油田化学清防蜡技术研究综述

影响原油结蜡的因素主要包括原油构成(蜡含量、原油组分、胶质和沥青含量)、环境条件(温度、压力、流速)、原油中杂质情况(机械杂质、水)等。针对结蜡问题,目前采用的蜡沉积控制方法可分物理、化学、生物三种,其中化学方法因具有操作便捷、经济适用、可有效适用于各种生产需求等多项优势,被广泛应用。化学蜡沉积控制可以分为清蜡和防蜡两个方面。化学清蜡技术是利用清蜡剂将蜡沉积物溶解,使其从设备表面剥离,再通过油流冲刷带走,主要研发方向是根据生产需要组合不同功能组分,开发具有良好应用性能的复合乳液型清蜡剂。化学防蜡技术是通过防蜡剂破坏蜡晶结构、干扰蜡晶聚集、改变蜡晶及结蜡表面的性质从而预防结蜡的发生,主要研发方向是根据结蜡性质合成适用性好的高分子聚合物防蜡剂,并与表面活性剂、稠环芳烃、碱剂等功能组分协同应用。此外,研发并应用能够实现“防清结合、一剂多效”的清防蜡剂,可大幅延长清蜡周期、降低清蜡难度,实现节约开发成本、保障油田生产稳定的根本目标。     

水基蜡晶改进剂型防蜡剂的研制与应用

为了克服油基清防蜡剂存在的有毒、易燃、密度小等缺点,解决水基清防蜡剂存在的清蜡效率低、防蜡效果差及乳液型防蜡剂稳定性差等不足,利用表面活性剂亲水亲油基团结构特点,将蜡晶改进剂均匀地分散在水中,研究出具有低毒不易燃烧、密度较大、清蜡效率高、防蜡效果好等优点的水基蜡晶改进剂型防蜡剂。室内实验表明,该防蜡剂在最佳的配比条件下,降黏率和动态防蜡率大于70%。现场试验表明,采用连续加药方式,可有效减少洗井次数,提高油井产油量。     

宁东油田清蜡、防蜡技术分析

在原油开采过程中,随着温度、压力的降低和气体的析出,溶解的石蜡便以结晶体析出、逐渐长大聚集最终沉积在管壁等固相表面上,即出现所谓的结蜡现象.结蜡会堵塞产油层,降低油井产量,同时也会增大油井负荷,造成生产事故.油井结蜡是影响油井高产、稳产的主要因素之一,清蜡和防蜡是高含蜡油井常规管理的重要内容.通过收集整理现场资料、分析原油性质和综合评价不同清防蜡技术的经济效果,确定宁东油田采用热力清蜡和化学防蜡技术较为合适.     

油井特种合金防蜡技术研究与应用

帅垛油田油井结蜡问题日益突出,已严重制约其效益开发。前期采用的机械清蜡、热力清防蜡和化学药剂清防蜡等工艺技术存在成本高、效率低、安全性差和污染地层等不足。鉴于此,研发了油井特种合金防蜡技术。阐述了特种合金防蜡装置的结构、防蜡机理及性能特点,并对该防蜡装置的关键结构进行了设计。通过开展降凝降黏试验,优化了特种合金方案,以适应帅垛油田原油物性。试验及应用结果表明:优化后的特种合金防蜡装置可使原油凝点降低2～3℃,在42～60℃范围内黏度均有所降低,最大降黏率达到80. 38%;帅垛油田4口油井结蜡速度均变缓,清蜡周期比优化之前延长2倍以上,原油黏度下降30%以上,凝点下降幅度大于2℃,检泵周期较之前得到有效延长。油井特种合金防蜡技术的研发成功为帅垛油田油井清防蜡工艺提供了新的技术支持。     

延长油田高含蜡原油防蜡剂筛选

针对目前延长油田油井结蜡现状,筛选出了适用于延长油田原油的酯基防蜡剂,复配防蜡剂CH-1：CH-2=1：2,最佳加量为2 000 mg/L,其防蜡率满足实际需要.对延长原油的加剂前后原油的粘温性以及加剂前后原油的流变性的研究发现,该防蜡剂能使延长原油原有的粘度及剪切应力减小,利于原油的流动并达到防蜡目的.对加剂前后原油的显微结构分析发现,加入防蜡剂后含蜡油中的蜡晶消失,说明新型防蜡剂有抑制固相基团沉积的能力.     

YS-3新型清防蜡剂的研制及现场试验

采油三厂原油是高含蜡原油,结蜡问题给采油和运送带来困难。研发了一种减黏型防蜡、清蜡剂,该剂可防止黏稠度高的原油在采油管上结蜡,并兼有清蜡、减黏作用。可代替原PR-PI-C3型液体防蜡剂防蜡率低(≤40%)、溶蜡速率低(g/70min)、凝固点高(-4℃),冬季加药困难,油井防蜡效果差,热洗周期短。自2003年9月起,针对盘古梁油田结蜡严重、热洗频繁的盘58-27和盘59-25两个井组10口井应用YS-3清防蜡剂,试验结果表明,该剂的防蜡率≥40%。可在-20℃低温下使用和存放,现场加剂量100～120 mg/L。防蜡周期可达9个月以上,并且具有流动性好,加药工艺简单,成本低,清、防蜡效果显著的特点。     

保护层分析方法研究及其在风险分析中的应用

在结蜡油井中使用固体化学防蜡剂,可有效抑制油井管、杆、泵等处结蜡,延长有杆泵的检泵周期,降低抽油机能耗。用动态结蜡率测试仪及流变仪分别测试防蜡率及析蜡点的变化,评价防蜡剂在室内的应用效果。通过室内理论计算检泵周期、溶解速度、防蜡率之间的关系,预测了防蜡剂在井底的有效性。用抽油机系统效率测试仪,测试抽油机电机运行的电能参数及安装在抽油机悬绳器上的传感器的油井载荷,对比结蜡井措施前后的数据,评价防蜡效果。测试表明,结蜡井使用化学固体防蜡剂可使油井载负荷平均下降9.73kN,系统效率提高6.92%,综合节电率22.23%。     

华北某区块井筒结蜡原因分析及结蜡程度预测

针对华北某区块油井井筒下部尾管及泵口处结蜡严重的现象,采用多种材料表征手段对结蜡原油和蜡沉积物进行分析,探究该区块井筒的结蜡原因,选取单井日产液量、原油黏度、原油含水量等因素作为影响蜡沉积的自变量,结蜡程度作为因变量,采用布谷鸟算法（CS）优化支持向量机（SVM）对数据进行回归,预测不同油井的结蜡程度。结果表明,该区块原油为高含蜡原油,且原油中重组分较多,沥青质和机械杂质高于其余区块,可作为析蜡中心加速蜡晶析出;从井口到井底,蜡沉积物的相关物性呈纵向分布特征,蜡沉积物中的长直链烷烃越多,平均分子量越大,熔蜡点越高,导致清防蜡困难;通过结蜡程度预测,CS-SVM模型可准确预测结蜡程度,平均相对误差小于5%。研究结果可为类似区块油井清防蜡措施的制定提供实际参考。     

AD-4微生物防蜡剂培育与应用

介绍了微生物防蜡剂的培育、室内性能检测及现场防蜡试验过程。用现场油水样中菌种驯化的菌种和实验室菌种配伍、优化、筛选,培育成AD-4微生物防蜡剂。通过室内试验验证,AD-4微生物防蜡剂对现场蜡块的乳化降解作用使蜡块凝固点降低4~8.5℃,原油培养液表面张力降低率30.3%~49.3%,黏度降低35%~50%,原油流动性得到了很大的提高。经现场12口油井试验证明,应用AD-4微生物防蜡剂后,油井电流、负荷下降,示功图显示结蜡现象明显减轻,检泵周期延长,部分井检泵周期可延长到原来的2倍,投入产出比可达1:2.8。     

一种乳液型清防蜡剂的研制及现场应用试验

针对新安边区块油井原油性质、蜡质特点及油井结蜡规律,研制开发出一种乳液型清防蜡药剂,该药剂的溶蜡率为0.025 g/min、防蜡率为38.53%,且稳定性良好。对新安边4口高含蜡油井的现场应用结果表明,该清防蜡剂可使抽油井平均清蜡周期从1.57月/次延长到5.2月/次,单井清蜡次数平均减少5.3次/年,应用效果显著。     

Paraffin Deposition Mechanism and Paraffin Inhibition Technology for High-carbon Paraffin Crude Oil From the Kazakhstan PK Oilfield

The compositions and structure of the Kazakhstan PK crude oil is analyzed in the methods of GC, ¹H-NMR, and DSC. It was found that the main reasons for paraffin seriously depositing on the well wall were the higher carbon numbers in the paraffin molecule, lower branched-chain degree in the paraffin molecule, the lower content ratio of asphaltene and resin to paraffin, wellhead temperature being lower than paraffin-appearing temperature, the higher gas-oil ratio, and lower water cut in the produced liquid. A new paraffin inhibitor whose paraffin inhibition rate is above 60% for the Kazakhstan PK crude oil was developed. Its paraffin inhibition mechanism is researched by using microscope and contact angle instrument. The paraffin inhibition mechanism is mainly to prevent formation of paraffin crystal with network structure by modifying paraffin crystals structure and to form the surface against paraffin deposition by changing the wettability of the paraffin deposition surface.     

Experimental Investigations of the Mitigation of Paraffin Wax Deposition in Crude Oil Using Chemical Additives

Abstract

Wax deposition from crude oil is a very expensive problem for oil producers around the world. The objective of this study is to understand the characteristics of paraffin wax deposition and to test the effectiveness of solvents in the inhibition of the crystallization and subsequent precipitation of the paraffin wax and to test the most effective concentration of the solvent used. The oil used here is from the Dakota formation from the Fourteen Mile Field in the Big Horn Basin of Wyoming. Two paraffin inhibitors were tested for this crude oil on a horizontal flow system. The inhibitors are mixtures of solvents, pour point depressants, and wax crystal modifiers. These inhibitors were tested at different concentrations and temperatures and the deposition rates were obtained for each. One inhibitor especially designed for this crude oil was relatively successful, reducing the deposition by up to 59% depending on the temperature.     

热处理对添加防蜡剂长庆原油流动性及蜡沉积特性的影响研究

基于流变性测试和蜡沉积实验研究了热处理温度对添加EVA/PAMSQ复合防蜡剂的长庆原油的流动性和蜡沉积特性的影响。研究发现加剂原油依然具有热处理效果,50℃热处理条件下加剂原油的流动性改进效果较差,随着热处理温度升高至60、70和80℃,加剂原油的流动特性(如凝点、黏度、小振幅振荡剪切特性)显著改善。80℃热处理条件下,加剂原油的凝点已低于0℃,表明热处理与EVA/PAMSQ复合防蜡剂具有良好的协同效果。同时,随着热处理温度的升高,加剂原油的蜡沉积速率逐渐降低,但蜡沉积物的含蜡量逐渐升高,这可能不利于蜡沉积物的剥离。蜡沉积物呈现出非均质结构,表层蜡沉积物为凝油状,底层蜡沉积物具有比表层蜡沉积物更高的析蜡点和屈服强度。     

长庆白豹油田固体防蜡技术研究

长庆白豹油田在油田的开发过程中存在着比较严重的结蜡问题,影响原油的正常生产。本文分析了白豹油田结蜡井的原油和蜡样:结蜡井原油中蜡含量高,在15%~20%,胶质和沥青质含量相对较小;蜡样碳数分布主要集中在C26~C39,以微晶蜡为主。应用原油动态结蜡率测试仪和流变仪两种方法测试了MH化学固体防蜡器的性能,它能降低高含蜡原油粘度>80%,降低原油凝点达11℃,防蜡率可达到75%以上。MH化学固体防蜡器在白豹油田现场试验15口油井。现场试验表明,化学固体防蜡器应用后,抽油机载荷明显低于加药前,且能有效地减少常规的清防蜡作业,延长检泵周期。     

Inhibition of deposits of high-molecular weight paraffins in oil wells

Crudes from the Shengli and Tuha oil fields (China) and the PetroKazakhstan oil field (Kazakhstan) containing macromolecular paraffins were investigated by gas chromatography, ¹H NMR spectroscopy, etc. The mechanism of inhibition of the paraffin deposits in the wells in these fields was investigated by microscopic studies and measurement of the contact angle of wetting of steel with water. It was shown that a low content of asphaltenes and resins in the crude, high gas:crude ratio in the field, high molecular weight of the paraffins with low branching of their molecules, and a temperature in the wellhead lower than the initial crystallization temperature of the paraffins are the basic causes of deposition of macromolecular paraffins. The effectiveness of inhibition of paraffin deposits in such crudes is greater than 60%. The mechanism of inhibition consists of preventing formation of a three-dimensional structure in the paraffins and depositing them on the surface by modifying the structure of the paraffin crystals and changing the wettability of the surface of steel with water.     

Influencing factors governing paraffin wax deposition of heavy oil and research on wellbore paraffin remover

Abstract

Wax deposition is harmful to oil wells, especially for waxy heavy oils at low temperature. The influencing factors on wax deposition of heavy oil were studied and a kind of O/W emulsion type wellbore wax remover was investigated. The results showed that the wax deposition rate of Jinghe heavy oil increased with the increasing wax content and asphaltenes content but decreased with the increasing water content. The oil in water emulsion type paraffin remover was prepared and it showed both good wax dissolution and paraffin prevention ability and can save large quantities of solvent. The results of this study provides a possible way for waxy heavy oils to dissolve wax, to prevent wax deposition and reduce the viscosity of heavy oils by emulsification together, which is helpful to reduce the frequency of hot washing and enhance oil recovery for waxy heavy oils.     

Study on paraffin wax degrading ability of Pseudomonas nitroreducens isolated from oil wells of Gujarat,India

Microbial remediation is an efficient method of removing paraffin wax from oil wells and pipelines and is found to be environment friendly and economical. In this study, a potential paraffin wax degrading bacterial strain was isolated from oil wells of Gujarat and was identified as Pseudomonas nitroreducens by 16S rRNA sequencing. Pseudomonas nitroreducens showed 100% utilization of heneicosane, 79.74% utilization of pentacosane and 72.50% utilization of triacontane, the major components of paraffin wax in 8 days at 37°C. Pseudomonas nitroreducens degraded 70% of paraffinic crude oil in 10 days at 37°C. The probable end products formed after degradation of eicosane and heneicosane by Pseudomonas nitroreducens were analysed by Mass Spectrum. The above results proving isolate as a potential candidate for degradation of paraffin wax in oil wells.     

An Evaluation of the Performance of Selected Wax Inhibitors on Paraffin Deposition of Nigerian Crude Oils

Paraffin deposition in oil production constitutes a critical and difficult to control problem, in terms of productivity and production operation costs, going from the reservoir to surface facilities. In Nigeria, operators spend millions of dollars each year to control the deposition of paraffin and to deal with other paraffin deposition related problems. Expenditures of this magnitude obviously have a significant impact on profits. The main purpose of this work is to assess the net effect of many commercial wax inhibitors on paraffin deposition from a wide range of waxy crude oil systems in Nigeria for the selection of an efficient additive. Deposition from a wide range of waxy crude oil systems from Nigerian oilfields were examined with and without chemical wax deposition inhibitors. The devices used to produce the deposits investigated were cold spot and dynamic flow wax deposition apparatus capable of producing field-like deposits with relatively small volumes of oil in minutes. Results show that most of the commercial wax inhibitors tested could decrease the deposition of wax, but none has the economical capability to solve the paraffin deposition problem for an extended period of time. One intriguing result was that the addition of xylene improved the performance of three wax inhibitors tested. It was also observed that there are subtle differences in inhibitor performance depending on deposition tendencies of crude oil.