FIELD: soil or rock drilling; mining.
SUBSTANCE: drilling string in a borehole, comprising: a micro-resistive caliper to determine values of deviations between the drill string and the wellbore wall, wherein the micro-resistive caliper includes: a cylindrical housing; a plurality of central electrodes arranged circumferentially around the cylindrical housing for emitting electric flow to the well and towards the wellbore wall; several focusing electrodes for limiting the electric flow dispersion emitted by the central electrodes, wherein each of the focusing electrodes surrounds its central electrode; and a plurality of return electrodes for receiving an electric stream emitted by the central electrodes, wherein each of the return electrodes surrounds its focusing electrode, an ultrasonic caliper to determine the borehole wall roughness profile; and one or more processors connected to the micro-resistive and ultrasonic caliper to correct the roughness profile using the value of one or more radii of the wellbore, location of the center of the wellbore and the above values of deviations, wherein it is possible to determine the location of the center of the wellbore or the radius of the wellbore through one or more processors, using the deviation values, the radius of the micro-resistive caliper and the orientation of one or more of the multiple back electrodes to determine the coordinates of one or more points of contact of said electric flow on the wall of the wellbore.
EFFECT: invention relates to determination of borehole parameters using ultrasonic and micro-resistive caliper gauges.
9 cl, 12 dwg
