METHOD FOR DETERMINING ORIENTATION OF DOWNHOLE INSTRUMENT IN BOREHOLE Russian patent published in 2013 - IPC E21B47/24 

FIELD: oil and gas industry.

SUBSTANCE: method for determining orientation of a downhole instrument in a borehole is implemented as per the data of a three-axis accelerometer unit in the borehole section having sufficient inclination for steady work of the accelerometer unit. Turning angle of the sighting point of the downhole instrument is calculated relative to upper side of the borehole and zenith angle of position of the downhole instrument axis. Azimuth angle of position of the downhole instrument is determined as per the inclinometer survey data prior to the performed measurements. Then, in the section of the borehole having sufficient inclination for steady work of the accelerometer unit, there performed is start and uncaging of a gyroscope, the main axis of which is coaxial to the axis perpendicular to the device axis at the uncaging moment. Spatial position relative to cardinal points is calculated for current position of the main axis of the gyroscope through the calculated turning angle of the sighting point of the downhole instrument relative to upper side of the borehole and known azimuth angle of position of the downhole instrument. Then, downhole instrument is delivered to the vertical section of the well, where, using the gyroscope readings, the change of position of the downhole instrument housing relative to the position of the main axis of the gyroscope is determined, and spatial position of the sighting point of the downhole instrument is calculated as per cardinal points.

EFFECT: enlarging the range of use of the downhole instrument at calculation of its orientation as to cardinal points when using it inside the string of steel pipes and in vertical sections.

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