Sedimentary facies analysis, seismic interpretation, and reservoir rock typing of the syn-rift Middle Jurassic reservoirs in Meleiha concession, north Western Desert, Egypt

The Middle Jurassic syn-rift sediments of the Khatatba Formation contain not only the principle source rock organofacies in the north Western Desert (NWD), but also several potential sandstone reservoir targets. However, controls on the reservoir quality of the Khatatba facies and spatiotemporal evolution of the reservoir rock types (RRTs) are still blurred. This study integrates seismic, wireline logs, and conventional core data from some wells in the Meleiha development lease in the NWD to investigate the petrophysical characteristics of the Khatatba reservoir facies, and determine the different RRTs. On seismic, Khatatba Formation consists of high reflectivity, continuous reflections displaying an upward decrease in seismic amplitude corresponding to a fining-upward clastic succession of fluvial-tidal facies. These facies display a large-scale pore system heterogeneity, thereby comprising three different RRTs. RRTI and RRTII rocks have a well-connected pore network dominated by capillary and super-capillary pores (> 10 & mu;m), whereas sub-capillary pores (< 10 & mu;m) are more common in RRTIII sediments. RRTI rocks consist of quartzose sandstones with a clean pore network (cement < 20%). The open pore system of RRTI allows a displacement of more than 80% of the pore water at entry pressure levels < 500 psi. Carbonate and clay components are more common in RRTIII rocks (average = 5.6% and 13%, respectively). These components adversely impact the pore system connectivity of RRTIII sediments. Fluvial channel sandstones host the principal fluid flow conduits where RRTI sandstones account for more than 95% of the reservoir flow capacity. The present study provides the first reservoir rock typing for the Khatatba clastic reservoir facies and highlights the link between depositional, compositional attributes and the spatial distribution of the different RRTs.

Automated summary

This study investigates the petrophysical characteristics of the Khatatba reservoir facies and determines the different reservoir rock types (RRTs) using seismic, wireline logs, and conventional core data. The results show that the Khatatba Formation consists of three different RRTs, with RRTI having a well-connected pore network and RRTIII containing more carbonate and clay components that affect the pore system connectivity. The study highlights the link between depositional, compositional attributes and the spatial distribution of the different RRTs, providing important insights into the geological properties and spatial distribution of the Khatatba reservoir.