Biological methods are currently the most commonly used methods for removing hazardous substances from land. This research work focuses on the remediation of oil-contaminated land. The biodegradation of aliphatic hydrocarbons and PAHs as a result of inoculation with biopreparations B1 and B2 was investigated. Biopreparation B1 was developed on the basis of autochthonous bacteria, consisting of strains Dietzia sp. IN118, Gordonia sp. IN101, Mycolicibacterium frederiksbergense IN53, Rhodococcus erythropolis IN119, Rhodococcus globerulus IN113 and Raoultella sp. IN109, whereas biopreparation B2 was enriched with fungi, such as Aspergillus sydowii, Aspergillus versicolor, Candida sp., Cladosporium halotolerans, Penicillium chrysogenum. As a result of biodegradation tests conducted under ex situ conditions for soil inoculated with biopreparation B1, the concentrations of TPH and PAH were reduced by 31.85% and 27.41%, respectively. Soil inoculation with biopreparation B2 turned out to be more effective, as a result of which the concentration of TPH was reduced by 41.67% and PAH by 34.73%. Another issue was the phytoremediation of the pre-treated G6-3B2 soil with the use of Zea mays. The tests were carried out in three systems (system 1—soil G6-3B2 + Zea mays; system 2—soil G6-3B2 + biopreparation B2 + Zea mays; system 3—soil G6-3B2 + biopreparation B2 with γ-PGA + Zea mays) for 6 months. The highest degree of TPH and PAH reduction was obtained in system 3, amounting to 65.35% and 60.80%, respectively. The lowest phytoremediation efficiency was recorded in the non-inoculated system 1, where the concentration of TPH was reduced by 22.80% and PAH by 18.48%. Toxicological tests carried out using PhytotoxkitTM, OstracodtoxkitTM and Microtox® Solid Phase tests confirmed the effectiveness of remediation procedures and showed a correlation between the concentration of petroleum hydrocarbons in the soil and its toxicity. The results obtained during the research indicate the great potential of bioremediation practices with the use of microbial biopreparations and Zea mays in the treatment of soils contaminated with petroleum hydrocarbons.
The study evaluates the geothermal energy potential of two depleted oil and gas reservoirs representing two different lithostratigraphic formations—the carbonate formation of the Visean age from the basement of the Carpathian Flysch and the Rotliegend sandstone formation from the Eastern part of the Foresudetic Monocline, Poland. Advanced modeling techniques were employed to analyze the studied formations’ heat, storage, and transport properties. The obtained results were then used to calculate the heat in place (HIP) and evaluate the recoverable heat (Hrec) for both water and CO2 as working fluids, considering a geothermal system lifetime of 50 years. The petrophysical parameters and Hrec were subsequently utilized in the generalized c-means (GFCM) clustering analysis, which helped to identify the plays with the greatest geothermal potential within the studied formations. The central block emerged as the most promising area for the studied carbonate formation. It exhibited significant potential for heat production, with Hrec values of approximately ~4036 and 932 MW when H2O and CO2 were used as working fluids, respectively. The central block has three wells that can be easily adapted for geothermal production. The area, however, may require permeability enhancement techniques to increase reservoir permeability. Two prospective zones were determined for the analyzed Rotliegend sandstone formation: one in the NW region and the other in the SE region. In the NW region, the estimated Hrec was 233,855 MW and 44,018 MW, while in the SE region, it was 257,457 MW and 48,231 MW, using H2O and CO2 as working fluids, respectively. Both areas have high porosity and permeability, providing good storage and transport properties for the working fluid, and abundant wells that can be configured for multiple injection-production systems. When comparing the efficiency of geothermal systems, the water-driven system in the Visean carbonate formation turned out to be over four times more efficient than the CO2-driven one. Furthermore, in the case of the Rotliegend sandstone formation, it was possible to access over five times more heat using water-driven system.
Ensuring proper and effective cementing of casing pipe columns in boreholes requires maintaining appropriate technological parameters for the developed slurry recipes. It is also necessary to use technology which guarantees effective displacement of the drilling mud for cement slurry injection into the annular space of the borehole. The most important factors that ensure high efficiency of drilling mud displacement by the cement slurry are, among others, the rheological properties of the liquids involved in the process of cementing the casing columns (drilling mud, cement slurry, buffer liquid). The introduced version of the European cement standard, PN-EN 197-1, includes new types of very economical multi-component cements CEM V/A and CEM V/B, which contain 20–40% Portland clinker with a relatively high content of hydraulic and pozzolanic constituents. They occur in the form of granulated blast furnace slag, natural as well as industrial pozzolans and silica fly ash from the combustion of hard coal. The article presents the results of laboratory tests on the technological parameters of both fresh and hardened cement slurries prepared on the basis of CEM V multi-component cement varieties A and B. These slurries meet the standard technological parameters to a demanding extent, which makes it possible to apply them to cementing columns of casing pipes in deep hole drilling. Their detailed properties can be modified by introducing other mineral additives and chemical admixtures to the cement slurry recipes.
Glycerine (glycerol) is a polyol consisting of three carbon atoms bonded to hydroxyl groups. It is a by-product of the transesterification of triglycerides, such as animal fats, vegetable oils, or used cooking oils during the biodiesel production process. Crude glycerine is subject to purification processes resulting in distilled glycerine containing at least 99.5% glycerol. Currently, produced high-quality distilled glycerine is used in the food, pharmaceutical, and cosmetic industries. Recently, technologies for converting glycerol to other chemicals through catalytic processes have been intensively developed, e.g., production of bio-based 1,2-propanediol. In the near future, glycerol will certainly become a promising renewable raw material in many modern biorefineries for the synthesis of biofuels, chemicals, and bioenergy production. This paper presents the possibility of using ion exchange resins to remove impurities with trace amounts of sulphur and nitrogen compounds from crude and distilled glycerine, produced during the biodiesel production process from used cooking oils. It was determined that using ion exchange resins at the preliminary purification stage (before distillation) was ineffective. Using cationite resins to purify distilled glycerine produced from waste materials enables the removal of impurities in the form of sulphur and nitrogen compounds.
The aim of the research presented in this article was to analyse the processes of source-rock decomposition, including kinetic parameters of pyrolysis, in relation to the type of the organic matter and its maturity. The examined source rocks were Menilite shales from several units within the Flysch Carpathians (Poland). The samples were analysed with use of thermal methods, including Rock-Eval and thermogravimetry coupled with an FTIR detector. Kinetic parameters were determined with use of the model-free integral isoconversion method Kissinger–Akahira–Sunose. The observed gas evolution from the source rocks indicates two stages of organic matter decomposition for some samples. The main stage of pyrolysis takes place in the temperature range from 300 to 500 °C, while the secondary—cracking—takes place in the temperature range from 500 to 650 °C. Using FTIR, we detected vibrations derived from N-H groups, which provide information on the presence of nitrogen in the organic matter, and indicate a low maturity level. C=C stretching vibrations of aromatic hydrocarbons prove a higher maturity of organic matter. The Menilite source rocks have different activation energies, which are related to different organic and mineral compositions. The maturity of organic matter does not have a decisive influence on the kinetic parameters. A high share of carbonates in the rock increases the value of the apparent activation energy. The high share of bituminite within maceral components reduces the value of activation energy.
Ensuring effective sealing of casing columns in boreholes requires the use of the appropriate technology of cement slurry injection into the annular space and the use of a properly designed cement slurry recipe. Very often, when selecting the technological parameters of the cement slurry, special attention is paid to the technological parameters of the fresh cement slurry, but little attention is paid to the mechanical parameters of the cement sheath that is being formed (the cement slurry after setting). In order to improve the parameters of the hardened cement slurry in the annular space, the cement slurry of a new generation with increased durability (so-called geopolymers) is used. Slurries based on geopolymers are obtained by modifying slurries based on common-use cements with mineral additives with pozzolanic or hydraulic properties. Most often, these additives are fly ashes from the combustion of hard coal or ground granulated blast furnace slags. The article presents the results of testing the mechanical parameters of hardened cement slurries prepared on the basis of CEM V multi-component cement. It was found that the increase in the amount of silica fly ash in the slurry causes a delay in the strength growth rate; such slurries have lower values of early strength. The water–cement coefficient has the strongest influence on the mechanical parameters. The test results are also statistically developed, thanks to which it is possible to select the appropriate mathematical model, and this enables the prediction of mechanical parameters for slurries as a function of their hardening time. Such a mathematical solution can save some labor-intensive research, which, however, cannot be omitted in the final stage of slurry design.
The paper addresses the problem of geomechanical effects in the vicinity of production/injection wells and their impacts on the processes of enhanced oil recovery by CO2 injection and CO2 sequestration in a partially depleted oil reservoir. In particular, it focuses on natural fracture systems and their dynamics caused by variations in the rock geomechanical state due to reservoir pressure changes during production/injection processes. The comprehensive approach to the problem requires the combined modeling of both geomechanical and flow phenomena associated with effective coupling simulations of their evolution. The paper applies such an approach to a real, partially depleted oil reservoir in Poland. An effective method of coupled geomechanical and dynamic simulations was used together with the natural boundary and initial conditions for both simulation types. In addition, typical operating conditions were applied in analyzing the processes of enhanced oil recovery by CO2 injection and CO2 sequestration. The detailed results of relevant modeling and simulations are presented and discussed focusing on various scale consequences, including the reservoir, well, and completion ones. Both general conclusions as well as the ones specific to the analyzed geological structure are drawn; they confirm the significant dependence of well performance on geomechanical effects and point out several key factors for this dependence. The conclusions specific to the analyzed structure concern fracture reactivation in tensile/hybrid failure mode caused by pressure build-up during CO2 injection and the importance of the fracture-induced aperture changes resulting from the normal stress, while the shear stress is found to be negligible.
The purpose of this review paper is to show the possibilities of carbonate reservoir characterization using well logging and laboratory measurements. Attention was focused on standard and new methods of well logging acquisition and interpretation including laboratory experiments to show a part of the history of carbonate rock investigations as hydrocarbon or water reservoirs. Brief information on the geology, mineralogy and petrography of carbonate rocks was delivered. Reservoir properties, i.e., porosity (including fracturing), permeability, and saturation, were defined to emphasize the specific features of carbonates, such as fractures, and vugs. Examples of methodologies were selected from the commonly used laboratory techniques (thin sections examination, mercury and helium porosimetry, X-ray diffraction—XRD) combined with the standard well logs (bulk density—RHOB, neutron porosity—NPHI, sonic slowness—DT, and deep resistivity—Rd) to show the methods that have been used since the very beginning of the scientific and engineering studies of carbonates. Novelty in well logging, i.e., resistivity and acoustic imaging, nuclear magnetic resonance–NMR, dipole shear sonic imaging–DSI, and a spectral neutron-gamma log-geochemical device–GLT combined with modern laboratory investigations (NMR laboratory experiments, scanning electron microscopy SEM), showed how continuous information on mineral composition, porosity and saturation could be obtained and juxtaposed with very detailed laboratory data. Computed X-ray tomography (CT) enabling the 2D and 3D analyses of pores and fractures was presented as a quantitative methodology, effective in pore space characterization, revealing rock filtration abilities. Deep learning and artificial intelligence were used for joining various types of data. It was shown that thanks to new computational technologies original data from very small samples (micro scale), extensively describing the flow ability of the reservoir, could be extended to mezzo scale (core samples) and macro scale (well log images). Selected examples from the published papers illustrated the review. References cited in the text, together with the issues included in them, were the rich source of the practical knowledge processed These were checked by the authors and could be used in other projects.
The review presents methods that are used frequently for multi-analytical study of fossil resins. The preliminary characterization relies on physical methods such as microhardness, density and fluorescence in UV light measurements. The spectroscopic methods: infrared spectroscopy, Raman spectroscopy, fluorescence spectroscopy are also presented in the paper. Besides that, the review also contains examples of the application of chromatographic methods: gas chromatography, thin layer chromatography, high-performance liquid chromatography, two-dimensional gas chromatography coupled to time-of-flight mass spectrometry as well as sample preparation methods for chromatographic studies such as pyrolysis. Additionally, thermal methods such as thermogravimetric analysis and differential scanning calorimetry also are covered by the review. Beside the examples of application, a detailed description with development history and perspective for further improvement are presented for each method. Moreover, fit-for-purpose assessment of each method is illustrated based on many examples from literature. The paper also contains examples of the application of multivariate statistical analysis and chemometric methods for comparing multiple properties of different fossil resin specimens for differentiation and classification purposes.
Zinc oxide layers on soda-lime glass substrates were fabricated using the sol-gel method and the dip-coating technique. Zinc acetate dihydrate was applied as the precursor, while diethanolamine as the stabilizing agent. This study aimed to determine what effect has the duration of the sol aging process on the properties of fabricated ZnO films. Investigations were carried out with the sol that was aged during the period from 2 to 64 days. The sol was studied using the dynamic light scattering method to determine its distribution of molecule size. The properties of ZnO layers were studied using the following methods: scanning electron microscopy, atomic force microscopy, transmission and reflection spectroscopy in the UV-Vis range, and the goniometric method for determination of the water contact angle. Furthermore, photocatalytic properties of ZnO layers were studied by the observation and quantification of the methylene blue dye degradation in an aqueous solution under UV illumination. Our studies showed that ZnO layers have grain structure, and their physical-chemical properties depend on the duration of aging. The strongest photocatalytic activity was observed for layers produced from the sol that was aged over 30 days. These layers have also the greatest porosity (37.1%) and the largest water contact angle (68.53°). Our studies have also shown that there are two absorption bands in studied ZnO layers, and values of optical energy band gaps determined from positions of maxima in reflectance characteristics are equal to those determined using the Tauc method. Optical energy band gaps of the ZnO layer fabricated from the sol aged over 30 days are Eg I = 4.485 eV and Eg II = 3.300 eV for the first and second bands, respectively. This layer also showed the highest photocata-lytic activity, causing the pollution to degrade 79.5% after 120 min of UV irradiation. We believe that ZnO layers presented here, thanks to their attractive photocatalytic properties, may find application in environmental protection for the degradation of organic pollutants.
The beginning of 2022 was a time of major changes in the perception of energy availability and security in European countries. The aggression of Russia against Ukraine destabilizing the Eu-ropean energy economy, combined with the withdrawal from fossil fuels which has been going on for a dozen years, has strengthened activities to introduce new energy technologies based on renewable energy sources. One of the most promising and stable sources of renewable energy is geo-thermal energy, in particular enhanced geothermal systems (EGS) in hot dry rocks (HDR). These deposits occur at a great depth in almost every place on Earth, but due to their low permeability, they require hydraulic fracturing, which results in high investment costs. This technology has been developed for several decades. The current situation in Europe seems to confirm that its rapid development to a level that guarantees stable and profitable operation is crucial. This is of particular importance in the case of former member states of the economic zone of the Council for Mutual Economic Assistance, which until recently were heavily dependent on Russian energy. This review, based on the latest available data, covers potential HDR prospective areas in the countries of the southeastern Baltic basin, including Lithuania, Latvia, Estonia and Poland. It is specific to this region that the original heat flux density is lower as a result of the paleoclimatic effect associated with the youngest ice age; however, thermal conditions do not deviate too much compared to western Europe, especially Rhine Graben, and significantly exceed the conditions of Finland, where an EGS project is currently being operated. In Lithuania, the most prospective area is the ZNI intrusion (south of Klaipeda), characterized by a geothermal gradient of up to 40 °C/1000 m. In addition, the Precambrian batholith south of Liepāja (Latvia) and the Rapakivi granites in the north and center of Estonia are promising EGS sites. Poland has relatively the most explored EGS potential, in both volcanic, crystalline and sedimentary rocks, especially in the area of the Szczecin Trough, Gorzów Block, Moglino-Łódź Trough and Karkonosze Mountains. Unfortunately, local tectonic conditions, in particular the development of faults and natural fracture zones that affect the directions of fracture propagation during hydraulic fracturing, have not been sufficiently recognized, which is one of the main barriers to the expansion of EGS pilot projects in these countries. These issues present challenges for the researchers, especially in terms of petrophysical analyses of rocks in target zones and local stress conditions, which have a key impact on fracturing operations and profitability of the systems. Despite high investment costs on the one hand and a significant slowdown in the global economy in 2022 on the other, it remains hopeful that the authorities of individual countries will decide to accelerate research work, leading to the implementation of pilot projects of EGS installations , and that this technology will be further improved to ensure a stable clean energy supply. Citation: Moska, R.; Labus, K.; Kasza, P.; Moska, A. Geothermal Potential of Hot Dry Rock in SouthEast Baltic Basin Countries-A Review. Energies 2023, 16, 1662.
Abstract: The introduction of the hydrogen economy, despite its obvious technological problems, creates a need for a significant number of niche-focused solutions, such as small-sized (10-100 W) fuel cells able to run on hydrogen of lesser purity than what is considered a standard in the case of PEMFCs. One of the solutions can be derived from the fact that an increase in the operational temperature of a cell significantly decreases its susceptibility to catalyst poisoning. Electrolytes suitable for the so-called medium temperature operational range of 120-400 • C, hence developed, are neither commercialized nor standardized. Among them, phosphate silicate protonically conductive glasses were found not only to reveal interestingly high levels of operational parameters, but also, to exhibit superior chemical and electrochemical stability over their polymeric counterparts. On the other hand, their mechanical properties, including cracking fragility, still need elaboration. Initial studies of the composite phosphate silicate glasses with uranyl-based protonic conductors, presented here, proved their value both in terms of application in fuel cell systems, and in terms of understanding the mechanism governing the charge transport mechanism in these and similar systems. It was found that whereas systems containing 10-20 wt% of the crystalline additive suffer from significant instability, materials containing 45-80 wt% (with an optimum at 60%) should be examined more thoughtfully. Moreover, the uranyl hydrogen phosphate was found to surpass its arsenate counterpart as an interesting self-healing behavior of the phase structure of the derived composite was proved.
Modern internal combustion engines are designed to meet new emission standards and reduce fuel consumption. The wide application of direct fuel injection is associated with the problem of injector contamination. It leads to a deterioration of the engine’s environmental performance. The paper aims to evaluate the effect of applying gasoline–butanol blends and appropriate additives on the formation of injector deposits. The research involved testing the engine on a dynamometer, evaluating the injector tips visually at 1000× magnification, and registering the fuel spray using high-speed imaging techniques with a laser and halogen lighting source. The effect of engine operating with the reference fuel was to coke the injector tip with a linear pattern. It increased the linear injection time to keep the engine’s operating point constant over the 48 h test. The application of 20% (v/v) butanol reduced deposit formation. The best scavenging results were obtained by extending the engine operating time by the next 24 h and using a cleaning procedure. The procedure included a cleaning additive in addition to butanol. Among the cases analyzed, a combination of butanol and DCA (Deposit Control Additive) was the best method for injector patency restoration.
Global economic development and the associated increase in consumption increase the demand for plastics. The result of these changes is the increase in the share of this group of used plastics in the structure of household waste. An innovative way of managing plastic waste is to use it as a component of a high-energy material. According to the conceptual assumptions, some plastics introduced into the structure of an explosive (Ex) in appropriate amounts can improve the energy parameters of a high-energy material. Modification of the composition of the explosive causes a change in its explosive and operational parameters. It also becomes necessary to develop a method of introducing an additional component. Computer programs for thermodynamic calculations are a tool for modeling the predicted energy parameters of an explosive. The performed simulations and modeling allow for the selection of appropriate compositions for laboratory and “in situ” tests. This reduces the number of field tests performed. This enables the more effective design of new explosive compositions. The use of waste plastics as a corrector of explosive properties may also be pro-environmental in nature through the use of a detonation method of their disposal and will reduce the cost of manufacturing the product. The conducted analyses showed that for three ANFO-type explosives containing 2% polyethylene—PE 2.0, 1% polypropylene—PP 1.0 and 1% polyurethane—PU 1.0, obtained energy parameters similar to ANFO and qualitatively and quantitatively similar structure of post-detonation gases.
The extraction of hydrocarbons is associated with obtaining certain amounts of water, which is heavily contaminated with a wide range of chemical compounds that negatively affect the environment. At present, practically the only method of managing extracted reservoir waters is their injection into absorbing horizons. Large changes in parameters (pH, Eh, temperature, etc.) occurring during the extraction and storage of water, as well as the contact of the injected water with reservoir water and rock, may result in the precipitation of secondary sediments. The complexity of the injected water/native water/deposit rock system and the wide range of possible interactions do not always allow for correct interpretation of the processes and their impact on near-well zone permeability. One of the factors which has a decisive influence on dissolution/precipitation is temperature change. Applying analytical data of water with low (W-1) and high (W-2) mineralization, calculations were carried out with the use of PRHEEQC software. Changes in solubility index values were determined at ambient temperature (20 °C) and reservoir temperature (94 °C). The obtained results indicate that with increasing temperature, SI changes for a given chemical compound may run in different directions and take different values, depending on the composition of the injected water. The calculations indicate the possibility of a change in the direction of the reaction from dissolution to precipitation, which may lead to clogging of the near-well zone. Simulations of the injected water’s contact with minerals present in the reservoir rock were also carried out. The obtained data indicate that these minerals, in the entire studied temperature range, dissolve in the injected water, but the solubility of anhydrite and dolomite decreases with increasing temperature. If the water is saturated with minerals at low temperature, after heating in the bed, sedimentation and blockage of rock pores may occur, which means there is a reduction in the efficiency of water injection.
Hand‐dug oil wells, located in natural crude oil seep sites, are remnants of historical exploitation activities. Hydrocarbon pollution is regarded as the threat to soil ecosystem. On the other hand, there is no common environmental policies regarding these soils. The hypothesis was that natural attenuation processes might occur in seep soils since a diversified and stable bacterial community structure should be a result of its long‐term (thousands of years) adaptation to hydrocarbon exposure and should be associated with eventual utilization of these compounds. To obtained this goal, we compared the structure, composition, and hydrocarbon‐degrading potential of bacterial communities inhabiting soils with different hydrocarbon contents (seep, hydrocarbon‐impacted, pristine soils), which were collected in two habitats (forest, meadow). 16S rRNA sequencing and isolation of hydrocarbon degraders were performed. The contaminant's presence shaped distinct and unique community structure and composition, and it enhanced physiologically and functionally adapted microorganisms. The most abundant community members were bacteria revealing a strong contribution in genetic potential toward aerobic hydrocarbon transformation (i.e., Mycobacterium/Mycolicibacterium and Pseudomonas ). The strong hydrocarbon degraders population suggests that natural biodegradation occurs in situ in seeps and mitigates the pollution impact on adjacent soils. Seep and hydrocarbon‐impacted soils are a great source for remedial bacterial populations. Twenty‐four genera of degraders were isolated; however, strains belonging to the Mycobacterium/Mycolicibacterium, Rhodococcus , and Pseudomonas taxa were common. Our results underline the need to include undervalued microbiological aspects in remediation projects' guidelines for chronically polluted environments. The knowledge regarding seep communities should help to evaluate more efficient remediation strategies for anthropogenic spills.
Every year, the number of exploited mine workings necessary to seal the exploited mines increases in the world. As a result of experiments, technologies are developed that allow slurry to be pumped to fill free rock spaces or to liquidate rock mass discontinuities. The slurry preparation technologies can be divided into: subsurface and surface preparation and injection. Due to the pressure that forces the sealing slurry to move, the following can be distinguished: pressure technologies and technologies of gravity injection. The effectiveness of the work is determined by the correct selection of the technique and technology of the treatment and the selection of the optimal cement slurry recipe. The type of sealing liquid is especially important during works related to filling the exploited mine workings in salt mines. Therefore, this article presents the criteria for the selection of slurry recipes and their technological parameters, used for sealing and strengthening the salt rock mass. For this purpose, laboratory tests are carried out on various formulas of sealing slurries, prepared on the basis of full saturated brine and CEM I 32.5R Portland cement, ground granulated blast furnace slag, fly ash, and silt. The proposed concept for the selection of sealing slurry formulas has been positively verified during the performed works on sealing and strengthening the salt rock mass.
The article explains the differences between synthetic fuels of first and second generation. The potential of e-fuels to reduce GHG emissions was indicated. The application requirements that synthetic fuels need to meet in order to be used for powering internal combustion engines have been described. The possibility of using synthetic fuels as "drop-in" fuels, in blends with conventional petroleum-derived fuels as well as by themselves was discussed. E-fuels developed and optimized to power compression ignition and spark ignition engines were characterized. The possibilities of synthetic fuels to reduce emissions of regulated and unregulated exhaust components and to improve the work and operational parameters of the engine were also analyzed using the research carried out so far as basis. At the end of the article, forecasts for synthetic fuels development and applications were presented in the form of a SWOT analysis.
Low-speed pre-ignition (LSPI) is a problem for many highly boosted engines and constitutes a major industry challenge. This paper provides an overview of the reasons that might lead to low-speed pre-ignition. These reasons have been systematized and divided into four groups related to the engine, fuel, lubricating engine oil, and engine operating conditions. In the case of the engine, particular attention was drawn, among others, to the type of fuel injection, the method of mixture formation, the compression ratio, and piston design as important factors affecting the occurrence of pre-ignition in the case of stochastic self-ignition. The paper analyzes the influence of the engine operation and the adjustment of its operating parameters on the frequency of occurrence of low-speed pre-ignition. The paper extensively discusses the relationship between the engine lubricating oil including the oil base groups and its additives and the occurrence of abnormal combustion. The impact of different types of detergents was considered in more detail. The paper also describes the effects of the fuel properties on low-speed pre-ignition. The most important fuel properties from the point of view of its confirmed influence on the formation of low-speed pre-ignition are the its chemical composition, deposit control additives and volatility. The conclusion emphasizes that the operating conditions in a modern downsized, turbocharged gasoline engine can induce a low-speed pre-ignition problem, which can lead to destructive super-knock events. It was indicated that low-speed pre-ignition tends to become more prominent in the operating regime that is most beneficial to attaining improved fuel economy. Therefore, the solution to this problem is considered to be a key factor in further development of downsizing and improving the engine efficiency. An innovative element of the article, which distinguishes it from other similar articles, is the proposed logical division and systematization of the hitherto identified factors influencing the LSPI phenomenon. This has been done by separating, comprehensively listing and ordering these factors
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