METHOD DETERMINING AZIMUTH AND ZENITH ANGLE OF WELL AND GYROSCOPIC INCLINOMETER Russian patent published in 2000 - IPC

FIELD: precision instrument making. SUBSTANCE: invention can be used to inspect oil, gas and geophysical wells by movement of down-hole logging instrument in well. It solves problem of increase of precision in determination of azimuth and zenith angle of well, makes it possible to remove limitation from zenith angles thanks to transfer to other formulas determining increment of orientation matrix for zenith angles θ₂> θⁱ> θ₁ based on information from transducers of angular velocity which operate well when zenith angle is close to 90 degrees ( their special point corresponds to θ=0 ). Such joint usage of two methods of which no one work with unspecified zenith angles is possible only if sensitive axis of transducer of angular velocity lies near vertical plane with deviation of 3 to 5 degrees and if kinetic moment is close to horizontal plane. That is why mathematical model of drift of gyroscope is described by simple enough function with constant parameters both for axis of gyrostabilizer and for axis of transducer of angular velocity. This approach makes it feasible to take into account and compensate for corresponding drifts increasing measurement precision by that. Method is realized with use of gyroscopic inclinometer which incorporates ground computer connected by logging cable to down-hole logging instrument. Down-hole logging instrument includes single-axis gyrostabilizer whose platform carries two accelerometers with mutually perpendicular sensitivity axes oriented perpendicular to stabilization axis and two-degree-of-freedom gyro. Angle-data transmitters of gyro are connected to inputs of module measuring angular velocity and stabilization linked with its outputs correspondingly to combined excitation windings of angle-data transmitters, to slaving- torque motor of gyro, to input bus of digital processing unit and to controlling motor kinematically coupled to stabilization axis. Output angle-data transmitter in the form of sine-cosine transformer whose excitation winding and outputs are connected to module of angle converters linked to input bus of digital processing unit is anchored on stabilization axis. Outputs of module of acceleration converters are also connected to bus of digital processing unit and inputs of this module are linked to outputs of accelerometers. Synchronization inputs of modules of angle and acceleration converters, of module measuring angular velocity and stabilization are tied up together and are connected to output bus of digital processing unit. First input of master unit of standard current is also connected to mentioned-above bus. Outputs of master unit are connected to second slaving-torque motor of gyro, input/output bus of digital processing unit is connected to logging cable. Platform of single-axis gyrostabilizer carries third accelerometer whose sensitivity axis coincides with stabilization axis. Output of third accelerometer is connected to proper input of module of acceleration converters. Second input of master unit of standard current is also connected to output bus of digital processing unit to which additional input bus temperature-sensitive elements of accelerometers and two-degree-of-freedom gyro are connected. EFFECT: increased precision of determination of azimuth and zenith angle of well. 7 cl, 7 dwg