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Introduction

Depth conversion of time data into depth data can also be performed for 2D seismic lines. It utilizes in principle the same basic techniques as desribed described in Depth Conversion of time surfaces. In addition extra attention is paid to transforming the wavelets into a new wavelets form using spline based algorithms.

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Formula for depth conversion

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Info
titleStandard formula for depth conversion:
  • Seismic_lines_in_depth = Seismic_lines_in_time x Velocity

The seismic linesare lines are depth converted according to the corresponding velocity field. The velocity field describing the input velocity can be:

Info
titleVelocity options:
  • Time-velocity cube
  • Stacking velocity data along the same line
  • Lookup curve fory for y (time) to x(depth)
  • Constant velocity in meter per second

Command menus for

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seismic depth conversion

Seismic lines (or seismic sections as they are also called) is organized under a folder having the schema Seismic Data. The seismic lines themselves have schema Seismic Line.

The following command menus for depth conversion of seismic lines are present:

Notetip
tiletitleCommand menus for depth conversion of *Seismic Lines*
  • seismic lines in a folder->Depth conversion of seismic in a folder. Allows for depth conversion of all seismic lines in a folder.
  • seismic line->Seismic depth conversion. Will convert a single seismic line.

The menu contents are basically the same in the trwo two cases and should be easy understandable. A few comments are described below.

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To achieve a satisfactory depth conversion apply a smooth velocity field or a smooth velocity cube. It is assumed that the velocity data is covering the seismic outline. If not, the depth conversion will use the nearest velocity data that is covered by the outline.

The generation of a time-velocity cube and trimming towards check shot wells is described in Cube gridding from stacking velocities.

Output

A new outline is generated after depth conversion for each seismic line. This The new outline makes a rectangular frame from top to the specified depth.

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The seismic lines are depth converted following these principles:

Info
Depth converted seismic lines
Depth converted seismic lines
  • Seismic lines that have an outline within the velocity field are depth converted and saved back into the project.
  • The default option is to create a new folder bearing the same name with the extension _depth.
Otherwise one can
  • If saved back into the same data the converted depth seismic will override the
input
  • time seismic
with the depth seismic
  • . In that case, make sure that you work on copies of the original seismic
sections
  • lines in time.
  • It is thus necessary to take a copy of the complete folder with seismic sections and run this command object on the folder doing a depth conversion on all seismic sections in the folder.
  • Seismic sections that are not depth converted if they are outside the cube or velocity field are listed in the message area.

A time-velocity cube was gridded from stacking velocities. A seismic lines was depth converted.

The seismic line before and after depth conversion is arranged in a connected viewport presentation showing the same coordinate area of the result.

One sees that the depth data is greater in value than the time data.
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Time-velocity cube located outside the coast

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Details of a seismic line converted from time to depth