RANGING MEASUREMENTS USING MODULATED SIGNALS.

摘要

A method for performing ranging measurements within a formation includes transmitting an asymmetric time-varying signal from a transmitter (114) disposed within a borehole (106) in the formation. The asymmetric time-varying signal may have a signal characteristic that is based at least in part on a downhole characteristic. A (receiver 110) disposed within the borehole (106) may measure a magnetic field induced on an object (103) within the formation by the asymmetric time- varying signal. A direction to the object (103) from the borehole (106) may be determined based at least in part on the measurement of the induced magnetic field.