Rock-Typing in Carbonates: Getting Out of the Maze

François Umbhauer*, Gerald Hamon, Michel Rebelle, Catherine Javaux, and Cécile Pabian-Goyheneche
Total, France
*[email protected]

Rock-typing in carbonates is a challenging task requiring the coordination of key factors: (1) effective project management; (2) detailed knowledge of the reservoir geology from regional to pore scale; and (3) a consistent well data set. This presentation reviews the rock-typing approaches used in Total for the past 35 years and evaluates them in terms of accuracy (capacity to represent the petrophysics and its variation in the reservoir) and efficiency (ability to be easily managed while allowing a good history matching and reserve prediction). Best practices are pointed out, depending on the reservoir complexity, dataset quality and reservoir study objectives. To ensure a successful rock-typing in carbonates several aspects should be considered: (1) the pore network should be characterized at micrometric scale, (2) links between petrophysical laws and geology should be established as soon as possible; (3) the propagation of rock-types between wells should honour the sedimentological model including diagenesis distribution; and (4) rock-types could be propagated on a log-response basis, even when supported by micrometric features (CT scan textural analysis). The transition from static to dynamic rock-typing is another important issue. Flow units (homogeneous Krow-Pcow) are not only related to static rock-types. Wettability can significantly vary within the same reservoir according to structural position and permeability. In carbonate reservoirs, an efficient rock-typing should not follow any golden rule but rather a pertinent workflow that is adapted to the data set quality. Integration of geological and petrophysical data, use of a geological driver at micrometric scale and implementation of new techniques should efficiently improve the rock-typing studies.

AAPG Search and Discovery Article #90077©2008 GEO 2008 Middle East Conference and Exhibition, Manama, Bahrain