Difference between revisions of "Seismic data: identifying reflectors"
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− | Whether using[[vertical seismic profile| VSP]], [[synthetic seismogram]], or [[log overlay]], the final step is to compare the object to seismic | + | Whether using[[vertical seismic profile| VSP]], [[synthetic seismogram]], or [[log overlay]], the final step is to compare the object to [[seismic trace]]s in the vicinity of the well and find a fit. |
==Example== | ==Example== | ||
− | In [[:file:interpreting-seismic-data_fig12-8.png|Figure 1]], a sonic log has been converted to time and velocity. Note that the time axis on the seismic section and the converted sonic log are linear, while the depth tick marks on the sonic are nonlinear. The geological horizons annotated on the sonic log are located via the depth | + | In [[:file:interpreting-seismic-data_fig12-8.png|Figure 1]], a [[Basic open hole tools#Sonic|sonic]] log has been converted to time and velocity. Note that the time axis on the seismic section and the converted sonic log are linear, while the depth tick marks on the sonic are nonlinear. The geological horizons annotated on the sonic log are located via the depth ticks from picks on other logs ([[Basic open hole tools#Resistivity |
+ | |electric]], [[Basic open hole tools#Gamma ray|gamma ray]], etc.). It is important to realize that a sonic log never goes to the surface; there is always a gap for the [[surface casing]]. So we do not expect time zero on the converted log to fit at time zero on the seismic section. In practice, the log is placed over the seismic section and shifted vertically until we are satisfied with the fit. | ||
[[file:interpreting-seismic-data_fig12-8.png|thumb|{{figure number|1}}. Copyright: Liner, 1999; courtesy PennWell.]] | [[file:interpreting-seismic-data_fig12-8.png|thumb|{{figure number|1}}. Copyright: Liner, 1999; courtesy PennWell.]] |
Revision as of 16:50, 29 April 2014
Exploring for Oil and Gas Traps | |
Series | Treatise in Petroleum Geology |
---|---|
Part | Predicting the occurrence of oil and gas traps |
Chapter | Interpreting seismic data |
Author | Christopher L. Liner |
Link | Web page |
Store | AAPG Store |
Whether using VSP, synthetic seismogram, or log overlay, the final step is to compare the object to seismic traces in the vicinity of the well and find a fit.
Example
In Figure 1, a sonic log has been converted to time and velocity. Note that the time axis on the seismic section and the converted sonic log are linear, while the depth tick marks on the sonic are nonlinear. The geological horizons annotated on the sonic log are located via the depth ticks from picks on other logs ([[Basic open hole tools#Resistivity |electric]], gamma ray, etc.). It is important to realize that a sonic log never goes to the surface; there is always a gap for the surface casing. So we do not expect time zero on the converted log to fit at time zero on the seismic section. In practice, the log is placed over the seismic section and shifted vertically until we are satisfied with the fit.