Subsurface reservoir with properties staying constant across the reservoir volume: 


Mobility Effective porosity Total compressibility Effective formation thickness


There are no homogenous reservoir in real life but the concept plays important academic role and also has a good number of practical applications to characterize the distributed field properties with some average value. 


See also


Petroleum Industry / Upstream / Subsurface E&P Disciplines / Petroleum Geology / Petroleum reservoir