Initial tests with a new directional survey tool show a significant enhancement in attainable accuracy over conventional instrumentation. Two prototype systems, developed over the last two years by Gyrodata, Inc., have recently been tested in a well in West Texas. Although many more tests are required, preliminary results indicate that the original design objective for borehole position uncertainty less than 1.7 feet per 1,000 feet of hole–has been met.

The Gyrodata Wellbore Surveyor employs an inertial grade rate gyro adapted from the aerospace industry. In combination with its other sensors and electronics, the device can sense the orientation of the earth's spin vector at each independent survey station. As a result, the major systematic errors associated with conventional gyros–geographical reference and unaccountable drift–are eliminated. Other sources of inaccuracy are minimized by the system's measuring techniques and operational procedures, and additional benefits should arise from faster survey speed and increased reliability. A true north reference device can also employ a small outside diameter since it requires only one gyro and one accelerometer, rather than the two or three of each needed in an inertial navigation system.

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