Theoretical And Experimental Studies On Oil Production By Down Hole Self-excited Vibration Method

In order to generate down hole vibration, not only reduce wave energy attenuation , butalso long term process the oil reservoir so that improve the treating capacity, down holeself-excited vibration equipment is developed. The technique of down hole self-excitedvibration , using the oil tubing string cyclical elastic deformation to produce self-excitedpressure wave in the wellbore, transforms elastic energy of the system into the wave energyby vibrator, and stimulates oil layer with the low-frequency acoustic wave. As a result,formation plugging near the wellbore is removed, and the productivity of wells increasesbecause of the improved flowability of crude oil.In the paper, factors of the reservoir damages and the main measures for removing plugwere analyzed. Through the analysis to stress of tubing string for conventional sucker rodpumping system, the tubing string longitudinal vibration mathematical model wasestablished, motion equation was deduced, and basic structure of vibrator was preliminarilydesigned for laboratory experiment. Based on the simulating lab tests, the relationshipbetween wave parameters that are pressure amplitude and surge frequency and the influencefactors such as vibration plate submergence depth, platter diameter, spacing, vortex grooveand so on was proceeded, and the key parameters to optimize vibration device were foundout. At the same time, lateral propagation behaviors in the reservoir and verticaltransmission rules in the wellbore were tested, laying a foundation for predicting the depthof vibration wave plugging removal and determining appropriate installation position ofvibrator. More over, according to the experiment results, optimization design was made onthe parameters of down-hole vibration device, and the stimulation mechanism of vibratoryproduction was discussed. The application of the technique by 11 wells in Gudao oil field indicated that technical effective rate was 91%, the average producing fluid level heightenedby 106.6 m, daily fluid production rate increased by 16.4 t, pump efficiency raised 24.5%,and the period of validity was more than one year. It is an efficient new technology withlow-cost, non-polluting, long valid term for plug removal and enhanced production wellstimulation in fields during the high water-bearing interval, and has good applicationprospection.