Petroleum Geology Synopsis of Azraq, Safawi and Sirhan Blocks....Geologist Saud Al Nabulsi Senior Manager / Geology Sonoran Energy Jordan

Petroleum Geology Synopsis:

Jordan:

• Jordan I s located in the NW Corner of the stable shelf of the Oil Rich Arabian Peninsula…
• Its total area is 92000 Sq. km. out of which 7500 Sq. km are sedimentary
• Paleozoic Basins (3-8km, clastics) Sirhan basin, Risha Plateau
• Mesozoic Basins 3-5500km Carbonates), Azraq Basin, Basalt Plateau
• Cenozoic Basins (10-15?km Mainly Non Clastics)  Dead Sea basin
• Several tectonic events observed in Jordan: 
• Quaternary/Tertiary (Alpine): Red and Dead seas rifting, movement on conjugate faults. 
• Late Cretaceous/ Tertiary (Alpine): Rifting of Azraq graben
• Early Cretaceous: Base Albian unconformity, 500-2500m overburden removed (U. Paleozoic in the southern Jordan, Triassic and Jurassic in northern Jordan).
• Carboniferous-Permian (Hercynian): Base Triassic unconformity.
• Base Silurian (Taconian): Up to 800m of U. Ordovician removed in the northern Sirhan area.
• Base Cambrian (Vendian phases): Pan African unconformity, Saramuj conglomerates, and horst-graben extensional tectonics, Paleozoic Sags.
• Pre Vendian: Consolidation of Arabian Shield

Sirhan Basin:

• Paleozoic Basin with 4000 – 7000 meter thick sediments
• Sirhan is a structurally controlled NW/SE striking Paleozoic basin characterized by the presence of three fault trends (E-W, NW-SE, NE-SW).
• The thicknesses of Paleozoic sediments in Sirhan Basin, as well as their lateral variations combined with tectonic activity is essential for the evaluation of these sediments as potential hydrocarbon system.
• Faulting occurred at different geological times, with alternating episodes of normal and wrench faulting, generating a large variety of structures, faulted blocks, drag folds, flower structures, horsts and grabens.
• Structural traps associated with both compressional and tensional structural styles are anticipated.
• The primary objective in Sirhan area is the upper Ordovician sandstone of Dubeidib formation, which was deposited in a shallow marine environment. This kind of geological environment may provide a wide variety of stratigraphic traps such: -
• The Channel Deposits of Upper Dubeidib
• The Middle Dubeidib tidal inlet associated with eroded shoreline sequences.
• Stratigraphic and combined traps are anticipated especially at the western part.

Reservior  Aspects :

• core study of Sirhan wells show moderate  petrophysical characteristics for the sandstone and carbonate reservoirs.

 The sandstones of the Dubeidib formation are generally very fine- to fine- or medium-grained, and well-sorted, except in some layers of very limited thickness but present in many wells where they become coarse- and even very coarse-grained.

• The sandstones of the Dubeidib formation have undergone various diagenetic transformations that have had an obvious effect on reservoir quality.
• Fractures enhanced the petrophysical characteristics of the Dubeidib Formation

Azraq Basin:

• Azraq basin is a 1500 Sq.km. NW striking, structurally controlled Cretaceous basin. It is located in Amman / Azraq Block (11250 Sqkm.). It lays 120Km to the east of Amman; between the high central plateau in the west and the Basalt Plateau in the east.
• The Azraq Basin is flattened and covered by Paleogene and Neogene rocks. The elevation within the study area varies from 530m ASL to 650m ASL. This 1500 square km, asymmetrical half graben and structurally controlled Late Cretaceous basin is striking to NW/ SE direction. It is limited to the north and east by Fuluq fault and to the south by Siwaqa fault, to the west the strata rises gradually into the Northern Highlands. The basin is deepest in the east and northeastern parts, adjacent to the down thrown side of Fuluq fault.
• It is the only proven oil province in Jordan yet. It contains the small Hamza Oil Field, which was discovered after a successful completion of Hz-1 Well in 1984.
• The Azraq basin has been the site of the early drilling activities undertaken at the beginning of the eighties. Following the oil discovery at Hamza-1 location seventeen (17) wells has been drilled, these included exploration delineation and production wells. More than 13 wells were drilled in other parts of the basin. Recent seismic interpretation indicated that most of the drilled wells were located of structures.
• Two proven carbonates reservoirs of Cenomanian age, in the basin; they are the Shueib and Hummer formations. Shueib is a dolomitized carbonate shelf deposit. The porosity of Shueib formation ranges from 7 - 10 % with 1.3 and 22.8 md The total thickness of this formation is 45 meters. Hummer formation consists of 45 meters carbonates. Its porosity and permeability values are much lower than Shueib formation.   The argillaceous limestone and shale of Wadi Es Esir provide the seal.
• Log interpretation, and core descriptions indicate that  the Paleozoic, Alb/Apt and the Campanian clastic, are potential reservoirs .
• Hamza Oil field was discovered on top of an E/W tilted narrow horst block, with steep flanks. The field is located in Hamza graben, which is a principal sub-basin of the Azraq Graben.
• Hamza oil field is a narrow elongated E/W tilted horst block. The oil is produced from the Cenomanian Shueib and Hummer formations. The produced oil from Hamza oil field is genetically tied to the organic rich rocks of the lower part of Wadi Es Sir formation (Turonian). The oil generated from this interval is sweet (low sulfur), medium gravity (28 – 29 API). The initial oil generation triggered during the Eocene time. Significant generation and migration of the oil occurred in Miocene time.

West Safawi:

• West safawi block is located in northeastern panhandle of Jordan . It limits the NPC’s concession of Risha Block from the west, and Hamza oil filed from the east.   It a part of the Basalt plateau, and comprises some 8850sq.km. It is a part of the northernmost part of the stable shelf of the north Arabia Platform. This block is flattened with land slope of 1.5m/km. its elevation range 530 m ASL to 650 m ASL. Neogene and Paleogene rocks and Basalt’s cover it.
• The large Basalt Plateau  is basically a Mesozoic fault controlled Plateau. The  basalt’s range in thickness from 100 to 600 meters from south to north direction. As Mesozoic underlies the region and Cenozoic section, which attains a thickness of about 2500 meters, this section is similar to that of the Azraq Block, therefore similar plays are expected in this area. The Basaltic cones show strong linearity and pointed to the tensional nature of faulting in this block.
• Structurally the study area is dissected by many NNW/SSE and ENE/WSW sub vertical step faults. These faults are usually show small vertical displacements. Strike slip movement was observed along some of these faults. This system of faults resulted in forming Highs and Lows, where Risha Gas and Hamza oil Fields are located. The structural complexity of the area is manifested by different structural styles, intense deformation, and faulting.
• The majority of fractures associated or in the vicinity of these faults are one of: shear fractures parallel to the fault, shear fractures conjugate to the fault, or extension fractures bisecting the acute angle between these two shear directions.
• Stratigraphic pinch-out in the eastern part of the study area, where the Paleozoic formations are dipping to the east and the Mesozoic beds are dipping to west, provide excellent chances for hydrocarbon entrapment in a Stratigraphic or combined traps.
• The Stratigraphic studies indicate a predominantly Mesozoic (Triassic & Cretaceous) sediments.
• The Silurian sediments occurrence is limited and restricted to the South West and South East.
• The Late Ordovician sand-silt sequence is covering a large area of the block in the East and the South.
• The Cambro-Ordovician and Cambrian sequences down to crystalline basement are present and distributed over the whole area.
• The presence of thick sedimentary sequence (> 6000 m) of Paleozoic and Mesozoic, and the presence of proven excellent source rock layers along with significant burial depth and enough timing are favorable factors for oil and generation. The effects of strong tectonics, resulting in faulting and folding along with regional and local un-conformities provided conditions for hydrocarbon migration and entrapment.
• Hydrocarbon Potential studies indicate the presence of good source, reservoir and seal rocks in Paleozoic and Mesozoic (Triassic) sequences.
• The source rock layers are mature and oil-prone with some post mature and immature layers.
• Reservoir rocks are predicted in Ordovician sequence (Sandstone) and Triassic (Sandstone and Carbonates.
•  Good seal rocks were found in the Ordovician Silty Shale's, Triassic tight carbonates and evaporate. Silurian shale plays both roles, Source and Seal, in the southern parts of the block.
• The QA-1 well, drilled by Petrofina in 1990 is the only exploration well drilled in this large area of basalt. Shows were encountered during the drilling of the Ghareb argillaceous limestone’s (the equivalent of the oil shales found on the surface and in many others areas between 815-1015 meters.
• The study of well sections of QA-1, WH-1, S-H5, F-1 Wells in West Safawi Block, along with some wells in the adjacent areas indicates the presence of good source rocks  in West Safawi Block:
• Cambrian Source Rock – Burj Formation
• Ordovician Source Rock – Hiswa, Lower and Intra Dubeidib Formation
• Silurian Source Rock – Mudawwara Formation
• The Triassic rocks