Reservoir architecture of the Gharif Formation outcrops in the Southern Huqf area, Sultanate of Oman

Abstract

The Gharif Formation was deposited in the early Permian and is one of the major producing oil and gas reservoirs in the Sultanate of Oman. The Upper Gharif Unit crops out at Wadi Gharif, where a detailed outcrop characterization was undertaken. Fluvial channel sandstones, inclined heterolithic stratification (IHS) and floodplain palaeosols are the dominant facies associations. Deposition was in a low to moderate sinuosity multistorey fluvial channel belt with fluctuating water levels, allowing water retention in the channel while mud deposited on the upper portions of the point bar was exposed. Sandstone-body geometries indicate ribbon-like channels flowing in a NW orientation. The channel belt is estimated to be between 150 and 250 m wide and encased in oxidized red palaeosols. The depositional units are stacked from east to west and the scour and erosional surfaces are indicative of cut and fill under relatively low accommodation conditions. The reservoir architecture highlights the presence of potential claystone baffles in the IHS section on the margins of the point bars. Differences in grain size between the coarse-grained channel sandstones and the fine-grained IHS sandstones potentially create a permeability contrast while the inclined surfaces will affect fluid movement for both vertical and lateral flow. A deterministic surface-based model was constructed to access static connectivity of the Gharif fluvial channels.

Systematically variable geometry and architecture of incised‐valley fills controlled by orbital forcing: A conceptual model from the Pennsylvanian Breathitt Group (Kentucky,USA)

“…), comprising almost the complete Pikeville Formation. Basal erosional boundaries for modelled IVF were generated applying a deterministic approach to stratigraphic markers (coal beds, in this case) to create high‐resolution surfaces from which incised valleys were carved out through user input of isochore lines during the process of defining the shape and geometry of sedimentary bodies (Howell et al ., ; Alsop et al ., ). Facies modelling of the volumes created for marine members, stratigraphically defined by coal beds and by the infill of incised valleys, was performed using a vertical trend function of facies associations from well data and on horizontal variations between individual wells.…”

Seismic-driven geocellular modeling of fluvial meander-belt reservoirs using a rule-based method

“…Other mudstone beds occurring throughout the barform are instead thought to drape accretion surfaces that record the migration of the bar front; mudstone units of this type are generally referred to as 'mud drapes' hereafter (cf. McGowen & Gardner 1970;Hartkamp Bakker & Donselaar 1993;Pranter et al 2007;Alsop et al 2014;Biber et al 2017). Bar-front muds or mud-rich packages might represent different types of deposit with varying characters and genetic significance, some of which might be below the log resolution and are therefore not considered here.…”

The application of outcrop analogues in geological modelling: a review, present status and future outlook

“…The papers cover a range of clastic depositional environments from fluvial (Alsop et al 2013;Pranter et al 2013;Rittersbacher et al 2013;Keogh et al 2014;Nordahl et al 2014) through paralic (Massey et al 2013;Rarity et al 2013) to deep marine (Eschard et al 2013). Two deal with LiDAR and virtual outcrop techniques from a ground base (Rarity et al 2013) and from a helicopter platform (Rittersbacher et al 2013); ground-based LiDAR was also used by Keogh et al (2014).…”

“…Alsop et al (2013) and Pranter et al (2013) document studies in which the actual reservoir interval crops out near the oil fields. This situation provides the most robust match between the analogue and the modelled interval but such ideal cases rarely happen.…”