Determination of Flow Zone Units for Diverse Geological Environments and Facie: Study of Carman-Kozeny Compliant and Non-compliant Formations and Related Overburden Analysis
Nguyen Chu, Dat and Truong, Nhan Bao
Engineering Honours Degree, 2013
University of Adelaide
Reservoir simulation relies on an accurate and consistent description of reservoir parameters, in particular optimal vertical zonation of formation intervals. The Carman-Kozeny (C-K) equation and theory (Amaefule et al. 1993) has been used for this purpose for a number of years. However, as the C-K theory works on the premise that a geological unit is reasonably well sorted in terms of grain/ pore throat size, there are instances where the theory cannot be directly applied and alternative handling of such intervals may be thought. Furthermore, in order to use this methodology, ambient core data needs to be converted to overburden conditions and this aspect has not been well documented in the literature.
The research described here involves the application of the C-K formulation to identify both, compliant and non-compliant cases and to classify both groups in terms of the underlying causes for such differences, generally linked to grain size and sorting. Furthermore, the research also points out how analyses can be improved under a modified C-K framework by introducing the lithology factor and cementation exponent to the C-K equation (Nooruddin et al. 2011). Data used was from Australian and Papua New Guinea fields. For cases studied, the results show that the C-K theory is applicable only for well sorted and fine grained intervals (i.e. upper shoreface) and the modified method is able to improve non-compliant C-K intervals as observed for the zones in Bayu-Undan field. The second part of the study involved the derivation of suitable relationships between ambient and overburden core parameters, porosity and permeability, and it has been shown how such relationships influence the C-K analysis outcomes. Transforms for changing ambient to overburden conditions for C-K compliant cases were specifically formulised. Such formulations were subsequently tested with field data from offshore Australia, PNG and deepwater Gulf of Mexico (GOM). It is shown that transformation to overburden condition can change the C-K compliance in certain cases; however, the effect is small. The link to rock compressibility was also briefly studied; however further research and data are needed to fully develop general relationships.