A New Correlation for the Cementation Factor in Low-Porosity Carbonates

Summary The use of common correlations for the cementation factor, m, has led to discrepancies between log interpretation and actual test results in several tight carbonate formations offshore Abu Dhabi. While logs indicate high water saturations, production tests resulted in unexpected dry hydrocarbons. The existing common correlations for carbonates yield constant m (Archie) or an increasing m with a decrease in porosity (Shell formula). In the carbonates found offshore Abu Dhabi, m decreases with decreasing porosity. Based on core and log data from five formations in 14 structures, a more representative correlation for m has been derived. This new correlation successfully eliminates the discrepancies between log and test results. Examples confirming the validity of the new formula are included.