基于Matlab的控压钻井压力控制建模方法

A Pressure Control Modeling Approach for Managed Pressure Drilling Using Matlab

为了提高控压钻井的控压精度,研究了基于Matlab的控压钻井压力控制建模方法。分析了节流阀的节流控压原理,根据伯努利方程建立了表征节流阀物理特性的方程;利用采集的节流阀节流控压试验数据,通过Matlab软件进行线性回归,得到了可计算节流阀控压的四参数公式;根据试验选用的节流阀开度与当量直径的特性曲线,采用Matlab软件进行拟合,得到了节流阀开度与节流面积的关系方程;根据节流阀开关试验得到的节流阀开度与开关时间数据,利用Matlab软件拟合出了开度与开关时间的关系方程,将上述各方程相结合得到了节流控压的理论模型。利用Matlab软件的半实物仿真插件将模型转化为通用实时代码,并采用模块化建模方法,编制了控压钻井自动控制软件,形成了控压模型。循环模拟系统验证显示,控制系统的响应时间小于10s,控制精度达到了±0.2MPa,满足控压钻井精细控压的需求,这证明基于Matlab的控压钻井压力控制建模方法是可行的。

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 open- ing and equivalent diameter of the throttle valve selected in this experiment. Third, the opening and switc- hing time data of the throttle valve was collected from its on-off experiment, and the relation equation be- tween 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.