Unformatted text preview: urvey. • Mine Clearance: responsible for clear the war explosives before survey. • Recording: Geophysicist who is responsible for data recording. • Quality Control: Geophysicist receives the data everyday to check the quality. Land Survey: Two‐dimensional survey (2‐D): Seismic data or a group of seismic lines acquired individually such that there typically are significant gaps (commonly 1 km or more) between adjacent lines. A 2D survey typically contains numerous lines acquired orthogonally to the strike of geological structures (such as faults and folds) with a minimum of lines acquired parallel to geological structures to allow line‐to‐line tying of the seismic data and interpretation and mapping of structures. 3‐D Survey The seismic data recorded by 2‐D survey is seismic line. Three‐dimensional survey (3‐D): The acquisition of seismic data as closely spaced receiver and shot lines such that there typically are no significant gaps in the subsurface coverage. The seismic data recorded by 3‐D survey is seismic cube. Seismic cube 36 Geology & Geophysics in Oil Exploration Mahmoud Sroor 2‐D Survey Geology & Geophysics in Oil Exploration Marine Survey: 2‐D and 3‐D survey in marine differ from land survey by: ‐The seismic source is Air gun & not dynamite or Vibroseis ‐The seismic detector is Hydrophone & not a geophone ‐The sources and detectors are always at depth below the sea level & the depth of the cable is controlled by Streamer‐Birds ‐The receivers are connected together by streamer. Tail buoy: A floating device used in marine seismic acquisition to identify the end of streamer. It allows the seismic acquisition crew to monitor location and direction of streamers. Streamer Bird: A device connected with the streamer to control the depth of streamer. Types of Seismic arrays (spread): A‐Split dip Spread: the source in center of spaced geophone groups • Split dip Spread: source is inline with geophone groups with no gaps • Deviat...
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- Spring '10
- Geology, Volcano, Tephra, Volcanic Ash, Geology & Geophysics, Mahmoud Ahmed Sroor