Wettability

Logic provides a value for n for non-strongly water wet reservoirs

A value for mixed wettability n: Many oil reservoirs have mixed wettabilities. These will have Sw’s below those implied from conventionally cleaned, strongly water wet, capillary pressure Sw-Ht data. If we reverse calculate n from these high capillary pressure Sw’s using log data, apparent n will be high: we shall be assuming a higher Sw for the logged resistivity. Conversely, for the conventionally cleaned and hence strongly water wet electrical special core analysis on these same plugs their apparent n will be low: water wet systems have low n’s. These two observations provide a means to constrain n and largely overcome worries for dm-m scale n in mixed wet reservoirs. This information is probably sitting behind you on your shelf right now.  Data is always trying to tell us something but we aren’t always listening