A Review of Seismic-While-Drilling (SWD) Techniques: A Journey From 1986 to 2005

Abstract

Abstract Seismic While Drilling (SWD) specifically encompasses the seismic techniques operated while the drillstring is lowered in the borehole, during effective drilling, during maneuvers or while connecting drill pipes. This paper provides a State of the Art review on both old and newer SWD techniques used by the Industry. In the past 21 years (1986-2006), the Drill-bit SWD technique practiced by the industry utilizes the acoustic energy radiated by the Tri-Cone bit to provide vital real time information during drilling by providing time-to-depth and look-ahead information Another emerging technique which is being used mainly by Schlumberger since 2000 is Vertical Seismic Profile While Drilling (VSP-WD), which consists in recording the seismic signal generated by a surface seismic source on seismic sensors integrated inside the downhole Borehole Assembly (BHA). Two efficient wireline VSP which could be assimilated to SWD techniques and which are not be discussed in this paper are the technique of Tube Logging Conveying or Tough Logging Condition (TLC), in particular the TLC-VSP and the standard wireline logging technique of Intermediate VSP. Recently introduced Swept impulse hydraulic tool is capable of generating a broadband seismic signal at the bit while drilling. This tool overcomes the limitations of drill-bit seismic particularly in soft formations and in inclined holes by allowing seismic operations with PDC bit. Operating principles, seismic processing and results of a field demonstration of seismic profiling while drilling in a shallow well are described in this paper. The two major issues that need to be understood in order to make these seismic measurements with precision and reliability are also raised in this paper. This paper aims to give a present day picture of the SWD techniques. Data acquisition and sensor deployment strategies are discussed in some detail. The benefits of SWD are demonstrated by means of several field examples, showing how the data can be used to reduce drilling costs, predict drilling hazards and improve efficiency of drilling operations on a real time basis. The operating domain of SWD technique is identified along with the current limitations. Future development directions are also proposed.