Cementation Exponents in Middle Eastern Carbonate Reservoirs

TLDR: In this paper, a study of the relationship between variable m values measured on core plugs and detailed carbonate rock types is presented, and the authors conclude that high m values are often representative for specific rock types and that these values should not be rejected but applied selectively in log analysis over those intervals where these rock types occur.

Abstract: The cementation exponent, m, is a major factor of uncertainty in the calculation of hydrocarbon/water saturation in heterogeneous carbonate reservoirs. Hydrocarbon saturations as high as 70 or 80% calculated with the conventional value m=2, may disappear completely with m values of 3 and 4, which are quite common in carbonate rocks. Laboratory data obtained in heterogeneous carbonate reservoirs often show a wide scatter. Constant (average) m values are usually used in spite of such scatter, and data points with m values much higher than the average value are often rejected to obtain straight-line trends. This paper presents the results of a study of the relationship between variable m values measured on core plugs and detailed carbonate rock types. The scatter in the data is analyzed in terms of rock type. The authors conclude that the high m values are often representative for specific rock types and that these values should not be rejected but applied selectively in log analysis over those intervals where these rock types occur.