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.

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.

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.

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.

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.

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.

Synthesis and Inhibition Efficiency of a Novel Quadripolymer Inhibitor

A novel quadripolymer scale inhibitor poly-maleic anhydride-acrylic acid-acrylamide-sodium methallyl sulfonate(PMAAS)was synthesized by solution polymerization with maleic anhydride(MA),acrylic acid(AA), acrylamide(AM),sodium methallyl sulfonate(SMAS),etc.IR spectrum shows that PMAAS contains carbonyl, hydroxyl,phosphatic and sulfonic acid group.SEM indicates that PMAAS blocks the normal growth of scale CaCO3 and CaSO4 crystals.The influences of PMAAS concentration,Ca 2+ concentration,temperature and pH value of the system on the inhibition efficiency are investigated.The inhibition efficiency of PMAAS is superior to com- mercial inhibitors T-225 and XF-192.

Study of the Inhibitor Scaling Effect of the Agricultural Water by a Phosphate Fertilizer

The localised irrigation or drop by drop system is a technique which makes it possible to save water, because it ensures a balanced and efficient distribution of water and an effective fertilization. However, this ferti-irrigation system is facing a number of problems hindering the agricultural development. The lack of uniformity of the localised irrigation was observed and found out that it is due to chemical clogging of drippers. Considering the complexity of the composition of the natural water used in micro-irrigation, we started our study by examining the effectiveness of the inhibitor on pure calco-carbonic water with 40°F, and then moved to explore the natural water of the agricultural region. The Legrand-Poirier-Leroy method allowed us to determine the position of the irrigation water compared to calco-carbonic balance. LCGE (abbreviation of “Laboratory of Chemistry and Environmental Engineering”) technique, based on the accelerated formation of calcium carbonate deposit under the effect of a degasification of studied water, enabled us to evaluate the scaling power of this water of irrigation either with or without inhibitor. The experimental results showed the following: in the case of pure calco-carbonic water with 40?F and of natural water, the addition respectively of 2 mg/L and 2.25 mg/L of phosphate fertilizer completely inhibits the precipitation of calcium carbonate under the conditions of the experiment.

The Evaluation Principles,Indicator System and Methods for Environment-friendly Utilization of County-level Land Resources

From the perspective of environmental issues concerning land use and importance of county,we analyze the great significance of environment-friendly use of county land resources. On the basis of discussing the concept and connotation of environment-friendly utilization of land resources,we build the basic framework for the evaluation of environment-friendly utilization of land resources from environment,economy and society,and propose the evaluation methods combining composite index method and multi-angle single indicator evaluation method. At the same time,we establish the grading system and grading standards for environment-friendly county land use,to promote the qualitative and quantitative evaluation of environment-friendly county land use.

Proton pump inhibitor step-down therapy for GERD:A multi-center study in Japan

AIM:To investigate the predictors of success in stepdown of proton pump inhibitor and to assess the quality of life(QOL).METHODS:Patients who had heartburn twice a week or more were treated with 20 mg omeprazole(OPZ) once daily for 8 wk as an initial therapy(study 1).Patients whose heartburn decreased to once a week or less at the end of the initial therapy were enrolled in study 2 and treated with 10 mg OPZ as maintenance therapy for an additional 6 mo(study 2).QOL was in-vestigated using the gastrointestinal symptom rating scale(GSRS)before initial therapy,after both 4 and 8 wk of initial therapy,and at 1,2,3,and 6 mo after starting maintenance therapy.RESULTS:In study 1,108 patients were analyzed.Their characteristics were as follows;median age:63(range: 20-88)years,sex:46 women and 62 men.The success rate of the initial therapy was 76%.In the patients with successful initial therapy,abdominal pain,indigestion and reflux GSRS scores were improved.In study 2,83 patients were analyzed.Seventy of 83 patients completed the study 2 protocol.In the per-protocol analysis,80%of 70 patients were successful for stepdown.On multivariate analysis of baseline demographic data and clinical information,no previous treatment for gastroesophageal reflux disease(GERD)[odds ratio (OR)0.255,95%CI:0.06-0.98]and a lower indigestion score in GSRS at the beginning of step-down therapy(OR 0.214,95%CI:0.06-0.73)were found to be the predictors of successful step-down therapy.The improved GSRS scores by initial therapy were maintained through the step-down therapy.CONCLUSION:OPZ was effective for most GERD patients.However,those who have had previous treatment for GERD and experience dyspepsia before stepdown require particular monitoring for relapse.

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。

含硅型碳酸钙垢防垢剂SMAA的研究

采用水溶液自由基共聚法,以次磷酸钠(SHP)、顺丁烯二酸酐(MA)、2-丙烯酰胺基-2-甲基-1-丙磺酸(AMPS)、乙烯基三甲氧基硅烷(A171)为原料、2,2′-偶氮双(2-甲基丙脒)二盐酸盐(V50)为引发剂,合成了一种新型含硅聚合物防垢剂SMAA,并利用FTIR、^(1)H NMR和XPS对其结构进行表征。结果表明,最优合成条件为:单体配比n(SHP)∶n(MA)∶n(AMPS)∶n(A171)=10∶30∶10∶1,引发剂加量为1.0%,反应温度为80℃,单体浓度为25%,聚合反应时间为5 h。在评价温度为70℃、加量为50 mg/L时,防垢率可达92.9%。利用SEM、XRD和TEM对防垢剂SMAA作用于碳酸钙的机理进行研究,防垢剂SMAA的防垢机理是使碳酸钙晶体发生晶格畸变,阻碍碳酸钙晶体的聚集增大,对已形成的碳酸钙微晶进行包覆。

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。

产水气井碳酸钙阻垢剂分子模拟研究

为了解决西南油气田分公司磨溪气田龙王庙组地层水矿化度高、结垢离子多导致油管经常发生碳酸钙结垢堵塞的问题,采用分子动力学模拟阻垢剂与钙离子和碳酸根离子相互作用过程,分析阻垢剂阻止碳酸钙垢的机理。在不同温度条件下分别模拟了水溶液中三聚磷酸钠和羧甲基葡聚糖阻垢剂阻止钙离子与碳酸根离子生成碳酸钙垢的过程,明确了阻垢剂与结垢离子的作用方式、阻止机理。分子模拟结果表明:碳酸钙垢的生成主要以钙离子或碳酸根离子为中心,钙离子与碳酸根离子相互吸引,当结垢阴阳离子距离达到0.25 nm后就会生成碳酸钙分子,碳酸钙分子不断聚集形成晶体,温度越高越容易结垢;阻垢剂的阻垢机理是阻垢剂的阴离子对钙离子吸引力更大,从碳酸根离子与钙离子在距离为0.25 nm的结合概率降低可以得到证明,溶液中阻垢剂阴离子之间相互排斥,垢分子与离子相对分散,碳酸钙无法聚集形成晶体;三聚磷酸钠阻垢剂的阻垢效果比羧甲基葡聚糖(CMD)阻垢剂更好,温度越高垢分子的生成概率越低,三聚磷酸钠最大概率密度比羧甲基葡聚糖(CMD)阻垢剂的小0.415倍;三聚磷酸钠阻垢剂阴离子负价高,相互排斥,造成溶液中所有阴阳离子更分散,垢分子难以聚集形成碳酸钙晶体;采用该分子模拟方法可以筛选适合的阻垢剂。

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。

延长油田低渗油藏分层注水缓蚀阻垢剂的制备及性能研究

本文以丙烯酸(AA)、顺丁烯二酸钠(MAH-Na)、乙烯吡咯烷酮(NVP)及自合成的季铵化咪唑啉(QIM)为单体,采用偶二异丁眯盐酸盐(V50)紫外光引发体系合成了四元共聚缓蚀阻垢剂。通过正交实验筛选出最佳单体配比为18∶6∶3.5∶2.5,结合静态结垢实验、动态腐蚀实验以及分子量测试得出最佳合成条件为:V50加量为0.6wt%、反应时间为8h、单体浓度为35wt%,此最佳条件合成的缓蚀阻垢剂的缓蚀率达86.1%,CaCO_(3)阻垢率达91.2%,CaSO_(4)阻垢率达96.1%,BaSO_(4)阻垢率达73.2%,各项性能优于市场采购的单一功能缓蚀剂与阻垢剂。

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。