The invention discloses an ultra-deep
well drilling wellbore pressure inversion
correction method, and aims to improve pressure prediction precision and
well control safety in an ultra-deep
well drilling process. The method mainly comprises the following two parts: firstly, establishing a
wellbore pressure calculation model, fully considering the change of
drilling fluid density along with
temperature and pressure based on a
mass and
momentum conservation equation in a
drill rod and an annulus, performing discrete solution on the established
control equation by adopting a
finite difference method, and performing iterative calculation from a well bottom to a well mouth and from the well mouth to the well bottom, so as to obtain a well pressure calculation model; and acquiring pressure and
physical property parameters of each node. Secondly, on the basis of model output, a friction correction factor is introduced, a nonlinear
state space model is constructed, an unscented
Kalman filter (UKF)
algorithm is used for conducting dynamic
estimation on the friction correction factor, and online self-adaptive correction on the
wellbore pressure model is achieved; according to the method, the accuracy of wellbore pressure calculation is effectively improved, and reliable
technical support is provided for ultra-deep well operation.