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With the increasing interest in unconventional resource plays, there have been important changes in the way how reservoirs and their attributes are assessed and characterized. Of particular relevance to the development of unconventional plays has been the focus on the assessment of organic porosity. A review of the available literature reveals contradictions with respect to where organic porosity develops (kerogen, bitumen, or pyrobitumen), when it develops with respect to hydrocarbon generation and cracking (within the oil window or beyond), its mode of formation (inherited or authigenic), the influence of organic carbon content, and the importance of organic porosity with respect to hydrocarbon storage and production. Many of these apparent contradictions appear to result from the nature of the data sets upon which the studies are based. Organic pore size generally limits the role that organic porosity plays in liquid-rich plays. From the available literature, it has become clear that there are number of issues that need to be clarified when addressing organic porosity. One such issue is terminology. There appears to be confusion in the usage of the terms kerogen, bitumen, and pyrobitumen. This confusion exists in the literature and reports prepared by various service providers for those engaged in the exploration and exploitation of unconventional resources. Another issue is the observed differences in the morphology of the organic pores (e.g., spongy, isolated bubbles, or fractures). Differences in pore morphology indicate multiple mechanisms for formation and/or growth of organic pores, suggesting more complexity to organic porosity development than often implied. For example, the spongy appearance of organic pores in some systems could reflect the amorphous character of some oil-prone kerogen, whereas the bubble pore character could be the result of degassing during the transition from the oil window into the gas window or an artifact of decompression and degassing as bitumen solidifies during core retrieval. Similarly, fractures could be a result of the conversion of oil to gas and the inability of the gas to escape or could be desiccation cracks, possibly formed after sample retrieval. Organic pores, if present in situ, increase space for hydrocarbon storage and increase surface area resulting in higher absorption capacity. However, the connectivity of these pores may be somewhat limited and may be dependent on the nature of the organic network, thus limiting their impact on permeability. A challenge when studying organic porosity is its observed variability within an individual reservoir. Very different spatial distribution of pores can occur between adjacent organic particles (e.g., macerals, solid bitumen) as well as within individual “macerals”. It has been suggested that this could be, in part, a result of organic–inorganic interactions although alternative interpretations have also been proposed. Further complicating the scientific understanding of organic porosity is the possibility that the act of studying the samples containing these pores may result in alteration of the rocks and the pores themselves. Therefore, observed organic pores may not be reflective of native conditions. The lack of a clear understanding of organic porosity development in unconventional mudstone reservoirs is by no means a surprise. Porosity and its development in conventional reservoirs have been studied since Sorby began the examination of sandstone thin sections in 1850 and is still under examination, while organic porosity has been studied for less than a decade. The focus of this study is to provide a review of porosity associated with the organic fraction, which may, in some shale-reservoirs, play a key role in hydrocarbon storage, migration, and production. [ABSTRACT FROM AUTHOR]

Currently, the manual method using hand-held infrared temperature measurement instruments for measuring temperatures on the external surfaces of ethylene cracking furnace tubes is highly subjective and is affected by a number of prominent issues, such as the high temperature working environments, which leads to low efficiency and poor measurement accuracy. Hence, an automatic temperature measurement system based on infrared light is designed and realized. In the system, a dual-phase drive synchronization method is proposed to rotate the thermodetector during horizontal movements, thus realizing automatic batch temperature measurements of the furnace tubes. Moreover, a temperature processing algorithm is developed to automatically identify furnace wall and tube surface temperatures, filter out abnormal temperatures and select only high-quality temperature measurements prior to calculating the final result. Real temperature measurement experiments demonstrated that the dual-phase drive temperature measurement system and temperature processing method are effective and efficient. Compared with the traditional manual way, temperatures obtained using the proposed system are more stable and accurate. [ABSTRACT FROM AUTHOR]

Summary: In this study, a conventional Ni/yttria‐stabilized zirconia (YSZ) anode and a new Cu‐CeO2‐YSZ anode structure were assembled in an attempt to combine the advantages of both structures for use in direct methane solid oxide fuel cells. For this purpose, only a limited region (≤20 μm) of NiO/YSZ was deposited at the boundary of the electrolyte to benefit from the superior catalytic activity of Ni in the cells, while the rest of the cell benefited from the Cu‐CeO2‐YSZ anode structure, which does not cause cracking reactions. First, the effects of different pore formers on the anode skeleton, as well as the interactions of the Ni‐Cu species in the anode skeleton, are discussed. Then, the NiO/YSZ‐interlayer‐containing button cells with different thicknesses (≤20) and different ratios of NiO (40 wt%, 50 wt%, and 60 wt%) were studied. After the examination of the cells, 2 model cells with outstanding performance and 2 additional internal reference cells, conventional Ni/YSZ and Cu‐CeO2‐YSZ, were scaled up, and performance analysis and long‐term stability studies were carried out. As a result, for solid oxide fuel cells with increased carbonization resistance (around 6% performance loss due to carbonization after 100‐hour stability testing) and 86.1% of the initial performance of the conventional Ni/YSZ anode structure, a 15‐μm‐thick 40 wt% NiO/60 wt% YSZ interlayer with a dual layer anode structure is proposed. [ABSTRACT FROM AUTHOR]

A thermal cracking experimental equipment of hydrocarbon fuels was built to study n-heptane pyrolysis and the effect of reaction conditions on this reaction process. The main species were measured and the change rules were analyzed on the range of temperature 873–1073 K and pressure 0.1–3.5 MPa. The total content of alkenes products was more than alkanes on this pyrolysis process. Compared to alkenes with same number carbons, the alkanes were more easy to decompose with temperature but more conducive to formation with pressure increasing. The content of ethylene is usually the most on above reaction conditions, but its descent is also the fastest with pressure increasing. A mechanism model of n-heptane pyrolysis (44 species and 166 reactions) was constructed and validated by experiments on different conditions. Compared with n-heptane oxidation detailed model of Version 3.1 from Lawrence Livermore National Laboratory (LLNL), the pyrolysis model present a better accordant with experiment results on a range of temperature and pressure. The kinetic reaction of n-heptane pyrolysis was analyzed with present pyrolysis model, and the pyrolysis reaction pathway for the main products was obtained. The formation of alkenes are mainly through C C bond dissociation reaction, especiallyβ-C dissociation, and small alkanes are formed mainly by radical metathetical or synthesis reaction, the former are endothermic reactions, but the latter are mostly exothermal reactions. The properties of some main reactions have a critical role for the change of product content with temperature and pressure, which is the main reason for the variety of products selectivity under different conditions. Pressure increased the pyrolysis residence time and mass density but it does not significantly affect the reaction energy, so its contribution to conversion rate of fuels thermal cracking is limited, although it changes the reaction pathway greatly. However, the temperature can increase obviously the reaction activation energy, even though the residence time and concentration is decreased, the conversion rate of n-heptane pyrolysis still increased. [ABSTRACT FROM AUTHOR]

Cement-sheath integrity is important for maintaining zonal isolation in the well. The annular-cement sheath is considered to be one of the most-important well-barrier elements, both during production and after well abandonment. It is well-known, however, that cement sheaths degrade over time (e.g., from repeated temperature and pressure variations during production), but the link between leak rate and the cause of cement-sheath degradation has not yet been established. In this paper, we have studied fluid flow through degraded cement sheaths. The degree of degradation of the cement sheaths varied from systematically connected cracks to real microannuli. The leak paths, created by thermal-cycling experiments, were imported into a computational-fluid-dynamics (CFD) simulation software. The pressure drop over the cement sheath was used as a boundary condition, and the resulting pressure-driven flow was studied using methane gas as the model fluid. The Forchheimer equation was used to estimate the effective permeability of the cement sheaths with defects. Our results show that the pressure-driven flow is complex and greatly affected by the geometry of the flow paths. A nonlinear pressure-buildup curve was observed for all experimental cases, indicating that Darcy's law was not validated. For homogeneous microannuli, the pressure-buildup curve was linear. The estimated effective permeability for all cases was observed to be orders of magnitude larger than that of a good cement sheath. [ABSTRACT FROM AUTHOR]

In order to improve the quality of bio-oil and reduce the coking and deactivation of HZSM-5 molecular sieve catalyst in the catalytic cracking of bio-oil upgrading process, Non-Thermal Plasma (NTP) assisted HZSM-5 technical scheme was proposed, online upgrading of rape straw vacuum pyrolytic vapors were conducted in a fixed bed reactor to verify the effectiveness of the technology. In the research, the influence of catalyzing temperature, catalyst bed height, discharge power on the physicochemical properties of refined bio-oil were studied, and the yield of refined bio-oil was regarded as evaluation index, response surface methodology was adopted to optimize upgrading processing parameters. Chemical composition of the refined bio-oil which was obtained under optimized parameters was analyzed by GC–MS, and using thermogravimetric analysis, the impact of NTP on catalyst anti-coking property was evaluated. Research results indicates that catalyzing temperature, catalyst bed height and discharge power have significance effect on yield and physicochemical properties of refined bio-oil. With the optimized processing parameters of 392 °C catalyzing temperature, 34 mm catalyst bed height and 23.7 W discharge power, the oxygen content, high heating value and pH of refined bio-oil were respectively 19.79%, 33.14 MJ/kg and 4.98. Compared with original HZSM-5 catalytic upgrading method, the quality of refined bio-oil was improved obviously, and the amount of catalyst coke deposit reduced from 5.88% to 2.14%, the feasibility of NTP assisted HZSM-5 online upgrading bio-oil was confirmed. [ABSTRACT FROM AUTHOR]

The present manuscript reviews state-of-the art models of hydrogen-assisted cracking (HAC) with potential for application to remaining life prediction of oil and gas components susceptible to various forms of hydrogen embrittlement (HE), namely, hydrogen-induced cracking (HIC), sulfide stress cracking (SSC), and HE-controlled stress corrosion cracking (SCC). Existing continuum models are compared in terms of their ability to predict the threshold stress intensity factor and crack growth rate accounting for the complex couplings between hydrogen transport and accumulation at the fracture process zone, local embrittlement, and subsequent fracture. Emerging multiscale approaches are also discussed, and studies relative to HE in metals and especially steels are presented. Finally, the challenges that hinder the application of existing models to component integrity assessment and remaining life prediction are discussed with respect to identification of model parameters and limitations of the fracture similitude, which paves the way to new directions for further research. [ABSTRACT FROM AUTHOR]

Internal pores and fractures inside oil shale undergo complex changes during pyrolysis in superheated steam. After a simulated in-situ pyrolysis in superheated steam, the pore characteristics of 30 oil shale samples from different zones between the injection and production wells were investigated using mercury intrusion porosimetry (MIP). The results showed that the porosity of oil shale exceeded 27.65% in each position of horizontal fractures. In different types of pores, the proportions of mesopore (0.1 µm < d ≤ 1 µm) and micropore (d ≤ 0.015 µm) were the largest and the smallest, respectively. Moreover, mesopores outnumbered micropores. The pore structure of pyrolyzed oil shale after convection heating was complex. After the pyrolysis in superheated steam, the proportion of the oil shale ore body with a porosity ranging from 23 to 31% was 74.95% of total. This finding proved that oil shale was transformed from dense rock to a porous medium under the effect of superheated steam. [ABSTRACT FROM AUTHOR]

Based on the characteristics of maximizing iso-paraffins (MIP) process and industrial data, an 8-lump kinetic model for MIP process is developed. And the 47 kinetic parameters of the model are calculated by Runge-Kutta method and genetic algorithm. It is seen that kinetic parameters show good consistence with the reaction mechanism of catalytic cracking. The average relative errors between calculated values and real values of product distribution are all below 5%. Then the model is modified by 14-7-5 type of back propagation (BP) neural network. As a result, the product distribution can be predicted more accurately by the hybrid model. Therefore, the combination of lump model and neural network can provide a new direction for simulation and optimization for heavy oil catalytic cracking. [ABSTRACT FROM AUTHOR]

The catalytic cracking of isopropylbenzene was investigaded over hybrid ZSM-12/MCM-41 and HZSM-12/MCM-48 micro-mesoporous materials, in order to verify the effect of the acid site of the accessibility of mesoporous channels combined with the acid sites into the zeolite. The hybrid materials were synthesized by the hydrothermal method using the template mechanism. The obtained materials were characterized by X-ray diffraction and BET isotherms using nitrogen adsorption-desorption at 77 K. The X-ray diffraction patterns presented characteristic peaks of the microporous and mesoporous phases. These analysis revealed the formation of ordered hexagonal MCM-41 or cubic MCM-48 mesoporous phases, associated with the ZSM-12 structure. In order to generate acid sites, the materials were ion exchanged with ammonium chloride solution. The calcined hybrid materials were tested as catalyst for cracking of isopropyl-benzene, using a fixed bed reactor at 450 oC and nitrogen gas. The catalytic tests showed that the HZSM-12/AlMCM-41 and HZSM-12/MCM-48 hybrid materials have potential for use in cracking reactions, bening more active than the zeolite or the M41S alone. The catalytic activities of the hybrid materials can be associated with a synergistic effect between the acid sites present on the zeolitic phase and the mesoporous phase. In order to verify how the structure of the hybrid materials may affect and control their catalytic performances, the results were compared with HZSM-12 physically mixed with MCM-41 and MCM-48. [ABSTRACT FROM AUTHOR]

This work deals with an efficient two-step thermal upgrading process for converting extra-heavy fuel oil to light olefins (ethylene, propylene, and butenes) and fuels (gasoline and diesel fuel). In the first step, mild thermal pretreatment was implemented at different temperatures (360-440 °C) in the liquid phase to obtain a more suitable feedstock for an olefin production unit. Thanks to this cost-effective pretreatment, the upgraded feedstock demonstrated considerable flowability and crackability compared to the initial fuel oil, making the subsequent vapor-phase operation easier to handle at temperatures as high as 800 °C with no severe operational impediments. The quantitative ¹H and 13C NMR studies shed light on the enhanced features of the thermally treated feedstock toward lighter and more valuable products. As a result, remarkable olefin production (74.7 or 55.1 wt % light olefins based on the upgraded or the original feedstock) was accomplished in this two-step process. The process could be alternatively stopped at the first stage for maximum liquid fuels (69.3 wt %) with gasoline as the larger constituent. The detailed kinetic investigations of the thermal decomposition of the feedstock using several reliable approaches revealed that the activation energy predictions (42.3-272.9 kJ/mol) by the Kissinger-Akahira-Sunose method almost perfectly matched the trend of a reference Starink model over the whole range of conversion. All model-free methods correlated with a coefficient of determination above 97.9%. Avrami's theory was further applied to determine the reaction order, and the values were slightly smaller than those from a five-lump kinetic model of the semibatch operation. However, the apparent activation barrier in the reactor was in good correspondence with the range from the microscale nonisothermal decomposition. [ABSTRACT FROM AUTHOR]

Crude oil is becoming more and more difficult to refine because of increasingly large heavy oil molecules. Increased external surface of catalysts contributes to promoting precracking of heavy or extra-heavy oil molecules. Flowerlike hierarchical Y zeolite with considerably increased external surface was synthesized without using any organic templates by a hydrothermal procedure. Because the isolated nanoparticles are unstable, the primary nanocrystals gather via self-assembly into loose aggregates. The inner crystals, which act as the "pistils", are difficult to grow because of the confined spaces, while the outer crystals in the aggregates can further grow and form the oriented sheet "petals". The increased exterior surface offers the catalysts dramatically elevated conversion when tested in the catalytic cracking of triisopropylbenzene. The result also suggests that the activity of the catalysts in large reactant involved reactions may generally depend on its external surface properties. [ABSTRACT FROM AUTHOR]

Petroleum coke is often shortened as pet coke. Petroleum coke or pet coke is a product obtained from oil of all kinds during the oil refining process. Petroleum coke is a carbon-rich solid originating from petroleum refining and is obtained by cracking process. Petroleum coke is a byproduct of the coking unit, a residual fuel upgrader. The coke quality depends on the crude oil processed in refinery. The mixture of oil, solids and water deposited at the bottom of the storage deposit is known as waste oil sludge. Oil sludge is one of the solid wastes produced in petroleum refinery and it is a complex emulsion composed of various petroleum hydrocarbons, heavy metals, solid particles, and water. As a result of the refining process of crude oil, the contaminated sludge is biodegraded and converted into waste products that damage the environment and human health. In the coke processing, the assessment of oil sludge fraction is based on the principle of heating to high temperatures and the removal of light fractions from the breakdown. If the oil sludge initially contains low levels of sulfur and metal, the resulting petroleum coke is then calcined before use. The high quality needle type coke produced on convenient conditions in the coking unit. [ABSTRACT FROM AUTHOR]

Figuring out the mining-crack-evolution characteristics of overburden strata is very important to roof control, gas drainage, disaster prevention and high efficient mining. In order to obtain the mining-crack-evolution characteristics of overburden strata in deep coal mining with large dip, in this study, No.1221 coal mining face of Zhao coal mine is chosen as the research object to establish an in-house experiment system of similarity simulation. The experiments could measure the stress and displacement of overburden strata, which can provide useful information to investigate the mining-crack-evolution characteristics, displacement variations and movement characteristics of overburden strata associated the coal mining face. Experimental results show that with the advancing of coal mining face, the scope of gob increases gradually, and formation of the false roof of overburden strata basically reflects the evolution process of collapsing. The overburden strata weight is constantly transferred to the front and rear of coal mining face, which forms the supporting pressures on both sides of coal pillars, and causes the gangue's collapsing in gob. The large dip of coal seam results in pressure disequilibrium in stress-increasing zone. Thus, the stress on the underside of gob becomes larger and larger, while the stress on upper side of gob decreases. The strata separation appears in the overburden strata of roof. Pressure-relief zone is mainly concentrated in the side of outlet roadway. Along the inclination direction of coal mining face, the crack development and strata separation are obvious, which create the passages for gas flow and migration. The similarity simulation results provide fundamental information for better understanding those mining-crack-evolution characteristics of overburden strata, which has become more and more important to control the roadway stability in coal mining and optimize the layout of gas drainage boreholes for improving mining safety. [ABSTRACT FROM AUTHOR]

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The main goal of this research is modeling and simulation of ethylene production through naphtha thermal cracking in a coil furnace reactor. The naphtha cracking and decoking processes are modeled based on the mass, energy and momentum balance equations considering a detail kinetic model at pseudo-dynamic condition. To develop a reliable and applicable model, a detail thermal model is considered to predict tube skin temperature. To prove accuracy of developed model and considered assumptions, the simulation results are compared with the plant data. In addition, the results of coke burning in the decoking cycle by mixture of air and steam are presented. It is appeared that ethylene production decreases during the process run time gradually. The simulation results proved that increasing feed temperature, feed pressure and combustion chamber temperature during the process run time is a practical solution to maintain production capacity at an acceptable level. Finally, the optimal operating condition of thermal cracking process is calculated during the process run time based on the time variant feeding policy to achieve maximum ethylene production capacity. It is appeared that applying optimal condition on the system could increase ethylene production capacity from 15.31 ton.h-1 to 15.49 ton.h-1. [ABSTRACT FROM AUTHOR]

Proppant embedment in hydraulic fracturing can reduce remarkably the fracture width and thus damage the fracture conductivity. This paper describes a study of the proppant embedment mechanism. Two groups of experiments were carried out. A proppant embedment mechanism was proposed. An analysis showed that proppant embedment is not an elastic process but could be a plastic or even failure process depending on the surface microstructure of the formation core. [ABSTRACT FROM AUTHOR]

Oxidation studies were performed on solution-annealed Alloy 600 in high-temperature steam at 400 °C and in simulated pressurized water reactor primary water at 320 °C under environmental conditions where this alloy is known to be susceptible to intergranular stress corrosion cracking. Advanced analytical transmission electron microscopy characterization and detailed scanning electron microscopy analysis highlighted extensive preferential intergranular oxidation as well as enhanced Cr and O diffusivities associated with this oxidation. These findings, as well as the preferential intergranular oxidation susceptibility and diffusion-induced grain boundary migration, are discussed in terms of their roles as precursors to stress corrosion cracking. [ABSTRACT FROM AUTHOR]

Abstract: The monomolecular cracking rates of propane and n‐butane over MFI, CHA, FER and TON zeolites were determined simultaneously with the coverage of active sites at reaction condition using IR operando spectroscopy. This allowed direct determination of adsorption thermodynamics and intrinsic rate parameters. The results show that the zeolite confinement mediates enthalpy–entropy trade‐offs only at the adsorbed state, leaving the true activation energy insensitive to the zeolite or alkane structure while the activation entropy was found to increase with the confinement. Hence, relative cracking rates of alkanes within zeolite pores are mostly governed by activation entropy. [ABSTRACT FROM AUTHOR]

Typically, cracking can be observed on the rubber surface when it is stretched and exposed to the ozone. Ozone-induced stress cracking is considered a problem as it contributes to diminishing the appearance and serviceability of rubber products. Ozone concentration form cracks which cause potential failure in the rubber. This study investigates the influence of ozone exposure and discusses most of the effects resulting from the ozone attack. Water serves a barrier and protects rubber from the ozone attack. Many cracks formed on the rubber surface at a high strain compared to that of a low strain. The distribution of crack lengths represents a complex function of time and strain. The chemical reaction of ozone proceeds in the absence of strain which results in a shiny appearance and is tacky due to uniform occurrence of ozonolysis on the rubber surface. [ABSTRACT FROM AUTHOR]

The ethylene cracking furnace system is crucial for an olefin plant. Multiple cracking furnaces are used to convert various hydrocarbon feedstocks to smaller hydrocarbon molecules, and the operational conditions of these furnaces significantly influence product yields and fuel consumption. This paper develops a multiobjective operational model for an industrial cracking furnace system that describes the operation of each furnace based on current feedstock allocations, and uses this model to optimize two important and conflicting objectives: maximization of key products yield, and minimization of the fuel consumed per unit ethylene. The model incorporates constraints related to material balance and the outlet temperature of transfer line exchanger. The self-adaptive multiobjective teaching-learning-based optimization algorithm is improved and used to solve the designed multiobjective optimization problem, obtaining a Pareto front with a diverse range of solutions. A real industrial case is investigated to illustrate the performance of the proposed model: the set of solutions returned offers a diverse range of options for possible implementation, including several solutions with both significant improvement in product yields and lower fuel consumption, compared with typical operational conditions. [ABSTRACT FROM AUTHOR]

Natural fractures commonly exist in unconventional reservoirs such as shale and tight gas sandstone, which are mostly cemented (or sealed) with minerals and not able to contribute to reservoir storage or rock permeability. However, during hydraulic fracture stimulation, these cemented natural fractures will be encountered and influence hydraulic fracture geometry greatly and, thereby, gas production. In this work, hydraulic fracture propagation in rock with cemented natural fracture is investigated using our recently developed and validated hydro-mechanical coupled LBM-DEM model. The numerical results show that both the strength ratio (between cemented natural fracture and host rock) and the approach angle (between hydraulic and cemented natural fracture) significantly affect the hydraulic fracture propagation. A larger strength contrast or a smaller approach angle will be more conducive to deflection, which is consistent with experimental observation. For rocks with weakly cemented natural fractures, deflection is mainly caused by shear failure in weakly cemented fracture. However, for rocks with strongly cemented natural fractures, deflection happens accompanying with tensile failure in host rock along the cement wall, which cannot be captured by the previous numerical models where the cemented natural fracture is treated as a bonded interface. In addition, complex fracture network is more easily formed if multiple weakly cemented natural fractures are orthogonal to the hydraulic fracture propagation direction. [ABSTRACT FROM AUTHOR]

The hydrocarbon resources of shale gas and tight oil have made a significant impact on North American energy reserves over the past decade. The production of so-called “unconventional” natural gas from U.S shales like the Barnett, Haynesville, Fayetteville, Marcellus, and Utica, and Canadian shales like the Muskwa, Montney, and Duvernay have saturated North American gas markets, boosted Canada's exports, and turned the U.S. into a net exporter of natural gas. Tight oil production from the Bakken Shale has made important contributions to the economy of the Canadian province of Saskatchewan. North Dakota has become the second largest oil producing state in the U.S. thanks to production from the Bakken. It trails only the state of Texas, which maintains first place because of equally prolific hydrocarbon liquids production from the Eagle Ford Shale and shales in the Permian basin. It is difficult to overstate the importance of these shale gas and oil resources to the U.S., North American, and world energy economies. North American shale development blossomed in the United States between 2005 and 2010, driven by high natural gas and oil prices, the availability of favorable lease positions on shale plays, and the application of drilling and stimulation technology that could successfully produce commercial quantities of hydrocarbons from these formations at economical costs. Development in Canada began a bit later, and some development has also taken place on shales in Mexico. Many people who express surprise at the apparent “overnight” success of shale gas and oil production were simply not paying attention. The truth is that a historic and protracted engineering struggle was required to identify, modify, and apply the right technology for economically-viable production. Modern assessments of the resource potential of these rocks began in the late 1970s, as did the first systematic engineering attempts to drill directional wells and hydraulically fracture shale. Success was elusive for nearly two decades, however, until the right combination of economics and technology came along. The ability of some visionary people to recognize the applications of that technology led directly to the current success of shale gas and tight oil production. Other countries considering development of their own shale resources are looking to the North American example for leadership. The success of shale resource development has not been without controversy. Public fear of the hydraulic fracturing process, or “fracking” has been amplified by shale gas opponents, leading to restrictions against shale development in many areas, and outright bans in some locations like New York and Quebec. The “boomtown” nature of the early development, and the lack of definitive environmental risk data has added to the negative perceptions, resulting in a backlash against some exploration and production ventures. Researchers have been gradually reducing the amount of uncertainty with respect to environmental risks, and as operators have gained more experience, the frequency of incidents has fallen. Many operators now recognize that obtaining a “social license” from the community is a necessary first step for successful shale gas development. [ABSTRACT FROM AUTHOR]

Additives to a zeolite-containing cracking catalyst were synthesized and studied in order to enhance the resistance to the poisoning effect of nitrogen compounds (in particular indole) upon cracking of n-undecane as the model FCC hydrocarbon. The additives were represented by acid-activated clays and mixed oxides. The activation of clays in the catalyst by 5% sulfuric acid solutions was shown to enhance the resistance to nitrogen. The introduction of Mg, Al – mixed oxides in the catalytic system in the amount of 10 wt% increased its activity and resistance to indole. The highest resistance was observed for the systems containing magnesium‑aluminum oxides with a Me 2 + to Me 3 + molar ratio equal to 0.5: 1. Cobalt modification of these mixed oxides enhanced the activity and nitrogen resistance of the cracking catalysts. Use of such nitrogen-resistant catalysts will allow cracking of heavy raw materials. [ABSTRACT FROM AUTHOR]

A common failure in a certain type of gas turbine, observed during the first periodic inspection, is radial cracks in the tip plate of gas fuel nozzles. Here, each gas turbine has 18 nozzles. In all nozzles and in all similar units, these cracks of lengths ranging from 1 mm to a maximum of 14.5 mm are observed. As prescribed by the manufacturer, the defective part must be removed and replaced by welding and machining of a new one. But this problem is repeated and observed in the next periodic visits, and in all units. Depending on the number of nozzles in each gas turbine unit and the number of units in total, these repairs are very expensive and time-consuming. In this paper, the failure is analyzed and the causes of the cracks in the nozzles are investigated. Studies show that the main causes of nozzle failure are residual stresses caused by welding and thermal stresses caused by the start-up and shutdown processes. According to results, a solution has been proposed to release these residual and thermal stresses. After the implementation of this method in 1998, no more failure has been reported by the repair team, which proves the effectiveness of this solution. Since this paper has been prepared based on technical reports from the years between 1996 and 1998, the cited references of this paper are these technical reports. [ABSTRACT FROM AUTHOR]

Acidic bentonite clay was obtained through surface modification of bentonite clay using hydrochloric acid as acidic precursor to increase the acidity of the bentonite. The modified catalyst was examined via X-ray fluorescence (XRF), XRD analysis, Brunauer Emmett and Teller surface area (BET), FTIR analysis and temperature-programmed desorption (TPD) analysis. XRF analysis showed that the acid modification of bentonite clay results in an increase in the silica content and lower abundance of metal oxides, due to the dissolve of Fe 2 O 3 , MnO, CaO, Na 2 O. Ca 2+ , Na + cations from the interlayer and octahedral sheets. FTIR spectroscopy showed that the acid activation decreased the intensity of the absorption bands at 915, 875 and 836 cm −1 which arise from the binding modes of OH groups. NH 3 -TPD analysis showed a considerable increase in the moderate and strong Bronosted acid cites on the modified bentonite compared to the native clay. The modified bentonite was evaluated as economic and efficient heterogeneous catalyst in catalytic cracking process of two nonedible vegetable oils to obtain the corresponding biofuels at moderate processing temperature of 250–280 °C. It was observed that the catalytic conversion was preceded under mild temperature and obtained efficient biofuels with approved physical and fuel properties according to ASTM specifications. The role of the catalyst ratio was considerable on the yield percent and the properties of the obtained biofuels. The catalytic activity-reaction mechanism was discussed based on NH 3 -TPD analysis. [ABSTRACT FROM AUTHOR]

Abstract: Among the options for clean energy production, the gasification process is receiving increasing attention as it offers the best combination of investment and value of produced electricity compared to other methods. An Aspen Plus model of co‐gasification of biomass and coal with in situ CO2 capture was developed to evaluate its potential for hydrogen production and cracking of organic impurities, i.e., tars. The effects of some critical operational variables on gas composition and yields of hydrogen gas and tar were investigated. The obtained results indicate that the fuel particle size plays a minor role in the process; smaller particles favor the conversion of tar and production of more hydrogen gas. [ABSTRACT FROM AUTHOR]

The global production of residual feedstock has reached 150 million metric tons per annum and is expected to increase in the future due to the progressively increasing heavier nature of the crudes. Petroleum coke (petcoke), one of these residues, is a solid-rich carbon typically produced during the upgrading of heavy oil and delay coking of vacuum residue in the refinery. Finding an alternative technique to treat this massive amount of petcoke is highly needed as the conventional processes like gasification and combustion have limitations in terms of efficiency and environmental friendliness. In this study, an oxy-cracking technique, which is a combination of cracking and oxidation reactions, is conducted as an alternative approach for petcoke utilization. The reaction is conducted in a Parr reactor where petcoke particles are solubilized in an aqueous alkaline medium and partially oxidized under mild operating temperature and pressure. Several operating conditions on petcoke oxy-cracking were investigated, such as temperature, oxygen pressure, reaction time, particle size and mixing rate to optimize the solubility and selectivity of oxy-cracked products. The results showed that the temperature and the residence time are the two major important parameters that affect the reaction conversion and selectivity. This enabled us to propose a reaction pathway based on the radical mechanism to describe the kinetic behavior of petcoke. Reaction kinetics indicated that petcoke oxidation undergoes a parallel-consecutive reaction in which an oxidative decomposition took place in the first step producing different oxidized intermediates. The oxy-cracked petcoke was characterized by FTIR, XPS and NMR analyses. The oxy-cracked products were found to contain carboxylic, carbonyl, phenolic, and sulfonic functions. Moreover, the elemental analysis showed that most of the metals remained in the residue, suggesting that the proposed technique could be employed for petcoke demineralization. [ABSTRACT FROM AUTHOR]

A novel strategy that combines steam reforming of bio-oil and recovering waste heat from blast furnace (BF) slag was proposed, and the thermodynamic characterizations of steam reforming of bio-oil model compounds recovering waste heat from BF slag for hydrogen production were investigated. When temperature ranged from 600 to 700 °C, hydrogen yield and its component reached maximum, about 100 mol kg−1 bio-oil model compounds and 70%, respectively. The higher mole ratio of steam to carbon in bio-oil (S/C), the higher hydrogen yield and its component were obtained, but according to the practical process, the most suitable S/C was 4. The ordinary pressure (1 bar) was considered as the optimum pressure for steam reforming of bio-oil model compounds recovering waste heat from BF slag. At lower temperatures (below 500 °C), BF slag could promote hydrogen yield, but it slightly decreased equilibrium yield of hydrogen at the optimal conditions. Besides, BF slag could promote hydrogen component at lower temperatures (below 600 °C), but it had little effect at the optimal conditions. Solid carbon should be reduced during steam reforming of bio-oil compounds recovering waste heat from BF slag. [ABSTRACT FROM AUTHOR]

We determine the chemical changes associated with viscosity reduction when heavy oil is cracked in subcritical water. The viscosity reduction has a temperature threshold for onset of 290 °C-this suggests an enhanced acid cracking regime associated with the maximisation of water dissociation at these conditions aided by the already increased solubility. The mean molecular weight is reduced by nearly 50%. Oxygen and sulphur are reduced by about half of this-either by expelled gas effluent (H2S) or by conversion into mono-aromatic base sulphur-containing structures. The amount of lower branched paraffins is increased. [ABSTRACT FROM AUTHOR]

The effect of temperature on the cracking of pond acid tar and acid tar neutralized with lime has been studied. The formation of H2S or SO2 is determined by the amount of sulfuric acid in the tar. Liquid hydrocarbons obtained from neutralized acid tar are characterized by low sulfur content. [ABSTRACT FROM AUTHOR]

Fracking to approach permeability enhancement is indispensable to enhance coalbed methane recovery, which can significantly reduce greenhouse gas emissions and produce substantial clean energy. To access efficient fracking, samples of Permian low permeable coal reservoir were cracked into different sizes or scales of blocks and particles with liquid nitrogen cryogenic freeze fracturing (FF) by maximizing the underlying heterogeneity of coal. To investigate the crack efficacy, this study systematically examined the permeability evolution and mesoscopic cracking behaviors of coal with different water contents and cleat–fracture systems in the context of cryogenic FF. Results showed that the permeability enhancement and microcracking tended to occur with increasing water content of coal sample; and the efficacy of cryogenic FF on the tighter coal sample was more remarkable. However, the permeability does not strictly increase with the cycles of cryogenic FF and has a close relationship with water content, structural plane direction, efficacy of cryogenic FF, and porosity compaction. The mesoscopic cracking behaviors indicate that numerous smaller pores are iteratively, not strictly sequentially, cracked and become connective in this process. The permeability evolution of coal sample is identified as significantly associated with the mesoscopic cracking behaviors. Notably, the first cycle of cryogenic FF acted on the detected several scales of pores and micro fissures, and partially caused these structures to be opened and interconnected to be permeable. Two main changes were observed in the microcracking of the coal samples in this study: 1) nonuniform shrinkage deformation and micro fissure expansion; and 2) pores opening mostly in the macropore and mesopore scale. It is reasoned that thermal cracking and intermittent opening of seepage pores due to the phase transition of free water in pores or micro fissures ultimately contribute to the permeability enhancement in low permeable and heterogeneous coal. [ABSTRACT FROM AUTHOR]

In considering a site for gas storage, it will be important to evaluate the effects of gas storage on the formation, so as to minimize the risk of a breach occurring in the system. Gas injection will result in an increase in formation fluid pressure, especially around the injection source, which in turn results in redistribution of the stress field. The induced deformations within the reservoir can potentially result in a damage zone within the caprock formation. This mechanical failure may involve shear along many of the existing fractures or creation of new fractures that reduce the sealing properties of the caprock system. The main objective of this paper is to develop a model to estimate the growth and extension of cracks in the caprock. In order to achieve this, the smeared crack approach is used to model the process of cracking in the caprock. Smeared cracking is a continuum approach for damage mechanics which is based on the idea that a crack is modeled by modifying the strength and stiffness of the material. The main model presented in this paper has three sub-models, which are the reservoir model, the caprock model and the smeared crack model. The reservoir model is a simplified coupled hydro-mechanical model that numerically simulates the radi al fluid flow and analytically estimates the associated stress and strain within the reservoir. The results of the reservoir model are used as boundary conditions for the caprock model that estimates the stress and strain within the sealing caprock due to the deformation of the reservoir. Using the calculated stress and strain, the smeared crack model predicts the growth and extension of cracks within the caprock. The caprock is assumed to be initially crack free and impermeable. The developed model is then used to study the Yort-e-shah aquifer caprock in Iran to predict the growth and extension of cracks. [ABSTRACT FROM AUTHOR]

The direct cracking of crude oil is an interesting option for producing cheaply large amounts of petrochemicals. This may be carried out with catalyst and equipment similar to that of catalytic cracking, but at a temperature range between that of standard catalytic cracking and steam cracking. Thermal cracking will play a role in the conversion, but is rarely disclosed in experimental or modeling work. Thus, a crude oil and its fractions were thermally cracked and the products yields were modeled using a 9 lumps cracking scheme. It was found that heavy fraction cracks twice as fast as diesel fraction and ten times faster than gasoline fraction, with activation energies in the 140–200 kJ/mol range. Selectivity to ethylene, propylene and butenes were found similar in the operating range explored. [ABSTRACT FROM AUTHOR]

Purpose The cracking of a reinforced concrete lining has a significant influence on the safety and leakage of pressure tunnels. This study aims to develop, validate and apply a numerical algorithm to simulate the lining cracking process during the water-filling period of pressure tunnels.Design/methodology/approach Cracks are preset in all lining elements, and the Mohr−Coulomb criterion with a tension cutoff is used in determining whether a preset crack becomes a real crack. The effects of several important factors such as the water pressure on crack surfaces (WPCS) and the heterogeneity of the lining tensile strength are also considered simultaneously.Findings The crack number and width increase gradually with the increase in internal water pressure. However, when the pressure reaches a threshold value, the increase in crack width becomes ambiguous. After the lining cracks, the lining displacement distribution is discontinuous and steel bar stress is not uniform. The measured stress of the steel bar is greatly determined by the position of the stress gauge. The WPCS has a significant influence on the lining cracking mechanism and should not be neglected.Originality/value A reliable algorithm for simulating the lining cracking process is presented by which the crack number and width can be determined directly. The numerical results provide an insight into the development law of lining cracks and show that the WPCS significantly affects the cracking mechanism. [ABSTRACT FROM AUTHOR]

A kinetic model of the isothermal initiated cracking of tar has been developed, and parameters of the reactions have been found. A computer model of isothermal thermo-oxidative cracking of tar is implemented to determine kinetic constants, and a criterion for mismatching the calculated and experimental data is minimized. The kinetic simulation of the process has been carried out in isothermal regime so that the parameters that allow for increase in yield of target products have been determined. [ABSTRACT FROM AUTHOR]

According to the chemical, carbon isotopic, and hydrogen isotopic compositions and 3 He/ 4 He ratios of 127 natural gas samples, the natural gas in the Tarim Basin is mainly composed of gaseous alkanes dominated by methane. The contents of the gaseous alkanes decrease with the increase of their carbon numbers. The δ 13 C values of CH 4 , C 2 H 6 and C 3 H 8 in the platform area of the Tarim Basin vary in the range of −54.4‰∼-24.4‰ (an average value of −39.2‰), −43.1‰∼-26.7‰ (an average value of −36.1‰) and −37.9‰∼-21.6‰ (an average value of −31.8‰), respectively. The overall carbon isotopic composition of the alkanes follows the trend of δ 13 C 1 < δ 13 C 2 < δ 13 C 3 < δ 13 C 4 and in some cases varies with δ 13 C 1 >δ 13 C 2 or δ 13 C 3 > δ 13 C 4 . The lower carbon isotope values of methane (δ 13 C 1 < δ 13 C 2 ) may be attributed to thermal sulfate reduction (TSR), and the higher propane value (δ 13 C 3 > δ 13 C 4 ) was caused by the mixing of the natural gases of the same genetic type formed at different stages. The methane hydrogen isotopes (δ 2 H-C 1 ) of the natural gases in the Tarim Basin are in the range of −195‰∼-122‰ with an average value of −156‰. The 3 He/ 4 He ratios of the natural gases are in the range of 2.3 × 10 −8 ∼66.8 × 10 −8 , suggesting that there is no deep mantle-derived gas in the platform area of the Tarim Basin. The carbon isotope fractionation of alkane gases (δ 13 C 2 <−28‰ and δ 13 C 3 <−25‰) indicates that the natural gas in the platform area of the Tarim Basin is oil-type. The modified plots of lnC 1 /C 2 vs. lnC 2 /C 3 and C 2 /C 3 vs. δ 13 C 2 -δ 13 C 3 of the natural gases indicate that the oil-type gas in the Tarim Basin has different predominant formation processes, including kerogen-cracking, oil-cracking, oil- and gas-cracking, secondary gas-cracking and mixing of the kerogen-cracking and oil-cracking gases. The gas evolved from gas-cracking gas, to oil- and gas-cracking gas and oil-cracking gas along the direction from the west side of the Manjar Sag to the central Tarim Basin. The natural gases in some areas of Tazhong are the mixtures of the kerogen-cracking and oil-cracking gases. [ABSTRACT FROM AUTHOR]

In this paper, we proposed an alternative way to estimate volumetric vapour: liquid ratio of gaseous or light-petroleum inclusions without fluorescence using regularly-shaped inclusions to estimate volumetric vapour: liquid ratios through geometric methods. The method was applied to the inclusions from the rock samples of the Lower Triassic Feixianguan and Jialingjiang Formations, NE Sichuan (China). The trapping pressures of inclusion fluids were calculated by integrating PVT simulation software, volumetric liquid: vapour ratios determined by the proposed method and homogenization temperatures measured by microthermometry. Fluid densities and gas-oil ratios (GOR) were also estimated. The estimated trapping pressures and temperatures are slightly lower for the Jialingjiang formation (29.69–31.33 MPa, 93.5–105.2 °C) than for the Feixianguan Formation (31.02–34.38 MPa, 98–148 °C), and the trapping time of the inclusions in the Jialingjiang Formation and Feixianguan Formation were estimated at about 173–170 Ma and 178-168 Ma, respectively. The distribution of high pressures correlates with the presence of pyro-bitumen in the reservoir rocks, suggesting the migrated fluid is derived mainly from the secondary cracking of oil. The modeled fluid density and GOR correspond to a typical light oil or condensate, suggesting an origin for the trapped hydrocarbons as an intermediate product in this process. [ABSTRACT FROM AUTHOR]

Nowadays, the time is coming for development of oil deposits with the so-called hard-to-recover reserves (HRR). Particularly relevant and important at this time are the fundamental issues of the formation of hydrocarbon deposits. To understand how the most cost-effective way to extract heavy oil from clay-bituminous sediments, it is necessary to know the nature of the process of the formation of hydrocarbons. In the present work, experimental studies confirming the influence of electromagnetic fields on the change in the fractional composition of oil and fraction of heavy naphthenic hydrocarbon fractions are considered, as well as examples of natural phenomena that could affect the rapid, jumping formation of light oil deposits by changing the electromagnetic field of our planet. The object of research is the change in the fractional composition of oil under the influence of an electromagnetic field of frequency 50 Hz and magnetic induction of about 0, 81 T, as the subject of research is oil Bazhenov horizon, which according to many scientists is oil generating in Western Siberia. The purpose of the study was to evaluate the change in heavy oil fractions under the influence of an electromagnetic field. [ABSTRACT FROM AUTHOR]

The paper presents ways to determine the cracking pressure and the gradients corresponding to these pressures. The influence of pressure and cracking gradients on the secondary voltage state around vertical probes is also analyzed. [ABSTRACT FROM AUTHOR]

Since the discovery of petroleum as a source of raw materials for many processes, many techniques able to convert it into different types of products have been developed. One of these methods is thermal cracking, which is based on heating the initial mixture with the purpose of dividing long carbon chains into small chains. In this way, the economic value of the stream highly increased. The reaction of molecular breakdown or decomposition is carried out in a furnace reactor at high temperatures. In order to provide energy to the stream and to increase his internal energy, the equipment uses methane as fuel. The resultant mixture is cooled to promote phases separation inside a splitter. The thermodynamic properties of the system are defined using Chao Seader model and kinetic reaction. The temperature in the furnace was studied to increase the isobutane mass fraction at the end of the reaction. Two sensibility analysis were realized, in the furnace-reactor and in the cooler pre-stripper, to determine their optima! points. In the first case, a temperature of 793.15 K was determined as optimal point to achieve an adequate conversion into isobutane. In the second case, the behavior of the inlet feed temperature in the stripper was obtained. The stripper operation was defined in 6 stages. The inlet stream should be fed at the third stage with a temperature of 400.0 K. At this point, the use of the reboiler is not necessary. [ABSTRACT FROM AUTHOR]

To prevent the occurrence of thermal runaway accidents in semibatch reactors (SBRs), it is desirable and practicable to develop criteria that can distinguish between the safe and runaway operating regions. In this article a new safety criterion, namely, the adiabatic criterion, has been developed for SBRs in which liquid homogeneous as well as liquid-liquid heterogeneous reactions with arbitrary reaction orders occur. It states that an SBR is operated in the potential runaway situation if the value of the adiabatic criterion exceeds zero at a segment of the reaction path. Numerical results show that the adiabatic criterion is more conservative than the two other criteria (divergence criterion and target temperature criterion). However, the adiabatic criterion is not suitable to reactions with autocatalytic behaviors. Also knowledge of activation energies and reaction enthalpies is necessary to utilize the adiabatic criterion. [ABSTRACT FROM AUTHOR]

The article presents the results of processing heavy oil residues initiated by atmospheric oxygen. We found that the introduction of a small amount of atmospheric oxygen (2–6%) in the thermo cracking reactor (thermo-oxidative cracking) significantly increases the yields of light fractions. E.g. A thermo cracking of vacuum residue (visbreacking) with the air supply to the soaker camera gives twice more light fractions than traditional visbreacking process (36% of petrol and diesel fractions compared to 10–15% in conventional process). Thermo-oxidative cracking of atmospheric residue gives up to 60% of light fractions. In order to obtain a mathematical description of the process needed for its subsequent industrial implementation we conducted experiments on thermo-oxidative cracking of atmospheric and vacuum residues in a continuous flow reactor with a wide variation of the process parameters. Based on the analysis of the experimental data a common scheme for thermo-oxidative cracking, a mathematical model of the process and its parameters were established. The model adequately describes all the experimental data obtained in the temperature range 430–460 °C, pressure 2–8 atm, retention times 4–33 min and relations oxygen/raw material 0,9–2,5 % wt. Industrial implementation of thermo-oxidative cracking needed just minimal modification of the existing thermal installations through the organization of air supply in the soaker chamber. This modification will increase the output of light fractions in the thermal processing heavy oil residues in 2–3 times with minimal capital investments. [ABSTRACT FROM AUTHOR]

This work aims to investigate the importance of biomass char and the metal oxides in the ash in tar cracking during the volatile-char interactions. Experiments were carried out in a two-stage fixed reactor, and corncob, one typical agricultural biomass rich in potassium, was chosen as raw material. Results showed that char and char-supported potassium catalysts have good activity for tar elimination due to the good absorbability of char and catalytic property of potassium. In particular, tar conversion efficiency can reach 95.8% by using 1.5 K-char catalyst at 700 °C. The reforming reactions can be significantly enhanced during the volatile-char interactions in the presence of char and char-supported potassium catalysts. As a result, the syngas yield increased significantly with increasing temperature and supported K, particularly the combustible gases including H, CO and CH. Physical and chemical structure of char changed due to reforming reactions related to the carbon, while the content of potassium was almost unchanged. [ABSTRACT FROM AUTHOR]

The thermal evolution of phytol in thecatalytic environmentsof reduction, montmorillonite catalysis and illite catalysis has been investigated. The results show the following: (1)Montmorillonite and illite facilitate the defunctionalization and further cracking of phytol. (2) Pristane and phytane can no longer serve as effect biomarkers at the high thermal evolution stage due to loss of thermostability. (3) Ratios of pristane/phytane greater than 1derive from reduction and montmorillonite catalysis environments. However, the ratio of pristane/phytane was less than 1 under the condition of illite catalysis, which has not been shown before. [ABSTRACT FROM PUBLISHER]