陕北低渗透储层表面活性剂驱油体系研究

针对陕北延长油田的储层情况,研制出一种以甜菜碱为主的复配驱油体系EPS,该体系配方为:甜菜碱:OP-10:异丙醇=7∶2∶1,使用浓度为0.1%。对该体系的配伍性、乳化性、抗盐性、cmc值、吸附值及采收率进行测定。结果表明,该驱油体系与陕北延长油田大部分高矿化度的地层水都有良好的配伍性和乳化性;cmc值较低(450 mg/L);岩心吸附值小(0.910 mg/g);耐盐性能好,当Ca2+浓度高达12 000 mg/L时,该体系与原油仍可达到超低界面张力(约10-3mN/m);在不同低渗透油层的驱替实验中,驱油效率提高6.7%～17.9%。     

矿化度对三元复合体系瞬时界面张力的影响

三元复合驱是一项能大幅度提高原油采收率的三次采油技术,大庆油田以往开展的先导性矿场试验,都取得了较好的效果,比水驱的采收率提高20％以上。在对三元复合驱油体系的评价中,配制用水的矿化度对瞬时界面张力的影响很大。本文针对矿化度对瞬时界面张力的影响,考察了清水配制的2种三元复合体系ω（S）为0．3％＋ρ（P）为1200mg／L＋ω（A）为0．2％（S：表面活性剂,P：聚合物,A：碱）和ω（S）为0．3％＋ρ（P）为1200mg／L＋ω（A）为0．6％的混合液在不同矿化度下与原油之间的瞬时界面张力变化曲线,污水配制的3种配方ω（S）为0．05％＋ρ（P）为1000mg／L＋ω（A）为0．6％、ω（S）为0．2％＋ρ（P）为1000mg／L＋ω（A）为0．8％和ω（S）为0．3％＋ρ（P）为1650mg／L＋ω（A）为1．2％在不同矿化度下的瞬时界面张力变化曲线,得出不同水质矿化度下油水瞬时界面张力出现的变化规律基本相同。     

生物表面活性剂复合体系在强化采油中的应用研究

针对大庆油田小井距生物表面活性剂复合体系先导性矿场试验 ,利用自行研制并生产的6 0t鼠李糖脂发酵液 (RH)与其他表面活性剂进行复配 ,优选出了适合于大庆油田小井距的三元复合体系配方。通过对配方的综合性能评价 ,证明RH可以拓宽超低界面张力区域 ,降低表面活性剂的吸附滞留量 ,三元复合体系驱油效率比水驱提高 2 0 %以上。另外 ,在驱油效率相同的情况下 ,降低ORS41用量 5 0 % ,成本核算表明 ,生物表面活性剂三元复合体系成本比原三元复合驱矿场试验化学剂成本节省 30 %以上。     

Novel alkyl methylnaphthalene sulfonate surfactants: A good candidate for enhanced oil recovery

The surface tensions of various surfactant aqueous solution and the dynamic interfacial tensions between the Shengli oil field of China crude oil and the solution of novel surfactants, a series of single-component alkylmethylnaphthalene sulfonates (AMNS) including various the length of alkyl chains (hexyl, octyl, decyl, dodecyl and tetradecyl, developed in our laboratory), were measured. It is found that synthesized surfactants exhibited great capability and efficiency of lowering the solution surface tension. The critical micelle concentrations, CMC were: 6.1–0.018×10⁻³ mol L⁻¹, and the surface tensions at CMC, γ_CMC were: 28.27–35.06 mN m⁻¹. It is also found that the added surfactants are greatly effective in reducing the interfacial tensions and can reduce the tensions of oil–water interface to ultra-low, even 10⁻⁶ mN m⁻¹ at very low surfactant concentration without alkali. The addition of salt, sodium chloride, results in more effectiveness of surfactant in reducing interfacial tension and shows that there exist obviously both synergism and antagonism between the surfactant and inorganic salt. All of the synthesized surfactants, except for hexyl methylnaphthalene sulfonate, can reduce the interfacial tension to ultra-low at an optimum surfactant concentration and salinity. Especially Tetradec-MNS surfactant is most efficient on lowering interfacial tension between oil and water without alkaline and the other additives at a 0.002 mass% of very low surfactant concentration. Both chromatogram separation of flooding and breakage of stratum are avoided effectively, in addition to the less expensive cost for enhanced oil recovery, and therefore it is a good candidate for enhanced oil recovery.     

Novel fluorinated surfactants for enhanced oil recovery in carbonate reservoirs

Novel surfactant‐polymer (SP) formulations containing fluorinated amphoteric surfactant (surfactant‐A) and fluorinated anionic surfactant (surfactant‐B) with partially hydrolyzed polyacrylamide (HPAM) were evaluated for enhanced oil recovery applications in carbonate reservoirs. Thermal stability, rheological properties, interfacial tension, and adsorption on the mineral surface were measured. The effects of the surfactant type, surfactant concentration, temperature, and salinity on the rheological properties of the SP systems were examined. Both surfactants were found to be thermally stable at a high temperature (90 °C). Surfactant‐B decreased the viscosity and the storage modulus of the HPAM. Surfactant‐A had no influence on the rheological properties of the HPAM. Surfactant‐A showed complete solubility and thermal stability in seawater at 90 °C. Only surfactant‐A was used in adsorption, interfacial tension, and core flooding experiments, since surfactant‐B was not completely soluble in seawater and therefore was limited to deionized water. A decrease in oil/water interfacial tension (IFT) of almost one order of magnitude was observed when adding surfactant‐A. However, betaine‐based co‐surfactant reduced the IFT to 10^?3 mN/m. An adsorption isotherm showed that the maximum adsorption of surfactant‐A was 1 mg per g of rock. Core flooding experiments showed 42 % additional oil recovery using 2.5 g/L (2500 ppm) HPAM and 0.001 g/g (0.1 mass%) amphoteric surfactant at 90 °C.     

Enhanced oil recovery from high‐salinity reservoirs by cationic gemini surfactants

In order to enhance oil recovery from high‐salinity reservoirs, a series of cationic gemini surfactants with different hydrophobic tails were synthesized. The surfactants were characterized by elemental analysis, infrared spectroscopy, mass spectrometry, and ¹H‐NMR. According to the requirements of surfactants used in enhanced oil recovery technology, physicochemical properties including surface tension, critical micelle concentration (CMC), contact angle, oil/water interfacial tension, and compatibility with formation water were fully studied. All cationic gemini surfactants have significant impact on the wettability of the oil‐wet surface, and the contact angle decreased remarkably from 98° to 33° after adding the gemini surfactant BA‐14. Under the condition of solution salinity of 65,430 mg/L, the cationic gemini surfactant BA‐14 reduces the interfacial tension to 10^?3 mN/m. Other related tests, including salt tolerance, adsorption, and flooding experiments, have been done. The concentration of 0.1% BA‐14 remains transparent with 120 g/L salinity at 50 °C. The adsorption capacity of BA‐14 is 6.3–11.5 mg/g. The gemini surfactant BA‐14 can improve the oil displacement efficiency by 11.09%. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46086.     

毛管数对甜菜碱表面活性剂驱油效率的影响研究

为研究毛管数对甜菜碱表面活性剂驱油效率的影响,通过驱替实验研究了毛管数和驱油效率以及残余油饱和度之间的关系,结果表明,对于单一体系,无论是水、聚合物还是表面活性剂,其驱油效率均随着毛管数的增加而增加,残余油饱和度均随着毛管数的增加而降低。由于界面张力处于毛管力物理定义中的分母的位置,对毛管数的影响较大。界面张力越低,驱油效率越高,残余油饱和度越低,毛管数值越大。     

Enhancing Oil Recovery by Low Concentration of Alkylaryl Sulfonate Surfactant without Ultralow Interfacial Tension

Surfactant flooding plays a critical role in chemically enhanced oil recovery over the last half century, with the widely accepted mechanism of ultralow interfacial tension (IFT) by forming middle-phase microemulsions with high concentration of a lead surfactant and a cosurfactant. However, it is found practically from field trials that high oil recovery efficiency can be obtained from low concentration surfactant flooding without forming microemulsions, and the principle behind has not been clearly unraveled yet. Here the solubilization of paraffin oil by the micelles formed with a commercial enhanced oil recovery surfactant, raw naphthenic arylsulfonates (NAS), was investigated using ultraviolet-visible (UV–Vis) spectroscopy, dynamic light scattering (DLS), and transmission electron microscopy (TEM). It is found that paraffin oil can be well solubilized inside the NAS micelles, and mainly localized in the hydrophobic core of the micelles. The solubilization capacity of NAS micelles increases with increasing its concentration, and the size of micelles increases, but morphology of the micelles remains spherical with increasing the amount of paraffin oil, along with an appearance transition from transparent to opaque until the maximum solubilization capacity is reached. Core flooding results with crude oil indicate that in the presence of 0.24 wt.% polymer, addition of 0.1, 0.2, 0.5, and 1.0 wt.% NAS can get oil recovery factor of 24.1%, 27.0%, 30.5%, and 38.3%, which increases linearly with increasing NAS concentration though with the interfacial tension values only in the magnitude of 10⁻² mN m⁻¹ level. These findings prove preliminarily micellar solubilization can help increasing oil recovery efficiency even without ultralow IFT.     

Synthesis of an Alkyl Polyoxyethylene Ether Sulfonate Surfactant and Its Application in Surfactant Flooding

Surfactant flooding as a potential enhanced oil‐recovery technology in a high‐temperature and high‐salinity oil reservoir after water flooding has attracted extensive attention. In this study, the synthesis of an alkyl alcohol polyoxyethylene ether sulfonate surfactant (C₁₂EO₇S) with dodecyl alcohol polyoxyethylene ether and sodium 2‐chloroethanesulfonate monohydrate, and its adaptability in surfactant flooding were investigated. The fundamental parameters of C₁₂EO₇S were obtained via surface tension measurement. And the ability to reduce oil–water interfacial tension (IFT), wettability alteration, emulsification, and adsorption was determined. The results illustrated that IFT could be reduced to 10^?3 mN m^?1 at high temperature and high salinity without additional additives, and C₁₂EO₇S exhibited benign wettability alternate ability, and emulsifying ability. Furthermore, the oil‐displacement experiments showed that C₁₂EO₇S solution could remarkably enhance oil recovery by 16.19% without adding any additives.     

新型表面活性剂疏水缔合聚合物提高原油采收率的性能研究

介绍了渤海海上油田二元复合驱驱油的设计与开发方案,以新型表面活性剂(非离子型表面活性剂:DMES-14、TX-100)和疏水缔合聚丙烯酰胺(HAPAM)为主。二元复合驱驱油体系主要需要双子表面活性剂双十四酸乙二酯双磺酸盐型表面活性剂(DMES-14),疏水缔合聚丙烯酰胺以及取自海上油田平台的回注水。该体系同时对粘度和表面张力进行了研究。结果表明,该体系在不要求浓度的情况下可以达到超低界面张力2.48×10~(-3) m N/m,在油藏中粘度可达到55 m Pa;随后的岩心驱替试验表明,在水驱含水75%的状况下进行二元复合驱驱油效果可提高至38.6%以上。总之,该实验研究提供了非离子表面活性剂与疏水缔合水溶性聚合物驱油体系的实用信息以及可以在渤海海上油田进行大规模应用HAPAM。     

十八烷基己基甲基羧基甜菜碱的合成及性能

以硬脂酸和己酸为原料合成了不对称双长链烷基羧基甜菜碱——十八烷基己基甲基羧基甜菜碱(C18+6B),测定了C18+6B的表面活性,并与总碳原子数相等的对称型双十二烷基甲基羧基甜菜碱(di C12B)进行比较,以了解表面活性剂分子结构对性能的影响。结果表明,C18+6B的表面活性与di C12B基本相当,但水溶性远好于di C12B。作为无碱驱油用表面活性剂,C18+6B对大庆原油来说HLB值略偏高,45℃下单独使用能将大庆原油/地层水界面张力降至10-2m N/m数量级,在大庆油砂上的饱和吸附量比di C12B低30%。C18+6B单独能将C7~C9正构烷烃/大庆地层水界面张力降至10-3m N/m数量级,而通过与亲油性更强的di C12B以及亲水性甜菜碱复配后,能将大庆原油/地层水界面张力降至10-3m N/m数量级,并能显著改善配方的水溶性。     

十八烷基己基甲基羧基甜菜碱的合成及性能

以硬脂酸和己酸为原料合成了不对称双长链烷基羧基甜菜碱——十八烷基己基甲基羧基甜菜碱(C18+6B),测定了C18+6B的表面活性,并与总碳原子数相等的对称型双十二烷基甲基羧基甜菜碱(diC12B)进行比较,以了解表面活性剂分子结构对性能的影响。结果表明,C18+6B的表面活性与diC12B基本相当,但水溶性远好于diC12B。作为无碱驱油用表面活性剂,C18+6B对大庆原油来说HLB值略偏高,45 ℃ 下单独使用能将大庆原油/地层水界面张力降至10-2mN/m数量级,在大庆油砂上的饱和吸附量比diC12B低30%。C18+6B单独能将C7~C9正构烷烃/大庆地层水界面张力降至10-3mN/m数量级,而通过与亲油性更强的diC12B以及亲水性甜菜碱复配后,能将大庆原油/地层水界面张力降至10-3mN/m数量级,并能显著改善配方的水溶性。     

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.     

Viscoelastic Surfactants with High Salt Tolerance,Fast‐Dissolving Property,and Ultralow Interfacial Tension for Chemical Flooding in Offshore Oilfields

Injected chemical flooding systems with high salinity tolerance and fast‐dissolving performance are specially required for enhancing oil recovery in offshore oilfields. In this work, a new type of viscoelastic‐surfactant (VES) solution, which meets these criteria, was prepared by simply mixing the zwitterionic surfactant N‐hexadecyl‐N,N‐dimethyl‐3‐ammonio‐1‐propane sulfonate (HDPS) or N‐octyldecyl‐N,N‐dimethyl‐3‐ammonio‐1‐propane sulfonate (ODPS) with anionic surfactants such as sodium dodecyl sulfate (SDS). Various properties of the surfactant system, including viscoelasticity, dissolution properties, reduction of oil/water interfacial tension (IFT), and oil‐displacement efficiency of the mixed surfactant system, have been studied systematically. A rheology study proves that at high salinity, 0.73 wt.% HDPS/SDS‐ and 0.39 wt.% ODPS/SDS‐mixed surfactant systems formed worm‐like micelles with viscosity reaching 42.3 and 23.8 mPa s at a shear rate of 6 s^?1, respectively. Additionally, the HDPS/SDS and ODPS/SDS surfactant mixtures also exhibit a fast‐dissolving property (dissolution time <25 min) in brine. More importantly, those surfactant mixtures can significantly reduce the IFT of oil–water interfaces. As an example, the minimum of dynamic‐IFT (IFT_min) could reach 1.17 × 10^?2 mN m^?1 between the Bohai Oilfield crude oil and 0.39 wt.% ODPS/SDS solution. Another interesting finding is that polyelectrolytes such as sodium of polyepoxysuccinic acid can be used as a regulator for adjusting IFT_min to an ultralow level (<10^?2 mN m^?1). Taking advantage of the mobility control and reducing the oil/water IFT of those surfactant mixtures, the VES flooding demonstrates excellent oil‐displacement efficiency, which is close to that of polymer/surfactant flooding or polymer/surfactant/alkali flooding. Our work provides a new type of VES flooding system with excellent performances for chemical flooding in offshore oilfields.     

Synthesis of Didodecylmethylcarboxyl Betaine and Its Application in Surfactant–Polymer Flooding

Enhanced crude oil recovery by chemical flooding has been a main measure for postponing the overall decline of crude oil output in China, and surfactant-polymer (SP) flooding may replace alkali-surfactant-polymer flooding in the future for avoiding the undesired effects of using alkali. In this paper the synthesis of a surfactant with a large hydrophobe, didodecylmethylcarboxyl betaine (diC₁₂B), and its adaptability in SP flooding were investigated. The results show that diC₁₂B can be synthesized by reaction of didodecylmethyl amine, a product commercially available, with chloroacetic acid in the presence of NaOH, with a resulting yield as high as 80?wt% under appropriate conditions. With double dodecyl chain diC₁₂B is highly surface active as displayed by its low CMC, 3.7?×?10^?6?mol?L^?1, low ??_CMC, 27?mNm^?1, as well as high adsorption and small cross section area (??0.25?nm²) at both air/water and oil/water interfaces at 25?°C. By mixing with conventional hydrophilic surfactants diC₁₂B can be well dissolved in Daqing connate water and reduce the Daqing crude oil/connate water interfacial tension to about 10^?3?mN?m^?1 at 45?°C in a wide total surfactant concentration range, from 0.01 to 0.5 wt%. And a tertiary oil recovery, 18?±?1.5?% OOIP, can been achieved by SP flooding using natural cores without adding any alkaline agent or neutral electrolyte. DiC₁₂B seems thus to be a good surfactant for enhanced oil recovery by SP flooding.     

Effects of Polyether Surfactants on Dynamic Interfacial Tension of Betaine Solutions against Crude Oil

The dynamic interfacial tension (IFT) of betaine and betaine/polyether‐nonionic surfactant‐mixed systems against hydrocarbons, kerosene, and crude oil–water was studied using a spinning‐drop tensiometer. The influence of average molecular weight of polyether‐nonionic surfactants on IFT of mixed solutions was investigated. On the basis of the experimental results, one can find that it is difficult to reach the ultralow IFT value for betaine solution against hydrocarbon and kerosene because of the mismatch between the hydrophobic and hydrophilic groups. After purification, kerosene still contains a small amount of carboxyl groups, which can exert a synergistic effect on surfactants resulting in a lower IFT. The IFT of betaine and mixtures against Daqing crude oil can reach an ultralow value because of the mixed adsorption of surfactant and petroleum soap molecules. For mixed solutions, with the increasing concentration of added polyether, the decrease of petroleum soaps at the oil–water interface results in the destruction of synergistic effects.     

新型弱碱表面活性剂在三次采油中的应用

以α-烯烃为初始原料，经过烷基化，再经磺化、中和研制出了组分相对单一、结构合理的新型弱碱烷基苯磺酸盐表面活性剂。室内评价结果表明，该表面活性剂具有良好的界面活性，配制的复合体系在较宽的表面活性剂浓度和碱浓度范围可与原油形成10^-3mN／m数量级的超低界面张力。同时，该表面活性剂对大庆油田不同区块、不同油层的油水条件表现出了很强的适应性。另外，由于表面活性剂组成较为单一，可大大降低表面活性剂在地层中因吸附滞留而产生的色谱分离效应。室内天然岩心驱油实验表明，三元复合体系平均驱油效率可比水驱提高约20％。所开展的小井距三元复合驱矿场试验，取得了比水驱提高采收率24．66％的显著效果，为三元复合驱技术在大庆油田的工业化推广，特别是在二类油层的应用奠定了坚实基础。     

辛基酚聚氧乙烯醚烷基磺酸钠溶液的性能研究

对非离子-阴离子型表面活性剂辛基酚聚氧乙烯醚(10)烷基磺酸钠(OPS-10)的溶液性能进行了研究。用表面张力法测定OPS-10的CMC为65 mg/L;在85℃、无机盐离子浓度90 000 mg/L的水溶液中,OPS-10表现出了良好的抗温抗盐性;动态界面张力研究显示,OPS-10降低油-水动态界面张力的曲线呈"L"型,平衡值达到10-2数量级;室内驱替实验表明,对于特低渗透率的岩心,OPS-10可以在水驱的基础上提高驱油效率2.89%,优于十二烷基苯磺酸钠的驱替效果。基于在上述方面表现的良好性能,OPS-10可以作为驱油剂或助剂进行高矿化度水和高温油藏的驱油实验研究和应用。     

Numerical simulation of enhanced oil recovery studies for aqueous gemini surfactant-polymer-nanoparticle systems

The article investigates the efficacy of gemini surfactant/polymer/nanoparticle flooding on chemical EOR. Initially, physicochemical behavior of aqueous chemical fluids were investigated via interfacial tension reduction, wettability alteration, adsorption, viscosity moderation and oil displacement experiments. During compositional analysis, Cartesian model with specified grid properties, injection flow-rate, well pattern, and rock-fluid characteristics was developed using CMG-STARS tool. Contour map analyses showed that oil saturation decreased from ~80% (initial) to 31.96%, 30.68%, and 29.30% after {14-6-14 GS + chase water}, {14-6-14 GS + PHPA + chase water}, and {14-6-14 GS + PHPA + SiO₂ chase water} flooding respectively. Tertiary recoveries of 15–19% were achieved, depending on injected fluid composition. Experimental data were history matched via CMOST tool to achieve good matching of simulated results. The CMG flooding simulator provides a holistic approach to investigate oil displacement profiles, assess flooding recovery capabilities with near-accuracy and predict the feasibility of proposed chemical EOR projects.     

From Phase Behavior to Understand the Dominant Mechanism of Alkali-Surfactant-Polymer Flooding in Enhancing Heavy Oil Recovery

The primary objective of this work was to understand the dominant mechanism(s) of alkali‐surfactant‐polymer (ASP) flooding in enhancing heavy oil recovery. Chemical formulations were first optimized based on phase behavior studies. The data indicated that alkali and surfactant created a synergistic effect at the oil/water interface, which further decreased the interfacial tension (IFT) and improved the emulsification. However, it was also found that the addition of alkali was detrimental to the viscous properties of the chemical systems and caused the ultimate oil recovery to decrease. In other words, the macroscopic sweep efficiency as a result of viscosity was the primary factor determining the overall recovery of heavy oil followed by emulsification, which was verified by the phase behavior of the effluent. Based on the experimental results, we found that for this targeted heavy oil reservoir, surfactant‐polymer (SP) flooding was more appropriate than ASP flooding and it was not necessary to decrease the IFT to the ultralow level (10^?3 mN/m) using alkali. Through chemical flooding, the incremental oil recovery was increased up to 27% of original oil in place, indicating the potential of this technique in heavy oil reservoirs.