减阻剂在页岩气压裂中的研究及应用

滑溜水压裂液具有低黏度以及降摩阻等优点,可深入地层,构造更加复杂的缝网结构,是非常规油气藏降本增效的重要技术手段.减阻剂作为滑溜水中的主要组成部分,主要用于降低压裂液与管壁间的摩擦阻力,提高作业效率.介绍了生物基多糖、表面活性剂以及聚丙烯酰胺这3种类型减阻剂的主要减阻机理及其各自减阻效率,详述了其各自的研究进展与应用现状.结合储层特征与实际需求,量体设计即配即注、高携砂、低摩阻、多效合一、环境友好的减阻剂是现阶段压裂用滑溜水的主要研究攻关方向.     

减阻剂乳液的合成与性能评价

采用水分散聚合法制备了一种应用于滑溜水中的水溶性减阻剂乳液,对减阻剂溶液的粘弹性、耐温耐剪切性和降阻率进行了测试.结果表明,该减阻剂溶液具有明显的粘弹性特征,耐温耐剪切性能良好,0.2％的减阻剂水溶液的最大降阻率超过70％,表现出了良好的降阻特性,能够作为滑溜水用减阻剂使用.     

一种新型滑溜水压裂液降阻剂合成与应用研究

减阻剂是滑溜水压裂液的核心添加剂,采用反相乳液聚合法合成了一种新型降阻剂,并以其为主剂,配制了一种滑溜水压裂液体系。考察了降阻剂的各项性能和滑溜水压裂液体系对岩心渗透伤害和裂缝导流能力伤害性能。试验结果表明:降阻剂具有较好降阻性能和携砂性能;该降阻剂配制的滑溜水压裂液对岩心渗透伤害率低、对支撑剂导流能力的伤害率低,对支撑剂导流能力的伤害恢复率达到95.8%;该降阻剂配制的滑溜水压裂液具有低摩阻和高弹性的特点,可以实施大液量、大排量、大砂量的施工。     

滑溜水压裂液中减阻剂的制备及特性研究

采用反相微乳液法制备了一种用于滑溜水压裂液中的水溶性减阻剂,对减阻剂的粒径大小分布、重均分子量、降阻率和悬砂能力进行了测试。结果表明,减阻剂粒径小,分布窄,分子量高[Mw=(2.08±0.65)×107g/mol],具备高分子减阻的特性;向清水中加入0.05%的减阻率,减阻率可达55%,并且具有一定的携砂能力。因此,该减阻剂的应用能很好的降低压裂施工摩阻、减小泵功、适当提高砂比,有助于非常规低渗储层的开采。     

滑溜水压裂液技术的发展现状

滑溜水压裂技术是当今世界油气田开发作业中应用最多的压裂技术之一,其技术关键在于滑溜水压裂液体系配方的研制。本文在介绍其体系配方的同时,对滑溜水压裂技术的优缺点及适应性进行了阐述。     

FLICK减阻剂低温低伤害滑溜水研究与现场应用

EYY1HF井是位于黄陵背斜的一口评价井,试气目的层为寒武系水井沱组一段,地层压力系数1.0～1.1,目的层温度55℃,属于常压低温页岩气井。在压裂改造过程中要求滑溜水中高分子聚合物在储层温度下可降解,压后具有较低的表面张力及较少的残渣,利于压后返排,减少储层伤害;此外,要求滑溜水黏度可调,可实现"变黏"压裂,提高裂缝复杂性。针对上述要求,开展了减阻剂、助排剂、黏土稳定剂及聚合物降解剂等添加剂研究及性能评价,通过配伍性实验及综合性能评价形成了FLICK减阻剂低温低伤害滑溜水体系。该体系减阻率70%,表面张力28 mN/m,毛细管吸收时间(CST)比值1.5,膨胀体积3 mL,在20℃条件下降解液黏度2 mPa·s,降解后分子量10 000,应用结果表明,该体系可以满足常压低温页岩气藏体积压裂的需求。     

适用于页岩气开发的高效滑溜水压裂液体系研究

为满足页岩气储层体积压裂对大排量、大液量的要求,需采用滑溜水压裂液体系进行压裂施工。通过大量室内试验,优选出了性能优良的压裂液添加剂,包括减阻剂CY-1、防膨剂CRJ-2和助排剂CPJ-1,并通过浓度优选以及性能评价等试验,建立了一套适合页岩气储层开发的高效滑溜水压裂液体系,具体配方(w)为:0.1%减阻剂CY-1+1.5%防膨剂CRJ-2+0.5%助排剂CPJ-1。对优选的高效滑溜水压裂液体系进行了性能评价,结果表明:该压裂液体系属于假塑性流体,具有良好的流变性能;其降摩阻性能明显优于常规胍胶压裂液体系,具有低摩阻特点;并且压裂液体系对储层段天然岩心的渗透率伤害率仅为5%左右,具有低伤害的特性,能够满足目标区块页岩气储层压裂施工对压裂液性能的要求。     

高分子量乳液型减阻剂的合成及评价

采用反相乳液聚合方法制备了一种用于滑溜水压裂液的高分子量乳液型减阻剂。考察了复合乳化剂对乳液减阻剂稳定性的影响,研究了乳化剂含量、聚合温度和引发剂浓度对减阻剂分子量的影响,分析了减阻剂的分子结构、乳液粒径大小分布和减阻效率。实验结果表明:m(Span80)∶m(Tween80)∶m(OP-10)=20∶2∶1时乳液最为稳定;在18℃、乳化剂在油相中质量分数为15%、引发剂质量为单体质量的0.015%时,得到分子量达1.8×107g/mol的稳定乳液型减阻剂。在清水中加入0.05%的减阻剂,减阻率高达62.8%。     

减阻水及其添加剂的研究进展及展望

概述了美国页岩气减阻水技术发展历程，对减阻水重要的两种添加剂——减阻剂和表面活性剂、以及其他添加剂的国外研究新进展进行了综述，分析了各个添加剂的内涵及作用，总结了国内减阻水压裂液的研究进展和不足，提出了减阻水对我国页岩气压裂改造的应用前景和几点建议。     

DR-1减阻剂相对减阻率影响因素分析

减阻剂对页岩气、煤层气和致密气等非常规油气资源的开发具有重要的意义,其在滑溜水压裂液体系中主要通过降低摩阻起到降低能耗、增加排量的作用。在现场使用中,配液用水的无机金属离子含量、减阻剂浓度和温度等因素会影响减阻剂的性能。本文考察了无机金属离子、减阻剂浓度和温度等因素对减阻剂减阻效果的影响。结果表明:温度升高导致DR-1粘度降低,进而减阻率也逐渐降低,温度高于60℃时,DR-1减阻率损失率达20%以上;无机金属离子尤其是Ca2+、Mg2+对减阻剂减阻性能影响较大,当水中Ca2+、Mg2+为800mg/L时,DR-1减阻率损失率达20%以上。     

Preparation and evaluation of acryloyl morpholine modified emulsion fracturing fluid thickener with high temperature resistance and salt resistance

To prepare the thickener of fracturing fluid with temperature resistance, salt resistance and quick dissolution, an emulsion thickener (ASC) was synthesized by acrylamide, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, and acryloyl morpholine. The dissolution, salt resistance and drag reduction of ASC, and the viscoelasticity, temperature resistance and shear resistance and gel breaking properties of fracturing fluid formed by ASC and zirconium crosslinker were investigated. The results showed that the sticky time of ASC was less than 60 s and the drag reduction rate was 72.5% in 100,000 mg/L brine, showing that ASC had thickening ability in high salinity brine and satisfied the requirements of continuous fluid preparation on the fracturing process. The viscosity of ASC fracturing fluid was 98 mPa s after shearing at 200°C and 170 s⁻¹ for 150 min when the salinity was 100,000 mg/L. When the ammonium persulfate concentration was 400 mg/L, the viscosity of the broken fluid was 4.0 mPa s. The temperature resistance, salt resistance and shear resistance of ASC emulsion fracturing fluid could be significantly improved by the introduction of acryloyl morpholine, ASC fracturing fluid had the characteristics of high elasticity and low viscosity, which could meet the application requirements under ultra-high temperature reservoirs.     

聚丙烯酰胺压裂液减阻剂的合成及性能

目前,非常规油气藏的开采备受重视,常规水基冻胶压裂液因其流变性较差及摩阻较高而无法满足降压增注的施工工艺,达到体积压裂的目的。为了解决伤害性较大及摩阻较高等问题,本文推出了一种能够同时满足降低摩阻、提高流变性的压裂液减阻剂。采用反相乳液聚合方式合成出了此种聚丙烯酰胺压裂液减阻剂,通过优化合成工艺,利用丙烯酰胺、3-烯丙基-2-羟基-1-丙烷磺酸钠及丙烯酸十八酯合成出了一种性能稳定的白色乳液压裂液减阻剂,并利用红外光谱仪、投射电子显微镜及激光粒度仪对聚丙烯酰胺乳液的结构及乳液粒径进行表征,结果表明,聚丙烯酰胺压裂液减阻剂中含有磺酸基和十八酯基团,乳液粒径为80nm,粒径较小。随后通过对乳液的减阻率及流变性测试,研究结果表明,在室温下,流速为10m/s、浓度为1g/L时,压裂液减阻剂的减阻率为78%,减阻性能较好,另外,压裂液减阻剂具有较好的溶解性、耐剪切性和黏弹性,与常规黏土稳定剂和助排剂有着较好的配伍性。能够满足非常规油气藏体积压裂施工要求。     

高分子减阻剂减阻性能的影响因素研究

对减阻剂减阻性能的影响因素进行了系统讨论,阐述了聚合物相对分子质量及相对分子质量分布、聚合物空间结构、聚合物抗剪切降解、聚合物后处理等因素对减阻性能的影响,并提出我国应加大对减阻剂的生产及利用研究。     

耐高温交联酸压裂液的研制及其性能评价

针对黏弹性表面活性剂(VES)转向酸使用成本高，耐温性差以及现有胶凝酸破胶不完全的问题，本研究首先通过水溶液聚合法合成稠化剂和有机锆交联剂，然后在质量分数为20%的盐酸水溶液(下同)中将稠化剂通过有机锆交联剂进行交联，得到耐高温交联酸基液，再根据压裂液性能要求添加高温缓蚀剂、助排剂、铁离子稳定剂和黏土稳定剂，研发了一种耐180 ℃高温的交联酸压裂液。采用高温高压流变仪、压裂液摩阻测试仪和表界面张力测定仪等对交联酸压裂液进行性能评价。结果表明，所制备的交联酸压裂液在180 ℃、170 s^-1条件下剪切120 min后，黏度仍可维持为73 mPa·s，加入0.15%过硫酸铵破胶后，黏度降为3.2 mPa·s，高温流变性和破胶性能良好。     

超临界CO2压裂液增黏剂的长管实验评价及增黏机制探讨

针对超临界CO₂压裂中CO₂黏度低、携砂困难等问题,开展6种超临界CO₂压裂液增黏剂的性能研究。分析增黏剂聚乙酸乙烯酯、聚苯乙烯、氟化丙烯酸酯、聚甲基倍半硅氧烷、聚甲基倍半硅氧烷-乙酸乙烯酯以及氟化丙烯酸酯-苯乙烯的分子结构,测试其增黏效果及热稳定性,评价温度、压力、增黏剂注入量对超临界CO₂压裂液黏度的影响,测试不同管径中压裂液的阻力系数,并探讨超临界CO₂增黏的机制。实验结果表明,在温度为50℃、压力为12MPa、注入增黏剂质量分数为3%时,氟化丙烯酸酯-苯乙烯对超临界CO₂的增黏效果最好,增黏倍数为316.7倍,黏度值为15.202mPa·s;改善增黏剂在CO₂中的溶解性可以有效提高超临界CO₂压裂液的黏度;具备两亲特性、具有无定形、无规则结构特征以及分子上既存在路易斯酸又有路易斯碱的共聚物能有效提高其在CO₂中的溶解性,并形成大分子相互缠绕的空间网络结构,达到增黏的效果。该研究对超临界CO₂增黏剂的研制以及超临界CO₂压裂施工具有重要的现实意义。     

Synthesis and performance evaluation of a new drag reducer based on acrylamide/12-allyloxydodecyl acid sodium

Hydraulic fracturing with slickwater is a field-proven stimulation technology used in tight reservoirs. Because of the high pumping rate associated with slickwater fracturing, drag reduction (DR) is critical in minimizing pressure drop and the success of oilfield operations. In this paper, a new type of drag reducer (SPR) was synthesized with acrylamide and 12-allyloxydodecyl acid sodium, and its drag reduction performance was evaluated. The results showed that the new drag reducer features low molecular weight, fast-dissolving rate and low interfacial tension. The algorithm of estimating the drag reduction rate of non-Newtonian fluid SPR was proposed and validated. Empirical or semianalytical models for estimating the friction ratio (σ) or friction factor (λ or f) were used to simulate the turbulence behavior of the SPR drag reducer under different Reynolds numbers (Re). The modified Virk's correlation could accurately model the turbulent behavior of the SPR drag reducer. A unified calculation formula was established in this study for different pipe diameters.     

Going against the flow—A review of non-additive means of drag reduction

The conventional mainstream method of polymer additives for reducing drag in pipes is disadvantageous from certain environmental perspectives. This paper aims to go against the flow by challenging the widespread preference for using polymeric and surfactant-based drag reducers and discusses the performance of five alternative methods that do not involve polymer additives: riblets, dimples, oscillating walls, compliant surfaces, and microbubbles. The hypothetical mechanisms involved, success of each approach, relevant stages of development, important findings, and possible avenue for future research are discussed. The results obtained in this paper have exposed the potentials of new drag reduction technologies.     

Roles of drag reducing polymers in single- and multi-phase flows

It has become a well-known fact that finding sustainable solutions to the unavoidable high pressure losses accompanying pipeline flows to increase the pumping capacity without necessarily adding more pump stations is inevitable. Polymers, as one of the drag reducing agents which have been found to offer such an economic relieve, is the most widely investigated and most often employed in industries because they can produce drag reduction up to 80% when they are added in minute concentrations. In addition, polymer additives modify the flow configurations of multiphase flows to such an extent that stratification of individual phases is enhanced thereby making the separation of the phases at the fluid destination much easier. The achievements so far made and the challenges facing the use of polymers as drag reducers in turbulent single and multiphase flows are comprehensively reviewed. This review discusses the experimental studies of the effects of polymer additives in turbulent flows, the analytical studies, and the proposed models as well as the suggested mechanisms that explain the drag reduction. Likewise, specific areas of interest in the review include phenomena of drag reduction by polymers, factors influencing the effectiveness of the drag reducing polymers, methods of injecting the polymers into the base fluids, degradation of the polymers and industrial applications of polymers as drag reducing agents. The current and future research interests are also addressed. Although finding reveals that there are quite a lot of research in this area, most of the experimental and theoretical works are devoted to single phase flows while the remaining ones are mostly directed towards gas–liquid flows except in very recent time when investigation into the use of polymers in liquid–liquid flows is being focused. Despite this voluminous works on drag reducing polymers, there are no universally accepted models and hence the mechanisms of drag reductions by polymers.     

中高温清洁压裂液研究及应用进展

介绍了清洁压裂液的特点,叙述了目前国内外清洁压裂液适用温度在80℃以上中高温清洁压裂液的研究进展和在油井中的应用、煤层气井现场应用情况。最后对目前开展中高温清洁压裂液的研究提出了一些建议。认为今后应研制出适合天然气破胶的破胶剂或者破胶促进剂．开发出适用于不同地层条件的完整的清洁压裂液体系。应降低VES合成成本、降低用量,加强复合压裂液的研究,进一步拓宽清洁压裂液技术的应用范围。     

一种适合松南深层储层的缔合型压裂液

针对松南地区深层储层埋藏深、岩性致密、微裂缝发育、渗透率低、地层温度高、破裂压力高等特点,采用新型缔合型稠化剂研制了一种新型低伤害压裂液.试验表明该压裂液抗温性能良好,残渣含量小于10mg/L,储层岩芯伤害率小于15％,支撑裂缝导流能力保留率大于10％,降阻率大于70％.现场应用取得了良好效果,为松南地区深层储层的开发提供了一条新的途径.