Fracture characterization and modeling of unconventional Najmah-Sargelu reservoirs of Umm Gudair Field, West Kuwait. 9th Middle East Geosciences Conference, GEO 2010.

The Najmah-Sargelu unconventional naturally fractured carbonate reservoirs are spread across many fields in West Kuwait, some of which, such as Umm Gudair are on production for the last 25 years. Natural fractures have a significant impact on the reservoir performance as they affect well productivity. Therefore, understanding their significance through fracture characterization is helpful in well placement and field development. This presentation shows an overview of the efforts to build a 3-D stochastic fracture model for reservoir characterization in the Umm Gudair Field. The model is generated in FracaFlow© through the analysis and integration of well data like cores (including oriented core), borehole images (BHI), well-logs, mud losses, production logging and well test data along with 3-D Q-Seismic data through structural, seismic attribute and seismic facies analyses. The impact of lithology on fracture occurrence was quantified based on rock-typing and distributed using a high-resolution, sequence-stratigraphic framework. Rock types are a real 3-D fracture driver and provide a reliable means of adjusting the density of diffuse fracture in the Najmah-Sargelu reservoirs of Umm Gudair Field. Three sets of diffuse fractures were identified from borehole image data: N20°E, EW and N170°E. Large-scale fracture corridors including sub-seismic faults, identified from seismic analysis were calibrated with core and BHI fractures through fracture data analysis workflows. The model finally incorporates two scales of tectonic fractures: diffuse fractures and large-scale fractures that have a direct bearing on well and field production behavior. The fracture calibration was performed using the dynamic data set such as production log and well wise production data. Synthetic well tests were simulated and matched with the real build-up data at wells. These data were then used to propagate 3-D fracture properties (fracture porosity, fracture permeability and equivalent block size) for constructing a reservoir simulation model.