Water Craft Column Mechanical Behavior Study

During the oil exploration and development, the water injection packer tubing string is broadly applied on well test, water injection and production etc. And it is the mainly loads bearing and power passing component of downhole operation and production. During the downhole operation and production, the tubing string has three balance states under the action of the internal pressure, external pressure, axial force, torsion moment, force moment, anti-force of the well wall, viscous force and coulomb friction. The three balance states are stabilization-state, sine-state and spiral-state. During the downhole operation of the high temperature, high pressure well and the great displacement well, as the change of the pressure of the internal liquid and the external liquid, the temperature and the force, the tubing string are the different states or it changes during the different states, which lead to great axial distortion of the tubing string (it can make sealing spile emerge from the sealing canister or the sealing thread surge which lead to miss out seal and leak to seal), great bend stress(it can make the tubing string fracture or permanent spiral bend) and great anti-force and friction between the tubing string and the wall of well( it can make the tubing string self-lock). All these will lead to downhole operation accident and wasting much money. The main reason of the downhole operation accident is that people do not understand the mechanics action of the tubing string that is in different state. During designing the tubing string and choosing the construction parameter, people don't consider the change of the force, the stress and the distortion during the downhole operation. So the study of the stability, the shape after flections, the friction, the loads passing, the stress, the distortion of the tubing and other mechanics actions of the string in different well is an urgent and pivotal question to the exploration, development and the production technic development of the oil and gas field. This text synthetically considers the affection of the friction, the internal and external pressure, the viscous force, the deviation angle and the well bore bend to the water injection packer tubing string. On the base of these, a mechanics module and distortion differential equation about the water injection packer tubing string in the three-dimensional bend wallbore is constructed. In this text, a mechanics module and distortion differential equation about the water injection packer tubing string under different work condition is constructed. By quoting the water hammer idea about the pumping system and the fracturing pump, this text also constructs a coupling module about the tubing string and the liquid during the downhole operation and a throttle differential pressure mechanics module when the section of downhole tools change. By combing the simulate computing of the computer with the production fact, this text studies the mechanics action of the water injection packer tubing string. It provides scientific theory reason and analytic measure for the design of the combination about the tubing sting and the choice of the construction parameter. And it also provides the theory reason for analyzing the work capability of existing downhole tools anddesigning the new style downhole tools. The paper's main contents come from the science research named the Water Injection Technics Tubing String and Water Injection Technics software design that are developed by South West Petroleum Institute and JiangHan Oil Withdrawal Technology Research Institute that is a sub company of China Petrochemical Corporation in JiangHan oil field. The detail research works are as follows:1, On the basis of collecting the study actuality at home and abroad, analyze the water injection technics tubing string and water injection technics' existing development and the exiting problem in using process and bring forward the concrete research project about the study of the mechanics action of the water injection technics tubing string combined with the water injection technics tubing string research practice of JiangHan Oil Withdrawal Technology Research Institute;2> analyses the structure and the working mechanism of the downhole tools of the water injection packer tubing string and the water injection packer tubing string;3 -. On the basis of the geometry description about the three-dimensional bend wallbore and analyzing the geometry distortion relation and the force of the water injection packer tubing string that is in three-dimensional bend wallbore and according to balance equation and physics equation, construct the mechanics module and distortion differential equation of the water injection packer tubing string that is in three-dimensional bend wallbore;4, On the basis of the energy analyses of the three-dimensional bend wallbore tubing string, according to the minimum potential energy theory and the variation theory and making use of the gradational analyses method, gain the sine-state and spiral-state solution of the distortion differential equation and confirm the critical loads of the sine-state and spiral-state;5> According to the solution of the sine-state and spiral-state, analyze the distribution of the stress, axial force and force moment, the change of the temperature, the action of the internal and the external pressure, the action of the axial force and the axial distortion (the sine-state and spiral-state solution) and provide the borderline condition and continuity condition.6n Construct the mathematics and mechanics module of the water injection packer tubing string under different work condition that the change of the liquid pressure and temperature affects the force and the distortion of the tubing string.7, Construct the water hammer coupling module about the tubing string and the liquid during the downhole operation and the throttle differential pressure mechanics module when the section of downhole tools change.8> By making use of the Visual Basic and developing the water injection technics tubing string and water injection technics software, compute and check the force and the distortion of the water injection packer tubing string under different work condition.