Oil cross-flow from highly permeable zones to low-permeability wells h
as assessed using a method which helps define water-flood collector vo
lumes and also assesses reserve depletion extent. Concurrent perforati
on of beds widely differing in permeability has revealed that oil infl
ow occurs only from the easiest wells, thus resulting in larger well s
pacing, 1.4 wider than originated from a design.