An ultra-low noise MEMS accelerometer for seismic imaging

A new MEMS capacitive accelerometer has been developed to meet the requirements for oil and gas exploration, specifically for imaging deep and complex subterranean features. The sensor has been optimized to have a very low noise floor in a frequency range of 1-200 Hz. Several design and process parameters were modified from our previous sensors to reduce noise. Testing of the sensor has demonstrated a noise floor of 10ng/√Hz, in agreement with our predictive noise models. The sensor has a dynamic range of 120db with a maximum acceleration of +/- 80mg. In addition to the performance specifications, automated calibration routines have been implemented, allowing bias and sensitivity calibrations to be done in the field to ensure valid and accurate data. The sensor frequency and quality factor can also be measured in the field for an automated sensor health check.