State of the art of synthetic threshold scale inhibitors for mineral scaling in the petroleum industry: a review

Inorganic scale deposits are a major water-related problem encountered in producing oil and gas wells. The harshness of scale deposits is dependent on the field operating conditions. Scale deposits can vary from mild scaling tendencies to extreme. In general, the scale deposit will cause a reduction in formation pores, declining productivity and eventually blockage of the wellbore and hence unexpected downtime if it is allowed to persevere. To overcome this, the productivity of an oil and gas well is ensured by handling scale deposits via removal or prevention methods. Scale prevention is the best and cost-e ective method for handling scale deposits that ensures production continuity. Inhibition through 'threshold' scale inhibitor treatment is the most common method that is proven to prevent or reduce likely deposits. This paper examines the art of synthetic scale inhibitors, in particular, threshold scale inhibitors in oil and gas production. It discusses the chemistry of those inhibitors, inhibition mechanisms, treatment methods and key properties for their applications. It also highlights the chemistry of the synthetic routes often used to produce them in the laboratory and/or industry. Finally, it highlights the environmental concerns for the applicability of threshold scale inhibitors.

Corrosion Inhibition of a Green Scale Inhibitor Polyepoxysuccinic Acid

The corrosion inhibition of a green scale inhibitor, polyepoxysuccinic acid (PESA) was studied based on dynamic tests. It is found that when PESA is used alone, it had good corrosion inhibition. So, PESA should be included in the category of corrosion inhibitors. It is not only a kind of green scale inhibitor, but also a green corrosion inhibitor. The synergistic effect between PESA and Zn2+ or sodium gluconate is poor. However, the synergistic effect among PESA, Zn2+ and sodium gluconate is excellent, and the corrosion inhibition efficiency for carbon steel is higher than 99%. Further study of corrosion inhibition mechanism reveals that corrosion inhibition of PESA is not affected by carboxyl group, but by the oxygen atom inserted. The existence of oxygen atom in PESA molecular structure makes it easy to form stable chelate with pentacyclic structure.

The Preparation and Performance Study of a Phosphate-Free Corrosion/Scale Inhibitor

By using acrylic acid copolymer, sodium citrate, hydrolyzed polymaleic anhydride (HPMA), corrosion inhibitor D and Zn2+ synergist as raw materials, a multi-component phosphate-free corrosion and scale inhibitor was developed. The performance of the composite phosphate-free corrosion and scale inhibitor was evaluated using the rotary hanging sheet corrosion test, the static scale inhibition test and the corrosion electrochemical test. And the surface morphology of the carbon steel was observed by scanning electronic microscope (SEM). Orthogonal experiment results indicated that the optimal mass ratios of amino acid: Zn2+ synergist: HPMA: corrosion inhibitor D: acrylic acid copolymer was 0.5:10:12:1:8. It was also observed that phosphate-free corrosion and scale inhibitor based on an anodic reaction through the electrochemical corrosion experiment, its annual corrosion rate and scale inhibition rate reached 0.0176 mm·a–1 and 98.3%, respectively, showing excellent corrosion and scale inhibition performance.

Experimental Study on a New Corrosion and Scale Inhibitor

The mixture consisted of benzotriazole (BTA), chitosan (CTS), polyacrylic acid and zinc salt has been investigated as a corrosion and scale inhibitor of A3 carbon steel in cooling water. The scale and corrosion inhibition efficiency was evaluated by static anti-scaling teat together with rotary coupon test. Compared with the phosphorus corrosion and scale inhibitor, the corrosion inhibition rate and scale inhibition rate of it increased respectively by 2.51% and 1.16%. As the corrosion and scale inhibitor is phosphate-free, it won’t cause eutrophication, considering the product performance and environmental influence, the phosphate-free corrosion and scale inhibitor is superior to the traditional one.

Laboratory investigation of a new scale inhibitor for preventing calcium carbonate precipitation in oil reservoirs and production equipment

The formation of mineral scale is a complex problem during the oilfield operations. Scale inhibitors are widely used to prevent salt precipitation within reservoirs, in downhole equipment, and in production facilities. The scale inhibitors not only must have high effectiveness to prevent scale formation, but also have good adsorption- desorption characteristics, which determine the operation duration of the scale inhibitors. This work is focused on the development of a new scale inhibitor for preventing cal- cium carbonate formation in three different synthetic for- mation waters. Scale inhibition efficiency, optical density of the solution, induction time of calcium carbonate for- mation, corrosion activity, and adsorption-desorption ability were investigated for the developed scale inhibitor. The optimum concentration of hydrochloric acid in the inhibitor was determined by surface tension measurement on the boundary layer between oil and the aqueous scale inhibitor solution. The results show that the optimum mass percentage of 5 % hydrochloric acid solution in the inhi- bitor was in the range of 8 % to 10 %. The new scale inhibitor had high efficiency at a concentration of 30 mg/L. The results indicate that the induction period for calcium carbonate nucleation in the presence of the new inhibitor was about 3.5 times longer than the value in the absence of the inhibitors. During the desorption process at reservoir conditions, the number of pore volumes injected into the carbonate core for the developed inhibitor was significantly greater than the volume of a tested industrial inhibitor, showing better adsorption/desorption capacity.

Study on a Novel Composite Eco-Friendly Corrosion and Scale Inhibitor for Steel Surface in Simulated Cooling Water

The use of organophosphorus inhibitor is diminishing because of its toxic effects on aquatic and other life. In this study, a composite eco-friendly phosphate-free corrosion and scale inhibitor HS has been developed using hydrolyzed polymaleic anhydride (HPMA), sodium gluconate, Zn2+ synergist and sulfamic acid. And the formula ratio of each component is 9:5:4:2. The performance of the corrosion and scale inhibitor was evaluated by weight loss experiment and the static scale inhibition test, respectively. The results indicated that HS had positive corrosion and scale inhibition effect at a dosage of 40 mg.L–1 or higher. Potentiodynamic polarization curves indicated that HS inhibits the corrosion of steel based on controlling the anodic reaction. And the surface morphology of the carbon steel was studied by scan-ning electronic microscope (SEM). The inhibition effects were due to the formation of protective films.

The state of the art in scale inhibitor squeeze treatment

The mechanistic understanding of the reactions that govern the inhibitor retention and release,modeling,and the state-ofthe-art innovation in squeeze treatment are reviewed.The retention and release are governed by(1)the amount of calcite that can dissolve prior to inhibitor-induced surface poisoning;(2)calcite surface poisoning after^20 molecular layers of surface coverage by the adsorbed inhibitors to retard further calcite dissolution;(3)less base,CO3^2-,is released into the aqueous solution;(4)formation of the more acidic inhibitor precipitates;(5)phase transformation and maturation of the more acidic inhibitor precipitates;and(6)dissolution of the less soluble crystalline inhibitor precipitates.The trend to advance squeeze technologies is through(1)enhancing scale inhibitor retention,(2)optimizing the delivery of scale inhibitors to the target zone,and(3)improving monitoring methods.Lastly,a prototype yardstick for measuring the squeeze performance is used to compare the squeeze life of 17 actual squeeze treatments.Even though the various squeeze treatments appear to be different.all published squeeze durations can be rated based on the normalized squeeze life per unit mass of inhibitors.

The Performance of ZX Type Scale Inhibitors in Evaporation Process of Salt Electrolyte

Rapid fouling tests were used to investigate the scale-preventing property of ZX type scale inhibitors in evaporation of salt electrolyte. ZX type scale inhibitors were tested at high temperature under the boiling conditions. The results indicate that ZX type scale inhibitors have remarkable scale preventing performance during evaporation of salt electrolyte even at the temperature up to 150℃. Among them, ZX Ⅲ type scale inhibitor is the best with the rate of scale-preventing reaching to 88.9%. In addition, the scale preventing mechanism of ZX type scale inhibitors was analyzed and its application prospect in the field of continuous commercial fouling preventing discussed.

电化学水处理技术降低循环水硬度的实验研究

使用电化学法处理某焦化企业实际循环水的实验,探究了循环水的硬度和碱度去除率随处理时间的变化情况。分析了电流密度、水力停留时间、极板间距等实验操作参数以及商用阻垢剂对电解效果和能耗的影响。结果表明:硬度和碱度去除率随处理时间呈现先上升后平稳的趋势,且碱度去除率总是高于硬度去除率;电流密度为70 A/m^(2)、水力停留时间为6 min、极板间距为3 cm时电解效果最佳,硬度和碱度去除率可达27%以上,单位能耗低至13 kWh/kg;商用阻垢剂对电解效果具有阻碍作用。

量子防垢技术在油田加热炉的防垢应用研究

加热炉是油田生产运行中的重要设备,结垢不仅会造成加热炉频繁清洗,增加检修成本,而且影响换热效率,减少使用寿命,甚至造成加热炉烧损,导致停产或停输。采用新型管道外置安装量子环防垢器防垢技术,释放有针对性的振动波改变水中钙镁离子的振动特性,减少加热炉在温升过程中CaCO_(3)的结晶和沉积,防垢率可以达到80%以上。量子环防垢器防垢技术对于减少加热炉清洗,提高加热炉炉效和使用效率有着积极的意义,可在油田结垢严重区块推广应用。

一种新型绿色荧光阻垢剂的制备与研究

由姜黄素(Cur)、马来酸酐(MA)和对苯乙烯磺酸钠(SSS)合成了一种绿色荧光阻垢剂聚(马来酸酐-对苯乙烯磺酸钠)接枝姜黄素(PMS-g-Cur聚合物)。利用傅立叶红外光谱仪(FTIR)对PMS-g-Cur的结构进行了表征,成功合成了目标产物。采用荧光光谱仪对其进行分析,荧光光谱显示PMS-g-Cur有望实现在线检测。静态阻垢实验表明,在70℃时,PMS-g-Cur阻CaSO4垢的效率可达到99.5%,阻CaCO_(3)垢的效率可达到82.8%。此外,还讨论了阻垢剂浓度、温度、pH值和矿化度对阻垢性能的影响,结果显示,阻垢剂具有一定的耐高温和耐盐性能。

ZCUP-3新型阻垢剂研究与应用

近些年,随着镇原油田的持续开发,注水时间增长,致使井筒自然结垢速度加快,结垢井数逐年上升,主要集中在镇252、镇287、镇277及镇28等区块,垢型主要以碳酸钙为主。经现场试验,现有4种阻垢剂对碳酸钙垢未产生良好的效果,因此基于垢型分析,实际生产数据等,研制出ZCUP-3新型阻垢剂。目前ZCUP-3阻垢剂在三个区块共计154口井投加,结垢速率由3.14 mm/a下降至1.41 mm/a,平均延长检泵周期184天,结垢导致检泵共减少48井次,实验结果良好。本文从该化学药剂成分入手,揭示其阻垢机理,并结合投加前后作业起出管柱情况进行了试验效果分析及经济效益评价。

阻垢剂在低温多效海水淡化装置中的工业化应用

目前我国低温多效海水淡化水处理药剂基本为国外公司垄断,价格昂贵。国产海水淡化阻垢缓蚀剂也正在突破瓶颈,质量、性能日渐成熟,但是缺乏统一、完善系统的方法验证,同时缺乏大型海水淡化工程考核验收平台,导致海水淡化水处理药剂价格居高不下。为打破国外垄断,提升我国海水淡化药剂自主创新能力和核心竞争力,并降低药剂使用成本,采用2.5万t/d低温多效海水淡化装置,开展了SD210阻垢剂在工业化试验装置中应用研究。试验结果表明:在为期2个月的试验期内,在SD210投加质量浓度为4~8 mg/L条件下,装置运行安全、平稳,无明显结垢和腐蚀现象;且海水淡化装置产品水水质优于《生活饮用水卫生标准》(GB 5749—2006)所规定的指标要求。综上,SD210阻垢性能良好,能满足低温多效海水淡化装置使用要求。

膜阻垢剂及其阻垢机理研究新进展

由于水资源紧缺的问题,反渗透膜处理技术发展迅速。膜阻垢剂因能减缓膜组件的结垢、提高水净化效率,因而被广泛应用于反渗透膜处理技术。常见的膜阻垢剂有磷酸盐类、阴离子聚合物类、阳离子聚合物类以及绿色阻垢剂等,一般认为它们可以通过螯合、分散、晶格畸变等作用或阈值效应阻碍或缓解垢的形成。树枝状聚合物膜阻垢剂具有优异的阻垢性能,与其结构相似的球形聚电解质刷作为一种刷状聚合物膜阻垢剂也在膜处理领域中崭露头角。深入研究新型膜阻垢剂的阻垢机理可为设计开发针对性强、经济环保的高效阻垢产品奠定理论基础。

耐高温阻硅垢荧光缓释微球的制备与缓释特征

缓释型阻垢剂常用来延长阻垢剂作用距离和时间,但在地热开采等高温循环水中,常规缓释技术释放速度过快导致效果不佳。为增强高温下的缓释效果,本文以耐热材料聚苯乙烯为壁材,以固相/油相/水相溶剂挥发法制备新型阻垢缓释微球,优选了芯材和乳化剂,探究了制备工艺,并利用荧光技术测试了缓释效率和阻垢效果。结果表明:硅藻土和十六烷基磺酸钠分别适宜用作固相吸附材料和乳化剂;乳化剂浓度为2%,芯材浓度为50 mg/mL,搅拌速度300 r/min为最佳制备条件。制备的微球静态释放时间长达100 h,动态释放时间超过20 h, 20 h阻垢率50%以上。本成果有望为高温循环水提供新型缓释阻垢技术。

西北地区某市地下水供水管网黄水产生原因分析与控制技术中试研究

随着供水管道使用年限的增加,管网逐渐老化,管网化学稳定性问题日益突出。为解决西北地区某市高碱度地下水供水管网黄水问题,保障用水安全,开展了黄水产生原因分析与控制技术中试研究。一方面,监测黄水形成过程中水质特点和规律,对铸铁管腐蚀管垢成分进行分析,探明黄水形成原因。另一方面,搭建管网中试系统,研究了余氯、碱度、缓蚀剂对管网铁释放的影响。结果表明:黄水形成存在周期性规律,形成原因为水力冲刷增强导致管垢中的铁释放到水体中,水体存在一定的腐蚀性也会影响铁释放。管垢主要成分为Fe3O4和α-FeOOH,但不同管垢层形貌特征及化学组成存在差异。建议该地区管网余氯浓度控制在0.4 mg/L左右,余氯较高或较低均会促进铁释放。综合考虑效果和经济性,应对突发性黄水问题时,建议优先采用0.5 mg/L(以P计)的三聚磷酸钠作为缓蚀剂投加控制黄水现象。每吨水需增加药剂成本约为0.018元。

接枝不同种类氨基酸对聚天冬氨酸阻垢剂阻垢性能的影响

在油田生产过程中结垢问题给油田企业带来巨大损失。常见的处理结垢的方法大致分为物理法、工具法和化学法。采用物理法、工具法处理结垢问题存在费用高、垢物清除效率低等缺陷,化学法因其操作简单、用量少、效果好等优点而被广泛采用。近年来,随着人们对环境保护意识的增强,聚天冬氨酸类阻垢剂被广泛研究。以马来酸酐和碳酸铵为原料合成了聚琥珀亚酰胺(PSI),在此基础上接枝丝氨酸、谷氨酸、酪氨酸并研究其阻垢性能。结果表明:谷氨酸接枝改性聚合物(GUL-PASP)阻垢效率为100%,具有优异的阻垢性能。

海上高温油田防垢剂的研制及应用

针对南海某油田因高温、高矿化度、高二氧化碳造成水处理系统低压段结垢严重的问题,制备了耐高温的防垢剂聚环氧琥珀酸(PESA),并与氨基三亚甲基膦酸(ATMP)、2-膦酸丁烷-1,2,4-三羧酸(PBTCA)进行复配,得到复合防垢剂,分别采用滴定法和纳米粒度及Zeta电位分析仪测定防垢率和水中垢的平均粒径。结果表明,当温度为98℃、PESA∶ATMP∶PBTCA为6∶2∶1、加量为10 mg·L^(-1)时,复合防垢剂的防垢率达到99.8%,水中垢的平均粒径为601.0 nm,PESA、ATMP、PBTCA具有良好的协同作用。现场应用结果表明,加注复合防垢剂后,防垢挂片未发现结垢现象,下游水样中Ca^(2+)浓度与地层水水质分析结果基本一致,防垢效果优于现场用防垢剂。

钇锆双金属MOFs对有机膦阻垢剂HEDP的吸附研究

采用溶剂热法首次合成了新型钇锆双金属有机框架(YZr-MOF)吸附材料,并对其结构和表面性质进行了表征,研究了YZr-MOF对有机膦阻垢剂羟基亚乙基二膦酸(HEDP)的吸附行为和性质。实验结果表明,YZr-MOF呈现出大小均匀的球形颗粒结构,比表面积为912.862 m^(2)/g;在298 K时,YZr-MOF理论最大吸附量为66.293 mg/g(以P计)。吸附过程符合准二级动力学和Langmuir模型,吸附过程为吸热过程,温度升高有利于YZr-MOF吸附HEDP。在吸附实验中,YZr-MOF的最佳质量浓度为0.2 g/L;YZr-MOF在较宽的pH范围内有着良好的稳定性,并且经过6次循环后,仍保持显著的吸附率。结合相关实验和FTIR、XPS的表征结果表明,静电作用和配体交换为主要吸附机理。

MA/AA/DETA三元共聚物缓蚀阻垢剂的制备及机理研究

以马来酸酐(MA)、丙烯酸(AA)、二乙烯三胺(DETA)为单体,过硫酸铵为引发剂合成了MA/AA/DETA三元共聚物缓蚀阻垢剂。通过正交实验确定的优化条件为:m(MA)∶m(AA)∶m(DETA)=10∶14∶5,反应温度(80±5)℃,反应时间6 h,阻垢率大于80%,缓蚀率大于85%。利用静态结垢法、SEM扫描电镜、动态腐蚀仪和电化学工作站评价缓蚀阻垢剂的缓蚀阻垢机理,结果表明:阻垢机理主要有螯合作用、分散作用、晶格畸变作用,通过共聚物吸附在金属表面形成保护膜,减少腐蚀因素与金属表面的接触。