Shiranish formation in Sazaba Oil fields region had been divided by
Petrology study and well Logs measurements to three major members (lower –
middle – upper). Then these members have been divided to lithostratigraphic
units and subunits. This stu
dy showed that the lower member is formed of
clayey - limestone rocks rich in planktonic foraminifera and glaconitic sand.
The middle member consists of organic limestone facies, dolomitic-limestone,
sometimes clayey - limestone rocks with crystals of pyrite and glaconitic sand.
Organic- limestone rocks and detrital limestone are predominant in the upper
member interbeded by dolomitic-limestone and rare clayey – limestone. This
facies contains pelagic and planktonic foraminifera.
The role of diagenes phenomenon is evident on Shiranish’s facies through:
dolomitization according to burial and miksing processes. It is also clear
through chemical compaction, mechanical compaction, cemenation,
micretisation and silisification.
The authors’ works concern the sediments of the upper part of Tortonian
within the basin of El Ma Labiad located at the southern part of Tebessa city,
belonging to the eastern saharian Atlas mountains chain on the Algero-
Tunisian borders.
The se
dimentological analysis, carried out on 120 samples, has confirmed a
downlap development structures towards the West of the basin. These analyses
have also proved the presence of a detrital continental sedimentation of four
environments characterized by the river, delta, lake and marsh materials.
The petrographic and morphological analysis reveal a clastic sediments
essentially quartz-bearing interbedded by some argillaceous intercalations, and
a far-off water transport of an origin probably saharian.
Al Rutba Formation , bellowing to the upper Cretaceous, is one the
main formation of the stratigraphical coumn of Euphrate Depression.
It is importance becomes from that it can statute the principle
petroleum reservoir in high member of the depres
sion fields.
Producing oil and the natural gas.
The importance of this group is to be the main reservoir of oil in
various fields of low oil producing natural gas. The present study is
based on subsurface geological data, presented by cores, well logs and
chemical results of the analyses laboratory.
