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Line 27: − {| class = "wikitable"+ − |-+ − ! Step || Action+ − |- − | 1 || Find the purest shale intervals on the GR or SP base line. They must be reasonably thick to allow valid responses of the other logs and free of sand or lime stringers. (See points a–e, [[:file:formation-fluid-pressure-and-its-application_fig5-20.png|Figure 1]].) − |- − | 2 || At the same depth, mark the value of resistivity, conductivity, sonic travel time, or density. − |- − | 3 || Note any series of these best shale values vs. depth. These define a normal shale trend (NST) line for each of the log curves to be used. − |}
Pressure prediction: analysis of well-log and seismic data (view source)
Revision as of 16:35, 28 October 2014
, 16:35, 28 October 2014→Procedure: analyzing well logs
To locate intervals with potentially abnormal fluid pressure, use the following procedure.
To locate intervals with potentially abnormal fluid pressure, use the following procedure.
# Find the purest shale intervals on the GR or SP base line. They must be reasonably thick to allow valid responses of the other logs and free of sand or lime stringers. (See points a–e, [[:file:formation-fluid-pressure-and-its-application_fig5-20.png|Figure 1]].)
# At the same depth, mark the value of resistivity, conductivity, sonic travel time, or density.
# Note any series of these best shale values vs. depth. These define a normal shale trend (NST) line for each of the log curves to be used.<br>
''' Note: ''' Departure from the NST line indicates abnormal microporosity due to abnormal pore pressure.
''' Note: ''' Departure from the NST line indicates abnormal microporosity due to abnormal pore pressure.
==Diagram of log response to overpressure==
==Diagram of log response to overpressure==