Sensitivities of directional electromagnetic measurements for well placement and formation evaluation while drilling

Abstract

We present sensitivities of first generation of directional loggin‐while‐drilling electromagnetic measurements using tilted and tasverse antenae technology. These measurements are primarily used for pro‐active geosteering, to determine the wellbore position with respect to geological boundaries. They can also be used for enhanced formation evaluation. A novel tool layout with symmetric transmitter‐receiver arrangement is implemented. This configuration enabled removal or amplification of sensitivities to dip, anisotropy and nearby boundaries, resulting in simplified responses and interpretation. In addition, we present how these measurement can be used for determination of structural dip, resistivity anisotropy at any angle, as well as detection fractures and their orientations. Measurement specifics for LWD applications and their relationship to conventional 3D induction couplings are discussed.