显色反应法检测双子季铵盐缓蚀剂残余浓度

利用显色反应法检测油田用双子季铵盐缓蚀剂的残余浓度,以百里香酚蓝为显色剂,经过反复实验确定了最佳显色剂用量为0.4%、NH₄Cl-NH₃缓冲溶液用量为10 mL、显色时间为60 min,得到甲硝唑改性不对称双子季铵盐（季铵盐-01）吸光度与浓度标准曲线用于测定缓蚀剂浓度。同时,还研究了干扰离子、聚丙烯酰胺、含油量对检测结果的影响。该测试方法可靠准确性高,其平均加标回收率达到98.6%,可在油田现场进行推广。当Ca²⁺<4000 mg/L,Mg²⁺<1800 mg/L,Fe³⁺<1.5 mg/L时,该检测方法的误差<5%。当PAM（相对分子质量50万）浓度小于200 mg/L时,吸光度与缓蚀剂浓度仍能呈线性关系。污水中原油对检测结果的影响较大。     

蒙脱石-CO2溶液反应实验研究

蒙脱石是沉积岩重要的黏土矿物,为探究CO₂的注入对蒙脱石产生的影响,明确蒙脱石在CO₂水溶液中的 化学行为,利用XRD、XRF、ICP 等手段系统评价了蒙脱石在10 MPa、60 ℃条件下分别与CO₂反应7、30 d 时的状 态,重点对比了蒙脱石粉末反应前后固相元素、晶体结构及反应液中离子浓度变化,结合蒙脱石结构特征,明确 蒙脱石在酸中变化的机理。结果表明,蒙脱石与CO₂反应后液相中Ca²⁺ 、Mg²⁺ 、Al³⁺ 浓度先上升后下降;Si⁴⁺ 浓度先 上升后趋于平稳,固相中d（001）对应晶面在溶解反应后遭到破坏。相对于Al³⁺ 、Si⁴⁺,反应过程中Mg²⁺、Ca²⁺、Na⁺ 的变动幅度相对较大。一方面,由于蒙脱石阳离子交换容量较大,层间Na⁺、Mg²⁺、Ca²⁺等半径较大的活性阳离子 易被半径较小的H⁺置换出;另一方面,蒙脱石层间分子间作用力为范德华力,相对于静电力较弱,结构易被破 坏。在酸性条件下,硅氧四面体稳定性略强于铝氧八面体,但蒙脱石中非晶态Si 易溶解,使Si 的变化幅度大于 Al 的变化幅度。     

阳离子对 HPAM/Cr3+弱凝胶性能的影响

为揭示相同价态阳离子对弱凝胶成胶性能的影响规律, 研究了 Mg²⁺、 Ca²⁺、 Na⁺、 K⁺四种常见阳离子对部分水解聚丙烯酰胺（HPAM） /Cr³⁺弱凝胶成胶黏度和稳定性的影响。结果表明, 阳离子浓度过低或过高均会抑制HPAM/Cr⁺体系的成胶; HPAM质量浓度为3 g/L时, 利于HPAM成胶的单一阳离子浓度适宜范围分别为Mg²⁺ 0.4～9 g/L、 Ca²⁺ 1.2～18 g/L、 Na⁺ 9～30 g/L、 K⁺ 16～55 g/L; 阳离子半径越小、 对凝胶成胶黏度和稳定性的影响越大; 四种阳离子对弱凝胶成胶黏度的影响顺序为Mg²⁺>Ca²⁺>Na⁺>K⁺, 对弱凝胶稳定性的影响顺序为Mg²⁺>Ca²⁺、 Na⁺>K⁺。图3参12     

二氧化碳驱后微粒运移对低渗透储层的伤害及对渗流能力的影响

CO₂驱是高含水油藏三次采油有效的技术措施。利用现有井网转注CO₂是目前低油价下经济可行的开发 方式。虽然在驱替过程中引起的微粒运移会对岩石孔喉造成堵塞,但注入CO₂能有效降低注入压力,且在注入 过程中发生的溶蚀作用整体上提高了流体的渗流能力。通过开展CO₂驱后微粒运移堵塞规律实验及CO₂-水溶 液对岩石溶蚀评价实验,并对驱替前后的相渗曲线变化特征进行评价,进一步说明CO₂驱对储层渗流能力的影 响。结果表明,在注入CO₂的过程中,注入速度为0.1、1.0 mL/min时的注入压力均有所降低。有油条件下CO₂驱 后的岩心渗透率损失为37.05%,而经甲苯和无水乙醇清洗岩心后,岩心渗透率恢复30.48%,说明微粒在运移过 程中会被原油束缚,积聚成团,造成堵塞。虽然存在一定的堵塞,但CO₂-水溶液主要与绿泥石发生反应,并释放 Ca²⁺、Mg²⁺、Fe²⁺等离子,其中Ca²⁺浓度增长137.05%、Mg²⁺浓度下降52.20%、Fe²⁺浓度下降49.45%,说明虽然产生的MgCO₃、Fe₂O₃等会对岩石孔喉造成堵塞,但CO₂对CaCO₃的溶蚀作用更强,整体上提高了流体的渗流能力,从而 在一定程度上改善了后续水驱的注水能力及效果。CO₂驱前后,相渗曲线中束缚水饱和度增加,残余油饱和度降 低,两相共渗区增大,驱油效率增加,进一步说明CO₂驱产生的溶蚀作用整体上增大了孔隙空间和渗流通道,提 高了注入水的注入能力。     

驱油用超高分子量聚丙烯酰胺拉伸流变性能研究

聚合物溶液的流变行为对其在油藏多孔介质中的驱油效果影响较大。系统分析了聚合物含量、温度、多种金属离子及机械剪切作用对驱油用超高分子量部分水解聚丙烯酰胺(U-HPAM)及常规中等分子量部分水解聚丙烯酰胺(M-HPAM)溶液拉伸流变性能的影响。实验结果表明:提高聚合物含量能够促进HPAM分子链间纠缠,聚合物的拉伸黏度增加,同时U-HPAM对拉伸黏度的增强幅度远大于M-HPAM;温度升高、外加金属离子(Na⁺、Ca²⁺、Mg²⁺、Fe³⁺和Fe²⁺)含量增大及机械剪切作用增强都会削弱聚合物分子链间纠缠,导致拉伸黏度降低;U-HPAM受温度及Na⁺、Ca²⁺、Mg²⁺、Fe³⁺等的影响明显小于M-HPAM,而Fe²⁺及机械剪切对两类HPAM影响程度相似。渗流及岩心驱替实验表明,U-HPAM比M-HPAM具有更强的调剖能力,在强非均质油藏中更能发挥其高效驱油能力。      

NaAlO2溶液中铝酸根离子的微观结构

 应用IR、²⁷Al NMR 和UV3种波谱方法对不同方式配制的Al₂O₃浓度和苛性系数基本相同的四种NaAlO₂溶液进行了详细的表征。结果表明IR、²⁷Al NMR和UV3种光谱方法给出的信息可以相互补充支持,共同给出NaAlO₂溶液中铝酸根离子的微观结构。溶液配制方式对NaAlO₂溶液中铝酸根离子的微观结构具有显著影响,4种NaAlO₂溶液中铝酸根均以四配位[Al(OH)₄]^-为主体离子,可以排除六配位[Al(OH)₆]^3-的存在; 二聚[Al₂O(OH)₆]^2-含量因配制方式不同存在显著差别,在方式Ⅰ配制的溶液中二聚[Al₂O(OH)₆]^2-含量很少或不存在,在方式Ⅱ、Ⅲ、Ⅳ配制的溶液中显著存在二聚[Al₂O(OH)₆]^2-,在溶液Ⅱ、Ⅲ中还存在尚未确定结构的离子。     

阴-非离子型表面活性剂CO2 泡沫影响因素研究

选用4 种表面活性剂作为起泡剂,其中N-NP-15c 和N-NP-21c 为非离子型表面活性剂,N-NP-15c-H 和N-NP-21c-H 为新合成的阴- 非离子型表面活性剂,非离子基团为聚氧乙烯基,阴离子基团为磺酸基。利用高温高压搅拌式可视化泡沫仪,对表面活性剂进行高温高压和高盐条件下的CO₂ 泡沫性能测试;研究了不同因素对CO₂泡沫性能的影响规律,包括起泡剂浓度、矿化度、Ca²⁺浓度、温度和压力等。实验结果表明,N-NP-15c-H 的起泡性能最好,抗温达125℃ 。在起泡剂质量分数0.7% 、压力10MPa、矿化度（NaCl）50g/L、125℃ 时,泡沫的起泡体积和半衰期分别为81.6 mL和10.8 min。随着起泡剂质量分数的增大,CO2 泡沫的起泡体积和半衰期均先增大后减小,最佳加量为0.7% ;高温和高矿化度（高Ca²⁺浓度）都不利于CO₂ 泡沫的稳定;压力升高则能显著提高CO₂ 泡沫的性能,压力由5 MPa 增至12MPa 时,泡沫起泡体积由87.9 mL增至165.8 mL,半衰期由34.5 min增至295.2min。     

APEC(Na)降低油水界面张力影响因素研究

在埕岛油田埕北油水条件下,考察了烷基酚聚氧乙烯醚羧酸钠(APEC(Na)) 阴非离子表面活性剂乙氧基（EO）数、温度、无机盐、溶液pH值对油水界面张力的影响。结果表明,APEC(Na)中的EO数为6时的油水界面张力最低6.5×10^-3 mN/m。温度由30℃增至80℃,0.3%的APEC(Na) （EO数=6）海水溶液与埕北原油间的界面张力由5.6×10^-2 mN/m降至6.4×10^-3 mN/m;在APEC(Na)完全溶解后,温度（50~80℃）对界面张力的影响不明显。单一NaCl、Na2SO4、NaHCO3、CaCl2、MgCl2无机盐对APEC(Na)降低油水界面张力产生影响。随无机盐浓度升高,界面张力均先降低后升高;阳离子类型对界面张力的影响强于阴离子类型。Na₂SO₄、MgCl₂、CaCl₂加量分别为25×10⁴、10×10⁴、25×10⁴ mg/L时,界面张力最低,分别为1.2×10^-3、2.2×10^-3、5.8×10^-3mN/m,Mg²⁺对APEC(Na)界面活性的影响最大。在APEC(Na)海水溶液中加入1% NaOH,EO数为7的APEC(Na)可使原油界面张力达到最低值2.9×10^-3 mN/m;随EO数为7的APEC(Na)海水溶液pH值升高,油水界面张力先降低后升高,pH值为13.4（NaOH加量1%）时的界面张力最低。     

Fe 3+x-TiO2/Shell光催化剂的制备及其对石油的光催化降解

 以自制的贝壳基规整吸附体为载体,采用浸渍煅烧法制备了Fe ³⁺_x-TiO₂/Shell光催化剂。采用XRD、SEM-EDS和UV-Vis等技术对制备的Fe ³⁺_x-TiO₂/Shell光催化剂进行表征。以石油为降解对象,考察了Fe³⁺掺杂量、Fe ³⁺_x-TiO₂/Shell的负载次数及光照时间对Fe ³⁺_x-TiO₂/Shell光催化活性的影响。结果表明,Fe³⁺掺杂量为0.7%(m(Fe³⁺ )/m(TiO₂)×100%)、Fe ³⁺_0.7-TiO₂负载次数为4次时,制备的Fe ³⁺_0.7-TiO₂/Shell光催化剂的光催化活性最高,300 W碘钨灯照射16 h,石油的光催化降解率达76%。     

海水中瓜尔胶溶胀性能研究

针对海上连续混配海水基压裂液过程中稠化剂溶胀问题,开展了瓜尔胶溶胀性能的研究。考察了瓜尔胶取代基类型、取代度、搅拌速度、瓜尔胶加量、pH值和温度对瓜尔胶溶胀性能的影响。结果表明,我国某海域海水水样矿化度为34440 mg/L,富含Na⁺、Mg²⁺、Ca²⁺和Cl^-、SO₄^2-。在常规条件下（20℃、300 r/min、pH=7.5）,羧甲基瓜尔胶、羟丙基瓜尔胶（取代度0.30）、羟丙基瓜尔胶（取代度0.15）、未改性瓜尔胶在海水中的溶胀时间分别为25、50、55、60 min,对应的表观黏度分别为63、59、45、23 mPa·s。以羧甲基瓜尔胶为研究对象,考察其他因素对溶胀性能的影响。优选的配制方案为：搅拌速度400~500 r/min、温度30~40℃、pH值6~7,瓜尔胶加量0.5%以内。溶胀时间能控制在10 min以内,满足连续混配海水基压裂液施工要求。     

The surface wettability of brine in a tight oil reservoir

Based on DSA100 instrumentation, the interactions between the chemical groups on the rock surface and brine were analyzed to study the abilities and microscopic mechanisms on reservoir characteristics of wettability controlled by Na⁺, Ca²⁺and Mn²⁺. The results show that that in the same solution, static and dynamic angle of each ions are consistent. When the concentration of CaCl₂ solution is more than 0.5 mol/L, the contact angle will change greatly. Ca²⁺, Mn²⁺ can change the structural characteristics of tight reservoirs. This provides a theoretical basis for our study of low salinity water flooding and recovery ratio.     

新型驱油用表面活性剂天然混合羧酸盐

本文是一篇专论，介绍了天然混合羧酸盐的原料(油脂下脚料)，界面活性及抗二价离子的能力，简述了ASP三元复合驱油体系配方筛选方法，介绍了针对我国不同酸值原油研制的含天然混合羧酸盐的3个ASP典型配方。     

强碱三元复合驱硅结垢特点及防垢措施研究

对三元复合驱油井垢样的外貌特征和成分进行了分析,采用模拟采出液,在室内研究了单纯硅体系;钙、镁、硅离子共存;钙、镁、铝、硅离子共存;钙、镁、铝、聚丙烯酰胺及硅共存;钙、镁、铝、表面活性剂及硅共存;钙、镁、铝、聚丙烯酰胺、表面活性剂及硅共存等6个体系。这6个体系中硅离子的结垢特点表明,硅结垢的形态和过程受上述6种体系中其他离子影响严重。三元复合驱中垢的粘附性高于普通垢,对螺杆泵和抽油机有较大的影响。采取小过盈螺杆泵、防垢泵、井下固体化学等防垢技术措施,现场应用取得了明显的效果。     

Seawater-softening process through formation of calcite ooids

Conventional water-softening processes usually involve the exchange of Na⁺ ions for Ca²⁺ and Mg²⁺ using commercial or synthesized ion exchangers. The differences in chemical compositions of the ooids can be attributed to the formation in different environments. In this paper, ooid grains form inside assembled semi-pilot softening unit through a continuous chemical process involving reaction between bicarbonate ions and added lime using natural seawater. Our sample of Mediterranean seawater has low Mg²⁺/Ca²⁺ ratio (1.98%) within the range chemically favorable for precipitation of low-Mg calcite ooids. Precipitation of calcite occurs around pure quartz sand grains which act as nucleation points (the bed required for sand vessel is 1.65 l). The shape of the sand grains controls the overall external morphology of the resulting ooids; they vary in size from 0.5 to 3.0 mm and have a high degree of polish due to surface abrasion caused by continuous agitation inside the softening system. Calcite ooid grains (1.53 kg) formed within the seawater-softening unit every 18 days have many of the ooid features formed in marine environments. Ooids grow to a significant size, at a rate of about 0.17 mm of one layer thickness per day inside the softening unit. The average weight percent of calcite precipitate is 35.48% after 18 days, at 10 °C, 60 l/min and pH 9.0. The pellets comprise mainly CaCO₃ and SiO₂ and some metal ions which may substitute for calcium ions in calcite are present only in trace amounts of the total composition.     

Effect of pH and scale inhibitor concentration on phosphonate–carbonate interaction

In this paper, we present results from five corefloods (RC1 to RC5) from the Jurassic Portlandian limestone (ф ~ 19.80% and k = 606 mD) using 5000 ppm, 10,000 ppm, 25,000 ppm and 27,000 ppm of partly neutralized Diethylenetriamine pentamethylenephosphoric acid (DETPMP) at pH 4 and 2. The purpose of this study was to study the effect of inhibitor concentration and pH on the inhibitor adsorption and on the evolution of the inhibitor and cation (calcium and magnesium) return concentrations. These corefloods were performed using long cores (12 in.), which were treated with just 0.5 pore volume (PV) of inhibitor. Another purpose was to study the transport and inhibitor/carbonate rock interactions when less than 1 PV of inhibitor solution is injected. This allows for consumption of the inhibitor during propagation and return, rather than saturating the core with many PV to full adsorptive capacity of the inhibitor/rock system. This study showed that the higher the concentration of SI and lower the pH, the more calcium dissolution is observed (from the [Ca²⁺] effluents). In all treatments there is a decrease in the [Mg²⁺] effluent corresponding directly to the increase in calcium. The effluent cation results in the long corefloods which strongly support the view that both magnesium and calcium are binding quite strongly to the DETPMP scale inhibitor. These observations lead us to a number of conclusions on the factors that must be included in a full carbonate model. In particular, our experimental results, along with some simple modeling, greatly clarify the role of both calcium and magnesium in the mechanism of the scale inhibitor retention in carbonate systems.     

Use of natural geochemical tracers to improve reservoir simulation models

This article introduces a methodology for integrating geochemical data in reservoir simulations to improve hydrocarbon reservoir models. The method exploits routine measurements of naturally existing inorganic ion concentration in hydrocarbon reservoir production wells, and uses the ions as non-partitioning water tracers. The methodology is demonstrated on a North Sea field case, using the field's reservoir model, together with geochemical information (SO₄²⁻, Mg²⁺, K⁺, Ba²⁺, Sr²⁺, Ca²⁺ and Cl⁻ concentrations) from the field's producers. Based on the dataset, some of the ions are shown to behave almost as ideal seawater tracers, i.e. without sorption to the matrix, ion exchange with the matrix or scale formation with other ions in the formation water. Moreover, the dataset shows that ion concentrations in pure formation water vary according to formation. This information can be used to allocate produced water to specific water-producing zones in commingled production. Based on an evaluation of the available data, one inorganic component, SO₄²⁻, is used as a natural seawater tracer. Introducing SO₄²⁻ as a natural tracer in a tracer simulation has revealed a potential for improvements of the reservoir model. By tracking the injected seawater it was possible to identify underestimated fault lengths in the reservoir model. The demonstration confirms that geochemical data are valuable additional information for reservoir characterization, and shows that integration of geochemical data into reservoir simulation procedures can improve reservoir simulation models.     

A chemical induced enhanced weakening of chalk by seawater

The objective of the present study is to provide a better understanding about the mechanism for weakening of chalk reservoirs when injecting large quantities of seawater to improve the oil recovery. The mechanical stability of chalk has often been related to capillary forces, which is known to induce an apparent cohesion between chalk grains, although several researchers have pointed out that other mechanisms need to be considered as well. In the present study, the experimental conditions have been designed to quantify the weakening of the chalk in a chemical dissolution/precipitation process, when one of the common ions, Ca²⁺ or CO₃²⁻, was chemically removed from the solution at 130 °C during an aging time of 6 weeks. Removal of one of the common ions enhances the dissolution of chalk. Three different saturating fluids were used: (1) artificial Ekofisk formation brine (EF-brine), (2) artificial seawater (SSW), and (3) modified seawater containing 4 times the sulphate concentration with respect to artificial seawater (SSW1). At the aging conditions, CaSO₄(s) was about to precipitate from the SSW1 solution, causing dissolved Ca²⁺ ions from the chalk to be precipitated/removed as CaSO₄(s) from the solution. No removal of common ions took place using EF-brine and SSW. Mechanical tests (Brazilian tests, hydrostatic yield, and K-modulus) at room temperature of the chalk cores saturated with the actual fluids showed that the strength of chalk saturated with SSW1 was 20–25% weaker than cores saturated with EF-brine and SSW. No difference in chalk strength was detected using EF-brine and SSW. The greater water weakening of cores saturated with SSW1 was discussed in terms of a chemical dissolution/precipitation process and the chemistry of the thin water film close to the intergranular contacts.     

污水配制聚合物溶液增黏措施与机理研究

本文通过正交试验分析胜利油田埕东污水造成配制聚合物溶液黏度降低的主要因素,研制提高污水配聚增黏的处理配方体系。经处理后污水配制的聚合物溶液初始黏度由12.0 m Pa·s提高到32.0 m Pa·s,增黏率达到167%;通过原子力显微镜(AFM)和动态光散射(DLS)对聚合物溶液微观形貌及聚集体粒径观察,分析配方的增黏机理:一方面,氢氧化钠沉淀Fe2+,消除了Fe2+对聚合物聚集体的破坏作用;AFM和DLS显示聚合物溶液聚集体粒径由80.5 nm增加到159.9 nm。另一方面,离子屏蔽剂可屏蔽Ca2+、Mg2+从而减弱了Ca2+、Mg2+对聚合物分子链的卷曲作用;AFM和DLS显示屏蔽剂使聚合物溶液聚集体的粒径由160.1 nm增大到208.5 nm。     

Injection of seawater and mixtures with produced water into North Sea chalk formation: Impact of fluid–rock interactions on wettability and scale formation

Seawater has been injected into high temperature and natural fractured North Sea chalk reservoirs to improve oil recovery with great success. Previous studies have shown that seawater will improve the water wetness and cause enhanced compaction of the matrix. The composition of the produced water will be quite similar to initial formation water at the start of the water injection. The formation water contains various amounts of divalent cations like Mg²⁺, Ca²⁺, Sr²⁺, and Ba²⁺. Later on, the composition will change due to the interaction between seawater and the chalk formation and some mixing with formation water. The fluid–rock interaction will involve dissolution of CaCO₃, substitution of Ca²⁺ by Mg²⁺ at the chalk surface, precipitation of CaSO₄, SrSO₄ and BaSO₄ depending on the reservoir temperature. Because of environmental reasons, it is desirable to re-inject produced water together with seawater. In the forthcoming research, we will study experimentally the effect of this re-injection on oil recovery and chalk compaction by using mixtures of produced water and seawater as injection fluid. Based on model studies using the OLI software package, the compatibility of mixtures of produced water and seawater has been studied at different temperatures by looking at the precipitation of CaSO₄, SrSO₄ and BaSO₄. Also the impact of changes in the concentrations of Ca²⁺ and Mg²⁺ due to surface substitution is modelled. The results are discussed in terms of possible scale formation in the producer and injector. In addition, actual chemical equilibrium reactions in the chalk matrix are discussed in relation to variation in temperature during continuous injection of seawater. Special focus is made on wettability modification, irreversible thermodynamics, and impact on the mechanical strength of the chalk matrix.