| Abstract | Navigational mapping of subsurface holes drilled for oil and gas production is required by law. Currently, mapping a drilled hole requires the use of expensive gyroscopes to determine azimuthal direction (e.g., North, West etc.). However, MEMS (micro-electro-mechanical-systems) gyros are now commercially available and are orders of magnitude less expensive than current downhole spinning mass gyros. Unfortunately, they are not accurate enough to be used for downhole mapping. Determining the azimuth of a subsurface hole requires a gyro to measure a component of the rotation of the earth. At Fort Worth's latitude, a gyro pointed North would measure a rotation rate of 0.0035 degrees/second; while a gyro pointed East would measure zero degrees/second. Unfortunately, the drift of MEMS gyro-measured rotation rate is much larger than earth's rotation rate. Our experimental work indicates that MEMS gyro signals can be averaged and combined to improve the signal-to-noise ratio and subsequently reduce error. |
