1. Field of the Invention
The invention disclosed herein relates to imaging of subsurface materials and, in particular, to embodiments of electrodes useful for resistivity imaging.
2. Description of the Related Art
Drilling apparatus used for geophysical exploration often include sensors for collecting information about ambient subsurface materials. Sensors may include ones such as those used for resistivity imaging. However, certain problems arise in the use of sensors in a drill string. For example, conventional corrections are performed with calipers and other devices measuring the distance (mechanical, acoustic etc.). The main problem here is the different position of resistivity sensor and caliper, which makes the correction procedure doubtful if vibration occurs.
Therefore, what is needed is a design which offers accurate measurements of standoff at the same position as the resistivity measurements when performing measurement while drilling.