Dissolution processes, hydrology, void dimensions, and architecture are useful in understanding karsted rocks that serve as reservoirs for oil and natural gas. Three-dimensional cave surveys can be used to assign properties to “karst” cells in geocellular models. Surveys of long karst passages (e.g., Yucatan flooded caves) can be used to infer connectivity (i.e. how many “karst” cells can be neighbors?).

Karst processes ranging from surface weathering to deep burial dissolution have affected numerous karsted intervals that host petroleum accumulations. Recognition and prediction of subsurface paleokarst from seismic or borehole information and prediction of potential petroleum production involves addressing the following questions:

• Does the layer in question consist primarily of carbonate rocks?

Unnumbered Figure

Unnumbered Figure

End_Page29---------------

• Is there evidence to suggest subaerial exposure of the carbonates?

• Can a humid paleoclimate be documented?

• What was the paleo-relief?

• Does the tectonic history include episodes of jointing, faulting, or fracturing that would focus flowing water in the paleohydrologic setting?

• Is there reason to suspect burial dissolution?

• Did karst dissolution pre-date petroleum migration?

• What differences would karsting make to wellbore deliverability, well spacing, drilling operations, injection strategies, and production profiles?

Analogs and regional studies incorporating the elements of these questions can be used in the exploration and production workflow to identify potential problems and opportunities, to constrain geo-model input, and to improve communication of subsurface risks and uncertainties.

End_of_Record - Last_Page 31---------------