Development Of Hydrocarbon Resources Research Articles

Geomagnetic support for directional drilling

The high-tech directional drilling (DD) procedure for the development of hydrocarbon resources requires high precision positioning of the drill string. Such accuracy can be achieved by navigation based on the Earth’s magnetic field (EMF), which ensures hitting a given target with an error of 3 m at a distance of 15 km. However, the EMF is characterized by multi-scale variability both in space and time. Therefore, the full stack of DD geomagnetic support includes a detailed, real-time estimation of the EMF spatio-temporal variability in the deposit region and geomagnetic activity forecast. Particularly strict control of a drill string orientation is required when drilling in the Arctic region. The article is devoted to modern technologies for effective accounting of the features of the EMF space-time structure to ensure precise navigation of the drill string. The paper is based on the report delivered at the RAS Presidium meeting on 11 June 2024.

Problems of Arctic Hydrocarbon Development in The Context of Modern Global Challenges: Development Potential and Industry Strategies

Significant hydrocarbon raw material potential in the Arctic territories and complex technological solutions for its development dictate the need to solve extraordinary organizational, managerial and technical tasks of strategic nature. There are economic difficulties associated with oil and gas production in the Arctic fields and, in particular, in the development of offshore facilities. The article focuses on the sectoral strategies of oil and gas complex development, which should be balanced with regional and corporate strategies. Industry strategies for the development of the Arctic oil and gas complex detail a specific set of measures that fully reflect the technological and economic capabilities of domestic companies, it is especially important to assess the achievability of strategic goals in terms of the development of offshore resources. The purpose of this study is to summarize the strategic problems of the development of hydrocarbon resources in the Arctic with the identification of options for the development strategies of oil and gas industry complexes. The methodology of the research is based on the methods of strategic management. Within the framework of solving strategic problems and tasks, it is advisable to apply various scenarios using the methods of strategic alternatives, and, in particular, matrix methods. Matrix methods allow to use the results of the analysis and offer specific alternatives that can be used as a basis for strategic choice in the development of sectoral strategies of the oil and gas complex. The scientific results of the study are determined by the generalization of the problems of the Arctic hydrocarbon potential development and the development of alternative strategy options for solving technological and environmentally-oriented strategic problems. The article presents strategic problems of Arctic oil and gas fields development. The key economic, organizational, technological, social, environmental and geo-political problems are highlighted. Technological strategies largely depend on markets and the policy of technological sovereignty. Using domestic markets or turning to external markets seems to be an important strategic choice, as it determines the level of investment costs — in-house development or purchase of technologies on open markets. For the development of breakthrough technologies in offshore hydrocarbon production, it is possible to rely on the domestic technology market to develop new technical solutions and digital systems. Environmentally-oriented strategies are based on sustainability and efficiency criteria with economic or socio-environmental aspects being prioritized. It is revealed that “green” strategies can take place, but for the development of oil and gas industrial complexes it is important to maintain a balance between production development and environmental safety.

Factor analysis-based deep differentiation of oil deposits in the Ural-Volga region

The purpose of the article is to present an algorithm developed on the scientific and methodological foundations of quantitative and qualitative processing of geological and commercial data to implement the procedure for deep identification of deposits. The developed algorithm consists of two levels: the initial stage includes facility identification by tectonic and stratigraphic characteristics resulting in the formation of a number of megagroups of objects. Then they are subjected to deep differentiation using the elements of data factor analysis, which is carried out together with the monitoring of the highly identical objects. The presented approach to solving the problems of field effective grouping is the most effective due to a comprehensive and reasonable assessment of the groups of facilities formed as a result of modeling. The developed algorithm was tested on example of a number of fields associated with terrigenous reservoirs of the Devonian and carboniferous systems of the Volga-Ural oil and gas province. After two calculation stages the percentage of correctly grouped objects averaged 96.8 %, which is a high result. To make the search for analogous objects qualitative and objective eighteen equations have been obtained that combine twenty parameters describing the geological and physical characteristics of productive formations as well as the physico-chemical properties of the fluids saturating them at the sufficient level of reliability. Based on the results of using the developed algorithm for deep identification of deposits, the authors obtained a number of relevant mathematical dependencies between various parameters, graphical distributions of objects in the axes of the main components, which all together enable efficient and systematic search for analogous objects in the deposits of terrigenous reservoirs of the Devonian and carboniferous systems of the Volga-Ural oil and gas province. Besides, the presented identification diagrams enable successful management of the processes of oil recovery within the micro- and macro-levels of facility distribution in the axes of the main components. They also allow to form a list of general recommendations that will contribute to the optimal development of liquid hydrocarbon resources.

Microscopic pore-throat structure variability in low-permeability sandstone reservoirs and its impact on water-flooding efficacy: Insights from the Chang 8 reservoir in the Maling Oilfield, Ordos Basin, China

The Chang 8 reservoir of the Maling Oilfield in the Ordos Basin, China is facing a series of challenges in hydrocarbon resource development, including rapidly decreasing production rates, declining dynamic fluid levels, and elevated water cuts in oil wells, along with heterogeneity in microscopic pore-throat structures and notable interstratal inconsistencies. To systematically address these issues, this study selected representative samples from the reservoir and conducted rigorous microscopic percolation experiments on them. A comprehensive evaluation of the heterogeneity in microscopic pore structures was conducted using an integrative methodological approach, involving physical property quantification, petrographic thin-section analysis, scanning electron microscopy, constant-rate mercury intrusion, and nuclear magnetic resonance techniques. The primary objective of this investigation is to elucidate the underlying formation mechanisms, states of occurrence, and spatial distributions of residual oil. Understanding of these issues will facilitate the establishment of empirical correlations between diverse microscopic pore structures and water-flooding efficiencies, and aid in the identification of key variables governing the distribution of residual oil. Analytical outcomes reveal substantial variations in seepage characteristics contingent upon the nature of microscopic seepage conduits. Specifically, the Chang 8 reservoir manifests four discernible categories of microscopic seepage pathways: solely intergranular pores, a confluence of dissolution and intergranular pores, exclusively dissolution pores, and micropores. A correlative decline in oil displacement efficiency is observed across these conduit types. Critical variables such as throat radius and its distribution patterns emerge as pivotal determinants influencing oil displacement efficiency, eclipsing the impact of conventional physical properties and mobile fluid saturation levels. Remarkably, samples characterized by a composite of dissolution and intergranular pores demonstrate superior displacement efficiency. Distinct types of pore structures correspond to noticeably different water-flooding oil pathways and oil displacement efficiencies. During the water-flooding process, fingering network displacement is dominant, and it exerts a significant control on oil displacement efficiency. Key factors affecting this efficiency include the injected water volume multiples and displacement pressure, values of which should be optimized during the actual water-flooding process.

Development of the Oil and Gas Potential of the Arctic Region: Issues of Methodology and Practical Implementation

In the development of methodological provisions for the integrated development of hydrocarbon resources are considered issues of improving the subsoil use of the Arctic and continental shelf of Russia. State support measures provide for the introduction of advanced technological solutions, that meet the highest environmental requirements, in all stages of the production processes of oil and gas enterprises. The application of various methodological tools to shelf projects taking into account internal specifics are justified. This contributes to formation of oil and gas centers in the Arctic region, becoming of the Northern Sea Route as a global transport route. The key areas of practical implementation of the state Arctic policy are related to the solution of infrastructure, logistics and socio-economic issues in the Arctic regions, the development of related industries. Strengthening the energy potential of the region provides the adoption of verified state and management decisions, the creation of special legal conditions for the integrated development of oil and gas fields, aimed at stimulating internal mechanisms of economic growth, preserving the unique ecosystem and biological diversity in the Arctic. To a certain extent, this is facilitated by the cluster form of development, the involvement of the largest scientific and industry institutions in the implementation of Arctic projects, which leads to improving professional competencies, and the implementation of a flexible technological policy. The complex development of hydrocarbon reserves of the Arctic and continental shelf makes a significant contribution to the achievement of technological sovereignty of the domestic economy and the advanced technological development of the oil and gas complex.

Prospects for the arctic shelf development

Nowadays development of the Arctic shelf and the continental slope resources is one of the most promising areas in the world oil and gas industry growth. Russia, unlike other countries with Arctic hydrocarbon reserves, implements only a few projects on the Northern shelf due to the difficult natural and climatic conditions and ecological vulnerability of the territory. The purpose of the article is to substantiate the feasibility of hydrocarbon resources development on the Russian Federation Arctic shelf in the long term. The article analyzes the external and internal factors affecting the decline in the rate of oil and gas exploration and production in this region in recent years. It considers state support measures reflected in the Strategy for the Russian Arctic Zone Development and Ensuring National Security – 2035, and a number of other laws and regulations developed and adopted after 2014. Special attention is given to the development of high-tech imports phase-out; specialists training; science, education and business integration; reducing the tax burden; environmental issues. The tasks facing state authorities, oil and gas companies, scientific and educational organizations have been identified that will lead to the successful Arctic shelf reserves development.

Control of strike-slip faults on Sinian carbonate reservoirs in Anyue gas field, Sichuan Basin, SW China

The largest Precambrian gas field (Anyue gas field) in China has been discovered in the central Sichuan Basin. However, the deep ancient Ediacaran (Sinian) dolomite presents a substantial challenge due to their tightness and heterogeneity, rather than assumed large-area stratified reservoirs controlled by mound-shoal microfacies. This complicates the characterization of “sweet spot” reservoirs crucial for efficient gas exploitation. By analyzing compiled geological, geophysical and production data, this study investigates the impact of strike-slip fault on the development and distribution of high-quality “sweet spot” (fractured-vuggy) reservoirs in the Ediacaran dolomite of the Anyue gas field. The dolomite matrix reservoir exhibits low porosity (less than 4%) and low permeability (less than 0.5×10−3 μm2). Contrarily, fractures and their dissolution processes along strike-slip fault zone significantly enhance matrix permeability by more than one order of magnitude and matrix porosity by more than one time. Widespread “sweet spot” fracture-vuggy reservoirs are found along the strike-slip fault zone, formed at the end of the Ediacaran. These fractured reservoirs are controlled by the coupling mechanisms of sedimentary microfacies, fracturing and karstification. Karstification prevails at the platform margin, while both fracturing and karstification control high-quality reservoirs in the intraplatform, resulting in reservoir diversity in terms of scale, assemblage and type. The architecture of the strike-slip fault zone governed the differential distribution of fracture zones and the fault-controlled “sweet spot” reservoirs, leading to wide fractured-vuggy reservoirs across the strike-slip fault zone. In conclusion, the intracratonic weak strike-slip fault can play a crucial role in improving tight carbonate reservoir, and the strike-slip fault-related “sweet spot” reservoir emerges as a unique and promising target for the efficient development of deep hydrocarbon resources. Tailored development strategies need to be implemented for these reservoirs, considering the diverse and differential impacts exerted by strike-slip faults on the reservoirs.

Comprehensive analysis of stress magnitude and orientations and natural fractures in complex structural regimes oil reservoir: Implications for tectonic and oil field development in the Zagros suture zone

Complex structures with different stress regimes pose challenges in tectonic studies and have implications for the oil and gas industry. The analysis of in-situ stress state and natural fractures in the Dezful Embayment, the southwestern part of the Zagros fold and thrust belt (ZFTB) in Iran, and their implications for tectonic and oil field development are poorly understood. This study analyzes stress orientations, natural fractures, pore pressure (Pp), and stress regime in two oil fields located in the Zagros foothills. The study utilized various data types, including image logs and conventional logs, to determine the in-situ stresses and their implications for energy field development. The results show that the mean orientations of the maximum horizontal stress SH in Field A and Field B are N32°E and N55°E, respectively. The analysis of natural fractures indicates that most tensional fractures are subparallel to the orientation of the maximum horizontal stresses, and the present stress state is responsible for these fractures. The analysis of stress magnitudes demonstrates that the stress regime in Field A changes from thrust faulting toward strike-slip faulting in deeper intervals below water-oil contact. The findings provide valuable insights into the region's reservoir development plans and seismic activities. The orientation of natural fractures suggests that horizontal wells drilled parallel to the orientation of SH can optimize wellbore stability. In addition, the stress variations and complexities observed in Field A are attributed to factors such as folding degree, lateral deformability contrasts, and geological structures like faults. The stress regime analysis indicates the influence of regional tectonic forces and the proximity to the collision boundary. This study will provide valuable insights into the exploration, development, and management of hydrocarbon resources in complex structure regions such as the Dezful Embayment, and it may contribute to understanding stress variations and distribution patterns in similar geological settings elsewhere.

Sedimentological, Diagenetic, and Sequence Stratigraphic Controls on the Shallow to Marginal Marine Carbonates of the Middle Jurassic Samana Suk Formation, North Pakistan

This study presents a thorough analysis of the sedimentology, diagenesis, and sequence stratigraphy of the Middle Jurassic Samana Suk Formation in the Hazara Basin of northern Pakistan. Focusing on two sections, namely Mera Rehmat and Por Miana, the research aims to unravel the complex geological processes within the formation. The examination of microfacies reveals nine distinct depositional textures, ranging from mudstone to wackestone, packstone, and grainstone, indicating various inner ramp environments such as open marine, lagoon, and coastal settings. Petrographic investigations shed light on diagenetic processes, including micritization, cementation, dissolution, compaction, neomorphism, and dolomitization. Six cementation types are identified, and the dolomitization patterns vary, providing insights into lagoonal environments and mudstone replacement. Sequence stratigraphic analysis uncovers intriguing patterns within the Samana Suk Formation. The high-stand system tract is characterized by mudstones, pelloidal grainstones, and dolomitized mudstones, indicating periods of high sea level. In contrast, the transgressive system tract displays ooidal grainstones, pelloidal packstones, and pel-bioclastic grainstones, representing transgression and inundation of previously exposed areas. A significant finding is the impact of diagenesis on reservoir quality parameters, specifically porosity, and permeability. Diagenetic processes, cementation types, and dolomitization patterns have significantly altered the pore network, highlighting the importance of considering diagenesis in assessing the Samana Suk Formation as a hydrocarbon reservoir. This research provides a comprehensive understanding of the sedimentology, diagenesis, and sequence stratigraphy of the Middle Jurassic Samana Suk Formation. The findings contribute to our knowledge of similar carbonate reservoirs globally, enhancing the exploration and development of hydrocarbon resources in comparable depositional environments.

The Practice and Development of T-Bar Penetrometer Tests in Offshore Engineering Investigation: A Comprehensive Review

In recent years, the development of marine hydrocarbon resources has led to an increased demand for research on the marine soil bearing capacity and cyclic loading effect in marine engineering design. Because of the difficulties and high costs involved in obtaining high-quality soil samples from offshore sites, in situ testing techniques have become the preferred method of determining design parameters in offshore geotechnical engineering projects. This paper provides a review of the current state of marine penetrometer deployment technology used in offshore engineering investigations and presents a summary of the T-bar penetrometer test for measuring marine soft clay. The existing literature research on penetration mechanisms, numerical simulations, laboratory experiments, and field tests of the T-bar penetrometer in the field of marine geotechnical engineering are analyzed. Finally, the potential difficulties, challenges, and prospects of the T-bar penetrometer tests are discussed.

The Gas Pandemic in the Eastern Mediterranean Region

The article deals with the role of hydrocarbon resources in the Mediterranean Sea. The discovery of oil and gas deposits in this region in recent decades has significantly increased its role in the energy security of Europe. Due to the transformation of the world energy map, the Mediterranean region has been the focus of attention of many European states. At the same time, a large number of projects on promising fields, as well as the laying of new oil and gas pipelines have been developed. The implementation of many pipeline projects can dramatically change the European gas market, which is of great interest to many countries In addition, the European gas market is under extreme pressure because of the supply of liquefied natural gas, and its volume is gradually increasing. This means that in the long term the development of hydrocarbon resources can significantly enhance the role of the Mediterranean and affect the development of the European oil and gas market.

MATERIALS AND ANTICORROSION DEVELOPMENTS IN OFFSHORE AND SUBSEA OIL AND GAS PRODUCTION

The development of hydrocarbon resources of the continental shelf of the Russian Federation and especially its Arctic part and the Far East is the largest infrastructure project based on unique proven oil and gas reserves. The continental shelf of Russia is a large national hydrocarbon reserve, which can provide up to 25% of Russian oil and up to 30% of Russian gas. The most difficult reserves represent difficult development conditions - high pressure and low temperatures, may be in deep water or arctic regions. As oil resources become more and more heterogeneous, an expansion of various methods of extraction and processing is required, including in extreme conditions, at high pressures in aggressive marine environments and low temperatures. An integrated field development method allows maintaining a high level of hydrocarbon production for a long time, reducing costs by optimizing the resources used and using a common infrastructure. In the long term, the presence of production facilities and service bases near the Arctic shelf will allow solving multidisciplinary tasks that affect various segments and areas, such as engineering and technology, environmental protection, and others. The review article discusses the factors affecting the resistance of oil and gas pipelines to corrosion in the marine environment, the issues of hardening and alloying corrosion-resistant alloys for use in the marine and underwater environment while expanding the boundaries of the use of traditional technical alloys, as well as further study of the mechanisms of corrosion and crack propagation, which can lead to equipment failure and destruction. The study of nanoscale corrosion analyzed in this article can have a profound impact on the degradation characteristics of materials applicable to the entire industry.

Physics-informed graph neural network for spatial-temporal production forecasting

Production forecast based on historical data provides essential value for developing hydrocarbon resources. Classic history matching workflow is often computationally intense and geometry-dependent. Analytical data-driven models like decline curve analysis (DCA) and capacitance resistance models (CRM) provide a grid-free solution with a relatively simple model capable of integrating some degree of physics constraints. However, the analytical solution may ignore subsurface geometries and is appropriate only for specific flow regimes and otherwise may violate physics conditions resulting in degraded model prediction accuracy. Machine learning-based predictive model for time series provides non-parametric, assumption-free solutions for production forecasting, but are prone to model overfit due to training data sparsity; therefore may be accurate over short prediction time intervals.We propose a grid-free, physics-informed graph neural network (PI-GNN) for production forecasting. A customized graph convolution layer aggregates neighborhood information from historical data and has the flexibility to integrate domain expertise into the data-driven model. The proposed method relaxes the dependence on close-form solutions like CRM and honors the given physics-based constraints. Our proposed method is robust, with improved performance and model interpretability relative to the conventional CRM and GNN baseline without physics constraints.

Distribution and occurrence of pore water and retained oil in nanopores of marine-terrestrial transitional shales during oil generation and expulsion: Implications from a thermal simulation experiment on shale plug samples

The distribution and occurrence of pore water and retained oil in shale nanopores is a key scientific issue confronting the evaluation, exploration and development of shale hydrocarbon resources. At present, however, relevant researches are scarce, especially on marine-terrestrial transitional (MTT) shales. In this study, a thermal simulation experiment was performed on a set of water-saturated shale plug samples prepared from a low-maturity MTT shale. The pore water and retained oil contents of the artificially matured samples were quantified, and the pore structures under moist, dried, and solvent extracted conditions were investigated. The results show that the pore water content of the shale decreases with Ro increasing from 0.75% to 0.97% and then increases with Ro further increasing to 1.53%, which exhibits a negative correlation with the retained oil content during the oil generation and expulsion. The pore water occurs mainly in filling, adsorption and water-cluster states in micropores (<2 nm), small non-micropores (2–10 nm), and large non-micropores (>10 nm), respectively. The retained oil is mainly in a filling or dissolved state in the micropores and small non-micropores and in an oil-cluster state in the large non-micropores. The pore water and retained oil in shale micropores are stored in the inorganic matter (IM) and organic matter (OM) micropores, respectively. During oil generation and expulsion, the IM micropores are fully saturated by the pore water that is barely expelled, and most of the pore water is stored in non-micropores, especially in large non-micropores. With increasing maturity, the distribution of retained oil in nanopores changes obviously. The retained oil in non-micropores tends to be stored in the large non-micropores at low-maturity stages, occurs uniformly in both the small and large non-micropores at mature stages, and is dominantly reserved in the small non-micropores and micropores at high-maturity stages. These results have significances for understanding the accumulation mechanism of shale oil and gas resources under geological conditions and evaluating their resource potential.

Россия и Иран на Южном Кавказе: проблемы и перспективы сотрудничества в сфере энергетической безопасности

Introduction. In the context of the complex geopolitical situation that has developed in the South Caucasus in the post-Soviet period, the problems associated with the security of this region have become much more complicated. Among them, an important place was occupied by issues of energy security, the solution of which increasingly depended on the political phenomena and processes taking place in the South Caucasus. The importance of studying this sphere of regional relations, which has become the focus of research attention, has increased. Of particular interest is the study of the role and place of Russia and Iran in regional relations in the South Caucasus, their participation in solving energy problems, which turned out to be among the current priorities of their policy in the South Caucasus direction. Materials and methods. The paper analyzed the publications of domestic and foreign researchers devoted to the problems of regional security in the South Caucasus. Documentary materials were involved, reflecting the rivalry of the leading Western countries with Russia and Iran for economic positions in the region, in particular, the development of hydrocarbon resources of the Caspian Sea and routes for their delivery to Europe. The work used problem-chronological, comparative and systemic methods to identify the degree of study of issues related to energy security in the South Caucasus. Analysis. The article specifies the factors influencing the energy policy of Russia and Iran in the South Caucasus, reveals their approach to solving complex issues that have accumulated in the energy sector. It is proved that in the course of a constructive dialogue between the two countries, favorable conditions were created for the development of strategic partnership in the South Caucasus. Results. The paper concludes that the resistance of the United States and its Western allies to the interests of Russia and Iran in the South Caucasus resulted in their wish to strengthen partnerships, strengthen the joint struggle against Western influence in the region and create conditions for its peaceful, safe and stable development.

ОСВОЕНИЕ НЕФТЕГАЗОВЫХ МЕСТОРОЖДЕНИЙ В ИНТЕРЕСАХ РЕАЛИЗАЦИИ ПРИОРИТЕТОВ СОЦИАЛЬНО-ЭКОНОМИЧЕСКОГО РАЗВИТИЯ РОССИЙСКИХ АРКТИЧЕСКИХ РЕГИОНОВ

The article considers issues related to industrial development of hydrocarbon resources of the Arctic territories of Russia in the context of socio-economic significance. The purpose of the research is to analyze the factors of influence of the implementation of oil and gas projects on the socio-economic development of regions, taking into account the transition to the domination of resource-innovative economic model, with priority of social interests. The conducted study justifies the need for an active public policy, based on comprehensive and systematic solutions to the problems of organizing the rational use of the existing resource potential of the Arctic zone of the Russian Federation, on the basis of linking economic, innovative, social and environmental factors, taking into account well-defined and structured benchmarks. It was noted that in order to achieve high indicators of development of the Arctic zone of the Russian Federation, to improve the level and quality of life of the population, to increase the production and technical potential, to replenish financial regional resources, environmental protection requires the targeting of oil and gas projects aimed at ensuring the priority of social and economic values. The urgency of the application of integration and cooperation in related sectors of economy on the basis of advanced scientific achievements and innovations has been established, a prerequisite for industrial companies to achieve social security and improve human habitats is the practice of corporate social responsibility.

Putin’s War in Syria: Russian Foreign Policy and the Price of America’s Absence

Putin’s War in Syria: Russian Foreign Policy and the Price of America’s Absence

Lift the veil of secrecy in sub-resolved pores by Xe-enhanced computed tomography

The efficient development of tight hydrocarbon resources based on the proper understanding of rock properties can be underlined as a game-changing scenario of the energy market during the coming years. Digital Rock Physics (DRP) is an advanced technique for the accurate assessment of formation properties with respect to the effects of pore structures. However, there are doubts about the usefulness of DRP for tight systems where a large portion of pores are sub-resolved, and subsequently, their effects on numerical computations cannot be taken into account. By taking advantage of Xenon-enhanced computed tomography and nano-scale imaging, the current research puts forward a hybrid workflow that reveals sub-resolved pores and assigns them a proper set of petrophysical properties that can be used for further numerical simulations. The introduced method was applied to a tight sandstone sample. Conventional micron-scale x-ray computed tomography images show no connectivity of the porous space. That is why computation of permeability is impossible. The developed workflow created a three-substance media including pores, solids and submicron porous segments. The triple reconstructed porous media allows introducing the Stokes–Brinkman equation to simulate flows. The results indicated that the computed permeability is reasonably close to the experimental value. The main advantage of the launched method is that the computations achieved satisfying results without increasing the spatial resolution of images or limiting the field of view. • Xe-enhanced computed tomography is applied to analyse sub-resolved pores. • A hybrid algorithm of image processing to build a multiscale rock model is shown. • Stokes–Brinkman equation is taken to compute the permeability of the digital model.

Hydrocarbon regulation and lower temperature pyrolysis of balikun oil shale kerogen

Oil shale kerogen is a kind of composite nature of fossil energy polymer. Kerogen pyrolysis is a feasible and alternative strategy to produce fossil fuels from shales. However, the disadvantages including the high energy consumption, the high cost, and the low hydrocarbon conversion, significantly hinder the development and utilization of unconventional hydrocarbon resources. Herein, the hexagonal crystal structural layered double hydroxides (LDHs) with the Ni/Fe ratio of 5.64:2.36 is proposed as pyrolysis catalyst to improve the catalytic efficiency, the selectivity of target hydrocarbons, and lower the temperature for the process of kerogen pyrolysis. As a result, needle-like nanoscale NiFe-LDHs are prepared successfully to perform the fast thermal upgrading of Balikun oil shale kerogen. The catalytic pyrolysis performance has been observed that the temperature for maximum conversion (Tmax) is 401.18 °C, presenting a Tmax reduction of 37.84 °C, the yield of shale oil is increased by 7.83 wt%. And during 350°C– 400°C, a progressive increment of 147.67%, 230.86%, and 310.61% is obtained corresponding to the content of C1-C5, C6-C14, and C14 + hydrocarbons, respectively. This finding enriches the catalyst candidates for kerogen pyrolysis and provides new insights into industrial applications of in-situ pyrolysis technology for oil shale recovery processes.

Numerical simulation on proppant migration and placement within the rough and complex fractures

Hydraulic fracturing is a key technology for the development of unconventional hydrocarbon resources. The proppant placement morphology determines the fracture conductivity, thus affecting the reservoir stimulation effect. In this paper, the proppant migration and placement within complex fractures was studied by considering the fracture wall roughness through computational fluid mechanics-discrete element method (CFD-DEM) in numerical simulation, which is a key approach to study the proppant migration and placement. The results show that the proppant placement non-uniformity, proppant migration capacity, and proppant volume filled in the far-end and the secondary branched fracture are enhanced within the rough fracture compared with those within smooth fractures. The proppant migration capacity is increased within the fracture at low inclination angles (<60°) and low approach angles (<90°), and the proppant placement area is larger in the inclined fracture than that in the vertical fracture. The rise of injection rate and fracturing fluid viscosity causes more proppants migrate to far-end or secondary fractures, resulting in a non-proppant area within the near-wellbore fracture. An increase by 1.3 times in the injection rate and 3 times in the fracturing fluid viscosity leads to a decrease by 26.6% and 27%, respectively, in the proppant placement area within the near-wellbore fracture. The staged injection with small size proppants followed by large size proppants increases the proppant placement area in the primary fracture by 13%–26%, and that with large size proppants followed by small size proppants increases the proppant placement area by 19%–25%, which is due to that the latter method facilitates filling of the secondary branched fracture. The injection location mainly affects the proppant filling degree within the near-wellbore fractures. Compared with the upper injection, the middle and lower injection is not beneficial to filling of proppants within the near-wellbore fracture.