Capillary Pressure - An Integrated Flow Chart for Carbonate Reservoir Characterization from Resource Assessment to Field Development and EOR Applications

Aiming to improve the characterization of Carbonate Reservoirs from resource assessment to optimization of the static and dynamic modeling, we describe a holistic flowchart for an integrated approach by using the capillary pressure measurements. Its most innovative steps from pore scale to field scale is illustrated on a Super Giant Carbonate Reservoir from the Middle East. The flowchart relies on patented, published and proven "data driven" algorithmic techniques (k-NN, Histogram Upscaling and MRGC-CFSOM clustering) devoid of any user’s bias. Its capability to integrate Static and Dynamic, from Pore Scale to Log scale, stems from the integration, prediction and upscaling at log scale, over cored and un-cored intervals of MICP curves together with all core and log material. Predictions by means of "k-NN multiple modeling" of SCAL & RCA plug measurements allows a reliable and accurate characterization of the rock matrix at log scale, while quantifying its degree of heterogeneity. By revealing to the geoscientists, the pore scale rock texture, its stratigraphic evolution and its heterogeneities, the continuous profile of upscaled Pore Size Distribution (PSD) curves vs logs provides invaluable information on the rock forming processes controlling the matrix Porous Network. By applying the Purcell theory onto the upscaled PSD, the "Log scale" Permeability and the true FZI and Rmh are computed which are then used as input to a e-Facies model (MRGC-CFSOM) by integrating to other logs and core material. The e-Facies model is interpreted in terms of "matrix" storage and flow parameters as well as in terms of depositional mechanisms and diagenetic overprints, in the light of the core descriptions whose Petrophysical pertinence is thoroughly and quantitatively validated with all the Petrophysical material. By reversing the method used to derive PSD from MICP saturation curves and using the Pc equating the buoyancy forces at any depth increment, the saturation at any depth increment above the actual Free Water Level (or a scenario of FWL), is computed from the continuous profile of upscaled PSD. Production data, RSTs and PLTS provide the information on total flow and by subtracting matrix contribution to the total flow, the location and quantification of the contribution of the depth intervals with large vugs and fractures is greatly eased, particularly if Borehole imagery is available. The contribution of Matrix, large vugs and fractures are then merged into a single model used for robust well to well correlations, zonation of the reservoir, 3D gridding and volumetric evaluation. Using this innovative flowchart approach, characterization of high permeability streaks, saturation height function and chemical polymer EOR processes were greatly improved as input to the static and dynamic model history match exercise.