A Pressure Control Modeling Approach for Managed Pressure Drilling Using Matlab

In this paper,a pressure control modeling approach using Matlab was studied to improve the pressure control accuracy of managed pressure drilling.Firstly,throttling control pressure principle of throttle valve was analyzed,the equation representing physical characteristics of throttle valve was established on the basis of Bernoulli’s equation.To do so,it was necessary to acquire throttling control pressure experiment data of throttle valve and to develop a four-parameter equation that could be used to calculate the pressure control of throttle valve.This was done by means of linear regressions using Matlab software.Second,the relation equation between the opening and throttling areas of the throttle valve was established by using Matlab software which perform goodness of fit analysis based on the characteristic curve of opening and equivalent diameter of the throttle valve selected in this experiment.Third,the opening and switching time data of the throttle valve was collected from its on-off experiment,and the relation equation between the opening and switching times was developed by using Matlab software fitting,and the theoretical model of throttling control pressure was finally established by combining above-mentioned equations.And fourth,the model was translated into the universal real time code by using the semi-physical simulation plug-in of Matlab software and the automatic control software for managed pressure drilling was prepared by adopting the modularized modeling method.In this way,the pressure control model was constructed.It was verified by a circulation analog system that this model could meet the fine pressure control requirements of managed pressure drilling with the response time of control system less than 10 s and the automatic control pressure accuracy ±0.2 MPa.It is proved that this Matlab based pressure control modeling approach for managed pressure drilling is viable.