Using biosurfactant producing bacteria isolated from an Iranian oil field for application in microbial enhanced oil recovery

Microbial enhanced oil recovery (MEOR) is a useful technique to improve oil recovery from depleted oil reservoirs beyond primary and secondary recovery operations using bacteria and their metabolites. In the present study, the biosurfactant production potential of Bacillus licheniformis microorganisms that were isolated from oil samples of Zilaei reservoir in the southwest of Iran was explored under extreme conditions. Growth media with different temperatures of 40, 50, 60, and 70°C; salinities of 1, 3, 5, and 7 wt%; and yeast extract concentrations of 0.5, 1, 1.5, and 2 g/L were used to find the optimum growth conditions. The results demonstrated that bacteria grown in a mineral salt solution with temperature of 50°C, salinity of 1 wt% and yeast extract concentration of 1 g/L has the highest growth rate and therefore, these conditions are the optimum conditions for growing the introduced bacterium. This isolate was selected as the higher biosurfactant producer. The obtained biosurfactants by bacteria isolated in a medium with these conditions could reduce the interfacial tension of crude oil/water system from 36.8 to 0.93 mN/m and surface tension of water from 72 to 23.8 mN/m. The results of the core flooding tests showed that the tertiary oil recovery efficiency due to the injection of microorganisms was 13.7% of original oil in place and bacteria could reduce the oil viscosity by 41.242% at optimum conditions. Based on these results, the isolated microorganism is a promising candidate for the development of microbial oil recovery processes.     

纳米流体强化驱油机理研究进展

纳米流体强化驱油技术对于降低石油开采成本和提高石油采收率具有十分重要的意义.关于纳米流体强化驱油机理的研究,近年来取得了一系列重要成果.本文重点阐述了关于纳米流体驱油机理的相关基础研究工作,在综合不同学术观点和研究成果的基础上归纳了纳米流体强化驱油的四种机理,据此指出在结构分离压力、岩石润湿性改变和油水界面张力降低的共...     

A lysine amino acid-based surfactant: Application in enhanced oil recovery

Surfactants can play major role in increasing oil recovery factor through interfacial tension reduction. In the present study, a new synthetic method was used to prepare (S)-2-amino-6-dodecanamidohexanoic acid, an amino acid–based surfactant then it was applied as an oil recovery agent for the first time. The structure of this surfactant was studied using FTIR and ¹H NMR spectroscopy. The critical micelle concentration was found to be value is 0.4–0.5 wt% using surfactant solution conductivity, pH, and IFT methods. A 56.50% reduction of IFT was recorded using this environmentally friendly surfactant.     

脂肽生物表面活性剂在微生物采油中的应用

对从大庆油田分离到的一株枯草芽孢杆菌(Bacillus subtilis)ZW-3代谢的脂肽生物表面活性剂的理化性质(CMC值、乳化活性、对温度、矿化度的稳定性、降低油水界面张力能力)进行了测定,同时进行了物理模拟实验。研究结果表明,该脂肽表面活性剂具有优良的乳化和降低油水界面张力的能力,并可以适应油藏中复杂的环境,可提高采收率9.2%。在微生物采油中具有较好的应用前景。     

气润湿反转提高采收率实验研究

注气开采是三次采油的一种重要开发方式,在气驱水的过程中,气润湿反转可以使毛细管压力由气驱阻力变为动力,从而提高气驱油效率.用N2和CO2做气驱水实验,研究气润湿反转对提高采收率的影响.实验所用岩心为长庆油田的低渗透率岩心,所用气润湿反转剂属阳离子型氟化物.对气润湿反转前后的岩心做气驱水实验,绘出气润湿反转前后水的采出程...     

纳米二氧化硅在三次采油中的应用研究

采用溶胶-凝胶法制备了纳米二氧化硅,对其进行了有机改性。将纳米二氧化硅、改性纳米二氧化硅分别与油田驱油中广泛应用的石油磺酸盐组成复合体系,采用TX-500界面张力仪测定了该复合体系降低油水界面张力的能力。研究结果表明:表面活性剂总浓度为1%时,石油磺酸盐、纳米二氧化硅-石油磺酸盐复合体系能使油水界面张力降低至0.01mN/m左右,改性纳米二氧化硅-石油磺酸盐复合体系能使油水界面张力降低至3.37×10^-3mN/m左右。改性纳米二氧化硅加入石油磺酸盐显著地降低了油水界面张力,从而提高了原油的采收率。     

The preparation of an amino acid-based surfactant and its potential application as an EOR agent

Most of the synthetic surfactants investigated with the aim of enhanced chemically oil recovery in the literature have environmental drawbacks. In this work, application of an environmentally-friendly synthetic surfactant as an enhanced oil recovery agent is introduced by measuring interfacial tension of water–kerosene systems and wettability alteration of carbonate pellets. For this purpose, an amino acid-based surfactant was initially synthesized using a new synthetic approach which was subsequently confirmed by spectra of Fourier transform infrared and Proton nuclear magnetic resonance. Results showed a value of critical micelle concentration in the range of 9000–9100 ppm for this surfactant. Results also demonstrated a decrease of 38.53% in water–kerosene system interfacial tension and a 17.76% reduction in oil-wetness of the carbonate pellets.     

双子(Gemini)表面活性剂合成及性能评价

研究合成了一种阴离子型双醚双苯磺酸盐Gemini表面活性剂,该表面活性剂可在无碱,质量浓度为35 mg·L-1条件下,将油水界面张力降至1.2×10-3 mN·m-1的超低水平;可有效改变岩石表面润湿性,可将亲油表面改变为弱亲油表面,可将亲水表面改变为弱亲水表面;利用该Gemini表面活性剂配制的三元复合驱(ASP)驱油体系相比常规驱油体系,表现出更高的驱替效率.     

Application of Biosurfactants to Wettability Alteration and IFT Reduction in Enhanced Oil Recovery From Oil–Wet Carbonates

To obtain potentially applicable microorganisms to an effective in situ microbial enhanced oil recovery operation, bacteria that were compatible with the harsh conditions of a petroleum reservoir were isolated from a crude oil sample. The application of an oil spreading technique showed that all of the isolates were capable of producing biosurfactants from both the glucose and crude oil as carbon sources. The secreted biosurfactants could at least reduce the surface tension 20 mN/m and for one of the isolates; the surface tension value dropped below 40 mN/m. In addition, the contact angle measurements revealed that the produced biosurfactants could effectively alter the wettability of the oil saturated rock samples. At last, the effect of isolates and their biosurfactants on improving oil production from oil saturated rock samples was investigated. It was observed that the presence of bacteria in the system could increase the amount of produced oil in comparison with the case where cell free biosurfactants were utilized.     

表面活性剂驱乳化作用对提高采收率的影响

表面活性剂驱是高温高盐油藏提高原油采收率的重要技术措施,但其乳化作用对提高采收率的影响并未受到足够重视。为了分析濮城油田高温高盐油藏表面活性剂驱乳化作用对提高采收率的影响,通过对表面活性剂降低油水界面张力的性能评价,优选出2种表面活性剂YD-G1和SHY-1,用高矿化度的濮城油田现场注入水配制质量分数为0.3%的溶液,将其放入120℃恒温箱30 d后,油水界面张力仍能达到10-3mN/m的超低数量级,表明2种表面活性剂均具有良好的耐温抗盐性能。将2种表面活性剂与濮城油田脱水脱气原油配制成乳状液,在同等质量分数下YD-G1乳状液的析水率低于SHY-1,且液滴的平均粒径也更小,表明YD-G1溶液比SHY-1溶液的乳化能力强。驱油实验结果表明,YD-G1溶液比SHY-1溶液的驱油效果更佳,表明乳化作用是提高采收率的关键因素之一。通过室内实验优化设计,确定YD-G1溶液的最佳注入量为0.5倍孔隙体积,最佳注入质量分数为0.3%。     

聚/表二元复合驱提高普通稠油水驱后残余油采收率的研究

采用椰油脂肪酸二乙醇酰胺型烷醇酰胺(6501)与部分水解聚丙烯酰胺(HPAM)组成二元复合驱体系,利用旋转滴法测定了该二元复合驱体系的耐温、抗盐、抗二价离子等性能,通过人造岩心物模实验和微观驱油实验分别评价了该体系的驱油效果。实验结果表明,0.1%(w)HPAM+0.3%(w)6501二元复合驱体系在40~80℃、矿化度1 000~13 000 mg/L、Ca~(2+)含量50~350 mg/L范围内的油水界面张力在10~(-3)~10~(-2) m N/m间保持稳定;人造岩心物模实验和微观驱油实验结果均显示,水驱后注入聚合物驱或二元复合驱时,二元复合驱体系较单独的聚合物驱可进一步提高采收率。     

The Application of Nanofluids for Enhanced Oil Recovery: Effects on Interfacial Tension and Coreflooding Process

Most oil reservoirs around the world are experiencing their second half of life. Hence, the necessity of appropriate enhanced oil recovery (EOR) method as a more efficient technology gets further importance. Nanotechnology is an advanced technology that has proved its potential to enhance oil recovery. In this study, some selected types of nanoparticles were used, which were aluminum oxide, iron oxide, and silicon oxide treated by silane, as EOR agents during different flooding scenarios and EOR experiments under surface conditions. For the first time, the application of propanol as a dispersing agent of nanoparticles and EOR agent in the formation was investigated by this research work. In order to examine the recovery mechanisms of nanofluids, interfacial tension (IFT), and contact angle measurements between different concentrations of nanofluids and crude oil were measured. Then, several coreflood experiments were conducted to investigate their impacts directly on recoveries. The experiment results show that the nanofluids can decrease the IFT between water and oil phases and make the solid surface more neutral wet. Results indicate that aluminum oxide and silicon oxide treated by silane are good agents for enhanced oil recovery, while silicon one changes rock wettability more in addition to reduction of interfacial tension between oil and water. According to the results the future expectation is that these nanoparticles with their dispersing agent could mobilize more oil in the pore network at field scale to improve oil recovery.     

纳米技术在提高原油采收率方面的应用新进展

文中对纳米技术在提高原油采收率方面的应用作了介绍和评述,涉及原理、制备、性能、工艺、现场应用效果等方面。其中。较详细地介绍了改进的纳米粒分散体系和纳米乳液的作用机理及提高采收率的效果,适合复杂地层和苛刻环境的纳米硅凝胶、纳米聚合物微球封堵技术．以及纳米复合压裂增产技术等方面的基础理论研究和应用情况。     

Interfacial activity of alkyl hydroxyl sulfobetaine against crude oil

To study the interfacial activities of zwitterionic surfactant against crude oil, four alkyl hydroxyl sulfobetaines were synthesized. The effects of surfactant structure, concentration, salinity of formation water, and crude oil composition on interfacial activities were discussed. It shows that the octadecyl hydroxyl sulfobetaine can achieve ultralow interfacial tension at the concentrations no less than 0.001%, exhibiting a good interfacial activity and a very strong antidilution ability. The salinity of formation water has no obvious effect on lowering the interfacial tension and the polar component in crude oil is very crucial for the production of ultralow interfacial tension. This work is important for enhanced oil recovery.     

Microemulsion flooding for enhanced oil recovery

Petroleum recovery methods basically consist of fluid injection aiming to displace the oil out of the rock pores. Among the methods used in enhanced oil recovery, chemical methods, which may involve microemulsion flooding, are cited. In this work, injection assays have been carried out with two types of microemulsion: one was prepared with a commercial surfactant (MCS) and another contained a surfactant synthesized in laboratory (MLS). The experiments basically consisted of the injection of fluids into cylindrical plug samples from the Assu Formation (RN, Brazil). During the microemulsion flooding, samples were collected as a function of time and the mass of oil recovered by the microemulsion was determined. From the results obtained, one could conclude that the use of microemulsion prepared with the commercial MCS allowed for recovery indices as high as 87.5%, whilst the use of the MLS microemulsion permitted recovery indices as high as 78.7%. This was mainly due to the difference in viscosity between the two microemulsions used.     

The Synthesis and Performance of Sodium Methyl Ester Sulfonate for Enhanced Oil Recovery

Abstract

Due to the high cost of surfactant production caused by petrochemical feedstocks, much attention has been given to nonedible vegetable oils as an alternative source of feedstock. A new nonedible oil-derived surfactant based on the Jatropha plant is synthesized. A single-step route was used for synthesizing sodium methyl ester sulfonate (SMES) for enhanced oil recovery application. The performance of the resultant surfactant was studied by measuring the interfacial tension between the surfactant solution and crude oil and its thermal stability at reservoir temperature. The SMES showed a good surface activity, reducing the interfacial tension between the surfactant solution and crude oil from 18.4 to 3.92 mN/m. The thermal analysis of SMES indicates that 26.1% weight loss was observed from 70°C to 500°C. The advantage of the new SMES is the low cost of production, which makes it a promising surfactant for enhanced oil recovery application and other uses.     

Effect of wettability on oil recovery and breakthrough time for immiscible gas flooding

The effect of wettability on oil recovery at higher water saturation is still not fully understood, especially in the case of mixed wettability. This study was conducted to examine the effects of wettability on oil recovery and breakthrough time through experiments for two wettability conditions (water-wet and mixed-wet) and three water saturations (20%, 40%, and 60%). Clashach sandstone core with a porosity of 12.8% and a permeability of 75 md was utilized as the porous media. Immiscible gas flooding was performed by injecting nitrogen gas into the core at room temperature and pressure. The results showed 54.3% and 48.8% of the initial oil in place (IOIP) as the ultimate oil recovery at 40% water saturation from mixed-wet core and water-wet core respectively. In contrast, the water-wet core displayed better results (32.6% of the IOIP) in terms of breakthrough time compared to the results of water-wet core (10.6% of the IOIP) at the same water saturation. In conclusion, oil recovery was found highly dependent on water saturation while breakthrough time was mainly affected by the wettability of the cores.     

致密油藏提高采收率技术瓶颈与发展策略

致密油藏正在成为全球油气资源勘探开发热点领域。致密油藏开发效益在一定程度上反映了一个国家当代石油勘探开发的技术能力和水平。总体来看,全球范围内致密油藏平均采收率为5%～10%,远低于常规油藏。中国致密油藏地质特征复杂,其开发关键技术尚处于突破前的准备阶段,美国相对成熟的致密油藏开发配套技术不能直接照搬应用。针对中国致密油藏采收率低和相关配套技术发展滞后的现状,概述了致密油藏开发和提高采收率的主要关键技术,剖析了待解决的理论认识与技术瓶颈等问题。分析认为,推行致密油藏开发地质工程、保护改造、增渗增能、洗油驱油"多维一体化"技术思路,协同大型水力压裂储层改造,实施界面修饰注水和储层原油氧化实现有效增能增注,开展多环节、多尺度、多场综合调控油水流动行为,显著增强油水流动能力,将是提高致密油藏采收率及开发综合效益的新途径。     

油水乳化能力对油膜驱替的影响

为深化油膜驱替机理认识,开展油膜驱替实验。以综合反映乳化速度和乳化量的乳化系数量化表征油水乳化能力。针对实验用低黏和中黏原油,筛选出具有强乳化能力-超低界面张力、强乳化能力-低界面张力和弱乳化能力-超低界面张力3种不同性质的驱油剂,并进行玻璃棒束油膜驱替实验。实验结果表明,对于低黏原油,乳化系数分别为0.667和0.706的强乳化能力驱油剂,不论其界面张力是否达到超低,其驱替效率都约为90%,而乳化系数为0.244的弱乳化能力-超低界面张力驱油剂的驱替效率不足70%;对于中黏原油,乳化系数分别为0.534和0.602的强乳化能力驱油剂,不论其界面张力是否达到超低,其驱替效率都约为83%,而乳化系数为0.258的弱乳化能力-超低界面张力驱油剂的驱替效率不足65%。研究结果表明,油水乳化能力是对油膜驱替起决定作用的性能指标。