Rock Parameters Research Articles (Page 3)

Numerous measurements show that after a strong earthquake the velocity of seismic waves changes and then slowly returns to its original value. The relaxation process can last from several months to several years, while the seismic wave velocity often changes logarithmically with time similar to what was observed in laboratory experiments. In this work, the relevant experimental results, including long-term observations at the Parkfield Seismic Observatory (California), are analyzed using the previously developed physical model that was successfully used to describe "slow time" effects in laboratory experiments. The model is based on an Arrhenius-type equation describing the evolution of contacts between grains and in cracks. The results of simulations of the recovery time are in satisfactory agreement with the experimental data. These results may be used for remote diagnostics of rocks' stress state.

As an important geological environment medium for engineering construction in southwest China, basalt generally contains hidden microcracks at a micro-scale, which leads to significant size effect on its mechanical properties, and relevant research is lacking and unsystematic. A synthetic rock mass model based on the combination of a micro-discrete fracture network method and a finite-discrete element method is used to systematically explore the size effect of the mechanical properties of basalt rock blocks with hidden microcracks. The results showed that: (1) the fracture angle is uniformly distributed, and the fracture length conforms to the logarithmic normal distribution, with an areal fracture intensity P20 of 0.00025/mm2 and P21 of 0.012 mm/mm2. (2) According to the variation trends of mechanical parameters with the increase in the specimen dimension, the REV size of basalt rock blocks with hidden microcracks is determined to be 0.5 m. The mechanical properties obtained at this size are considered equivalent continuum properties and could be used as input parameters of rock blocks in complete rock mass or jointed rock mass for the numerical analysis at an engineering scale. (3) With the increase in the sample dimension, basalt changes from a small-sized complete sample to a medium-sized sample with local defects and then to an REV-sized sample with sufficient defects, the stress–strain curve characteristics under Brazilian disc splitting change from a single-peak shape to a zigzag shape and then to a multi-peak shape, and the failure modes changes from a single-center splitting failure mode to a local structure-controlled failure mode and then to a multi-center splitting failure mode, with the gradual decrease in the brittleness degree. The research results further enrich and improve the basic theory and technical methods of multi-scale analysis of geotechnical engineering, and provide strong scientific and technological support for the safety construction of deep engineering.

This study focuses on the complex stress distribution in coal seams influenced by normal fault using the fault development zone of the LF-M1 oilfield in southern China as a case study. Based on 3D seismic and drilling data, a key research area was delineated, and strata were reclassified considering rock parameter similarity. An FLAC3D model encompassing hanging wall, normal fault, and footwall strata was developed to systematically analyze geostress near the fault under various conditions. The results indicate that the normal fault induces non-uniform and discontinuous stress patterns in the coal seam’s transverse plane. Stress weakening occurs near the fault, with a pronounced concentration on its flanks, approaching in situ stress levels in the far field. Coal’s Poisson’s ratio, elastic modulus, and fault dip negatively correlate with horizontal in situ stress, whereas other parameters show positive correlations. The maximum horizontal stress is more sensitive to parameter variations than the minimum. Stress weakening is most influenced by coal’s Poisson’s ratio, followed by coal’s elastic modulus, fault elastic modulus, fault Poisson’s ratio, fault dip, and fault thickness and the coal seam thickness. Notably, a 20% decrease in coal’s Poisson’s ratio leads to a 23.32% stress reduction at measuring point 1. Conversely, the coal seam thickness has a minimal impact on stress across the fault. When the coal seam thickness increases by 20%, the maximum horizontal stress at measuring point 2 only decreases by 0.06%. In summary, fault geometry, rock mechanics parameters, and external loads collectively complicate stress distributions near faults, posing risks of drilling accidents such as wellbore instability, leakage, and reservoir damage, necessitating careful consideration.

ABSTRACTWhile rocking systems are increasingly researched and developed as a promising approach to achieving seismic resilience, several studies have identified the unpredictability of their dynamic response as an obstacle to their wider adoption. Despite a significant body of literature which has identified and studied the chaotic behaviour of unenhanced rocking frames, other studies have shown that practical applications of controlled rocking systems demonstrate a more predictable response that is similar to that of more conventional yielding systems. This paper examines the differences between these two bodies of work and identifies parameters shown to improve rocking predictability. Subsequently, a perturbation study conducted on a controlled rocking podium system subjected to historic ground motions is employed to study the influence of each parameter on the predictability of such systems. The results reveal that adding supplemental damping, increasing the contribution of the superstructure properties on the rocking system behaviour and limiting the rocking rotation effectively reduce the sensitivity of rocking systems to perturbations in the rocking parameters. In addition, adding auxiliary stiffness was found to be a viable method to improve the stability of these systems but did not significantly enhance predictability.

This paper proposed a fracture propagation model of water-based fracturing based on seepage–stress–damage coupling, which was employed to analyse the effects of different water-based fracturing fluid properties and rock parameters on the propagation behaviour of reservoir fractures in low-permeability reservoirs. Concurrently, molecular dynamics theory and mechanical analysis of reservoir fractures were employed to elucidate the microscopic mechanism of water-based fracturing on fracture propagation. The results showed that the apparent viscosity of water-based fracturing fluid primarily contributed to elevated fracture internal pressures through the seepage reduction in water-based fracturing fluid at the coal fracture surface. A substantial impact on the minimum fracturing pressure of coal fractures that rapidly pierce the coal rock and an increasing crack extension was notably presented by the low filtration and high viscosity of water-based fracturing fluids. Furthermore, the reservoir pressure and the crack turning angle were not conducive to the effective expansion of coal seam fractures, whereas the reservoir temperature exhibited a positive proportional relationship with deep coal seam fractures.

One of the principal challenges of the current and next century’s environmental, scientific, and technical areas is undoubtedly the exploration of carbonate rocks. The role of in-depth understanding and extensive knowledge of subsurface in petroleum exploration and production is undeniable. This industry has been furnished with much information regarding the petroleum industry due to technological development. However, as a result of the nature of the subsurface many uncertainties exist that need to be addressed. Recently, the aforementioned uncertainties have been dealt with by the potential tools provided by investigating the effective parameters such as facies, diagenesis, fractures, and sedimentary environment. Some topics of investigation are recommended in the form of research questions. One question is as follows: What are the research gaps and prospective research directions for carbonate rock exploration? Previously proposed hydrocarbon content determination models in carbonate rocks have raised questions due to the complicated systems and inherently heterogeneous nature. The key purpose of this article is to deeply review the literature to find the exploration paradigms of carbonate rocks, to evaluate the existing models for their prediction in carbonate rocks of different types, and to shed light on the future routes of such studies. For this purpose, the articles presented in different databases from 1960 to 2022 have been reviewed. In the present study facies, fracture, sedimentary environment, and diagenesis parameters have been considered as the criteria for the article selection. To provide the researchers with meritorious assistance to develop a deep knowledge of carbonate rock exploration paradigms in new settings and to develop more effective deployment approaches, the proposed concept map has been prepared. It should be noted that despite the direct relationship generally observed between permeability and porosity, in practice it is not possible to develop the same general relationship for porosity and permeability because the controlling parameters of carbonate rocks vary significantly in each field and formation. Therefore, by examining the logs of several wells and interviewing experienced employees of the oil company about the case study oilfield, they concluded that the contribution of porosity was not considerable and that fracture in production is more effective than vugs or decent porosity. The porosity obtained from the total field logs was 4% and its permeability was obtained from the core and with the help of equations and fracture models.

The dynamic and static elastic parameters of rocks exhibit differences. It is of great practical significance to carry out experiments on dynamic and static elastic parameters of rocks under reservoir conditions and determine the conversion relationship between dynamic and static elastic parameters. In this study, shale oil samples from the second member of Kongdong sag in Dagang Oilfield were analyzed by triaxial compression experiments at different bedding angles and longitudinal and shear wave velocity tests. Dynamic and static stiffness coefficient, elastic modulus and acoustic wave velocity change under different directions of pressure and pressure relief. The results indicate that the P-wave velocity, fast shear wave velocity, slow shear wave velocity, dynamic and static Young’s modulus exhibit an increase as the confining pressure rises, and the parameters are greater during the unloading process than during loading process. At identical confining pressures, the dynamic Young’s modulus measured by cores with parallel bedding plane is greater than that measured by cores with vertical bedding plane. The dynamic and static elastic mechanical parameters of different bedding angles can be transformed under varying pressures, and the dynamic elastic mechanical parameters measured under varying levels of confining pressure can be transformed into static elastic mechanical parameters under equivalent confining pressures, which offer fundamental parameters for examining rock mechanics properties and serving as a reference for developing fracturing construction plans for oil and gas reservoirs.

Seismic inversion uses observed data, such as well-logging and seismic data, to infer rock parameters. However, it still suffers from nonunique solutions. The nonuniqueness increases when extrapolating away from the well location. To mitigate this effect, we incorporate geologic information into a deep-learning (DL) framework in the form of generated probabilistic labels. We transform geologic information into reservoir heterogeneity (RH) weights and geologic pattern constraint (GPC) weights to generate probabilistic labels. The RH weights are used to capture the variability in accuracy during the spatial extrapolation of well data. The RH weights are used to balance the constraint weights between well and seismic data in the DL model. The GPC weights are used to characterize the changes in geologic patterns from well locations to nonwell locations. Based on variations in local prestack seismic waveforms, the DL model learns extrapolation patterns of well data with similar geologic patterns. By combining the rock parameters derived from well logs with these two types of weights, we can generate a series of probability labels. Two types of geologic information and well-logging data are deeply integrated into a supervised 2D residual block UNet framework. In this way, we develop a novel DL-based prestack multitrace seismic inversion method. We validate our method on a 3D synthetic model and a 3D field data set. The results indicate that our method exhibits great potential for characterizing the spatial variation in subsurface rocks and outperforms traditional DL methods.

ABSTRACT Coal spontaneous combustion in goaf seriously affects the safety of mine production, and air leakage is one of the prerequisites for coal spontaneous combustion. Taking the ultra-long working face with a length of 410 m as an example, due to the insufficient compaction degree of the goaf, the high development of large-scale cracks, and the large air flow pressure difference between the intake and return air, the air leakage law in the goaf is not clear, and the risk of spontaneous combustion of broken residual coal increases. Based on the physical and mechanical parameters of coal rock, this paper studies the plastic failure and fracture development in the goaf under various stress disturbances in ultra-long working faces. The laws of gas migration and air leakage in goaf of ultra-long working face was studied by means of field test and numerical simulation. Based on the theory of coal-oxygen composite in goaf, the dangerous areas of coal spontaneous combustion in goaf with different mining sequence evolution of ultra-long working face were determined. Based on the distribution of air leakage flow field and coal spontaneous combustion danger zone in goaf, the comprehensive fire prevention and extinguishing technology of nitrogen injection inerting, plugging and leakage reduction was applied in field demonstration, and the application effect was verified. The research results show that the plastic failure range of overlying strata in goaf presents “saddle shape.” The permeability and porosity increase gradually from the middle to the surrounding direction, showing “O-ring” distribution. The main air leakage channels are concentrated at the intake air tunnel corner of the goaf and 160–200 m of the working face. The air leakage sinks are located at a distance of 20–80 m along the dip direction of the working face and at the return corner of the working face, respectively. The average air leakage is 268 m3/min and 153 m3/min, and the maximum width of the coal spontaneous combustion danger zone in the goaf during the dynamic advancement of the ultra-long working face is 107 m. Through comprehensive fire prevention and extinguishing techniques such as nitrogen injection for inerting and filling with high-molecular-weight gel for sealing and leakage reduction, the prevention and control of coal spontaneous combustion in ultra-long working faces at different mining sequences under corresponding engineering backgrounds are effectively ensured.

Background. The paper concerns the results of reservoir properties determination of carbon rocks of the Hnidyntsivske oil and gas condensate deposit of the Glynsko-Solokhiv gas condensate field with the purpose of looking into comprehensive analysis of their physical features. Methods. A brief petrographic description of limestones was performed. The bulk density of dry rock samples (matrix density of the rock) is determined by weighing and measuring their geometric dimensions. Hydrostatic weighing method was applied to the rock samples saturated with kerosene. The open porosity coefficient was determined by the gas volumetric method and the method of hydrostatic weighing according to the standard methodology. Capillarometric studies were performed by centrifugation of rock samples. Results. Such reservoir features of rock samples as open porosity coefficient and effective porosity coefficient, residual oil saturation factor and permeability coefficient were researched. The limits of variation and mean values of the reservoir properties of the studied rocks are given. The capillarometric studies by the method of centrifugation helped to understand the structure of the void space of rocks. Conclusions. The correlation analysis was applied to establish a number of correlations between the reservoir parameters of the studied rocks – density, open porosity coefficient, effective porosity coefficient and residual water saturation factor, as well as between the porosity coefficients measured in atmospheric and reservoir conditions. These correlations can be used for the interpretation of well logging data and modeling of reservoir parameters of consolidated reservoir rocks.

Rockburst prediction based on multi-featured drilling parameters and extreme tree algorithm for full-section excavated tunnel faces

Purpose. Justification of the methodology of rock research for crack resistance during longitudinal shear for the developed test device. Method. Method of laboratory investigation of fracture toughness of rocks under tension; methods of laboratory investigation of fracture toughness of rocks under transverse and longitudinal shear; analytical method for calculating shear stresses under torsional moment; analytical method for calculating the fracture toughness of rocks under longitudinal shear. Results. To predict roof collapse, the parameters of crack propagation in the rock mass above the mined-out area, the formation of rock falls, and gas-dynamic phenomena, it is necessary to take into account the processes of rock failure and fracturing of the rock mass. Laboratory investigation of the fracture resistance of rocks is a crucial task for forecasting roof collapse, rock falls, and gas-dynamic events. Therefore, the aim of this study is to justify the testing methodology for determining the fracture resistance of rocks under longitudinal shear using a specially designed device. A device has been developed and implemented for testing the fracture resistance of rock samples under longitudinal shear. To study the rock failure process in laboratory conditions, considering each failure mode, auxiliary testing tools were developed, and a methodology was substantiated for determining the fracture toughness parameters of rocks under longitudinal shear. A validated analytical method was proposed for calculating the fracture toughness parameters of rocks under longitudinal shear. Scientific novelty. For the first time, devices were developed to determine the fracture toughness of rocks taking into account the following types of fracture: tensile fracture toughness, transverse and longitudinal shear fracture toughness. For the first time, the method of testing rocks for crack resistance during longitudinal shear is substantiated. For the first time, the dependence of the calculation of the fracture toughness of test samples during longitudinal shear was established. Practical significance. The practical significance lies in determining the fracture toughness of rocks during tension, transverse and longitudinal shear.

Background. In the article the results of the physical modeling of oil flow through the reservoir rocks are described. In petrophysical laboratory sandstones of Rozumivske gas condensate field were studied. The aim of the research was to probe into petrophysical parameters of core samples of sandstones and the physical modeling of oil flow through them in reservoir conditions. Methods. Standard methods were performed to determine petrophysical parameters (density, porosity, the structure of void space, permeability) of sandstone samples in atmospheric conditions. The high-pressure installation was applied for physical modeling of the process of oil flow through the sandstone samples. Results. The reservoir (flow) properties of sandstone samples in atmospheric conditions and in the physical modeling of reservoir conditions are investigated. The values of the reservoir parameters of the studied rocks and their comparison are given. The structure of the void space of rocks and its analysis was evaluated. The results of studies of permeability of rocks for oil in different pressure-temperature conditions are presented. Conclusions. Via correlation analysis a number of correlations between the permeability of samples and the temperature and pressure in the reservoir conditions were established. These correlations can be used in the interpretation of geophysical studies of wells and modeling of reservoirs parameters of rocks. Then, the results of this research are going to be at the basis for studying the effect of vibro-wave and chemical methods on the filtration properties of such reservoirs in order to intensify hydrocarbon production.

Assessing the risk associated with drilling and wellbore stability studies requires the shear sonic log. These logs apart from distinguishing formation fluid from lithology are needed to obtain geo-mechanical rock parameters required for the safe design of rock fracturing. Although sonic logs are of great importance, they are usually not obtained due to the limiting cost of acquisition. Neural networks have been used to generate these logs to save cost, but these networks are prone to overfitting. The dropout rate has been proposed to tackle this problem, however selecting the optimum dropout probability rate can be challenging manually or expensive computation wise. This research therefore investigated concrete dropout, a dynamic technique for adapting the dropout rate of a neural network to the data. The concrete dropout technique was applied to an artificial neural network (ANN) and a convolutional neural network (CNN) model to predict the shear sonic log with Monte Carlo simulation. Comparison was also made with the deterministic ANN and CNN models which had no dropout layers added and a Bayesian-optimized multilayer perceptron (MLP) model. These models were trained and validated with four (4) wells from the Volve field, using features with the highest correlation. The Concrete dropout ANN was found to outperform both the deterministic versions and the MLP model with R2, RMSE, MSE and MAE scores of 0.9548, 3.6415, 2.4433 and 0.0179 respectively. The neural networks built in this study showed an enhanced predictive performance with concrete dropout addition over the networks with no dropout added, showing that the technique was able to adapt the dropout rate to fit the nature of data and improve performance, which finds great application in real time deployment. The findings of this study also proposed a cost-effective way of sampling and averaging multiple outputs from a single neural network model, leading to enhanced predictive performance as the addition of concrete dropout allowed the network output distributions rather than point predictions.

With the further development of China’s coal resources, mining operations are constantly transferred to the deep soft rock. As such, the mine roadway is under the action of high geostress, the surrounding rock body engineering properties are poor, the overall strength is low, the traditional support method struggles to meet the needs of safe production, and the surrounding rock control has become a major technical challenge. This paper relies on the actual project, analyzes the destabilization mechanism of the roadway, analyzes the deformation of the peripheral rock of the deep roadway, determines the physical and mechanical parameters of the peripheral rock through indoor tests, establishes numerical analysis model, proposes to adopt the joint support scheme of anchor rods + anchor cables + a 36U-type steel metal bracket + a laying net + a laying mat + filling behind the wall, and monitors the displacement of peripheral rock of the roadway on a regular basis by using the numerical display convergence meter, and then obtains the displacement of the peripheral rock of the roadway after excavation as well as under the influence of the quarrying movement. Under the influence of the roadway perimeter rock displacement, we evaluate the reasonableness of the support program, as well as the safe and effective control of the roadway perimeter rock, to achieve the ideal roadway perimeter rock support and control effect.

Изложен методологический подход к формированию горнотехнических систем глубоких карьеров, основанный на учете переходных процессов. Параметры и показатели подсистем горнотехнической системы и их элементы имеют большое количество взаимосвязей и претерпевают изменения в течение срока существования карьера. Их формирование рассматривается как совокупность периодов стабильного функционирования и переходных процессов. Описана терминологическая парадигма структуры, элементов и параметров горнотехнической системы карьера в приложении к карьерному транспорту. Приведена концепция адаптации технологической и технической подсистем при переходных процессах как механизм обеспечения оптимального уровня функционирования горнотехнической системы. Проиллюстрирован механизм обеспечения их динамического равновесия. Показаны элементы оптимизации параметров транспортной системы карьера как одного из наиболее затратных процессов при добыче полезных ископаемых открытым способом, основанные на применении комплексного компьютерного моделирования: геометрического, процессно-имитационного и экономико-математического. Описаны ключевые особенности учета устойчивости бортов карьера при обосновании параметров горнотехнической системы. Приведен подход к оптимизации параметров взрывной подготовки горной массы к выемке, основанный на оперативном уточнении физико-механических свойств пород и данных о горном массиве. The authors describe the methodological approach to formation of geotechnical systems of deep open pit mines with regard to transient processes. Parameters and figures of subsystems of a geotechnical system, and their elements have a great number of interconnections and undergo changes within the space of life of an open pit. Their formation is considered as a set of stable functioning periods and transient processes. The terminological paradigm of structure, components and parameters of the geotechnical system of an open pit mine is described in the context of the open pit mine transport. The concept of adaptation of the technology and equipment subsystems during transient processes is presented as a mechanism of optimal functioning of the geotechnical system. The provision of their dynamic equilibrium is illustrated. Optimization of transportation as the most expensive process in open pit mining is based on integration of computer modeling techniques: geometrical, process simulation and economic mathematical. The key features of pitwall stability estimates in substantiation of the geotechnical system parameters are discussed. The approach to optimization of rock mass preparation by blasting on the basis of real-time adjustment of physical and mechanical parameters of rocks and rock mass data is described.

Enhancing geothermal petrography with convolutional neural networks

Carbon capture and storage (CCS) is a novel technology that aims to reduce the presence of carbon dioxide from the atmosphere. This technology involves capturing CO2 from industrial sources or directly from the air, treating, transporting, and storing it in long-term safe rock formations. Basaltic rock comprises reactive minerals and glassy phases, which trap CO2 permanently through the mineralization mechanism. However, this method is complex mainly due to the rapid interaction between solid and liquid phases. The mineralization occurs at the interface between the reactive fluid and the basaltic rock surface, converting the dissolved CO2 into solid carbonate mineral that precipitates in the pores and fractures of the rock matrix. The reaction rate of a basaltic rock depends significantly on the CO2 wettability and rock-fluid interfacial interactions. However, there is limited information about the influence of the reactive surface on the reaction rate of minerals present in basalt formations. This work investigates the influence of kinetics parameters such as pH, temperature, and reactive surface area in the reaction rate of basaltic rocks. Basaltic rock dissolution and precipitation is assessed using the geochemical software PHREEQC. The proposed numerical model solves the reactive transport problem and provides feedback on the influence of the kinetics reaction parameters. The dynamics of the reactive surface during the reaction of basalt rocks is evaluated. The numerical results show the potential of basaltic rock for CO2 mineral storage as solid carbonates and identify the main factors that limit the mineralization process. Finally, this work provides a deeper understanding of CO2 mineralization that can provide valuable findings to guide Brazilian CCS projects.

This study presents a comparative analysis of vertical wells wellbore closure behaviour considering constitutive models with and without the incorporation of primary creep in salt rocks. In the context of drilling wells in the pre-salt region, one aspect that can jeopardise the operation is the phenomenon of creep, as time-dependent deformations accumulate and can lead to irreversible drilling column entrapment due to wellbore wall closure. Because of the complexity of drilling in salt formations, vertical trajectories are usually adopted in this region. During the design stage, well closure simulations are necessary to predict undesirable scenarios and thus assist in the appropriate selection of drilling fluids and the planning of reaming operations. Therefore, it is crucial to employ constitutive models capable of adequately representing the behaviour of salt rocks in these simulations. The constitutive model traditionally adopted for Brazilian rocks is the so-called Double-Mechanism of deformation. This model describes only the secondary creep stage, which is dominant over longer periods of time. This study focuses on comparing the differences between the results of well closure simulations with the Double-Mechanism and with the EDMT model (Enhanced Double-Mechanism using a Transient Function), which incorporates primary creep into the Double-Mechanism of deformation, thus being able to better represent short-term deformations. To achieve this objective, a case study is employed with the modeling of a synthetic well, using data consistent with real pre-salt wells. Elastic and viscoelastic parameters of saline rocks are obtained from the literature. The numerical simulation is performed using the finite element method. The well closure profiles of a well section obtained over time are compared. In the comparative analysis, the importance of primary creep in the well wall closure is further discussed by comparing critical time windows for restricting the passage of drilling equipment.

Introduction. Shaliness is an important lithological and petrophysical characteristic of reservoirs and seals in section of oil-and-gas boreholes as well as near-surface rocks (grounds) as the basis of buildings and engineering structures. Granulometric shaliness, determined by the presence of pelitic particles, and mineral shaliness, which characterizes the content of clay minerals, are distinguished in terrigenous rocks. In the sections of oil-and-gas fields, granulometric shaliness is one of the criteria for identifying reservoirs and affects their reservoir properties. The physical properties of reservoirs, which are studied by borehole logging, depend on the content and type of clay minerals. Information about clay minerals is taken into account when drilling and stimulation of hydrocarbon production. Shaly grounds apply to the group of cohesive ones, which in construction most often serve as the foundations of structures. At that these grounds are classified as difficult engineering-geological conditions for construction, since clay minerals specifically affect their strength, stability, etc. In oil-and-gas and engineering-geological boreholes the empirical equations relating gamma-ray logging readings and granulometric shaliness are most often used for quantitative estimation. Herewith, it is traditionally thought that the clay minerals make up the bulk of the pelitic particles. The paper is concerned with increasing the informativity of the borehole logging while investigating the shaliness of terrigenous oil-and-gas reservoirs and near-surface rocks based on a combination of gamma-ray logging, gamma-gamma density logging and neutron-neutron logging (GR+DL+NL). The investigation methodology included: borehole geophysical measurements by tools created at the Institute of Geophysics of the National Academy of Sciences of Ukraine independently and in collaboration with partner organizations; interpretation and analysis of logging data; justification and development of approaches to increase the informativity of the GR+DL+NL combination; estimation of the effectiveness of author's developments using independent criterions. As a result of the investigation, on the basis of the abovementioned logging combination, the set of determined parameters is increased as compared with the traditional practice; number of new methods is developed for determining the parameters of shaliness, among them the content of clay minerals, their density and hydrogen index. The use of these parameters, in turn, improves the accuracy of porosity determination and other reservoir properties from logging data. Method for estimating the type of clay mineral according to the GR+DL+NL data is proposed. The method is an available alternative to geochemical core studies and to more expensive and difficult logging methods. The novelty of the developments is confirmed by patents, and their effectiveness is confirmed by the results of borehole tests and comparison with independent determinations of parameters (laboratory core examinations, control logging data). Practical significance. The proposed approaches are an important component of technologies for investigating oil-and-gas reservoirs and near-surface rocks, which are being developed at the Institute of Geophysics of the National Academy of Sciences of Ukraine.