North Algeria domain
The Chelif basin is known by the Tliouanet and Aïn Zeft deposits, but also by the number of surface and sub-surface showings that it conceals all along its northern and southern borders. The oil plays are located in the Miocene and the Cretaceous.
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Intervals
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Observations
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Source Rocks
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In the Upper Cretaceous,
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TOC contents vary from 0.5% to 3.23%,
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In the lower Miocene
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The TOC shows values ranging from 0.45 to 1.3%,
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In the Upper Miocene (Messinian)
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The TOC contents vary between 0.5% and 4%.
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Reservoir
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superior Miocene sandstones
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Revealed to be productive (30,000 t of light oil, d = 0.8 g / cm3) in the fields of M’sila and Médjilla (Tliouanet).
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Lower Miocene base sandstones
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The reservoir rock is of paralytic origin and the porosities oscillate between 10 and 15%. These are clay thin sandstones, mainly interposed in the blue miocene blue marls and where one-time porosity values of the order of 20% are observed and an average of 15%. A matrix permeability is noticeable.
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Cover
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The reservoirs can be covered by the clay layers of the Miocene (marl and gypsum) and the Upper Cretaceous (clays and marls).
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Traps
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They are essentially mixed traps (fault, bevels).
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Exploration of the basin uncovered a small oil field “Oued Gueterini” in the Paleogene, which has produced some 3000 m3 / year of light oil since the 1940s; as well as the presence of heavy oil in the M’sila basin.
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Intervals
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Observations
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Source Rocks
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The Upper Albian (Vraconian)
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Geochemical analyzes on the Vraconian of some wells showed an average TOC of 1.4%, associated with a type III kerogen and a tendency to gas.
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The Cenomanian
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Geochemical analyzes show TOC values varying from 0.64 to 2.3%, subject to oil.
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The Turonian
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With an average TOC of 1.6%, the biomarker analyzes indicate a Kerogen type II, with a tendency to oil.
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The Eocene and Paleocene
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They show good Source Rocks potential with an average well TOC of 3.1% with type II kerogen in the oil phase.
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Reservoir
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The Sandstone Albian
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It has an average porosity of 15% and the measured permeability is 1 darcy. The presence of hydrocarbons in this interval has been indicated by logging evaluations which show oil saturation values varying between 20 and 60%.
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Upper Cenomanian - Lower Turonian
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It corresponds to high energy carbonate facies where the petrophysical characteristics show variations according to their positions within the basin itself; the best characteristics are located in the eastern part of Hodna where the Sonic porosity has an average of 16%, as for the matrix permeability it goes from 0.01 to 1.2 mD, where the fracture permeability is close to 1 Darcy.
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The Eocene
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This interval showed hydrocarbon impregnations encountered during drilling, where the porosity is on average 5% and the matrix permeability less than 0.1mD, unlike the fracture permeability which reaches 145 mD.
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Cover
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In the region, the cover is provided by clay or marly series; signaling, however, the development of evaporite series in the M’sila region in the Cenomanian and upper Lutetian.
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Traps
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Mainly mixed traps (bevels and counter faults)
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The genesis and the expulsion of hydrocarbons are clearly argued by the numerous surface and subsurface indices in the Ain Regada-Guelma region;
The main discoveries in this basin are oil, and were made in the Upper Cretaceous of Djebel Onk (1956) and Ras Toumb (1977); as well as in Guerguitt El-Kihal North and Guerguitt El-Kihal South; where oil discoveries were made in 1988 and 1994, respectively; and more recently (in 2001) in Hassi el Kerma.
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Intervals
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Observations
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Source Rocks
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Vraconian
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In the southern part of Constantine geochemical analyzes show that it could be a source of food in the region, with an average TOC of 1.5% and maturity in the oil phase
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Cenomanian
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TOC> 2% and a HIo 400mg HC / g TOC, in the oil window.
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Turonian
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Shows an average TOC of 1.5% with HIo varying from 200 to 400 mgHC / gTOC, in the oil window.
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Santonian and Coniacian
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With a TOC reaching 4.5%, and an average of 2.6%, these show a good potential source rock with mixed Kerogen II / III and a level of maturity in the oil window.
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Reservoir
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Numidian sandstones: having produced in some boreholes drilled in the region of Ain Regada.
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Ypresian carbonates
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Upper Albian carbonates
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The Aptian sub-reef limestones
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Cover
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- The thick clay-marly series that cover the limestone reservoirs of the Coniacian.
- The marly and anhydritic series of the Upper Turonian - The clayey series of the Cenomanian-Vraconian |
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Traps
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Due to the structure of the region, several types of trap may exist; structural to mixed.
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Plays
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Description
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Play trias
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The reservoirs correspond to fluvial channels at the top of the grabens associated with the Triassic rifting, forming fault traps with structural closures located in particular on the Touggourt vault. The Mother Rock corresponds to the Hot Shales of the Silurian.
The cover corresponds to the volcanic rocks for the Lower Series and to the evaporites of the roof of the Triassic and the Lias for the levels T1 or even T2. |
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Jurassic Play
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Occurs as folds or horsts located above Triassic faults reactivated and inverted during Austrian compression in the Lower Cretaceous.
A Callovo-Oxfordian Source Rocks with reduced lateral migration could generate hydrocarbons. The blanket could be intraformational clays of the Malm.. |
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Play Cretaceous
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This play corresponds to reefs developed on shoals associated with NE-SW compressive structures.
Hydrocarbons are essentially trapped in the Turonian - Coniacian reef-facies reservoirs, the traps are of the stratigraphic type. The cover is associated with Senonian clays and evaporites. The source of the hydrocarbons is the clayey limestones rich in organic matter from the Cenomano –Turonian era. |
Saharan Domain
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Plays
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Description
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Cambro-Ordovician
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It is represented by the Cambrian fluvio-deltaic and Ordovician fluvio-glacial units.
supply is provided by radioactive silurian clays El Gassi's clays provide cover for the Cambian, while those of Azzel provide that of the Ordovician. The traps are mainly mixed |
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Siluro-Devonian
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Represented by a clay-sandstone ensemble "SAG", while the Devonian is represented by fluvial to continental sandstones of the Emsian-Siegennian and Gedinnian
supply is provided by radioactive silurian clays Intra-Devonian clays provide the cover. The traps are mixed |
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Carboniferous
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These are the sandstone intervals of shallow marine deposits, as well as the Tournaisian-Visean fluvio-deltaic formations, fed by radioactive silurian and Frasnian clays.
Intra-Carboniferous clays provide the cover Traps are structural type |
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Triassic
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It is the sandstones of the TAGS and the carbonate Triassic which constitute the reservoir element,
supply is provided by radioactive Silurian and Frasnian The clays and evaporites of the Intra-Triassic and Triassic Lias form the cover Traps are structural type associated with faults. |
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Plays
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Description
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Cambro-Ordovician
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It is represented mainly by fluvio-deltaic deposits for the Cambrian and quartzites for the Ordovician.
supply is provided by radioactive silurian clays A powerful silurian clay series, as well as intra-formation clays The traps are mainly mixed |
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Siluro-Devonian
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Represented by a clay-sandstone ensemble; consisting of shallow marine sandstones and fluvial sandstones,
supply is provided by radioactive silurian clays A Frasnian clay series provides the cover. Traps are structural type, mainly represented by faulted anticlines |
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Carboniferous
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These are sandstone lenses which constitute the reservoir levels of this play
supply is provided by radioactive silurian and Frasnian clays Intra-Carboniferous clays provide the cover Traps are structural type |
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Triassic
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It is the low clayey TAGS and carbonate Triassic sandstones that constitute the reservoir element,
supply is provided by radioactive Silurian and Frasnian The clays and evaporites of the Intra-Triassic and Triassic Lias form the cover Traps are structural type associated with faults. |
Amguid-Messaoud oil system
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Plays
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Description
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Cambro-Ordovician
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The tanks of this play, productive in the deposit of Hassi Messaoud; is represented by a thick series of detritic rocks consisting mainly by sandstones, quartzites and conglomerates,
The main rock mother remains the radioactive clays of the silurian. El Gaudsi clays ensure coverage Traps are mixed structural types |
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Ordovician
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Represented by Hamra quartzites, in a solid, well-developed sandstone ensemble
supply is provided by radioactive silurian clays The cover is provided by Azzel clays Traps are mainly structural to mixed |
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Triasic
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The deposits are frankly continental (fluvial) at the base of the series and become increasingly fine and evaporitic towards the top
Silurian and Frasnian radioactive clays provide food Regional coverage is provided by the clay - salt series of the Triassic and Lias for the Triassic reservoir. The traps are of the stratigraphic type. |
Touggourt vault petroleum system
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Plays
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Description
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Ordovician play
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It is located in the base of the filling channels of the glacial valleys.
It is fed per descensum by the bedrock of the Silurian Hot Shales. The blanket is the bedrock itself, namely the Silurian Hot Shales. The bevels formed by the thinning of the Ordovician by the erosion of the Hercynian Discordance constitute our stratigraphic trap. |
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Silurian play
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The Silurian play corresponds to deposits of turbidites or turbiditic channels and deltaic bodies.
The traps are of the stratigraphic and mixed type. They are powered by the Silurian Hot Shales, Coverage is provided by the evaporites of the Triassic. |
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Plays
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Description
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Cambrian
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Represented by a sandstone-conglomerate group of fluvial medium
Power is provided mainly by radiocative Silurian clays It is the Paleozoic clays that provide the cover Traps are essentially structural to mixed type |
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Ordovician
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The supply of this play is provided by radiocative clays of the Silurian, while the cover is by the argillaceous intercalations between the reservoir levels and sometimes the eruptive rocks of the Triassic
Traps are essentially structural type |
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Devonian
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The reservoir levels of this plays are represented by regressive sandstone bars of the shallow marine shelf type interspersed in clay series.
supply is provided by radioactive silurian clays The clayey series of the Lower Devonian as well as the eruptive rocks of the Triassic form the cover Traps are structural to mixed types |
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Carboniferous
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It is represented by a clay-sandstone unit on which a carbonate unit rests.
supply is provided by radioactive silurian clays Carboniferous clays and carbonates and Triassic and Lias clays and evaporites provide the cover The types of traps are essentially stratigraphic, linked to the sandstone and carbonate bodies (lenses and reefs) |
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Trias
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The reservoirs of this play are represented by detrital deposits with fine clayey intercalations of fluvial environment with marine influence.
The radioactive clays of the Silurian represent the main source of supply for this play Coverage is provided by a thick evaporite series of Triassic and Lias Traps are structural to mixed type |
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Jurassic
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This plays contains several levels of sandstone and carbonate reservoirs, having presented good to very good reservoir qualities.
supply is provided by the clay and carbonate levels of the Jurassic, rich in organic matter The clay formations and compact carbonate levels, interspersed between the reservoir levels provide cover Traps are structural, mixed or purely stratigraphic |
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Plays
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Description
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Ordovician
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The fluvio-glacial sandstones of El Goléa and the quartzites of Hamra represent the reservoir element of this play
The supply is provided by radioactive silurian clays A thick silurian clay series provides the cover Traps are structural to mixed type |
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Gedinnian
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Represented by Hamra quartzites, in a solid, well-developed sandstone ensemble
The supply is provided by radioactive clays from the Silurian and the Givetian-Frasnian The cover is provided by the clays of the Middle Devonian Traps are mainly structural to mixed Traps are structural to mixed type |
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Siégénien
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Represented by fluvial deposits
Silurian and Frasnian radioactive clays provide The supply The cover is provided by the clays of the Middle Devonian The traps of this plays are stratigraphic Traps are structural to mixed type |
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Emsien
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It is the coarse and even conglomerate sandstones, deposited in an estuary environment that represent the reservoir element
The supply is provided by radioactive clays from the Silurian and the Givetian-Frasnian The cover is provided by the clays of the Middle Devonian Traps are structural to mixed type |
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Tunisian
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The Tournaisian sandstones are characterized by a fluvio-estuarine to deltaic type facies
The supply is provided by radioactive clays from the Silurian and the Givetian-Frasnian Tournaisian clays form the cover Traps are structural to mixed type |
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Plays
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Description
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Ordovician play
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These are fine and distal sandstone reservoirs
Silurian clays are the main source of The supply Coverage is provided by Ordovician and Silurian clays Several types of traps can exist; structural and stratigraphic |
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Siegenian-Gedinian Play
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The progradation sequences (clay-sandstone alterations) showed good petrophysical characteristics
It is the silurian clays that would fuel this play The cover is provided by the clays of the Lower Devonian and those of the Carboniferous Trapping is often mixed because of the superposition of the sandstone lenses and the associated wrinkling. |
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Famennian Play
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The reservoir is clastic, represented by thick sandstone banks
The power supply for this plays would be provided by Silurian and Givétien-Frasnien clays Famennian clays and those of Visean would provide the cover Several types of trap may exist |
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Play Viséen
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This reservoir is made up of carbonate bioconstructions whose cover is provided by intra-Carboniferous clays; The supply could be provided by muddy clays and limestones of the VIsean
The trap is of the stratigraphic type (they are mud-mounds) |
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Plays
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Description
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Ordovician
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The reservoirs of this plays are represented by fine quartzitic facies, sometimes clayey coastal bars evolving into fluvial deposits
The supply would be provided by radioactive silurian clays A thick silurian clay series provides the cover Traps are structural to mixed type |
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Inferior Devonian
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Represented by tidal marine deposits of fine sandstone with clayey cement evolving towards coastal bars
The supply would be provided by radioactive silurian clays The cover would be provided by the clays of the Middle Devonian Traps are structural to mixed type |
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Strunien-Tournaisien
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These are fine sandstone deposits with silico-clay and carbonate cement that constitute the reservoirs for this plays.
The supply would be provided by radioactive silurian clays The cover would be provided by the clays of the Middle Devonian Traps are structural to mixed type |
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Plays
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Description
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Ordovician
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Forms mainly of clayey quartzitic sandstones, its porosity is of the order of 5% and the permeability is very low.
The source rocks are the radioactive graptolite clays of the basal Silurian The cover is provided by silurian clays. The traps are of mixed types |
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Devonian
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Represented by four sandstone bars, with useful sandstone thicknesses of up to 50 meters
The main source rocks are the radioactive graptolite clays of the Basal Silurian and the Frasnian. Middle Devonian clays provide cover for Lower Devonian reservoirs. The traps are of mixed type |
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Carboniferous
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Represented by fine to very fine sandstones, with porosity of 28% and good permeabilities.
Upper Devonian clays, in particular Frasnian, feed this play. Coverage of Viséen B is ensured by clays of Viséen C The Strunian-Tournaisian reservoirs are covered by upper Tournaisian and Viséen A clays.. |
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Plays
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Description
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Cambro-Ordovician
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The reservoir is made up of a set of units ranging from the Cambrian (Unit II) to the Ordovician (Units III and IV).
Unit IV of the Summit Ordovician is the main reservoir in the region. The reservoir facies is dominated by fine to silty clay sandstones at the base and becomes clean and coarse at the top. The main source rock capable of supplying the Cambro-Ordovician reservoirs consists of radioactive basal clays from the Silurian period. The cover is provided by silurian clays. The traps are of mixed types |
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inferior Devonian
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The Gédinnien reservoir is made up of fine sandstone and silts. Deposition environments are shallow marine with a tendency to containment
The main source rock that feeds the reservoirs of the Gedinnian is the clayey Silurian. The maturation of this level increases from south to north of the Sbâa basin. Middle and Upper Devonian clays provide good cover for Gedinnian sandstones. The traps are of mixed type |
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Carboniferous-Upper Devonian
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This reservoir is formed by fine, bioclastic sandstones, with the presence of glauconia. These sandstones are in the form of marine bars of 20 to 50 meters
The source rock likely to supply the Tournaisian-Strunian reservoirs is the Frasnian, The Strunien-Tournaisien reservoir is covered by the clays of the Viséen and those of the Namurian. Traps are of two types: structural and stratigraphic |