1. n. [Formation Evaluation]
The resistivity measured by an electrode device. The term often is used to distinguish this resistivity from that measured by the measurements-while-drilling propagation resistivity, or the wireline induction resistivity. The term may also refer to measurements-while-drilling toroid devices, such as bit resistivity, ring resistivity, and button resistivity. These devices do not use electrodes but have a similar response. Electrode resistivity measurements respond to resistivity, not conductivity. They are therefore best at measuring true formation resistivity at high resistivities, high contrasts in resistivity between formation and drilling mud, and for conductive invasion. These are conditions that are not well covered by propagation and induction resistivity.