The Evaluation of Liquefied Petroleum Gas (LPG) Utilization as an Alternative Automobile Fuel in Nigeria

The utilization of liquefied petroleum gas (LPG) as an alternative automobile fuel in Nigeria was studied, focusing on varying different blend ratios of propane and butane as an alternative fuel in a single-cylinder, four-stroke, and spark ignition (SI) engine. Ricardo WAVE, 1-Dimensional engine simulator was used to model the internal combustion engine where the different blend ratios of propane and butane (P100, P90B10, P80B20, P70B30, P60B40 and P50B50) were tested and compared with a gasoline engine operating under same conditions. From the simulation results for the different LPG blends, there was no significant difference in the engine performance and emissions, but when compared with pure gasoline, it was observed that the LPG showed improved engine performance and lower emissions. The engine power output in using the blends was 25% higher compared to using gasoline;CO emission was 50% less, UHC was 20% less while NOx at low speed was significantly lower.

The Use of Models to Evaluate Corrosion Effects on Mild Steel Heat Exchanger in Water and Mono Ethanol Amine (MEA)

Heat exchanger is an important equipment used in process industries for cooling and heating purposes. Its design configuration which involves the flow of cold and hot fluids within the exchanger subjects it to corrosion attack. The article utilized the principle of mass and energy conservation in the development of weight and temperature models to study the effect of corrosion on mild steel coupon inside the exchanger containing water and Mono ethanol amine (MEA). The models developed were resolved analytically using Laplace Transform and simulated using Excel as simulation tool and data obtained from experiment in the laboratory to obtain profiles of weight loss and temperature as a function of time. The weight loss and performance of mild steel under various corrosive conditions were examined which indicates the effect of corrosion on the mild steel heat exchanger in water and MEA media. The result shows that water is more corrosive than MEA at higher temperatures and at lower temperatures of 35°C and 1 atm, MEA has inhibitive properties than water as indicated by the weight loss result with time. The comparative analysis between the results obtained from the model simulation and experimental results shows that the result obtained from the model is more reliable and demonstrated better performance characteristics as it clearly shows mild steel heat exchanger experiences more corrosive effect in water medium than MEA at higher temperatures. And at lower temperatures, MEA becomes more inhibitive and less corrosive than water. The model simulation results correlate with various literatures and hence, it is valid for future referencing.

降低CO_(2)-原油最小混相压力的助混剂研究进展

CO_(2)驱最小混相压力(MMP)是衡量能否达到混相驱的重要参数,因此,为提高混相驱的应用率,迫切需要降低CO_(2)与原油间的最小混相压力,而油藏中加入助混剂是降低最小混相压力的有效手段。目前助混剂按照所含元素可分为碳氟、硅氧烷、碳氢(含氧)三大类。为了降低成本,提高助混效果,应在碳氟类助混剂加入碳氢类结构,向混合型的方向发展,而碳氢类助混剂具有良好的助混效果,并且有提升的空间,关键是找到合适的亲CO_(2)结构,计算机模拟是研究微观机理,辅助结构设计的重要手段。相比于碳氟类和硅氧烷类,碳氢类助混剂的成本较低,从成本的角度看最有应用潜力。目前影响助混剂规模化应用的主要因素是成本上的限制,未来推广应用需要石油与化工从业者的密切配合,重点介绍助混剂降低MMP的机理,总结了目前已有助混剂的结构以及助混效果,分析了助混效果的影响因素,展望了助混剂设计的发展方向。

Bulk and bubble-scale experimental studies of influence of nanoparticles on foam stability

Influence of silicon oxide(SiO_2) and aluminum oxide(Al_2O_3) nanoparticles on the stability of nanoparticles and sodium dodecyl sulfate(SDS) mixed solution foams was studied at bulk and bubble-scale. Foam apparent viscosity was also determined in Hele-Shaw cell In order to investigate the foam performance at static and dynamic conditions. Results show that the maximum adsorption of surfactant on the nanoparticles occurs at 3 wt% surfactant concentration. Foam stability increases while the foamability decreases with the increasing nanoparticle concentration. However, optimum nanoparticle concentration corresponding to maximum foam stability was obtained at 1.0 wt% nanoparticle concentration for the hydrophilic SiO_2/SDS and Al_2O_3/SDS foams. Foam performance was enhanced with increasing nanoparticles hydrophobicity. Air-foams were generally more stable than CO_2 foams.Foam apparent viscosity increased in the presence of nanoparticles from 20.34 mPa·s to 84.84 mPa·s while the film thickness increased from 27.5 μm to 136 μm. This study suggests that the static and dynamic stability of conventional foams could be improved with addition of appropriate concentration of nanoparticles into the surfactant solution. The nanoparticles improve foam stability by their adsorption and aggregation at the foam lamellae to increase film thickness and dilational viscoelasticity. This prevents liquid drainage and film thinning and improves foam stability both at the bulk and bubble scale.

Experimental investigation of enhancement of carbon dioxide foam stability, pore plugging, and oil recovery in the presence of silica nanoparticles

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.

锌镁比对Al-Zn-Mg牺牲阳极用于碳钢阴极保护的影响

研究不同锌镁质量比的Al-Zn-Mg合金作为牺牲阳极在3.5wt.%Na Cl溶液中用于碳钢阴极保护的性能。用纯Al、Zn和Mg金属通过铸造法制备Al-Zn-Mg阳极。采用光学显微镜、扫描电镜-能谱、X射线衍射和电化学等技术对样品进行表征和测试。结果表明,随着锌镁质量比的降低,α(Al)的晶粒尺寸和析出物的粒径减小,析出物的体积分数增大。当锌镁质量比大于4.0时,Al-Zn-Mg阳极具有最低的腐蚀速率;当锌镁质量比小于0.62时,Al-Zn-Mg阳极具有最高的腐蚀速率且对碳钢(AISI 1018)具有最好的阴极保护效果。与其他阳极相比,锌镁质量比为0.62的Al-Zn-Mg阳极具有多孔腐蚀产物。

Wettability alteration and oil recovery by spontaneous imbibition of smart water and surfactants into carbonates

Naturally fractured carbonate reservoirs have very low oil recovery efficiency owing to their wettability and tightness of matrix.However,smart water can enhance oil recovery by changing the wettability of the carbonate rock surface from oilwet to water-wet,and the addition of surfactants can also change surface wettability.In the present study,the effects of a solution of modified seawater with some surfactants,namely C12 TAB,SDS,and TritonX-100(TX-100),on the wettability of carbonate rock were investigated through contact angle measurements.Oil recovery was studied using spontaneous imbibition tests at 25,70,and 90°C,followed by thermal gravity analysis to measure the amount of adsorbed material on the carbonate surface.The results indicated that Ca2+,Mg2+,and SO42-.ions may alter the carbonate rock wettability from oil-wet to water-wet,with further water wettability obtained at higher concentrations of the ions in modified seawater.Removal of NaCl from the imbibing fluid resulted in a reduced contact angle and significantly enhanced oil recovery.Low oil recoveries were obtained with modified seawater at 25 and 70°C,but once the temperature was increased to 90°C,the oil recovery in the spontaneous imbibition experiment increased dramatically.Application of smart water with C12 TAB surfactant at 0.1 wt%changed the contact angle from 161°to 52°and enhanced oil recovery to 72%,while the presence of the anionic surfactant SDS at 0.1 wt%in the smart water increased oil recovery to 64.5%.The TGA analysis results indicated that the adsorbed materials on the carbonate surface were minimal for the solution containing seawater with C12 TAB at 0.1 wt%(SW+CTAB(0.1 wt%)).Based on the experimental results,a mechanism was proposed for wettability alteration of carbonate rocks using smart water with SDS and C12 TAB surfactants.

Temperature effect on performance of nanoparticle/surfactant flooding in enhanced heavy oil recovery

Recently,nanoparticles have been used along with surfactants for enhancing oil recovery.Although the recent studies show that oil recovery is enhanced using nanoparticle/surfactant solutions,some effective parameters and mechanisms involved in the oil recovery have not yet been investigated.Therefore,the temperature effect on the stability of nanoparticle/surfactant solutions and ultimate oil recovery has been studied in this work,and the optimal concentrations of both SiO2 nanoparticle and surfactant(sodium dodecyl sulfate)have been determined by the Central Composite Design method.In addition,the simultaneous effects of parameters and their interactions have been investigated.Study of the stability of the injected solutions indicates that the nanoparticle concentration is the most important factor affecting the solution stability.The surfactant makes the solution more stable if used in appropriate concentrations below the CMC.According to the micromodel flooding results,the most effective factor for enhancing oil recovery is temperature compared to the nanoparticle and surfactant concentrations.Therefore,in floodings with higher porous medium temperature,the oil viscosity reduction is considerable,and more oil is recovered.In addition,the surfactant concentration plays a more effective role in reservoirs with higher temperatures.In other words,at a surfactant concentration of 250 ppm,the ultimate oil recovery is improved about 20%with a temperature increase of 20°C.However,when the surfactant concentration is equal to 750 ppm,the temperature increase enhances the ultimate oil recovery by only about 7%.Finally,the nanoparticle and surfactant optimum concentrations determined by Design-Expert software were equal to 46 and 159 ppm,respectively.It is worthy to note that obtained results are validated by the confirmation test.

How much would silica nanoparticles enhance the performance of low-salinity water flooding?

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.

Performance comparison of novel chemical agents in improving oil recovery from tight sands through spontaneous imbibition

Tight sands are abundant in nanopores leading to a high capillary pressure and normally a low fluid injectivity.As such,spontaneous imbibition might be an effective mechanism for improving oil recovery from tight sands after fracturing.The chemical agents added to the injected water can alter the interfacial properties,which could help further enhance the oil recovery by spontaneous imbibition.This study explores the possibility of using novel chemicals to enhance oil recovery from tight sands via spontaneous imbibition.We experimentally examine the effects of more than ten different chemical agents on spontaneous imbibition,including a cationic surfactant(C12 TAB),two anionic surfactants(0242 and 0342),an ionic liquid(BMMIM BF4),a high pH solution(NaBO2),and a series of house-made deep eutectic solvents(DES3-7,9,11,and 14).The interfacial tensions(IFT)between oil phase and some chemical solutions are also determined.Experimental results indicate that both the ionic liquid and cationic surfactant used in this study are detrimental to spontaneous imbibition and decrease the oil recovery from tight sands,even though cationic surfactant significantly decreases the oil-water IFT while ionic liquid does not.The high pH NaBO2 solution does not demonstrate significant effect on oil recovery improvement and IFT reduction.The anionic surfactants(O242 and O342)are effective in enhancing oil recovery from tight sands through oil-water IFT reduction and emulsification effects.The DESs drive the rock surface to be more water-wet,and a specific formulation(DES9)leads to much improvement on oil recovery under counter-current imbibition condition.This preliminary study would provide some knowledge about how to optimize the selection of chemicals for improving oil recovery from tight reservoirs.

Effect of a synthesized anionic fluorinated surfactant on wettability alteration for chemical treatment of near-wellbore zone in carbonate gas condensate reservoirs

The pressure drop during production in the near-wellbore zone of gas condensate reservoirs causes condensate formation in this area.Condensate blockage in this area causes an additional pressure drop that weakens the effective parameters of production,such as permeability.Reservoir rock wettability alteration to gas-wet through chemical treatment is one of the solutions to produce these condensates and eliminate condensate blockage in the area.In this study,an anionic fluorinated surfactant was synthesized and used for chemical treatment and carbonate rock wettability alteration.The synthesized surfactant was characterized by Fourier transform infrared spectroscopy and thermogravimetric analysis.Then,using surface tension tests,its critical micelle concentration(CMC)was determined.Contact angle experiments on chemically treated sections with surfactant solutions and spontaneous imbibition were performed to investigate the wettability alteration.Surfactant adsorption on porous media was calculated using flooding.Finally,the surfactant foamability was investigated using a Ross-Miles foam generator.According to the results,the synthesized surfactant has suitable thermal stability for use in gas condensate reservoirs.A CMC of 3500 ppm was obtained for the surfactant based on the surface tension experiments.Contact angle experiments show the ability of the surfactant to chemical treatment and wettability alteration of carbonate rocks to gas-wet so that at the constant concentration of CMC and at 373 K,the contact angles at treatment times of 30,60,120 and 240 min were obtained 87.94°,93.50°,99.79°and 106.03°,respectively.However,this ability varies at different surfactant concentrations and temperatures.The foamability test also shows the suitable stability of the foam generated by the surfactant,and a foam half-life time of 13 min was obtained for the surfactant at CMC.

Stabilization of nickel nanoparticle suspensions with the aid of polymer and surfactant: static bottle tests and dynamic micromodel flow tests

Nickel nanoparticles can work as catalyst for the aquathermolysis reactions between water and heavy oil.A homogeneous and stable suspension is needed to carry the nickel nanoparticles into deeper reservoirs.This study conducts a detailed investigation on how to achieve stabilized nickel nanoparticle suspensions with the use of surfactant and polymer.To stabilize the nickel nanoparticle suspension,three surfactants including sodium dodecyl sulfate,cationic surfactant cetyltrimethylammonium bromide and polyoxyalkalene amine derivative(Hypermer) along with xanthan gum polymer were introduced into the nickel nanoparticle suspension.Static stability tests and zeta potential measurements were conducted to determine the polymer/surfactant recipes yielding the most stable nickel nanoparticle suspensions.Dynamic micromodel flow tests were also conducted on three suspensions to reveal how the nickel nanoparticles would travel and distribute in porous media.Test results showed that when the injection was initiated,most nickel nanoparticles were able to pass through the gaps between the sand grains and produced in the outlet of the micromodel;only a small number of the nickel nanoparticles were attached to the grain surface.A higher nickel concentration in the suspension may lead to agglomeration of nickel nanoparticles in porous media,while a lower concentration can mitigate this agglomeration.Moreover,clusters tended to form when the nickel nanoparticle suspension carried an electrical charge opposite to that of the porous media.Follow-up waterflood was initiated after the nanofluid injection.It was found that the waterflood could not flush away the nanoparticles that were remaining in the micromodel.

影响井眼稳定性的地质力学参数敏感性分析（英文）

井眼稳定性分析在石油工业中得到越来越多的关注。影响井筒稳定性的参数很多,包括地质力学性质(如弹性模量、轴向抗压强度和黏聚力)和作用力(如场应力和泥浆压力)。精确地确定这些参数不仅耗时、价格昂贵,有时甚至是不可能的。本文提供了一种系统的灵敏度分析法,以量化每个参数对井筒稳定性的影响程度。利用最大井壁位移作为研究井筒稳定性的一个稳定因子。采用Mohr模型的三维有限差分法进行数值模拟,用解析解对数值模型进行了验证。为了比较各种参数在灵敏度分析中的结果,提出了一种无量纲灵敏度因子。结果表明,根据岩石强度的不同,参数的重要程度是不同的。对于软岩石,最敏感的参数分别是最大水平应力、内摩擦角和地层压力,而对于强岩石,最敏感的参数分别是最大水平应力、泥浆压力和孔隙压力。本文也推算了每个参数的估计误差对井眼稳定性分析的误差的影响。

Experimental investigation into L-Arg and L-Cys eco-friendly surfactants in enhanced oil recovery by considering IFT reduction and wettability alteration

Surfactant flooding is an important technique used to improve oil recovery from mature oil reservoirs due to minimizing the interfacial tension(IFT)between oil and water and/or altering the rock wettability toward water-wet using various surfactant agents including cationic,anionic,non-ionic,and amphoteric varieties.In this study,two amino-acid based surfactants,named lauroyl arginine(L-Arg)and lauroyl cysteine(L-Cys),were synthesized and used to reduce the IFT of oil–water systems and alter the wettability of carbonate rocks,thus improving oil recovery from oil-wet carbonate reservoirs.The synthesized surfactants were characterized using Fourier transform infrared spectroscopy and nuclear magnetic resonance analyses,and the critical micelle concentration(CMC)of surfactant solutions was determined using conductivity,pH,and turbidity techniques.Experimental results showed that the CMCs of L-Arg and L-Cys solutions were 2000 and 4500 ppm,respectively.It was found that using L-Arg and L-Cys solutions at their CMCs,the IFT and contact angle were reduced from 34.5 to 18.0 and15.4 mN/m,and from 144°to 78°and 75°,respectively.Thus,the L-Arg and L-Cys solutions enabled approximately 11.9%and 8.9%additional recovery of OOIP(original oil in place).It was identified that both amino-acid surfactants can be used to improve oil recovery due to their desirable effects on the EOR mechanisms at their CMC ranges.

Optimization of Drilling Parameters by Analysis of Formation Strength Properties with Utilization of Mechanical Specific Energy

By increasing the daily needs of human energy, human manipulation of natural energy sources is expanded and encouraged the human society to developing science, knowledge and technology. Mechanical specific energy required energy for drilling the unit of formation volume. This parameter can be used for functional analysis of drilling, drilling bit optimization and investigating of instability has been made during drilling operations. This parameter can be used for decreasing of drilling costs by increasing drilling speed, optimized the useful life of the drilling bit and determine the right time to replace the drilling bit, and in some cases reduced to a minimum amount. In South Pars field in Iran, many wells have been drilled;however detailed statistics processes hadn’t done for optimizing drilling parameters and their impact on mechanical specific energy. By results of these studies, we can analyze performance and drilling parameters such as weight on drilling bit, rotational speed, penetration rate, etc. In the most investigated cases, mechanical specific energy at the final period time of drilling on each wells has been increased gradually due to the speed movement reduction. Although by investigating middle formations in section of 12.25 inch, all existing wells on a platform in one of the phases of Iran’s South Pars field are being studied, which contains formations such as Hith, Surmeh, Neyriz, Dashtak and Kangan. Studies were done in two parts. In the first part, the range of optimized drilling parameters that is increasing drilling speed and reducing the required amount of energy for drilling formation. This process by investigating mechanical specific energy and its relationship with uniaxial compressive strength in five studied formation have been presented. In the second part, correlations to predict the mechanical specific energy in this area by statistical methods by SPSS software, presented and reviewed. Then, by the most appropriate relationship, the most influential drilling parameters on mechanical specific energy have been set. However, for drilling the next wells in this area drilling parameters with the most priority influences on mechanical specific energy, proposed in the optimum range, will be recommended.

Nanohybrid membrane in algal-membrane photoreactor: Microalgae cultivation and wastewater polishing

Microalgae cultivation has gained tremendous attention in recent years due to its great potential in green biofuel production and wastewater treatment application. Membrane technology is a great solution in separating the microalgae biomass while producing high quality of permeate for recycling. The main objective of this study was to investigate the filtration performance of Ag/GO-PVDF(silver/graphene oxide-polyvinylidene fluoride) membrane in an algalmembrane photoreactor(A-MPR) by benchmarking with a commercial PVDF(com-PVDF) membrane. In this study, Chlorella vulgaris microalgae was cultivated in synthetic wastewater in an A-MPR for ammoniacal-nitrogen and phosphorus recovery and the wastewater was further filtered using Ag/GO-PVDF and com-PVDF membranes to obtain high quality water. Spectrophotometer was used to analyze the chemical oxidation demand(COD), ammoniacal nitrogen(NH3-N) and phosphate(PO43-). The concentration of proteins and carbohydrates was measured using Bradford method and phenol-sulfuric acid method, respectively. The COD of the synthetic wastewater was reduced from(180.5 ± 5.6) ppm to(82 ± 2.6) ppm due to nutrient uptake by microalgae. Then, the Ag/GO-PVDF membrane was used to further purify the microalgae cultivated wastewater, resulting in a low COD permeate of(31 ± 4.6) ppm. The high removal rate of proteins(100%) and carbohydrates(86.6%) as the major foulant in microalgae filtration, with low membrane fouling propensity of Ag/GO-PVDF membrane is advantageous for the sustainable development of the microalgae production. Hence, the integrated A-MPR system is highly recommended as a promising approach for microalgae cultivation and wastewater polishing treatment.

Optimization and evaluation of reduced graphene oxide hydrogel composite as a demulsifier for heavy crude oil-in-water emulsion

The rising production of produced water from oilfields had been proven to bring detrimental environmental effects.In this study,an efficient,recyclable,and environmental-friendly reduced graphene oxide immobilizedκ-Carrageenan hydrogel composite(κCaGO)was fabricated as an alternative sorbent for crude oil-in-water demulsification.Polyethyleneimine(PEI)was employed to form a stable hydrogel composite.The conditions for the immobilization of graphene oxide(GO)on PEI-modifiedκ-Carrageenan(κC)beads were optimized appropriately.An immobilization yield of 77%was attained at 2%PEI,2 h immobilization activation time,and pH 6.5.Moreover,the synthesizedκCaGO is capable of demulsification with an average demulsification efficiency of 70%.It was found that the demulsification efficiency increases with salinity andκCaGO dosage,and it deteriorates under alkaline condition.These phenomena can be attributed to the interfacial interactions betweenκCaGO and the emulsion.Furthermore,theκCaGO can be recycled to use for up to six cycles without significant leaching and degradation.As such,the synthesizedκCaGO could be further developed as a potential sorbent substitute for the separation of crude oil from produced water.