Hydroxysulfobetaine/Hydrolyzed Polyacrylamide Complex Systems for Gudao Heavy Oil Recovery: A Dynamic Interfacial Tension Study

Abstract

A complex system that consists of hydroxysulfobetaine and hydrolyzed polyacrylamide has been studied. It is indicated that the complex system is of high viscosity and can reduce the interfacial tension between Gudao heavy oil and solution to ultra-low value. The interfacial tension of complex system in formation water is influenced simultaneously by the concentration of polymer and the salt content. The adsorption experiment shows that hydrolyzed polyacrylamide can prevent hydroxysulfobetaine from being adsorbed on the quartz sands excessively. It can be concluded that the hydroxysulfobetaine/hydrolyzed polyacrylamide complex system is capable of satisfying the requirements of displacement system for EOR.     

近井地带剪切作用对驱油用聚合物溶液渗流特性的影响

在前人的工作基础上设计了一个近井地带剪切模拟装置,选用两种较为典型的聚丙烯酰胺类聚合物——部分水解聚丙烯酰胺(HPAM)和疏水缔合聚丙烯酰胺(HAPAM)进行室内实验,研究两种聚合物溶液经剪切后的渗流特性。实验结果表明：随着吸水强度的增加,两种浓度为1750 mg/L的聚合物溶液的黏度和黏度保留率快速下降。由于自身的疏水缔合作用,HAPAM溶液剪切后具有高于HPAM溶液的黏度及黏度保留率。在吸水强度10 m³/(m·d)和20 m³/(m·d)条件下剪切两种聚合物溶液,经剪切后的HAPAM溶液的阻力系数和残余阻力系数远大于HPAM溶液的,HAPAM溶液的阻力系数损失率小于HPAM溶液,而残余阻力系数损失率大于HPAM溶液。经剪切后的HAPAM溶液具有更高的驱油效率,剪切后HAPAM的溶液原油采收率损失略高于HPAM溶液的。     

Study of action mechanisms and properties of Cr3+ cross-linked polymer solution with high salinity

Performance characteristics of partially hydrolyzed polyacrylamide (HPAM) and cross-linked polymer (CLP, Cr 3+ as the cross linker) solutions have been investigated. A Brookfield viscometer, rheometer, dynamic light scattering system, and core flow device have been used to measure the viscosity, viscoelasticity, polymer coil dimensions, molecular configuration, flow characteristics, and profile modification. The results show that, under conditions of high salinity and low HPAM and Cr 3+ concentrations, cross-linking mainly occurred between different chains of the same HPAM molecule in the presence of Cr 3+ , and a cross-linked polymer (CLP) system with a local network structure was formed. Compared with an HPAM solution of the same concentration, the apparent viscosity of the CLP solution increased slightly or remained almost unchanged, but its viscoelasticity (namely storage modulus, loss modulus, and first normal stress difference) increased, and the resistance coefficient and residual resistance coefficient increased significantly. This indicates that the CLP solution exhibits a strong capability to divert the sequentially injected polymer flood from high-permeability zones to low-permeability zones in a reservoir. Under the same HPAM concentration conditions, the dimensions of polymer coils in the CLP solution increased slightly compared with the dimensions of polymer coils in HPAM solution, which were smaller than the rock pores, indicating that the cross-linked polymer solution was well adapted to reservoir rocks. Core flood experiments show that at the same cost of reagent, the oil recovery by CLP injection (HPAM-1, Cr 3+ as the cross linker) is 3.1% to 5.2% higher than that by HPAM- 2 injection.     

影响聚合物驱矿场实施效果的几个问题

通过对胜利油区聚合物驱项目矿场实施状况及增油效果的分析,研究了影响聚合物矿场实施效果的几个主要问题,提出了提高聚合物驱矿场运行质量的主攻措施。     

双河油田IV5－11 层系复合驱油体系实验研究

根据双河油田IV5-11层系的油藏特征,利用正交实验法,对聚合物质量浓度、表面活性剂种类及其质量分数进行筛选,得到了由质量浓度为1500mg/L的ZL-Ⅱ、质量分数为0.3%的QY-3组成的二元复合驱油体系及由质量浓度为1500mg/L的ZL-Ⅱ、质量分数为0.3%的QY-3和1.0%的Na2CO3组成的三元复合驱油体系,这2个体系均能与双河模拟油形成超低界面张力且粘度适中。利用均质与非均质人造岩心及微观非均质仿真模型,对所选复合驱油体系进行物理模拟驱油实验;并在模拟油藏具有代表性的3倍渗透率级差条件下,优选了三元复合驱油体系注入方式。实验结果表明,在均质条件下,三元复合驱油体系提高采收率程度明显高于二元复合驱油体系;在非均质条件下,随着非均质性的增强,三元复合驱油体系与二元复合驱油体系提高采收率的差距逐渐缩小,但前者始终高于后者;对于同一驱油体系,随着非均质性的增强,驱油效率先增大后减小,渗透率级差为3倍时的采收率最高。综合分析可知,三元复合驱油体系好于二元复合驱油体系,在其注入前后分别注入0.05倍孔隙体积交联聚合物保护段塞的注入方式,三元复合驱油体系提高采收率比不加保护段塞时提高了4%。     

Study the Influence of Some Polymeric Additives as Viscosity Index Improvers,Pour Point Depressants and Dispersants for Lube Oil

Abstract

In the present work, some polymeric additives were prepared as pour point depressants, viscosity index improvers and dispersant additives for lube oil, these additives prepared by copolymerization of maleic anhydride with different esters of acrylic acids and then amination. The molecular weights of the prepared copolymers were determined by gel permeation chromatograph (GPC). The efficiency of the prepared compounds as pour point depressants and viscosity index improvers was investigated. It was found that the efficiency of the prepared compounds as pour point depressants increases with decreasing the concentration of the prepared polymers, increasing the chain length of alkyl groups and increases with decreasing the molecular weight. The efficiency of the prepared compounds as viscosity index improvers increases by increasing the concentration of these additives and by increasing the molecular weight of polymer. It was found that the amination of polymer enhance the efficiency of the prepared additives as pour point, viscosity index, and dispersant for sludge.     

驱替体系的主要性质对驱油效率的影响

为了深入研究粘弹性、粘度和界面张力等性质对驱油效率的影响,采用系列驱替体系进行了大量的物理模拟实验。与前人研究方法不同,实验中将表面活性剂和碱的质量分数分别固定为0.3%和1.2%,通过调整烷基苯磺酸盐表面活性剂的组成配方,使三元复合体系具有不同的界面张力数量级,避免了化学剂质量分数变化引起的实验偏差。研究结果表明,在相同粘度下,三元复合体系的弹性小于聚合物溶液;与水驱相比,单独聚合物驱和表面活性剂—碱二元驱可分别提高采收率14.37%和7.05%;同时改变粘度和界面张力可提高采收率30.41%,证明两者的协同作用效果优于改变单因素时驱油效率的简单加和;粘度越高,降低界面张力对提高驱油效率的影响越大。因此,合理匹配粘度与界面张力之间的关系是提高驱油效率的有效途径。     

新疆油田复合驱过程中的乳状液类型转变

为分析新疆油田部分采油井二元复合驱油中出现高黏度(3000 m Pa·s)油包水型乳状液现象的原因,室内模拟化学驱中表面活性剂/聚合物二元复合体系与原油的乳化过程,研究了矿化度、油水比、表面活性剂浓度和地层水稀释对乳状液类型的影响,建立了在岩心驱油过程中乳状液的转变模型。研究结果表明,当矿化度较低(100 mg/L Na Cl)时,乳状液主要为水包油型;随着矿化度的增大,水包油型乳状液的稳定性变差,当矿化度达到10 g/L时,乳状液开始向油包水型转变。油水比为1∶9和3∶7时,乳状液主要为水包油型;当油水比为5∶5、表面活性剂加量为500 mg/L时,乳状液为油包水型。随着地层水稀释比例的增加,乳状液由水包油型向油包水型转变。室内岩心驱油实验结果表明,随着二元体系的注入与推进,矿化度升高,表面活性剂浓度降低,油水比变大,导致乳状液产生了由水包油型向油包水型的转化。     

驱油聚合物水溶液黏度稳定剂的研究

针对聚合物溶液在聚合物驱环境中黏度损失严重进而影响了驱油效果的问题。对聚合物水溶液黏度的影响因素和特点进行了分析,研制并筛选出了黏度稳定剂JW-1,并对其增黏稳黏效果进行了室内评价。试验结果表明,与空白的HPAM溶液相比,JW-1加量在800~1200 mg/L时,HPAM体系黏度增加了3倍左右,当其加量为1000 mg/L时,HPAM体系60 d后黏度基本保持稳定,黏损率约为10.1%,而空白的HPAM体系黏损率高达50%以上;JW-1与清污混配的HPAM溶液配伍性好,不产生悬浮物或絮状物。可望在聚合物驱油和深度调剖方面得到应用。     

One Factor Influencing the Oil-displacement Ability of Polymer Flooding: Apparent Viscosity or Effective Viscosity in Porous Media?

Abstract

Polymer flooding has been an important process to enhance oil recovery (EOR) worldwide. In practice, partially hydrolyzed polyacrylamides (HPAMs) have many defects including shear degradation and sensitivity to salt. For these reasons, hydrophobically associating polyacrylamides (HAPAMs) have been developed for harsh oil reservoirs. In this work, the properties of two classes of polymers (HPAMs and HAPAMs), including apparent viscosities, effective viscosities in porous media, and oil-displacement efficiencies, are studied. As expected, HAPAM exhibits apparent viscosity enhancement properties due to intermolecular hydrophobic association while HPAM cannot. However, the effective viscosity of HAPAM is always lower than HPAM possibly because of adsorption loss and the reduction in strength of the hydrophobic association through porous media. The tertiary oil recovery increases with the increment of the effective viscosity of polymer. Oil-displacement efficiency of HAPAM is also lower than HPAM at the same concentration of 2,000 mg/L.     

Microemulsions in Enhanced Oil Recovery: A Review

Abstract

Microemulsions have recently made advances in enhanced oil recovery processes in which chemicals, especially surfactants, are used to recover the oil from natural oil reservoirs. This technique relies on the knowledge of interfacial properties among oil, water, and solid rock reservoirs in the occasional presence of natural gas under extreme conditions. Surfactant-based chemical systems have been reported in many academic studies and their technological implementation is a potential candidate in enhanced oil recovery (EOR) activities. For instance, it was determined that a mobilized buffer (polymer) with viscosity either equal to or greater than the mobilized oil enhanced the recovery efficiency considerably. However, EOR based on chemicals like alkaline–surfactant–polymer (ASP) is a complex technology requiring a high level of expertise for its industrial implementation. The surfactant–polymer interaction is a rapidly growing research area for efficient oil recovery by improving slug integrity, adsorption, and mobility control. This review article evaluates the injecting fluid system to highlight some recent advances in the use of chemicals in EOR, especially with microemulsions. It further reveals the current status and future outlook for EOR technology in oil fields and describes the opportunities for strategic utilities and load growth in petroleum industry.     

Synthesis and Evaluation of Some Polymeric Compounds as Pour Point Depressants and Viscosity Index Improvers for Lube Oil

Abstract

In the present study, some polymeric additives were prepared and used as pour point depressants and as viscosity index improvers for lube oil via copolymerization of maleic anhydride and vinyl acetate with different esters of acrylic acid. The molecular weights of the prepared copolymers were determined by GPC. The efficiency of the prepared compounds as pour point depressant and viscosity index improvers was investigated. It was found that the efficiency of the prepared compounds as pour point depressant increases with decreasing the concentration of the prepared polymers, increasing the chain length of alkyl groups, and increases with decreasing the molecular weight. The efficiency of the prepared compounds as viscosity index improvers increases by increasing the concentration of these additives and by increasing the molecular weight of the polymer.     

不同浓度组分可控烷基苯磺酸盐弱碱三元体系乳化规律

三元驱油体系在地层运移过程中化学药剂浓度发生变化,使得三元驱油体系与原油乳化特性也发生改变。针对组分可控烷基苯磺酸盐弱碱三元体系在地层运移过程中与原油的乳化特性开展实验研究。结果表明：使用均化仪对体系及原油进行乳化后,组分可控烷基苯磺酸盐弱碱三元体系中聚合物浓度越低,乳化后体系黏度增幅倍数越大;乳化后三元体系界面张力变化不大,Zeta电位小幅下降,乳状液类型以油/水型为主;三元体系乳化析水率、乳化特性变化明显,其原因是表面活性剂的分子结构影响较大,与界面张力及Zeta电位关系不大。正交实验方法分析了组分可控烷基苯磺酸盐表面活性剂、碳酸钠及中等相对分子质量聚合物这3种不同类型化学药剂对组分可控烷基苯磺酸盐弱碱三元体系乳化特性的影响规律。方差分析结果表明：影响乳状液黏度因素由大到小的顺序为：聚合物、弱碱、表面活性剂,当聚合物质量浓度为600 mg/L时,乳状液黏度增幅倍数最大;影响乳化析水率的因素由大到小的顺序为：弱碱、表面活性剂、聚合物,当Na₂CO₃质量分数为0.3%、表面活性剂质量分数为0.3%、聚合物质量浓度为1000 mg/L时,乳化体系在24 h时的乳化析水率最低,乳化特性最明显。     

Water-in-Crude Oil Emulsion Stability Investigation

Abstract

The water-in-crude oil emulsion has great importance in the oil industry. The stability of water-in-crude oil emulsion is investigated over a wide range of parameters. These parameters are water concentration (10–50%), surfactant concentration (0.1–1%), mixing speed (500–2, 000 rpm), salt concentration (0–5%), polymer concentration (0–1, 000 ppm), and temperature (13–40^○C). The physical properties of water-in-crude oil emulsion in terms of density, viscosity, and interfacial tension are measured by Pycnometer, Ostwald viscometer, and spinning drop tensiometer, respectively. The stability of water-in-crude oil emulsion is studied for each case in details. This investigation shows that the presence of the emulsifying agent is necessary for stable emulsion, and stability gradually decreases with water concentration. The presence of 5% NaCl or 1, 000 ppm of Alcoflood polymer provides 100% stable emulsion. Emulsion stability reduces with temperature. Impeller type has a strong effect on the emulsion stability. S-curved blade impeller provides 100% stable emulsion for more than 2 days.     

调剖用凝胶的吸水溶胀特性评价及改进

针对常规聚丙烯酰胺凝胶在化学剖面调整中逐渐暴露出的技术局限性,开展了50~90℃温度范围内的铬交联体系和酚醛树脂交联体系的水浸泡及黏度损失研究,并遵循"达西定律"基本理论,从增加交联密度、降低凝胶溶胀度的角度入手,引入新的可溶性高分子材料来改善常规凝胶交联强度。结果表明,凝胶在水中充分浸泡时,黏度会随着反应时间的延长而降低,凝胶在水中存在溶胀作用及黏度损失。添加剂PVA易与聚丙烯酰胺分子间形成网络内氢键或缠绕,起到物理交联点的作用,使凝胶黏度提高30%,考察180 d后黏度损失小于10%。该研究可为解决层间矛盾、启动低渗透层段的生产潜力提供技术支持。     

高浓度三元复合体系增油效果及其作用机理研究

本文分析了高浓度三元复合驱增油效果的影响因素和经济效益。结果表明,在驱油剂费用相同时,0.12%高分聚合物驱、0.3%非离子表面活性剂/0.25%超高分聚合物二元复合驱、1.2%碱/0.3%磺酸盐/0.25%超高分聚合物三元复合驱的采收率增幅分别为19.6%、15.9%、13.7%。在高浓度三元复合体系黏度相同的条件下,体系界面张力由8.10×10^-1降至5.73×10^-3 mN/m,采收率增幅由23.4%增至27.7%。当三元复合驱黏度由36.8增至134.4 mPa·s时,采收率增幅由18.5%增至32.9%;当段塞尺寸由0.095增至0.475 PV时,采收率增幅由15.6%增至30.7%,但采收率增幅差值逐渐减小。在药剂费用相同的条件下,“聚合物前置段塞+三元主段塞+三元副段塞+聚合物保护段塞”组合的采收率增幅较大（33.8%）。从技术和经济效益方面考虑,推荐三元复合体系聚合物浓度范围为0.2%～0.25%,段塞尺寸为0.380～0.475 PV。对于非均质比较严重的油藏,与驱油剂洗油作用相比,其扩大波及体积作用对采收率的贡献较大。     

射孔不渗流段对疏水缔合聚合物溶液黏度的影响

本文针对聚合物在注入过程中存在黏度损失的问题,根据现场的注聚井的完井参数,设计射孔不渗流段模拟装置。通过对不渗流段长度、注入速度、注入浓度及剪切后静置时间对疏水缔合聚合物溶液黏度的影响。实验结果表明:增加射孔不渗流段和注入速度,剪切后聚合物溶液的黏度急剧下降,当增加到一定值时,黏度损失幅度减小;增加聚合物溶液的浓度,剪切后聚合物溶液黏度损失幅度就越小;剪切后的聚合物溶液静置一段时间有助于黏度的恢复。通过以上实验对聚合物溶液的注入参数优选提供一定的数据支撑。     

Binary phase diagram series: 1,3,3-trinitroazetidine (TNAZ)/2,4,6-trinitrotoluene (TNT)

Abstract

The binary phase diagram for the 1,3,3-trinitroazetidine (TNAZ)/2,4,6-trinitrotoluene (TNT) system has been predicted computationally and determined experimentally. The calculated eutectic temperature/composition is 60.6 °C/35.3 mol percent TNAZ. It has been demonstrated that mixtures of TNAZ and TNT exhibit the thermal characteristics associated with a binary eutectic system affected by component interaction and by apparent polymorphism that is attributed to the TNAZ component. It is believed the former causes both the liquidus temperatures and heats of fusion from the initial melting operations to be significantly lower than calculated.     

稠油油藏污水活性碱/聚二元复合驱室内试验研究

羊三木油田碱/ 聚驱先导试验存在现场污水配制碱/ 聚二元复合驱体系时出现结垢堵塞地面管线、聚合物严重降解等问题，为此开展了污水配制新型碱/ 聚合物二元复合驱体系研究。采用抗钙镁结垢能力强、降低界面张力幅度大的活性碱与污水聚合物匹配，分析在污水配制条件下，不同碱型与聚合物匹配的驱油能力，以及在原油黏度高达530 mPa·s 时能否继续开展二元复合驱的问题。研究结果表明 :原油黏度为530 mPa·s，污水配制活性碱/ 聚合物二元复合体系溶液黏度为45 mPa·s 时，油水界面张力达到10－3 数量级，活性碱/ 聚合物二元复合驱比纯水驱提高采收率17% 以上；在原油黏度确定及油水界面张力已降至超低值时，超过碱/ 聚二元体系溶液浓度技术临界点后，即使继续增加溶液黏度，采收率也不会大幅度增加。该研究为普通稠油油藏注水开发后期化学驱提高采收率提供了新型有效的技术手段。     

高30油藏二元复合体系化学剂的静态吸附

在高30高温油藏条件下,测定了固液界面吸附量和二元复合体系等温吸附曲线。结果表明,缔合聚合物HNT201-3和表面活性剂CDS-1在二元复合体系中的吸附规律和特征,都符合朗格缪尔等温吸附曲线。得出了聚合物的吸附平衡浓度为1000mg/L,表面活性剂吸附平衡浓度为0.05%,对驱油体系中各化学剂浓度的确定起到了指导作用。