The reservoir-rock contact surface limiting the size of the permeable petroleum reservoir where the practical fluid flow may occur.
The way producing or or injecting wells respond to the actual reservoir boundary maybe very complex due to limited observation time and cross-well and cross-layer interference.
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There are some production analysis techniques based on long-term flowrate and bottomhole pressure data readings which can reveal the size of the actual petroleum reservoir (see, for example, Multiwell Retrospective Testing).
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