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。     

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。     

黏土矿物对化学驱提高采收率的影响

以当前各大油田储层矿物组成情况为基础,研究了油田常见4种黏土矿物(高岭石、蒙脱石、绿泥石、伊利石)对化学驱提高采收率的影响。通过在石英砂中添加相同含量的不同黏土,进行了室内填砂管模拟实验研究。结果表明,黏土矿物的存在对化学驱提高采收率有很大的影响,含有黏土矿物的模型化学驱提高采收率明显要低于纯石英砂模型;在相同含量的黏土中,蒙脱石矿物对化学驱提高采收率影响最大;绿泥石的存在对聚合物注入压力有很大影响。     

Effect of foam density,oil viscosity,and temperature on oil sorption behavior of polyurethane

This paper examines the effect of foam density, oil viscosity, and temperature on the oil sorption behavior of polyurethane foams. Four polyurethane foams with different densities and two oil types with different viscosities were investigated. The amount of oil uptake was measured gravimetrically. Oil transport through the foams was analyzed by nondestructive X‐ray microtomography. Oil sorption capacity increased significantly with the decrease in foam density, due to the increase in the number of open cells. The oil sorption capacity depended only slightly on sorption temperature and oil viscosity. X‐ray visualization allowed pore filling behavior to be observed directly, and further scope to extend the technique is revealed. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 360–367, 2006     

岩石表面可润湿性反转对二元复合驱提高采收率的影响

考察了克拉玛依石油磺酸盐(KPS)、磺基甜菜碱(BS)、脂肪胺聚氧乙烯醚(FAPE)和十二烷基二甲基苄基氯化铵(1227)等4种表面活性剂的溶液改变含油天然岩芯砂模型表面可润湿性的能力和对新疆油田七东1区原油的静态洗油效率。分别将KPS,BS和FAPE与聚丙烯酰胺(KYPAM-2)组成二元复合体系,测试了KPS/KYPAM-2,BS/KYPAM-2和FAPE/KYPAM-2二元体系与1227溶液对原油的界面张力,并计算了它们剥离岩石表面油滴所需克服的粘附功,最后利用上述二元体系与1227溶液进行了驱油效率的考察。结果表明:4种表面活性剂溶液均能使岩石表面的可润湿性由油性润湿向中性或水性润湿反转;其中BS的粘附功为0.018 J,静态洗油效率为85.7%,BS/KYPAM-2二元体系水驱后提高采收率12.7%,在4种表面活性剂里性能最好。     

化学驱提高辽河油田原油采收率研究

针对辽河油田区块的油藏条件,在室内进行了无碱二元驱和弱碱三元驱提高原油采收率的研究。对3种表面活性剂SL-YD、HL-1、BH进行了筛选,优选出了对该地层原油具有最佳降低界面张力效果的表面活性剂SLYD和HL-1;然后与聚合物PAM复配,组成二元体系,最佳配方为0.16%PAM+0.20%SL-YD;最后筛选得出了弱碱三元体系0.16%PAM+0.15%SL-YD+0.30%Na2CO3。室内实验表明,无碱二元体系和弱碱三元体系可以使油水界面张力降到10-3mN/m以下,可以大幅度提高原油的采收率,增幅超过10%。     

鲁克沁超深层特稠油空气泡沫驱起泡体系实验研究

针对鲁克沁稠油油藏埋藏深度大、油层温度及原油粘度高、非均质性严重等特征,筛选出了适合于鲁克沁稠油空气泡沫驱的起泡剂体系。通过配伍性和气泡体系评选实验,确定了最佳起泡体系为0.6%质量分数的起泡剂ZFC+1 500 mg/L的稳泡剂ZSX。泡沫稳定性实验结果表明,该起泡体系具有较好的抗温、耐盐、抗油及抗老化性能;泡沫体系动态封堵实验表明,气液比为1∶1时,该起泡体系泡沫的阻力因子达108.4,随渗透率的增大,泡沫阻力因子增加;泡沫驱油试验表明,该泡沫体系可以显著提高低渗层动用程度,低渗管采出程度增加了16.37%。     

砾岩油藏聚驱后提高采收率技术研究

在分析聚驱后剩余油的分布特点的基础上,从室内研究和现场应用等方面评价了聚合物驱后进一步提高油田采收率技术———聚合物驱后残留聚合物再利用技术、聚合物驱后深部调剖技术、聚合物驱后高效洗油技术,并结合砾岩油藏的储层物性和已有的砾岩油藏二次开发经验,提出了适合砾岩油藏聚驱后进一步提高采收率技术的方案。     

硅油粘度对ABS／硅油混合物性能的影响

通过硅油粘度对ABS／硅油混合物性能的影响进行比较深入的研究,从而最终确定了制作门内基板、门立柱等轿车内装件用ABS／硅油混合物专用料所使用的硅油粘度范围。     

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.     

Investigating the effect of nano-silica on efficiency of the foam in enhanced oil recovery

Due to the vast production of crude oil and consequent pressure drops through the reservoirs, secondary and tertiary oil recovery processes are highly necessary to recover the trapped oil. Among the different tertiary oil recovery processes, foam injection is one of the most newly proposed methods. In this regard, in the current investigation, foam solution is prepared using formation brine, C₁₉TAB surfactant and air concomitant with nano-silica (SiO₂) as foam stabilizer and mobility controller. The measurements revealed that using the surfactant-nano SiO₂ foam solution not only leads to formation of stable foam, but also can reduce the interfacial tension mostly considered as an effective parameter for higher oil recovery. Finally, the results demonstrate that there is a good chance of reducing the mobility ratio from 1.12 for formation brine and reservoir oil to 0.845 for foam solution prepared by nanoparticles.     

Carbon dioxide flooding for enhanced oil recovery: Promise and problems

Of the enhanced oil recovery methods currently being considered for application to many of the nation’s older oil fields, carbon dioxide flooding may offer the largest potential for additional oil recovery. The physical mechanisms by which CO₂ contacts and mobilizes crude oil are reviewed. Influence on the displacement process of factors such as the phase behavior of CO₂-crude oil mixtures, swelling of oil by dissolved CO₂, and reduction of oil viscosity are considered. Adverse effects of the viscous instability which occurs when very low viscosity CO₂ displaces the more viscous oil and water are dicussed. Advantages and disadvantages of three potential methods for controlling the mobility of CO₂ are reviewed: thickening CO₂ with polymeric additives, reduction of CO₂ mobility by high water saturations, and use of surfactants to generate foam-like emulsions of water and CO₂. Field experience to date and the recent surge in field activity are discussed. Finally, a brief assessment of the future of CO₂ flooding research and practice is offered.     

Effect of hydrogenation on density and viscosity of sunflowerseed oil

The densities and viscosities of unhydrogenated and hydrogenated sunflowerseed oils have been determined at temperatures ranging from 25 to 50°C at 5°C intervals. The densities of these oils vary linearly with temperature. The values of the parameters for the density equation have been calculated. Smooth curves were obtained when the changes in viscosity with temperature were plotted in the form of ln η vs. 1/T. The energy of activation, the free energy of activation, and the entropy of activation have been calculated at 25°C, and they decreased with the degree of unsaturation in the fatty acid chains of the sunflowerseed oil.     

注CO2气驱提高采收率效果影Ⅱ向因素分析

目前油田常规注水开发难度不断增加,应用注CO2气驱技术能够有效解决注水困难等问题,提高了原油采收率。在室内实验研究的基础上,应用数值模拟技术优化了注气方式及注气时机;分析了油藏地质参数对注CO2气驱提高采收率的影响。研究表明：水气交替注入方式更优;非均质性越强,开发效果越差;油藏渗透率越大、含油饱和度越高、原油粘度越低,注CO2驱油效果越好。     

中高含水油藏聚驱后进一步提高采收率技术研究

针对冀东油田南堡断块油藏聚驱后大孔道发育、前期常规调剖措施效果差等问题,研究一种利用残留聚合物的絮凝剂和冻胶复合体系新技术,其中絮凝体系配方:4%潍坊改性钠土(CX-1)+0.06%稳定剂Na_2CO_3;冻胶体系配方为:0.5%~0.6%聚合物YG100+0.6%~0.7%交联剂YJ-1+0.016%~0.017%交联剂TJ-1。长岩心驱替实验表明,注入复合体系后,高渗通道的渗透率降低93%,是因为复合体系中CX-1与岩心残留聚合物发生絮凝作用,形成粒径较大的絮凝体,封堵高渗通道,冻胶成冻后通过吸附和滞留方式封堵渗透层。纵向三层非均质岩心驱油实验表明,在不同高含水时期,均能大幅度提高原油采收率12.5%以上。     

空气泡沫驱氧化机理实验研究

空气泡沫驱是一种特别适合低渗透油藏提高原油采收率的技术,它不仅具有一般注气的作用,而且还具有氧化反应产生的其它效果。但是如果注入空气中的氧与原油反应不充分,在原油中O2与甲烷气体的含量达到爆炸所需的有效浓度时,就有可能发生爆炸现象。因此,O2的含量是决定注空气泡沫工艺成败的关键因素。本文通过空气氧化静态实验,模拟原油在不同温度下的低温氧化过程,研究原油与空气接触后的氧化速率、含氧量及原油组分的变化,并分析了影响原油低温氧化反应的因素,为现场注气安全性的分析提供了理论基础。     

Correlations between interfacial tension and cumulative tertiary oil recovery in a triglyceride microemulsion flooding

This paper presents measurements of interfacial tension (IFT) and tertiary oil recovery (TOR) of triglyceride microemulsion flooding over a wide range of aqueous phase compositions. Based on 160 experimental data sets, two empirical correlations were established. Both the power-law and logarithmic models were validated statistically. Power-law and logarithmic models are predicted to perform best at ultralow IFT range (<0.001 mN/m) and high IFT range (>2 mN/m), respectively. The valid models indicate that IFT is the sole parameter affecting the cumulative TOR in a triglyceride microemulsion flooding. This phenomenon, however, does not apply in hydrocarbon-based microemulsions.     

Enhanced heavy oil recovery through interfacial instability: A study of chemical flooding for Brintnell heavy oil

This study is aimed at developing an alkaline/surfactant-enhanced oil recovery process for heavy oil reservoirs with oil viscosities ranging from 1000 to 10,000 mPa s, through the mechanism of interfacial instability. Instead of the oil viscosity being reduced, as in thermal and solvent/gas injection processes, oil is dispersed into and transported through the water phase to production wells.Extensive emulsification tests and oil/water interfacial tension measurements were conducted to screen alkali and surfactant for the oil and the brine samples collected from Brintnell reservoir. The heavy oil/water interfacial tension could be reduced to about 7 × 10⁻² dyn/cm with the addition of a mixture of Na₂CO₃ and NaOH in the formation brine without evident dynamic effect. The oil/water interfacial tension could be further reduced to 1 × 10⁻² dyn/cm when a very low surfactant concentration (0.005-0.03 wt%) was applied to the above alkaline solution. Emulsification tests showed that in situ self-dispersion of the heavy oil into the water phase occurred when a carefully designed chemical solution was applied.A series of 21 flood tests were conducted in sandpacks to evaluate the chemical formulas obtained from screening tests for the oil. Tertiary oil recoveries of about 22-23% IOIP (32-35% ROIP) were obtained for the tests using 0.6 wt% alkaline (weight ratio of Na₂CO₃ to NaOH = 2:1) and 0.045 wt% surfactant solution in the formation brine. The sandpack flood results obtained in this project showed that a synergistic enhancement among the chemicals did occur in the tertiary recovery process through the interfacial instability mechanism.     

Improving oil recovery in the CO2 flooding process by utilizing nonpolar chemical modifiers☆

By means of experiments of CO2 miscibility with crude oil, four nonpolar chemicals were evaluated in order to enhance the miscibility of CO2 with crude oil. Through pre-slug injection and joint injection of toluene in CO2, crude oil displacement experiments in the slim-tube were conducted to investigate effects of the toluene-enhanced CO2 flooding under simulated subterranean reservoir conditions. Experimental results showed that toluene can enhance extraction of oil into CO2 and dissolution of CO2 into oil with the increment of 251%and 64%respectively. Addition of toluene can obviously improve the oil recovery in either pre-slug injection or joint injection, and the crude oil recovery increased with the increase of the toluene concentration. The oil recov-ery can increase by 22.5%in pre-slug injection with the high toluene concentration. Pre-slug injection was recom-mended because it can consume less toluene than joint injection. This work could be useful to development and application of the CO2 flooding in the oil recovery as wel as CO2 emission reduction.     

Evaluation of aqueous chemical systems for heavy oil recovery processes

The effects of temperature and certain chemical additives on the interfacial tension behaviour of a heavy oil (from Lloydminster, Alberta) with petroleum sulphonate surfactant solutions and alkaline solutions are investigated experimentally. Corresponding data for a light Canadian oil are included for comparison purposes. It is concluded that alkaline solutions are effective only in the recovery of heavy oils, while petroleum sulphonate surfactants are effective only for light oils. The effect of temperature on the minimum attainable interfacial tension is marginal in all cases. However, for alkaline solutions, temperature has a significant effect on the rate of rise of interfacial tension with time after attainment of the minimum value.