Automated field testing of 3-C geophones using a 3-C microvibrator

Henry C. Bland

Existing techniques for determining the 3-component (3-C) geophone orientation, channel assignment, and polarity in land seismic surveys are problematic. The current technique of tap testing is fraught with difficulties due to the large amount of human intervention required to successfully perform the test in the field. Additional problem frequently occur as a result of poor communication of field test results to the seismic data processor. An apparatus is proposed to solve this problem. It uses three orthogonally oriented, rotating microvibrators to form a 3-C microvibrating source. After performing an automated field test, the data are passed through a simple processing flow. The output of that processing flow can be used as the basis of an automatic orientation and polarity determination system. A prototype 3-C microvibrator was constructed and its output is recorded with a 3-C geophone. A field test indicates that the technique shows promise, but refinements are necessary in order to produce a robust, automated solution.