【作者】 王小兵；

【导师】 刘扬； 韩洪升；

【作者基本信息】 东北石油大学 ， 油气储运工程， 2010， 博士

【摘要】 粒子图像测速技术(particle image velocimetry,PIV)是一种全新的无扰、瞬态、全场速度测量方法。它不仅能够显示流体流场、流动的物理形态,而且能够提供瞬时全场流动的定量信息。螺旋流是湍流中的一种特殊的、规则的涡旋运动,是在石油工程实际中广泛存在的一种流动现象,如地面驱动螺杆泵井筒流体流动、水力旋流器中流体流动等都是螺旋流动。随着石油工程新技术的发展和推广,螺旋流在石油工程中的应用范围将进一步扩大。在地面驱动螺杆泵采油系统中,采出液由旋转的抽油杆与油管间的环空流到地面,部分螺杆泵的压头要用于克服流体在环空中做螺旋流动的摩阻。由于聚合物溶液的黏弹性,聚驱井中含聚采出液在环空中的螺旋运动更为复杂。水力旋流器是一种应用非常广泛的非均相混合物分离设备,其在石油工程中常被用来进行油水分离等。水力旋流器内部存在复杂的内、外螺旋运动,内、外螺旋流场的分布影响其分离效率。国内外学者已经对水力旋流器的结构和分离效率进行了大量的研究,但未对其内部螺旋全流场进行研究。聚合物驱油可以提高采收率,对保持油田稳产可起到十分重要的作用。但同时由于聚合物溶液复杂的黏弹性,也给采油工艺带来了新的问题,如抽油杆偏磨等现象。国内外学者采用了抽油杆加装扶正器等方法来解决偏磨问题。但以上方法均不能减小由于聚合物的黏弹性导致抽油杆所受的法向应力差。本文利用粒子图像测速系统研究了垂直管中不同介质螺旋流的流动规律、聚驱井地面驱动螺杆泵井筒中螺旋流动规律、水力旋流器内部螺旋全流场特征和螺旋流抑制聚驱井杆管偏磨的机理。研究结果标明,垂直管中的螺旋流与典型的轴向流明显不同,螺旋流的轴向速度分布不是典型轴向流的凸抛物线形,且随着聚合物溶液浓度的增大,其轴向速度分布曲线由凹形抛物线逐渐变化到中间凹的双峰抛物线,具有螺旋流断面流速分布的特殊规律。聚驱井地面驱动螺杆泵井筒中流体的轴向速度呈M形分布,不是典型的凸抛物线形,轴向速度有小的波动,轴向速度的大小随着抽油杆转速的增大而增大。随着抽油杆转速的增大,井筒中聚合物溶液的压力梯度有拐点,存在最小值。此抽油杆转速条件下,井筒中压头损失最小。水力旋流器旋流腔中流体切向速度呈中心对称的凹形抛物线分布,旋转动量主要集中在管壁和气柱附近。径向速度近似呈双M形分布,且气柱附近的径向速度大于管壁处。上锥段中不同介质的零轴向速度轴包络面(LZVV)是向左侧倾斜的近似圆锥面。下锥段中零轴向速度包络面不是圆锥面,而是向左侧倾斜的不规则圆柱面,右侧中间段有不规则向内突起。两个切向入射管中流体的流量影响着零轴向速度包络面的形状和分布位置。抽油杆与油管偏心环空间螺旋流的轴向速度分布不是典型的左右对称的凸抛物线形,而是有明显凹陷且左右不对称的抛物线,其轴向速度最大值点右移,偏向油管内壁,导致轴向速度梯度减小,其中窄间隙更为明显,因而能减小由于聚合物溶液的黏弹性所引起的偏心抽油杆法向应力差。螺旋流能抑制由于含聚采出液黏弹性造成的杆管偏磨现象,为解决聚驱井杆管偏磨提供了新的理论依据。更多还原

【Abstract】 Particle image velocimetry(PIV) is a new velocity measuring technique, transient and full field measurement with no interference. It can not only show such as fluid flow field, the physical form of the flow, but also provide quantitative information on the instantaneous flow field.As a special and regular vortex motion turbulent, spiral flow is widely applicated in petroleum engineering, such as the fluid flowj in a ground-driven screw pump well or in a Hydrocyclone.with the development of many new technologies in petroleum engineering, range of application of spiral flow would be broadened in this field.For a ground-driven screw pump production system, the produced fluid flows to the surface from the annulus between the rotating rod and tubing, and portion of pressure head, the screw pump supplied for, is losing to overcome the friction resistance along the annulus for produced fluid with spiral flow. It might be more complex for the spiral flow of the produced polymer in the annular in a polymer flooding well for the viscoelastic behavior of the polymer solution. Hydrocyclone, a kind of separation equipment for the non-homogeneous mixture, is widely used to separate oil-water mixture in petroleum engineering. Both inside and outside spiral flow are complex in a hydrocyclone,and distribution of the two kinds of spiral flow field do impact its separation efficiency .Though some domestic and foreign scholars have done a lot of research on the structure optimization and separation efficiency of the hydrocyclone, up-to-date the study on full flow field of spiral flow in a hydrocyclone is not found.Polymer flooding can enhance oil recovery, playing an important role in maintaining stable production of oil. However, as the complexity of the viscoelastic polymer solution, it has also brought new problems to the production technology, such as rod eccentric wear and so on. Some scholars deal with the problem by installing stabilizer rod or other methods, Yet none of mentioned methods can reduce the normal stress on the rod for the viscoelasticity of polymer solution.In this paper, the particle image velocimetry system is used, to study the law of spiral flow in the vertical pipe with different media, the law of fluid flow in the bore hole of surface driving screw pump with polymer flooding, the mechanism of spiral flow inhibitng the rod and tube eccentric wear in the polymer flooding wells, the characteristics of full flow field in a hydrocyclone. The results indicates,that the spiral flow in the vertical pipe is apparently different from typical axial flow, and the Axial velocity distribution of spiral flow is not a convex parabolic shape of the typical axial flow, moreover, with the increase of fluid viscosity, the trend of the radial velocity curve is gradually changed from a concave parabolic shape to a parabolic shape with two peaks and concave in the middle , which is the special velocity distribution law owned in a spiral flow section.The curve of axial velocity shows the M-type distribution in a bore hole of the surface driving screw pump symtem, not the typical convex parabolic one, and the axial velocity, with a little fluctuation, increases as the rod speed raises. With the rod speed increasing, the pressure gradient in the wellbore exists inflection point or a minimum value, thus the minimum wellbore pressure head loss is available at an optimum value of rod speed.Tangential velocity distribution in a hydrocyclone is a symmetrical concave parabolic distribution with the center of swirl chamber as the symmetry axis, and the spin momentum mainly accumulated near the wall of the hydrocyclone and air column. Radial velocity distribution approximlately shows a double“M”shape, and the radial velocity is larger near the air column than beside the wall of hydrocyclone. at the up part, the zero axial velocity envelope (LZVV) is a left-acclive similar circular conical surface in the condition of different media; at the lower part, the LZVV is no longer a circular conical surface, but a left-acclive irregular cylinder surface, with an irregular inward bulge in the right side at the middle segment.the shape and distribution location of the LZVV is affected by fluid influx from the two tangentialy incident tube.The axial velocity distribution of spiral flow between the rod and eccentric tube is not the typically dissymmetric convex paracurve, but a left-right asymmetry concave paracurve, the maxima of axial velocity shifts to the right and tends to tubing walls, leading the shear rate the rod to the fluid decreases and particularly prominent for the narrow gap, thus the normal stress of rod suffered also decreases owing to the viscoelasticity of polymer solution. Hence , the spiral flow can suppress eccentric wear of the rod and tube resulted from viscoelasticity of the production fluids, which offering a new theoretical foundation to solve eccentric wear of the rod and tube in a polymer flooding well.更多还原