10 | Halliburton Landmark
or bioherm facies ) and / or secondary reservoir enhancement ( karstification ). This is the basis for a screening workflow , which highlights subcrop trap exploration potential . Details of this screening workflow are available to Neftex subscribers of the Middle East region in
this GeoInsight report .
The results of the subcrop screening ( Figure 6 )
reveal some important trends that reconcile with the distribution of fields within a
Cenomanian‐Turonian reservoir interval , many of
which have a subcrop component . These include :
» The Mishrif trend of south-eastern Iraq ( 1 ). High primary reservoir quality occurs
in shoals and patch reefs . This trend is associated with giant and supergiant fields ( e . g . Rumaila Field ) and accounts
for approximately 30 % of Iraq ’ s oil reserves ( Mahdi et al ., 2013 ).
» The Sarvak trend of the Dezful Embayment , Iran ( 2 ). Platform interior facies have been significantly enhanced
through karstification related to sea-level fall and Turonian uplift ( Malekzadeh et al ., 2020 ).
» The Natih trend of northern Oman ( 3 ). Reservoir quality is significantly enhanced through karstification beneath the Turonian unconformity ( van Buchem et al ., 2002 ).
» The Mishrif trend on the Eastern Platform , UAE ( 4 ). This trend is characterized by excellent primary reservoir quality in shelf margin shoals and biostromes , with reservoir quality further enhanced through karstification beneath the Turonian unconformity . This trend includes giant and supergiant fields , such as Fateh ( Videtich et al ., 1988 ) and Umm al Dalkh ( Neo , 1996 ) in the UAE , and the Sirri A , B , C , and D fields ( Farzadi , 2006 ) in Iran .
Figure 6 > Map showing the simplified and generalized extent of potential carbonate reservoirs within Cenomanian – Turonian subcrop beneath the regional Turonian unconformity . This is overlain by hydrocarbon fields with a Cenomanian – Turonian carbonate reservoir interval . Note that the screening output reconciles with prolific reservoir trends ( labeled ), many of which have a subcrop component : 1 ) The Mishrif trend of south-eastern Iraq ; 2 ) The Sarvak trend of the Dezful Embayment , Iran ; 3 ) The Natih trend of northern Oman ; 4 ) The Mishrif trend on the Eastern Platform , UAE ; and 5 ) Exploration opportunities within the Rub Al Khali area of Saudi Arabia .
This area is more frontier , but the results of this
screening process predict high primary reservoir quality with the potential for karstification beneath the Turonian unconformity .
SUMMARY
There are exploration opportunities within Middle Cretaceous carbonate reservoirs in
stratigraphic traps . Successful exploration for this play will require a detailed understanding of paleogeography , platform morphology , depositional facies , and controls on reservoir
quality , all of which can be achieved by applying a sequence stratigraphic model . This model underpins the entire exploration workflow — from GDE mapping to subcrop screening — and forms the framework for successful exploration across the entirety of the Arabian Plate .
ACKNOWLEDGEMENTS
The subcrop screening also highlights significant exploration opportunities away from known fields . For instance , there are high-graded areas within the Rub Al Khali of Saudi Arabia ( 5 ).
The authors are grateful to Thandeka Mlambo and Sophie Evans for assistance in well interpretation and to Rebecca Head for reviewing the article .