Versatile Gyroinclinometer Based on a Single Axis Angular Rate Sensor

Abstract

Introduction. Currently, the versatility and reliability of gyroscopic inclinometers (GI), more than accuracy, determine their configuration and design. Imperative conditions for versatility include a diameter of 42…44.5 mm and a combination of point and continuous survey modes. Reliability is primarily determined by the robustness of the main elements. The fundamental parameter is adaptability to the trajectory, in other words, equal accuracy in the operating range of zenith angles, which determines the choice of orientation of the angular velocity sensors (ARS) with incomplete (< 3) number of their axis. Presently, biaxial dynamically tuned gyroscopes (DNG) are widely used due to their dimension and accuracy criteria; however, their elastic suspension gradually degrades as a result of frequent sidetracking operations (from previously drilled ones) accompanied by high-intensity impacts.Aim. To develop an inexpensive versatile GI that maintains a balance between shock resistance and accuracy (com[1]parable to fiber-optic ARS) based on a single-axis vibrating ring gyroscope (VRG) with an induction-type resonator made using MEMS technology.Materials and methods. The method of multi-position compassing with a single uniaxial ARS was implemented by transition from simultaneous biaxial measurements to uniaxial measurements in five successive positions of the frame (through 90°) along the toolface angle. Experimental data on the drifts of the selected VRG allow statistical methods to be used to construct an Allan-variance plot to confirm that the proposed method does not increase the total compassing time compared to the basic one. The continuous mode of such a GI, studied by solving differential equations, requires holding the input axis of the ARS near the apsidal plane using the same rotating frame.Results. The obtained ratios confirm that the performance characteristics of a GI with a uniaxial ARS approximately correspond to the conventional biaxial scheme. These conclusions were also confirmed by the mathematical modeling of a survey of a typical oil and gas well.Conclusion. The described GI containing a single ARS with indirect stabilization of the input axis is the result of a consistent development of the approach to the use of incomplete information

Keywords

• gyroinclinometer
• longitudinal scheme
• two-axis ars
• single-axis ars
• dynamically tuned gyroscope
• vibrating ring gyroscope