| Thermal recovery of heavy oil is the main way of heavy oil development at home and abroad.At present,there are two kinds of commonly used heat treatment reservoir oil recovery technologies: heat injection fluid and in-situ burning reservoir.According to the characteristics of production technology,the steam injection method mainly includes steam huff and puff and steam flooding.However,the problems of wellhead lifting and channeling occur after steam injection in thermal recovery wells in various oil areas,which have a certain impact on the production and gathering of oil wells to a certain extent.Therefore,it is of great significance for the production and development of thermal recovery wells to investigate and analyze the problem of wellhead lifting and formulate measures to prevent wellhead lifting.Aiming at the problem of heavy oil pipeline wellhead lifting,this paper prevents pipeline leakage caused by wellhead lifting by compensating wellhead lifting.There are many kinds of compensators to compensate the wellhead lift by installing compensators on the wellhead pipeline.How to arrange compensators reasonably to obtain larger compensation is also the content of this paper.(1)Research on finite element method of heavy oil pipelineThe structure,stress and deformation of integral heavy oil wellhead pipeline and compensator are analyzed,and the stress state of heavy oil pipeline in actual operation is obtained.The finite element method of pipeline based on thermal coupling is used to analyze its temperature field,which provides the correct temperature load for the pipeline,and the contact non-linear calculation method is used to analyze the sealing performance of the compensator.A three-dimensional finite element model of heavy oil pipeline and compensator model is established by using the method of comparative analysis.(2)Integral force analysis of displacement piping system at wellhead of heavy oilThe space pipeline element is selected to discretize the displacement compensation pipeline system of heavy oil wellhead.The three-dimensional model of the whole pipeline system is established by using the pipeline unit,and the method of judging the maximum wellhead compensation is put forward,from which the maximum wellhead displacement lift is calculated.Finally,the temperature field and stress deformation of the compensation pipe system are simulated and analyzed.(3)Research on Pipeline Displacement Based on Rotary CompensatorIn order to simulate the rotating compensator truly and accurately,this paper simplifies the structure of the rotating compensator.The material nonlinearity and contact nonlinearity methods are used to simulate the axial compensator and the universal compensator separately by using solid elements.Then according to different working conditions,its strength is checked and its sealing performance is analyzed.At the same time,the advantages of universal compensator over axial compensator in space compensation are pointed out,and suggestions for improvement of universal compensator are put forward.(4)Influencing factors of displacement of surface piping system at wellhead of heavy oilOptimizing the layout of wellhead displacement pipeline system,establishing multi-criteria and multi-variable objective function.In order to maximize the compensation,various wellhead piping system design schemes are analyzed,including changing the length of straight pipe arm and rotary arm,and the height of fixed piping pier.Optimum design of pipeline is carried out to realize maximum compensation of wellhead lift. |
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