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r 3 – P ressure Transient Analysis (PTA) -p104/743
Fig. 3.F.2 – Ambiguous model identification
The behaviour of the period that will be analysed is very dependent upon the previous history
and in particular any disturbances immediately before the period in question. If flow rate
changes or small shutin periods immediately prior to the subject period cannot be avoided, at
least the value of the flow rates should be captured. This is a detail that should be stressed in
any test program.
Fig. 3.F.3 – Disturbing the period for analysis
During a buildup that was designed for analysis purposes avoid as far a safety permits any
surface operations that may jeopardize the usefulness of the period. The example below
illustrates a real case where some surface operations affected the buildup period and rendered
it for all practical purposes useless for any analysis with confidence.