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The performance of horizontal and vertical wells in 12 Canadian oil pools wasreviewed to determine the likely range of ultimate recovery for individualwells. These pools were dissimilar in terms of their lithology, drivemechanisms and oil density.
Productivity Improvement Factors (PIF, the ratio of production of a horizontalwell to a vertical well for the first 12 months) and the key benefit(incremental oil recovery versus acceleration) of horizontal wells were alsoexamined.
Overall, the horizontal wells declined rapidly within the first year to about40 percent of the peak rate and subsequently a flatter decline becameestablished. PIFs for the horizontal wells appear distributed in a log normalfashion, in spite of many variables affecting their performance. It also becameobvious that, in general, the best horizontal wells were drilled first in eachpool.
These findings are expected to be of value in decisions on continuing orterminating a pool development program involving horizontal wells and inestimating reserves based on limited production information.