Progressing Cavity Pump Rod String Mechanics Analysis And System Optimization Design For Directional Well

At present, most of domestic onshore oilfield has entered the later stage of development,so that the thin and poor reservoirs that have not been mined once upon, mining now. Due tothe geographical and environmental factors of reservoir, this portion of the new oil wellsmainly uses is in directional wells. Meanwhile, there are many advantages of progressingcavity pumps suitable for middle and latter stage production in the oil field, so that theprogressing cavity pump lifting needs to be applied in directional wells in the production.However, the design method of directional well progressing cavity pump system still uses thestraight wells, the pump depth just set near the deflection point, and the centralizerarrangement method still adopts the traditional uniform method. In fact, there are manydifferences in progressing cavity pump production system between in the directional wellsand the vertical ones. To establish the optimization design method that is suitable fordirectional well progressing cavity pump oil production system, in this paper, the passingcapacity analysis of progressing cavity pump in the directional well, rod string mechanicsanalysis, and optimal placement of the centralizer is researched.With the cubic spline interpolation to describe well track, the directional wellprogressing cavity pump rod string mechanical model is established, from the axial force,torque, bending moment of sucker rod string mechanics analysis and static strength andfatigue strength is checked respectively. Centralizer layout optimization method was putforward, according to the constraint from strength of rod, borehole trajectory and the size ofrod and tubing limit calculate the required centralizer number to realize rational distribution ofrod centralizer.Under the premise of without changing pump length, axial force are added to the pump,making the rod which include the pump bend. The beam element model and curved beamelement model are established and are calculated separately to get the allowable maximumvalue of pump setting depth. And then check the compressive bar stability, the intensity ofpump cylinder and the intensity of pump stator rubber in the process of progressing cavitypump through the deflecting section.The optimization calculation method which is suitable for directional well progressingcavity pump system is put forward, and the system optimization design model is established.Dividing the progressing cavity pump production system into five modules, and establishingthe parameters and equipment database of each module, the directional well progressingcavity pump optimization design software is compiled by using Visual C#language, realizingthe design or evaluation of directional well progressing cavity pump system. For wells thatare not put into production, according to the well parameters and the existing equipment, thewell design scheme which system efficiency is given by this software. For have been put intoproduction wells which average system efficiency is21.88%, by changing the speed,increasing the depth of the pump, change the progressing cavity pump and the complex adjustment to change the system condition respectively, system efficiency can be increased by33%. In this paper, the research provides reference for later oilfield exploitation, and providesa measure for designing of directional well progressing cavity pump system.