Full Pore System Petrophysical Characterization Technology for Complex Carbonates - Results from Saudi Arabia
We present results of new petrophysical characterization technologies for complex carbonates using petrophysical rock types (PRT). Our PRTs are derived from Thomeer analyses of up to 1,500 mercury injection capillary pressure (MICP) curves. Thomeer analysis involves the fitting of the Thomeer hyperbola to core plug MICP data by determining the Thomeer parameters (initial displacement pressure, geometric factor, and bulk volume mercury injected). This results in a full characterization of the entire pore space of each core plug. This is particularly important in complex carbonates where multimodal carbonate pore systems are prevalent and reservoirs have large hydrocarbon column heights and areal extents.
Our Thomeer parameter databases can be manipulated to extract PRTs, correlations and statistics for each reservoir. Clerke has defined PRTs as objects in the three dimensional space of Thomeer parameters. One technique called “Map Inversion Rock Typing” (MIRT) exploits the ordered distribution of PRT’s on a two dimensional (porosity-permeability) petrophysical map. PRT information is obtained by querying this petrophysical map using core-calibrated well-log predictions of porosity and permeability. The query returns PRT classification probabilities with associated Thomeer parameters for each well level. These organized realizations of pore system data are used within a stratigraphic framework to distribute throughout the reservoir model. The realizations are readily used as input to calculate saturation-height behavior.
Saturation-height results are compared to validation data: oil-based mud core saturations and well log saturations. The oil-based mud core saturations confirm the validity of the saturation model and the necessity for the inclusion of multiple pore systems. Our result comparisons are shown at two levels: the saturation-height model at the well level and deployed at the 3D model level and then projected to the well location. Our saturation-height calculations utilize the fully upscaled Buiting-Thomeer functions recently developed . Our technology results are also compared to previous J function field models. Results from this saturation-height method are compared to validation data and exceed previous industry results.
AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009