Characterizations of surfactant synthesized from Jatropha oil and its application in enhanced oil recovery

Surfactants are frequently used in chemical enhanced oil recovery (EOR) as it reduces the interfacial tension (IFT) to an ultra‐low value and also alter the wettability of oil‐wet rock, which are important mechanisms for EOR. However, most of the commercial surfactants used in chemical EOR are very expensive. In view of that an attempt has been made to synthesis an anionic surfactant from non‐edible Jatropha oil for its application in EOR. Synthesized surfactant was characterized by FTIR, NMR, dynamic light scattering, thermogravimeter analyser, FESEM, and EDX analysis. Thermal degradability study of the surfactant shows no significant loss till the conventional reservoir temperature. The ability of the surfactant for its use in chemical EOR has been tested by measuring its physicochemical properties, viz., reduction of surface tension, IFT and wettability alteration. The surfactant solution shows a surface tension value of 31.6 mN/m at its critical micelle concentration (CMC). An ultra‐low IFT of 0.0917 mN/m is obtained at CMC of surfactant solution, which is further reduced to 0.00108 mN/m at optimum salinity. The synthesized surfactant alters the oil‐wet quartz surface to water‐wet which favors enhanced recovery of oil. Flooding experiments were conducted with surfactant slugs with different concentrations. Encouraging results with additional recovery more than 25% of original oil in place above the conventional water flooding have been observed. © 2017 American Institute of Chemical Engineers AIChE J, 63: 2731–2741, 2017     

Laboratory Studies to Determine Suitable Chemicals to Improve Oil Recovery from Garzan Oil Field

Garzan oil field is located at the south east of Turkey. It is a mature oil field and the reservoir is fractured carbonate reservoir. After producing about 1% original oil in place (OOIP) reservoir pressure started to decline. Waterflooding was started in order to support reservoir pressure and also to enhance oil production in 1960. Waterflooding improved the oil recovery but after years of flooding water breakthrough at the production wells was observed. This increased the water/oil ratio at the production wells. In order to enhance oil recovery again different techniques were investigated. Chemical enhanced oil recovery (EOR) methods are gaining attention all over the world for oil recovery. Surfactant injection is an effective way for interfacial tension (IFT) reduction and wettability reversal. In this study, 31 different types of chemicals were studied to specify the effects on oil production. This paper presents solubility of surfactants in brine, IFT and contact angle measurements, imbibition tests, and lastly core flooding experiments. Most of the chemicals were incompatible with Garzan formation water, which has high divalent ion concentration. In this case, the usage of 2-propanol as co-surfactant yielded successful results for stability of the selected chemical solutions. The results of the wettability test indicated that both tested cationic and anionic surfactants altered the wettability of the carbonate rock from oil-wet to intermediate-wet. The maximum oil recovery by imbibition test was reached when core was exposed 1-ethly ionic liquid after imbibition in formation water. Also, after core flooding test, it is concluded that considerable amount of oil can be recovered from Garzan reservoir by waterflooding alone if adverse effects of natural fractures could be eliminated.     

微乳液泡沫驱油技术原理、挑战和研究进展

微乳液驱和泡沫驱是强化采油领域中的两个重要技术。前者利用表面活性剂形成油-水微乳液提高增溶能力,降低油水界面张力和毛细管阻力,从而提高驱替效率和微观采收率;后者利用泡沫剂将气体稳定地分散在水相中,在油藏孔隙中形成泡沫,封堵优势通道和已驱替区域,从而扩大波及体积并提高宏观采收率。通过综述两个技术的国内外发展历史和研究进展,阐明了其优势和局限性。近年来提出的微乳液泡沫驱油技术,又称为低张力泡沫驱,其既可以保留两个独立技术的优势,又可以克服他们的缺点,最终同时提高微观和宏观采收率。但是在实际研究中,微乳液泡沫驱技术却面临理论和应用上的双重挑战。通过调查国内外相关研究进展,详细阐述了微乳液泡沫驱技术目前面临的挑战、研发思路和研究建议。     

微乳液泡沫驱油技术原理、挑战和研究进展

微乳液驱和泡沫驱是强化采油领域中的两个重要技术,可以分别提高驱油过程的微观和宏观采收率.通过综述两个技术在国内外的发展历史和研究进展,阐明了其优势和局限性,并引出结合两者优势的新型采油技术:微乳液泡沫驱,又称为低张力泡沫驱.虽然此新型技术可以同时提高微观和宏观采收率,但是在实际应用中,仍然面临理论和应用上的双重挑战,如...     

双重非均质模型凝胶调驱动态特征物理模拟实验研究

针对非均质油藏,制作了带含油饱和度监测能力和测压孔的人造环氧树脂胶结平面、纵向双重非均质模型,并在其上开展了凝胶调驱物理模拟实验。对整个调驱过程中的采收率、含水率、压力、含油饱和度动态变化特征进行了分析,实验结果表明:调驱剂在后续水驱阶段仍然能够增加注入压力、降低含水率;非均质程度较大的油藏,剩余油从纵向上看主要分布在中低渗透层,从平面上看主要分布在远离注入井和主流线的两翼部位,但整个驱替过程之后仍有10%以上的残余油,可以采用提高洗油效率驱油方法继续提高采收率。     

国内轻质油藏注空气、空气泡沫提高采收率效果分析

在重点调研国内油田空气、空气泡沫驱的基础上,论述了注空气、空气泡沫低温氧化技术的原理,对我国油田开展注空气、空气泡沫驱技术的实际效果以及潜力进行了的分析,认为注空气低温氧化工艺技术安全可控,不但可以解决我国储量丰富的低渗透油藏所面临的开发难题,而且可以进一步提高水驱、聚合物驱后油藏的采收率。随着技术进步,注空气低温氧化技术是我国乃至全世界注气提高采收率技术发展的必然趋势。并通过对现场应用情况分析,给出了对轻质油藏注空气、空气泡沫提高采收率的一些建议。     

Synergistic surfactant mixtures containing lignosulphonates

Enhanced oil recovery (EOR) schemes have been gaining importance over the past several years. Of the various methods being tested, surfactant (or micellar) flooding appears to be one of the most promising ones. It involves injecting into the well the solution of a surfactant which reduces the inter-facial tension between the displacing aqueous solution and the oil trapped in the reservoir. Depending on the concentration of the surfactant, oil displacement proceeds either by a miscible process (surfactant concentration > 10%) or by a immiscible process (surfactant concentration = 2–3%). Miscible flooding converts to the immiscible process as the system is diluted by connate (interstitial) water. Under immiscible conditions, the most significant parameter affecting recovery is the interfacial tension^(1,2). Petroleum sulfonates are perhaps the most important group of surfactants capable of producing very low interfacial tensions between crude oil and the water phase. Their relatively high cost, however, renders many potential applications uneconomical.     

瓦窑堡油田羊马河区调剖技术研究

瓦窑堡油田羊马河区位于陕西省子长县境内,构造位置处于鄂尔多斯盆地陕北斜坡的中东部。主力油层为长2层。油层具有储油物性较好,油藏整装连片,油藏丰度大等特点。但油藏同样具有低孔、低渗、低含油饱和度的特点,属于地质构造活动较弱的岩性油藏。经过多年来的注水开发作业,该区已经取得不错的产量,但同时也带来了很多问题,岩石孔隙经过长年的冲刷已经形成大孔道,注入水将沿着大孔道从注水井流入采油井,其余含油孔隙将无法被驱出,使得产油量大幅度直线下降。为此,采用调剖堵水技术,将大孔道封堵,注入水进入含油孔隙,使油井达到高产、稳产的目的,进一步提高采收率。     

Experimental study of secondary and tertiary modes combined low salinity water and polymer flooding in sandstone porous media

Combined low salinity water (LSW) and polymer (LSP) flooding is the most attractive method of enhanced oil recovery (EOR). Considerable research has investigated effective mechanisms of LSP flooding. In this study, 10 laboratory core flood tests were carried out to evaluate the effects of LSW injection into samples without any clay particles, the timing of LSW injection, and the advantages of adding polymer to the injection water for EOR. Secondary and tertiary LSW injections were performed on sandpack samples with different wettability states and water salinity. Tertiary LSW injection after secondary synthetic seawater (SSW) injection in oil-wet samples resulted in 13% more oil recovery, while the water-wet sample showed no effect on the oil recovery. Secondary LSW injection in oil-wet porous media improved oil recovery by 8% of the original oil in place (OOIP) more than secondary SSW injection. Tertiary LSP flooding after secondary SSW injection in the oil-wet sample provided a recovery of 67.3% of OOIP, while secondary LSW injection followed by tertiary LSP flooding yielded the maximum ultimate oil recovery of about 77% of OOIP. The findings showed that the positive EOR effects of LSW and LSP flooding were the results of wettability alteration, pH increase, improved mobility ratio, better sweep efficiency, and oil redistribution. In addition, results showed that wettability alteration is possible without the presence of clay particles. The findings of this study can help for a better understanding of fluid propagation through the porous media and an investigation of delays in reaching ultimate oil recovery.     

S/P二元复合驱相对渗透率曲线研究

模拟油藏实际开发状况,采用非稳态法的物理模拟驱替实验测定了相对渗透率曲线;测定了岩心基本参数,建立二元复合驱和四块表面活性剂驱相对渗透率曲线;通过相对渗透率曲线给出含水饱和度、束缚水饱和度和采收率等其它参数。同时分析油层润湿性、孔隙结构和产油量变化趋势,通过三种不同岩心模拟驱替实验相对渗透率曲线对比,得出二元复合驱适合该油藏的油田开发。     

Formulation for chemical EOR: Development and evaluation of an ASP formulation In customer field conditions

Alkali surfactant polymer (ASP) flooding is an enhanced oil recovery (EOR) technology with an impressive potential for increasing incremental oil production from conventional hydrocarbon bearing reservoirs. A challenge to ASP application is the complexity of determining an effective formulation, typically requiring extensive laboratory screening of nearly countless combinations of surfactants and cosolvents. This paper focuses on demonstrating the utility of the hydrophilic–lipophilic deviation (HLD) concept for EOR application to simplify surfactant formulation workstreams seeking an economically viable ASP formulation for field application. In describing work performed for EOR application of ASP under customer conditions using crude oil, the discussion covers the initial evaluation of the promising surfactant formulation (interfacial tension and solubility), the improvement upon the formulation via HLD principles, and the evaluation of the improved surfactant formulation (coreflood studies). The final ASP formulation identified consisted of a 9 to 1 mixture of alkyl propoxy sulfate sodium salt (APS) to alkyl ethoxy sulfate sodium salt (AES) totaling 2000 ppm active surfactant content, 2.0 wt% Na₂CO₃, and 3000 ppm polyacrylamide polymer (all commercially available products). This formulation had ultra-low interfacial tension and favorable mixing behavior under reservoir conditions. In coreflood studies, the final formulation reproducibly achieved cumulative oil recovery of 96.4%–98.5% of original oil in place with only 0.3 PV of ASP injection with a chase alkali polymer injection.     

考虑非平衡状态的裂缝性油藏周期注水分析

周期注水主要是利用毛管力的自吸作用，使低渗透层的油流入高渗透层，如此反复，低渗透层的油不断被采出，从而提高了油藏的采收率。在常规数值模拟中，相对渗透率是饱和度的函数，与时间无关。然而，实际周期注水的吸入过程是一种典型的非平衡过程，相对渗透率不但是饱和度的函数，还是时间的函数。而常规周期注水工艺和数值模拟研究中，却忽略了这个影响，导致周期注水效果与预期结果不符。基于Barenblatt的非平衡模型，本文研究了非平衡自吸过程对周期注水提高采收率的影响。结果表明考虑非平衡自吸过程后，周期注水提高采收率的程度比常规数值模拟周期注水所预期的要差，特别是在高含水期，非平衡自吸过程的影响会更加突出。这为我们选择和使用周期注水这一工艺提供了一定的指导意义。     

Adaptability of a hydrophobically associating polyacrylamide/mixed‐surfactant combination flooding system to the Shengli Chengdao oilfield

We investigated the performance of a combination flooding system composed of hydrophobically associating polyacrylamide (HAPAM) and a mixed surfactant [fatty acid disulfonate anionic gemini surfactant (DMES) plus the nonionic surfactant Triton X‐100 (TX‐100)] under the reservoir conditions of the Shengli Chengdao oilfield. With 1800 mg/L HAPAM and 300–3000 mg/L mixed surfactant, the surfactant–polymer (SP) flooding system reached an ultralow oil–water interfacial tension, and the viscosity of the system was greater than 40 mPa s. After the solution was aged for 120 days, its viscosity was still more than 40 mPa s; this indicated a good aging stability. The core flooding experiments with different porous media permeabilities showed that the SP flooding system created a higher resistance factor and residual resistance factor. In addition, the indoor flooding experiments indicated that the SP combination flooding system increased the enhanced oil recovery by more than 30% over that of the original oil in place compared with the water flooding system. Therefore, it was feasible to use an SP flooding system in the Chengdao oilfield. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40390.     

Evaluating the performance of designed terpolymers for polymer flooding

In this work, polymeric materials designed for enhanced oil recovery (EOR) were evaluated for their intended application. Properties including viscosity, flow through porous media (resistance factor and residual resistance factor), and heavy oil displacement (incremental oil recovery) were assessed for designed terpolymers of 2-acrylamido-2-methylpropane sulphonic acid (AMPS), acrylamide (AAm), and acrylic acid (AAc). The same properties were evaluated for two commercially available reference materials (e.g., partially hydrolyzed polyacrylamides or HPAM) with similar characteristics, which allowed for direct comparison between the newly designed terpolymers and materials that are currently on the market for the polymer flooding application. The incremental oil recovery directly associated with polymer flooding, which includes both the polymer flooding and post-polymer waterflooding stages (excluding the initial waterflooding injection (or secondary) oil recovery), demonstrates that the designed terpolymers provided a higher incremental recovery (42% and 58%) than the reference materials (33% and 46%). Therefore, the terpolymers provided a higher contribution to incremental (or enhanced) oil recovery than the typical HPAM. Additionally, both designed terpolymers showed better injectivity in unconsolidated porous media and are less likely to cause plugging than the commercially available reference materials. Therefore, using a targeted design approach ultimately led to polymeric materials with excellent performance for EOR polymer flooding applications.     

Surfactant flooding characteristics of dodecyl alkyl sulfate for enhanced oil recovery

Surfactant-enhanced oil recovery is a type of enhanced oil recovery (EOR), a method to produce residual oil by injecting surfactant solution into the reservoir. The application of surfactant EOR requires knowledge of the phase behavior for more efficient production of residual oil.In this study, the relationship between dodecyl alkyl sulfate and some specific crude oils was examined through phase behavior test. It was found that the branched surfactant was more effective than the linear surfactant. The system was stable at salinities <3 wt%. On adding a small amount of co-surfactant, the emulsion activity was increased.The gravity drainage flooding test (GDFT) was performed to determine the potential of dodecyl alkyl sulfate to produce residual oil in porous media. It was found that the solution could be flooded at temperatures of 60 °C or higher. In the core flooding test, injecting one pore volume of 2 wt% surfactant solution with 3 wt% salinity produced 26.6% more oil after water flood. With the addition of only 0.01 wt% co-surfactant, oil production increased by 1.6%. Contrary to the phase behavior test, the linear surfactant produced 1.3% more oil than the branched surfactant in the core flooding test.     

Experimental Study of In-Situ CO<Subscript>2</Subscript> Foam Technique and Application in Yangsanmu Oilfield

The Yangsanmu oilfield of Dagang is a typical heavy oil reservoir. After the maximum primary production (waterflooding), more than half of the original oil is still retained in the formation. Therefore, the implementation of an enhanced oil recovery (EOR) process to further raise the production scheme is inevitable. In this work, a novel in-situ CO₂ foam technique which can be used as a potential EOR technique in this oilfield was studied. A screening of gas producers, foam stabilizers and foaming agents was followed by the study of the properties of the in-situ CO₂ foam systems through static experiments. Core-flooding experiments and field application were also conducted to evaluate the feasibility of this technique. The results indicated that the in-situ CO₂ foam system can improve both the sweep and displacement efficiencies, due to the capacity of this system in reducing oil viscosity and interfacial tension, respectively. The EOR performance of the in-situ CO₂ foam system is better than the single-agent and even binary system (surfactant-polymer) flooding. The filed data demonstrated that the in-situ CO₂ technique can significantly promote oil production and control water cuts. These results are believed to be beneficial in making EOR strategies for similar reservoirs.     

The impact of connate water saturation and salinity on oil recovery and CO2 storage capacity during carbonated water injection in carbonate rock

Carbonated water injection (CWI) is known as an efficient technique for both CO₂ storage and enhanced oil recovery (EOR). During CWI process, CO₂ moves from the water phase into the oil phase and results in oil swelling. This mechanism is considered as a reason for EOR. Viscous fingering leading to early breakthrough and leaving a large proportion of reservoir un-swept is known as an unfavorable phenomenon during flooding trials. Generally, instability at the interface due to disturbances in porous medium promotes viscous fingering phenomenon. Connate water makes viscous fingers longer and more irregular consisting of large number of tributaries leading to the ultimate oil recovery reduction. Therefore, higher in-situ water content can worsen this condition. Besides, this water can play as a barrier between oil and gas phases and adversely affect the gas diffusion, which results in EOR reduction. On the other hand, from gas storage point of view, it should be noted that CO₂ solubility is not the same in the water and oil phases. In this study for a specified water salinity, the effects of different connate water saturations (S_wc) on the ultimate oil recovery and CO₂ storage capacity during secondary CWI are being presented using carbonate rock samples from one of Iranian carbonate oil reservoir. The results showed higher oil recovery and CO₂ storage in the case of lower connate water saturation, as 14% reduction of S_wc resulted in 20% and 16% higher oil recovery and CO₂ storage capacity, respectively.     

复杂断块聚驱后注聚/表二元复合驱可行性研究

港西油田总体处于高含水高采出程度的开发阶段,聚合物驱油技术在港西油田推广应用已24年,聚合物驱控制地质储量占油田总储量的21.9%,聚合物驱后如何进一步提高采收率是港西油田面临的重要技术难题。经证实聚驱后二元复合驱技术可以进一步提高采收率,本文重点介绍港西三区聚驱后注聚/表二元复合驱技术提高采收率的室内研究、实施方案优化和现场应用效果分析,从而验证了聚驱后注聚/表二元驱提高采收率技术在港西油田复杂断块"双高"油藏条件下的可行性。     

二类油层精细地质解剖与综合挖潜技术方法

"十一五"以来,二类油层聚合物驱实现了由工业性试验向工业化推广应用的转变,但在工业化推广过程中,对二类油层精细地质认识不够清楚,缺乏分阶段跟踪调整方法,区块及井点间受效不均衡、层内及层间动用状况差异明显的矛盾仍然较为突出。利用精细地质研究成果,深入认识了北一二排二类油层的地质特点,通过数值模拟技术,明确了二类油层聚合物驱调整技术及措施优化设计方法,采用分注及油水井措施改造的方法减小平面、层间、井间差异。分注后油层动用状况提高6.2个百分点,油水井措施改造后,注入井平均日增注19m3,采出井平均日增油9t。二类油层平面纵向非均质性严重,在注聚不同阶段需要加大改造力度,分层注聚和调剖提高了油层的动用程度,扩大了波及体积,对改善二类油层聚驱开发效果有重要的指导意义。     

Heavy oil recovery efficiency using SAGD,SAGD with propane co-injection and STRIP-SAGD

Primary oil recovery methods in heavy oil basins generally extract 5–10% of the available resource, with the vast majority left in the ground and recoverable only through Enhanced Oil Recovery (EOR) methods. Traditional EOR methods, such as SAGD and solvent-assisted SAGD, generate steam in surface facilities and inject it underground to mobilize the oil for production. However, these methods can have considerable energy losses that significantly impact process performance. In contrast, the Solvent Thermal Resource Innovation Process (STRIP) technology, which uses down hole combustion of methane to produce CO₂ and steam, reduces the operating and capital costs of surface facilities, saving more than 50% of the energy typically required for thermal production. In this work, simulations of conventional SAGD, SAGD with a non-condensing solvent (propane), and STRIP-SAGD for a typical bitumen reservoir in the Fort McMurray region in Alberta, Canada were performed using the combined software system ADGPRS/GFLASH. SAGD simulations used steam injection with a quality of 0.8 while STRIP simulations injected a vapor–liquid mixture with a quality of 0.8. Furthermore, both solvent-based EOR methods required longer operation periods than conventional SAGD to recover a similar amount of oil. However, when compared on the basis of cumulative oil produced for the same overall energy input, it is shown that STRIP-SAGD recovered more oil per kJ of energy input to the reservoir than either SAGD or SAGD with propane co-injection.