Geologic Setting And Hydrocarbon Potential Of North Sinai .

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BULLETIN OF CANADIAN PETROLEUM GEOLOGYVOL 44, NO.4 (DECEMBER 1996), P 615-631Geologicsetting and hydrocarbon potential of north Sinai, EgyptM.G. SALAHA.S. ALSHARHANFaculty ofScienceUAEUniversityP.O.Box 17551Al-Ain, UnitedArab EmiratesDesertand Marine EnvironmentResearchCenterp.o. Box 17777Al-Ain, UnitedArab EmiratesABSTRACT4The Sinai Peninsula is bounded by the Suez Canal and Gulf of Suez rift to the west, the transfonn Dead Sea-Aqabarift to the east and the Mediterranean passive margin to the north. The stratigraphic section in North Sinai ranges in agefrom Precambrian to Recent and varies in thickness between 2000 m of mostly continental facies in the south to almost8000 m of marine facies in the north. Four main tectonic trends reflect the influence of regional tectonic movements onthe study area: 1) ENE-WSW-trending nonnal faults at the Triassic, Jurassic and Early Cretaceous levels; 2) NE-SWtrending anticlines at the Late Cretaceous and Early Tertiary levels; 3) NNW-SSE-trending nonnal faults at theOligocene and Early Miocene levels; and 4) NNW-SSE-trending transfonn faults during the Late Miocene. Several oiland gas fields have been discovered in North Sinai since 1955. The Oligo-Miocene shales, the Early Cretaceous carbonates and the Jurassic fine clastics are rich source rocks yielding oil and gas in deep source kitchens. The sandstonesof the Miocene, Oligocene, Cretaceous and Jurassic ages,the Jurassic carbonates and the Cretaceous carbonates fonnthe reservoirs in north Sinai. The intrafonnational Mesozoic and Cenozoic shales and dense carbonates and the middleMiocene anhydrite fonn the seals. Structural, stratigraphic and combination traps are encountered in the study area.The north Sinai district has a good oil exploration potential. Only a few plays have been tested.REsuMELa peninsuledu Sinal estlimitee par Ie canalde Suezet Ie fosseouestdu golfe de Suez,Ie fossetransfonnantde lamer Morte-Aqabaa l'est et la margepassivede la Mediterraneeau nord. La sectionstratigraphiquedansIe Sinal dunords'echelonnede Precambriena Holoceneet varie en epaisseurde 2000 m de facies surtoutcontinentauxdansIeslid a presde 8000m de faciesmarins aunord. fluence desmou-vementstectoniquesregionauxdansla regionetudiee: 1. les directionsENE-OSOdesfailles nonnalesaux niveauxduTriassique,Jurassiqueet du Cretaceprecoce;2. les directionsNE-SO anticlinalesaux niveauxdu Cretacetardif et duTertiaireprecoce;3. la directionNNO-SSEdesfailles nonnalesaux niveauxde l'Oligocene et du Mioceneprecoce;et4.la directionNNO-SSEdesfailles transfonnantespendantIe Miocenetardif. Plusieurschampspetrolirereset de gaznaturelont etedecouvertsdansIe Sinal du nord depuis1955.Les schistesdu Oligo-Miocene,les carbonatesdu Cretaceprecoceet les clastiquesa grainsfins du Jurassiquesontde richesroches-mereproduisantdu petrole et du gaz dansIecuisines-mereprofondes.Les gresd'age Miocene,Oligocene,Cretaceet Jurassique,les carbonatesdu Jurassiqueet lescarbonatesdu Cretacefonnentles reservoirsdansIe Sinal du nord.Les schistesintrafonnationelsdu MesozoIqueet duCenozoIqueet les carbonatesdenseset Ie Miocene moyendeshydratesfonnentles obturations.Les piegesstructuraux,stratigraphiqueset line combinaisondes deux se trouventdansla regionetudiee.Le district du Sinal du nord possedede bonnepossibilite pourI' exploitationde petrole.Seulsquelquesjeux ont etetestes.Traduit par Marie-LouiseTomas1962)(Fig. 1). The centraland northernsectorsof the SinaiPeninsulaare covered with a northward-draining limestoneThe Sinai Peninsula,the commonpart of Africa and Asia,plateauwith a seriesof northeast-trendinganticlinal and synis triangular in shapeand occupiesan area of almost 60 000km2(Fig. 1). It is separatedgeographicallyfrom Africa by the clinal jebels (mountains). These folds, extending from theSuezCanal and the Gulf of Suezrift. The southernsectorof WesternDesertin the westto Jordanand Syria in the east,folthe peninsula is occupied by rigid Precambrian basement low the Syrian Arc System.Generally,the elevationof thesejebelsdecreasesnorthwardsto 1090,890 and 735 m in Jebelsrocks that reachelevationsof 2640m in JebelKatherine(Said,lNTRODUcnON615

A.S.ALSHARHANandM.G. SAlAHYelleg,Halal and Maghara,respectively(Fig. 1). TheseSyrianarc folds sink seawardsunder a Quaternary coastal plain.Farthernorth, a broad tract of sanddunesruns parallelto theMediterranean coast and the Bardwail Sabkha (known asBardwail Lake) (Fig. 1) and ranging in elevationfrom 10 to1000m.The study areais located in the northernpart of EgyptianSinai and is delineatedby longitudes32 35' and 34 25'E andlatitudes 29 55' and 31 30' N, embracing an area of almost28000 km2 that averages175 km in length and 150 km inwidth. The northernpart of the studyareais locatedin the offshoreMediterranean(Fig. 1).The main target of this paperis to describethe geology,hydrocarbonpotential and tectonic influence on hydrocarbongeneration,migrationand accumulationwithin the north Sinaiarea.This studycoversin detail the geologyand hydrocarbonhabitatof the onshoreand offshoreareasof northSinai.As theauthors are aware, most of the previous work was mainlylocalized or focusedon re,sedimentology,etc.,XPLORATION HISTORYSTRAllGRAPHYThe lithostratigraphiccal studies of ditch samples and thin sections (Shata, 1956;Said, 1962, 1990; Al Far, 1966; Neev, 1975, 1977; Beyth,1981; Jenkins et ai., 1982; Aromar and Afifi, 1992; Zaghlouland Khidr, 1992; EGPC, 1994). In this study, the lithostratigraphic units in the north Sinai district have been divided intofour major sequences which vary in both thickness and facieswithin the northern and central sectors of the north Sinai area.A lithostratigraphic column of the study area is given in Figure3.PALEOZOICSEQUENCEThe Paleozoic succession has been penetrated mostly in thesouthern wells in the study area, Nakhl-l, Abu Hamth-1 andEl Hamra-1, with an average thickness of 550 m. It is presentin the surfaceexposuresat Durba-Arabaand Jebel UrnBogma, southwest Sinai. Farther north, the Paleozoic sectionis assumed to lie at great depths as the well Waker-1 (Fig. 2)was bottomedGenerally,In additionto being very closeto the prolific Gulf of Suezoil basin in which the first discovery, Gemsa oil field, wasmade in 1886,north Sinai containsseveralinterestingsurfacegeologic features which made it an attractive explorationprospect.The explorationfor oil in Sinai beganin 1910whenthe Sinai PetroleumSyndicate(SPS)drilled a dry hole Tanka1 nearan oil seepin westSinai (EGPC,1986).Sincethen,theAnglo Egyptian Oil Fields, Standard Oil of Egypt and theSocony Vacuum Oil Company(the Egyptian subsidiariesofShell, Esso and Mobil, respectively)conducteddetailed surface geologic mapping,carried out severalgravity and magnetic surveysanddrilled severalwells in the centraland northern Sinai without any success.The drilling ceasedduring theSecondWorld War (WWII) and attentionwas focusedto theeasterncoast of the Gulf of Suez, south of the study area,where three oil fields, Sudr, Asl and Matarma,were discovered between1945to 1948(Fig. 1). During the occupationofSinai by Israel (1967-1979),the Israeli explorationistsconducted several additional gravity, magneticand seismic surveys over the onshoreand offshore parts of north Sinai anddrilled 17 wells,resulting in the discoveryof Sadotgasfield in1975 (Fig. 1). Since 1979,the Egyptian General PetroleumCorporation (EGPC) launched an exploration program andawardedexplorationrights to severalwesternoil companiestoexplore for hydrocarbonsin north Sinai, e.g.,Conoco,Amoco,Total, BP,Elf Aquitaine and IEOC (the InternationalEgyptianOil Company).Theseresulted in the discoveryof the Tineh,Port Fouad,Abu Zakin, Wakar, SouthRafah and Mango oiland gas discoveries(Fig. 1). In additionto thesediscoveries,severalwells have encounteredgood oil and/or gas shows(EGPC,1986)(Fig. 2).units of the north Sinai district havebeen defined from examination of measured sections and subsurface cores, electric logs tied to microfaunal and palynologi-in the Oligocenethe thicknessrocksat depth of 4733 m.of the Paleozoicsection increasesnorthwards and there is a greater marine influence on thefacies (Fig. 4). This succession is subdivided into the following groupsand ents the oldest Phanerozoic regressivemarine facies terminating in a fluviatile facies and includestwo formations, the Araba and Naqus (Hassan, 1967); pper Carboniferous), proposed by Soliman and El Fetouh(1970), includes two formations, the Abu Durba and Rod ElHamal; and Budra Formation (Permian?)TRIASSICTO EARLY CRETACEOUSSEQUENCEThis sequence is the thickest section in the stratigraphic column of the onshore part of the study area as indicated from thewell Halal N-1 (Fig. 2), which started in the Upper Cretaceoussection and bottomed at 4313 m in the Triassic sediments. Itcontains potential source, reservoir and seal rocks. It is presenton the surface as well as the subsurface and consists of the following units: 1) Arif El Naqa Formation (Triassic), continentalclastics and marine limestones exposed in Jebel Arif El Naqa inthe southeastern part of the study area with vertebrate bone fragments and plant remains recorded in the upper and lower parts,respectively, is encountered in the Abu Hamth-1, Nakhl-1, ElHamra-1 and Halal N-l wells (Fig. 2); 2) Maghara Group(Jurassic To Early Cretaceous), shallow shelf limestone and fluvial to continental clastics cover a broad area of north Sinai andextend from the Western Desert of Egypt, through north Sinai,to Negev Desert, Jordan and Syria. In north Sinai, Jurassic rocksare exposed in the cores of several structures (Jebels Maghara,Rizan Aneiza, Minsherah and Arif El Naqa) (Fig. 1) and areencountered in 17 wells in the onshore and offshore parts of thestudy area. The thickestand most completesectionof the

.)-. .HYDROCARBONPOTENTIALOF NORTH SINAI,EGYPT617 I}j)@@@, I!.n00UWJt!\ IN!051JI:!l@iIj) IIIEASTERNDESERT '(JREDSEA \PRECAMBRIANJEBELTOWN@OIL AND/OR GAS DISCOVERY0WELL LOCATIONFig. 1. Generalizedgeological map and oil fields in northern Sinai.BASEMENT4080 Km

.33 ' 30'32 130'MEDITERRANEAN\SEA34 1 30"N\ -- -Bravo-1-L*Heltzi -1 Sharsheret-,Neirim 1Halutsa.t1#2 Hazeram-1-.Arif-1ISRAELSinaf.1.Kabrit-1'Central SinaiGiddi-1 SUEZAttaqt, .Dry WellOilWell"* Gas Well EI Hamra-1Abu Hamth-t - -Nakhl-1- - Darag-1CityCD Sub-Basin0/.20kmSTUDY'IAREA' ,'(j'REI)\\Fig. 2. Well locations and major subbasins in the study area.Jurassic rocks in north Sinai is that of Jebel Maghara, where itreaches to almost 2000 m (AI Far, 1966), and is used in thisstudy as a reference section. The Maghara Group is subdividedinto the following formations, in ascending order: MashabaFormation (Lower Lias); Rajabiah Formation (Lower Lias);Shusha Formation (Upper Lias); Bir Maghara Formation(Bajocian to Early Bathonian); Safa Formation (EarlyBathonian); Masajid Formation; Rakeib Formation (Neocornianto Barrarnian); and Rizan Aneiza Formation (Aptian to Albian). Oeren-1-1A.S. ALSHARHANand M.G. SAlAH618UPPERCRETACEOUSTO LATE EOCENESEQUENCEThis sequenceis characterizedby the predominanceof carbonatesin the lithostratigraphicunits of the onshorepart of thestudyareaseveralof which are potentialreservoirs.It is present on the surfaceand the subsurfaceof north Sinai (Fig. 4)and consists of two groups, in ascendingorder: Nezzazat(Cenomanianto Santonian)with thicknessesof 732, 845 and945 m in the JebelsMaghara,Arif Al Naqa and Minsherah,

IIIvIII1 ONPOTENTIALOF NORTH SINAI,EGYPTf 0),.0CUII CCKUNITCo)I0IIc.or. 1I J:ICoc.GROUPU.J--.POTENTIALDepositional SettinaLITHOLOGY!;ga:FM. MBR.MBR. UJ- .;.\ "PLEISTOCENEII LATE .ROSETTA/OAWASIMROSETTA I OAWASIMSIDISALEMSIDI SALEM I,(/)ABUMADIMIDDLEOUJKAFR EL SHEIKHKAFR-e Ic(a:G\}'PLIOCENE-'e.EARLY.TAYIBA RED BEDS I OLIGOCENE TAYIBAMAADI/TANKAWit.)lI LATEMOKATTAMMOKATTAM MIDDLEKHABOBA0DARATwEARLYoctIPAlLEOCENwNN « I EBESDUWIITHELMETMATULLAMATULLAfWATAA :::A A :::A WATA A.OADAA.OADARAHA/HALALEARLYRIZANANEIZARAKEIBLATE MASAJIDwoct u MIDIa:I I---I I SHUSHA EARLY .SAFASA FA.GoctBIRMAGHARAMAGHARAcn.-'oJ,'::::::,.GJ ASHABATRIASSICARIF EL NAOAPERMIANBUDRAIn ()--l0N0W oJw Z0IX} ,:ABU DURBA .JiCI:UMBOGMA' --,- t)wIoS'-"-NAOUS I[]I] Sandstone.g- RODELRODEL HAMALHAMALww' 0wmARAB A Coarse sandstoneEJ Siltstone-- -[ZJ .Erosion Volcanics--Fig. 3. Generalized stratigraphic column, depositional environments and hydrocarbon potential of the northern Sinai area (modified after several authors).

IA.S. ALSHARHAN and M.G. SALAH620 Paleozoic JurassicPrecambrianDTriassic:::::::: ,.Paleocene',".'.'.'.'.'.'::.':::::::'::::to Eocene40 km0Post - Cretaceous EoceneBasementLine of SectionFig. 4. Schematic cross-section across the north Sinai area. (modifiec after Shata, 1956).respectively(Fig. 1), and El Egma (Campanian to MiddleEocene) with various thicknesses, facies and conformity withthe overlyingand underlyinglithostratigraphicunits reflectingthe influence of tectonism.OLIGOCENETO LATE MIOCENE SEQUENCEThe Oligocenesediments, known as Tayiba Red Beds(Barakat et ai., 1988), are absent in the southern part of theonshore area due to the emergence of this sector as a result of theinfluence of the early stages of the Gulf of Suez rifting. Theyaverage to 90 m in the eastern part of the study area but increaseabruptly to the west to an average of 750 m and reach up to 1075m west of the Suez Canal (Zaghloul and Khidr, 1992).The Miocene section is well developed in most of the studyarea and is 1100, 1260 and 1350 m thick in the Gal-I, Bardawil1 and Sneh-l wells, respectively.A much thinner Miocenesequence was drilledin wells located over old structural highs(most probably of Syrian Arc trend) that remained highs duringthe Miocene, as in the wells Slave-I, Gofer-l and AI-Arish-l,where it reaches 270, 180 and 200 m, respectively. The Miocenesection is subdivided into two formations, in ascending order:Sidi Salem Formation(Lower to MiddleMiocene)andQawasim/Rosetta Formation (Middle to Upper Miocene).PosT-MIOCENE SEQUENCEThe post-Miocene sediments show marked variations fromone area to another but generally increase in thickness to thewest in the Nile Delta area, following the same trend seen inthe Oligoceneand Miocene sequences.The thicknessesof thepost-Miocene sequenceare 400, 250, 1250 and 1700 m inwells Gal-I, Sneh-l, Qantara-l and El Temsah-l,respectively.The post-Miocenesectionis thin in wells locatedon old structural highs, e.g.,Malha-l, where it has a thicknessof only 88m. The post-Miocenesectionis subdividedinto the followingformations, in ascending order: Abu Madi Formation(Pliocene)and Kafr El Sheikh(Pleistocene)(Said, 1962).STRUCTUREANDTECTONISMThe presentanalysesof the structuralgeologyin the northSinaiarebasedon the interpretationof bothgeophysical(magnetic, gravity and processedseismic) and geological data,including subsurfaceinformation from wells drilled in, andcloseto, the studyarea,surfaceoutcropsand aerialphotographexaminationof the structuralconfigurationof the region.The studyareawasthe subjectof intensivesurfaceand subsurface geological and geophysical investigations duringhydrocarbonprospectingand exploration.Among thesestudies are those by Said (1962, 1990), Al Far (1966), Smith(1971),El Shazlyet ai. (1974), Bartov et ai. (1980),Eyal etai. (1981), May (1991),Moustafa and Khalil (1987), Aal etai. (1992)and Aal and Lelek (1994).The resultsare incorporatedin the currentstudy.The Sinai Peninsulahas attracted the attention of manygeologistsas it is boundedby major tectonic elements.These

A'HYDROCARBONPOTENTIALOF NORTH SINAI,EGYPTeral shearcouple betweennorth Africa and Eurasia (Smith,1971).This shearcouple startedin the Turonian,climaxed inthe Late Cretaceousand decreasedinto the Early Tertiary,causingthe right-lateral rejuvenationof the deep-seatedfaultsin north Egypt (Smith, 1971) (Fig. 5). This tectonic event,known in the Middle East as Syrian arc system,producedaseries of asymmetrical NE-trending, doubly-plunging anticlines in the study area, e.g.,JebelsMaghara,Yelleq, Halal,MinsherahandFallig (Fig. 6).PHASEill: The rifting of the Gulf of Suez,startedbetween24 and 21 Ma, during the latest Oligocene to the earliestMiocene (Evans, 1990),was causedby hthe lithosphere,in addition to an upwelling of hot asthenosphere(Harnmouda,1992).Between20 and 17 Ma, the flanks of this future basinbegantobe uplifted in responseto heating. Both the crustal extensionandtectonicsubsidenceof the axial troughreachedtheir peaksbetween19 and 15 Ma. This tectonicphaseis very clear in thesouthern and southwesternparts of Sinai and dominatedLelek, 1994).PHASE II: During the Late Cretaceousto Early Tertiary NNW-trendingnormalfaults (Fig. 6).PHASEIV: This phaseis representedby theLateMioceneto(Laramide) time, Africa moved west-northwestrelative toEurasia,which closedthe TethysSeaandproduceda right-lat- RecentGulf of Aqabarifting, which was formed by left-lateralare the Mesozoic-Early Cenozoic tectonically-activeTethysSeato the north, the Oligo-MioceneGulf of Suezrifted basinto the west, and the late Miocene to RecenttransformDeadSea-Gulf of Aqaba rift to the east. Each of these major elementshasaffecteddramaticallythe structureandtectonicevolution of the north Sinai area,which has beensubdividedintofour tectonicphases,asfollows:PHASE I: The breakup of north Africa-Arabia in LateTriassic-Liassictime and the openingof the Tethystook placeand reactivatedENE-WSW-orienteddeep-seatedfaults. Thesouthernand central sectorsof Sinai were uplifted, relative tothe northern(onshoreand offshore)(Bartov et aI., 1980).Theinfluenceresultedin the developmentof a thick wedgeof theEarly and Middle Mesozoicsediments(Triassic,JurassicandEarly Cretaceous)in the northern sectorand its abruptthinning to the south(Fig. 5). Structurally,this phasewas dominated by JurassicNW-SE left-lateral oblique extensionwhichresulted in ENE- to NE-trending normal faulting (Aal andACentral SinaiTransitional AreaNorth SinaiUnstable Shelf AreaSouth SinaiStable Shelf.JAFTER taceous ,"""'",, , ,""'""""'", ,, ,',',',',',',',',',',',',',',',',',',',',',',', """'" """"""'"""""""" """'" '"""'"""""'""""""""""""""'" ,',',',',',',',',',',',',',',',',',',',',',',',', ' "'" """"'"":E LBasement0.rTRIASSICPASSIVE CONTINENTALMARGIN50 KM,"""""""'",,',',',',',',',,,,','.'"'"",,',',' ,,' ,',',',',',',',',',',J' .-""""""",,""""""",".',",',','c',','.'.','Fig. 5. Evolutionaryregional relationships.,"""""".,""""",',',' ',',' """"""""""""""V"""""""",'",,.','.'., . c , ,',',',','""'-" .,.',',','.',',',',','1',''. '. ',",','.',',',',,stages of the study area (modified after Bartov et al.,

Geologic setting and hydrocarbon potential of north Sinai, Egypt A.S. ALSHARHAN Faculty of Science . geologic features which made it an attractive exploration prospect. The exploration for oil in Sinai began in 1910 when . Fig. 1. Generalized geological map and oil fields in northern Sinai.

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