Downhole String Mechanics Analysis And Optimization Design

This paper mainly develops the mechanics research and optimization design about tubing string and packer, after collecting and analyzing the data on mechanics analyzing and calculating tubing string in the down hole. The paper establishes mechanics analyzing mostly models on uniform, combination tubing or uniform, combination tubing with one packer and uniform, combination tubing with dual packers. It manly analyzes four kinds transmutations of piston effect,temperature effect,expansion effect,helical buckling effect in the system of tubing and packer. At the same time, the research and application of temperature and pressure field have been developed based upon the characteristic of local technology, calculated stress, displacement and temperature at different place under different temperature and pressure. The paper offers methods ensure that the system of tubing-packer works well balanced, and optimizes tubing structure, improves success ratio of working in the down hole. The paper considers production situation of oil field in zanaruer, kazakstan, it is also mainly research parts of two helping items that one is tubing string designing in zanaruer oil & gas field abroad, one is for acidizing fracturing and injection tubing string designing in China. The item aims at forming a set of evaluating system about mechanics analyzing and safety intensity calculating for tubing string-packer accord with local situation. It mainly developed several aspects as following:1) Collecting, researching and analyzing the sutra literature and application data on mechanics analyzing and calculating tubing string in the down hole, having put up with scheme according to oil field needs;2) This paper is an extension of papers by Lubinski et al.Woods and Hammerlindle. Based complex tubing string mechanics analysis and deduced formula, presents methods that can solve some question at local.3) Established temperature field calculating model based un-steady heat exchange according to tubing string technology in the high temperature and pressure super hole.Established pressure field calculating model based on hydrodynamics to calculate friction resistance.4) At present, it is important that how to choose suitable tubing for tubing-packer system in oil field which contains highly H2S(sulfured hydrogen ),CO₂ (carbon dioxide)erosion matter.This paper presents a method for solving problem that how to calculate tubing intensity in zanaruer oil field, kazakstan.5) Based on well depth, temperature, pressure and erosion medium in zanaruer oil field, kazakstan. To choose suitable model and size of tubing.6) Using methods by working over tubing mechanics analysis designing tubing string structure of production or task in zanaruer oil field, kazakstan.This paper presents some methods that be used to calculate stress and distortion by researching and deducing for fracturing, acidizing and injection technology . For the first time, taken tubing -packer as a whole system, in allusion to special requirement oil field, chose and designed firstly optimum completion tubing, then estimated intensity and security of completion tubing. After oil & gas well production, can easy to carry out mechanics analysis for tubing string as well as optimizing reconstructing technology scheme. Have developed temperature field and pressure field research, and realize calculation temperature and pressure value at random place of tubing string full of different liquid so that can calculate the effect of changes in temperature or pressure on tubing under the complex work situation. Have completed dual packers analysis in force, an nd changes in force if the packer permits no tubing movement. Have deduce strictly force in pistoneffect and helical buckling effect, corrected several calculation methods for literature so as to be close to the fact in oil field. In the end, after compared calculation with local data, it is proved that analysis on tubing is reasonable and correct.