Optimization And Application To Calculation Model Of Wellbore Pressure By Managed Pressure Drilling

The thesis investigates and analyses the technology of managed pressure drilling (MPD), familiarize and grasp the commonly-used MPD system at home and abroad, analyze and evaluate its current situation and development direction of MPD system. There are three successful systems which applied in MPD practice abroad:dynamic annular pressure control system of Schlumberger, the MPD system of Halliburton and system of micro-flow managed pressure drilling of Weatherford. After analyzing the technical features of three managed pressure drillings, it showed that micro-flow managed pressure drilling has its own unique advantages from the aspects of well control security, penetration rate improving, exploration and protection of oil and gas layer and application versatility. Domestic research on MPD started late, there is still a large gap in terms of the depth of the study, the maturity of the technology and home-made rate of core equipment. Therefore, the urgent measures should be taken to accelerate the pace of research on the basic theory of micro-flow MPD. Combined with micro-flow MPD characteristics at home and abroad, the thesis studies the micro-flow MPD principles, system composition and technology research, focusing on the establishment of wellbore pressure’s computational model of micro-flow MPD, and calculation results are validated based on specific instance.On the basis of the mass data at home and broad as well as the comprehensive consideration of the factors affecting the calculation of the wellbore pressure of MPD, this thesis tries to build a calculation model for the drilling hydraulic parameters of fluid in different rheological models. At the same time, by completely considering the technology and site construction situation of managed pressure drillings, the paper tries to classify the micro-flow managed pressure drillings according to different operating modes in order to determine the formula for the calculation of wellbore pressure. What’s more, under the direction of the managed pressure drilling softwares and the designs of calculation methods for the wellbore pressure exist at home and abroad, as well as the mode of’"flow pattern’+’process’+’operate mode’", calculation model of the wellbore pressure of managed pressure drillings comes out. The author tries to develop a set of micro-flow managed pressure drillings software with multiple functions—the data management of micro-flow managed pressure drillings, real-time calculation of bottom hole pressure, real-time update and show of key parameter and fluctuations of all kinds of pressure flows, personalized compilation of graphics and curves, the output of historical data reports and the interface operation of micro-flow on the basis of Microsoft SQL Server2008database platform and object-oriented visual programming tool.With the help of basic information of2015well in a certain oil field (well structure, bottom hole assembly and drilling fluid parameters, etc.), this paper firstly optimized the best rheological model, many ideas and results are given to wellbore pressure in the rheological model under various working conditions, expressed the change in wellhead pressure along with its depth in the form of the chart. Calculation results are validated with the calculation model of Wellbore pressure which applied in the thesis based on the comparative analysis between the calculated and actual application value in order to meet on-site construction requirements, which has a guiding role to site construction of micro-flow managed pressure drilling.