"Wheeler Diagrams": A Useful Exploration Tool in the Gulf of Mexico
Ramon H. Trevino, L. Frank Brown Jr., Robert G. Loucks, and Ursula Hammes
Bureau of Economic Geology, Jackson School of Geosciences, The University of Texas at Austin, Austin, Texas
One product that resulted from a study of the sequence stratigraphy of the Corpus Christi Bay region is a time-stratigraphic cross section, commonly known as a "Wheeler diagram" (Wheeler, 1958). The cross section portrays time on the y axis (ordinate) and distance on the x axis (abscissa). The Corpus Christi Bay area comprises a series of growth-faulted subbasins that become younger basinward. From our research, we were able to delineate six third-order (~1–3 m.y.) sequences within the Frio Formation. The thickest part of each sequence is the off-shelf low-stand systems tract (i.e., basin-floor fan, slope-fan complex and prograding deltaic wedge). Using available biostratigraphic data, we were able to calibrate and correlate sequence boundaries and maximum flooding surfaces of the Frio third-order sequences to global coastal onlap and cycle charts. In a subsequent study of time-equivalent sections in another part of the Gulf of Mexico basin, we used the Frio time cross section to predict ages of prospective Oligocene off-shelf low-stands, which had minimal paleontologic control. Using our Wheeler diagram and published fault maps in conjunction with the hypothesis that significant shale ridges and growth faults approximate paleo-shelf edges, we could estimate the location, stratigraphy, and age of intraslope subbasins containing highly prospective, off-shelf, lowstand deposits that were basinward from areas of known biostratigraphic and well control. We propose that Wheeler diagrams, in conjunction with sequence stratigraphy, can be useful, predictive exploration tools.
AAPG Search and Discovery Article #90080©2005 GCAGS 55th Annual Convention, New Orleans, Louisiana