Changes

  | part    = Predicting the occurrence of oil and gas traps

  | part    = Predicting the occurrence of oil and gas traps

  | chapter = Interpreting seismic data

  | chapter = Interpreting seismic data

  | frompg  = 12-1

  | frompg  = 12-8

  | topg    = 12-29

  | topg    = 12-9

  | author  = Christopher L. Liner

  | author  = Christopher L. Liner

  | link    = http://archives.datapages.com/data/specpubs/beaumont/ch12/ch12.htm

  | link    = http://archives.datapages.com/data/specpubs/beaumont/ch12/ch12.htm

  | isbn    = 0-89181-602-X

  | isbn    = 0-89181-602-X

}}

}}

Seismic prospecting has been around since the 1920s and was almost exclusively two-dimensional until the mid-1980s.  Three-dimensional techniques were experimented with as early as the 1940s but did not progress far until [[digital processing]] became common in the 1970s. Current worldwide seismic effort is estimated to be over 50% 3-D, and the percentage is growing rapidly. This estimate would apply to both dollar volume and acquisition effort. International (non-U.S.) seismic prospecting could be as high as 75% 3-D. We live in a 3-D world and now understand that 2-D seismic data can have many pitfalls and problems. (For more information on interpretation of two-dimensional data, see [[Two-dimensional geophysical workstation interpretation: generic problems and solutions]].)  The 3-D seismic technique yields much more information  than an equivalent amount of 2-D seismic and can reduce [[Reducing exploration risk|risk]].

Seismic prospecting has been around since the 1920s and was almost exclusively two-dimensional until the mid-1980s.  Three-dimensional techniques were experimented with as early as the 1940s but did not progress far until [[digital processing]] became common in the 1970s. Current worldwide seismic effort is estimated to be over 50% 3-D, and the percentage is growing rapidly. This estimate would apply to both dollar volume and acquisition effort. International (non-U.S.) seismic prospecting could be as high as 75% 3-D. We live in a 3-D world and now understand that 2-D [[seismic data]] can have many pitfalls and problems. (For more information on interpretation of two-dimensional data, see [[Two-dimensional geophysical workstation interpretation: generic problems and solutions]].)  The 3-D seismic technique yields much more information  than an equivalent amount of 2-D seismic and can reduce [[Reducing exploration risk|risk]].

==3-D advantages==

==3-D advantages==

* Map view of [[Reservoir quality|reservoir properties]]

* Map view of [[Reservoir quality|reservoir properties]]

* Much better areal mapping of [[fault]] patterns and connections and delineation of [[reservoir]] blocks

* Much better areal mapping of [[fault]] patterns and connections and delineation of [[reservoir]] blocks

* Better lateral resolution (2-D suffers from a [[cross-line]] smearing, or [[Fresnel zone]], problem)

* Better [[lateral]] resolution (2-D suffers from a [http://wiki.seg.org/wiki/Crossline_smearing cross-line smearing], or [http://wiki.seg.org/wiki/Dictionary:Fresnel_zone Fresnel zone], problem)

==Data sets==

==Data sets==

A 3-D seismic data volume is like the room-temperature example except for two changes:

A 3-D seismic data volume is like the room-temperature example except for two changes:

* The vertical axis is two-way traveltime, not depth.

* The vertical axis is [http://wiki.seg.org/wiki/Dictionary:Traveltime two-way traveltime], not depth.

* The data values are [[seismic amplitude]]s rather than temperature.

* The data values are [http://wiki.seg.org/wiki/Dictionary:Amplitude seismic amplitudes] rather than temperature.

==3-D data set example==

==3-D data set example==

[[file:interpreting-seismic-data_fig12-3.png|left|thumb|{{figure number|1}}3-D data from north Texas. From Liner.<ref name=Liner_1999>Liner, Chris, Elements of 3-D Seismology: Tulsa, PennWell.</ref> Courtesy PennWell.]]

[[file:interpreting-seismic-data_fig12-3.png|thumb|500px|{{figure number|1}}3-D data from north Texas. From Liner.<ref name=Liner_1999>Liner, C., 1999. Elements of 3-D Seismology: Tulsa, PennWell.</ref> Courtesy PennWell.]]

Let's take our example a step further. Think of a 3-D seismic data set as a box full of numbers, each number representing a measurement (amplitude, for example). Each number has an (''x, y, z'') position in the box. For any point in the middle of the box, three planes pass through it parallel to the top, front, and side of the box.

Let's take our example a step further. Think of a 3-D seismic data set as a box full of numbers, each number representing a measurement (amplitude, for example). Each number has an (''x, y, z'') position in the box. For any point in the middle of the box, three planes pass through it parallel to the top, front, and side of the box.

[[Category:Interpreting seismic data]]

[[Category:Interpreting seismic data]]