New Insights from 10-Years-Stored Plugs Improve Log Water Saturation Estimation in a Tight Carbonates in Libya

Abstract

Summary The Garian reservoir is a low porosity, low permeability, locally fractured carbonate reservoir consisting mainly from limestones and dolomites. Log water saturation throughout the reservoir is highly uncertain and does not compare well with core water saturation. It is thought that the resistivity measurements conducted on few plugs cut from the first well drilled and used for evaluation are not adequate, and that the derived Archie parameters are somehow biased. It is necessary, therefore, that new resistivity measurements are acquired from a different well to calibrate and improve log water saturation. However, all fresh plugs cut from the newly drilled wells have been damaged and only plugs from a well drilled in 2008 are available. The main objective of this work is to check whether the plugs stored from the well drilled in 2008 are still fit for resistivity measurements (by comparing 2008 CCA data with the newly acquired ones), and if so, perform resistivity measurements at reservoir conditions, derive new Archie parameters and use it to see if log water saturation can be calibrated and/or improved.