Abstract
This study defines an approach to determine porosity, fluid saturations and permeabilities from wireline log data in sandstone reservoirs containing low salinity formation brines. An extensive set of measurements were made on low invasion core were analyzed to establish the ground truth, and to control the input parameter choices for log analysis.
A recently developed water saturation equation, that accounts for the different geometry of the conducting paths along grain surfaces and within the pore fluid, was used to analyze the wireline resistivity logs. This equation predicts far less resistivity contrast between hydrocarbon and water-bearing intervals than other widely used relationships.
The log interpretation technique consists of making robust estimates of highly sensitive parameters such as the cation exchange molarity, Qv, and paying attention to the details in the estimation of the true formation resistivity, Rt and the formation resistivity factor, F.
