Study On Mechanical Theory,analysis Method And Application Of Fine Layered Injection And Production Pipe String

Most of China's oil fields have entered the middle and late mining.Because the remaining oil is mostly distributed in the thin layer,Strengthen the exploitation of the thin layer is the key to the sustainable development of the oil field.Fine layered water injection and oil production are the important means to exploit thin layers of oil and gas resources.The pipe string and technological process are becoming more and more complex.Compared to the previous column,fine layered injection and production pipe column face injection pressure is high,the packer's displacement demand precise control,existing pipe strings mechanics theory,analysis method is difficult to meet the computing needs of the actual production.Therefore,it is necessary to depth analyse fine layered injection and production column's characteristics,to establish the mechanical model and analysis method which is appropriate to fine layered injection and production pipe column.Based on the theory of fluid mechanics,elastic mechanics and differential geometry,the basic equations of flow field,temperature field and force field are derived.Describe the geometry of given 3D curved well trajectory,with the cubic spline interpolation method,the piecewise functions of well deflection and azimuth angle over sounding are provided.The tubular column's calculating formula in the global coordinate is given.Establish the pressure equations of the pipe's flow field and annular flow field,and deduce the calculation formula of the force from the flow field.The calculation equation of temperature field is established,and the calculation formula of the temperature stress is given.Based on the space straight beam theory and analysis of the pipe column element's forces,the column element's equilibrium equations,geometric equations and constitutive equations were given.Several basic assumptions about mutual action between the pipe string and well wall were set up,pipe string's buckling nonlinear differential equation is established.By Galerkin method and nonlinear scale method,the conFig.urations of the pipe's sinusoidal buckling and spiral buckling state were obtained,and these results are used to calculate the pipe's sinusoidal buckling and helical buckling critical load.Analysed the impact of the reaction force from wellbore on the pipe string's axial force and torque,two assumptions were set up,one is about the reaction force from wellbore,and the other is about the pipe string's curvature torsion,combined with post buckling critical load calculation formula and buckling analysis of the mathematical model,the pipe string's axial force-torque calculation model is estabilshed.The types and structures of common multi-packer pipe string are studied,and the influence of downhole tools on the pressure field,annulus flow field,temperature field,axial force,torque and displacement are analyzed.A method for mechanical analysis of multi-packer pipe string is put forward.The packer's rubber friction,temperature effect,ballooning effect and axial force's coupling method is put forward.Because of the stress analysis,need to know the anchoring force of packer anchor,to Y341-114 sealing packer,for example,to carry out sealing packer rubber's friction test under different pressure,the value of the friction force between the packer rubber and casing under different pressure is given;to SLM-114 hydraulic anchor fluke,for example,to carry out the fluke's anchor concentration test under different pressure,the anchor force value under different pressure is given.Based on the theory of pipe string mechanics,The buckling behavior of pipe was tested on the tube mechanical test rig.The test results are compared with the theoretical analysis results,the maximum relative error is 4.9%,so the correctness of the theory is verified.Design the tubular mechanics software's three modules: data input and output module,database module,calculation module.Design the function of these modules.The multi-packer pipe string's analysis software is programmed.For the layered water injection pipe string,separate layer production pipe string,the mechanical analysis software of fine layered injection and production pipe string is applied to practical application.The error is within the engineering acceptable range.