Showing papers in "Energy & Fuels in 2017"
TL;DR: In this paper, the authors report the first offshore methane hydrate production test conducted at the eastern Nankai Trough and show key findings toward future commercial production, which indicates that hydrate saturation reaches 80% and permeability in the presence of hydrate ranges from 0.01 to 10 mD.
Abstract: Marine methane hydrate in sands has huge potential as an unconventional gas resource; however, no field test of their production potential had been conducted. Here, we report the world’s first offshore methane hydrate production test conducted at the eastern Nankai Trough and show key findings toward future commercial production. Geological analysis indicates that hydrate saturation reaches 80% and permeability in the presence of hydrate ranges from 0.01 to 10 mdarcies. Permeable (1–10 mdarcies) highly hydrate-saturated layers enable depressurization-induced gas production of approximately 20,000 Sm3/D with water of 200 m3/D. Numerical analysis reveals that the dissociation zone expands laterally 25 m at the front after 6 days. Gas rate is expected to increase with time, owing to the expansion of the dissociation zone. It is found that permeable highly hydrate-saturated layers increase the gas–water ratio of the production fluid. The identification of such layers is critically important to increase the en...
419 citations
TL;DR: A large number of cationic, anionic, non-ionic, and amphoteric surfactants have been investigated on a laboratory scale under different conditions of temperature and salinity as mentioned in this paper.
Abstract: Surfactant flooding is an important technique used in enhanced oil recovery to reduce the amount of oil in pore space of matrix rock. Surfactants are injected to mobilize residual oil by lowering the interfacial tension between oil and water and/or by the wettability alteration from oil-wet to water-wet. A large number of cationic, anionic, non-ionic, and amphoteric surfactants have been investigated on a laboratory scale under different conditions of temperature and salinity. Selection of the appropriate surfactant is a challenging task, and surfactants have to be evaluated by a series of screening techniques. Different types of surfactants along with their limitations are reviewed with particular emphasis on the phase behavior, adsorption, interfacial tension, and structure–property relationship. Factors affecting the phase behavior, interfacial tension, and wettability alteration are also discussed. Field applications of surfactants for chemical enhanced oil recovery in carbonate and sandstone reservoi...
392 citations
TL;DR: In this paper, a symmetric supercapacitor with high specific capacitance and high energy density of 7.8 Wh kg-1 was fabricated by a two-step synthesis via carbonization followed by KOH activation of rice straw at 600 °C in an argon atmosphere.
Abstract: Biomass-derived activated carbon materials were prepared by a two-step synthesis via carbonization followed by KOH activation of rice straw at 600 °C in an argon atmosphere. The formation of disordered micro- and mesopores on carbon by KOH chemical activation and the high specific surface area of ∼1007 m2 g–1 were confirmed by N2 adsorption–desorption. Further, the scanning electron microscopic analysis revealed the formation of disordered pores over the carbon surface, and the transmission electron microscopic analysis confirmed the formation and aggregation of ultrafine carbon nanoparticles of ∼5 nm in size after the carbonization and activation processes. The three-electrode cell in aqueous electrolyte shows high specific capacitance of 332 F g–1, with high specific capacitance retention of 99% after 5000 cycles. The fabricated symmetric supercapacitor device in aqueous 1 M H2SO4 electrolyte showed a high specific capacitance of 156 F g–1, with a high energy density of 7.8 Wh kg–1. The symmetric device...
277 citations
TL;DR: A review of processes to remove nitrogen from oil emphasizes studies that investigated denitrogenation of industrial feedstocks, such as refinery fractions, heavy oils, and bitumens as mentioned in this paper.
Abstract: The selective removal of nitrogen-containing compounds from oil and oil fractions is of interest because of the potential deleterious impact of such compounds on products and processes. Problems caused by nitrogen-containing compounds include gum formation, acid catalyst inhibition and deactivation, acid–base pair-related corrosion, and metal complexation. A brief overview of the classes of nitrogen compounds found in oil is provided. The review of processes to remove nitrogen from oil emphasizes studies that investigated denitrogenation of industrial feedstocks, such as refinery fractions, heavy oils, and bitumens. The main topics covered are hydrotreating, liquid–liquid phase partitioning, solvent deasphalting, adsorption, chemical conversion followed by separation, and microbial conversion. Chemical conversion processes include oxidative denitrogenation, N-alkylation, complexation with metal salts, and conversion in high-temperature water. There are many processes for denitrogenation by separation of t...
240 citations
TL;DR: In this paper, a technoeconomic analysis was conducted for metal-organic framework (MOF) adsorbents, which are promising candidates for light-duty vehicle on-board natural gas and hydrogen storage.
Abstract: A techno-economic analysis was conducted for metal–organic framework (MOF) adsorbents, which are promising candidates for light-duty vehicle on-board natural gas and hydrogen storage. The goal of this analysis was to understand cost drivers for large-scale (2.5 Mkg/year) MOF synthesis and to identify potential pathways to achieving a production cost of less than $10/(kg of MOF). Four MOFs were analyzed with four different metal centers and three different linkers: Ni2(dobdc) (dobdc4– = 2,5-dioxido-1,4-benzenedicarboxylate; Ni-MOF-74), Mg2(dobdc) (dobdc4– = 2,5-dioxido-1,4-benzenedicarboxylate; Mg-MOF-74), Zn4O(bdc)3 (bdc2– = 1,4-benzenedicarboxylate; MOF-5), and Cu3(btc)2 (btc3– = 1,3,5-benzenetricarboxylate; HKUST-1). Baseline costs are projected to range from $35/kg to $71/kg predicated on organic solvent (solvothermal) syntheses using an engineering scale-up of laboratory-demonstrated synthesis procedures and conditions. Two alternative processes were analyzed to evaluate the cost impact of reducing so...
233 citations
TL;DR: The Iġnik Sikumi Gas Hydrate Exchange Field Experiment was conducted by ConocoPhillips in partnership with the U.S. Geological Survey within the Prudhoe Bay Unit on the Alaska North Slope during 2011 and 2012 as discussed by the authors.
Abstract: The Iġnik Sikumi Gas Hydrate Exchange Field Experiment was conducted by ConocoPhillips in partnership with the U.S. Department of Energy, the Japan Oil, Gas and Metals National Corporation, and the U.S. Geological Survey within the Prudhoe Bay Unit on the Alaska North Slope during 2011 and 2012. The primary goals of the program were to (1) determine the feasibility of gas injection into hydrate-bearing sand reservoirs and (2) observe reservoir response upon subsequent flowback in order to assess the potential for CO2 exchange for CH4 in naturally occurring gas hydrate reservoirs. Initial modeling determined that no feasible means of injection of pure CO2 was likely, given the presence of free water in the reservoir. Laboratory and numerical modeling studies indicated that the injection of a mixture of CO2 and N2 offered the best potential for gas injection and exchange. The test featured the following primary operational phases: (1) injection of a gaseous phase mixture of CO2, N2, and chemical tracers; (2...
224 citations
TL;DR: This article analyzed asphaltene samples by positive-ion atmospheric pressure photoionization Fourier transform ion cyclotron resonance mass spectrometry and performed infrared multiphoton dissociation to identify their aromatic core structures to shed light on the abundance of island and archipelago structural motifs.
Abstract: For decades, discussion of asphaltene structure focused primarily on molecular weight. Now that it is widely accepted that asphaltene monomers are between ∼250 and 1200 g/mol, disagreement has turned to asphaltene architecture. The classic island model depicts asphaltenes as single core aromatic molecules with peripheral alkyl side chains, whereas the less widely accepted archipelago model, includes multiple aromatic cores that are alkyl-bridged with multiple polar functionalities. Here, we analyze asphaltene samples by positive-ion atmospheric pressure photoionization Fourier transform ion cyclotron resonance mass spectrometry and perform infrared multiphoton dissociation to identify their aromatic core structures to shed light on the abundance of island and archipelago structural motifs. Our results indicate that island and archipelago motifs coexist in petroleum asphaltenes, and unlike readily accessible island motifs, asphaltene purification is required to detect and characterize archipelago species b...
221 citations
TL;DR: In this paper, a review of polymer gel systems that can handle high-temperature excessive water treatments is presented and categorized into three major types: in situ cross-linked polymer gels, preformed gels and foamed gels.
Abstract: Polymer gel systems as water management materials have been widely used in recent years for enhanced oil recovery applications. However, most polymer gel systems are limited in their ability to withstand the harsh environments of high temperature and high salinity. Those polymer gel systems that can handle high-temperature excessive water treatments are reviewed in this paper and categorized into three major types: in situ cross-linked polymer gels, preformed gels, and foamed gels. Future directions for the development of polymer gel systems for high-temperature conditions are recommended. For excessive water management with temperatures from 80 to 120 °C, current polymer systems are substantially adequate. Polymer gel systems composed of partially hydrolyzed polyacrylamide (HPAM)/chromium can be combined with nanoparticle technology to elongate their gelation time and reduce the adsorption of chromium ions in the formation. Phenolic resin cross-linker systems have reasonable gelation times and gel streng...
209 citations
TL;DR: In this article, atomic force microscopy (AFM) data of individual molecules provide information about the molecular geometry, aromaticity, the content of nonhexagonal rings, typical types and locations of heterocycles, occurrence, length and connectivity of alkyl side chains, and ratio of archipelago- vs island-type architectures.
Abstract: Heavy oil molecular mixtures were investigated on the basis of single molecules resolved by atomic force microscopy. The eight different samples analyzed include asphaltenes and other heavy oil fractions of different geographic/geologic origin and processing steps applied. The collected AFM data of individual molecules provide information about the molecular geometry, aromaticity, the content of nonhexagonal rings, typical types and locations of heterocycles, occurrence, length and connectivity of alkyl side chains, and ratio of archipelago- vs island-type architectures. Common and distinguishing structural motifs for the different samples could be identified. The measured size distributions and the degree of unsaturation by scanning probe microscopy is consistent with mass spectrometry data presented herein. The results obtained reveal the complexity, properties and specifics of heavy oil fractions with implications for upstream oil production and downstream oil processing. Moreover, the identified molec...
194 citations
TL;DR: A review of pyrolysis technologies, focusing on reactor designs and companies commercializing these technologies, is provided in this paper, where the authors present slow, intermediate, fast, and microwave technologies that share commonalities in their designs.
Abstract: This paper provides a review of pyrolysis technologies, focusing on reactor designs and companies commercializing these technologies. The renewed interest in pyrolysis is driven by the potential to convert lignocellulosic materials into bio-oil and biochar and the use of these intermediates for the production of biofuels, biochemicals, and engineered biochars for environmental services. This review presents slow, intermediate, fast, and microwave pyrolysis as complementary technologies that share some commonalities in their designs. While slow pyrolysis technologies (traditional carbonization kilns) use wood trunks to produce char chunks for cooking, fast pyrolysis systems process small particles to maximize bio-oil yield. The realization of the environmental issues associated with the use of carbonization technologies and the technical difficulties of operating fast pyrolysis reactors using sand as the heating medium and large volumes of carrier gas, as well as the problems with refining the resulting hi...
193 citations
TL;DR: In this paper, the authors report classical atomistic molecular dynamics simulations of four structurally diverse model asphaltenes, a model resin and their respective mixtures in toluene or heptane under ambient conditions.
Abstract: We report classical atomistic molecular dynamics simulations of four structurally diverse model asphaltenes, a model resin, and their respective mixtures in toluene or heptane under ambient conditions. Relatively large systems (∼50 000 atoms) and long time scales (>80 ns) are explored. Wherever possible, comparisons are made to available experimental observations asserting the validity of the models. When the asphaltenes are dissolved in toluene, a continuous distribution of cluster sizes is observed with average aggregation number ranging between 3.6 and 5.6, monomers and dimers being the predominant species. As expected for mixtures in heptane, the asphaltene molecules tend to aggregate to form a segregated phase. There is no evidence of the distinct formation of nanoaggregates, and the distribution of clusters is found to be continuous in character. Analysis of the shape of the clusters of asphaltenes suggests that they are generally spherical in character, with the archipelago models favoring longer p...
TL;DR: In this paper, the effect of brine composition and temperature on carbonate wettability was probed by monitoring contact angle change of sessile oil droplets upon switching from high salinity to lower salinity brines.
Abstract: It has been proposed that increased oil recovery in carbonates by modification of ionic composition or altering salinity occurs mainly at a temperature exceeding 70–80 °C. The argument was that elevated temperatures enhance adsorption of the potential determining ions which then modifies wettability to a less-oil-wetting state. According to this rationale, it becomes questionable if diluted brines or brines without these ions can be still applicable. Therefore, the aim of this paper is to investigate if the wettability alteration truly depends on temperature and if so how the trend with temperature can be explained. We followed a combined experimental and theoretical modeling approach. The effect of brine composition and temperature on carbonate wettability was probed by monitoring contact angle change of sessile oil droplets upon switching from high salinity to lower salinity brines. IFT measurements as a function of salinity and temperature along with extensive ζ-potential measurements as a function of ...
TL;DR: A review of the literature has revealed that current coalbed methane development in China faces several technical challenges as discussed by the authors, including low permeability, subhydrostatic reservoir pressure, and a lack of understanding of the connectivity of coal seams.
Abstract: Coalbed methane (CBM) resources in China have been estimated to exceed 36 Tcm. As of 2014, there were ∼9300 producing CBM wells in China with an annual production of ∼4.4 Bcm. To satisfy its need for energy and to transition to a low-carbon economy, China has a big need to accelerate CBM development. This paper gives an overview of the status of CBM development in China, identifies key technical challenges, and proposes solutions to overcome them. Our review of the literature has revealed that current CBM development in China faces several technical challenges. Current projects are focused on high-rank coals in the Qinshui and Ordos basins, which have major geological and engineering challenges. The former includes low permeability, subhydrostatic reservoir pressure, and a lack of understanding of the connectivity of coal seams, which leads to difficulty in sweet spot indication. The latter includes difficulty in hydraulic fracturing in vertical wells, because of the ductile nature of the coal seams in th...
TL;DR: The use of surfactants, such as sodium dodecyl sulfate (SDS), has been shown to increase the surface area available for gas hydrate formation as discussed by the authors.
Abstract: Over the course of the last 50 years, gas hydrates have been proposed for use in a diverse range of applications, including gas storage, gas transportation, gas separation, ice cream production, and seawater desalination. While there have been many studies that have demonstrated the thermodynamic potential for using gas hydrates in these applications, the slow kinetics of formation and, to a lesser extent, dissociation, have hindered their adoption. Since the early 1990s, there have been numerous studies that have highlighted the use of surfactants, such as sodium dodecyl sulfate (SDS), for the enhancement of gas hydrate kinetics. More recently, there has been growing interest in non-surfactant-based methods for enhancing the rate of gas hydrate formation, which physically increase the surface area available for gas hydrate formation. These methods, which include hydrate formation in sand packs, silica gels, dry water, foams, nanoparticles, and hydrogels are relatively recent advances and are discussed in...
TL;DR: In this paper, the pore-throat texture in shale before and after acid-etching has been studied, and the authors found that the roughness of the fracture plane perpendicular to the bedding plane is higher than the roughs of that paralleled to the ground plane, and that the coarseness in both fracture planes perpendicular to and paralleled by the bedsding plane increases as the carbonate minerals content increases.
Abstract: Hydraulic fracturing by stimulated reservoir volume (SRV) is a necessity to realize commercial development of shale gas, and its stimulation mechanism still needs further study, and the effectiveness of supplementary stimulation measures needs further exploration. The shale always contains some carbonate minerals. This paper tests the permeability of acid-etched fracture in shale to explore the influence of carbonate mineral content, acid fluid types and concentration, fracture plane roughness, proppant, and confining pressure on the acid-etched effects in shale, and uses CT scanning to conduct research on variation of microscopic pore-throat texture in shale before and after acid-etching. The test shows that the roughness of the fracture plane perpendicular to the bedding plane is higher than the roughness of that paralleled to the bedding plane, and the roughness in both fracture planes perpendicular to and paralleled to the bedding plane increases as the carbonate minerals content increases. In same gr...
TL;DR: In this paper, the authors assess the ability of anionic surfactant and a mixture of the surfactants and nanoparticles to produce foam for gas mobility control and the enhancement of oil recovery.
Abstract: Foam generation is one of the most promising techniques to overcome gas mobility challenges and improve the sweep efficiency of reservoir fluids. The synergistic effect of surfactant and nanoparticles can help produce a stronger and more stable foam in reservoir porous media. The objective of this work is to assess the ability of anionic surfactant and a mixture of the surfactant and nanoparticles to produce foam for gas mobility control and the enhancement of oil recovery. Static, dynamic, and core flood tests were conducted to evaluate foam strength. Static foam tests in the presence of crude oil showed a clear trend on foam behavior when solid nanoparticles were added to surfactant. As the concentration of nanoparticles increases, the foam half-life increases, too. Foamability tests in Bentheimer sandstone showed better foam generation and stabilization when nanoparticles were used. The addition of nanoaprticles to surfactant solutions resulted in higher pressure drop and, therefore, higher reduction o...
TL;DR: A soft sensor system based on deep learning is proposed to predict the outlet oxygen content online and a multilayer deep belief network (DBN) is designed to extract the nonlinear features for a better description of the important trends in a combustion process.
Abstract: As an increasingly popular method in the machine learning field, deep learning is applied to industrial combustion processes in this work. Using easily available color flame images obtained by the charge-coupled device (CCD), a soft sensor system based on deep learning is proposed to predict the outlet oxygen content online. Unlike the traditional principal component analysis which only extracts linear features, a multilayer deep belief network (DBN) is designed to extract the nonlinear features for a better description of the important trends in a combustion process. With the DBN-based multilevel representation of the CCD flame images, more useful information about the physical properties of a flame can be characterized. Sequentially, in a supervised fine-tuning stage, two DBN-based regression models are simply constructed to obtain the nonlinear relationship between the flame images and the outlet oxygen content. The advantages of the proposed deep learning-based analyzing and modeling method are demons...
TL;DR: In this article, the authors revisited available absolute and Gibbs excess adsorption models for describing methane in shales, and compared the efficacy of each model in describing both high pressure and low pressure methane adsorbing isotherms.
Abstract: Finding an optimized adsorption model to estimate the true adsorbed quantity of methane in shale at reservoir conditions is fundamental for estimating the gas-in-place (GIP), and developing an accurate shale gas transport model. However, describing true methane adsorption behavior in shale is challenging because the density or volume of the adsorbed phase cannot be measured directly using current technology. There are several models available to describe the observed adsorption isotherms and extrapolate the true adsorbed quantity of methane, but a consensus model has not been reached by researchers. This work first revisits available absolute and Gibbs excess adsorption models for describing methane in shales. It then compares nine available adsorption models to assess the efficacy of each model in describing both high pressure and low pressure methane adsorption isotherms in shales. Three aspects of the adsorption model are compared: (1) the goodness-of-fit of each adsorption model, (2) interpretation of...
TL;DR: In this paper, a series of porous carbons for CO2 capture were developed by simple carbonization and KOH activation of coconut shells under very mild conditions, and the porous carbon prepared at a KOH/precursor ratio of 3 and 600 °C exhibits an enhanced CO2 adsorption capacity of 4.23 and 6.04 mmol/g at 25 and 0 °C under 1 bar, respectively.
Abstract: A series of porous carbons for CO2 capture were developed by simple carbonization and KOH activation of coconut shells under very mild conditions. Different techniques such as nitrogen sorption, X-ray diffraction, scanning emission microscopy, and transmission electron microscopy were used to characterize these sorbents. Owing to the high amount of narrow micropores within the carbon framework, the porous carbon prepared at a KOH/precursor ratio of 3 and 600 °C exhibits an enhanced CO2 adsorption capacity of 4.23 and 6.04 mmol/g at 25 and 0 °C under 1 bar, respectively. In addition to the high CO2 uptake, these samples also show fast adsorption kinetics, moderate heat of adsorption, high CO2 over N2 selectivity, excellent recyclability and stability, and superior dynamic CO2 capture capacity. The application of coconut shell as precursors for porous carbons provides a cost-effective way for the development of better adsorbents for CO2 capture.
TL;DR: In this article, the in situ modification of positively charged AlOOH nanoparticles via the adsorption of the anionic surfactant sodium dodecyl sulfate (SDS) and the characterization of foam stabilized by Al-OHA nanoparticles in synergy with SDS under different conditions were studied.
Abstract: Foams have been widely used in oilfields for effective profile control and displacement. However, foams stabilized by surfactants lack long-term stability, especially in an oil reservoir. Here, we have studied the in situ modification of positively charged AlOOH nanoparticles via the adsorption of the anionic surfactant sodium dodecyl sulfate (SDS) and the characterization of foam stabilized by AlOOH nanoparticles in synergy with SDS under different conditions. Changes in the zeta potential and adsorption isotherm of the AlOOH nanoparticles confirmed their modification. The most stable foam was obtained with an SDS/AlOOH concentration ratio of 5:1; further increases of the SDS concentration led to a decrease and subsequent increase in foam stability. The relationships between the zeta potential, three-phase contact angle, nanoparticle aggregate size, and foam stability were comprehensively analyzed, revealing that foam stability was affected by all of these factors. We concluded that nanoparticles with pa...
TL;DR: In this article, comparative studies with PAM and TVP, having more similar molecular weights, were performed with regard to their rheological behaviors, thermal stability, and core flooding feasibility.
Abstract: High-molecular-weight polyacrylamide (PAM) has been widely used in chemically enhanced oil recovery (EOR) processes under mild conditions, but its poor tolerance to high temperature and high salinity impeded the use in severe oil reservoirs. To overcome the inadequacies of PAM, thermoviscosifying polymers (TVPs) whose viscosity increases upon increasing temperature and salinity were developed in recent years. In this work, comparative studies with PAM and TVP, having more similar molecular weights, were performed with regard to their rheological behaviors, thermal stability, and core flooding feasibility. It was found that the TVP aqueous solution exhibited thermothickening ability, even at a polymer concentration of 0.2 wt % with a total dissolved solids ratio (TDS) of 101 000 mg L–1 upon increasing temperature, while PAM only showed a monotonic decrease in viscosity under identical conditions. Remaining viscosity of TVP was higher than that of PAM after aging at 45 or 85 °C for one month. Core flooding ...
TL;DR: In this article, a review of recent research and development work on CLC using gaseous fuels, including a technological and economic assessment, types of oxygen carriers (OCs), reactor types, coke formation and OCs poisoning, efficiency and exergy analys...
Abstract: The world-wide consumption of natural gas (NG) and other fossil fuels (e.g., coal and crude oil) is ever increasing. However, most CO2 resulting from either NG combustion or other processes is released into the atmosphere without capture. Chemical looping combustion (CLC) is a two-step combustion technology for power and heat generation with inherent CO2 capture, using either gaseous fuels or solid and liquid fuels. A previous review focused on CLC of solid fuels or CLC of all types of fuels but did not give an in-depth and specific discussion of gaseous fuel CLC systems. China is one of the largest consumers of NG, coal, and crude oil in the world, and it is essential to develop an alternative technology to take the place of gaseous fuel (e.g., NG) combustion. This Review summarizes recent research and development work on CLC using gaseous fuels, including a technological and economic assessment, types of oxygen carriers (OCs), reactor types, coke formation and OCs poisoning, efficiency and exergy analys...
TL;DR: In this article, a comprehensive review of low-salinity water injection as an EOR method is presented, with a specific focus on consistencies or lack of them, that occurs primarily due to inadequate understanding of oil-brine and rock-oil -brine interactions.
Abstract: Low-salinity water flooding (LSWF) is an emerging and inexpensive enhanced oil recovery (EOR) method. The technique hinges on the following concept: as salinity of injected water reduces, additional oil is recovered. However, LSWF remains emerging because its underlying mechanisms have been largely elusive, and the identified ones have been controversial. If properly investigated, smart water injection may contribute to harnessing both heavy-oil reservoirs, which account for nearly 80% of world’s petroleum reserves, and conventional light-to-medium oil reservoirs. This report presents a comprehensive review of low-salinity water injection as an EOR method, with a specific focus on consistencies or lack of them, that occurs primarily due to inadequate understanding of oil–brine and rock–oil–brine interactions. In presenting well-documented scientific information, we expect to apprise industry and academic researchers that LSWF warrants more-advanced research based on interdisciplinary approach (bridging th...
TL;DR: In this paper, an ultralow-emission coal-fired power plant, the emission concentrations of condensable and filterable particulate matter in the stack were 1.6 mg/nm3 and 7.9 mg/Nm3, respectively.
Abstract: Condensable particulate matter is the predominant contributor to the total particulate matter emissions of coal-fired power plants. In the studied ultralow-emission coal-fired power plant, the emission concentrations of condensable and filterable particulate matter in the stack were 1.6 mg/Nm3 and 7.9 mg/Nm3. The organic fraction in condensable particulate matter was mainly composed of alkanes, esters, and other complex organic compounds. The organic fraction comprised 54% of the total concentrations of condensable particulate matter tested at the stack. The organic fraction in condensable particulate matter might contribute significantly to the organic carbon in atmospheric PM2.5. SO42– accounted for the highest concentrations in the inorganic fraction of condensable particulate matter. Na and Ca were predominant metal elements in the inorganic fraction. The inorganic fraction of condensable particulate matter mainly contributed to the water-soluble ions in atmospheric PM2.5. The total particulate matter...
TL;DR: In this article, the potential impacts of shale iron chemistry on hydraulic stimulation were investigated and the extent to which such reactions occur and their rates, mineral products, and physical locations within shale pore spaces are unknown.
Abstract: Hydraulic fracturing of unconventional hydrocarbon reservoirs is critical to the United States energy portfolio; however, hydrocarbon production from newly fractured wells generally declines rapidly over the initial months of production. One possible reason for this decrease, especially over time scales of several months, is the mineralization and clogging of microfracture networks and pores proximal to propped fractures. One important but relatively unexplored class of reactions that could contribute to these problems is oxidation of Fe(II) derived from Fe(II)-bearing phases (primarily pyrite, siderite, and Fe(II) bound directly to organic matter) by the oxic fracture fluid and subsequent precipitation of Fe(III)-(oxy)hydroxides. The extent to which such reactions occur and their rates, mineral products, and physical locations within shale pore spaces are unknown. To develop a foundational understanding of potential impacts of shale iron chemistry on hydraulic stimulation, we reacted sand-sized (150–250 ...
TL;DR: In this paper, the authors provide unexpected experimental evidence of heavy and extra-heavy crude oils viscosity reduction resulting from the presence of nanoparticles (NPs) of different chemical natures (SiO2, Fe3O4, and Al2O3), particle size, surface acidity, and concentration at low-volume fractions.
Abstract: Heavy and extra-heavy oils generally exhibit high viscosity, which is detrimental to their production, transport, and refining. The oil and gas industry has thoroughly investigated the use of chemical agents to improve the mobility of this type of low-quality crude oil at the surface as well as reservoir conditions for many years. In this sense, the main objective of this paper is to provide unexpected experimental evidence of heavy oil and extra-heavy crude oils viscosity reduction resulting from the presence of nanoparticles (NPs) of different chemical natures (SiO2, Fe3O4, and Al2O3), particle size, surface acidity, and concentration at low-volume fractions. The viscosity of the enhanced fluids was measured using a rotational rheometer at shear rates varying between 1 and 75 s–1. Upon addition of nanoparticles, viscosity reduction was observed in all cases evaluated. However, the maximum viscosity reduction of roughly 52% was obtained at a concentration of 1000 mg/L with 7 nm SiO2 nanoparticles at shea...
TL;DR: In this article, Extended-SARA (E-Sara) is proposed as a concept of asphaltene fractionation according to their interfacial activities and adsorption characteristics, providing critical information to correlate specific functional groups with certain characteristics of aggregation, precipitation, and adorption.
Abstract: SARA fractionation separates crude oil into fractions of saturates (S), aromatics (A), resins (R), and asphaltenes (A) based on the differences in their polarizability and polarity. Defined as a solubility class, asphaltenes are normally considered as a nuisance in the petroleum industry mainly as a result of their problematic precipitation and adsorption at oil–water and oil–solid interfaces. Because a broad range of molecules fall within the group of asphaltenes with distinct sizes and structures, considering the asphaltenes as a whole was noted to limit the deep understanding of governing mechanisms in asphaltene-induced problems. Extended-SARA (E-SARA) is proposed as a concept of asphaltene fractionation according to their interfacial activities and adsorption characteristics, providing critical information to correlate specific functional groups with certain characteristics of asphaltene aggregation, precipitation, and adsorption. Such knowledge is essential to addressing asphaltene-related problems ...
TL;DR: In this paper, the authors argue that the hydrophobic effect plays a critical role in gas hydrate formation, and that a dissolved hydrophobe organizes the surrounding water into a clathrate-like structure.
Abstract: Additives such as surfactants, polymers, salts, and hydrophobic particles are well-known (and used) to influence gas hydrate formation (GHF). This paper reviews and discusses the mechanisms of their effects. The effects of additives on GHF appear to vary greatly from one additive to another. Even a given additive can change from a promoter to an inhibitor and vice versa when the working conditions are changed. The available literature cannot explain the diverse effects of additives. We argue that the hydrophobic effect plays a critical role in gas hydrate formation. A dissolved hydrophobe organizes the surrounding water into a clathrate-like structure and thereby promotes hydrate formation. A hydrophile, however, disrupts the surrounding water structure and inhibits hydrate formation. Moreover, cooperative hydrophobic interactions create an increased gas concentration around a hydrophobe, which also favors the hydrate formation. In contrast, a hydrophile competes with the gas for water and thereby hinders...
TL;DR: In this paper, the authors investigated the effect of cold finger and flow loop on the wax deposition and the performance of wax inhibitors under the same initial temperature difference and comparable shear stress conditions.
Abstract: Chemical inhibition is one of the methods to mitigate deposition of wax in pipelines; however, the efficiency of the inhibitors needs to be validated in the laboratory prior to field applications. Cold finger, as the most commonly used experimental setup in the field, has quite a different shear regime and temperature field compared to the flow loop and field production pipeline. This paper investigates the flow field (cold finger and flow loop) effect on the wax deposition and the performance of wax inhibitors under the same initial temperature difference and comparable shear stress conditions. The normalized deposit mass, wax content, carbon number distribution, and wax mass flux were investigated in these two different flow fields, and the performance of wax inhibitors was also investigated. Moreover, the results from this study are expected to serve as a basis for selecting proper inhibitors for field applications based on laboratory testing.
TL;DR: In this article, high-pressure methane sorption isotherms were collected on selected Paleozoic shales from the Sichuan Basin from the Guggenheim-Anderson-de Boer (GAB) model.
Abstract: High-pressure methane sorption isotherms were collected on selected Paleozoic shales from the Sichuan Basin. Excess sorption measurements were performed on shales with varied water content (dry, moisture equilibrated at 33%, 53%, 75%, and 97% relative humidities) at 39 °C and up to 25 MPa. Water uptake isotherms were collected at 24 °C and parametrized by the Guggenheim–Anderson–de Boer (GAB) model. The effect of organic richness, mineral compositions, and pore structure characteristics on water uptake and methane sorption behavior has been investigated. The mechanism responsible for the decrease in methane sorption capacity of moisture-equilibrated shales is discussed. Water uptake of shales is primarily controlled by clay minerals, and shows a positive correlation with clay mineral content. Water sorption isotherms of shales can be approximately expressed as the sum of the isotherms of individual clay minerals on a mass-fraction base. Methane sorption capacity of these shales is controlled by TOC conten...