Stratigraphic well correlations for 3-D static modeling of carbonate reservoirs

The principles and purposes of stratigraphic well correlation in carbonate sedimentary systems are defined and discussed within the context of static reservoir modeling. The challenge of well correlations is to relate the heterogeneities measured at core and well scales to the spatial heterogeneities at reservoir and flow unit scales. The introduction of a priori knowledge in the process of stratigraphic well correlation is critical to support the stratigraphic rules and to establish a coherent geological and petrophysical concept. The links between well correlation and geostatistics are discussed with regard to the stationarity hypothesis and property trend analysis. We stress that wells are incomplete and biased samples of the geological reality, which is not dependent, unlike the dynamic reservoir behavior, on the well numbers, location, and spacing. Stratigraphic rules are applied as a function of the well spacing relative to the geological reality. A simple trigonometric method, combining angle of base profile, paleobathymetry, and well spacing, is introduced to check the validity of the well correlation in carbonate ramp-like systems. Two models, based respectively on outcrop and subsurface with seismic data, are discussed in detail to show the combined influence of the data set, sedimentary systems, and diagenetic transformations on stratigraphic well correlations.