Difficult Geological Conditions Research Articles

Effect of surface plastic deformation of drill pipes material on their technological properties

Relevance. The need to study the effect of surface plastic deformation of drill pipes on their technological properties, which will significantly reduce the irrational material and energy costs of drilling wells, as well as optimize the technical and economic indicators of drilling operations. Aim. To increase the productivity of geological exploration by optimizing the operational characteristics of drill pipes. Objects. Drilling well, drilling shell, drill string, shot blasting of pipes, surface plastic deformation. Methods. Specialized test benches have been developed and manufactured for conducting experimental studies; processing of experimental research data was carried out by the graphoanalytic method. Results. The paper introduces the results of the study of the effect of surface plastic deformation produced by means of shot-impact treatment of the surface of the drill pipe material on their technological properties. The conducted studies shown a significant effect of surface plastic deformation of drill pipes on their technological properties and operational characteristics. In particular, it was found that microcracks and other microdefects can lead to a decrease in the strength and fatigue resistance of the pipe, as well as to a deterioration in its corrosion resistance. Conclusions. The optimal degree of surface coating of LBTN-54 and SBT-42 drill pipes, which guarantees a significant improvement in their technological properties, is close to 80%. With an optimal degree of surface plastic deformation of the material of LBTN-54 drill pipes the stiffness of their cross-section increases by 1.8 times; torsional stiffness increases by 1.3 times; damping capacity increases by 33%, and the amplitude of free vibrations decreases by an average of 1.9 times; power costs for turning them around their curved axis increase by 15%. At the optimal degree of surface plastic deformation of the SBT-42 drill pipe material the stiffness of their cross-section increases by 1.43 times; torsional stiffness increases by 1.4 times; damping capacity increases by 25%, and the amplitude of free vibrations decreases by an average of 1.75 times; power consumption for turning around its curved axis decreases by 7%. Surface plastic deformation of the LBTN-54 drill pipe material contributes to the expansion of the areas of their operation in the well in the mode of direct precession, which ensures the improvement of technical and economic indicators of drilling in difficult geological conditions.

Long-Term Interaction of Submerged Tunnels with Rheological Rock Masses & Time-Dependent Permeability

Submerged tunnels may pass through rock types and may encounter a variety of difficult geological conditions. One of these challenging conditions is confronting with highly stressed weak rock masses. The challenge pertaining to design of these tunnels is intensified when water seepage occurs into tunnel. In this condition, the rheological behavior of the rock mass causes the pressure acting on the lining to enhance over time, and consequently, the permeability coefficient of the rock mass in any point is changed over time. This paper investigates this problem, the tunnel construction process is all simulated in this study. Furthermore, based on the rock mass volumetric strain, a time-dependent variable permeability is assigned to the rock mass around the tunnel. A parametric study is conducted to evaluate the effect of rock mass rheological parameters, the internal water pressure, and the ratio of the rock mass and lining permeability on the submerged tunnel behavior. The results show that the internal water pressure extremely influences the tunnel response. Moreover, the permeability variation of the rock mass should be necessary, but unfortunately this is not feasible in most computer codes for three-dimensional numerical modeling.

Well operation by plunger rod pumps in difficult conditions

Purpose. Research and optimization of the processes of operation of wells equipped with plunger rod pumps in conditions with increased complexity, such as high oil viscosity, high pressure, aggressive geological and physical conditions and significant fluctuations in flow rate, in order to increase the efficiency and reliability of the plunger rod pump (UPSH) installation, increase well productivity and reduce operating costs. Methodology. The authors used the following scientific methods: the method of analysis and synthesis – for a review and systematization of existing scientific publications and experiments on the operation of wells with UPR in conditions of increased complexity; the method of observation and data analysis – for an analysis of the operation of UPR in various conditions, including the study of the effectiveness of their work in difficult geological conditions; experimental methods – for conducting field experiments to evaluate the work of UPSH in conditions of increased complexity. Findings. The use of inhibitors, tubing (tubing and compressor tubes) with protective coating, rod centralizers and special pumps is proposed to combat wiping and deposits in deep pumping equipment. Low-cost options are recommended for use in small and medium-sized wells up to 1,500 m deep, providing an efficiency of 50‒60 % with a viscosity of up to 200 MPaˑs and a sand content of up to 10 %. Originality. The theory of the causes of the failure of the GNR and the downtime of the mechanized fund of production wells equipped with UPSH has been further developed. The influence of complicated conditions on the operational characteristics of plunger rod pumps has been established. The use of OPN in production wells at the Uzen field is justified, taking into account technical and economic factors in comparison with other methods of operation. Practical value. The development and implementation of methods that increase the inter-repair period of wells at the Uzen field make it possible to reduce the cost of repair and preventive maintenance, increase the efficiency of operation and reliability of the mining complex, especially at a late stage of field development. As a result of the pilot tests conducted, the average duration of the inter-repair period of the mechanized fund in 2021 increased by 14 days compared to 2018.

Well sealing technologies with the possibility of controlling the rheological properties of cement composite by external influence

The problem of long-term tightness of oil and gas wells is extremely acute for the oil and gas industry, both in terms of efficient and trouble-free operation of wells, and the most serious environmental problems associated with leaks and gushers of oil and gas at operating and abandoned wells. The article presents an up-to-date review of experimental studies, promising traditional and alternative technologies for completing and abandoning wells in difficult thermobaric operating conditions or associated with temperature and other influences to activate and control the rheological properties of cement compositions. When cementing wells in difficult geological conditions, the oil and gas industry faces the problems of creating plugs capable of withstanding extremely high pressures, temperatures and loads. In this case it makes sense to consider plugging technologies based on self-healing and regeneration effects, thermite compositions, eutectic metals, thermosetting resins and polymers. Based on the analysis of modern cementing materials and well sealants, the author proposes a set of key characteristics that a cement slurry should have in order to be able to control its physical and mechanical properties and its ability to re-liquefy under the influence of temperature, pressure or other external factors.

Inhibited Solutions for Wells in Complicated Geological Conditions in the Areas of South-Western Turkmenistan

Shortcomings in methods for assessing the condition and composition of clayey rocks and shales lead to lower drilling cycle rates and profits and do not allow for proper quality of well construction in difficult geological conditions. The purpose of this study was to develop an optimal method of selecting the drilling mud composition when drilling wells in clay rock deposits. The following methods were used in the study: method of X-ray diffraction analysis of clay minerals; comparative analysis; method of mathematical statistics; side-tracking method. It was found that at equal wetting ability of clays, the fixing properties of the ALCAR-1 system are 3.5-4 times higher than those of the lime-potash system. Thus, with the same degree of stability, the water yields as well as drilling speeds may be higher with ALCAR than with the lime-potash system. The study of clayey rocks from the section of well No. 5 in the Bugdaily area showed that they have colloidality high enough for deep-seated clays, as they have a high content of montmorillonites. Drilling mud characterisation study found that mud samples No. 1, 2, and 3 had a strong inhibitory effect. The most effective sample was No. 3, which was able to ensure a stable state of clayey rocks for 90-100 days. The study of interaction of drilling fluid system ALCAR-3 with clayey rocks, carried out in the fields of south-western Turkmenistan, found that the inhibitory effect of the No. 3 sample can be further enhanced by the addition of 3% potassium chloride. The findings of this study can be used for successful drilling operations of deep wells in the areas of fields with complicated conditions associated with wellbore instability in the preparation of inhibited drilling fluids.

Substantiation and selection of parameters for supporting mine workings at deep levels

Purpose.The research aims to conduct a comprehensive study on substantiation and selection of optimal parameters for supporting mine workings at deep levels by analyzing the stress-strain state (SSS) of the rock mass, modeling geomechanical processes and developing effective strengthening technologies in difficult geological conditions. Methods. The research includes modeling of the stress-strain state of the rock mass using ANSYS, Phase2 and Prorock software packages. To assess and predict the stress-strain state of the mass in the area of stope blocks, a series of numerical experiments have been conducted to analyze the near-contour rock mass stability. The physical-mechanical characteristics of ores and host rocks are used as input data for modeling. Findings. The mass SSS analysis has confirmed that increasing the number of cable bolts up to four provides mine wor-king stability, but is accompanied by intensive fracture formation beyond the contour, as well as convergence up to 14 cm, which requires the use of reinforcing mesh and reinforcing frame in two layers. The mining system elements have been found to provide the necessary safety factor for end ore drawing (ks ≥ 3.0) and slicing mining with hardening backfill (ks ≥ 5.0). Originality. The parameters for supporting mine workings have been substantiated, which ensures safe mining of deep levels. It has been revealed that when backfilling, the height of the caving zone is 125 m and the fracture zone is 60 m. For mining systems with caving, these figures reach 280 and 470 m, respectively. Practical implications. The technology has been developed for supporting capital mine workings with the use of reinforced combined support and roof bolts. The results obtained contribute to the improvement of reliability and efficiency of mining operations by providing accurate prediction of rock behavior under conditions of changing stresses and reduction of their strength characteristics.

IMPROVING THE EFFICIENCY OF DRILLING INCLINED AND HORIZONTAL WELLS

One of the most pressing issues in the field of oil and gas production is improving the efficiency of drilling wells. This paper examines the most important aspects of improving the methods of drilling inclined and horizontal wells and increasing their efficiency. Inclined and horizontal wells are of particular importance in difficult geological conditions, as well as in the effective development of oil and gas resources. These methods increase not only the volume of oil and gas production, but also the possibility of reducing environmental impact, reducing economic costs and using production time more efficiently. The paper examines modern technologies and methods used to improve the efficiency of drilling inclined and horizontal wells, including new materials and drilling equipment, as well as digital technologies and automation systems. In addition, the geological difficulties encountered during well drilling and their solutions are analyzed, as well as engineering methods aimed at optimizing the drilling process.

Efficiency of a new type of plasticizer for cementing solutions

Abstract As of today, oil and gas wells are 6,000 m deep or more. In view of this, increased requirements are imposed on the grouting materials used in wells. Grouting fluids must have rheological properties with low values of dynamic shear stress (τ) and plastic viscosity (η). Reducing the values of τ and η will provide a turbulent flow regime of cementing fluids, which is favourable in terms of complete replacement of the washing fluid with the cementing fluid. In the course of the research, it was found that the Melamine-Formaldehyde Anionic-active Resin superplasticiser is a reagent that has a multifunctional effect on cementing dispersions. This makes it possible to use it in difficult geological and technical conditions for well cementing.

ნორიო - 72 ჭაბურღილის გეოლოგიური ჭრილის სტრატიგრაფიული დანაწილების შესახებ

Norio-72 well was drilled by CanArgo Georgia ltd in 2002-2006, within of North board of the eastern end of the Adjara-Trialeti folded zone. Purpose of drilling was specification of geological structure of the territory, penetration and potential evaluation of known, oil-bearing vulcanic-sedimentary formation of region near Tbilisi. Drilling was conducted in a very difficult geological conditions and ended with heavy collapse at 4900m. It is still a matter of discussion whether the well had penetrated Middle Eocene productive layers. Solving this problem has a significant meaning for specification the depth structure of the above mentioned territory and for oil-gas exploration issues. According to the complex analysis of geological (biostratigraphic, lithological-mineralogical), gephisical (exploration and production) and drilling data and on the basis of our study of basically to the microscopic research of about 1000 samples (drilled parts of rock) we can conclude that the well had not penetrated the vulcanogens of Middle Eocene. It penetrated Upper (Middle and Lower Sarmat), Middle (Konkian, Karagan, Chokrak, Tarkhan), Lower Miocene (Kotsakhuri, Sakharaulo) and Oligocene (4230-4900m interval) thick sandy shale formation in a consistent manner. Last 90m of the geological section of the well is formed by Maykop formations not the tuffs, mainly non-carbonaceous, almost mute shale rocks partially, sandstones and siltstones, as it turns out, most part of the hole is located in the thick, intensively deformed zone of tectonic (thrust) fault, which cannot be the object of oil and gas productive accumulation.

Investigating Factors Influencing Crash Severity on Mountainous Two-Lane Roads: Machine Learning Versus Statistical Models

Due to poor road design, challenging terrain, and difficult geological conditions, traffic accidents on mountainous two-lane roads are more frequent and severe. This study aims to address the lack of understanding of key factors affecting accident severity with the goal of improving mountainous traffic safety, thereby contributing to sustainable transportation systems. The focus of this study is to compare the interpretability of model performances with three statistical models (Ordered Logit, Partial Proportional Odds Model, and Multinomial Logit) and six machine learning models (Decision Tree, Random Forest, Gradient Boosting, Extra Trees, AdaBoost, and XGBoost) on two-lane mountain roads in Yunnan Province, China. Additionally, we assessed the ability of these models to uncover underlying causal relationships, particularly how accident causes affect severity. Using the SHapley Additive exPlanations (SHAP) method, we interpreted the influence of risk factors in the machine learning models. Our findings indicate that machine learning models, especially XGBoost, outperform statistical models in predicting accident severity. The results highlight that accident patterns are the most significant determinants of severity, followed by road-related factors and the type of colliding vehicles. Environmental factors like weather, however, have minimal impact. Notably, vehicle falling, head-on collisions, and longitudinal slope sections are linked to more severe accidents, while minor accidents are more frequent on horizontal curve sections and areas that combine curves and slopes. These insights can help traffic management agencies develop targeted measures to reduce accident rates and enhance road safety, which is critical for promoting sustainable transportation in mountainous regions.

DEVELOPMENT OF PROJECT DOCUMENTATION FOR WELL CONSTRUCTION WITH THE USE OF MPD TECHNOLOGY

In traditional drilling technology, in order to prevent gas and oil-water blowouts, the pressure in the well should exceed the reservoir pressure by 5–10 % in static conditions, depending on the depth. However, in case of catastrophic sinking, drilling of highly permeable formations, narrow drilling windows in zones of abnormally high pressures such a safety method, on the contrary, often makes it impossible to drill the well. Today there are special systems to control the pressure in the well during deepening and circulation stops for drilling in difficult geological conditions. Their work is based on high-precision control of pressure in the annulus and its regulation at the sealed wellhead by means of an automatic choke in combination with a Coriolis flow meter. In static conditions, the required pressure is maintained either by an additional pump or by a nitrogen injector.Development of well construction projects requires reference to industry specific normative documents regulating the methodology of work, equipment selection and defining the minimum list of other technical and technological solutions necessary for quality and safe drilling operations. However, despite the fact that the technology of drilling with controlled pressure in different variations has been used in Russia for twenty years, there are still no regulatory documents summarizing the entire domestic experience of its application and regulating the procedure of drilling operations with controlled pressure. Their absence leads to certain technical risks and difficulties in passing departmental expert reviews of project documentation.This article analyses the rules and recommendations for well construction using managed pressure drilling technology contained in national industry regulatory documents, highlights the problems arising in the development of the technical part of the design and estimate documentation for the construction of similar wells, and gives recommendations on the composition of a regulatory document that could summarize national and foreign experience of managed pressure drilling.

Hydrodynamic Model of the Area of the Żelazny Most Mining Waste Storage Facility to Reconstruct the Migration of Saline Groundwater

This paper presents the construction of a numerical three-dimensional model of the area of the Żelazny Most Mining Waste Storage Facility (MWSF). In the study area, the difficult geological conditions associated with glaciotectonics are accompanied by a complex hydrotechnical system of sediment deposition and sedimentary water drainage. In order to effectively reflect the water flow paths, a detailed schematization was carried out, using 700,000 boreholes and more than 300 hydrogeological cross-sections. In addition, numerous drainage sections, streams, and ditches were included to reliably assess the amount of saline water entering the underlying aquifers. This research was supported by magnetic resonance sounding (MRS) studies of the reservoir’s sediments. The MWSF is currently being expanded, so the work primarily focuses on illustrating changes in the hydrodynamic field resulting from the inclusion of the new southern section. Models of similar facilities have been implemented before, but in the current one, the combination of meticulous analysis of the hydro-structural system, the water balance, a significant amount of data, the size of the facility, and the use of an unstructured discretization grid in the calculations is undoubtedly innovative and will be an important contribution to the development of analogous solutions around the world.

Drilling of Directional Wells in the Fields of Western Turkmenistan

The investigation of drilling directional wells in the fields of western Turkmenistan is relevant at the present time, as it can contribute to the optimisation of hydrocarbon production processes in the region, increasing the efficiency and sustainability of production. The purpose of this study is to analyse and evaluate aspects of drilling directional wells in the fields of western Turkmenistan to determine their potential for increasing hydrocarbon production and reducing operating costs. Among the methods used, the analytical method, the classification method, the functional method, the statistical method, and the synthesis method etc., should be noted. The study is an extensive examination of the experience of drilling directional wells and cluster drilling in western Turkmenistan’s oil and gas fields, which considers modern technological advances. Within the framework of this study, potential directions for the development of technology for drilling directional wells were considered, and recommendations were formulated on the use of specialised equipment and high-quality materials for cluster drilling in the south-western part of Turkmenistan. The use of modern technical solutions that meet international standards has led to the successful completion of cluster drilling of directional wells at fields in this region. This study is a substantial starting point for the future development of the technology of cluster drilling of deep directional wells, especially considering high reservoir pressures, and it contributes to the technical renewal and organisational restructuring of the cluster drilling process based on scientific research. The study on drilling directional wells has practical value, enabling the optimisation of the production of oil and gas resources in difficult geological conditions and increasing the efficiency of production in this region.

Investigation of the Gubadag deposit clay minerals properties and development of drilling fluids based on them

The study of the properties of clay minerals and the creation of innovative drilling fluids based on them are extremely important aspects for improving the processes of extraction of natural resources, reducing operating costs, and increasing the energy efficiency of industrial operations. The purpose of this study was to explore the possibilities of developing a composition of drilling fluids based on the investigation of the properties of clay minerals for drilling and maintenance of wells in the conditions of the Gubadag deposit located in Turkmenistan. Statistical methods, experiments, and analysis were used in the course of the work. The results of the study showed that clay from the Gubadag deposit is characterised by low hydrophilicity and weakened structural stability, which is manifested in limited hydration energy and high filtration permeability. This leads to low viscosity, rheological, and structural-mechanical parameters of natural solutions. It follows from this that Gubadag clay is classified as a low-quality material. The prepared solutions from the above samples on different types of water have volumes in the range of 2-3 m³. However, after treating sea water with caustic soda, sample No. 2 generates more than 4 m³ of solution, significantly different from other samples. This highlights the need for additional research to optimise drilling fluid formulae, since it is important to determine the effect of clay materials on the properties of solutions and develop more adapted formulae that consider the specifics of the material and the conditions of its use in drilling wells. The practical significance of the results obtained lies in a significant improvement in the efficiency of drilling and maintenance of wells in regions with difficult geological conditions, offering new methods for preparing drilling fluids.

Peculiarities of using small-diameter bored piles for effective solving of geotechnical problems

Abstract. The peculiarities of the use of small-diameter drill piles in modern construction considered, with an emphasis on their advantages and areas of application in specific conditions. Two main types of piles distinguished: cast-in-place, which characterized by continuous reinforcement and filling with concrete or cement mortar, and composite, where the load transfers to reinforcing elements. Main advantages of small-diameter bored piles noted, including the possibility of performing work in confined spaces, reducing the level of noise and vibrations, a variety of drilling technologies, the possibility of application in geological conditions of varying complexity, etc. Particular attention paid to the areas of application of small-diameter bored piles, including the installation of new foundations, underpinning of existing structures, soil improvement and land-slide protection. The main groups of factors that can influence the choice of small-diameter bored piles as the main design decision for various fields of application considered, including: - physical factors (restricted access, remoteness of the area, distance of piles to existing structures); - subsoil factors (difficult geological conditions, soil liquefaction tendency); - environmental factors (sensitivity to vibration/noise, hazardous or contaminated soils); - necessity of adaptation to existing structures; - load/settlement requirements; - economic factors. Limitations for the use of small-diameter drill piles from the point of view of their efficiency described. An example of the effective practical use of small-diameter bored piles in the confined conditions of dense urban development in close proximity of metro tunnels with increased requirements regarding the level of vibrations and noise considered. The task of minimizing subsidence of the designed residential and office complex and the impact on surrounding buildings and structures solved. The compliance of the adopted design decisions confirmed by means of field tests, as well as using the results of settlements monitoring. Attention focused on the need for further improvement of design approaches and technological solutions to optimize the efficiency of small-diameter bored piles for solving geotechnical problems.

Cover Picture: Geomechanics and Tunnelling 3/2024

Abstract In Stockholm, Implenia builds of one of the world's deepest metro stations. This new metro station is an extension of the Blue Line to Södermalm. Beside the station single‐track tunnels for the subway, lift shafts, and a collateral service tunnel are constructed. Due to the difficult geological conditions and the bad quality rock, the AT – Pipe Umbrella System with squeeze connections were used to reinforce excavations and bolster safety during construction (photo: DSI Underground).

METHODOLOGY AND FEATURES OF RESEARCH OF FILTRATION PROPERTIES OF COMPACTED DEEP-SEATED ROCKS

As a result of the depletion of conventional hydrocarbon reserves, there is a need to explore deposits at great depths and under difficult geological conditions. This requires the improvement of technologies for studying rocks and fluids using computer modeling systems and laboratory equipment. Laboratory modeling of the processes occurring in rocks during drilling, development, stimulation or various chemical treatments plays a significant role in modern hydrocarbon production, as it reduces the number of errors at the design stage of field development or methods of impacting productive formations. There are a number of well-known manufacturers of laboratory equipment that model filtration processes in rocks, but any system has both advantages and disadvantages. To implement the tasks of studying filtration processes in rocks, technologies for the development of compacted and conventional reservoirs, stimulation methods and physical and chemical effects in hydrocarbon production, filtration equipment has been developed that allows for standard and special studies of rock core material. The first low-pressure unit allows for fast and accurate measurements of porosity and permeability at pressures up to 10 MPa and temperatures up to 120℃. In addition to filtration processes, the equipment allows for evaluation studies of the impact of various chemical solutions, drilling and other process fluids on natural and artificial cores in scientific and industrial research. For the study of rocks and fluids in reservoir conditions, a filtration system has been developed that allows for all of the above studies at pressures up to 100 MPa and temperatures up to 200℃. The peculiarity of the developed equipment is high accuracy of measurements, automation of monitoring processes, corrosion-resistant design of the main components and assemblies, which allows conducting research in any aggressive environment. Laboratory studies allow avoiding mistakes in the design of new areas development, reducing drilling accidents and selecting effective technologies for rock impact.

Assessing stability of mine workings driven in stratified rock mass

Purpose.The research purpose is to assess the stability of mine workings driven in a stratified rock mass by studying the influence of the stratified rock bedding angle on the rock mass stress-strain state (SSS). Methods. The research uses both experimental and numerical methods. Experimental studies are carried out using rock samples with different angles of rock layer occurrence, while numerical modeling is performed using the RS2 (Geotechnical Finite Element Analysis) software based on the generalized Hoek-Brown failure criterion. The studies are carried out on models covering the border area of the mine workings driven in the mass with the angles of rock occurrence from 0 to 75°. Findings. Experimental and numerical studies have shown that when the rock layer inclination angle changes, significant changes occur in the stress concentration zones around the mine workings. An increased rock layer inclination angle is accompanied by a change in stress distribution, which is important for assessing the stability of mine workings. A particularly strong influence is observed at the angles of rock occurrence 30° and above. Originality. The research novelty is in revealing the patterns in the stress distribution in the stratified rock masses depen-ding on the rock layer inclination angle. Research results provide new data on the rock interaction mechanisms in difficult geological conditions. Practical implications. The results obtained can be used in the planning and operation of mine workings in difficult geological conditions. By taking into account the changes in stress zones caused by the rock layer inclination angle, it is possible to improve the safety and efficiency of mining operations.

Integrated approach to prediction of dynamic phenomena in difficult geological conditions in coal mines using geophysical and satellite survey data

Integrated approach to prediction of dynamic phenomena in difficult geological conditions in coal mines using geophysical and satellite survey data

Detection of hazardous zones in development headings in difficult geological conditions

Detection of hazardous zones in development headings in difficult geological conditions