page_title: Reflection seismology
section_title: Hydrocarbon exploration
hierarchical_section_title: Reflection seismology / Applications / Hydrocarbon exploration
caption_attribution_description: In marine seismic one or an array of airguns is used to produce sound waves by releasing air under a pressure of 200 bar about every minute. The waves are reflected by the various sediment and rock layers in the ground. The echo is recorded by a streamer which is a some hundred to thousand meter long hose, filled with hundreds of hydrophones in oil, towed to the research vessel.
context_page_description: Reflection seismology is a method of exploration geophysics that uses the principles of seismology to estimate the properties of the Earth's subsurface from reflected seismic waves. The method requires a controlled seismic source of energy, such as dynamite or Tovex blast, a specialized air gun or a seismic vibrator, commonly known by the trademark name Vibroseis. Reflection seismology is similar to sonar and echolocation.
context_section_description: Reflection seismology, more commonly referred to as "seismic reflection" or abbreviated to "seismic" within the hydrocarbon industry, is used by petroleum geologists and geophysicists to map and interpret potential petroleum reservoirs. The size and scale of seismic surveys has increased alongside the significant increases in computer power since the late 20th century. This led the seismic industry from laboriously – and therefore rarely – acquiring small 3D surveys in the 1980s to routinely acquiring large-scale high resolution 3D surveys. The goals and basic principles have remained the same, but the methods have slightly changed over the years.
  The primary environments for seismic hydrocarbon exploration are land, the transition zone and marine:
  Land – The land environment covers almost every type of terrain that exists on Earth, each bringing its own logistical problems.  Examples of this environment are jungle, desert, arctic tundra, forest, urban settings, mountain regions and savannah.
  Transition Zone (TZ) – The transition zone is considered to be the area where the land meets the sea, presenting unique challenges because the water is too shallow for large seismic vessels but too deep for the use of traditional methods of acquisition on land.  Examples of this environment are river deltas, swamps and marshes, coral reefs, beach tidal areas and the surf zone. Transition zone seismic crews will often work on land, in the transition zone and in the shallow water marine environment on a single project in order to obtain a complete map of the subsurface.
  Marine – The marine zone is either in shallow water areas (water depths of less than 30 to 40 metres would normally be considered shallow water areas for 3D marine seismic operations) or in the deep water areas normally associated with the seas and oceans (such as the Gulf of Mexico).
caption: Diagram of equipment used for marine seismic surveys
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