Drill-bit seismic with downhole sensors

摘要

A drill-bit seismic method where the seismic receivers are located in the BHA. The data detected by these receivers is processed by a downhole processing unit in order to estimate the interval velocity of the seismic wave between the sensors and between the bit and a sensor. Additionally, the processed data might provide the distance to a seismic reflector close to the borehole and the average seismic velocity between the well and this reflector. The processed data can be transmitted to surface location by mud-pulse telemetry. The pilot signal can be also used to process seismic data recorded by receivers located at the earth surface (or close to it).

主权项

1. A method of evaluating an earth formation, the method comprising:
conveying a bottom hole assembly (BHA) into a borehole and using a drillbit for generating an unknown seismic signal into the formation; receiving signals at at least two spaced apart sensors on the BHA responsive to the generated seismic signal; and using at least one processor for:
processing the received signals at the at least two spaced apart sensors and estimating the generated seismic signal.