Design And Real-time Calculation Of Pressure Control Parameters For Pressure-controlled Drilling Wellbore

Managed pressure drilling technology can safely and efficiently solve the narrow mud weight window drilling problems. At present, this technology has been widely used abroad. The pressure control parameters of Managed pressure drilling, including drilling fluid density. displacement, back pressure and mud cap property, these parameters are the key factors that affect the safety and cost of drilling. In order to improve the wellbore pressure control accuracy and response speed, foreign drilling services company applied high-precision hydraulic model and adaptive control system to Real-time computing wellbore pressure control parameters, but it is a start in China. Accordingly, this paper focus on design and Real-time computing method of Managed pressure drilling wellbore pressure control parameters, which is great significance to the application of Managed pressure drilling.Based on the principle of Managed pressure drilling and wellbore pressure control, this paper developed a series of research on Managed pressure drilling wellbore pressure control parameter design method. The wellbore pressure control mathematical model was established by the analysis of the relationship between the pressure control parameter and formation pressure, which are calculated by iterative method.The results show that, under the pressure conditions of uncertainty, the pressure operation window is used to adjust the pressure control parameters, which can reduce the number of drilling fluid density regulation. In addition, analysis of the drilling fluid rheological model, tool joints, the rotational speed of the drill string and eccentricity, annular cuttings concentration on the annulus of the influence of friction cycles. In order to whittle away the additional factors controlling the parameters of pressure interference and improve Real-time computing accuracy. A wellbore pressure control parameters in Real-time computing model were established by using the moving mass and momentum conservation laws of wellbore fluid. Combining with field data and Unscented Kalman Filter feedback correction model parameters, the model can be used to calculate the pressure control parameters under different working conditions and realize the dynamic control of well bore pressure, which provides the basis for accurately controlling the pressure in the wellbore.According to the research and analysis of pressure control parameter design and Real-time computing method in this paper, an engineering software of pressure control parameter design and Real-time computing software has been developed in C# language of Visual Studio 2013 and SQL Server2008. Drilling fluid density, initial back pressure and height of the mud cap were calculated by using the software, online document input and output are supported.The software has been applied in the design and Real-time computing of pressure control parameters. The simulation results show that, the performance of the software is stable, and real-time correction calculated pressure control parameters of the model results agree well with the measured data. At the same time, it can predict the next stage of pressure control parameters, to provide support for the rapid response and parameter optimization of the Managed pressure drilling, which is helpful to the construction of the site.