Abstract
During drilling operations poor hole cleaning may result in low drilling efficiency, stuck pipe, problems with well control or even a loss of the wellbore. In this paper a method for warning of poor hole cleaning and stuck pipe is proposed. The method is based on correlating statistical features calculated from bottom hole or stand pipe pressure and torque signals. Especially, the correlation is performed by multiplying the third order moment of bottom hole or stand pipe pressure time series and normalized standard deviation of torque time series. The correlated signal is used as input to a warning generation scheme. This scheme is based on detecting the sign of the correlated signal samples within a moving time window. If the number of positive samples exceeds a predefined threshold a warning is raised. Results of an experimental study on data from three different wells indicate that the proposed statistical method can provide early detection of poor hole cleaning and stuck pipe.
