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AAPG GEO 2010 Middle East
Geoscience Conference & Exhibition
Innovative Geoscience Solutions – Meeting Hydrocarbon Demand in Changing Times
March 7-10, 2010 – Manama, Bahrain

Prediction of Reservoir and Seal Capacity for Exploring Jurassic Carbonate Stratigraphic Traps, Northern Saudi Arabia

David Z. Tang1; Philippe Rabiller2; Arthur E. Gregory1; Paul Lawrence1; Abdel Fattah M. Bakhiet1

(1) Exploration Resource Assessment, Saudi Aramco, Dhahran, Saudi Arabia.

(2) Rabiller Geo-Consulting, Pau, France.

The exploration for stratigraphic traps, especially in carbonates, is challenging and requires carefully detailed analysis of petroleum system elements. Accurately defining the spatial and temporal distribution of source rock, reservoir, and seal facies is essential for exploring stratigraphic traps. This study presents an integrated approach for evaluating reservoir and seal capacity of Jurassic carbonates to explore stratigraphic traps using the Facimage electrofacies prediction and calibrated seismic facies modeling techniques.

Core-based rock types were generated for selected Jurassic carbonate reservoir formations by integrating core descriptions, thin-section petrographic data, core plug porosity/permeability, and capillary pressure (MICP) measurements. Reservoir quality and sealing capacity were thoroughly evaluated using core-derived pore-throat size and capillary pressure data from a full spectrum of reservoir and sealing facies. This was followed by calibration of core-derived reservoir and seal facies to well-log responses by constructing Facimage models for selected “Reference Wells” that are extensively cored and analyzed. The Facimage models were rigorously tested by validating predicted electrofacies/capillarity and core-derived rock types, and their sealing capacity. The optimized Facimage model was used to predict electrofacies that represent rock types of varying reservoir quality and seal capacity for all the selected “Application Wells” within the area of interest. The derived electrofacies (rock types) of reservoirs and seals can be upscaled to a seismically detectable level. The upscaled facies were then output as numerical codes into the calibrated seismic facies modeling of 3D seismic volumes using state-of-the-art technologies for analysis, integration, and visualization.

The calibrated seismic facies, rock types and porosity models provide lateral and vertical facies changes of reservoirs and seals within 3D volumes. These are critical elements for exploring stratigraphic traps. The Middle and Upper Jurassic reservoirs have been taken as examples for the above approach. Preliminary results have demonstrated that existing stratigraphic trap analogue and potential new stratigraphic traps can be successfully predicted, as shown in the Upper Fadhili and Arab-D reservoirs.