Study On Wellbore Flow Model Of Coalbed Methane Vertical Wells

The flow in the wellbore is the basic flow process of oil-gas production,which is not only the reflection of the production performance,but also the theoretical basis of lifting design and production dynamic analysis.And it involves every technical measures in the development process.At present,in the research filed of the wellbore flow model of the CBM vertical wells,the study about the gas-liquid distribution and the flow law in the wellbore is not clear,and the applicable production stage of the model is relatively limited,which has a certain gap with the actual production.Therefore,it is significant to guide the production of CBM by studying the model of CBM wells in different production stages.This dissertation focuses on main production stages of CBM wells that use the tubing to product water and the annual to product gas.The gas-liquid distribution and the flow law in the wellbore is studied.And physical wellbore flow models of the single-phase water flow stage,the two-phase gas-liquid flow stage and the single-phase gas flow stage are built respectively.Based on these,considering gas-liquid distribution and flow pattern changing in the wellbore,mathematical wellbore flow models of three physical models are established by using the fluid mechanics method.Visual Basic 6.0is used to compile the software that can achieve the solving and applying of models.The accuracy and the applicability of the model is verified by combining the practical data of CBM vertical wells of many development fields in Shanxi province.Finally,a CBM vertical wellbore flow model system,which can cover every production stages,is set up.