COMBINED LOGGING AND SEISMIC DOWN HOLE TOOL

摘要

A combined seismic (62) and logging tool (60), and a method for running a seismic survey and a log during a single trip into the borehole. A logging tool (60) and seismic tool (62) are connected to form a downhole tool (10), with the seismic tool (62) containing switching circuitry which alternatively activates and deactivates the seismic tool (62) and the logging tool (60). The switching circuitry operates by activating the seismic tool (62) when a direct current is received from the cable, and deactivating the seismic tool and activating the logging tool when an alternating current is received from the cable (24). A bow spring (70) is attached to the side of the seismic tool (62) to bias the downhole tool (10) into contact with the walls (26) of the borehole (20).