Syrian Offshore: Exciting New Frontier

Author Steven Bowman and Toril Leite Jensen, CGGVeritas

With the announcement of the 2011 Syrian International Offshore Bid Round, interested oil and gas exploration companies have an exciting opportunity to assess the hydrocarbon potential of this highly prospective region.

The ancient city of Palmyra in central Syria was an important trading post. Photo: Halfdan Carstens

The Eastern Mediterranean is a tectonically complex region with offshore Syria located above the plate tectonic boundary between the African and Eurasian plates defined by the Latakia Ridge System. Further to the east the Dead Sea transform fault system separates the African and Eurasian plates from the Arabian plate with a triple junction situated onshore in north western Syria.

True Frontier Area

This underexplored region has recently become the focus of increased industry interest due to three major biogenic gas discoveries, Tamar, Dalit, and Leviathan in the offshore southern Levantine Basin. The discoveries were made in high-quality Lower Miocene turbidite reservoirs with total combined recoverable reserves of approximately 25 Tcf gas. Several exploration and appraisal wells have been drilled within the offshore southern Levantine Basin resulting in six gas discoveries.   

Offshore Syria, however, can be considered as an area of true frontier exploration given that no wells have yet been drilled. The closest offshore well is Ayse-1 located just over 10 km to the north of the Syria-Turkey maritime border. It was drilled in 1981 within the Iskenderun Basin and was declared as a dry hole. 

Structural lineaments offshore Syria displayed on the Late Cretaceous unconformity time structure map, illustrating the Latakia Ridge System that defines the Levantine, Cyprus, and Latakia Basins. Compressional faults are displayed in black and extensional faults in blue. Source: CGGVeritas

Four wells were drilled onshore Syria east of the city of Latakia, within 5 km of the coastline, as part of a drilling campaign by the Syrian Petroleum Company during 1981-84.  

The first of these four wells to be drilled was Fidio-1 which was declared as being dry, although small amounts of gas were encountered within Lower Cretaceous carbonates. The Latakia-1 well encountered gas shows within Upper Cretaceous and lower Tertiary carbonates and oil shows were present within fractured Lower Cretaceous clastics. The Latakia-2 well recovered combustible gas from Eocene and Oligocene carbonates and heavy oil and gas shows were encountered within Upper Cretaceous carbonates.   

The Latakia-3 well was drilled above the Latakia Ridge System further north of the other three wells, all of which had been within the northern extension of the Levantine Basin. It was declared as dry, although heavy oil shows and asphalt were encountered within the deepest section of the well and gas shows were recorded at several intervals within the Oligocene and Eocene. The Cretaceous – Tertiary section encountered was repeated up to four times or more, indicating that the area has been intensely faulted and compressed. 

Well correlation panel through the Latakia-1, -2, and Fidio-1 wells. The wells provide a roughly East-West transect from a proximal to a distal setting within the northern extension of the Levantine Basin. Source: CGGVeritas

Three Sedimentary Basins

Three sedimentary basins, Levantine, Cyprus, and Latakia, have been identified from the seismic data, each with a unique structural and stratigraphic history. The basins are defined by large structural lineaments, the Latakia, Larnaca and Tartus Ridges, that define the Latakia Ridge System. They developed as compressional fold-thrust belts during the middle to Late Cretaceous contemporaneous with plate-tectonic convergence between the African and Eurasian plates. Compression continued through to the Late Miocene prior to a reorganization of the plate-tectonic stress regime which led to the establishment of sinistral strike-slip conditions that created significant uplift and deformation.  

The Levantine Basin is interpreted as having developed during the Middle Jurassic. The main phase of sedimentation offshore Syria occurred from the Late Cretaceous onwards within a foreland basin setting that developed ahead of the Latakia Ridge System as a result of lithospheric loading from the emplacement of late Maastrichtian-aged ophiolites. This is a relatively new interpretation of the data based upon the results of the first ever deepwater exploration wells to be drilled within the Eastern Mediterranean in the offshore southern Levantine Basin. The Cenozoic section is believed to be much thicker offshore Syria than previously thought, with a major unconformity that was initially assigned a Late Jurassic age now assigned to the Late Cretaceous age.

Seismic section across the southern Latakia Ridge displaying the Cyprus and Levantine Basins situated on either side. Source: CGGVeritas

The Cyprus Basin developed above the Latakia Ridge System following the emplacement of ophiolites. It is a broad zone of deformation defined by thrusting and folding that was subsequently re-activated during the Early Pliocene under sinistral strike-slip compression leading to the initiation of back-thrusting that formed large positive flower and pop-up structures. This late-stage deformation produced several potential hydrocarbon traps often with stacked reservoirs.   

The youngest of the three basins is the Latakia Basin, where sedimentation is interpreted to have been initiated during the Early to Middle Miocene, above an ophiolitic basement analogous to the Iskenderun Basin further to the north, offshore Turkey. The north-western part of the basin is characterized by thick diapiric Messinian salt whilst the eastern part of the basin is characterized by deep trans-tensional pull-apart basins that initiated during the Pliocene.  

Working Petroleum System

There is significant evidence for a working petroleum system offshore Syria.   

Numerous oil and gas shows have been observed in wells along the Levant Margin, and seismic observations reveal the presence of multiple Direct Hydrocarbon Indicators in the form of gas chimneys, flat-spots, and bright-spots, some of which may represent billion-barrel/ or multi-Tcf exploration targets. Ocean Basin Screening carried out by FugroNPA using satellite imagery reveals the presence of several good, repeating oil slicks, interpreted as naturally occurring oil seeps that correspond to geological features observed on seismic.   

Prospective reservoirs range in age from Triassic to Pliocene-Quaternary and include Lower Miocene deepwater turbidite sands analogous to those encountered in the Tamar, Dalit, and Leviathan discoveries. The complex evolution of each of the three sedimentary basins has produced an array of potential structural and stratigraphic trapping mechanisms including thrust fault anticlines, tilted fault blocks, salt-influenced traps, carbonate reefs, and basin margin onlaps/pinchouts. 

Bid Round Terms CGGVeritas database of multi-client long-offset 2D seismic data offshore Syria acquired in 2005 along with the three blocks to be offered in the second Bid Round. Source: CGGVeritas The Bid Round, which was announced on March 24, 2011 by the Syrian Ministry of Petroleum and Mineral Resources and the General Petroleum Corporation (GPC), invites international oil and gas exploration companies to explore, develop and produce hydrocarbons from three offshore blocks in the Mediterranean Sea, according to a production sharing contract. The size of the area is 9,038 km2, and the blocks are approximately 3,000 km2 each. Bidders may submit their offers for one or more offshore blocks and a separate offer for each block is required.    CGGVeritas acquired 5,000 km of long-offset multiclient 2D seismic data offshore Syria in 2005 in water depths ranging from 500 to 1,700 m. To participate in the Bid Round, it is conditional to license at least 3,000 km of seismic data exclusively from CGGVeritas according to the provisions described in the technical part of the Tender Book. In addition to the original survey data, CGGVeritas is offering an interpretation package and report, gravity data, seep data (in collaboration with FugroNPA) and a reprocessed seismic dataset, currently in production.    As part of an exclusive contract with the Ministry and GPC, CGGVeritas is also providing the technical support for the Bid Round. CGGVeritas will co-host roadshow events and data reviews with the Round organizers in Damascus and London for companies interested in the official available technical data. The closing date for the Bid Round is 5th October 2011 at 14.00 hrs Damascus local time.

Looking Ahead 

Following successful reprocessing test results, CGGVeritas is currently reprocessing the entire 2005 data set. The latest processing techniques have been applied with the aim of attenuating multiples, increasing the signal-to-noise ratio, enhancing reflector continuity, and improving imaging of steeply dipping reflectors. The results are extremely encouraging and provide a much clearer and more easily interpretable image. Similar results are expected to be achieved across the whole survey with significant uplift in the imaging of DHIs and sub-Messinian salt structures and stratigraphy.   

There is no doubt that recent findings have enhanced Syria’s hydrocarbon prospectivity. Should Syria deliver on its hydrocarbon potential, the country has the infrastructure in place to meet export requirements. There are two oil export terminals, one in the port of Tartous and the second in Banias. The first serves a domestic pipeline bringing 250,000 bopd from Syrian Peroleum Company’s north-eastern fields. The port of Tartous also has a large Free Zone Area with storage facilities for service companies to set up base. The second oil terminal, in Banias, serves a 100,000 bopd pipeline from Al-Thayyem and other fields. 

Author’s note A full version of this Syria article including a comprehensive description of the regional geology will be published in GeoArabia Vol. 16. No. 3: Bowman, S.A. 2011. Regional seismic interpretation of the hydrocarbon prospectivity of offshore Syria.  More information about the Round can also be found on the following websites: www.gpc-sy.com and www.cggveritas.com/syria.