Directional Well Sucker Rod Pumping System To Optimize The Design And Numerical Simulation Studies

The sucker-rod pumping is in the lead of mechanical oil production in the world. In China, it is about 80% of oil production wells, it is 75% of overall oil production and the energy waste is more than one third of that of oil field. Recently, with the exploration deeply development and the drilling technology enhanced, the directional well is presented and widely used in a short time. The design and the management is much slower than the development velocity, what's more the optimization theory of the vertical well can't be used in the directional well for the directional friction. Therefore, this study has much important practical meaning.The sucker-rod pumping system is made up of the oil layer, the borehole and ground equipment. In order to keep this system worked efficiently, three subsystems must work in accordance. But the working environment of the directional well is much worse than that of the vertical well for the three -dimension variety of the well track. The dynamic behavior and the flexural deformation are much complicated. The directional friction of the rod string and the tubing would make the polished rod load and peak torque enhanced, or the rod is breakaway. With the variety of reservoir pressure, GOR and water cut, the sucker-rod system don't work in accordance. The low efficient wells need be redesigned to improve the system stability and make it work efficiently.In this paper, the nonlinear two-step partial differential equation is established to describe the dynamic behavior. To reach this, the stress and the curve in three-dimension space is basis. This model fully considers the effect from the dynamic character of the beam unit, the sucker rod and the pump. Combined with the accordance between oil layer and the pumping and based on the numerical stimulation technology, this paper is centered on optimization design and improving the system stability. The main research content is as following.Based on the geometry character of beam unit, the kinematics model is established. So the velocity of point of suspension, the displacement, the acceleration and the torque are available. Combined with optimization theory, the objective function of balance adjustment is established.On basis of strained condition of the rod string in three-dimension space, the load analysis of the rod string is studied and the two-dimension and three-dimension node load model is established. It offers the theory basis for combined rod design, the analysis of directional friction from the tubing and the rod and that of the rod breakaway.Based on the oil production and pumping-setting depth, the objective function of optimization design is EL It fully considers the accordance between the oil layer and the production system and the dynamic character of the pumping unit, the rod string and the pump. The numerical stimulation technology is used. Therefore, the ideal working state is available.By unit stress analyses of the sucker rod, base on the study the extensional vibration differential equation, it establish the three-dimensional forecast mathematical model whichtake the coupled vibration of the sucker rod, tube, fluid column in tube in consideration. Adopting the finite difference approach, it come up with compound difference solution method, which combine the grade step implicit difference in the same rod and change step explicit difference at rod connect point ,the compounded difference method can solute the vibration differential equation quickly in system simulation, the viscous damping coefficient not only take the friction between the rod and fluid but also the friction between the fluid and collar, fluid and centralizer, to accurately solute the model , the viscous damping coefficient change with the well depth, which perfect the sucker rod dynamic mathematical model and the numerical solution, improve the practicability and precision of system simulation.Through in-depth stress analyses of sucker rod in three-dimensional well bore, it come up with the design method of the sucker rod in directional well. By research the flexural deformation of the sucker rod, based on the theory of beam bending, it establish the mathematical model for rational distribution design of sucker rod centralizer, which can prevent the eccentrically abrasion of rod -tube.Based on the production difficulty of deep oil pumping and the geometric structure and principle of deep well loosing-load device, it establishes the mathematical model for loosing load, which supply the technical base of deep oil pumping design.Aiming at eccentrically abrasion of rod-tube, tube-casing, the theses in-depth study the mechanism and anti-eccentrical abrasion. The matching down hole tool, ratable production wellhead, sucker rod centralizer, ratable tube centralizer can validity prevent the eccentrical abrasion and prolong the pump inspection cycle.In a word, through the in-depth research, it not only perfect the mathematic model of sucker rod in directional well but also combine the optimum design with numerical simulation of dynamical character of sucker rod , oil pump ,beam unit based on the system theory, the theses in-depth study measure which improve the stability of system, which contribute to advance design and management level. In windows, adopting object-oriented programming technology, the optimum design and simulation software for the rod pumping system of directional well have been developed which base on the oil flied net database in VB. The software supply the tool for scene engineer, which have been successfully applied in Zhongyuan Huqing oilfield ,it bring favorable economy and social benefit have been got.