The Simulation Of Gas-Liquid Two-Phase Flow Patterns In Vertical Pipe And The Study On Safety Evaluation Of Bubble Breaker

Continuous gas-lift oil production is an important oil extraction technology; it has following features, such as it can be used in variety fields, has a long term of mean time between failures, simplifies the operation procedure and reduces the amount of operation personnel. With the development of the western oil field and the ocean oil field, once again, this technology begins to draw the attention of the people. In terms of the energy utilization efficiency, the gas-lift method has a low efficiency. The investigation result shows that the installation of bubble breaker in the gas-lift well will affect the gas-lift efficiency, it also can transform the slug flow and transition flow to bubble flow, according to this way, the gas-lift oil production efficiency can be greatly improved. Whereas, there are no such products can satisfy the requirements, the research and experimentation work of the bubble breaker has been carried out in our laboratory.Based on the experience and research result of the previous bubble breaker researcher, this thesis begin to redesign the embarking & fishing bubble breaker, but some unavoidable risks exist in the design process. So in the design, development and utilization process of embarking & fishing bubble breaker, it is necessary to carry out safety evaluation to the embarking & fishing bubble breaker by using the principles of safety system engineering, it can be used to guide the design, reduces the failure and avoids risks.According to the kinetic hydrodynamic calculation principles of the gas liquid mixture and based on the Orkiszewski's gas-liquid pressure gradient forecasting method, the calculation model of flow pattern distribution was established. The calculation program has been developed by using Visual C++, on this basis, a simple flow pattern visualization and simulation software has been developed by loading OpengGL graphic development environment. This software can be used to provide advice for the disposition of bubble breaker; it also can be used to carry out the safety evaluation to bubble breaker after the bubble breaker has been put into oil well. This work is just a basis for the safety evaluation to bubble breaker by using the computer aided simulation technology. Based on the research result of safety evaluation methods used on the equipments, three safety evaluation methods have been chosen to complete the safety evaluation to the bubble breaker system through four phases(installation, put in, utilization and salvage).During the design phase, the possible or the existent risk factors can be recognize by using preliminary hazardous analysis(PHA), based on the analysis, the correction and control measures can be put forward and provide advice to the program; after the determination of program, each part of the system has to be analyzed by using failure mode and effect analysis(FMEA) method, find out the possible failures and kinds, determine the final effect of each failure to the system; at last, based on the analysis result of PHA and FMEA, combine with the fault tree analysis method, carried out quantitative analysis to the established fault tree, find out the main cause of accident and the potential effect factors, and establish the relevant safety measures.