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Dynamic Data Analysis – v5.12.01 - © KAPPA 1988-2017
Chapte
r 3 – P ressure Transient Analysis (PTA) -p115/743
Column (2) and (3) are read directly from the difference channel from the quality control plot.
Column (4) is the differential gradient calculated from column (3). Column (5) and (6) are
intelligent guesses or assumptions by the user that will normalize column (8), i.e. the same
implied gauge offset applies whatever the assumed fluid phase is present.
The implied offset is then entered by the user in its appropriate box below the table, and the
residual differences will become close to zero or zero, if the correct assumption as to the fluids
present in the wellbore have been made.
The implied offset becomes the gauge offset which has to be within the gauge specifications to
be acceptable to the operator.
This analysis gives a much better idea as to which of the fluid gradients to use to correct the
gauge pressure to top of sandface.
Another product of this approach is being able to decide which part of the data is really valid
for pressure transient analysis as all data affected by the segregation or fluid movements must
be discounted in the interpretation process. The impact of not knowing and understanding the
wellbore environment is now described.