CO2泡沫压裂液的流变性及井筒摩阻计算方法研究

进行了CO2泡沫压裂液的室内配制、流变性测定以及摩阻计算方法研究。室内实验中观测了CO2泡沫压裂液的形成、动态变化、泡沫结构,测定了CO2泡沫压裂液的流变性,发现其属于假塑性非牛顿流体。推导了CO2泡沫压裂液在油管内流动的摩阻计算公式,计算了不同管径、不同排量、不同泡沫质量时的摩阻曲线,进行了井筒内CO2泡沫压裂液摩阻压降实测,与计算方法相比误差在工程应用允许范围内。该研究所得到的CO2泡沫压裂液流动特性、摩阻压降计算方法、经验图版等,可供工程应用中参考。     

基于Cerberus的连续油管作业摩阻分析

连续油管作业由于其具有不可替代的优势,现在越来越多的被用于各种油井作业中,但由于管径较小,摩阻压降较大,存在一些局限性,Cerberus是连续油管的模拟软件,能对作业过程进行模拟分析和计算。本文基于Cerberus对连续油管作业摩阻进行了分析。     

周期惯性力影响下矩形通道泡状流阻力特性

泡状流广泛存在于各种化工反应设备中,研究周期惯性力影响下矩形通道泡状流的阻力特性,可以为研究非稳态条件下的流动特性提供实验支持。本实验在常温常压条件下进行,摇摆工况选定为5°-8 s、10°-8 s、15°-8 s、15°-12 s和15°-16 s,实验结果表明摇摆条件下瞬态摩擦压降的变化具有明显的周期性,两相平均阻力系数是稳态摩阻系数的几倍到十几倍,随着两相Reynolds数的变大,瞬态摩阻系数的波动幅度和平均水平均变小;摇摆周期越小,摇摆振幅越大,即摇摆运动越剧烈,摩擦压降的波动幅度也越大;定义了周期惯性力的影响系数(摇摆条件与竖直条件下摩阻系数的比值),利用量纲分析和多元拟合方式得到关于影响系数的经验关系式,预测值与实验值符合程度较好。     

气液两相流在卧式螺旋管内摩阻特性实验研究与计算模型的建立

为了研究气液两相流在卧式螺旋管内的摩阻特性及其影响因素,得到一个适用范围大、准确性更高的摩阻计算公式。采用室内实验的方式,测量出不同压力、流量、干度条件下气液两相流在螺旋管内摩阻压降,幵采用两相摩擦乘子ф2LO来处理实验数据,描述不同条件下的摩阻压降。实验结果表明质量流量对螺旋管内摩阻的影响较小,螺旋管内摩阻随着压力的增大而减小,在干度小于0.35时,螺旋管内摩阻随着干度的增大而增大,当干度大于0.35时,螺旋管内摩阻随干度增大而变化不大。幵且通过量纲分析以及线性回归的方法推导出气液两相流在螺旋管内的摩阻计算公式,幵与实验数据进行对比分析,拟合效果较好。     

气液螺旋环状流压降特性研究

考虑旋流衰减的影响，对气液螺旋环状流的压降特性进行研究并推导出了螺旋环状流压降预测模型。定义压降旋-直比系数为气液两相螺旋环状流和气液两相直流的压降之比，以此来表征旋流衰减对压降的影响。基于量纲分析的方法对压降旋-直比系数进行分析，推导出其表达式，压降旋-直比系数依赖于Lockhart-Martinelli 参数和气相Froude数变化。最终，得出了气液两相螺旋环状流的压降预测模型。在50 mm内径的水平管内对螺旋环状流的压降特性进行了实验研究，其中气相表观流速变化范围为10~16 m/s，体积含液率（LVF）变化范围为0.6%~4.8%。通过与实验数据进行对比，压降预测模型的相对误差在±15%以内，为工程应用提供了参考。     

管道表面润湿性对层流流动阻力的影响

基于建立的小型循环管路实验平台,实验研究了自来水、乙二醇和26#白油分别在304不锈钢管、有机玻璃管、聚丙烯管(PP管)和聚四氟乙烯管(PTFE管)内层流流动的阻力特性。通过测量不同流量下的压降,计算得到了摩阻系数和泊肃叶数随雷诺数的变化关系以及相同雷诺数下摩阻系数随接触角的变化关系,同时采用接触角测定仪分别测量了3种液体在4种管道表面的接触角,讨论了管道表面润湿性对流动阻力的影响规律。实验结果均表明,管道表面润湿性对流动阻力产生了一定的影响:在相同雷诺数下,随着液体在管道表面接触角的增大,液体的泊肃叶数和摩阻系数均呈现减小的趋势;疏液管道表面润湿性对摩阻系数的影响大于亲液管道,并且在雷诺数较小时这种现象表现得更加明显。     

螺旋折流板换热器阻力及换热性能数值模拟

为研究连续螺旋折流板换热器阻力及换热性能,采用CFD数值模拟方法,选用k-ε湍流模型,比较了螺旋折流板换热器壳程流动与换热性能,进一步研究了不同螺旋角在不同入口速度下的阻力及换热性能。结果表明:不同螺旋角的螺旋折流板换热器,随着螺旋角增大,进出口压降逐渐减小,换热系数也减小;比较螺旋折流板换热器的单位压降换热系数,为了保证换热效率,螺旋角为40°时换热器的综合性能最优。计算结果为螺旋折流板换热器的螺旋角选择提供了理论依据。     

三维肋翅片管在螺旋折流板换热器中的应用研究

本文研究了三维肋翅片管在螺旋折流板换热器中应用的传热与压降性能,以水和VG32液压油为换热对象进行实验,并与弓形折流板光滑管换热器进行对比.在相同的Re下, 螺旋折流板三维肋翅片管换热器的Nu足弓形折流板光滑管换热器的5.03~5.96倍.在相同流量下,螺旋折流板三维肋翅片管换热器壳程压降稍大,但它的传热流阻性能比足弓形折流板光滑管换热器的2.78~3.66倍.实验结果表明:三维肋翅片管枉螺旋折流板换热器中应用具有最佳的传热流阻综合性能.     

螺旋折流板三维肋翅片管换热器的传热性能研究

文章以水和VG32液压油为实验换热对象,研究了其在螺旋折流板低翅片管换热器和螺旋折流板三维肋翅片管换热器壳程的传热与压降性能。在相同的Re下,螺旋折流板三维肋翅片管换热器的Nu是螺旋折流板低翅片管换热器的1.6～2.6倍。在相同流量下,螺旋折流板三维肋翅片管换热器壳程压降稍大,但它的传热流阻性能比是螺旋折流板低翅片管换热器的1.39～2.15倍。实验结果表明:螺旋折流板三维肋翅片管换热器具有最佳的传热、压降和换热量综合性能。文章还对螺旋折流板三维肋翅片管换热器的强化传热的机理进行了分析。     

高粘度流体在机械搅拌槽中的传热

研究了高粘度牛顿流体和非牛顿流体在螺杆-导流筒、螺杆-导流筒-直管组两种搅拌体系中的传热行为。结果表明,设置导流筒和直管组后,对夹套侧的传热膜系数α_j没有明显影响,导流筒侧和直管组直管外侧的传热膜系数α_d和α_c都较α_j大,传热面积比夹套增加一倍左右,从而增强了搅拌槽的传热能力。在所有几何因素中,搅拌桨径 d和导流筒内径 D_(ti)对传热膜系数影响最大。搅拌桨的转向对传热无明显影响。分析了传热关联式中 Re的方次的变化情况。用因次分析和回归分析得到的夹套、导流筒和直管组传热面的传热关联式和文献结果吻合甚好。     

Power Law Fluids in a Circular Curved Tube. Part III. Numerical Simulation of Laminar Flow

The equations of motion and continuity of a fully developed, steady-state, isothermal, incompressible laminar flow of power law fluids within a toroidal-type coiled tube geometry have been solved numerically using the successive overrelaxation method. Numerical solutions have been obtained for curvature ratios from 5 to 100, Dean number from 1 to 300, and power law index from 0.5 to 1.5. Dean's constraint has been relaxed and the numerical solutions for primary and secondary flow, and the numerical results of the friction factor for different values of Dean number, curvature ratio, and power law index have been computed. The solutions have been carefully checked for accuracy and the results are compared with previous studies. The numerical results are found to be consistent with the published results for the case of Newtonian fluids. The ratio of friction factor of a curved tube to a straight tube increases with the Dean number and also with the power law index.     

FULLY DEVELOPED LAMINAR FLOW IN A HELICALLY COILED TUBE OF FINITE PITCH

Solutions for steady, fully developed, laminar flow of an incompressible Newtonian fluid through a helically coiled tube of finite pitch were obtained by finite difference calculations. Prior theoretical solutions have apparently been limited to toroidal flow (with zero pitch). The computed results are consistent with those for this limiting case and with prior experimental data for finite pitch. The behavior for helical coils is intermediate between that for a straight pipe and a torus, and, for a moderate degree of pitch differs only slightly from that for a torus. A correlating equation was developed for the friction factor for all Reynolds numbers, all ratios of coil radius to lube radius and all ratios of pitch to coil radius for which the flow remains laminar.     

Interfacial stress in non-Newtonian flow through packed bed

This study investigates the pressure drop characteristics, shear stress in packed bed with shear thinning power law type non-Newtonian liquid. A mechanistic model has also been developed to analyze the pressure drop and interfacial stress in packed bed with non-Newtonian liquid by considering the loss of energy due to wettability. The Ergun's and Foscolo's equations were used for comparison with the experimental data. The Ergun equation was modified to account for the effect of flow behavior index of non-Newtonian fluid in the column. The intensity factor of shear stress and the friction factor were analyzed based on energy loss due to wettability effect of liquid on the solid surface.     

连续油管压裂技术在辽河外围低渗油藏的应用

连续油管水力喷射压裂是解决纵向多层压裂难题的有效手段。通过对连续油管水力喷射环空压裂技术的原理、工艺流程、摩阻、优缺点评价等方面进行分析,认为这种环空加砂压裂通过连续油管内喷砂射孔与环空加砂相结合的方式拓展了连续油管的应用深度,提高了连续油管的利用率,降低了对水力喷射喷嘴寿命的要求,提高了连续油管压裂的排量限制,从而使连续油管具有更高的现场适用性。辽河油田采用国内自主连续油管设备、井下工具,自主设计、组织实施了一次连续油管水力喷射环空加砂分段压裂,取得了良好的效果,获得了大量的宝贵经验。     

Investigations of heat transfer and pressure drop between parallel channels with pseudoplastic and dilatant fluids

Central to the problem of heat exchangers design is the prediction of pressure drop and heat transfer in the noncircular exchanger duct passages such as parallel channels. Numerical solutions for laminar fully developed flow are presented for the pressure drop (friction factor times Reynolds number) and heat transfer (Nusselt numbers) with thermal boundary conditions [constant heat flux (CHF) and constant wall temperature (CWT) ] for a pseudoplastic and dilatant non‐Newtonian fluid flowing between infinite parallel channels. A shear rate parameter could be used for the prediction of the shear rate range for a specified set of operating conditions that has Newtonian behavior at low shear rates, power law behavior at high shear rates, and a transition region in between. Numerical results of the Nusselt number [constant heat flux (CHF) and constant wall temperature (CWT) ] and the product of the friction factor and Reynolds number for the Newtonian region were compared with the literature values showing agreement within 0.36% in the Newtonian region. For pseudoplastic and dilatant non‐Newtonian fluids, the modified power law model is recommended to use because the fluid properties have big discrepancies between the power law model and the actual values in low and medium range of shear rates. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3601–3608, 2003     

Laminar mixing of shear thinning fluids in a SMX static mixer

Flow and mixing of power-law fluids in a standard SMX static mixer were simulated using computational fluid dynamics (CFD). Results showed that shear thinning reduces the ratio of pressure drop in the static mixer to pressure drop in empty tube as compared to Newtonian fluids. The correlations for pressure drop and friction factor were obtained at Re_MR?100. The friction factor is a function of both Reynolds number and power-law index. A proper apparent strain rate, area-weighted average strain rate on the solid surface in mixing section, was proposed to calculate pressure drop for a non-Newtonian fluid. Particle tracking showed that shear thinning fluids exhibit better mixing quality, lower pressure drop and higher mixing efficiency as compared to a Newtonian fluid in the SMX static mixer.     

The flow of non-Newtonian solutions through packed beds

The rheological behavior of aqueous solutions of Separan AP-30®, polymethylcellulose, and polyvinylpyrrolidone was studied experimentally. These solutions exhibit non-Newtonian flow behavior in simple shear, and are characterized by one of several 2, 3, or 4 parameter rheological equations. The equations used included the power law, the Ellis model, Spriggs equation, the Herschel-Bulkley equation, and Meter's model. The power law model fits the data for each of the solutions over a limited range of shear rates, whereas the other models, which include either a lower shear rate limiting Newtonian viscosity, and/or an upper shear rate limiting Newtonian viscosity, or a yield stress, fit the data well over a wide range of shear rates from 0.00675 to 1076 sec^?1. The pressure drop-flow rate data for the same aqueous solutions flowing through packed beds were correlated well by the Ergun equation using the various rheological models applied in this work to evaluate a modified fluid viscosity. In each case it was found that the rheological model which best fit the viscometric data also gave the best packed bed friction factor correlation, and that no one model, such as the powerlaw, or the Ellis model, is the best one to use in all cases for all solutions. For polyvinylpyrrolidone solutions large deviations between experimental values of friction factor and those from the Ergun equation occurred for modified Reynolds numbers greater than one. A pseudo viscoelastic parameter was used to improve the friction factor correlation empirically at high Reynolds numbers.     

Anisotropic convective heat transfer in microlattice materials

Fluid dynamics and heat transfer of flow through periodic open‐cellular microlattice structures are characterized for varying superficial flow orientations and flow rates to investigate heat transfer and pressure loss anisotropy. For given Reynolds number, friction factor is lowest when flow is aligned with the largest straight‐through passages in the microlattice. A maximum friction factor, over twice the optimally aligned friction factor, exists for flow orientations between π/8 and π/4 rad off the optimal alignment, with little variation in friction factor for π/8 and π/4 rad. Heat transfer is maximized at π/4 rad off axis from the largest straight‐through passages; however, less angular variation occurs in Nusselt number than in friction factor. Empirical correlations involving superellipses yield analytical equations describing Nusselt number dependence on flow angle and Reynolds number. This work enables selection of optimal flow orientations and optimal cellular architecture in convective heat transfer implementations of microlattice materials for lightweight and multifunctional applications. © 2012 American Institute of Chemical Engineers AIChE J, 59: 622–629, 2013     

Mixed convection flow of non‐Newtonian fluid from a slotted vertical surface with uniform surface heat flux

In the present paper, the combined convection flow of an Ostwald–de Waele type power‐law non‐Newtonian fluid past a vertical slotted surface has been investigated numerically. The boundary condition of uniform surface heat flux is considered. The equations governing the flow and the heat transfer are reduced to local non‐similarity form. The transformed boundary layer equations are solved numerically using implicit finite difference method. Solutions for the heat transfer rate obtained for the rigid surface compare well with those documented in the published literature. From the present analysis, it is observed that, an increase in χ leads to increase in skin friction as well as reduction in heat transfer at the surface. As the power‐law index n increases, the friction factor as well as heat transfer increase.     

连续油管速度管柱技术的应用

重点介绍了连续油管速度管柱技术在实际中的应用,讨论了在行业应用中的注意事项。随着大庆油田不断的开发,许多自喷井和气井的产量变小,最终完全停止生产,而恢复井产量的一个方法是积液回到自喷的流体中去,安装一个直径较小的连续油管（速度管柱）。很多参数（当前和将来地层的压力,流体和天然气产出率,连续油管的直径和深度,井口,井底流压等）影响速度管柱的性能。通过评价速度管柱的设计是否能将积液井重新变成自喷井和自喷持续的时间,地层流入井内的流体性能和流出连续油管的液体性能,推广其运用,从而提高油气的产量。