The huge original oil in place (OOIP) of heavy oil within the upper Maastrichtian carbonate succession of Tayarat Formation in Kuwait Burgan field lead to paying more attention to its economic value and the necessity of characterizing it at multi-scales for better commercial utilization. However, its high degree of heterogeneity and complexity as a consequence of depositional and diagenetic factors, the presence of fractures in high frequencies, and existence of heavy oil (10 −15° API) with very high viscosity (80,000 cP) and non-movable bitumen in high quantities make the evaluation process very challenging and difficult. This study is aiming at characterizing these carbonate succession using a robust combination between digital and conventional methods.
One hundred seventy-seven (177) feet of representative whole core intervals were imaged by Dual Energy (DE) X-ray CT imaging technique to assess heterogeneity and identify main porosity regions within each core section for representative sample selection. The selected and extracted samples were characterized geologically and petrophysically using MICP analysis, porosity-permeability measurements, micro XCT images and petrographical analysis in order to identify main sedimentary textures and reservoir rock types (RRT), and then generate texture-based poroperm trends. The generated poroperm trends were combined with the DE derived logs in order to generate high-resolution porosity and permeability logs.
The Dual Energy CT imaging provided bulk density and photoelectric factor data that were critical for the determination of porosity and lithological variation along the core lengths. The petrographical analysis revealed common and distinctive geological textures and RRT's within the main lithological groups of the Tayarat Formation. Unique and distinctive texture-based poroperm trends were generated for each lithological group. The derived porosity and permeability logs showed a very good match with the lab-derived porosity and permeability data.
The integrated digital and conventional data at multiple scales were essential in improving our understanding of Tayarat geological and petrophysical properties.