ATTITUDE REFERENCE FOR TIEBACK/OVERLAP PROCESSING

摘要

A method for calculating orientation changes within a borehole using a gyro sensor to detect angular deflection rates in an attitude reference interval as a MWD system is moved from a first to a second location within the borehole. A compass shot may be taken at one or more of the first and second locations using a magnetometer and accelerometer or gyro sensor and accelerometer. Tieback and/or overlap processing may be applied to increase the accuracy of measured orientation within the borehole. Additionally, tieback and/or overlap processing may be applied to adjust sensor model parameters in response to discrepancies between calculated and measured locations. Iterated calculations of orientation change between subsequent intervals may allow MWD orientation to be computed for an entire drilling operation using only a single compass shot.

主权项

1. A method comprising:
providing a MWD system, the MWD system including multiple sensors, the data collected by the sensors interpreted by sensor models having adjustable sensor model parameters, the MWD system having an orientation, the orientation including azimuth and inclination; positioning the MWD system on a drill string; positioning the drill string at a depth within a borehole drilled from a surface location, the depth measured from the location of the MWD system to the surface location, the direction of the borehole generally being represented by the orientation of the MWD system; moving, by a motion of the drill string, the location of the MWD system within the borehole from a first depth to a second depth; sensing changes in the orientation of the MWD system using one or more sensors of the multiple sensors as the MWD system is moved from the first depth to the second depth; and calculating the change in orientation of the MWD system between the first and second depths using the sensed changes in the orientation of the MWD system.