ICE 2022


The Jurassic Marrat Formation, of West Kuwait Abduliyah and Dharif (AB-DF) fields, hosts an underexplored carbonate reservoir with limited aquifer support and fast pressure depletion, being currently close to bubble point pressure conditions. An integrated reservoir description becomes critical to produce an effective development plan. Building a unified high-resolution stratigraphic model, fully consistent with neighboring mature analog fields from West and North Kuwait, has for the first time been utilized to link AB and DF fields; thereby getting rid of all inconsistencies associated to legacy soloed stratigraphic frameworks. A unified high-resolution stratigraphy framework has been established and correlated along >40 km of dip-oriented cross section. An optimized display of raw and processed logs, core descriptions of lithology and depositional environments were instrumental to resolve the chronostratigraphic well correlations across the two fields. Reservoir rock types (RRTs) enabled optimal characterization of the reservoir at both field and plug scale. A rock physics based analysis allowed to transform the P-Impedance volume into three porosity sub-volumes, outlining thereby the tight, intermediate and good quality depo-facies; in turn hierarchically used as containers to condition a geostatistical spatial distribution of the seven log-based RRTs, all constrained to a pre-established gross depositional and diagenetic model. The south-north basinward migration of highstand and lowstand prograding wedges outlined most of the downdip reservoir quality development. Sequence stratigraphic correlation and isochore mapping of parasequences allowed to decipher the ramp evolution and the identification of mud-prone low sinuosity incision features, cutting downslope at ramp margins. These incisions have been identified for the first time ever in West Kuwait, with relief in excess of 100ft and 300-500m width. Moreover, enhanced resolution from deterministic and simultaneous seismic inversion enabled to refine their 3D extent, being intimately associated with amplitude anomalies. A revamped regional static model, enabled a much improved lateral continuity, hence an effective change in the reservoir layering methodology. Specifically, baffles and matrix thief zones were all implemented, making a key improvement for connecting the different reservoir hydraulic units in the correct way; and enabling the dynamic model to reproduce the actual depletion patterns.