泡沫驱提高采收率技术研究新进展

泡沫驱提高采收率技术研究新进展主要集中在:①气-液-固三相泡沫驱,包括纳米颗粒泡沫、膨润土泡沫和粉煤灰泡沫;②微泡沫驱;③自生气泡沫驱,包括自生CO_2泡沫和自生N_2泡沫;④泡沫复合驱,包括泡沫-凝胶深部调驱、冻胶泡沫强化封堵;⑤泡沫-物理法复合技术提高采收率,包括泡沫-振动波综合调驱、泡沫-热力采油。就以上技术展开综述,介绍了研究进展、作用机制和存在问题,并对下一步研究进行了展望。     

Pelargonic acid in enhanced oil recovery

Oxidation of monounsaturated fatty acids, such as erucic and oleic acids, results in the formation of dibasic fatty acids, such as brassylic and azelaic acids. Dibasic acids find many industrial applications. Pelargonic acid is the co-product of the process. Expanded use of dibasic acids would require an expansion in the existing and possibly new uses for pelargonic acid and its derivatives. In this study, the potential for using pelargonic acid in enhanced oil recovery is investigated. Experimental results are presented for the enhanced oil recovery by waterflooding with the aid of a surfactant.In situ formation of surfactant at the oil-water interface vs. the formation of surfactant in the floodwater prior to injection is examined.     

化学驱油进展

目前,全球石油产量约8 500万桶/天,即超过300亿桶/年。OPEC（石油输出国组织）估计,到2030年,发展中国家的需求将使全球产量提高到1.07亿桶/天。 从给出的一些统计值表明,表面活性剂研究者和生产商有千载难逢的好机会：多数现有的油井只能采出30%的油气,化学驱是可用的、为数不多的二次和三次开采增加石油产量的方法。     

泡沫驱提高油田采收率的研究进展

随着我国各大油田陆续进入开发后期,可供开采的常规油气藏资源越来越少,提高采收率的研究越来越受到重视。气体泡沫驱作为一种有效提高采收率的方式,广泛应用于我国各大油田,在现场应用中发挥了堵塞缝隙、降低出水率、提高采收率的作用。介绍了氮气泡沫驱、二氧化碳泡沫驱、空气泡沫驱在国内外的最新研究进展和现场应用情况,对3种泡沫驱进行了比较;讨论了表面活性剂作为发泡剂对提高油藏采收率的作用和影响。分析了3种泡沫驱油方式的优缺点和适应性,并对未来发展提出建议,认为我国的泡沫驱油技术还未成熟,要针对气体-泡沫注入方式以及注入时机等进行更深层次的研究,同时还要研发发泡剂和稳泡剂的配方,降低成本。     

驱油用烷基苯工业化生产研究

通过进行小批量的驱油用烷基苯生产试验,制定出了切实可行的生产方案,并顺利完成工业化试验和增产试验,驱油用烷基苯产量达到1.6万t/a,试验产品经测试在大庆三厂油水条件下能够达到10-3mN/m的超低界面张力,能够满足大庆三元复合驱强碱体系矿场试验的需求.     

A review on the application of nanofluids in enhanced oil recovery

Enhanced oil recovery (EOR) has been widely used to recover residual oil after the primary or secondary oil recovery processes. Compared to conventional methods, chemical EOR has demonstrated high oil recovery and low operational costs. Nanofluids have received extensive attention owing to their advantages of low cost, high oil recovery, and wide applicability. In recent years, nanofluids have been widely used in EOR processes. Moreover, several studies have focused on the role of nanofluids in the nanofluid EOR (N-EOR) process. However, the mechanisms related to N-EOR are unclear, and several of the mechanisms established are chaotic and contradictory. This review was conducted by considering heavy oil molecules/particle/surface micromechanics; nanofluid-assisted EOR methods; multiscale, multiphase pore/core displacement experiments; and multiphase flow fluid-solid coupling simulations. Nanofluids can alter the wettability of minerals (particle/surface micromechanics), oil/water interfacial tension (heavy oil molecules/water micromechanics), and structural disjoining pressure (heavy oil molecules/particle/surface micromechanics). They can also cause viscosity reduction (micromechanics of heavy oil molecules). Nanofoam technology, nanoemulsion technology, and injected fluids were used during the EOR process. The mechanism of N-EOR is based on the nanoparticle adsorption effect. Nanoparticles can be adsorbed on mineral surfaces and alter the wettability of minerals from oil-wet to water-wet conditions. Nanoparticles can also be adsorbed on the oil/water surface, which alters the oil/water interfacial tension, resulting in the formation of emulsions. Asphaltenes are also adsorbed on the surface of nanoparticles, which reduces the asphaltene content in heavy oil, resulting in a decrease in the viscosity of oil, which helps in oil recovery. In previous studies, most researchers only focused on the results, and the nanoparticle adsorption properties have been ignored. This review presents the relationship between the adsorption properties of nanoparticles and the N-EOR mechanisms. The nanofluid behaviour during a multiphase core displacement process is also discussed, and the corresponding simulation is analysed. Finally, potential mechanisms and future directions of N-EOR are proposed. The findings of this study can further the understanding of N-EOR mechanisms from the perspective of heavy oil molecules/particle/surface micromechanics, as well as clarify the role of nanofluids in multiphase core displacement experiments and simulations. This review also presents limitations and bottlenecks, guiding researchers to develop methods to synthesise novel nanoparticles and conduct further research.     

Characterization of polyacrylamides used in enhanced oil recovery

Polyacrylamides can be readily characterized using techniques such as IR spectroscopy, ¹³C-NMR, elementary analysis, TGA, and x-ray diffraction. The first three techniques can also be used quantitatively to measure the degree of hydrolysis of the polymers, without the need to know accurately the weight of the sample. The presence of inorganic salts, such as Na₂SO₄, Na₄(CO₃)SO₄, and Na₂CO₃, is readily detected via IR or wide-angle x-ray diffraction. No evidence of crystallinity is found in the samples studied.     

The influence of nano-silica on the thermal conductivity of polyurethane foam

This study reports the influence of nano-silica particles (0.0–0.45 %wt) on properties of polyurethane foams (PUF) using monoglycerides, sorbitol, and glycerol as components of polyol. The morphology, density, mechanical, thermal stability, and thermal conductivity properties of samples were investigated in this study. When 0.35 %Wt of nano-silica was used to reinforce PUF, the compression strength of PUF achieved the highest value (82.49 kPa). The thermal gravimetric analysis showed that the presence of nano-silica can improve the thermal stability of PUF samples. Scanning electron microscopy studies indicated that PUF samples containing 0.3, 0.35, and 0.45 %Wt of nano-silica had more uniform cell structures than pure PUF sample. Finally, the thermal conductivity of pure PUF and PUF/nano-silica were measured at three different levels of humidity (33% RH, 57% RH and 75% RH) at 25°C. The lowest thermal conductivity value achieved was 0.034 W/mK.     

Effect of oil viscosity on recovery processes in relation to foam flooding

Laboratory experiments were conducted to determine the effect of oil viscosity on the oil-recovery efficiency in porous media. The pure surfactants (i.e., sodium dodecyl sulfate and various alkyl alcohols) were selected to correlate the molecular and surface properties of foaming solutions with viscosity, and the recovery of oil. Oil-displacement efficiency was measured by water, surfactant-solution and foam-flooding processes, which included 2 types of foams (i.e., air foam and steam foam). A significant increase in heavy-oil recovery was observed by steam foam flooding compared with that by air foam flooding, whereas for light oils, the steam foam and air foam produced about the same oil recovery. An attempt was made to correlate the chain-length compatibility with the surface properties of the foaming agents and oil-recovery efficiency in porous media. For mixed foaming systems (C₁₂ SO₄ Na + C_n H_2n+1 OH), a minimum in surface tension, a maximum in surface viscosity, a minimum in bubble size and a maximum in oil recovery were observed when both components of the foaming system had the same chain length. These results were explained on the basis of thermal motions (i.e., vibrational, rotational and oscillational) and the molecular packing of surfactants at the gas-liquid interface. The effects of chain-length compatibility and the surface properties of mixed surfactants are relevant to the design of surfactant formulations for oil recovery under given reservoir conditions.     

Spontaneous emulsification aspect of enhanced oil recovery

Recent studies have suggested the possibility of spontaneous emulsification as a mechanism for enhanced oil recovery (EOR). The discussions have, however, remained essentially qualitative. A study was therefore undertaken to estimate quantitatively the contribution of spontaneous emulsification as an EOR mechanism. The tests were conducted on several bulk liquid/liquid systems as well as by displacement experiments in unconsolidated synthetic sand packs. Spontaneous emulsification was found to be a mechanism for EOR: the estimated extra contribution to EOR due to this mechanism was found to be significant in laboratory scale displacement experiments. Tertiary recovery was always greater when spontaneous emulsification was evident than otherwise. Results of tests on bulk liquid/liquid systems indicate that the occurrence or absence of spontaneous emulsification can be correlated with the values of ‘partition parameter’. It may be concluded that higher oil recoveries may be achieved in chemical EOR processes where interface mass transfer (and the accompanying spontaneous emulsification) occurs. The evaluation of efficiency of residual oil mobilisation through the capillary number theory (with and without spontaneous emulsification) is also discussed. Displacement tests with spontaneously emulsifying systems showed that residual oil left behind a conventional waterflood was mobilised in a range of capillary numbers much less than that which applies to low-tension waterfloods.     

Modified acrylamide polymers for enhanced oil recovery

Copolymers of sodium acrylate and N-methyl-, N-isopropyl-, N-n-butyl-, and N-t-butylacrylamide were prepared. The viscosities of these copolymers in 0.01% and 2.00% NaCl and their resistances to shear were compared with those of several partially hydrolyzed polyacrylamides. The poly(N-alkylacrylamide-co-sodium acrylate demonstrated somewhat better retention of viscosity in brine than did analagous partially hydrolyzed polyacrylamides. N-alkyl substitution increased sensitivity to shear in low salt solutions.     

重烷基苯磺酸盐在油田三次采油中的应用

简要介绍了油田三次采油的相关情况,系统介绍了重烷基苯磺酸盐在油田三元复合驱的应用及工业化生产过程,分析与探讨了重烷基苯磺酸盐工业化生产中的难点及在大庆油田的应用前景.     

三次采油注聚物静态混合器研究进展

简述了油田三次采油过程中注聚合物的背景,总结了静态混合器的混合机理以及三次采油注聚合物静态混合器的研究现状,并对三次采油注聚物静态混合器的发展进行了展望。     

分光光度法测定三次采油中常用阴离子表面活性剂

确定了一种测定阴离子表面活性剂的方法——分光光度法。通过实验确定了此方法的最佳条件,最大吸收波长为630 nm,阳离子标准溶液（1.0×10-4 mol/L）加量为20 mL,缓冲指示剂的用量为10 mL,静置2 h,温度恒温控制在25℃。同时确定了阴离子表面活性剂的测量范围,应当控制其加量在阳离子表面活性剂加量的一半,工作曲线线性相关系数为0.999 72。并测定了其他常用阴离子表面活性剂的工作曲线,线性相关系数均超过了0.990 00,证明了这种方法应用的普遍性。     

The marangoni effect and enhanced oil recovery Part 1. Porous media studies

The use of partitionable solutes, e.g., aliphatic alcohols, to enhance the recovery of trapped oil in reservoir rock, has been simulated using a ballotini-packed column initially flooded with kerosene, and subsequently lowered to an irreducible value by a water drive. Introduction of a “slug” of an alcohol effected an increased recovery, with n-propanol and sec-butanol giving the highest yields. Previous workers attributed such increased recovery to the formation of a “soluble front”, in which both oil and connate water are completely dissolved. However, we obtained similar recoveries using slugs with initial compositions lying on the miscibility boundary, which could not form soluble fronts. It was therefore concluded that Marangoni-induced oscillation of the trapped drops is the more likely explanation of the enhanced recovery.     

应用石油磺酸盐提高原油采收率的研究进展

综述了国内外应用石油磺酸盐进行三次采油矿场试验的研究现状.介绍了合成石油磺酸盐的原料和工艺以及石油磺酸盐的精细结构.讨论了石油磺酸盐与其他表面活性剂复配体系的低表面张力特性以及在驱油过程中的沉积损耗和在油砂表面上的吸附损耗.指出改性石油磺酸盐和结构性能关系清晰的合成石油磺酸盐是今后的发展趋势.     

Characterization of acrylamide polymers for enhanced oil recovery

Four different copolymers, of acrylamide and acrylic acid, acrylamide and 2‐acrylamido‐2‐methyl propane sulfonic acid, N,N‐dimethylacrylamide and acrylic acid, and N,N‐dimethylacrylamide and 2‐acrylamido‐2‐methyl propane sulfonic acid (sodium salts), were prepared. The copolymers were characterized by their intrinsic viscosities and monomer ratios and with IR, ¹H‐NMR, and X‐ray diffraction (XRD) spectroscopy. No crystallinity was observed by differential thermal analysis, and this was well supported by XRD. All the polymers showed low decomposition temperatures. A number of decomposition temperatures were observed in differential thermogravimetry thermograms because of the elimination of gases such as CO₂, SO₂, CO, and NH₃. The replacement of the acrylate group with a sulfonate group produced polymers that were more compatible with brine, whereas the replacement of acrylamide with a more hydrophobic group such as N,N‐dimethylacrylamide produced a more shear‐resistant polymer. A N,N‐dimethylacrylamide‐co‐sodium‐2‐acrylamido‐2‐methyl propane sulfonate copolymer was better with respect to thermal stability when the polymer solution was aged at 120°C for a period of 1 month. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1869–1878, 2003     

Flow behavior of enhanced oil recovery Alcoflood polymers

Flow behavior in terms of shear stress and viscosity versus shear rate is investigated for aqueous solutions of Alcoflood polymer materials. Rheostress RS100 is employed for operating, measuring, and analyzing this experimental investigation. Polymer concentration in the range of 100–10,000 ppm was covered. Fitting analysis is carried out for all the examined polymer solutions. Casson and Ostwald‐de‐Waele correlations can be employed for predicting flow behavior, depending upon polymer type. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2896–2904, 2002     

Adsorption of surfactant during chemical enhanced oil recovery

Surfactant is extensively used as chemicals during chemical enhanced oil recovery (CEOR) process. Effectiveness of surfactant CEOR process depends on several parameters like formation of micro emulsion, ultra-low interfacial tension (IFT) and adsorption of surfactant. First two parameters enhance the effectiveness while the last parameter reduces the effectiveness. Micro emulsions are highly desirable for CEOR due to its low interfacial tension (IFT) value and higher viscosity. In this research the size of the emulsions were studied with particle size analyzer to study the liquid–liquid absorption process and the entrapment of oil drops inside surfactant drop. Initially, the average surfactant drop size was found to be 100 nm, after mixing the surfactant slug with reservoir crude, the size was increase up to 10 times. It signifies the formation of micro emulsion between surfactant and oil. Another attempt was done in this research to study the adsorption mechanism of surfactant on reservoir rock. The process of adsorption was studied by Langmuir and Freundlich isotherm to understand the adsorption phenomena. In this study, it was found that the adsorption follows Freundlich isotherm and the adsorption phenomena was chemical for surfactant flooding process. In chemical adsorption phenomena, the rate of adsorption is high because, surfactant molecules are adsorbed layer after layer by the rock surface. Use of alkali along with surfactant reduces adsorption of surfactant since, alkali blocked the active clay sites before interacting with surfactant and hence the adsorption isotherm was found to be Langmuir and phenomena was physical adsorption.     

利用采油速度确定油藏采收率

水驱油藏进入高含水开发期以后,常规的水驱曲线对采收率的标定会出现很多问题。本文从渗流力学和物质平衡原理角度出发,推导出处于产量递减期间的油藏采油速度与采出程度之间的关系,发现存在线性特征。利用该关系可以对油藏动态和经济采收率进行标定,并给出了其适用条件。在此基础上利用孤东七区西Ng63 4的生产数据进行了实例验证。