This study integrated seismic data, well logs, and core data to analyze the depositional patterns of the Middle Jurassic Khatatba Formation in Egypt and how this impacts the distribution and quality of reservoir facies. The Khatatba Formation comprises two units deposited during distinct rift phases, with nine facies associations identified. The distribution of these facies was governed by variations in fault offset and sediment supply over time. Progradational deltaic facies provided the best reservoir quality overall, accounting for 85% of reservoir flow, while retrogradational distal facies deposited during high subsidence periods had lower quality.

1. The Middle Jurassic syn-rift sediments (Khatatba Formation) of the Western
Desert, Egypt hosting potential reservoir intervals are prospective targets for
hydrocarbon exploration and development campaigns. However, their
depositional evolution and factors controlling distribution of the best reservoir
faces are not very well-constrained.
This work integrates seismic, well logs and conventional core dataset in order to
define the syn-rift sedimentary patterns and their impact on distribution and
quality of the reservoir facies.
Khatatba Formation comprises two discrete units; the lower unit constitutes
lower progradational and upper retrogradational sedimentary packages that are
interpreted in terms of discrete rift phases.
Nine sedimentary facies associations (FA) were recognized and their stacking
patterns are governed by the rift evolution and the interplay between variation in
fault offsets and sediment supply.
Distal sand bar sandstones, marine shales and organic-rich shales were
accumulated during periods of high subsidence.
Successive alternation between shallow and deep facies at the base of the lower
unit reveals repeated short periods of progradation and retrogradation with an
overall progradational trend reflecting an elevated rate of sediment supply.
Episodic fault-controlled retrogradation and progradation continued during the
deposition of the Khatatba upper unit where the progradational deltaic facies
changes upward into retrogradational marine sediments and aggradational-
progradational aeolian and shoreface sandstones.
Five hydraulic flow units (HFUs) were identified and their distribution is mostly
controlled by the rift evolution.
The lowest reservoir quality HFU4 and HFU5 are often associated with the
retrograding distal facies accumulated during highest rates of subsidence.
These zones do not contribute to more than 10% of the reservoir flow capacity.
On the other hand, the progradational deltaic facies accounts for approximately
85% of the reservoir flow capacity in both lower and upper Khatatba units.