The Research Of The Viscoelastic Fluid Flow In The Technology Of Polymer-flooding Wells

In recent years, the technology of polymer-flooding wells as an important pillor for increasing the yeild in daqing oil filed, has increased oil recovery by more than 12% on the basis of water-flooding. While gaining the huge enormous benefits, there are two urgent problems as the follows which must be resolved in the technology of polymer-flooding wells. First, the eccentric wear of the sucker rods aggravates, and the probability of rod broken and wells opeating increases. Second, the vibrating of polymer injection pipelines aggravates, the period of examining pumps and the life span of the sucker rods shortens, and pump efficiency declines. Adopting common conversion Oldroyd-Maxwell constitutive equation in this paper, the flow equation of the unsteady flow of viscoelastic fluid in the eccentric annulus and polymer injection pipelines was established, the initial conditions and boundary conditions were given, and the flow field and stress field of vescoelastic were obtained by numerical solution. By studying polymer solution in eccentric annulus and polymer injection pipeline in the viscoelastic flow pattern obtained: in the eccentric annulus, the greater eccentricity, the greater asymmetry in the flow filed and the normal force, a joint force of the normal force—radial force also increased. The easier it is to have an eccentric wear.At the same time, the main reason for the polymer injection pipelines vibrating is also the normal force. According to the above theory, measures of centralizing the sucker rods in to prevent eccentric wear have been applied in polymer-flooding wells and significantly reduced the eccentric wear. Proposing the transformation of three-round rectangular structure for the ground pipeline, this provided a theroetical and practical basis for the preventing and rectificating of pipeline vibration, and achieved substantial economic benefits.