Detection and Reuse of the Produced Chemicals in Chemical Enhanced Oil Recovery Operations

The alkaline-surfactant-polymer (ASP) floods have been increasingly applied in the oil fields because of their high ultimate oil recovery. However, a major technical challenge is how to reduce the amount and the cost of chemicals used so that ASP floods can become cost-effective as well. On the other hand, field applications show that the chemical concentrations remain relatively high in the produced liquids of ASP floods. Therefore, successful detection and reuse of these produced chemicals can substantially reduce their capital cost and environmental impact. In this article, several experimental methods are developed to detect each chemical and quantify its concentration in the produced liquids. Also re-injection of the produced chemicals is conducted to further enhance oil recovery. First, the respective interactions of alkali, surfactant, and polymer with the oil-brine-sand system are studied. Second, the interfacial tension (IFT) is measured as a function of alkaline concentration by using the axisymmetric drop shape analysis technique for the pendant drop case. In addition, the synergistic effects of alkali and surfactant on reducing the IFT are studied. Third, coreflood tests are performed for alkaline, surfactant, alkaline-surfactant, polymer, and ASP floods to determine their respective tertiary oil recovery. Hence, how each chemical contributes to enhanced oil recovery is better understood. Fourth, the produced chemical concentrations are measured and compared with their injected concentrations to determine the potential of reusing these chemicals in practice. Finally, the follow-up coreflood tests are conducted by re-injecting the produced liquids into a new sand pack or Berea core. The re-injection coreflood test results show that the produced chemicals can be reused to effectively enhance oil recovery.     

Experimental Investigation of Matricaria chamomilla Extract Effect on Oil-Water Interfacial Tension: Usable for Chemical Enhanced Oil Recovery

Recently, natural surfactants had been studied for chemical enhanced oil recovery as opposite to synthetic surfactants due to environmental problems associated with synthetic surfactants. In this study a new plant based natural surfactant, Matricaria chamomilla, is introduced. For this purpose, the interfacial tension values between natural surfactant solution and oil are measured by using the pendant drop method. The results show that Matricaria chamomilla decreased the oil-water interfacial tension values from 30.63 to 12.57 mN/m. Results confirm surface chemical activity of Matricaria chamomilla in comparison with other natural surfactants.     

以糠醛抽出油为原料制备三次采油用表面活性剂

以糠醛抽出油为原料,通过磺化制备了一种表面活性剂KOCS。界面张力测试结果表明,在强碱NaOH存在的条件下,当KOVS含量为0．2％,碱含量在0．6％～1．4％范围时,KOCS体系与大庆四厂原油可形成超低界面张力(-10^-3mN／m)。在无碱条件下,KOCS表面活性剂单独用于大港油田枣园1256断块原油时,油-水界面张力可达到10^-2mN／m。KOCS能够满足不同油田化学驱对表面活性剂的要求。     

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.     

Evaluation of Surfactants for the Cost Effective Enhanced Oil Recovery of Assam Crude Oil Fields

Based on a hierarchial methodology, the article presents the comparative efficacy of Vim commercial detergent for the purpose of surfactant enhanced oil recovery of Assam crude oil in Indian reservoirs. Suitable technical and economic indices were defined to explore the economic competence with other surfactants such as sodium dodecyl benzene sulfonate and sodium dodecyl sulfonate. It was evaluated that the detergent formulation provided the following performance characteristics: I_C = 13.43 mN/m.g/L surfactant solution, surfactant sustainability index = 3.88 × 10^?3 mN/m.$/L surfactant solution, cost ratio = 0.32 ? 0.52 $ surfactant/$ crude oil recovered and 14.7–15.1% tertiary recovery with respect to original oil in place. Further ultralow interfacial tension formulations were also achievable with the commercial detergent.     

ASP体系在大庆二类油层中的色谱分离现象及其对采收率的影响

ASP体系在二类油层中运移不同距离时,体系的黏度和及其与原油间的界面张力等均会发生变化。本实验采用不同长度的人造岩心(10、20、30、60和80 cm)来模拟ASP体系在油藏中的运移距离,通过测定各组实验产出液的黏度及其与原油间界面张力,分析ASP体系运移不同距离时体系性能的变化及其对采收率的影响。实验结果表明,随着ASP驱油剂运移距离的增大,复合驱采收率逐渐降低,且在近井地带附近采收率降低的幅度较大。复合驱采收率受复合体系的黏度和其与原油界面张力影响,在0~30 cm运移范围内,由于超低界面张力和较强流度控制能力的综合作用,驱油剂在油藏中的波及体积和驱油效率较大,复合驱采收率和最终采收率较高;当运移距离大于30 cm时,由于界面张力值迅速升高,其对采收率的贡献较小,此时体系的黏度在驱油过程中起着主导作用;复合驱采收率随着驱油剂相对注入量的增大而增加,适当地增大ASP驱油剂的相对注入量可有效的提高大庆二类油层的采收率。     

A New Type of Surfactant for Enhanced Oil Recovery

abstract

Most naturally fractured reservoir rocks are mixed to oil wet and do not imbibe the injected water, which translates into low-efficiency waterflood recovery. To enhance the spontaneous imbibition process, a low concentration of surfactants is dissolved into the injected water to induce wettability alteration of the reservoir rock by changing the wettability of the rock toward a more water-wet state. Zizyphus spina-christi leaves, which are grown in the Middle East, produce a special surfactant called saponin. This surfactant can be used for chemical flooding in Iranian oil fields due to its low cost and availability. Saponin was extracted from leaves using a spray-drying method and the interfacial tension (IFT) between saponin–water–oil was determined. For interfacial tension measurements the pendant drop method was used. A typical pendant drop apparatus is presented in this article. The algorithms used to infer interfacial tension from the geometrical profile of the pendant drop are described in detail; in particular, a new method for evaluation of the value of the radius at the apex of the drop, necessary for calculation of interfacial tension, is presented. Saponin caused a reduction in interfacial tension from 48 to 9 dyn/cm, which can be decreased to ultralow IFT by the addition of salt and alcohol. According to the results, saponin can be used as a surface-active agent for enhanced oil recovery.     

微生物采油技术与油田化学剂

微生物采油技术研究和现场应用范围不断扩大，前景良好。本专论叙述了微生物采油与油田化学剂之间的关系，共分6个部分；①影响微生物采油的油田化学剂简介；②化学剂对微生物的不良作用，包括对微生物呼吸作用，蛋白质、核酸、结构大分子合成及细胞壁功能的直接影响和通过改变环境介质渗透压、氧化还原位，pH值对微生物生长的间接影响；③化学剂影响的评价，包括测定最低影响浓度、作用持续时间，并考虑化学剂在地层内的变化；④化学剂不利影响的消除，包括筛选具有抗某种化学剂的菌种，培育具有特定性能的菌种，如可用于聚合物驱后油田的可降解聚合物的菌种。⑤微生物采油需要的化学剂：碳源、氮源、磷源等，利用内源微生物的驱油技术。⑥简短结论。     

用钻特殊井方法提高采收率

尽管三次采油过程的各种提高采收率技术在经济、合理、最大限度的开采石油方面发挥了重要作用,但由于许多技术目前尚处于部分工业运用及实验室研究阶段,加上许多技术本身的局限性和油藏的复杂性,导致其效果并不理想。随着钻井技术的进步,水平井、侧钻水平井、分支井、大位移井等特殊井在提高石油采收率上的贡献日见报道,但是从观念认识上,往往没有把这些钻井方法列入提高石油采收率的技术之列。文中在讨论目前各种提高采收率技术的优点和不足之处的基础上,提出了对现有采收率技术不适用的油藏而言,用特殊井提高采收率比现有各种提高采收率技术优越,并阐述了钻井方法提高采收率技术的优点及其前景。     

Design of Alkaline/Surfactant/Polymer (ASP) Slug and its use in Enhanced Oil Recovery

Abstract

Studies have been done to design an optimum composition of alkali/surfactant/polymer (ASP) slug and its application in flooding to increase the additional recovery of oil. A very low concentration of alkali and surfactant is used to achieve ultra-low interfacial tension between the trapped oil and the injection water, and polymer is used to increase the viscosity of the injection water for mobility control. Based on the experimental results of physico-chemical properties of polymer, surfactant, and alkali and their mutual interaction in solution, an ASP slug of composition SDS: 0.1 wt%, SDBS: 0.075 wt%, polyacrylamide: 2,000 ppm, and NaOH: 0.7 wt% has been recommended for flooding. Two sets of core-flooding experiments have been conducted using the designed ASP slug in a tri-axial core holder to measure the additional recovery of oil. The average additional oil recovery over conventional water flooding was found to be more than 20% of the original oil in place (OOIP).     

An Environment-Friendly Alkaline Solution for Enhanced Oil Recovery

Abstract

The injection of alkali and alkali/polymer solutions is a well-known enhanced oil recovery technique. This article demonstrates how wood ash can be used as a source of low cost alkali instead of synthetic alkali that is also environmentally friendly. From the experimental studies, it is found that the pH value of 6% wood ash extracted solution is very close to the pH value of 0.5% synthetic NaOH or of 0.75% Na₂SiO₃ solution. A preliminary microscopic study of oil/oil droplets interaction in natural alkaline solution was carried out in order to understand the oil/water interface changes with time and its effect on oil/oil droplet coalescence. Also, interfacial tension (IFT) was measured for both synthetic and natural alkaline solutions. The IFT values in the presence of acidic crude oil show comparable results.     

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.     

复合驱中界面张力数量级与提高采收率的关系研究

文章分析了表面活性剂/聚合物二元复合驱和碱/表面活性剂/聚合物三元复合驱驱油指标(超低界面张力必须达到10-3mN/m)理论的缺陷;在大量岩心试验的基础上,比较了不同界面张力下的采收率值,认为平衡界面张力为10-3mN/m不是表面活性剂驱油及复合驱的必要条件,平衡界面张力为10-2mN/m时也能达到与前者同样的驱油效果;并且只要瞬时界面张力达到10-3mN/m,也能达到较好的驱油效果,从而为表面活性剂复合驱的广泛应用提供了实验基础。     

菌种基因检测技术及其在微生物采油中的应用

针对吉林油田微生物采油矿场试验效果波动性大、成功与失败原因不清、菌种在油藏的适应能力、增产效果及应用潜力无法确定等实际问题,开发建立了菌种基因扩增及其酶切多态性分析基因检测技术。概述了聚合酶链式反应的特点、作用和基本原理,目的菌种基因检测的原理、步骤和方法,矿场跟踪检测的具体试验过程。通过目的菌种基因跟踪检测的系统分析,说明了影响和制约矿场试验各环节的主要技术因素,为考察研究目的菌种的种属、浓度、生存竞争能力、地下运移能力、采油性能等试验研究,把握试验进程,调整其工艺,优化方案设计提供了有效的技术手段,也为检测和评价商业菌种的技术质量提供了可靠的依据。     

石油磺酸盐表面活性剂在三次采油中的应用

根据国内外文献中石油磺酸盐合成和应用实例,对石油磺酸盐表面活性剂的制备、驱油机理、复配体系、国内外矿场试验的情况和存在的问题进行了概述,并对今后的发展方向及应用前景进行了展望。     

高浓度三元复合体系增油效果及其作用机理研究

本文分析了高浓度三元复合驱增油效果的影响因素和经济效益。结果表明,在驱油剂费用相同时,0.12%高分聚合物驱、0.3%非离子表面活性剂/0.25%超高分聚合物二元复合驱、1.2%碱/0.3%磺酸盐/0.25%超高分聚合物三元复合驱的采收率增幅分别为19.6%、15.9%、13.7%。在高浓度三元复合体系黏度相同的条件下,体系界面张力由8.10×10^-1降至5.73×10^-3 mN/m,采收率增幅由23.4%增至27.7%。当三元复合驱黏度由36.8增至134.4 mPa·s时,采收率增幅由18.5%增至32.9%;当段塞尺寸由0.095增至0.475 PV时,采收率增幅由15.6%增至30.7%,但采收率增幅差值逐渐减小。在药剂费用相同的条件下,“聚合物前置段塞+三元主段塞+三元副段塞+聚合物保护段塞”组合的采收率增幅较大（33.8%）。从技术和经济效益方面考虑,推荐三元复合体系聚合物浓度范围为0.2%～0.25%,段塞尺寸为0.380～0.475 PV。对于非均质比较严重的油藏,与驱油剂洗油作用相比,其扩大波及体积作用对采收率的贡献较大。     

Microemulsions in Enhanced Oil Recovery: A Review

Abstract

Microemulsions have recently made advances in enhanced oil recovery processes in which chemicals, especially surfactants, are used to recover the oil from natural oil reservoirs. This technique relies on the knowledge of interfacial properties among oil, water, and solid rock reservoirs in the occasional presence of natural gas under extreme conditions. Surfactant-based chemical systems have been reported in many academic studies and their technological implementation is a potential candidate in enhanced oil recovery (EOR) activities. For instance, it was determined that a mobilized buffer (polymer) with viscosity either equal to or greater than the mobilized oil enhanced the recovery efficiency considerably. However, EOR based on chemicals like alkaline–surfactant–polymer (ASP) is a complex technology requiring a high level of expertise for its industrial implementation. The surfactant–polymer interaction is a rapidly growing research area for efficient oil recovery by improving slug integrity, adsorption, and mobility control. This review article evaluates the injecting fluid system to highlight some recent advances in the use of chemicals in EOR, especially with microemulsions. It further reveals the current status and future outlook for EOR technology in oil fields and describes the opportunities for strategic utilities and load growth in petroleum industry.     

Pre-prepared Microemulsion Flooding in Enhanced Oil Recovery: A Review

It is evident that one of the important applications of microemulsions is in enhanced oil recovery (EOR) process due to its unique properties such as ultra-low interfacial tension. The injection of microemulsion slug reduces the interfacial tension between the crude oil and reservoir brine, which leads to mobilization of substantial fraction of residual oil. In general microemulsion flooding is classified into two distinct categories, pre-prepared and in situ prepared, depending on its preparation method. The authors present a detailed discussion of microemulsion preparation and summarizes major articles on pre-prepared microemulsion flooding in EOR processes. Their review opens new horizons for the future researches on pre-prepared microemulsion flooding in EOR processes by organizing the literature data and comparing them.     

Experimental Investigation of Viscous Surfactant Based Enhanced Oil Recovery

Crude terephthalic acid (CTA) as a chemical compound is used for flooding here as an alternative to the traditional hydrolyzed polyacrylamide (HPAM) because of its availability and economical aspects and higher efficiency. Crude oil samples from an Iranian oil field were used during the flooding tests. Sand packed models using two different sizes of sand mainly 50 and 100 meshes were employed in this investigation. A comparison between water flooding and CTA flooding as a secondary oil recovery process revealed that the oil recovery factor was improved by 10% OOIP when CTA after water flooding was used in secondary state. The effect of various injection rates and different concentration of chemical solutions on the recovery factor have been checked. Besides, experimental results improved the surfactant behavior of the CTA solution in water. Experiments showed that oil recovery factor increased by 5% OOIP when SDS solution was used in tertiary state. Experiments were performed in laboratory temperature and pressure around 10 bars.