Madatov A.G., Doyle E.F. Effective Basin Models in the Simulation and Prediction of Abnormal Pore Pressure

2013. — 512 p.
An Effective Basin Model concept is introduced as a well-balanced combination of classical engineering and basin modeling approaches to the problem of pore pressure prediction before and during drilling. Both approach and relevant Earth models are reviewed and systematized in the context of their practical applicability and consistency to the theory of real data inversion. Special attention is paid to the applicability of seismic data for this purpose, and its inherent advantages and limitations are analyzed. The correct combination of seismic methods with basin modeling is discussed. A composite 3D overpressure modeling operator is introduced and considered in detail regarding its accuracy/stability and invertibility against real data. The operator can account for the main overpressuring mechanisms including 3D pressure communication mechanisms - centroid effect, dipping aquifer beds, pressure drop across sealing faults, etc.). Extensions of numerical routines in the form of user-defined burial and thermal histories are described. These extensions allow for effective pore pressure simulation for realistic geology settings, including stratigraphic unconformity, complex faults, and salt tectonics. The specifications for a relevant effective basin model are described in detail. Computer simulations of pore pressure evolution in the basin time scale are illustrated and analyzed against theoretical and real data examples. The data inversion theory is adopted for multi-well log data inversion into a pressure model parameter space. Different kinds of solutions for the relevant inverse problem are analyzed. The common approach implies an inversion of porosity/pore pressure data sets attached to the calibration well positions within the range of the established and upscaled in advance, effective basin model. Global and local optimization strategies are reviewed in this connection. Their proper combination adjusted for the purpose is introduced and the relevant computer algorithms are described in step-by-step form. The practical implementation of the Effective Basin Model concept for pore pressure prediction before and during drilling is illustrated by real data cases from different sedimentary basins worldwide.