聚长链α-烯烃减阻性能的影响因素研究

利用室内环道评价装置考察了聚长链α-烯烃减阻剂的溶解时间、雷诺数、加剂浓度、黏均相对分子质量和高聚物的抗剪切能力对减阻性能的影响。结果表明：聚合物的减阻率随溶解时间的延长而增大,达到一定值后趋于稳定;聚合物的凝聚状态以及颗粒的分散程度对减阻剂的溶解能力影响较大;加剂浓度在15 mg/L时减阻率达到最大值,加剂浓度与减阻率的关系基本符合Virk经验公式;存在最佳雷诺数,雷诺数大于或小于最佳雷诺数时,减阻能力减弱,直至无效;在一定的相对分子质量范围内,黏均相对分子质量与减阻率呈线性关系,相对分子质量越大,减阻率越好;聚合物经过齿轮泵剪切后会使减阻率急剧下降,经过管壁的初次剪切也会使减阻率下降40%左右。     

聚甲基丙烯酸癸酯溶液的减阻性能和抗剪切性能的研究

本文采用 GPC,旋转粘度计和循环管路装置研究了聚甲基丙烯酸癸酯(PDMA)煤油溶液的流变性、减阻性和抗剪切性。实验证明,浓度为0.01%—10%的煤油溶液均是假塑性流体,其流动行为可用τ=K(?)~n 来描述;发现在降温过程中,浓度大于3%的溶液有相分离现象出现,相分离点随浓度增大而升高。PDMA 在煤油中的减阻百分率(DR)随分子量和壁切应力增大而增大。当分子量和壁切应力(τ_w)分别增大到一定值(M_m 和τ_(wm))后,减阻百分率达到最大值(DR_m),以后不再增高。M_m 随浓度增大而减小,但不随τ_w 而变化;DR_m 随τ_w 和浓度增大而增大;在湍流过程中,PDMA 的力学降解过程可用 M=Aexp(-Kt)+M_∞来描述;K 随τ_m 增大而增加,但随浓度增加而减小;M_∞随浓度增大而增大,随τ_w 增大而减小,不随起始分子量 M_o 而变化。     

减阻剂减阻效果的评价与分析

针对临邑-濮阳管道添加HG减阻剂的输油工况,建立并运用旋转圆盘装置进行了管输原油加剂模拟实验。对临濮线加HG减阻剂的减阻效果和影响因素进行了分析,确定了减阻率与雷诺数;减阻率与剪切强度;减阻率与加剂浓度;减阻率与输油温度等关系,为减阻剂减阻效果的评价和研究提供了一种新的方法。     

原油输送减阻技术与减阻效率

原油在管道中输送时,加入少量ppm的减阻剂,增输量可达到10%以上。用作减阻剂的油溶性聚合物,分子量一般高达几百万到上千万。按分子数计算,减阻剂在原油中占的比例微小,因此不会改变原油的粘度。减阻效率决定于聚合物在溶液中的形态,空间尺寸,聚合物的溶解性能以及使用减阻剂的技术。实验表明(1)减阻效率随减阻剂添加量而增加,但减阻剂浓度达到一定值后,减阻率提高缓慢;(2)流体的流速增加,使减阻效率显著增加,但对不同的聚合物影响结果不一样;(3)在管径相同的条件下,流体的雷诺数增加,减阻效率增加;(4)在一定范围内壁剪切应力增加,减阻率也随之增加,但过大的剪切力会使高聚物降解,分子量降低,减阻率下降;(5)原油中含微量水份会影响减阻率。当含水量超过一定值时,因聚合物溶解性不好,反而导致减阻剂失效。目前工业上使用的减阻剂品种主要是超高分子量的聚α—烯烃,在油中的添加量为φn×10ppm以内,使减阻率在20%左右,增输15%左右,可以明显增加经济效益。     

悬浮型减阻剂的配方研究

依据溶度参数理论,通过模拟软件和实测方法对部分醇和醇醚进行筛选,得出合适的悬浮型减阻剂主悬浮介质;根据影响悬浮型减阻剂稳定的因素,对其存放稳定性和耐热性进行考察,得出合适的密度调节剂、乳化剂和增稠剂。由此确定悬浮型减阻剂的组成主要包括戊醇、乙二醇甲醚、span80、tween60、乙撑双硬脂酰胺、高聚物颗粒包覆剂等。对制得的悬浮型减阻剂的表观黏度、耐高低温性能及减阻性能等进行测定和评价,认为高聚物颗粒粒径和高聚物含量是影响其表观黏度的主要因素,减阻率随悬浮型减阻剂加入量的增大而增加,至最大值后变化趋于平缓。     

洪荆管线常温添加减阻剂输油试验

为了研究不同浓度减阻剂对沿程摩阻、管输量和管输效益的影响规律,在洪荆线采用常温添加减阻剂输送工艺进行输油试验。研究表明:洪荆线可采用常温加剂方式输送原油;添加减阻剂可减小洪湖站与新沟站之间的压降损耗,增加管输量;减阻剂浓度越大,两站之间的压降损耗越小,管输量越大;当减阻剂浓度继续增大时,增输和减阻效果减缓;添加减阻剂运行,可增加洪荆线管输收益;随着减阻剂浓度的增加,管输效益先增大后减小;减阻剂的添加浓度为30 mg/L时,可获得最大的经济效益。     

α-烯烃合成减阻剂的研究

在管输流体中加入减阻剂是提高输送能力的有效方法。以α-烯烃为原料,利用正交试验法确定减阻高聚物α-烯烃的最优配方和合成条件,分析了主催化剂、助催化剂用量、反应温度和反应时间等因素对聚合产物的影响程度,制定出可行的试验方案。在优化条件下合成的减阻剂,对于对0号柴油,流体雷诺数6000,添加量10μg/g时,减阻效果优于同类产品。     

页岩储层压裂减阻剂减阻机理研究

选择6种不同类型的减阻剂,通过研究不同浓度减阻剂的黏度和减阻效果,分析了减阻剂类型、分子量、分子结构、离子性能和浓度对其减阻性能的影响,并对减阻剂减阻机理进行了探索性研究。结果表明,减阻剂水溶液属于幂率流体,在一定流量范围内减阻率随着浓度的提高而提高;其水溶液黏度、离子特征和减阻率没有明显的联系,分子量在100万以上的减阻率在相同浓度下,减阻率趋于一致;影响减阻剂减阻性能的主要因素是减阻剂的分子结构。得出低分子量的长链结构的减阻剂和具有支链的长链结构的减阻剂以及具有柔顺、螺旋型分子链结构的减阻剂减阻性能更稳定;带支链的长链结构的减阻剂,在水中速溶,在较广泛的雷诺数范围内可得到理想的减阻率,具有较小的分子量,容易分解,对储层伤害小,此类减阻剂适合作页岩气储层大规模滑溜水压裂液的添加剂。     

α-烯烃合成减阻剂的研究

在管输流体中加入减阻剂是提高输送能力的有效方法。以α-烯烃为原料，利用正交试验法确定减阻高聚物α-烯烃的最优配方和合成条件，分析了主催化剂、助催化剂用量、反应温度和反应时间等因素对聚合产物的影响程度，制定出可行的试验方案。在优化条件下合成的减阻剂，对于对0号柴油，流体雷诺数6000，添加量10μg／g时，减阻效果优于同类产品。     

温度对聚α-烯烃合成减阻剂的影响

研究了起始温度、出料温度、通冷媒温度、停冷媒温度对聚α-烯烃合成减阻剂减阻率的影响,结合室内模拟环道评价装置和凝胶渗透色谱仪,测定了聚合物的减阻性能及相对分子质量和相对分子质量分布。结果表明,在起始温度3℃、出料温度9℃、通冷媒温度20℃、停冷媒温度10℃条件下,聚合物重均相对分子质量可达3×106,减阻率[ρ(聚合物)＝5g/m3]大于27%。     

Drag reduction and shear resistance properties of ionomer and hydrogen bond systems based on lauryl methacrylate

Based on molecular dynamics simulation results,a lauryl methacrylate polymer with drag reduction and shear resistance properties was designed,and synthesized by emulsion polymerization using 2-vinyl pyridine and methyl methacrylate as the polar polymerization monomer.After ionization of lauryl methacrylate polymer,an ion-dipole interaction based drag reduction agent (DRA) was obtained.The existence of ion-dipole interaction was proven through characterization of the drag-reducing agent from its infrared (IR) spectrum.The pilot-scale reaction yield of the DRA under optimum conditions was investigated,and the drag reduction and shear resistance properties were measured.The results show that:1) The ion-dipole or hydrogen bonding interaction can form ladder-shaped chains,therefore the synthesized DRA has shear resistance properties;2) The larger the molecular weight (MW) and more concentrated the distribution of MW,the better the drag reduction efficiency and the performance of the ionomer system was superior to that of the hydrogen bonding system;3) With increasing shear frequency,the drag-reduction rates of both the DRAs decreased,and the drag reduction rate of the ionomer system decreased more slowly than of the corresponding hydrogen bonding system.From the point of view of drag reduction rate and shear resistance property,the ionomer system is more promising than the hydrogen bonding system     

双物料预聚法合成减阻剂及性能评价

采用可控予聚的方式合成了HG-2成品油减阻剂,聚合物的黏均相对分子质量大于3.0?106。 对柴油中加入50 mg/L HG-2减阻剂进行指标评价及台架试验和行车试验。结果表明：加入50 mg/L的减阻剂,对柴油性质影响不大,能符合GB252-2011普通柴油的要求;作为燃料,对车辆整体性能无明显的影响。在洛郑驻成品油管道进行了现场试验,加剂10 mg/L,柴油增输率可增加30.1%,加剂量8 mg/L,雷诺数为52 411,70 940,78 087时,对应的增输率分别为26.8%,30.2%,38.6%,增输效果较好。     

Friction pressure correlations for turbulent flow of drag reducing polymer solutions in straight and coiled tubing

Accurate determination of friction pressure losses of dilute drag reducing polymer solutions remains to be a challenge in many practical applications. These include a wide variety of hydraulic operations performed on a daily basis in the oil and gas industry. Most drilling, completions, and stimulation jobs require pumping fluids at high flow rates, which in turn generates high frictional pressure losses, enhanced by the use of small diameter tubing or coiled tubing. Curvature in this latter is believed to generate secondary flows and thus extra flow resistance. Therefore, good drag reduction characteristics of fluids are desirable.In this study, energy dissipation by eddies in turbulent flow of viscoelastic fluids is assumed to be the mechanism causing drag reduction. Various concentrations of Nalco ASP-700 and Nalco ASP-820 dilute polymer solutions are tested at ambient temperature in laboratory-scale and full-scale flow loops installed with straight and coiled tubing sections exhibiting different values of diameter, curvature ratio and pipe roughness. In addition, flow tests are conducted at 100 °F and 130 °F using the laboratory-scale flow loop.Effects of concentration, temperature, curvature ratio, and pipe roughness on drag reduction are discussed in light of Fanning friction factor versus solvent Reynolds number plots. Results show that drag reduction in coiled tubing is lower than in straight tubing. As curvature ratio increases, drag reduction decreases. The effect of increasing temperature is to decrease drag reduction in straight tubing and increase it in coiled tubing. In turn, the effect of increasing pipe roughness is to slightly decrease drag reduction in straight tubing up to a certain Reynolds number value and then it starts to increase. For coiled tubing, the effect of increasing pipe roughness is to decrease drag reduction.In this study, generalized correlations for the prediction of drag reduction in dilute polymer solutions flowing in straight and coiled tubing are developed on the basis of the energy dissipation of eddies in turbulent flow field and a shear rate dependent relaxation time. In addition, correlations are validated using experimental data for a low concentration guar fluid flowing through full-scale flow loop.     

天然气水合物储运天然气技术

随着世界能源需求的不断增长以及天然气资源的大力开发和利用,必然要求不断完善天然气储运技术。天然气水合物储运天然气技术具有安全可靠、成本低等优势,备受瞩目。概括了目前天然气主要的储运方式,简单介绍了天然气水合物的特性,从天然气水合物的制备、储存、运输、分解等几个方面分析了天然气水合物储运技术,比较分析了天然气水合物技术与其他天然气非管输技术的经济性。     

α-烯烃高分子减阻剂的性能研究

采用本体聚合法,以TiCl4为主催化剂、Al(i-Bu)3为助催化剂合成α-己烯/α-十二烯减阻剂.用IR,1 HNMR,TG等手段对聚合物结构进行表征,考察了主催化剂用量、助催化剂用量对减阻剂特性黏度的影响,并采用室内环道评价装置对减阻率进行测试.结果表明:在主催化剂用量为0.09 g、助催化剂用量为0.12 mL、...     

Drag reduction characteristics in straight and coiled tubing — An experimental study

An excessive friction pressure loss due to the small tubing diameter and curvature (which is believed to cause secondary flow) of Coiled Tubing (CT) often limits the maximum obtainable fluid flow rate in most CT operations. Good drag reduction property becomes a desirable quality for drilling, completion and workover fluids for CT applications. Yet, the drag reduction phenomenon in coiled tubing has not been well understood.This paper presents an experimental study of drag reduction performance of commonly used drag reducing agent, high molecular weight, anionic, AMPS copolymer (Nalco ASP-820) in straight and coiled tubing. The flow loop used consisted of three 1/2-in. OD coiled tubing reels with curvature ratios of 0.01, 0.019, and 0.031. A 1/2-in. OD, 10-ft straight section was also included to compare the drag reduction behavior between straight and coiled tubing. Various concentrations of drag reducing fluid were tested. The optimum concentration was then determined from the results of drag reduction exhibited by the fluid. The differential pressure versus flow rate data were reduced in terms of Fanning friction factor and solvent Reynolds number for estimating drag reduction characteristics.The results show that the drag reduction in coiled tubing are significantly lower than in straight tubing. As curvature ratio increases, the drag reduction decreases. A new drag reduction envelope (which is parallel to the Virk's envelope for drag reduction in straight pipes) is proposed to evaluate the essential characteristics of drag reduction in coiled tubing. The test data plotted on this new envelope clearly show the delayed onset of drag reduction and the effects of curvature and polymer concentration on drag reduction.Presently, the correlations for accurately predicting drag reduction characteristics of a commonly used drag reducing fluid in coiled tubing are non-existent. In this study, new drag reduction correlations are developed that can be used for the engineering design of coiled tubing hydraulics. The correlations are also evaluated using the experimental data from full-scale coiled tubing flow experiments and results showed the good agreement with the predictions from the developed correlations.     

Effect of drag reducer and pour point depressant on the wax deposition of crude oil pipeline

In this paper, the data of wax precipitation before and after the addition of the additives showed that the addition of the drag reducing agent (DRA) and the pour point depressant (PPD) cannot change the wax appearance temperature (WAT) of crude oil. When the dosage of DRA is small, the DRA cannot increase, stop, or slow down the precipitation of wax crystals. The addition of PPDs has no influence on the amount of precipitated wax crystals. From the GPC analysis, the molecular weight of the wax deposit samples in Linpu pipeline is from 500 to 76,800, which indicates that there is no enrichment of DRA in wax deposit samples. The results of IR show that the C?O group was not detected in the wax deposit sample of the Wei Jing pipeline, which indicates that there is no enrichment of the PPDs in wax deposit samples. The results showed that the DRA and PPD have no obvious effect on crude oil pipeline wax deposition.