BULLETIN OF CANADIAN PETROLEUM GEOLOGY VOL 44, NO.4 (DECEMBER 1996), P 615-631 Geologicsetting and hydrocarbon potential of north Sinai, Egypt A.S. ALSHARHAN M.G. SALAH Faculty ofScience Desertand Marine EnvironmentResearch Center UAEUniversity p.o. Box 17777 P.O.Box 17551 Al-Ain, UnitedArab Emirates Al-Ain, UnitedArab Emirates ABSTRACT The Sinai Peninsula is bounded by the Suez Canal and Gulf of Suez rift to the west, the transfonn Dead Sea-Aqaba rift to the east and the Mediterranean passive margin to the north. The stratigraphic section in North Sinai ranges in age from Precambrian to Recent and varies in thickness between 2000 m of mostly continental facies in the south to almost 8000 m of marine facies in the north. Four main tectonic trends reflect the influence of regional tectonic movements on the study area: 1) ENE-WSW-trending nonnal faults at the Triassic, Jurassic and Early Cretaceous levels; 2) NE-SW- trending anticlines at the Late Cretaceous and Early Tertiary levels; 3) NNW-SSE-trending nonnal faults at the Oligocene and Early Miocene levels; and 4) NNW-SSE-trending transfonn faults during the Late Miocene. Several oil and gas fields have been discovered in North Sinai since 1955. The Oligo-Miocene shales, the Early Cretaceous car- bonates and the Jurassic fine clastics are rich source rocks yielding oil and gas in deep source kitchens. The sandstones of the Miocene, Oligocene, Cretaceous and Jurassic ages,the Jurassic carbonates and the Cretaceous carbonates fonn the reservoirs in north Sinai. The intrafonnational Mesozoic and Cenozoic shales and dense carbonates and the middle 4 Miocene 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. REsuME La peninsuledu Sinal estlimitee par Ie canalde Suezet Ie fosse ouestdu golfe de Suez,Ie fossetransfonnant de la mer Morte-Aqabaa l'est et la margepassive de la Mediterraneeau nord. La sectionstratigraphique dans Ie Sinal dunord s'echelonnede Precambriena Holoceneet varie en epaisseurde 2000 m de facies surtout continentauxdans Ie slid a presde 8000 m de faciesmarins au nord. Quatretendances tectoniques principales refletent l'influence desmou-vements tectoniquesregionaux dans la regionetudiee : 1. les directionsENE-OSO des failles nonnalesaux niveauxdu Triassique,Jurassique et du Cretaceprecoce; 2. les directionsNE-SO anticlinalesaux niveauxdu Cretacetardif et du Tertiaireprecoce; 3. la directionNNO-SSE des failles nonnalesaux niveauxde l'Oligocene et du Mioceneprecoce; et4. la directionNNO-SSE des failles transfonnantespendant Ie Miocenetardif. Plusieurschamps petrolireres et de gaz naturelont ete decouvertsdans Ie Sinal du nord depuis1955. Les schistesdu Oligo-Miocene,les carbonatesdu Cretace precoceet les clastiquesa grainsfins du Jurassiquesont de riches roches-mereproduisant du petrole et du gaz dansIe cuisines-mereprofondes. Les gresd'age Miocene,Oligocene, Cretace et Jurassique,les carbonatesdu Jurassiqueet les carbonatesdu Cretacefonnent les reservoirsdans Ie Sinal du nord. Les schistesintrafonnationels du MesozoIqueet du CenozoIqueet les carbonatesdenses et Ie Miocene moyendeshydrates fonnent les obturations.Les piegesstructuraux, stratigraphiqueset line combinaisondes deux se trouventdans la region etudiee.Le district du Sinal du nord possede de bonnepossibilite pourI' exploitationde petrole.Seuls quelques jeux ont ete testes. Traduit par Marie-LouiseTomas lNTRODUcnON 1962)(Fig. 1). The central and northernsectors of the SinaiPeninsula are covered with a northward-draining limestone The Sinai Peninsula,the commonpart of Africa and Asia, plateauwith a seriesof northeast-trendinganticlinal and syn- is triangular in shapeand occupiesan area of almost 60 000 km2(Fig. 1). It is separatedgeographically from Africa by the clinal jebels (mountains). These folds, extending from the SuezCanal and the Gulf of Suezrift. The southernsector of WesternDesert in the westto Jordanand Syria in the east,fol- the peninsula is occupied by rigid Precambrian basement low the Syrian Arc System.Generally, the elevationof thesejebels rocks that reachelevations of 2640 m in JebelKatherine (Said, decreasesnorthwards to 1090,890 and 735 m in Jebels 615 A.S.ALSHARHAN and M.G. SAlAH Yelleg,Halal and Maghara,respectively (Fig. 1). TheseSyrian STRAllGRAPHY arc folds sink seawards under a Quaternary coastal plain. The lithostratigraphic units of the north Sinai district have Farthernorth, a broad tract of sanddunes runs parallel to the been defined from examination of measured sections and sub- Mediterranean coast and the Bardwail Sabkha (known as surface cores, electric logs tied to microfaunal and palynologi- Bardwail Lake) (Fig. 1) and ranging in elevationfrom 10 to cal studies of ditch samples and thin sections (Shata, 1956; 1000m. Said, 1962, 1990; Al Far, 1966; Neev, 1975, 1977; Beyth, The study area is located in the northernpart of Egyptian 1981; Jenkins et ai., 1982; Aromar and Afifi, 1992; Zaghloul Sinai and is delineatedby longitudes32°35' and 34°25' E and and Khidr, 1992; EGPC, 1994). In this study, the lithostrati- latitudes 29°55' and 31°30' N, embracing an area of almost graphic units in the north Sinai district have been divided into 28000 km2 that averages175 km in length and 150 km in four major sequences which vary in both thickness and facies width. The northernpart of the studyarea is locatedin the off- within the northern and central sectors of the north Sinai area. shoreMediterranean (Fig. 1). A lithostratigraphic column of the study area is given in Figure The main target of this paper is to describethe geology, 3. hydrocarbonpotential and tectonic influence on hydrocarbon generation,migration and accumulationwithin the north Sinai PALEOZOICSEQUENCE area.This studycovers in detail the geologyand hydrocarbon The Paleozoic succession has been penetrated mostly in the habitatof the onshoreand offshoreareas of north Sinai. As the southern wells in the study area, Nakhl-l, Abu Hamth-1 and authors are aware, most of the previous work was mainly El Hamra-1, with an average thickness of 550 m. It is present localized or focusedon certaingeological aspects, e.g., stratig- in the surface exposures at Durba-Araba and Jebel Urn raphy,structure, sedimentology, etc. Bogma, southwest Sinai. Farther north, the Paleozoic section is assumed to lie at great depths as the well Waker-1 (Fig. 2) ,XPLORATION HISTORY was bottomed in the Oligocene rocks at depth of 4733 m. Generally, the thickness of the Paleozoic section increases In additionto being very close to the prolific Gulf of Suez northwards and there is a greater marine influence on the oil basin in which the first discovery, Gemsa oil field, was facies (Fig. 4). This succession is subdivided into the follow- made in 1886,north Sinai containsseveral interesting surface ing groups and formations: Qebliate Group (Cambro- geologic features which made it an attractive exploration Ordovician), represents the oldest Phanerozoic regressive prospect.The explorationfor oil in Sinai beganin 1910when marine facies terminating in a fluviatile facies and includes the Sinai PetroleumSyndicate (SPS) drilled a dry hole Tanka- two formations, the Araba and Naqus (Hassan, 1967); Urn 1 near an oil seepin westSinai (EGPC,1986). Since then,the Bogma Formation (Lower Carboniferous); Ataqa Group Anglo Egyptian Oil Fields, Standard Oil of Egypt and the (Upper Carboniferous), proposed by Soliman and El Fetouh Socony Vacuum Oil Company(the Egyptian subsidiariesof (1970), includes two formations, the Abu Durba and Rod El Shell, Esso and Mobil, respectively)conducted detailed sur- Hamal; and Budra Formation (Permian?) face geologic mapping,carried out severalgravity and mag- TRIASSIC TO EARLY CRETACEOUSSEQUENCE netic surveysand drilled severalwells in the centraland north- ern Sinai without any success.The drilling ceasedduring the This sequence is the thickest section in the stratigraphic col- SecondWorld War (WWII) and attentionwas focusedto the umn of the onshore part of the study area as indicated from the eastern coast of the Gulf of Suez, south of the study area, well Halal N-1 (Fig. 2), which started in the Upper Cretaceous section and bottomed at 4313 m in the Triassic sediments. It where three oil fields, Sudr, Asl and Matarma,were discov- contains potential source, reservoir and seal rocks. It is present ered between1945 to 1948(Fig. 1). During the occupationof on the surface as well as the subsurface and consists of the fol- Sinai by Israel (1967-1979),the Israeli explorationistscon- lowing units: 1) Arif El Naqa Formation (Triassic), continental ducted several additional gravity, magnetic and seismic sur- clastics and marine limestones exposed in Jebel Arif El Naqa in veys over the onshoreand offshore parts of north Sinai and the southeastern part of the study area with vertebrate bone frag- drilled 17 wells, resulting in the discoveryof Sadotgas field in ments and plant remains recorded in the upper and lower parts, 1975 (Fig. 1). Since 1979,the Egyptian General Petroleum respectively, is encountered in the Abu Hamth-1, Nakhl-1, El Corporation (EGPC) launched an exploration program and Hamra-1 and Halal N-l wells (Fig. 2); 2) Maghara Group awardedexploration rights to severalwestern oil companiesto (Jurassic To Early Cretaceous), shallow shelf limestone and flu- explore for hydrocarbonsin north Sinai, e.g.,Conoco, Amoco, vial to continental clastics cover a broad area of north Sinai and