Cracking Of Oil Research Articles

Analysis of the stability of cracked soil slopes using a numerical model incorporating stochastic theory

Desiccation crack is a prevalent natural phenomenon that plays a significant role in the stability of soil slopes. In this study, a hydromechanical coupling model incorporating a layer of stochastic cracks is developed for analyzing cracked soil slopes. To properly consider the anisotropy and spatial variability of desiccation cracks, three crack indices are generated through cross-correlated random fields via Cholesky decomposition. The seepage and mechanical behavior of a cracked slope are analyzed by adjusting stochastic parameters and rainfall conditions. Applied to the Ningzhen Mountains area in China, the model investigates the stability of slopes under various annual meteorological conditions. The results indicate that neglecting the spatial variability of cracked layer properties can lead to inaccurate assessments of instability risks at the base and water accumulation at the top of slopes. During heavy rainfall, slopes with deeper (up to 5 m) and weaker cracked layers often show a roughly planar sliding morphology. Moreover, the uncertainties in crack depth have the most pronounced influence on the uncertainties of the slope stability, more than horizontal permeability or crack aperture. The average crack aperture’s influence on slope stability depends on the relationship between crack infiltration rate and rainfall intensity.

Reducing the environmental impact of aluminum production through the use of petroleum pitch

This study is aimed at developing a technology for obtaining petroleum pitch as a binder for anode mass used in the electrolytic production of aluminum from fuel oils of catalytic liquid-phase oxidative oil cracking. A review of published data on the existing methods for obtaining petroleum pitch and its properties is carried out in order to define research directions. A method for producing petroleum pitch by catalytic liquid-phase oxidative cracking of crude oil using heterogeneous metal complex catalysts is proposed. The process of petroleum pitch production is shown to undergo several stages, including homogenization of fuel oil and modifying additives; oxidative cracking of fuel oil during heating of homogenized fuel oil in a furnace; catalytic liquid-phase oxidative cracking of fuel oil with removal of distillates; rectification of light fractions; condensation of distillates; collection of light oil products; oxidation of bottom residues by air and steam; removal of oxidation distillates and petroleum pitch; and pitch pelletizing. According to the conducted comparison of the as-obtained petroleum pitch with the B-1 coal tar pitch produced by the Altai Koks JSC, the proposed material meets the technological requirements of the Krasnoyarsk Aluminum Plant of the RUSAL company. In terms of sulfur content, the proposed petroleum pitch is superior to coal tar pitch. The experiments conducted at an aluminum plant showed the petroleum pitch to contain no harmful polyaromatic hydrocarbons, in particular, carcinogenic benz(a)pyrene. Therefore, replacement of coal tar pitch with petroleum pitch could provide technological and environmental advantages for primary aluminum producers, as well as for enterprises producing various carbon materials.

Effects of geometry of soil specimens on the formation of desiccation cracks

Desiccation cracks in soils are important in engineering structures that need hydraulic integrity such as earth dams, and containment facilities. At the element test level, such cracks are a hindrance when the volume change of the soil specimen needs to be measured during the test. One such test is the volumetric shrinkage test where the volume of the soil specimen needs to be continuously determined together with its mass change as the soil specimen dries. The soil specimen may deform non-uniformly. Previously hazardous and cumbersome methods using mercury or wax are needed to determine the volume of soil specimens that deform non-uniformly, but the advent of 3D scanning and photogrammetry enables the volume of non-uniform soil specimens to be measured quite accurately. However, such techniques cannot accurately determine the volume of the deformed soil specimen once cracks start appearing in the soil specimen. Volumetric shrinkage tests are commonly conducted for cylindrical soil specimens. This paper investigates the geometry (shapes and dimensions) of soil specimens other than cylindrical on the formation of desiccation cracks. Bentonite is used as the test soil as it experiences large volume change on drying. The test results provide guidance for the geometry of a soil specimen to be used in the volumetric shrinkage test.

Recycling of polyethylene waste in the process of catalytic cracking of vacuum gas oil

Recycling of polyethylene waste in the process of catalytic cracking of vacuum gas oil

Influence of ultrasound on thermal cracking of vacuum gas oil in a mixture with waste vegetable oils and tire crumb

Influence of ultrasound on thermal cracking of vacuum gas oil in a mixture with waste vegetable oils and tire crumb

Oxidative desulfurization of VGO using carbon nanostructures created by NTP-pyrolysis of fuel oil

Desulfurization of heavy oil fractions is complicated due to the high content of stable polycyclic systems including thiophene ring. Therefore, there is a need to develop new efficient and cost-effective desulfurization methods. The catalytic activity of carbon structures obtained by plasma-chemical pyrolysis of hydrocarbon feedstock (fuel oil, non-hydrorefined vacuum gas oil and catalytic cracking residue) was investigated in this work. The catalytic activity of carbon structures was investigated in relation to the process of oxidative desulfurization of light vacuum gas oil. The oxidation process was carried out at 60°C using ultrasonic dispersion for 1 minute. The oxidation products were extracted with furfural. As a result of oxidation followed by extraction, the sulfur content in gas oil decreased from 0.64 to 0.24% wt.

Effect of temperature, hydrogen donor, and zeolites on light cycle oil cracking: thermodynamic, experimental, and DFT analyses

Experimental, thermodynamic, and DFT analyses determine optimal conditions for maximizing BTX yields from LCO and provide mechanistic insights.

Evaporation and desiccation cracking of soils: Experiment evidence and insight on the freeze-thaw cycle dependence

The cracking of clayey soils in seasonally frozen regions is affected by cyclic drying-wetting and freezing-thawing. Understanding the mechanism governing soil cracking behavior is crucial for the construction and long-term operation of infrastructures and earthworks. In this study, a series of laboratory tests were conducted on clayey soils, including freezing-thawing tests and evaporation tests. The evaporation rate and surface cracks evolution were monitored. The cracking mechanism of soils were analyzed. Results show that both the initially unsaturated and oversaturated soils exhibit an increase in evaporation rate with increasing freeze-thaw (FT) cycles in the early stage. Under the same FT and drying conditions, initially unsaturated soils show a higher evaporation rate in the early stage than oversaturated soils, followed by a lower rate after entering the residual stage. In addition, cyclic FT accelerates the propagation of the number of crack segments, surface crack ratio, and total crack length, but weakens the propagation of average crack width. Moreover, it was found that for initially unsaturated soils, desiccation-induced matrix suction plays a leading role in producing wide, rough, and curved desiccation cracking patterns. While for initially oversaturated soils, freezing-induced ice pressure/cryogenic suction dominates, resulting in short, fine, and straight frost cracking patterns.

Experimental Study of the Dynamic Characteristics of PVA-Amended Expansive Soils

Expansive soils are distributed across a wide area in China, and land transport and surface construction will inevitably involve these soils. To mitigate the deficiencies of single-method expansive soil modification, it is highly important to adopt the use of polyvinyl alcohol (PVA) to improve expansive soils and enhance the strength and toughness of modified soils. In addition, solidification technology can be utilized for the resource utilization of expansive soils. In this study, triaxial testing is employed to evaluate the mechanical properties of solidified soil. When the confining pressure is the same and with increasing PVA content, soil particles and PVA combine to form a cemented substance, which fills the internal pores of the soil samples, enhances the cohesion between soil particles, and improves the bearing capacity of the soil. The stress–strain curve for the modified soil first increases and then decreases. The shear strength peaks at a PVA content of 3%. Based on the improved soil with a 3% PVA content, GDS dynamic triaxial tests were carried out to investigate the effects of different confining pressures and frequencies on the dynamic stress–strain curves, dynamic modulus of elasticity, and variation rule for the damping ratio of the improved soil. The results show that the dynamic stress–strain curve for the improved soil increases with increasing confining pressure and frequency and that the dynamic stress–strain backbone curves exhibit significant nonlinearities at different frequencies and circumferential pressures. The dynamic elastic modulus increases with increasing confining pressure and frequency and decreases gradually with increasing dynamic strain. The initial dynamic modulus of elasticity increases with increasing envelope pressure and frequency but is less affected by frequency, and the damping ratio decreases with increasing confining pressure and frequency. Soil treatment can improve the pore distribution, inhibit the extension of soil cracks, and enhance soil compactness.

Maximizing light olefin production via one-pot catalytic cracking of crude waste plastic pyrolysis oil

Energy-efficient processes for converting polyolefinic waste plastics into light olefins are critical for mitigating environmental pollution and reducing carbon emissions. In this study, an alternative recycling scheme, the catalytic cracking of crude waste plastic pyrolysis oil (WPPO) over microspherical P-modified steam-treated ZSM-5 (ms-P-HZSM5-S), was demonstrated and compared to a state-of-the-art commercial scheme, the thermal cracking of a hydrotreated naphtha range of WPPO. The C2–C4 olefins yield achieved by the catalytic WPPO cracking (56.6 wt%) exceeded those achieved by the thermal WPPO cracking (36.1 wt%), thermal naphtha cracking (23.1 wt%), and catalytic naphtha cracking (29.7 wt%), which indicated the superiority of WPPO over naphtha as a feedstock. However, during a deactivation test over ms-P-HZSM5-S, coke accumulation resulted in a rapid decline in the yields of ethylene (from 17.2 to 14.6 wt%), propylene (from 25.8 to 23.6 wt%), and benzene, toluene, and xylenes (from 16.1 to 13.4 wt%) after a reaction time of 810 s (temperature = 680 °C, weight hourly space velocity = 16 h−1). Nevertheless, the catalytic performance was fully restored through regeneration in air at 730 °C, which confirmed the viability of continuous operation involving successive reaction–regeneration cycles. These findings can be leveraged to devise a new approach, the catalytic cracking of WPPO integrated with a continuous regeneration (e.g., circulating fluidized bed reactor) system, which could offer several advantages over the commercial strategy, including the posttreatment-free utilization of the entire WPPO range, higher light olefins yields, continuous coke removal, reduced energy consumption, and non-necessity of H2.

Effects of layer thickness on desiccation cracking behaviour of a vegetated soil

The objective of this study is to explore how different layer thicknesses affect the desiccation cracking behaviour of vegetated soil. During the experiment, an electronic balance was employed to quantify water evaporation, while a digital camera was utilized to capture the initiation and progression of soil surface cracking. Results indicate that in the early drying process, the rate of evapotranspiration in vegetated soil correlates positively with leaf biomass. For soil samples with the same layer thickness, the constant rate stage duration is consistently shorter in vegetated soil samples than in their bare soil counterparts. As the layer thickness increases, both vegetated and bare soil samples crack at higher water content. However, vegetated soil samples crack at lower water content than their bare soil counterparts. Vegetation significantly reduces the soil surface crack ratio and improves the soil crack resistance. The crack reduction ratio is positively correlated with both root weight and length density. In thicker vegetated soil layers, the final surface crack length noticeably declines.

Comparison of various sustainable amendments on soil cracking in semi-arid regions

Soil desiccation is an important process that happens mainly in semi-arid regions especially in Central Asia. Soil desiccation leads to higher loss of moisture at shallower depths and also deeper penetration of water, which ultimately reduces water availability and hence impacts the growth of plants for the application of agriculture and green infrastructures. Therefore, minimizing soil desiccation will help maintain higher water availability for plants for agricultural productivity and green infrastructure in Central Asian Region. In literature, various amendments such as natural fibers, cementation, lime, vegetation and biochar have been used to suppress cracking of soil. There is rarely any study that analyses and compares mechanism of crack suppression among the above-mentioned methods. The objective of this study is to explore various sustainable methods of minimizing soil desiccation and compare their mechanisms. Further, the aim is to analyse the feasibility of these methods by revealing their advantages and disadvantages. In order to achieve this objective, 1-D columns were prepared with control soil and amended soil (with fibers, vegetation and biochar). The review also provides insights into their mechanism of suppression of soil cracking by proposing a new factor (i.e., normalized CIF). Based on the proposed factor, the efficiency of biochar and fiber amendments are higher than that of vegetation. Vegetation may or may not have positive impact on cracking of soil depending on their shoot length. Among various amendments, wood biochar (10% content) and coir fiber (at 0.75 % content) seems to have highest efficiency in reducing cracking in soil. Overall, the study aims to develop preliminary guidelines suppressing soil desiccation in semi-arid regions such as Central Asia.

Impact of earthquake’s epicenter distance to failure of the embankment – A seismic prediction

Cracks in clayey soil cause a reduction in the seismic loading capacity which can lead to structural failures. Seismic acceleration is the primary cause of crack propagation and damage to the earth's structure. This study investigated the impact of the earthquake's epicenter distance on the embankment model with a pre-existing crack in the embankment's core. The research adopted the numerical modeling method of soil categorized as a no-tensile material to explain displacement in selected points of the model using the extended finite element method (XFEM). Artificial Neural Networks (ANNs) were used to predict displacement obtained by XFEM. It was observed that the failure pattern and the maximum displacement time of the model change with the associated distance of the earthquake's epicenter. The key study objective is to understand the model's failure mode and introduce a new classification in earthquake damage prediction.

Cracking of heavy-inferior oils with different alkane-aromatic ratios to aromatics over MFI zeolites：Structure-activity relationship derived by machine learning

This paper investigated the performance of catalysts with different morphology in cracking of heavy-inferior oil (HIO) to aromatics with different alkane-aromatic ratios (AAR), which include high and low-temperature coal tar (HMCT, SMCT), liquid products of coal-oil co-refining (LCOCR and HCOCR) and petroleum (YLP). The experimental results indicated that Na+ and OH− have a competitive effect on the catalyst morphology, and that low alkalinity in the synthesis system favors the synthesis of 2D zeolites. The highest selectivity of aromatics in the products of HMCT, SMCT, HCOCR and YLP after catalysis by fast pyrolysis-gas chromatography/mass spectrometry can reach 92.8 %, 44.5 %, 51.7 % and 42.0 %, which are 8.9 %, 36.3 %, 38.2 % and 39.3 % higher than those in non-catalytic pyrolysis under the same conditions, respectively. The catalyst with a high amount of strong acid facilitates the conversion of HIO, and it is noteworthy that the presence of aromatics in HIO will contribute to the aromatization in the reaction, which is of great significance in promoting the deep processing of HIO. The structure-activity relationship between catalysts and products was investigated by machine learning, and the importance of features on the selectivity of BTEX decreases in the order of ASS > AST > HFʺ >Smicro > Dpore size.

Fracture morphology of desiccation cracks in clayey soil

Desiccation cracks compromise soil integrity and weaken its strength, causing a range of detrimental consequences across various domains. Elucidating the cracking mechanism can aid in managing crack propagation and mitigating the associated risks. This study monitored and compared the evolution of crack patterns on the soil surface and fracture morphologies on the soil cross-section during the drying process using a tested soil sample. Multiple fracture morphological features are discerned on the soil cross-section, encompassing initiation points and plumose structures. Soil fracture morphologies are categorized into three cases based on the initiation point's location, referred to as “Top-initiated structure”, “Bottom-initiated structure”, and “Truncated structure”. Experimental results demonstrate that plumose structures result from the division of the crack front under mixed-mode loading. Cracking under mixed-mode I + II loading leads to cross-section tilting, resulting in curved surface cracks. Conversely, cracking under mixed-mode I + III loading causes cross-section twisting, generating hackle lines and step structures. Furthermore, the crack front radiates from the initiation point, creating orthogonal hackle lines. The geometric relationship confirms that the soil fracture morphology is a good indicator of the cracking process, both in laboratory tests and field observations.

Origin of gas condensate reservoir in Fuman Oilfield, Tarim Basin, NW China

To understand the reservoir property and hydrocarbon accumulation conditions of the Middle and Upper Ordovician intraplatform shoal between ultra-deep main strike-slip faults in Fuman Oilfield of the Tarim Basin, China, the main strike-slip faults in and around well FD1 in the basin were analyzed in terms of sedimentary facies, sequence stratigraphy, intraplatform shoal reservoir property, and oil and gas origins, based on drilling data. The Yingshan Formation intraplatform shoal between the main strike-slip faults is superimposed with low-order faults to form a new type of hydrocarbon play. Firstly, hydrocarbons generated from the Lower Cambrian Yuertusi Formation source rocks vertically migrated into the second member of Yingshan Formation through the main strike-slip faults, and then migrated laterally until they were accumulated. A small amount of oil from Well FD1 came from the Yuertusi Formation source rocks in the mature stage, and a large amount of gas originated from oil cracking in the ultra-deep reservoirs. Therefore, the secondary gas condensate reservoir in Well FD1 is characterized by high gas to oil ratio, dry gas (dryness coefficient being 0.970) and hybrid origin. This new type of hydrocarbon play characterized by intraplatform shoal and low-order fault suggests a prospect of continuous hydrocarbon-bearing area in Fuman Oilfield, which will expand the ultrap-deep oil and gas exploration in the oilfield.

Investigation into Xanthan Gum Biopolymer on Mitigating Cracking and Erosion Behavior of Soil

Investigation into Xanthan Gum Biopolymer on Mitigating Cracking and Erosion Behavior of Soil

Infiltration performance evaluation of a 15-year-old concrete grid paver parking area (Italy)

Abstract The management of urban stormwater needs a wide array of environmentally friendly solutions to safeguard water resources and improve the quality of the urban environment. In that, permeable pavements, a type of sustainable drainage system, are designed to reduce the volume and peak flow of stormwater on-site, improve infiltrating water quality, and combat the urban heat island phenomena. In this study, we tested the infiltration capacity of 15-year-old concrete grid pavers (CGPs) using single ring infiltrometer tests. We investigated how various factors, including location within the parking space, affect infiltration rates. Despite no maintenance and 15 years of operation, the infiltration capacity of the CGPs still exceeds the minimum infiltration capacity of 1.62 mm/min as required in many European regions. This may be due to the presence of soil cracks and the development of plant roots and insect/microorganism activities within the pavement voids. Indeed, this ‘living soil system’ continuously develops and counteracts the formation of clogging, interacting with the compaction process. Our study demonstrates that incorporating CGPs is effective in addressing emerging challenges associated with urban hydrology. Due to effectiveness and limited maintenance requirements, CGPs could be successfully included in long term climate adaptation measures.

Effect of Accelerated Physical Weathering of Coarse Soils and Wetting and drying Cycle on Some Soil Physical Properties

soil samples were collected in May the 5th, 2021 from wadi Al-Muhammadi) Al-Mohammadi valley(in Al-Anbar governorate in western Iraq. The trail consisted of four treatments. In the first treatment, the sample Is passed through a 2000 μm metal sieve, while in the fourth treatment the sample is crushed or milled to size 70μm sieve. In the second treatment, the mixture ratio of soil was 25:75 (natural: Crushed). In the third treatment, the mixture ration of soil was 50:50 (natural: crushed). This paper determined in the soil coefficients for penetration, the density sustainability, soil porosity, as well as scanning soil aggregates using an electronic microscope samples passed through cycle of wetting and drying the results showed that the decrease was evident in soil penetration resistance in recent cycles in conjunction with the decrease in soil bulk density significant because of mechanical pulverization and cycles of wetting and drying along with an increase in soil porosity. the proportion of soil cracks resulting from shrinkage and swelling has been calculated and It was found that it increases with the percentage of clay in the soil. The electron microscope images show the soil was influenced by the mechanical pulverization during the first three cycles, as for the wetting and drying cycles, their effect appeared in the last cycles, the partial transformation of mica to mineral 2:1 was observed with the progression of wetting and drying cycles.

Does the fertilisation strategy affect the long-term legacy phosphorus dynamic?

Phosphorus (P) imbalances in agricultural systems are a global problem because they have environmental and economic impacts, like eutrophication when there is a soil P surplus and low crop productivity in P deficient soils. Fertilisers are used to increase soil available P, but some fractions become less available P forms and reduce P use efficiency (PUE). Legacy P includes labile and moderately labile P fractions that could replenish soil available P and become available for crops under long-term P fertilisation and affects PUE. Our aim was to evaluate the long-term legacy P dynamic and PUE with different P fertilisation strategies and rates in soils of Entre Ríos, Argentina. Long-term experiments in two contrasting soil types (Mollisol and Vertisol), were used to evaluate a combination of three initial (0, 100, and 200 kg P ha−1) and four annual P fertilisation rates (0, 12, 24, and 36 kg P ha−1 year−1). Soil samples were collected annually at 0–5 cm, 5–10 cm, and 10–20 cm soil depth. Bray1-P concentration was used as an index of soil available P. Grain P concentration and crops grain yield were measured. The effects of the initial P fertilisation on Bray1-P were observed for a longer time in the Mollisol than the Vertisol, which may be related to a lower P adsorption capacity of the Mollisol. Annual P fertilisation increased Bray1-P earlier in deep layers in the Vertisol, associated with the preferential flow of P fertiliser through soil cracks in the latter. After 10 years, Bray1-P stratification was higher in the Vertisol than in the Mollisol. In the treatment without initial P fertilisation (i.e., 0 kg P ha−1), the annual fertilisation rate to maintain Bray 1-P level was similar on both soils (on average 24 kg P ha−1). Our results showed that the annual P fertilisation strategy to feed crops’ needs produces higher PUE compared with the use of residual legacy P after an initial and unique high P fertilisation rate. This information is relevant to design highly efficient P fertilisation strategies according to soil characteristics, thereby advancing the pursuit of sustainability in agricultural systems.