Gulf of Suez Reservoir Rocks

Gulf of Suez Reservoir Rocks

Basement reservoirs
Here the porosity is of secondary type, either due to fracturing or to weathering of the basement
Oil productive basement rocks are present in four localities in the Gulf of Suez
1-shoab Ali
2-souht geisum
3-G.S. 304
4-zeit pay fields: it the largest basement reservoir

Paleozoic reservoirs

The Paleozoic sandstone house the bulk of oil of this field
Because of the lack of fossils in the Nubian sandstone, the section is subdivided according to heavy minerals assemblages into
A-upper Nubia ’A’ : This considered cretaceous
B-middle Nubia ‘B’ : which is made up of black shales of carboniferous age
C-lower Nubia ’C’ : which is oil-bearing in
*Ras Budran
*July
*Ramadan
*Sidky

Cretaceous reservoirs

*Nubia’A’: early cretaceous sands are oil-bearing in
*Hurghada
*Ras Gharib
*Bakr
*July
*October
*cenomenian sands: are productive in
*Belayim marine
*October
*turonian sands and limestone: from
*Balayim marine
*Bakr
*Amer
*Ras Gharib
*Kareem
*July
*Ramadan
*early senonian: are oil-bearing in
*July
*Ramadan
*Belayim marine
*October
*Sidky

Eocene reservoirs

They are consist of fractured or cavernous limestone from
*Asl
*Ras Matarma
*Bakr
*West Bakr
*Kareem
*Shoab Ali

Miocene reservoirs

They are the most prolific producer in GOS
They house the bulk of reserves and are present in many fields both on land and offshore
The Miocene reservoir rocks are sandstone
The main oil bearing levels are present in the
*Belayim, Kareem, Rudies, Nukhul formations
1-In Kareem-Rudies formations : as in Morgan, Belayim land Belayim marine, July, Shoab Ali, Ziet pay fields
2-In Belayim formation : as in Belayim land, Belayim marine, Morgan, Shoab Ali fields
3-In Nukhul formation : as in Rudies, Sidri, Shoab Ali G.S 173 fields
*And numbers are present in Zeit-South Gharib sequence

Pliocene-Pleistocene reservoirs
Sediments belonging to Pliocene-Pleistocene have been found in Abu Durba fields




Cap rocks
In GOS sealing beds are abundant especially in the Cretaceous and Miocene
The most effective belong to Miocene. The evaporate beds within Nukhul, Rudies, Belayim, South Gharib, Ziet formations with the oil accumulations of Miocene sequence



Traps

The rifting process which caused the formation of the Gulf of Suez left marked imprint on the tectonic framework and geological history of the province
1*the pure structural traps are rather limited and totally confined to the fields in which the oil is housed in pre-Miocene reservoirs
This is due to pre-Miocene in GOS was characterized by continuous and laterally uniform sedimentation and thus the possibility for lensing and depositional breaks and lateral facies change was minimal

*the pure stratigraphic traps are not very numerous in the GOS due to intense and continuous tectonic movement which the region witnessed after late Eocene times so it is hard to find oil trap in the region which would owe its presence to stratigraphical conditions only with no structural element involved
One field may be excepted, the Gemsa oilfield along the west coast of the GOS near its junction with red sea
Another trap considered to be of the stratigaphic type is Miocene reefal limestone which is present in the eastern flank of Ras Gharib fields
*In contrast, the majority of the oil discoveries in GOS province can be assigned to structural-stratigraphic combination type of trap. This applies to the most of Miocene pools in GOS which display marked lateral change in facies, permeability and depositional breaks, reefal development and irregular evaporitic deposition in addition to the influence of the tectonic movement

Source rocks
The finding indicate that the oil-prone rocks are present at many levels within the geological succession
*potential oil-prone source rocks are Kareem and Rudies formations of the Miocene and the Eocene shale and limestone and late cretaceous carbonates and shale
*possible oil and gas prone source rocks are Belayim formation and Paleocene

Structure
The late Paleogene-early Neogene in Egypt witnessed drastic tectonic activity expressed by widespread regression and transgression together with generation or reactivation of faults and fault-bounded basin such as GOS. Late Paleopgene movement were also accompanied by basaltic extrusion
Tectonic activity in this time was mainly due to the action of stresses, which induced the separation of the Arabian plate from Africa
These stresses extended beyond the late paleogene and belonged to two main phases of activity
The first phase started during the Oligocene or may be during late Eocene and ended by generation of GOS sedimentary basin (taphrogenic depression) in late Oligocene times

This depression became the site of active sedimentation during most of Miocene and early Pliocene times

The second phase of tectonic activity seems to have started in early Miocene. This phase was inaugurated by widespread marine transgression over the shelf area of northern Egypt
During this phase basaltic activity ceased and near the contact langhian/serravallian the regressed from the shelf area of Egypt restricted the conditions of sedimentation leading to deposition of evaporates prevailed in GOS and red sea
During this time the connection of Mediterranean with the gulf was severed (since the serravallian) and the gulf was the site of evaporate sedimentation
The period of tectonic subsiding epirogenic movements, which is associated with the generation of this basin, may be an echo of the Helvetian phase of European geologists and may have occurred at various intervals during the Rupelian (middle Oligocene)