Sedimentary Formations in Al'Daww Depression has been determined on fossils or strata correlation on upcent of fossils.
We found from geological data processing and analysis of litho logical series to Al'Daww Depression that the important rocks th
at generated oil and gas are belong to Silurian and lower Triassic where as Jurassic sediment does not represent any important, nor upper Cretaceous sediments because its adjacent to surface and invaded by surface water.
Reservoir rocks represented by Markada's Kurashina Dolomite, Butma, Rutba and Judea formations.
The good cover rocks represented by the Tanf, Amanous Shale and Kurrachina Anhydrite 13
as well as the upcent of some cover formations deteriorated the important of some reservoir formations at Al'Daww Depression This study reveal that the subsiding velocity rate to the basin produced the thickness' and made this formations more prospective in general.
All the well logging reinterpretation by using the new softwares, cores
analysis and results of seismic 2D and 3D surveys allowed to identify the
reservoir characteristics of Kurachina Dolomite Formation of middle Triassic,
for two zones (C2, D1)
in Jihar field and its affect on hydrocarbon potential in
this area.
It's found that C2 reservoir consist mostly of dolomite and small amount of
shale and anhydrite, fractured and all the fractures are full of organic
materials, calcite, anhydrite, silica and little amount of stilolite, while there is
succession of limestone and fossil remains, in some places there is shally
dolomite. Whereas D1 reservoir is mostly crystalline limestone and the
fractures filled with dolomite.
This research aims to study the sedimentary and palaeogeographic
evolution of the Kurachina Dolomite Formation along Palmyrian belt zone.
Studying this formation in its Northern and Southern parts has shown that it
consists of two lithostratigraph
ic members, where each of them includes a
series of lithological units. The petrological study of the components of these
units shows that they are composed of four distinguished facies: Dolomitic
limestones, clayey limestones, clays and anhydrites, pure or mixed, and
deposited in repeated harmonic layers, gathered mostly in neutral sedimentary
sequences. Dolomitic limestones are the most common and important facies,
they are composed of micrite muds which have been subjected, in different
degrees to synsedimentary or late dolomitisation processes through pumping or
burial mechanisms. Dolomitisation intensity decreases downward the formation
and increases laterally from the south to the north of the Palmyrian chain.
