Research Of Tubelkess Hollow Sucker Rod's Mechanical Behvior And Wellhed Supporthing Technlogy

With the recovery of the oil field gradually, many problems appeared, such as the risingwater content of oil and the eccentric wear between sucker rod and tubing. These problemsworsen the conditions, increase the duration of operation, raise the installation investment.According to these problems, tubeless hollow sucker rod pumping technology is studied.Since the bottleneck lies in the drag force while the well fluid flowing up the hollow suckerrod, which is unfavorable to rod fall. On this basis, a new hollow sucker rod pumping schemewith hydraulic feedback function is developed. Comparison of four kinds of pump leads toconclusion that this new pump can eliminate the hollow sucker rod float problem, whicheffectively contributes to system efficiency improvement and extended production period.The main content is in the following below:(1) Comparison of conventional sucker rod pump, top big-bottom small type ofhydraulic feedback pump, top small -bottom big type of hydraulic feedback pump, and newtype of hydraulic feedback pump leads to conclusion that the hydraulic feedback force of thenew type of hydraulic feedback pump in the same diameter of pump which can eliminate thehollow sucker rod float problem. Design the plan of the hydraulic feedback pump, andintroduce the detail of the operating principle. The wellhead equipment is modified to fit thehollow sucker rod pumping system. Finally the mechanical analysis and calculation of thehollow sucker rod leads to the calculation of the various load during upstroke anddownstroke.(2) Performance prediction is conducted on the hydraulic feedback type hollow suckerrod string by integrating the effect of fluid flow and hollow rod dynamics. The predictivemodel of the hollow rod and the fluid with the initial, upper boundary and lower boundarycondition is established for it. And the boundary condition is divided into loading, absorbing,unloading, flowing of four stages which are analyzed. (3) A kinematic model is developed for the mechanism of beam pumping unit, thedisplacement, velocity, acceleration in the hanging-point and the corresponding curves in amotion period are obtained. The implicit difference method of the initial, upper boundarylower boundary condition and partial differential equation is used. Using the chase-aftermethod to slove the equation, and simulated by computer program to simulate the relationshipbetween load and displacement in arbitrary section of hollow sucker rod at any moment. Thegraghic results is compared and analysised.(4) The total size and components of hollow sucker rod pump inherent with hydraulicfeedback mechanism is designed on the basis of the national standards, including the selectionof tubing, the calculation of the pump's maximum diameter and length, sucker rodspecification and the matching of the pump's diameter.(5) The operation of software emulating the hydraulic feedback type hollow sucker rodpumping system is introduced and both the basic function and using method of the software isalso presented.