Recently, significant oil discoveries have been made in the shallower pay zones of the Jurassic Badaowan Formation (J_(1)b) in the Mahu Sag, Junggar Basin, Northwest China. However, little work has been done on the ge...Recently, significant oil discoveries have been made in the shallower pay zones of the Jurassic Badaowan Formation (J_(1)b) in the Mahu Sag, Junggar Basin, Northwest China. However, little work has been done on the geochemical characteristics and origins of the oil in the J_(1)b reservoir. This study analyzes 44 oil and 14 source rock samples from the area in order to reveal their organic geochemical characteristics and the origins of the oils. The J_(1)b oils are characterized by a low Pr/Ph ratio and high β-carotene and gammacerane indices, which indicate that they were mainly generated from source rocks deposited in a hypersaline environment. The oils are also extremely enhanced in C_(29) regular steranes, possibly derived from halophilic algae. Oil-source correlation shows that the oils were derived from the Lower Permian Fengcheng Formation (P_(1)f) source rocks, which were deposited in a strongly stratified and highly saline water column with a predominance of algal/bacterial input in the organic matter. The source rocks of the Middle Permian lower-Wuerhe Formation (P_(2)w), which were deposited in fresh to slightly saline water conditions with a greater input of terrigenous organic matter, make only a minor contribution to the J_(1)b oils. The reconstruction of the oil accumulation process shows that the J_(1)b oil reservoir may have been twice charged during Late Jurassic–Early Cretaceous and the Paleogene–Neogene, respectively. A large amount volume of hydrocarbons generated in the P_(1)f source rock and leaked from T_(1)b oil reservoirs migrated along faults connecting source beds and shallow-buried secondary faults into Jurassic traps, resulting in large-scale accumulations in J_(1)b. These results are crucial for understanding the petroleum system of the Mahu Sag and will provide valuable guidance for petroleum exploration in the shallower formations in the slope area of the sag.展开更多
Development and production from fractured reservoirs require extensive knowledge about the reservoir structures and in situ stress regimes.For this,this paper investigates fractures and the parameters(aperture and den...Development and production from fractured reservoirs require extensive knowledge about the reservoir structures and in situ stress regimes.For this,this paper investigates fractures and the parameters(aperture and density)through a combination of wellbore data and geomechanical laboratory testing in three separate wells in the Asmari reservoir,Zagros Belt,Iran.The Asmari reservoir(Oligo-Miocene)consists mainly of calcitic and dolomitic rocks in depths of 2000e3000 m.Based on the observation of features in several wellbores,the orientation and magnitude of the in situ stresses along with their influence on reservoir-scale geological structures and neotectonics were determined.The study identifies two regional tectonic fracture settings in the reservoir:one set associated with longitudinal and diagonal wrinkling,and the other related to faulting.The former,which is mainly of open fractures with a large aperture,is dominant and generally oriented in the N45°-90°W direction while the latter is obliquely oriented relative to the bedding and characterized by N45°-90°E.The largest aperture is found in open fractures that are longitudinal and developed in the dolomitic zones within a complex stress regime.Moreover,analysis of drilling-induced fractures(DIFs)and borehole breakouts(BBs)from the image logs revealed that the maximum horizontal stress(SHmax)orientation in these three wells is consistent with the NE-SW regional trend of the SHmax(maximum principal horizontal stress)in the Zagros Belt.Likewise,the stress magnitude obtained from geomechanical testing and poroelastic equations confirmed a variation in stress regime from normal to reverse,which changes in regard to active faults in the study area.Finally,a relationship between the development degree of open fractures and in situ stress regime was found.This means that in areas where the stress regime is complex and reverse,fractures would exhibit higher density,dip angle,and larger apertures.展开更多
There are several advantages to the MIG(Metal Inert Gas)process,which explains its increased use in variouswelding sectors,such as automotive,marine,and construction.A variant of the MIG process,where the sameequipmen...There are several advantages to the MIG(Metal Inert Gas)process,which explains its increased use in variouswelding sectors,such as automotive,marine,and construction.A variant of the MIG process,where the sameequipment is employed except for the deposition of a thin layer of flux before the welding operation,is the AMIG(Activated Metal Inert Gas)technique.This study focuses on investigating the impact of physical properties ofindividual metallic oxide fluxes for 304L stainless steel welding joint morphology and to what extent it can helpdetermine a relationship among weld depth penetration,the aspect ratio,and the input physical properties ofthe oxides.Five types of oxides,TiO_(2),SiO_(2),Fe_(2)O_(3),Cr_(2)O_(3),and Mn_(2)O_(3),are tested on butt joint design withoutpreparation of the edges.A robust algorithm based on the particle swarm optimization(PSO)technique is appliedto optimally tune the models’parameters,such as the quadratic error between the actual outputs(depth and aspectratio),and the error estimated by the models’outputs is minimized.The results showed that the proposed PSOmodel is first and foremost robust against uncertainties in measurement devices and modeling errors,and second,that it is capable of accurately representing and quantifying the weld depth penetration and the weld aspect ratioto the oxides’thermal properties.展开更多
This article examines the dynamics for stochastic plate equations with linear memory in the case of bounded domain. We investigate the existence of solutions and bounded absorbing set by using the uniform pullback att...This article examines the dynamics for stochastic plate equations with linear memory in the case of bounded domain. We investigate the existence of solutions and bounded absorbing set by using the uniform pullback attractors on the tails estimates, and the asymptotic compactness of the random dynamical system is proved by decomposition method, and then we obtain the existence of a random attractor.展开更多
After two well tests in the Asmari well#A, located in the North Dezful zone, it was concluded that in the Jurassic Mus/Alan/Neyriz and Upper Sargelu reservoirs, highly mature colorless oil and gas were trapped, includ...After two well tests in the Asmari well#A, located in the North Dezful zone, it was concluded that in the Jurassic Mus/Alan/Neyriz and Upper Sargelu reservoirs, highly mature colorless oil and gas were trapped, including 4%-6% H2 S. The alternation of Garau shale and the Gotnia anhydrite seal was so efficient that it did not allow the upward migration of petroleum from Jurassic reservoirs to higher levels. Descriptive ratios, chromatograms, pick correlation and cross plots demonstrated that the oil and gas have been derived from a TOC-enriched sequence, consisting of the base of the Garau and the top of the Sargelu Formations. This highly organic matter-rich sequence is traceable as an oil shale in other parts of the North Dezful zone, such as the Gashun section. The petroleum accumulations in both reservoirs are identical, have the same maturity and the same source. Diagrams of δ13 C2 versus δ13 C3, δ13 C1 versus wetness of gas(C1/C2+C3) and δ13 C1 versus δDC1 suggest that the gas is derived from a highly mature source. There are indications of TSR effects on the original petroleum that could have changed the volumetric and isotopic composition of the oil and gas. This result requires more careful study of the petroleum components to be undertaken.展开更多
Sand production from loosely consolidated reservoirs is one of the critical issues in the oil and gas in-dustry all around the world that can cause many problems,such as erosion of surface and well equip-ment,sand acc...Sand production from loosely consolidated reservoirs is one of the critical issues in the oil and gas in-dustry all around the world that can cause many problems,such as erosion of surface and well equip-ment,sand accumulation in wells and operation facilities,buckling of casing in cased-hole wells and well productivity reduction.Sand production control methods include restrictive production rate,mechanical methods(slotted liner,wire-wrapped screen,pre-packed screen,frac-pack,gravel pack,high-rate water pack)and chemical consolidation that chemical method is considered for more effectiveness in sand production alleviation due to increasing formation strength in near wellbore region.This review provides an overview on the laboratory and filed operation investigations of chemical remedy for sand production.Some used chemical agents and more common laboratory tests for evaluating the chemical performance in sand consolidation are introduced in this paper.Furthermore,the results of field operations and in-jections of chemicals into the desired formation are also reported.These results show that the chemical sand consolidation is more effective in newly perforated wells which have no sand production experi-ence and have a production history of less than two years.Finally,it was concluded that the main challenges in applying this method are permeability and capillary force reduction around the wellbore and selective injection into the targeted formation layers.展开更多
This study used the diethylene triamine pentaacetic acid(DTPA)-seawater(SW)system to modify the sandstone rock wettability and enhance oil recovery.The investigation involved conducting wettability measurement,Zeta po...This study used the diethylene triamine pentaacetic acid(DTPA)-seawater(SW)system to modify the sandstone rock wettability and enhance oil recovery.The investigation involved conducting wettability measurement,Zeta potential measurement,and spontaneous imbibition experiment.The introduction of 5%DTPA-sW solution resulted in a significant decrease in the rock-oil contact angle from 143°to 23,along with a reduction in the Zeta potential from-2.29 mV to-13.06 mV,thereby altering the rock surface charge and shifting its wettability from an oil-wet state to a strongly water-wet state.The presence or absence of potential determining ions(Ca^(2+),Mg^(2+),SO_(4)^(2-))in the solution did not impact the effectiveness of DTPA in changing the rock wettability.However,by tripling the concentration of these ions in the solution,the performance of 5%DTPA-SW solution in changing wettability was impaired.Additionally,spontaneous imbibition tests demonstrated that the 5%DTPA-SW solution led to an increase in oil recovery up to 39.6%.Thus,the optimum mass fraction of DTPA for changing sandstone wettability was determined to be5%.展开更多
Magnesium and aluminum alloys continually attract interest as lightweight structural materials for transport applications. However, joining these dissimilar alloys is very challenging. The main obstacle that hinders p...Magnesium and aluminum alloys continually attract interest as lightweight structural materials for transport applications. However, joining these dissimilar alloys is very challenging. The main obstacle that hinders progress in dissimilar Mg-Al joining is the formation of brittle intermetallic compounds(IMCs). As a solid-state joining technique, FSW is an excellent candidate to attenuate the deleterious IMC effects in dissimilar Al-Mg joining due to the inherent low heat inputs involved in the process. However, the IMCs, namely Al_(3)Mg_(2) and Al_(12)Mg_(17) phases, have also been reported to form during Al-Mg dissimilar FSW;their amount and thickness depend on the heat input involved;thus,the weld parameters used. Since the heat dissipated in the material during the welding process significantly affects the amount of IMCs,the heat input during FSW should be kept as low as possible to control and reduce the amount of IMCs. This review aims to critically discuss and evaluate the studies conducted in the dissimilar Al/Mg FSW through a scientometric analysis and also with a focus on the strategies recently applied to enhance joint quality. The scientometric analysis showed that the main research directions in Mg/Al FSW are the technological weldability of aluminum and magnesium during FSW, structural morphology, and mechanical properties of dissimilar welded joints. Considering the scope of application of the aforementioned joints, the low share of articles dealing with environmental degradation and operational cracking is surprising. This might be attributed to the need for well-developed strategies for obtaining high-quality and sustainable joints for applications. Thus, the second part of this review is conventional, focusing mainly on the new strategies for obtaining high-quality Mg/Al joints. It can be concluded that in addition to the necessity to optimum welding parameters to suppress the excessive heat to limit the amount and thickness of IMC formed and improve the overall joint quality, strategies such as using Zn interlayer, electric current assisted FSW(EAFSW), ultrasonic vibration FSW(UVa FSW), are considered effective in the elimination, reduction, and fragmentation of the brittle IMCs.展开更多
This paper presents a series of monotonically combined lateral loading tests to investigate the bearing capacity of the MSCs （modified suction caissons） in the saturated marine fine sand. The lateral loads were appl...This paper presents a series of monotonically combined lateral loading tests to investigate the bearing capacity of the MSCs （modified suction caissons） in the saturated marine fine sand. The lateral loads were applied under load- and displacement-controlled methods at the loading eccentricity ratios of 1.5, 2.0 and 2.5. Results show that, in the displacement-controlled test, the deflection-softening behavior of load-deflection curves for MSCs was observed, and the softening degree of the load-deflection response increased with the increasing external skirt length or the decreasing loading eccentricity. It was also found that the rotation center of the MSC at failure determined by the load-controlled method is slightly lower than that by the displacement-controlled method. The calculated MSC capacity based on the rotation center position in serviceability limit state is relatively conservative, compared with the calculated capacity based on the rotation center position in the ultimate limit state. In the limit state, the passive earth pressures opposite the loading direction under load- and displacement-controlled methods decrease by 46% and 74% corresponding to peak values, respectively; however, the passive earth pressures in the loading direction at failure only decrease by approximately 3% and 7%, compared with their peak values.展开更多
Cr-SiC nanocomposite coatings with various contents of SiC nanoparticles were prepared by electrodeposition in optimized Cr plating bath containing different concentrations of SiC nanoparticles. Direct current electro...Cr-SiC nanocomposite coatings with various contents of SiC nanoparticles were prepared by electrodeposition in optimized Cr plating bath containing different concentrations of SiC nanoparticles. Direct current electrocodeposition technique was used to deposit chromium layers with and without SiC nanoparticles on mild carbon steel. The effects of current density, stirring rate and concentration of nanoparticles in the plating bath were investigated. Scanning electron microscopy was used to study surface morphology. Energy dispersive analysis technique was used to verify the presence of SiC nanoparticles in the coated layers. The corrosion behaviors of coatings were investigated by potentiodynamic polarization and electrochemical impedance spectroscopy methods in 0.05 mol/L HCl, 1 mol/L NaOH and 3.5% NaCl （mass fraction）, respectively. Microhardness measurements and pin-on- disc tribometer technique were used to investigate the wear behavior of the coatings.展开更多
The influence of surface-modified silica(SiO_2) nanoparticles on the stability and pore plugging properties of foams in porous media was investigated in this study. The pore plugging ability of foams was estimated fro...The influence of surface-modified silica(SiO_2) nanoparticles on the stability and pore plugging properties of foams in porous media was investigated in this study. The pore plugging ability of foams was estimated from the pressure drop induced during foam propagation in porous media. The results clearly showed that the modified Si02 nanoparticlestabilized foam exhibited high stability, and the differential pressure increased in porous media by as much as three times.The addition of SiO_2 nanoparticles to the foaming dispersions further mitigated the adverse effect of oil toward the foam pore plugging ability. Consequently, the oil recovery increased in the presence of nanoparticles by approximately 15%during the enhanced oil recovery experiment. The study suggested that the addition of surface-modified silica nanoparticles to the surfactant solution could considerably improve the conventional foam stability and pore plugging performance in porous media.展开更多
Production,processing and transportation of natural gases can be significantly affected by clathrate hydrates.Knowing the gas analysis is crucial to predict the right conditions for hydrate formation.Nevertheless,Katz...Production,processing and transportation of natural gases can be significantly affected by clathrate hydrates.Knowing the gas analysis is crucial to predict the right conditions for hydrate formation.Nevertheless,Katz gas gravity method can be used for initial estimation of hydrate formation temperature （HFT） under the circumstances of indeterminate gas composition.So far several correlations have been proposed for gas gravity method,in which the most accurate and reliable one has belonged to Bahadori and Vuthaluru.The main objective of this study is to present a simple and yet accurate correlation for fast prediction of sweet natural gases HFT based on the fit to Katz gravity chart.By reviewing the error analysis results,one can discover that the new proposed correlation has the best estimation capability among the widely accepted existing correlations within the investigated range.展开更多
The potential of di-(m-Formylphenol)-1,2-cyclohexandiimine as an environmentally friendly corrosion inhibitor for steel was investigated in 1 mol/L HCl using potentiodynamic polarization, electrochemical impedance spe...The potential of di-(m-Formylphenol)-1,2-cyclohexandiimine as an environmentally friendly corrosion inhibitor for steel was investigated in 1 mol/L HCl using potentiodynamic polarization, electrochemical impedance spectroscopy and chronoamperometry measurements. All electrochemical measurements suggest that this compound is an excellent corrosion inhibitor for mild steel and the inhibition efficiency increases with the increase in inhibitor concentration. The effect of temperature on the corrosion behavior of mild steel with the addition of the Schiff base was studied in the temperature range from 25 °C to 65 °C. It is found that the adsorption of this inhibitor follows the Langmuir adsorption isotherms. The value of activation energy and the thermodynamic parameters such as ΔHads, ΔSads, Kads and ΔGads were calculated by the corrosion currents at different temperatures using the adsorption isotherm. The morphology of mild steel surface in the absence and presence of inhibitor was examined by scanning electron microscopy(SEM) images.展开更多
Scaled physical model tests for steam breakthrough were conducted based on the analysis of mechanisms and influence factors of steam breakthrough. Physical simulation results showed that at the initial steam breakthro...Scaled physical model tests for steam breakthrough were conducted based on the analysis of mechanisms and influence factors of steam breakthrough. Physical simulation results showed that at the initial steam breakthrough, preferential flow channels were formed in narrow sand packs and most residual oil left in these channels was immobile. This shortened the steam breakthrough time of follow-up steam flooding and decreased the increment of oil recovery efficiency. Steam breakthrough occurred easily for a smaller producer-injector spacing, and a bigger difference in physical properties between fluids and rock. Steam breakthrough is more likely to occur at a larger formation permeability （k）, greater steam displacement velocity （u） and smaller producer-injector spacing （L）. Steam breakthrough time is a function of the parameter group （uk/L）, i.e. tb=3.2151 （uk/L）^-0.5142. A non piston-like displacement model was built based on steam breakthrough observation for a steam stimulated well in the Jinglou Oilfield, Henan Oilfield Company. The steam volume swept in different directions could be obtained from inter-well permeability capacity and breakthrough angle, and the steam swept pore volume （SSPV） was also determined. Numerical simulation showed that steam sweep efficiency reached its peak value when a slug of profile control agent （slug size 10%-15% SSPV） was set at one half of the inter-well spacing. Field test with 12.5% SSPV of profile control agents in the Jinglou Oilfield achieved success in sealing breakthrough channels and good production performance of adjacent producers.展开更多
An industrial scale propylene production via oxidative dehydrogenation of propane （ODHP） in multi-tubular re- actors was modeled. Multi-tubular fixed-bed reactor used for ODHP process, employing 10000 of small diame...An industrial scale propylene production via oxidative dehydrogenation of propane （ODHP） in multi-tubular re- actors was modeled. Multi-tubular fixed-bed reactor used for ODHP process, employing 10000 of small diameter tubes immersed in a shell through a proper coolant flows. Herein, a theory-based pseudo-homogeneous model to describe the operation of a fixed bed reactor for the ODHP to correspondence olefln over V2O5/γ-Al203 catalyst was presented. Steady state one dimensional model has been developed to identify the operation parameters and to describe the propane and oxygen conversions, gas process and coolant temperatures, as well as other pa- rameters affecting the reactor performance such as pressure. Furthermore, the applied model showed that a double-bed multitubular reactor with intermediate air injection scheme was superior to a single-bed design due to the increasing of propylene selectivity while operating under lower oxygen partial pressures resulting in propane conversion of about 37.3%. The optimized length of the reactor needed to reach 100% conversion of the oxygen was theoretically determined. For the single-bed reactor the optimized length of 11.96 m including 0.5 m of inert section at the entrance region and for the double-bed reactor design the optimized lengths of 5.72 m for the first and 7.32 m for the second reactor were calculated. Ultimately, the use of a distributed oxygen feed with limited number of injection points indicated a significant improvement on the reactor performance in terms of propane conversion and propylene selectivity. Besides, this concept could overcome the reactor run- away temperature problem and enabled operations at the wider range of conditions to obtain enhanced propyl- ene production in an industrial scale reactor.展开更多
Mikbi intrusion(MI) is a part of the Neoproterozoic Nubian Shield located along the NE-SW trending major fracture zones prevailing southern Eastern Desert of Egypt. In this study, we present for the first time detaile...Mikbi intrusion(MI) is a part of the Neoproterozoic Nubian Shield located along the NE-SW trending major fracture zones prevailing southern Eastern Desert of Egypt. In this study, we present for the first time detailed mineralogical and bulk-rock geochemical data to infer some constraints on the parental magma genesis and to understand the tectonic processes contributed to MI formation. Lithologically, it is composed of fresh peridotite, clinopyroxenite, hornblendite, anorthosite, gabbronorite, pyroxene amphibole gabbro, amphibole gabbro and diorite. All rocks have low Th/La ratios(mostly <0.2) and lack positive Zr and Th anomalies excluding significant crustal contamination. They show very low concentrations of Nb, Ta, Zr and Hf together with sub-chondritic ratios of Nb/Ta(2-15) and Zr/Hf(19-35),suggesting that their mantle source was depleted by earlier melting extraction event. The oxygen fugacity(logfO_2) estimated from diorite biotite is around the nickel-nickel oxide buffer(NNO) indicating crystallization from a relatively oxidized magma. Amphiboles in the studied mafic-ultramafic rocks indicate relative oxygen fugacity(i.e. ΔNNO; nickel-nickel oxide) of 0.28-3 and were in equilibrium mostly with 3.77-8.24 wt.% H_2 O_(melt)(i.e. water content in the melt), consistent with the typical values of subduction-related magmas. Moreover, pressure estimates(0.53-6.79 kbar) indicate polybaric crystallization and suggest that the magma chamber(s) was located at relatively shallow crustal levels. The enrichment in LILE(e.g., Cs, Ba, K and Sr) and the depletion in HFSE(e.g., Th and Nb) relative to primitive mantle are consistent with island arc signature. The olivine, pyroxene and amphibole compositions also reflect arc affinity. These inferences suggest that their primary magma was derived from partial melting of a mantle source that formerly metasomatized in a subduction zone setting. Clinopyroxene and bulkrock data are consistent with orogenic tholeiitic affinity. Consequently, the mineral and bulk-rock chemistry strongly indicate crystallization from hydrous tholeiitic magma. Moreover, their trace element patterns are subparallel indicating that the various rock types possibly result from differentiation of the same primary magma. These petrological, mineralogical and geochemical characteristics show that the MI is a typical Alaskan-type complex.展开更多
With shale oil reservoir pressure depletion and recovery of hydrocarbons from formations, the fracture apertures and conductivity are subject to reduction due to the interaction between stress effects and proppants. S...With shale oil reservoir pressure depletion and recovery of hydrocarbons from formations, the fracture apertures and conductivity are subject to reduction due to the interaction between stress effects and proppants. Suppose most of the proppants were concentrated in dominant fractures rather than sparsely allocated in the fracture network, the fracture conductivity would be less influenced by the induced stress effect. However, the merit of uniformly distributed proppants in the fracture network is that it increases the contact area for the injection gas with the shale matrix. In this paper, we address the question whether we should exploit or confine the fracture complexity for CO2-EOR in shale oil reservoirs. Two proppant transport scenarios were simulated in this paper： Case 1-the proppant is uniformly distributed in the complex fracture system, propagating a partially propped or un-propped fracture network; Case 2-the proppant primarily settles in simple planar fractures. A series of sensitivity studies of the fracture conductivity were performed to investigate the conductivity requirements in order to more efficiently produce from the shale reservoirs. Our simulation results in this paper show the potential of CO2 huff-n-puff to improve oil recovery in shale oil reservoirs. Simulation results indicate that the ultra-low permeability shales require an interconnected fracture network to maximize shale oil recovery in a reasonable time period. The well productivity of a fracture network with a conductivity of 4 mD ft achieves a better performance than that of planar fractures with an infinite conductivity. However, when the conductivity of fracture networks is inadequate,the planar fracture treatment design maybe a favorable choice. The available literature provides limited information on the relationship between fracture treatment design and the applicability of CO2 huff-n-puff in very low permeability shale formations. Very limited field test or laboratory data are available on the investigation of conductivity requirements for cyclic CO2 injection in shale oil reservoirs. In the context of CO2 huff-n-puff EOR, the effect of fracture complexity on well productivity was examined by simulation approaches.展开更多
The present work investigates the effect of filler metals and heat input on weld bead geometry and mechanical properties of alloy316 welded by using GTAW.ER309 L,ER316 L and ERNi Cr Mo-3 filler metals,are applied to s...The present work investigates the effect of filler metals and heat input on weld bead geometry and mechanical properties of alloy316 welded by using GTAW.ER309 L,ER316 L and ERNi Cr Mo-3 filler metals,are applied to study their effect on the weldment.Weld defects are examined using radiographic testing.The mechanical properties of welds are evaluated through uniaxial testing,hardness measuring,and bending test.The mechanical properties and cooling rate decrease with increasing heat input.Tensile strength,yield stress and percentage elongation of weldments using three fillers are determined.Best results are obtained using ERNi Cr Mo-3.Besides,weld nugget area,cooling time and solidification time increases with increasing heat input.Finally,applying bending test on weld samples,cracks,tearing and surface defects are not observed.展开更多
Nanofluids and low-salinity water(LSW)flooding are two novel techniques for enhanced oil recovery.Despite some efforts on investigating benefits of each method,the pros and cons of their combined application need to b...Nanofluids and low-salinity water(LSW)flooding are two novel techniques for enhanced oil recovery.Despite some efforts on investigating benefits of each method,the pros and cons of their combined application need to be evaluated.This work sheds light on performance of LSW augmented with nanoparticles through examining wettability alteration and the amount of incremental oil recovery during the displacement process.To this end,nanofluids were prepared by dispersing silica nanoparticles(0.1 wt%,0.25 wt%,0.5 wt% and 0.75 wt%)in 2,10,20 and 100 times diluted samples of Persian Gulf seawater.Contact angle measurements revealed a crucial role of temperature,where no wettability alteration occurred up to 80 ℃.Also,an optimum wettability state(with contact angle 22°)was detected with a 20 times diluted sample of seawater augmented with 0.25 wt% silica nanoparticles.Also,extreme dilution(herein 100 times)will be of no significance.Throughout micromodel flooding,it was found that in an oil-wet condition,a combination of silica nanoparticles dispersed in 20 times diluted brine had the highest displacement efficiency compared to silica nanofluids prepared with deionized water.Finally,by comparing oil recoveries in both water-and oil-wet micromodels,it was concluded that nanoparticles could enhance applicability of LSW via strengthening wettability alteration toward a favorable state and improving the sweep efficiency.展开更多
This study aims at evaluating the performance of thiamine as a new eco-friendly shale inhibitor in water-based drilling fluids(WBDFs).The evaluation experiments include sedimentation,bentonite inhibition,filtration,ze...This study aims at evaluating the performance of thiamine as a new eco-friendly shale inhibitor in water-based drilling fluids(WBDFs).The evaluation experiments include sedimentation,bentonite inhibition,filtration,zeta potential,thermal gravimetric analysis,scanning electron microscopy,X-ray diffraction,shale cuttings recovery,linear swelling and Fourier transform infrared spectroscopy(FTIR).The performance of thiamine was compared to potassium chloride.In contrast to deionized water,the aqueous solution of thiamine exhibited greater power to inhibit montmorillonite(Mt)dispersion,much more Mt loading capacity(280 g/L)and fluid loss,lower Mt mass loss,larger aggregated Mt particles,lower interlayer space of the Mt particles,less shale cuttings disintegration and lower linear swelling.Adsorption of thiamine on Mt led to a significant shift in the value of zeta potential(from-17.1 to+8.54 mV).Thiamine demonstrated superior inhibitive performance than potassium chloride.FTIR analysis confirmed that thiamine is adsorbed on Mt particles.The compatibility test revealed the compatibility of thiamine with conventional WBDF additives.It was concluded that the main probable inhibition mechanisms of thiamine are the cation exchange and Mt surface coating.In view of its prominent inhibition capacity and great environmental acceptability,thiamine is a promising inhibitor for drilling in water-sensitive formations.展开更多
基金supported by the National Natural Science Foundation of China(No.41802179)Sichuan Science and Technology Program(No.2019YFH0037)the Foundation of the State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum,Beijing(No.PRP/open-1906).
文摘Recently, significant oil discoveries have been made in the shallower pay zones of the Jurassic Badaowan Formation (J_(1)b) in the Mahu Sag, Junggar Basin, Northwest China. However, little work has been done on the geochemical characteristics and origins of the oil in the J_(1)b reservoir. This study analyzes 44 oil and 14 source rock samples from the area in order to reveal their organic geochemical characteristics and the origins of the oils. The J_(1)b oils are characterized by a low Pr/Ph ratio and high β-carotene and gammacerane indices, which indicate that they were mainly generated from source rocks deposited in a hypersaline environment. The oils are also extremely enhanced in C_(29) regular steranes, possibly derived from halophilic algae. Oil-source correlation shows that the oils were derived from the Lower Permian Fengcheng Formation (P_(1)f) source rocks, which were deposited in a strongly stratified and highly saline water column with a predominance of algal/bacterial input in the organic matter. The source rocks of the Middle Permian lower-Wuerhe Formation (P_(2)w), which were deposited in fresh to slightly saline water conditions with a greater input of terrigenous organic matter, make only a minor contribution to the J_(1)b oils. The reconstruction of the oil accumulation process shows that the J_(1)b oil reservoir may have been twice charged during Late Jurassic–Early Cretaceous and the Paleogene–Neogene, respectively. A large amount volume of hydrocarbons generated in the P_(1)f source rock and leaked from T_(1)b oil reservoirs migrated along faults connecting source beds and shallow-buried secondary faults into Jurassic traps, resulting in large-scale accumulations in J_(1)b. These results are crucial for understanding the petroleum system of the Mahu Sag and will provide valuable guidance for petroleum exploration in the shallower formations in the slope area of the sag.
文摘Development and production from fractured reservoirs require extensive knowledge about the reservoir structures and in situ stress regimes.For this,this paper investigates fractures and the parameters(aperture and density)through a combination of wellbore data and geomechanical laboratory testing in three separate wells in the Asmari reservoir,Zagros Belt,Iran.The Asmari reservoir(Oligo-Miocene)consists mainly of calcitic and dolomitic rocks in depths of 2000e3000 m.Based on the observation of features in several wellbores,the orientation and magnitude of the in situ stresses along with their influence on reservoir-scale geological structures and neotectonics were determined.The study identifies two regional tectonic fracture settings in the reservoir:one set associated with longitudinal and diagonal wrinkling,and the other related to faulting.The former,which is mainly of open fractures with a large aperture,is dominant and generally oriented in the N45°-90°W direction while the latter is obliquely oriented relative to the bedding and characterized by N45°-90°E.The largest aperture is found in open fractures that are longitudinal and developed in the dolomitic zones within a complex stress regime.Moreover,analysis of drilling-induced fractures(DIFs)and borehole breakouts(BBs)from the image logs revealed that the maximum horizontal stress(SHmax)orientation in these three wells is consistent with the NE-SW regional trend of the SHmax(maximum principal horizontal stress)in the Zagros Belt.Likewise,the stress magnitude obtained from geomechanical testing and poroelastic equations confirmed a variation in stress regime from normal to reverse,which changes in regard to active faults in the study area.Finally,a relationship between the development degree of open fractures and in situ stress regime was found.This means that in areas where the stress regime is complex and reverse,fractures would exhibit higher density,dip angle,and larger apertures.
文摘There are several advantages to the MIG(Metal Inert Gas)process,which explains its increased use in variouswelding sectors,such as automotive,marine,and construction.A variant of the MIG process,where the sameequipment is employed except for the deposition of a thin layer of flux before the welding operation,is the AMIG(Activated Metal Inert Gas)technique.This study focuses on investigating the impact of physical properties ofindividual metallic oxide fluxes for 304L stainless steel welding joint morphology and to what extent it can helpdetermine a relationship among weld depth penetration,the aspect ratio,and the input physical properties ofthe oxides.Five types of oxides,TiO_(2),SiO_(2),Fe_(2)O_(3),Cr_(2)O_(3),and Mn_(2)O_(3),are tested on butt joint design withoutpreparation of the edges.A robust algorithm based on the particle swarm optimization(PSO)technique is appliedto optimally tune the models’parameters,such as the quadratic error between the actual outputs(depth and aspectratio),and the error estimated by the models’outputs is minimized.The results showed that the proposed PSOmodel is first and foremost robust against uncertainties in measurement devices and modeling errors,and second,that it is capable of accurately representing and quantifying the weld depth penetration and the weld aspect ratioto the oxides’thermal properties.
文摘This article examines the dynamics for stochastic plate equations with linear memory in the case of bounded domain. We investigate the existence of solutions and bounded absorbing set by using the uniform pullback attractors on the tails estimates, and the asymptotic compactness of the random dynamical system is proved by decomposition method, and then we obtain the existence of a random attractor.
基金supported by the Directorate of Exploration of the NIOC
文摘After two well tests in the Asmari well#A, located in the North Dezful zone, it was concluded that in the Jurassic Mus/Alan/Neyriz and Upper Sargelu reservoirs, highly mature colorless oil and gas were trapped, including 4%-6% H2 S. The alternation of Garau shale and the Gotnia anhydrite seal was so efficient that it did not allow the upward migration of petroleum from Jurassic reservoirs to higher levels. Descriptive ratios, chromatograms, pick correlation and cross plots demonstrated that the oil and gas have been derived from a TOC-enriched sequence, consisting of the base of the Garau and the top of the Sargelu Formations. This highly organic matter-rich sequence is traceable as an oil shale in other parts of the North Dezful zone, such as the Gashun section. The petroleum accumulations in both reservoirs are identical, have the same maturity and the same source. Diagrams of δ13 C2 versus δ13 C3, δ13 C1 versus wetness of gas(C1/C2+C3) and δ13 C1 versus δDC1 suggest that the gas is derived from a highly mature source. There are indications of TSR effects on the original petroleum that could have changed the volumetric and isotopic composition of the oil and gas. This result requires more careful study of the petroleum components to be undertaken.
文摘Sand production from loosely consolidated reservoirs is one of the critical issues in the oil and gas in-dustry all around the world that can cause many problems,such as erosion of surface and well equip-ment,sand accumulation in wells and operation facilities,buckling of casing in cased-hole wells and well productivity reduction.Sand production control methods include restrictive production rate,mechanical methods(slotted liner,wire-wrapped screen,pre-packed screen,frac-pack,gravel pack,high-rate water pack)and chemical consolidation that chemical method is considered for more effectiveness in sand production alleviation due to increasing formation strength in near wellbore region.This review provides an overview on the laboratory and filed operation investigations of chemical remedy for sand production.Some used chemical agents and more common laboratory tests for evaluating the chemical performance in sand consolidation are introduced in this paper.Furthermore,the results of field operations and in-jections of chemicals into the desired formation are also reported.These results show that the chemical sand consolidation is more effective in newly perforated wells which have no sand production experi-ence and have a production history of less than two years.Finally,it was concluded that the main challenges in applying this method are permeability and capillary force reduction around the wellbore and selective injection into the targeted formation layers.
文摘This study used the diethylene triamine pentaacetic acid(DTPA)-seawater(SW)system to modify the sandstone rock wettability and enhance oil recovery.The investigation involved conducting wettability measurement,Zeta potential measurement,and spontaneous imbibition experiment.The introduction of 5%DTPA-sW solution resulted in a significant decrease in the rock-oil contact angle from 143°to 23,along with a reduction in the Zeta potential from-2.29 mV to-13.06 mV,thereby altering the rock surface charge and shifting its wettability from an oil-wet state to a strongly water-wet state.The presence or absence of potential determining ions(Ca^(2+),Mg^(2+),SO_(4)^(2-))in the solution did not impact the effectiveness of DTPA in changing the rock wettability.However,by tripling the concentration of these ions in the solution,the performance of 5%DTPA-SW solution in changing wettability was impaired.Additionally,spontaneous imbibition tests demonstrated that the 5%DTPA-SW solution led to an increase in oil recovery up to 39.6%.Thus,the optimum mass fraction of DTPA for changing sandstone wettability was determined to be5%.
基金sponsored by the Prince Sattam bin Abdulaziz University via project number 2023/RV/018。
文摘Magnesium and aluminum alloys continually attract interest as lightweight structural materials for transport applications. However, joining these dissimilar alloys is very challenging. The main obstacle that hinders progress in dissimilar Mg-Al joining is the formation of brittle intermetallic compounds(IMCs). As a solid-state joining technique, FSW is an excellent candidate to attenuate the deleterious IMC effects in dissimilar Al-Mg joining due to the inherent low heat inputs involved in the process. However, the IMCs, namely Al_(3)Mg_(2) and Al_(12)Mg_(17) phases, have also been reported to form during Al-Mg dissimilar FSW;their amount and thickness depend on the heat input involved;thus,the weld parameters used. Since the heat dissipated in the material during the welding process significantly affects the amount of IMCs,the heat input during FSW should be kept as low as possible to control and reduce the amount of IMCs. This review aims to critically discuss and evaluate the studies conducted in the dissimilar Al/Mg FSW through a scientometric analysis and also with a focus on the strategies recently applied to enhance joint quality. The scientometric analysis showed that the main research directions in Mg/Al FSW are the technological weldability of aluminum and magnesium during FSW, structural morphology, and mechanical properties of dissimilar welded joints. Considering the scope of application of the aforementioned joints, the low share of articles dealing with environmental degradation and operational cracking is surprising. This might be attributed to the need for well-developed strategies for obtaining high-quality and sustainable joints for applications. Thus, the second part of this review is conventional, focusing mainly on the new strategies for obtaining high-quality Mg/Al joints. It can be concluded that in addition to the necessity to optimum welding parameters to suppress the excessive heat to limit the amount and thickness of IMC formed and improve the overall joint quality, strategies such as using Zn interlayer, electric current assisted FSW(EAFSW), ultrasonic vibration FSW(UVa FSW), are considered effective in the elimination, reduction, and fragmentation of the brittle IMCs.
基金supported by the National Natural Science Foundation of China(Grant Nos.51379118 and 51639002)SDUST Scientific Found(Grant No.2015KYTD104)
文摘This paper presents a series of monotonically combined lateral loading tests to investigate the bearing capacity of the MSCs （modified suction caissons） in the saturated marine fine sand. The lateral loads were applied under load- and displacement-controlled methods at the loading eccentricity ratios of 1.5, 2.0 and 2.5. Results show that, in the displacement-controlled test, the deflection-softening behavior of load-deflection curves for MSCs was observed, and the softening degree of the load-deflection response increased with the increasing external skirt length or the decreasing loading eccentricity. It was also found that the rotation center of the MSC at failure determined by the load-controlled method is slightly lower than that by the displacement-controlled method. The calculated MSC capacity based on the rotation center position in serviceability limit state is relatively conservative, compared with the calculated capacity based on the rotation center position in the ultimate limit state. In the limit state, the passive earth pressures opposite the loading direction under load- and displacement-controlled methods decrease by 46% and 74% corresponding to peak values, respectively; however, the passive earth pressures in the loading direction at failure only decrease by approximately 3% and 7%, compared with their peak values.
文摘Cr-SiC nanocomposite coatings with various contents of SiC nanoparticles were prepared by electrodeposition in optimized Cr plating bath containing different concentrations of SiC nanoparticles. Direct current electrocodeposition technique was used to deposit chromium layers with and without SiC nanoparticles on mild carbon steel. The effects of current density, stirring rate and concentration of nanoparticles in the plating bath were investigated. Scanning electron microscopy was used to study surface morphology. Energy dispersive analysis technique was used to verify the presence of SiC nanoparticles in the coated layers. The corrosion behaviors of coatings were investigated by potentiodynamic polarization and electrochemical impedance spectroscopy methods in 0.05 mol/L HCl, 1 mol/L NaOH and 3.5% NaCl （mass fraction）, respectively. Microhardness measurements and pin-on- disc tribometer technique were used to investigate the wear behavior of the coatings.
基金Ministry of Higher Education (Vot No. Q.J130000.2542.08H61)Universiti Teknologi (UTM) Malaysia for supporting this research
文摘The influence of surface-modified silica(SiO_2) nanoparticles on the stability and pore plugging properties of foams in porous media was investigated in this study. The pore plugging ability of foams was estimated from the pressure drop induced during foam propagation in porous media. The results clearly showed that the modified Si02 nanoparticlestabilized foam exhibited high stability, and the differential pressure increased in porous media by as much as three times.The addition of SiO_2 nanoparticles to the foaming dispersions further mitigated the adverse effect of oil toward the foam pore plugging ability. Consequently, the oil recovery increased in the presence of nanoparticles by approximately 15%during the enhanced oil recovery experiment. The study suggested that the addition of surface-modified silica nanoparticles to the surfactant solution could considerably improve the conventional foam stability and pore plugging performance in porous media.
文摘Production,processing and transportation of natural gases can be significantly affected by clathrate hydrates.Knowing the gas analysis is crucial to predict the right conditions for hydrate formation.Nevertheless,Katz gas gravity method can be used for initial estimation of hydrate formation temperature （HFT） under the circumstances of indeterminate gas composition.So far several correlations have been proposed for gas gravity method,in which the most accurate and reliable one has belonged to Bahadori and Vuthaluru.The main objective of this study is to present a simple and yet accurate correlation for fast prediction of sweet natural gases HFT based on the fit to Katz gravity chart.By reviewing the error analysis results,one can discover that the new proposed correlation has the best estimation capability among the widely accepted existing correlations within the investigated range.
文摘The potential of di-(m-Formylphenol)-1,2-cyclohexandiimine as an environmentally friendly corrosion inhibitor for steel was investigated in 1 mol/L HCl using potentiodynamic polarization, electrochemical impedance spectroscopy and chronoamperometry measurements. All electrochemical measurements suggest that this compound is an excellent corrosion inhibitor for mild steel and the inhibition efficiency increases with the increase in inhibitor concentration. The effect of temperature on the corrosion behavior of mild steel with the addition of the Schiff base was studied in the temperature range from 25 °C to 65 °C. It is found that the adsorption of this inhibitor follows the Langmuir adsorption isotherms. The value of activation energy and the thermodynamic parameters such as ΔHads, ΔSads, Kads and ΔGads were calculated by the corrosion currents at different temperatures using the adsorption isotherm. The morphology of mild steel surface in the absence and presence of inhibitor was examined by scanning electron microscopy(SEM) images.
文摘Scaled physical model tests for steam breakthrough were conducted based on the analysis of mechanisms and influence factors of steam breakthrough. Physical simulation results showed that at the initial steam breakthrough, preferential flow channels were formed in narrow sand packs and most residual oil left in these channels was immobile. This shortened the steam breakthrough time of follow-up steam flooding and decreased the increment of oil recovery efficiency. Steam breakthrough occurred easily for a smaller producer-injector spacing, and a bigger difference in physical properties between fluids and rock. Steam breakthrough is more likely to occur at a larger formation permeability （k）, greater steam displacement velocity （u） and smaller producer-injector spacing （L）. Steam breakthrough time is a function of the parameter group （uk/L）, i.e. tb=3.2151 （uk/L）^-0.5142. A non piston-like displacement model was built based on steam breakthrough observation for a steam stimulated well in the Jinglou Oilfield, Henan Oilfield Company. The steam volume swept in different directions could be obtained from inter-well permeability capacity and breakthrough angle, and the steam swept pore volume （SSPV） was also determined. Numerical simulation showed that steam sweep efficiency reached its peak value when a slug of profile control agent （slug size 10%-15% SSPV） was set at one half of the inter-well spacing. Field test with 12.5% SSPV of profile control agents in the Jinglou Oilfield achieved success in sealing breakthrough channels and good production performance of adjacent producers.
文摘An industrial scale propylene production via oxidative dehydrogenation of propane （ODHP） in multi-tubular re- actors was modeled. Multi-tubular fixed-bed reactor used for ODHP process, employing 10000 of small diameter tubes immersed in a shell through a proper coolant flows. Herein, a theory-based pseudo-homogeneous model to describe the operation of a fixed bed reactor for the ODHP to correspondence olefln over V2O5/γ-Al203 catalyst was presented. Steady state one dimensional model has been developed to identify the operation parameters and to describe the propane and oxygen conversions, gas process and coolant temperatures, as well as other pa- rameters affecting the reactor performance such as pressure. Furthermore, the applied model showed that a double-bed multitubular reactor with intermediate air injection scheme was superior to a single-bed design due to the increasing of propylene selectivity while operating under lower oxygen partial pressures resulting in propane conversion of about 37.3%. The optimized length of the reactor needed to reach 100% conversion of the oxygen was theoretically determined. For the single-bed reactor the optimized length of 11.96 m including 0.5 m of inert section at the entrance region and for the double-bed reactor design the optimized lengths of 5.72 m for the first and 7.32 m for the second reactor were calculated. Ultimately, the use of a distributed oxygen feed with limited number of injection points indicated a significant improvement on the reactor performance in terms of propane conversion and propylene selectivity. Besides, this concept could overcome the reactor run- away temperature problem and enabled operations at the wider range of conditions to obtain enhanced propyl- ene production in an industrial scale reactor.
文摘Mikbi intrusion(MI) is a part of the Neoproterozoic Nubian Shield located along the NE-SW trending major fracture zones prevailing southern Eastern Desert of Egypt. In this study, we present for the first time detailed mineralogical and bulk-rock geochemical data to infer some constraints on the parental magma genesis and to understand the tectonic processes contributed to MI formation. Lithologically, it is composed of fresh peridotite, clinopyroxenite, hornblendite, anorthosite, gabbronorite, pyroxene amphibole gabbro, amphibole gabbro and diorite. All rocks have low Th/La ratios(mostly <0.2) and lack positive Zr and Th anomalies excluding significant crustal contamination. They show very low concentrations of Nb, Ta, Zr and Hf together with sub-chondritic ratios of Nb/Ta(2-15) and Zr/Hf(19-35),suggesting that their mantle source was depleted by earlier melting extraction event. The oxygen fugacity(logfO_2) estimated from diorite biotite is around the nickel-nickel oxide buffer(NNO) indicating crystallization from a relatively oxidized magma. Amphiboles in the studied mafic-ultramafic rocks indicate relative oxygen fugacity(i.e. ΔNNO; nickel-nickel oxide) of 0.28-3 and were in equilibrium mostly with 3.77-8.24 wt.% H_2 O_(melt)(i.e. water content in the melt), consistent with the typical values of subduction-related magmas. Moreover, pressure estimates(0.53-6.79 kbar) indicate polybaric crystallization and suggest that the magma chamber(s) was located at relatively shallow crustal levels. The enrichment in LILE(e.g., Cs, Ba, K and Sr) and the depletion in HFSE(e.g., Th and Nb) relative to primitive mantle are consistent with island arc signature. The olivine, pyroxene and amphibole compositions also reflect arc affinity. These inferences suggest that their primary magma was derived from partial melting of a mantle source that formerly metasomatized in a subduction zone setting. Clinopyroxene and bulkrock data are consistent with orogenic tholeiitic affinity. Consequently, the mineral and bulk-rock chemistry strongly indicate crystallization from hydrous tholeiitic magma. Moreover, their trace element patterns are subparallel indicating that the various rock types possibly result from differentiation of the same primary magma. These petrological, mineralogical and geochemical characteristics show that the MI is a typical Alaskan-type complex.
基金supported by the Science Foundation of China University of Petroleum-Beijing at Karamay (No. KL01JB201700003)Xinjiang Uygur Autonomous Region Tianchi 100 Talent Plan
文摘With shale oil reservoir pressure depletion and recovery of hydrocarbons from formations, the fracture apertures and conductivity are subject to reduction due to the interaction between stress effects and proppants. Suppose most of the proppants were concentrated in dominant fractures rather than sparsely allocated in the fracture network, the fracture conductivity would be less influenced by the induced stress effect. However, the merit of uniformly distributed proppants in the fracture network is that it increases the contact area for the injection gas with the shale matrix. In this paper, we address the question whether we should exploit or confine the fracture complexity for CO2-EOR in shale oil reservoirs. Two proppant transport scenarios were simulated in this paper： Case 1-the proppant is uniformly distributed in the complex fracture system, propagating a partially propped or un-propped fracture network; Case 2-the proppant primarily settles in simple planar fractures. A series of sensitivity studies of the fracture conductivity were performed to investigate the conductivity requirements in order to more efficiently produce from the shale reservoirs. Our simulation results in this paper show the potential of CO2 huff-n-puff to improve oil recovery in shale oil reservoirs. Simulation results indicate that the ultra-low permeability shales require an interconnected fracture network to maximize shale oil recovery in a reasonable time period. The well productivity of a fracture network with a conductivity of 4 mD ft achieves a better performance than that of planar fractures with an infinite conductivity. However, when the conductivity of fracture networks is inadequate,the planar fracture treatment design maybe a favorable choice. The available literature provides limited information on the relationship between fracture treatment design and the applicability of CO2 huff-n-puff in very low permeability shale formations. Very limited field test or laboratory data are available on the investigation of conductivity requirements for cyclic CO2 injection in shale oil reservoirs. In the context of CO2 huff-n-puff EOR, the effect of fracture complexity on well productivity was examined by simulation approaches.
文摘The present work investigates the effect of filler metals and heat input on weld bead geometry and mechanical properties of alloy316 welded by using GTAW.ER309 L,ER316 L and ERNi Cr Mo-3 filler metals,are applied to study their effect on the weldment.Weld defects are examined using radiographic testing.The mechanical properties of welds are evaluated through uniaxial testing,hardness measuring,and bending test.The mechanical properties and cooling rate decrease with increasing heat input.Tensile strength,yield stress and percentage elongation of weldments using three fillers are determined.Best results are obtained using ERNi Cr Mo-3.Besides,weld nugget area,cooling time and solidification time increases with increasing heat input.Finally,applying bending test on weld samples,cracks,tearing and surface defects are not observed.
文摘Nanofluids and low-salinity water(LSW)flooding are two novel techniques for enhanced oil recovery.Despite some efforts on investigating benefits of each method,the pros and cons of their combined application need to be evaluated.This work sheds light on performance of LSW augmented with nanoparticles through examining wettability alteration and the amount of incremental oil recovery during the displacement process.To this end,nanofluids were prepared by dispersing silica nanoparticles(0.1 wt%,0.25 wt%,0.5 wt% and 0.75 wt%)in 2,10,20 and 100 times diluted samples of Persian Gulf seawater.Contact angle measurements revealed a crucial role of temperature,where no wettability alteration occurred up to 80 ℃.Also,an optimum wettability state(with contact angle 22°)was detected with a 20 times diluted sample of seawater augmented with 0.25 wt% silica nanoparticles.Also,extreme dilution(herein 100 times)will be of no significance.Throughout micromodel flooding,it was found that in an oil-wet condition,a combination of silica nanoparticles dispersed in 20 times diluted brine had the highest displacement efficiency compared to silica nanofluids prepared with deionized water.Finally,by comparing oil recoveries in both water-and oil-wet micromodels,it was concluded that nanoparticles could enhance applicability of LSW via strengthening wettability alteration toward a favorable state and improving the sweep efficiency.
文摘This study aims at evaluating the performance of thiamine as a new eco-friendly shale inhibitor in water-based drilling fluids(WBDFs).The evaluation experiments include sedimentation,bentonite inhibition,filtration,zeta potential,thermal gravimetric analysis,scanning electron microscopy,X-ray diffraction,shale cuttings recovery,linear swelling and Fourier transform infrared spectroscopy(FTIR).The performance of thiamine was compared to potassium chloride.In contrast to deionized water,the aqueous solution of thiamine exhibited greater power to inhibit montmorillonite(Mt)dispersion,much more Mt loading capacity(280 g/L)and fluid loss,lower Mt mass loss,larger aggregated Mt particles,lower interlayer space of the Mt particles,less shale cuttings disintegration and lower linear swelling.Adsorption of thiamine on Mt led to a significant shift in the value of zeta potential(from-17.1 to+8.54 mV).Thiamine demonstrated superior inhibitive performance than potassium chloride.FTIR analysis confirmed that thiamine is adsorbed on Mt particles.The compatibility test revealed the compatibility of thiamine with conventional WBDF additives.It was concluded that the main probable inhibition mechanisms of thiamine are the cation exchange and Mt surface coating.In view of its prominent inhibition capacity and great environmental acceptability,thiamine is a promising inhibitor for drilling in water-sensitive formations.
