Seismic method for logging position of a deep borehole in the earth

Abstract

Method and apparatus for logging the position of a deep borehole filled with liquid in the earth, comprising a long, continuous small diameter pipe adapted to be reeled up on a drum mounted on a vehicle, and means to insert the end of the pipe into the mouth of a borehole and to lower it to any desired depth in the earth. A plurality of geophones are positioned on the surface of the earth in the vicinity of the borehole with conventional amplifying and recording means connected thereto. Means are provided on the vehicle for compressing a liquid or gas, and injecting it into the pipe. On the bottom end of the pipe is a chamber in which this pressurized fluid can be stored. Fast acting valve means are provided which on signal can suddenly open and permit the stored fluid in the chamber to explosively expand into the liquid in the annulus of the borehole. Such explosive injection of the fluid from the chamber into the well will cause a seismic wave to be generated which will expand until it reaches the surface and is detected and recorded by the geophones. Electrical control wires may be carried in the pipe means by which the valve can be timed and controlled, so that the travel times of the seismic wave from the chamber to the geophones can be determined, from which the position of the borehole at the depth of the chamber can be determined.