Patent ID: 6588116
Filing Date: 2003-07-08
Classification: E21B

Abstract:
A method of measuring location while forming a borehole with a drilling tool, the borehole crossing under an earth surface obstacle, the method comprising the steps of:(a) moving an elongate sensor housing having an axis coincident therewith along the borehole to form measurements while drilling under the earth surface obstacle, the housing mounted for common movement with the drilling tool; (b) positioning a rate gyro in said housing wherein said rate gyro forms output signals indicative of measured angular rate and taking a set of measurements to initialize the gyro at a first position; (c) positioning in said housing first and second accelerometers at a right angle therebetween wherein said accelerometers define a transverse plane to the axis of said housing, and forming outputs indicative of values sensed thereby during movement between first and second positions in said borehole; (d) forming subsequent data representative of the outputs of said rate gyro and said accelerometers during movement between said first and second positions along the borehole; (e) forming subsequent accelerometer data representative of said accelerometer output signals, during movement between said first and second positions along the borehole; and (f) converting said rate gyro data and said accelerometer data into a plot of the borehole.