Inversion of dynamical indicators in quantitative basin analysis models. II. Synthetic tests and a case history using dynamical indicator tomography

The dynamical evolution of sediments in basins, and their compaction, is the underpinning keystone on which rests the ability to model thermal history of the basin and hydrocarbon generation, migration, and accumulation histories. A presentation is given of the dynamical tomography method, which inverts dynamical indicators to evaluate the parameters in a 1-D fluid-flow/compaction model, including values dealing with geological events as well as values dealing with intrinsic, or assumed, lithologic equations of state. Synthetic tests illustrate the operation of the system. Using observed downhole quantities: total depth, formation thicknesses, variation of porosity, permeability, and total fluid pressure with depth from the Navarin Basin COST No. 1 well, Bering Sea, Alaska, the numerical algorithm was tested and found to be effective in a nonlinear inverse sense to determine and/or constrain the parameters entering quantitative models of dynamical sedimentary evolution. The predictions of present day total depth, formation thicknesses, porosity, permeability, and fluid pressure with depth are close to the measured data. The minimization provides the uncertainty in each parameter and so the geohistory of a well can be defined better.