the Tutleim and Tyumen source rocks. The random forest method and the heat map made it possible not only to identify the distinctive geochemical properties for this strata, but also reveals the geological factors of their distinction. Thus, the organic matter of Tyumen source rock turned out to be more mature and it has relatively larger contribution of terrestrial organic matter compared to the Tutleim one. The same set of methods is applied to oil-source rock correlation. The oils of the Vikulov Formation obviously originate from the Tutleim source rock. Oils of Jurassic and pre-Jurassic reservoirs have a predominant contribution of the Tutleim source rock and some similarity (up to 30 %) with the Tyumen one. Oils from the Vikulov Formations are less mature than oils from the Jurassic and pre-Jurassic rocks. This may indicate the continued migration of hydrocarbons to Jurassic and pre-Jurassic deposits and the cessation of migration in the past to the overlying Aptian–Albian Vikulov Formation. Geochemical analysis also revealed the geochemical properties responsible for the maturity of source rocks and the type of organic matter. It confirmed the conclusions made on the basis of the application of methods of statistical analysis.

Numerical study of the imaging capabilities of the pre-Jurassic complex of the Tomsk and Novosibirsk regions

Background and aim. The complexity of the structures of the Paleozoic deposits of Western Siberia requires the use of specialized methods for seismic data processing. However, the standard time processing procedures are still used in Western Siberia. Therefore, in this work, the goal is to study of seismic processing procedures for the construction of high-quality images of the pre-Jurassic complex in Western Siberia. 
 
 Materials and methods. A comparative analysis of time and depth processing was carried out in the paper on realistic synthetic data and models from Western Siberia containing the pre-Jurassic complex. Numerical examples are calculated for synthetic data obtained from two realistic seismic models. To create the first model, various geological and geophysical data from the Tomsk region are used. The most difficult areas of the Paleozoic in this model are steeply dipping carbonate structures and intrusive formations with steep slopes and outcropping to the erosion surface. Another model was built based on the seismic data processing results in the area of the Maloichskoye and Verkh-Tarskoye fields in the Novosibirsk region. Based on these data, the main horizons and a system of sub-vertical faults, characteristic of the pre-Jurassic deposits of the Novosibirsk region, were identified. Seismic data processing was carried out with an emphasis on the possibility of object-oriented migration. 
 
 Results. It is shown that the time processing of seismic data is insufficient and the need for deep processing to construct kinematically correct images of pre-Jurassic deposits. We also compared migration algorithms based on Gaussian beams and found that object-oriented migration gives the best quality results.

Oil and Gas Potential in the Territory of the South-Eastern Part of the Bukhara-Khiva Region

The article analyzes the oil and gas content of the southeastern part of the Bukhara-Khiva region. It is shown that this territory is the main promising target for prospecting for new oil, gas and hydrocarbon deposits. It was revealed that the main productive deposits are carbonate deposits. It has been established that the most widespread and large ones are massive deposits in traps of the structural-lithological type, confined to the Callovian-Oxfordian reef deposits and distinguished by high capacity and filtration properties. It is argued that the lower part of the reservoirs is flooded in all fields of this type. The characteristic is given of 44 open oil, oil and gas condensate, gas condensate and gas fields of the specified region. Pre-Jurassic deposits contain hydrocarbons. The features of the structural plans of carbonate and salt-anhydrite formations and their influence on the location of oil and gas deposits within the southeastern part of the Bukhara-Khiva region for increasing hydrocarbon reserves have been determined. The fields under development in the stage of deep drilling have been clarified. Recommendations for deepening geological exploration are offered.

POSSIBILITIES OF OBJECT-ORIENTED MIGRATION FOR IMAGING THE PRE-JURASSIC DEPOSITS

The paper presents the results of testing several migration procedures with an emphasis on the possibility of object-oriented imaging of the pre-Jurassic deposits. Numerical examples are calculated for synthetic data obtained for a realistic seismic model of pre-Jurassic deposits, built from real data from Western Siberia.

Oil and gas potential of the deep-lying Jurassic and pre‑Jurassic deposits of the North of Western Siberia in unconventional traps

In-depth additional studies were carried out to assess oil and gas potential of deep-lying Jurassic and pre-Jurassic deposits of the northern territories of Western Siberia. As in previous work, the geological and mathematical program “Vybor” was used. Based on the first constructed series of model maps with probabilistic values of informative geochemical and geological parameters, the most promising both local and regional objects were selected. Increasing complexity of the traps structure with depth was noted. As a rule, from the Cretaceous deposits to the Jurassic and Paleozoic, the type of trap from the predominant anticline (in the Cretaceous) changes to a much more complex combined one, which requires special approaches (and new technologies) to identify and explore such objects. Studies based mainly on seismic data indicate rather high oil and gas content of both the Paleozoic and Triassic deposits, which have a platform occurence and large thicknesses, as well as crystalline basement formations. In this regard, unconventional combined traps of deep-lying deposits of the North of Western Siberia are of significant interest in terms of incremental oil and gas resources and reserves.

On the nature of Paleozoic oil deposits and their exploratory "reflection" in the geophysical section of the Jurassic layers (southeast of Western Siberia)

Commercial significance of the majority of Western Siberian oil fields is concerned with the Senomanian, Neocomian and, above all, Upper Jurassic horizons. For now, oil fields are at the late development stage and resource potential of the Jurassic horizon is strongly expired. Commercial potential of the pre-Jurassic (Paleozoic) rocks has been brought out throughout all territory of oil and gas province. Extensive work on estimation of the pre-Jurassic rocks oil and gas potential is performed in southeast, in the territory of Tomsk Region, within which 13 hydrocarbon deposits have been discovered in the Paleozoic. Original hypothesis of anomalousness of geophysical and petrophysical characteristics of the Jurassic layers — uniqueness of «indication» the Paleozoic deposits in geophysical parameters of overlaying Mezozoic-Cenozoic section was stated as a foundation of new prospecting criterion for the Paleozoic deposits. The Paleozoic formations are accepted as a complex with its own oil generating potential, which results in upward migration of hydrocarbon fluids. Additionally, downward direction of vertical interstratal hydrocarbon migration from the Jurassic source rocks into the pre-Jurassic complex is brought out. It was accepted as a conception that as in case of upward, so in case of downward fluid migration, processes of superposed epigenesis perform and lead to secondary epigenetic transformations of rocks of transit Jurassic layers, which result in their anomalous geophysical and petrophysical characteristics. This paper analyzes and compares geophysical and petrophysical characteristics of the Jurassic layers of different field types in Tomsk Region: without oil and gas potential in pre-Jurassic section, with commercial inflows from the pre-Jurassic complex and unknown type. Results of exploration electrical resistivity and carbonatization in the Jurassic layers of 200 wells and also spontaneous potential variation, electrical resistivity and natural radioactivity in Bazhenov suite confirm anomalousness of geophysical and petrophysical parameters of Jurassic rocks in case of pre-Jurassic deposits. This paper determines 6 geophysical and petrophysical characteristics of the Jurassic layers as predictive indicators for oil and gas potential estimation in pre-Jurassic section. Efficiency analysis of using predictive indicators for bringing out fields with and without deposits in the pre-Jurassic complex was performed for different prospecting cases in the research territory with account taken of possible complexing of indicators, their rank and actual availability. This paper states preference of indicators complexing. Application of a new prospecting criterion will improve efficiency of searching in new prioritized stratigraphic horizon — the Paleozoic, which contains unconventional oil.

Comprehensive analysis for appraisal of oil and gas potential in the pre-jurassic part of the Ozen-Karamandybas field

Questions about the prospects for the oil and gas potential of the Paleozoic sediments of the Mangyshlak sedimentary basin remain open to this day, despite a long history of study and large volumes of research. This is primarily due to the imperfection of previously used prospecting and exploration technologies and the sufficiency of the discovered reserves of discovered deposits in the Mesozoic part of the section. Given the current situation of natural depletion of reserves in the Mesozoic sediments, there is a need to set up prospecting and exploration work in the deep horizons of the Paleozoic.
 The article provides general information about the study of the region, and on the basis of the proven facts of oil and gas content of individual areas and the latest drilling results obtained, raised the question of the oil and gas potential of pre-Jurassic deposits.

СОСТАВ БИОМАРКЕРОВ И ПРОИСХОЖДЕНИЕ НЕФТЕЙ АРЫСКУМСКОГО ПРОГИБА (ЮЖНЫЙ КАЗАХСТАН)

На основании данных анализа индивидуального состава биомаркеров нефтей из нижнего мела, нижней юры, палеозоя и протерозоя Арыскумского прогиба Южно-Торгайского нефтегазоносного бассейна реконструируются условия формирования нефтематеринских отложений, генерировавших нефти рассматриваемой территории. Исследование актуально для обоснования стратегии поисков нефтегазовых залежей с учетом тектоники фундамента Южного Казахстана. Цель: выявить сходство и различие состава нефтей залежей доюрскго фундамента и состава нефтей залежей в перекрывающих юрско-меловых осадочных толщах, определить особенности фациальных условий накопления нефтематеринского вещества на территории Арыскумского прогиба. Объекты и методы: нефти из нижнего мела, нижней юры, палеозоя и протерозоя Арыскумского прогиба Южно-Торгайского нефтегазоносного бассейна. Состав нефтей проанализирован методами газо-жидкостной хроматографии и хромато-масс-спектрометрии. Результаты и выводы. Определено распределение в нефтях и индивидуальный состав алканов, н-алкилбензолов, нафталинов, фенантренов, хейлантанов, пентациклических тритерпанов и стеранов, рассчитаны геохимические параметры, отражающие особенности условий формирования нефтематеринских отложений. Полученные данные продемонстрировали генетическое единство нефтей из нижнего мела и протерозоя Акшабулакской грабен-синклинали, а также единый генезис нефтей из нижнего мела и палеозоя Аксайской горст-антиклинали и отличие в фациальных условиях накопления нефтематеринских пород на этих территориях. В соответствии с данными о составе стеранов и пентациклических тритерпанов породы, продуцировавшие нефти в пределах Акшабулакской грабен-синклинали, отличаются повышенным содержанием карбонатов и накапливаются в более глубокой части моря и в менее окислительных условиях, чем на территории Аксайской горст-антиклинали, где нефтематеринская толща содержала больше глинистой составляющей и отлагалась, видимо, в условиях засоленной лагуны. Нефть из нижней юры Бозингенской грабен-синклинали генерирована отложениями, сформированными в опресненной дельтовой зоне.

ИЗОТОПНЫЙ СОСТАВ НЕФТЕЙ АРЫСКУМСКОГО ПРОГИБА (ЮЖНЫЙ КАЗАХСТАН)

Одним из обсуждаемых направлений в современной геологии является нефтегазоносный потенциал более глубоких горизонтов, в том числе фундамента осадочных бассейнов. Генезис залежей нефти является предметом острых дискуссий. Современные геохимические методы исследования вещества в совокупности с приборными возможностями, к которым можно отнести изотопный масс-спектрометр, позволяют различать нефти, генерированные разными нефтематеринскими отложениями. Важнейшим показателем, идентифицирующим генезис углеводородов по отношению к зонам нефтегазообразования в конкретном разрезе, является изотопный состав углерода. Каждая зона, в свою очередь, характеризуется индивидуальными геохимическими и термодинамическим параметрами, включающими тип и степень преобразованности рассеянного органического вещества, современные геотемпературы и палеотемпературные условия, фазовый состав углеводородов. Месторождения Арыскумского прогиба Южно-Торгайского нефтегазоносного бассейна (Южный Казахстан) связаны с различными литолого-стратиграфическими комплексами юрско-меловых отложений, девонско-нижнекаменноугольными образованиями квазиплатформенного комплекса и дезинтегрированными выступами фундамента. В последние годы перспективы Южно-Торгайского прогиба расширяются и связываются с доюрскими отложениями. В этой связи возникает вопрос о природе углеводородных масс и формировании их скоплений в мезозойских и домезозойских образованиях Арыскумского прогиба. Цель исследования: проведение сравнительного анализа изотопного состава углерода нефтей Арыскумского прогиба из мезозойских, палеозойские отложений, а также из зоны контакта палеозоя с мезозойским осадочным чехлом для решения генетических задач и выяснения особенностей формирования нефтяных месторождений Арыскумского прогиба. Результаты позволили установить закономерность изменения величины d13С в зависимости от возраста, глубины, территориальной приуроченности месторождений в пределах Арыскумского прогиба и на основании изотопных данных высказать предположение о генезисе мезозойских и домезозойских нефтей.

The heat flow, thermal history of the oil source Lower Jurassic Togurskaya suite and oil-and-gas potential of the Paleozoic of the Koltogor mezodepression(southern segment of the Koltogor-Urengoy paleorift)

Input of the pre-Jurassic («Paleozoic») oil is important to the reproduction of the in-situ resources base of Western Siberian oil and gas extraction. Prospecting and forecasting studies of the pre-Jurassic reservoirs in the territory of the Koltogor mezodepression and structures of its surrounding — in the north-western part of Tomsk Region, in the zone of the southern segment of the Koltogor-Urengoy Permian-Triassic paleorift are of interest. The pre-Jurassic oil and gas complex(oil and gas bearing horizon of the contact zone— OGBHCZ and, actually, the Inner Paleozoic) is assigned along with the Cretaceous (the Neocomian), Upper Jurassic, Middle Jurassic and Lower Jurassic oil and gas complexes in the study area. It is accepted that the Upper Jurassic Bazhenov suite is the oil source formation for the Middle Jurassic, Upper Jurassic and Cretaceous oil and gas complexes, as well as Togurskaya suite — for the Lower Jurassic and pre-Jurassic deposits. Researches are carried out in the context of the methodology of the sedimentary and migrational theory of naftidogenesis. Spatiotemporal localization of the generation foci of Togurskaya oil is performed with the original method of paleotemperature modeling. The heat flow in sections of 82 deep wells is calculated at the first stage of modeling. At the following stages the oil source suite geotemperatures are directly figured up in key moments of geological time. The integral express-assessment of realization of generation potential of the suite is performed on the base of calculated data about time of the oil source suite residence in the main oil generation zone and its geotemperatures. Vewing to the concept about predominantly vertical migration of hydrocarbons the forecasting is carried out in the outline of the oil source suite distribution. Schemes of distribution of Togurskaya oil accumulation density are built and zoning of deposits is performed taking into account the thickness and quality of potential reservoirs of the pre-Jurassic deposits. Oil geological zoning of the pre-Jurassic complex and ranking areas according to the degree of prospect abilities were accomplished. The most forward-looking zone for prospecting in the weathering crust reservoir is the area, which comprises the eastern part of the Cheremshanskaya mezzo saddle and its articulation with the northern side of the Koltogor mezodepression and the western slope of the Srednevasyuganskiy megaswell (in the order of 3500 km 2 ). The most optimistic forecast for the Inner Paleozoic reservoir is made for the same areas as for the weathering crust, less optimistic — for the Severo-Chkalovskiy incised valley and its articulation with the Murasovskiyhigh and Trassovoe dome-shaped uplift (in the order of 5700 km 2 ).Consistency of the forecast with established direct evidence of oil saturation amounts to 70 %. Detailed map of the heat flow density in the study area showed that the trench of the Koltogor-Urengoy graben-rift does not have significant manifestation in enhanced values of the heat flow. The article demonstrates methodological approaches and complex technology of zonal forecasting of oil and gas potential of the pre-Jurassic basement of Western Siberia, which are working out by Tomsk research school of Geothermy.

СРАВНИТЕЛЬНАЯ ПЕТРОФИЗИЧЕСКАЯ ХАРАКТЕРИСТИКА РАЗРЕЗОВ ГЕРАСИМОВСКОГО И КРАПИВИНСКОГО МЕСТОРОЖДЕНИЙ (В СВЯЗИ С НЕФТЕГАЗОНОСНОСТЬЮ ДОЮРСКИХ ОТЛОЖЕНИЙ)

Актуальность исследования обусловлена необходимостью воспроизводства сырьевой базы углеводородов юго-востока Западной Сибири за счет поисков и разведки залежей, приуроченных к доюрским отложениям. Цель: определить критерии прогнозирования и поисков палеозойских залежей углеводородов на основе изучения геофизического различия разрезов юрских отложений месторождений, как с палеозойскими залежами нефти, так и месторождений только с юрскими залежами нефти. Объекты: разрезы глубоких скважин Герасимовского нефтегазоконденсатного месторождения с основными запасами в пласте М – в проницаемых интервалах коры выветривания отложений палеозоя и скважин Крапивинского нефтяного месторождения, промышленная нефтеносность которого связана с терригенными отложениями юрского продуктивного горизонта Ю1. Методы: статистический анализ петрофизических параметров пластов-коллекторов по данным геофизических исследований скважин, оценка литологического состава коллекторов по петрофизическому критерию, сопоставительная оценка геофизической характеристики баженовской свиты Герасимовского и Крапивинского месторождений. Результаты. На примере геофизической характеристики разрезов 29 глубоких скважин Герасимовского месторождения и 34 скважин Крапивинского месторождения показано, что палеозойские залежи имеют уникальное «отражение» в геолого-геофизических параметрах перекрывающего мезозойско-кайнозойского осадочного разреза. Эта уникальность выражается существенно более высокими значениями удельного электрического сопротивления и карбонатизацией интервалов юрских отложений, а также отличительной характеристикой геофизических параметров интервала баженовской свиты. Для дальнейшей аргументации уникальности «отражения» залежей палеозоя в геофизических параметрах перекрывающих отложений, как критерия прогнозирования и поисков палеозойских залежей УВ, предлагается провести аналогичные исследования на нескольких месторождениях как герасимовского, так и крапивинского типов.