Diagenetic impact on traps
|Exploring for Oil and Gas Traps
|Treatise in Petroleum Geology
|Predicting the occurrence of oil and gas traps
|Exploring for stratigraphic traps
|John C. Dolson, Mike S. Bahorich, Rick C. Tobin, Edward A. Beaumont, Louis J. Terlikoski, Michael L. Hendricks
Stratigraphic trap geometries can be mapped and defined at any geologic scale from an interpretation of facies in seismic or well data (see Basic open hole tools and Basic cased hole tools), but diagenetic overprints often modify primary trapping geometries. Diagenetic changes often can be predicted and mapped reliably, especially if they follow facies or paleostructure. However, if diagenesis does not follow facies or paleostructure, then the exploration and exploitation risk increases because predicting the trap location is more difficult.
Access to cores, samples, and modern wireline log suites greatly facilitates subsurface interpretation. In Figure 1, both lateral and top seals in the dolomite reservoir were created by anhydrite cementation during early diagenesis. Primary facies changes do not control the location of the trap.