Method to look ahead of the bit

摘要

The present disclosure is direct to method of performing measurements while drilling in an earth formation. The method may include estimating a location of a seismic reflector using signals from one or more of seismic sensors located at a plurality of locations in a borehole and the drilling depth of the one or more seismic sensors in a borehole. The signals may include information about times when the seismic sensors detect a direct wave and a reflected wave. The method may include storing the information in a memory using a processor.

主权项

1. A method of performing measurements while drilling in an earth formation, the method comprising:
estimating a location of a seismic reflector using (i) a plurality of signals from at least one seismic sensor, each signal being generated at a unique drilling depth and indicative of a direct wave and a reflected wave, and (ii) the at least one unique drilling depth for the at least one seismic sensor, wherein estimating the location of the seismic reflector comprises:
assigning an arbitrary value to each arrival time of the direct waves detected from the plurality of signals;determining an associated time gap between each arrival time of the direct waves and the reflected waves for the at least one seismic sensor from the plurality of signals;generating a curve, using a regression calculation, that fits the associated time gaps at unique drilling depths for the at least one seismic sensor; andestimating the location of the seismic reflector using an intersection point along the curve.