Method for controlling well bore pressure based on model prediction control theory and systems theory

摘要

A method for controlling well bore pressure based on model prediction control theory and systems theory, which belongs to the field of well bore pressure control technique, includes: detecting a well bottom pressure, a stand pipe pressure, a casing pressure, an injection flow rate and an outlet flow rate during construction process, and determining the presence of overflow or leakage; if there is no overflow or leakage, then fine-adjusting the wellhead casing pressure according to the slight fluctuations of the well bottom pressure, the stand pipe pressure or the casing pressure, ensuring that the well bottom pressure, the stand pipe pressure or the casing pressure are at a set value; if there is overflow or leakage, then using a well bore multi-phase flow dynamic model to simulate and calculate the overflow or leakage position and starting time of the overflow or leakage, predicting the variation over a future time period of the well bore pressure in the well drilling process, and utilizing an optimization algorithm to calculate the control parameter under a minimum of an actual well bottom pressure difference during the future period; and repeating the optimization process for the next time period after a first control parameter is selected and set. The present method enables the well bore pressure to be controlled within the allowable fluctuation range of a project, thus achieving precise pressure control.