Changes

===Base map preparation===

===Base map preparation===

Technical data are surveyed and locations positioned most commonly by latitude and longitude. Coordinate projection schemes attempt to redefine latitude and longitude positions, as they would appear on a sphere, to some ''x''–''y'' reference system converted to a flat plane. The reason for this conversion is ease and speed of data manipulation and posting. Latitude and longitude data are in degrees, while ''x''–''y'' systems are in decimals<ref name=pt08r5>Coffeen, J. A., 1990, Seismic on screen—an introduction to interactive interpretation: Tulsa, OK, Pennwell Books.</ref>. A common projection system for positioning all project data (including proprietary seismic, contractor seismic, well, and cultural data) is critical for the relationship of multiple data sets and proper base map displays (Figure 1). Without a common projection system, one cannot reliably integrate multiple ''x''–''y'' data sets for display. Lacking this relationship, ''z'' information cannot be related properly for interpretation. Files containing technical base map information include seismic survey data, well location data, and reference annotation. The relationship files reside separately from the data files, allowing for seismic lines and well data to be posted on a base map. Technical data files that contain the ''z'' information, such as seismic traces and well deviation data, are linked to the ''x''–''y'' location files.

[[file:two-dimensional-geophysical-workstation-interpretation-generic-problems-and-solutions_fig1.png|left|thumb|{{figure number|1}}Base map preparation: critical and noncritical.]]

[[file:two-dimensional-geophysical-workstation-interpretation-generic-problems-and-solutions_fig1.png|thumb|{{figure number|1}}Base map preparation: critical and noncritical.]]

Technical data are surveyed and locations positioned most commonly by latitude and longitude. Coordinate projection schemes attempt to redefine latitude and longitude positions, as they would appear on a sphere, to some ''x''–''y'' reference system converted to a flat plane. The reason for this conversion is ease and speed of data manipulation and posting. Latitude and longitude data are in degrees, while ''x''–''y'' systems are in decimals<ref name=pt08r5>Coffeen, J. A., 1990, Seismic on screen—an introduction to interactive interpretation: Tulsa, OK, Pennwell Books.</ref>. A common projection system for positioning all project data (including proprietary seismic, contractor seismic, well, and cultural data) is critical for the relationship of multiple data sets and proper base map displays ([[:file:two-dimensional-geophysical-workstation-interpretation-generic-problems-and-solutions_fig1.png|Figure 1]]). Without a common projection system, one cannot reliably integrate multiple ''x''–''y'' data sets for display. Lacking this relationship, ''z'' information cannot be related properly for interpretation. Files containing technical base map information include seismic survey data, well location data, and reference annotation. The relationship files reside separately from the data files, allowing for seismic lines and well data to be posted on a base map. Technical data files that contain the ''z'' information, such as seismic traces and well deviation data, are linked to the ''x''–''y'' location files.

Initial project size and addition of data during interpretation is a prime factor to consider in the preparation phase of any 2-D project. With some software, project size is often awkward to modify. For example, detailing a prospect may demand more seismic data, and the additional profiles may not be available at project creation time. A 2-D project should be created of such a size that new data could easily be added when required (Figure 1).

Initial project size and addition of data during interpretation is a prime factor to consider in the preparation phase of any 2-D project. With some software, project size is often awkward to modify. For example, detailing a prospect may demand more seismic data, and the additional profiles may not be available at project creation time. A 2-D project should be created of such a size that new data could easily be added when required ([[:file:two-dimensional-geophysical-workstation-interpretation-generic-problems-and-solutions_fig1.png|Figure 1]]).

Anticipating the availability of various seismic display types (such as stack, migration, inversion, or attribute) is facilitated by creating several data files, each containing a different process. This allows the user to select which data type to work with. Addition of seismic data files is simple and can be done at any time during a project.

Anticipating the availability of various seismic display types (such as stack, migration, inversion, or attribute) is facilitated by creating several data files, each containing a different process. This allows the user to select which data type to work with. Addition of seismic data files is simple and can be done at any time during a project.