Showing papers by "China University of Petroleum published in 2008"
TL;DR: In this paper, a series of servo-controlled triaxial fracturing experiments were conducted to study hydraulic fracture propagation behavior and fracture geometry in naturally fractured reservoirs through three interaction types between induced fractures with pre-fracture were observed.
416 citations
TL;DR: In this article, the authors investigated the effect of thermochemical sulfate reduction (TSR) on the isotope compositions of different hydrocarbon gas components at different TSR stages.
Abstract: The Puguang gas field is the largest gas field found in marine carbonates in China. Marine carbonate reservoirs in this field were buried to a depth of about 7000 m (22,966 ft) and experienced maximum temperature up to 220C before uplift to the present-day depth of 5000–5500 m (16,404–18,045 ft), with present-day thermal maturity between 2.0 and 3.0% equivalent vitrinite reflectance (Ro). Sulfur-rich pyrobitumens with reflectance up to 3.5% are widespread in the reservoirs and resulted from thermal cracking of crude oils most likely generated from Upper Permian source rocks and thermochemical sulfate reduction (TSR). Natural gases in the Puguang gas field have wide variations in nonhydrocarbon gas contents, with H2S contents between 5.1 and 58.3% and CO2 contents between 7.9 and 18.0%. The hydrocarbon gases originated mainly from thermal cracking of accumulated oil but were altered by TSR. Thermochemical sulfate reduction in the study area exerted different effects on the isotope compositions of different hydrocarbon gas components at different TSR stages. The differential increase of 13C values for different gas components reflects transformation from a heavy-hydrocarbon-gas–dominated TSR stage to a methane-dominated TSR stage. This caused a decrease of 13Cmethane13Cethane values and a corresponding conversion from reversed to normal isotope distributions. Thermochemical sulfate reduction in the study area appears to have been limited by sulfate concentrations in the reservoirs. A successive, three-stage TSR series, namely, liquid-hydrocarbon–involved TSR, heavy-hydrocarbon-gas–dominated TSR, and methane-dominated TSR, occurred in reservoirs with sufficient sulfate concentration. Methane can be the dominant organic reactant for TSR, but only at elevated temperature and after most C2+ hydrocarbons are exhausted.
336 citations
TL;DR: In this article, a series of CoOx/nmCeO2-supported cobalt oxide materials with variable Co/Ce atomic ratios were prepared by the method of ultrasonic assisted incipient-wetness impregnation.
Abstract: Nanometric CeO2-supported cobalt oxide materials with variable Co/Ce atomic ratios were prepared by the method of ultrasonic-assisted incipient-wetness impregnation. The catalytic behaviors of a series of CoOx/nmCeO2 catalysts have been studied for soot combustion. XRD, XPS, Raman, UV–vis DRS and FT-IR spectroscopy characterization results indicated that CoO or cobalt–cerium solid solutions were formed in the samples with the low Co loading amount, while Co3O4 was formed in the samples with high Co loading amount. CoOx/nmCeO2 catalysts can further promote soot combustion in contrast to nanometric CeO2. This improvement is related to the increase in the redox properties of the catalysts brought about by loading cobalt oxide on nanometric CeO2. The TPR experiment results under hydrogen atmosphere indicated that the presence of Co decreases the reduction temperature of catalyst from 555 °C (nanometric CeO2) to 286 °C (Co20/nmCeO2). On the other hand, attributing to nanoparticle effect and NO2 formation, Com/nmCeO2 oxide catalysts prepared in this study have very high activity for soot combustion. The best catalytic activity was obtained over Co20/nmCeO2 catalyst that T10, T50, T90 were 286 °C, 368 °C, 418 °C, respectively, and S C O 2 m was 98.8%. Compared with the blank case (i.e., without catalyst) for soot combustion, T50 decreased by more than 200 °C and S C O 2 m increased by 40% point. And this catalytic activity for the combustion of soot particle is as good as supported Pt catalysts, which is the best catalyst system so far reported for soot combustion under loose contact conditions. This temperature of soot combustion can ensure immediate activation of the catalyst on the filter under the conditions of diesel engine emissions.
254 citations
TL;DR: In this article, carboxylic and ester functionalized multi-walled carbon nanotube (MWCNT)/poly(vinylidene fluoride) composites were fabricated by evaporating suspensions of the nanotubes in PVDF.
239 citations
TL;DR: Mesoporous nanocrystalline zirconia with high surface area and pure tetragonal crystalline phase has been prepared by the surfactant-assisted route, using Pluronic P123 block copolymer surfactants as discussed by the authors.
Abstract: Mesoporous nanocrystalline zirconia with high-surface area and pure tetragonal crystalline phase has been prepared by the surfactant-assisted route, using Pluronic P123 block copolymer surfactant. The synthesized zirconia showed a surface area of 174 m2 g−1 after calcination at 700 °C for 4 h. The prepared zirconia was employed as a support for nickel catalysts in dry reforming reaction. It was found that these catalysts possessed a mesoporous structure and even high-surface area. The activity results indicated that the nickel catalyst showed stable activity for syngas production with a decrease of about 4% in methane conversion after 50 h of reaction. Addition of promoters (CeO2, La2O3 and K2O) to the catalyst improved both the activity and stability of the nickel catalyst, without any decrease in methane conversion after 50 h of reaction.
201 citations
TL;DR: In this paper, a novel synthesis and selective bioseparation of the composite of Fe3O4 magnetic nanocrystals and highly ordered MCM-41 type periodic mesoporous silica nanospheres was reported.
Abstract: In this paper, we report a novel synthesis and selective bioseparation of the composite of Fe3O4 magnetic nanocrystals and highly ordered MCM-41 type periodic mesoporous silica nanospheres. Monodisperse superparamagnetic Fe3O4 nanocrystals were synthesized by thermal decomposition of iron stearate in diol in an autoclave at low temperature. The synthesized nanocrystals were encapsulated in mesoporous silica nanospheres through the packing and self-assembly of composite nanocrystal-surfactant micelles and surfactant/silica complex. Different from previous studies, the produced magnetic silica nanospheres (MSNs) possess not only uniform nanosize (90 similar to 140 nm) but also a highly ordered mesostructure. More importantly, the pore size and the saturation magnetization values can be controlled by using different alkyltrimethylammonium bromide surfactants and changing the amount of Fe3O4 magnetic nanocrystals encapsulated, respectively. Binary adsorption and desorption of proteins cytochrome c (cyt c) and bovine serum albumin (BSA) demonstrate that MSNs are an effective and highly selective adsorbent for proteins with different molecular sizes. Small particle size, high surface area, narrow pore size distribution, and straight pores of MSNs are responsible for the high selective adsorption capacity and fast adsorption rates. High magnetization values and superparamagnetic property of MSNs provide a convenient means to remove nanoparticles from solution and make the re-dispersion in solution quick following the withdrawal of an external magnetic field.
177 citations
TL;DR: XPS analysis showed that Fe3+ was not on the surface of TiO2 nanoparticles, but inserting into the matrix interior, and the photoactivity degradation of MB on Fe-doped TiO 2 nanoparticles decreased.
173 citations
TL;DR: In this article, a novel Pd/BiVO4 visible light driven composite photocatalysts were synthesized by the impregnation method, which were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), XPS, and UV-vis diffuse reflectance spectra (DRS).
166 citations
TL;DR: In this paper, the Lagrange approach was used to simulate the solids concentrations of different size particles in a scroll cyclone separator using the platform of commercial CFD software package, FLUENT 6.1.
152 citations
TL;DR: The spatial distribution of putative soil-related AOA in certain sampling stations indicated a strong impact of the Changjiang freshwater discharge on the marine benthic microbial ecosystem.
Abstract: Ammonia-oxidizing archaea (AOA) have recently been found to be potentially important in nitrogen cycling in a variety of environments, such as terrestrial soils, wastewater treatment reactors, marine waters and sediments, and especially in estuaries, where high input of anthropogenic nitrogen is often experienced. The sedimentary AOA diversity, community structure and spatial distribution in the Changjiang Estuary and the adjacent East China Sea were studied. Multivariate statistical analysis indicated that the archaeal amoA genotype communities could be clustered according to sampling transects, and the station located in an estuarine mixing zone harboured a distinct AOA community. The distribution of AOA communities correlated significantly with the gradients of surface-water salinity and sediment sorting coefficient. The spatial distribution of putative soil-related AOA in certain sampling stations indicated a strong impact of the Changjiang freshwater discharge on the marine benthic microbial ecosystem. Besides freshwater, nutrients, organic matter and suspended particles, the Changjiang Diluted Water might also contribute to the transport of terrestrial archaea into the seawater and sediments along its flow path.
148 citations
TL;DR: In this article, a simple and effective route to prepare zinc oxide nanoparticle with higher photocatalytic activity through depositing zinc oxide on the silica particle surface, moreover, the catalyst is easier to recover due to its higher density.
TL;DR: In this paper, a series of HZSM-5 zeolites modified by different amounts of phosphorus (P/HZSM5) were prepared, and physicochemical features of P-modified catalysts were characterized by means of XRD, BET, NH 3 TPD, FT-IR spectra of adsorbed pyridine, etc., and their performances for the catalytic cracking of the mixed C 4 alkanes to produce light olefins were investigated.
Abstract: A series of HZSM-5 zeolites modified by different amounts of phosphorus (P/HZSM-5) were prepared. The physicochemical features of P/HZSM-5 catalysts were characterized by means of XRD, BET, NH 3 -TPD, FT-IR spectra of adsorbed pyridine, etc., and their performances for the catalytic cracking of the mixed C 4 alkanes to produce light olefins were investigated. The results indicated that phosphorus (P) modification not only modulated the amount of acidic sites and the percentage of weak acidic sites in total acidic sites, but also regulated the acid type, i.e., the ratio of L/B (Lewis acid/Bronsted acid). The introduction of P also altered the basic characteristics of HZSM-5 which was evidenced by CO 2 -TPD analysis. Consequently, P modification with suitable amount was favorable for enhancing the selectivity to light olefins, especially to propene. At the temperature of 650 °C, the maximum yields of propene and ethene were achieved 25.6 and 33.9%, which were higher than those over parent HZSM-5 by 7 and 4.5%, respectively. Aromatics yield was found to be decreased with the increasing P loading due to the reduction of strong acid and the formation of new basic site which inhibited the hydrogen transfer reaction. All this indicates that P-modified HZSM-5 zeolites are effective catalysts for the cracking of mixed C 4 alkanes to produce more light olefins.
TL;DR: In this article, the authors discuss the recent achievements in design and synthesis of new functional molecules towards information processing at the molecular level and high-density information storage, focusing on nanometer-scale electrical recording based on the conductance transition of organic molecules, and multimode data storage on multiresponsive molecules.
Abstract: In this Progress Report, we discuss our recent achievements in design and synthesis of new functional molecules towards information processing at the molecular level and high-density information storage. These include: 1) new molecular switches, logic gates, and combinational logic circuits based on molecules and ensembles with photochromic spiropyran units that undergo reversible structural transformation among multistates, in response to external inputs such as light, protons, and metal ions; 2) high-density information storage, mainly focusing on nanometer-scale electrical recording based on the conductance transition of organic molecules, and multimode data storage on multiresponsive molecules. Relevant progress and an outlook in this area are also discussed.
TL;DR: It is proved that the bounded real lemma for discrete singular system can be described by a strict matrix inequality, which will lead to more tractable and reliable computation when applying them to design control systems.
TL;DR: A series of TiO 2 /ACF samples were prepared by sol-gel-adsorption method and were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) and nitrogen adsorption.
TL;DR: In this paper, a double-work-point control strategy was proposed to improve the performance of a hybrid hydraulic excavator by controlling the working points of the engine and the capacitor.
TL;DR: In this article, the nanometric Ln-Na-Cu-O (Ln = La, Pr, Nd, Sm, Gd) perovskite-like complex oxide catalysts were prepared by using citric acid as a ligand and an adjusting agent of particle-size and morphology.
Abstract: The nanometric Ln-Na-Cu-O (Ln = La, Pr, Nd, Sm, Gd) perovskite-like complex oxide catalysts were prepared by sol–gel auto-combustion method using citric acid as a ligand and an adjusting agent of particle-size and morphology. Their structures and physico-chemical properties were examined by chemical analysis, XRD, SEM, FT-IR, H2-TPR and MS-NO-TPD. The catalytic performances of these perovskite-like oxides for the simultaneous removal of soot and NOx were investigated by a technique of the temperature-programmed reaction (TPR). In the Ln-Na-Cu-O catalysts, the partial substitution of Na for La at A-site led to the formation of Cu3+ and/or oxygen vacancy, thus the catalytic activity was remarkably enhanced. The optimal substitution amount of Na (x) is equal to 0.3 for the reduction of NOx, and x is equal to 0.7 for soot combustion. Moreover, attributing to the effects of very small surface particle sizes of the catalysts and the strong oxidizing ability of NO2 which was produced from NO and O2 in the reactant gases on these catalysts, the nanometric Ln-Na-Cu-O perovskite-like oxides exhibit very high catalytic activities for soot combustion even under loose contact conditions between soot and the catalyst.
TL;DR: In this paper, a visible-light-induced Pt/BiVO 4 composite photocatalyst has been synthesized by the impregnation method, where the Pt element is present as PtCl 4 and disperses in the composite samples.
Abstract: Visible-light-induced Pt/BiVO 4 composite photocatalyst has been synthesized by the impregnation method. The composition, crystallinity and photo-absorption of the as-prepared samples were characterized by powder X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and UV–vis diffused reflectance spectroscopy. The results indicate that the visible light absorption of the Pt/BiVO 4 photocatalyst is greatly enhanced. The Pt element is present as PtCl 4 and disperses in the composite samples. Photocatalytic activities of the Pt/BiVO 4 samples were evaluated by the methyl orange decomposition under visible light irradiation. The results indicate that the photocatalytic efficiency is significantly improved after the Pt species was loaded. On the basis of experimental results, the mechanism of enhanced photocatalytic activity has been discussed.
TL;DR: In this article, the quantitative characteristics of vortex structures and turbulent events in turbulent channel flows with and without drag reduction were investigated experimentally, and it was shown that the drag-reducing CTAC additive reduced both the strength and frequency of turbulent bursts near the wall, and the characteristics were not only dependent on drag reduction level but also on concentration of additive.
TL;DR: Based on the coexisting intact n-alkane series, evident UCM and 25-norhopanes in the oil as well as the bimodal distribution pattern of homogenization temperatures (T h ), ranging from 80 to 100 ǫ c and from 115 to 135 ǒ c, respectively, in fluid inclusions within the reservoir rocks, it was concluded that the oil reservoir has been twice charged during its oil filling history.
TL;DR: In this article, Nafion composite proton exchange membranes are prepared using mesoporous MCM-41 silica nanospheres as inorganic fillers, and the composite membrane containing I wt.% of fillers displays the best cell performance in direct methanol fuel cell tests.
01 Jan 2008
TL;DR: In this article, preformed particle gel (PPG) treatments for in-depth fluid diversion in four injection wells located in the north of Lamadian, Daqing oilfield, China.
Abstract: The paper describes preformed particle gel (PPG) treatments for in-depth fluid diversion in four injection wells located in the north of Lamadian, Daqing oilfield, China. Lamadian is sandstone oilfield with thick net zones. The selected four injectors have 46 connected producers with average water cut of 95.4% before treatment. The paper reports the detailed information for the four well treatments, including well candidate selection criteria, PPG treatment optimization, real-time monitoring result during PPG injection and reservoir performance after treatment. In addition, a discussion is made to analyze why so large amount of large particles can be injected into the reservoir. Large volume of PPG suspension with concentrations of 2,000-2,500 mg/L and particle sizes of 0.06-3.0 mm was injected into each well and it took about 4 months to finish each injection. The injection volume ranges from 11,458 to 17,625 m per well with a total of 56,269 m of PPG suspension (295,680 lbs of dried PPG) for the four wells. During PPG injection, the increase of the wellhead pressure was quite stable and no PPG was produced from adjacent producers. Recorded real-time monitoring Data about injection pressure and rate, PPG particle size change during PPG injection provide invaluable information to analysis the possibility of fracture/channel in the reservoir. The treatments resulted in an oil increase of 34.8 t/d and average water cut decrease of 0.94% within 10 months after treatments. Introduction Excess water production has become a major problem for oilfeld operators as more and more reservoirs mature due to long term of water flooding. Higher levels of water production result in increased levels of corrosion and scale, increased load on fluid-handling facilities, increased environmental concerns, and eventually well shut-in. Consequently, producing zones are often abandoned in an attempt to avoid water contact, even when the intervals still maitain large volumes of remaining hydrocarbons. Controlling water production has become more and more important to the oil industry. Reservoir heterogeneity is the single most important reason for low oil recovery and early excess water production. Most oilfields in China, which were discovered in continental sedimentary basins, are characterized by complex geological conditions and high permeability contrast inside reservoirs. To maintain reservoir pressure, these reservoirs were developed by water flooding from early stage of their development. Many of them have been hydraulically fractured, intentionally or unintentionally, or have been channeled due to mineral dissolution and production during waterflooding (Liu, 2006). Reservoirs with induced fractures or high-permeability channels are quite common in the mature oilfields. Gel treatment is a cost-effective method to improve sweep efficiency in reservoirs and to reduce excess water production during oil and gas production. Traditionally, gels are usually placed near wellbore of production or injection wells to correct inter-layer heterogeneity or heal fracture. However, the remaining oil on the top of a thick heterogeneous layer has become the most important target to improve oil recovery as a reservoir matures. In-depth diversion gels (Seright, 2004, Frampton, 2004, Sydansk, 2004, 2005, Cheung, 2007, Rousseau, 2005, Bai, 2007) have been reported to penetrate deeply into higher permeability zones or fractures and seal or partially seal them off thus creating high flow resistance in former, watered-out, high permeability portion of the zones. When successful, these gel systems divert a portion of the injection water into areas not previously swept by water shown in Fig. 1. Traditionally in-situ gels have been widely used to control conformance. The mixture of polymer and crosslinker called gelant is injected into target formation and react to form gel to fully or partially seal the formation at reservoir temperature (Sydansk, 1992, Jain, 2005). So the gelation occurs in reservoir conditions. A new trend in gel treatments is applying preformed gels for the purpose because the preformed gels are formed at surface facilities before injection and no gelation occurs in reservoirs so they can overcome some distinct drawbacks inherent in in-situ gelation systems, such as lack of
TL;DR: In this article, a two-stage riser fluid catalytic cracking (TSRFCC) unit was used to transform oils and fats as FCC feed for single or co-feeding with vacuum gas oil (VGO).
TL;DR: In this article, the influence of chemical functionalization on the interfacial bonding characteristics of single-walled nanotubes reinforced polymer composites was investigated using molecular mechanics and molecular dynamics simulations.
TL;DR: In this paper, Dongying and Liaohe diesel fuels with [BF4]−-based ionic liquids were systematically investigated, and the results showed that the absorption capacity of an ionic liquid for the S-compounds in diesel fuels relies on its structure and its size.
TL;DR: The chemically purified multiwalled carbon nanotube/poly(vinylidene fluoride) (MWCNT/PVDF) composites were fabricated in this paper.
TL;DR: In this article, a one-step synthetic pathway that controls both functionality and morphology of functionalized periodic helical mesostructured silicas by the co-condensation of tetraethoxysilane and hydrophobic organoalkoxyselane using achiral surfactants as templates is reported.
Abstract: In this paper a novel one-step synthetic pathway that controls both functionality and morphology of functionalized periodic helical mesostructured silicas by the co-condensation of tetraethoxysilane and hydrophobic organoalkoxysilane using achiral surfactants as templates is reported. In contrast to previous methods, the hydrophobic interaction between hydrophobic functional groups and the surfactant as well as the intercalation of hydrophobic groups into the micelles are proposed to lead to the formation of helical mesostructures. This study demonstrates that hydrophobic interaction and intercalation can promote the production of long cylindrical micelles, and that the formation of helical rod-like morphology is attributed to the spiral transformation from bundles of hexagonally-arrayed and straight rod-like composite micelles due to the reduction in surface free energy. It is also revealed that small amounts of mercaptopropyltrimethoxysilane, vinyltrimethoxysilane, and phenyltrimethoxysilane can cause the formation of helical mesostructures. Furthermore, the helical mesostructured silicas are employed as drug carriers for the release study of the model drug aspirin, and the results show that the drug release rate can be controlled by the morphology and helicity of the materials.
TL;DR: In this article, a composite ionic liquid was used as an acid catalyst for the liquid phase alkylation of isobutane and 2-butene, and the main product obtained was trimethylpentane (>85 ¼ ) and the octane numbers of the alkylates was 98-101.
Abstract: A composite ionic liquid was used as an acid catalyst for the liquid phase alkylation of isobutane and 2-butene. The main product obtained was trimethylpentane (>85 wt.%) and the research octane numbers of the alkylates was 98–101. In the ionic liquid sample, a composite anion [AlCl4CuCl]− was detected by means of ESI-MS. This new species was also confirmed by 27Al NMR and FT-IR characterizations. The effects of anion composition on the product distribution have been investigated. The composite anion plays important roles in improving alkylate quality.
TL;DR: An experimental study of the rhizosphere effect on phytoremediation of petroleum polluted soil was carried out with three species of grasses, namely Pannicum, Eleusine indica (L) Gaerth, and Tall Fescue.
TL;DR: An up-flow biological aerated filter packed with two layers media was employed for tertiary treatment of textile wastewater secondary effluent and it was confirmed that the increase of COD and NH(4)(+)-N removal efficiencies resulted from the increases of DO concentrations, but this variation trend was not observed for TN removal.