Calibration of Stratigraphic Models in Exploration Settings

David T. Lawrence, Mark Doyle, T. Aigner

A two-dimensional, stratigraphic forward model has been successfully applied and calibrated in clastic, carbonate, and mixed clastic-carbonate regimes. Primary input parameters are subsidence, sea level, volume of clastics, and carbonate growth potential. Program output includes sequence geometries, facies distribution, lithology distribution, chronostratigraphic plots, burial history plots, thermal/maturity history, and crossplots.

Applications to data sets from Main Pass (U.S. Gulf Coast), offshore Sarawak (Malaysia), and Baltimore Canyon (U.S. East Coast) demonstrate that the program can be used to simulate stratigraphy on a basin-wide scale as well as on the scale of individual prospects. The Main Pass section is an offlapping sequence of Miocene-Pleistocene clastics. The model simulates 17 m.y. of geologic history and reproduces gross basin geometry, sequence boundaries, intervals of sediment bypass into deep water, paleobathymetry, shelf margin positions, positions of nearshore marine sands, foreset geometries, and thickness of topsets and bottomsets.

Three Neogene carbonate buildups in central Luconia, offshore Sarawak, were modeled using a sea level history optimized to reproduce the internal facies architecture. The model simulated transgressive buildup, buildout, buildin, and subaerial exposure phases, consistent with seismic and well data. The interactively derived sea level curves used to simulate the buildups and the Haq et al sea level curve have similar timing on 11 or 12 observed lowstands, though magnitudes differ. Stratigraphic forward modeling in areas with simple subsidence histories may be a new method of deriving and testing eustatic sea level curves.

Jurassic to Pleistocene basin and stratigraphic sequence geometries, mixed clastic-carbonate facies distribution, and thermal/maturity history were modeled along a 300-km regional dip line of the Baltimore Canyon Trough. Simulated features of interest include a progradational

Middle Jurassic carbonate margin punctuated by clastic deposition during sea level lowstands and a Late Jurassic-Early Cretaceous aggradational carbonate margin culminating in the development and subsequent drowning of isolated carbonate buildups.

AAPG Search and Discovery Article #91022©1989 AAPG Annual Convention, April 23-26, 1989, San Antonio, Texas.