Introduction

Carbonate reservoirs have attracted exploration activity for many decades as the global production participation rate of carbonate reservoirs is 60%, and it rises to 70% in the Middle East (Fig. 1). Egypt’s carbonate production, on the other hand, does not exceed 30%. However, General Petroleum Company operates several development leases (Fig. 2B) and has succeeded in raising oil and gas production from complex heterogeneous carbonate reservoirs in mature hydrocarbon rift basins to approximately 60% of the global figure. Additional accomplishments in this investigated brownfield will be based on the delineation of small-scale fault blocks from wells, 3D seismic, calibrated with core and borehole image data (Baaske et al. 2007; Baechle et al. 2007; Barnett et al. 2021; Belde et al. 2017; Betzler et al. 2016; Betzler and Eberli 2019; Bueno et al. 2014; Eberli et al. 2004; Embry et al. 2021; Esestime et al. 2016; Gold et al. 2021; Harvey and Macdonald 2013; Imam et al. 2022; Mahjour et al. 2019; Turner et al. 2023).

Fig. 1
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Global distribution of carbonates. Areas of modern sediments in shallow water are shown in yellow and orange, while modern deep-water sediments are in black patched lines. Prolific oil basins are shown in red-hatched lines. (Akbar et al. 1995; adapted from Blatt et al. 1972; Perrodon 1983)

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Fig. 2
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A Main fault architecture in the Gulf of Suez (Salim et al. 2016) and B Oil discoveries in the Gulf of Suez (Sayed et al. 2023). location of the study area is outlined by the red box

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Many authors explained the role of fault-related changes in carbonate platform accommodation space (Cisne 1986; Leeder and Gawthorpe 1987), such as the Silurian of North Greenland (Hurst and Surlyk 1984), the Cambrian of Sardinia (Cocozza and Gandin 1990), the Lower Carboniferous of northern England (Ebdon et al. 1990), Ireland (Pickard et al. 1994), the Lower Jurassic of the Tethyan region (Santantonio 1994), the Albian of north-west Spain (Rosales et al. 1994), the Lower Cretaceous of Sulawesi, Indonesia (Wilson and Bosence 1997), the Gulf of Aden (Brannan et al. 1997) and the Miocene of the Gulf of Suez (Burchette 1988; James et al. 1988; Bosence 1998; Cross 1996; Cross et al. 1998). Furthermore, syn-rift carbonate reservoirs are developed away from high rates of clastic supply and controlled by the accommodation space generated from extensional rotational fault block movement, paleo-environmental conditions, and eustatic sea-level changes (Bosence et al. 1998; Camoin et al. 2006; Fournier et al. 2005; Montaggioni 2005; Webster and Davies 2003). As technology advances, particularly three-dimensional volumes, the ambiguity of reef accumulation patterns emerge, whether in the shape of interconnected polygonal networks, solitary mounds, or vertical merged and bifurcating ridges (Baechle et al. 2007; Elvebakk et al. 2002; Imam et al. 2022; Samuelsberg et al. 2003; Shehata et al. 2023; Turner et al. 2023).

In the Gulf of Suez (GOS) southern province outcrop Miocene carbonate platforms and reefs are directly developed on the top of the tilted basement fault block of the Esh el Mellaha range (Bosworth and McClay 2001). For example, Jebel Abu Shaar El Quibli (Gregory 1906; Hume 1916; Madgwick et al. 1920), and Ashrafi reef complexes (Roberts and Murray 1984). In the subsurface, the Miocene reef reservoirs have been documented by many authors (Burchette 1988; Cross 1996; El Fakharany et al. 2016; Safa et al. 2021; Salim et al. 2022; Sharaf et al. 2000).

The offshore Bakr-Al-Hamd oil fields are located on the western side of the GOS continental rift basin (Fig. 2). The north-west-trending GOS was active between the Oligocene (Robson 1971), Oligocene–Miocene (Garfunkel and Bartov 1977), or early Miocene (Patton et al. 1994). Based on recent radiometric data from the base-syn-rift basalts, the rifting onset of rifting is dated at 24–23 Ma (Bosworth and Stockli 2016). Dolson et al. (2000, 2014) mentioned that the exploration history in the mature rift basin GOS reached the production plateau in 1980, the field size distributions, however, still show room for several new fields that will be less than 100 MMBOE in size. They also acknowledge that additional assessment by play, trap, or reservoir age provides more refinement, especially if coupled with source, maturation, and migration studies which can quantify volumes of hydrocarbons expelled in each trend.

Bakr-Al Hamd fields are sub-basins in the mature exploration phase and located in the central province of the Gulf of Suez. Bakr field was discovered in 1959. Bakr Brownfield reached a production plateau in the period 1964–1971 with a peak of 18,000 STBO/day in 1965. The production came from Basement, pre-rift, and syn-rift reservoirs (Fig. 4). In 2004, Al Hamd field was discovered 2 km eastward of Bakr field and the production gain was 14,000 STBO/day from Miocene carbonate buildup (i.e., Nullipore), and the localized Eocene Thebes carbonate reservoir. In 2020, the production decreased to 4000 and 8000 STBO/day with cumulative production of 126 MMbbl and 51 MMbbl in Bakr and Al Hamd fields, respectively (Salim et al. 2016).

The objective of this research is to demonstrate the evolution of the syn-rift Early to Middle Miocene carbonate reef buildups in Bakr-Al Hamd ridge. This reservoir is significant because of its long-lived production and contributes to more than half of total oil cumulative production. Additionally, documents an integrated workflow aimed at revitalizing brownfield exploration activity and increasing production performance in a petroliferous rift basin.

Geological settings

Tectonics

The Gulf of Suez represents a continuation of the Red Sea Rift until break-up occurred in the middle Miocene, with most of the displacement on the newly developed Red Sea spreading center being accommodated by the Dead Sea Transform (Colletta et al. 1988; Evans 1988; Steckler et al. 1988; Purser and Philobbos 1993; Patton et al. 1994; Bosworth and Strecker 1997; McClay and Khalil 1998; Orszag-Sperber et al. 1998; Dolson et al. 2014; Bosworth 2015). It was recognized as three large-scale sub-basins with different regional dip polarities (Fig. 2A) separated by two accommodation zones (Moustafa 1976). During its brief post-rift history, the deepest part of the remnant rift topography has been filled by the sea, creating the Gulf of Suez. North of the GOS, the rift becomes indistinct and its exact geometry uncertain, linking eventually to the Manzala rift beneath the Nile delta (Bosworth et al. 2005). The stratigraphic sequences of the GOS are subdivided into three mega-sequences (Darwish and El Araby 1993). Pre-rift mega-sequence comprises Paleozoic to Eocene overlain by the Proterozoic basement rocks. These sediments include both reservoirs and source rocks. Syn-rift mega-sequences represented by Early Miocene to Middle Miocene sediments and post-rift mega-sequences. The pre-rift sequences are nearly consistent in facies while the syn-rift sequences vary rapidly even at the small-scale faulted blocks at the same sub-basin. However, the post-rift sediments are dominated by salt and anhydrite decreasing in thickness from south to north. This variation in syn-rift sediments thickness directly reflects on the 3D seismic image which enhances toward the north sub-basins. The GOS serves as an excellent extensional model to study the interaction between sedimentation and extensional fault development (Gawthorpe et al. 1997).

The offshore Bakr Al-Hamd (B-H) ridges are located in the Central Dip Province of the GOS (Fig. 2) (Moustafa 1976) which is characterized by a regional fault tilting towards the northeast. B-H ridges extend parallel in a NW direction and are included as a part of a major structural ridge known as Gharib-Amer (G-A) ridge (Fig. 3). The ridge hosts several brown oil fields, Fanar-Gharib-Bakr-Al Hamd and Amer (Fig. 3B, C). It is bounded by NW rift parallel fault series which are dissected by NE oblique faults (Fig. 3A). The footwall fault blocks witnessed lowering towards the eastern part representing complex extensional collapsing structural patterns. The mature source rock is located in the western trough and also, in the eastern low stand area (Campanian Brown Limestone; Bosworth and McClay 2001; EGPC 1984; Ghorab 1961; Shaheen and Shehab 1984; Youssef 1957) where oil was charged.

Fig. 3
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Time slice showing high and low anomalies (A) a general setting of Gharib-Amer structural ridge (B), and a base map showing Bakr-Al Hamd oil fields (brown polygon) and the locations of seismic and geological-cross sections (C). The location of the study area is outlined by the red box (Sayed et al. 2023)

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Stratigraphy

The Pre-Miocene stratigraphic section of Bakr-Al Hamd ridge follows the general stratigraphic successions of the central GOS with the presence of several pay zones including the following at the pre-rift sequences, fractured carbonates of the Eocene Thebes Formation and sandstone of the Early Santonian Matulla, Turonian Wata, Cenomanian Raha Formations, the different members of the Early Cretaceous-Paleozoic Nubia Formation and the granitic basement rocks and its weathering cap (Fig. 4). Up-section syn-rift stratigraphic units lie on a variety of pre-rift strata that range in age from Oligocene to Paleozoic, Early Cretaceous or Precambrian basement. The existence of several unconformity events recorded in the syn-rift units is documented by Bosworth and McClay (2001).

Fig. 4
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Geological stratigraphic column penetrated at Bakr-Al Hamd oil fields

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Regionally, the Lower-Middle Miocene laterally facies changed from clastic dominant sequences in the Eastern margin of the Gulf to carbonate-dominated facies in the western side (study area location). These facies change has a direct impact on reservoir characteristics and the complexity that exists within syn-rift sequences (Fig. 5). Locally, in the Eastern part of the study area, the recorded penetrations by borehole data reveal that the carbonate reefal facies of Lower Miocene (Nukhul and Lower Rudeis Formations) are directly overlain by Serravallian Belayim Formation. In the Western direction, on the other hand, Kareem Formation was penetrated. The main stratigraphic focus of this study is the Lower Miocene (Nukhul-Lower Rudeis formations) carbonate reefal facies and Middle Miocene Belayim carbonate build-up (i.e., Nullipore). Moon and Sadek (1923) were the first authors to use the Nullipore term representing the sequences underlying the Evaporite group of the Middle to late Miocene age. This Nullipore rock is equivalent to Hammam Faraun Member of Belayim Formation (Stratigraphic Sub-Committee 1974). It is described as bioclastic lithology with frequent occurrence of red algae (Thiebaud and Robson 1979) that was developed in environmental conditions favorable for reef build-ups (warm shallow water).

Fig. 5
figure 5

Sketch section showing the regional lateral facies change of the Lower-Middle Miocene sequences from the eastern to the western margin of the central province of the GOS. The eastern side of the Gulf, which hosts the Belyaim land and Belayim marine oil fields, is dominated by clastic supply, whereas the western side, which hosts the Bakr and AL Hamd study areas, has been completely changed to carbonate facies. Not to scale. See Fig. 2 for the sketch location

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Dataset and methodologies

Dataset

The subsurface dataset used for this study comprises production history data, conventional well logs, borehole images, and 3D seismic data processed through post-stack time migration (PSTM). This is a part of the 203 km2 Bakr-Amer 3D seismic survey acquired in 1999 by Western Geco and 72.7 km2 of Al Hamd marine 3D seismic, it was processed by PGS in 2004. The maximum recorded time was 4000 ms with a line spacing of 25 m. The data quality is fair to good. It was acquired onshore using a vibroseis source and the offshore portion was acquired using an air gun with water depth ranging between 20 and 65 m. Faults and horizons interpretation was carried out on a workstation using Schlumberger’s Petrel® software.

Methodologies

The stratigraphic setting of the study area was examined focusing on the Miocene syn-rift units using electrical-log correlation collected from borehole data. Furthermore, well tops and fault cuts were reviewed for about two hundred well data. The seismic-to-well tie was carried out by using the available velocity data (vertical seismic profile).

Volume seismic attributes workflow was carried out on the original PSTM 3D seismic (ant-track-coherency and instantaneous frequency). The final volumes being used in the present study. Although the spectral decomposition method is relevant in seismic attribute workflow it is not applied in this study because it focuses on heterogenous carbonate reservoirs (Naseer 2021a, b, 2023; Okiongbo and Ombu 2019). Interpreted seismic profiles are displayed in normal SEG convention, with amplitude peaks shown in red and amplitude troughs shown in blue. The structural interpretation was conducted with a grid spacing of 5 lines (110 m) along the ENE–WSW in-lines NW–SE cross-lines and some random lines. Three key seismic horizons were selected for manual pick interpretation (1) Messinian Zeit Formation, (2) Serravallian Belayim Formation, and (3) Early Cretaceous Nubia A Formation. Time-structural maps for the mapped horizons were generated in addition to the detected detachment fault time surface map. For depth conversion, two controls were used to generate velocity maps: (1) a two-way-time structure contour map (based on time-depth pairs from the vertical seismic profile or VSP and validated by horizon criteria seismic response) and (2) formation well tops. To interpolate velocity between wells, the convergent algorithm method was used. All of the maps produced in the study area are displayed using the coordinate system, projection: Red Belt, Datum: old Egyptian 1907.

Previous model

The previously documented studies in the Bakr-Al Hamd field show two distinct Miocene carbonate productive oil fields of the Nullipore facies, delineated by a NW fault named F-1 and cross fault F-2, which is considered the Miocene carbonate reservoir play segment boundary for the B-H oil fields (Fig. 6). This is most likely due to unsuccessful wells located in that direction, and as a result, the previous tectonostratigraphic model assumed that wells X and Y were located at lagoonal facies, while well-Z was located at back reef facies (Fig. 6). Consequently, the stratigraphic position of reef distribution explained their classification as a dry well.

Fig. 6
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The previous model, combined structural map and facies distribution showing the location of B-H oil fields and unsuccessful wells location (A) and schematic cross-section (B)

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Tectono-stratigraphic re-evaluation of Bakr Al Hamd ridge

Stratigraphic analysis

First, an e-log correlation sample (Fig. 7) on the Miocene stratigraphic level between Bakr-well (producer), well-Z (unsuccessful), and Al-Hamd-well (producer) shows gamma-ray response and neutron-density curves. Integrated analysis with core data, ditch samples, and thin sections with the illustrated e-logs also confirmed that the deposition of Nukhul and Lower Rudeis reefal carbonate in Bakr field is overlain by Langhian Kareem shale, while the Serravallian Belayim Formation can be identified by its four members (Baba-Feiran-Sidri and Hammam Faraun). In contrast, well-Z penetrated a low-quality carbonate reservoir with a reduced vertical thickness, whereas in the Al Hamd field, these sequences laterally facies changed to a thick high-quality carbonate reservoir (200 m) of Lower to Middle Miocene age. On the other hand, observing the seismic signature expressing Al Hamd thick carbonate reservoirs is illustrated for allocating analogs if they exist (Fig. 8). This seismic phenomenon of mound shape defines the 300 m thick reef build-up.

Fig. 7
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E-log correlation between Bakr-well, Well Z, and Al Hamd well. See Fig. 6 for well location

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Fig. 8
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3D seismic section showing the Miocene carbonate reservoir seismic signature (mound shape detected due to reef build-up about 300 m thick) in Al Hamd field. See Fig. 3 for section location

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Structural analysis

The surface variance attribute map extracted near Middle Miocene Serravallian age demonstrates the presence of NE fault separating Bakr and Al Hamd oil fields as well as a series of NW faults to the south (Fig. 9). Seismic interpretation is shown in Figs. 10 and 11 demonstrates the detection of Bakr-AL Hamd boundary fault due the West and its associated footwall collapsing structures. Moreover, the detection of a low-angle fault separates the pre-rift and syn-rift sequences. The fault trajectories cut through the syn-rift units exhibit reversed dip polarities that sole down to the detected low-angle fault. Several rotated fault blocks were discovered in Bakr and Al Hamd intra-fields (Figs. 10, 11). It also revealed that carbonate facies developed on domino-style rotational fault blocks, with corresponding changes in accommodation space. Figure 12 depicts a balanced geological cross-section that was built to calibrate seismic interpretation using well data. The presence of a syn-depositional oblique-rift extensional fault influenced the carbonate development accommodation zone detected on the NW–SE geological cross section (Fig. 13). Furthermore, the interpretation of borehole images confirmed this contact as a low-angle fault-detachment surface, striking NNW–SSE and dipping 30° WSW at the Lower-Middle Miocene-Thebes Formations boundary, note truncation at possible fault cut, synthetic deformed bed (brown sinusoid), resistive fractures (cyan sinusoids) and high bed boundary dip (green tadpole) directly above resistive fractures above possible fault cut. dipping SW (Fig. 14).

Fig. 9
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Surface variance attribute map shows the detection of NE fault (yellow) separating Bakr and Al Hamd oil fields and a series of NW faults towards the south

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Fig. 10
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ENE-WSW oriented interpreted seismic section illustrates the interpreted low angle surface and associated faults. See Fig. 3 for section location

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Fig. 11
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ENE-WSW oriented interpreted seismic section illustrates the detected NW extensional faults (F-1, F-2, F-3, and Al Hamd boundary fault). See Fig. 3 for section location

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Fig. 12
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Geological cross-section-oriented E-W illustrating Bakr-Al Hamd fields structures. See Fig. 3 for section location

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Fig. 13
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NW–SE oriented geological cross sections passing through Bakr oil field, illustrated the NE oblique faults (note the Syn depositional fault at the SE). See Fig. 3 for section location

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Fig. 14
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Borehole image demonstrating the decollement fault presence (truncation at possible fault cut, synthetic deformed bed (brown sinusoid), resistive fractures (cyan sinusoids), and high bed boundary dip (green tadpole) directly above resistive fractures above possible fault cut). See Fig. 12 for well location highlighted with a star

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Dry well analysis

A dry well analysis scheme was used in the current study, followed by an examination of the four main factors that result in well failure if they are not exited: (1) trap, (2) reservoir, (3) pay zone, and (4) charge. The dry well analysis for the three wells (Fig. 15) reveals the following, (1) well-Y penetrated the Miocene carbonate reservoir through a fault cut, so, there is a trap and pay failure, (2) well Z penetrated only 24 m of low-quality Miocene carbonate reservoir through fault (Fig. 7), suggesting trap failure. While well Y is the most intriguing because it penetrated about 100 m of the carbonate reservoir, it is being evaluated as a potential well that needs to be revisited.

Fig. 15
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Inset map showing well-X, well-Y, and well-Z dry well analysis, and sketches showing the trajectory of the wells and penetrated Miocene section

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Subsurface mapping

To detect geometrical variation in the plan view, the detachment fault surface map is created. This detachment surface time map shows two antiformal features of different levels dissected by NW rift parallel faults (Fig. 16A). The isolated carbonate reservoir growth is attached to the detachment surface, where the low stand relief is documented due to the east and the high antiformal feature is located on the western side (Fig. 16A). The Pre-rifting sequences dominate the footwall of the detachment, with older stratigraphic cuts due west (Basement, Cretaceous-Paleozoic Nubia section is sub-cropping in the west, relative to the Eocene Thebes Formation in the east) (Fig. 16B). The structural depth map of the Late Cretaceous Nubia A Formation shows that a segmented western fault bound the area, transferred to NE oblique rift faults. The footwall tilted fault blocks due east, and several grabens were revealed separating Bakr and Al Hamd fields (Fig. 17). While on the stratigraphic level of the Serravallian Belayim Formation a series NE oblique faults separated Bakr and Al Hamd structural ridge (Fig. 18). Moreover, adding a series of rift parallel faults, F-1, F-2, F-3, and F-4 resulted in a clear southwestward dislocation of the old western gulf-parallel boundary fault F-1 of Al Hamd field (documented in the previous model Fig. 6) to the present shoreline. This resulted in adding subtle rooms for exploration potential, Finally, during the late Miocene, the structure intensity decreased at the stratigraphic level of Zeit Formation, detecting reverse faults developed above the detachment fault (Fig. 19).

Fig. 16
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Two-way time detachment fault surface map (A), and footwall stratigraphic cuts (B)

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Fig. 17
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Structural depth map on Early Cretaceous Nubia A Formation

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Fig. 18
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Structural depth map on Middle Miocene Serravallian Belayim Formation, see Fig. 12 for the highlighted faults trajectory

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Fig. 19
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Structural depth maps on Messinian Zeit Formation

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Discussion

The paper reveals the role played by extensional tectonics on carbonate platform development. The following part will uncover some debates argued in the presented model. The pre-rift syn rift contact in the Gulf of Suez is defined as an unconformity relationship (Said 1962; Evans 1988; Khalil and McClay 1998; Sharp et al. 2000; El Barkooky et al. 2006) unrelatedly to the time variability of stratigraphic units overlaying each other because extension rate of each fault block is inconsistent and consequent accommodation space filled by the sediment. This contact could be defined as a detachment extensional normal fault under certain conditions. Changing an unconformity contact to a low-angle fault has been documented in the literature. For example, Kemnitzer (1937), and Dibblee (1970) mapped the low-angle contact as unconformity but Davis (1980), Dokka (1986), and Gans et al. (1989) changed the interpretation to low-angle normal faults. Also, the mechanical argument for low-angle fault development was documented by Longwell (1945) Whereas the detachment is recognized along incompetent layers [e.g., shale or salt layers in the northern Gulf of Mexico (Worrall and Snelson 1989)]. However, along the Heart Mountain detachment, the existence of sliding along the Ordovician dolostones competent layers has been documented by Hauge (1990) and Pierce (1957). These examples generally involve only the upper few kilometers of the crust and are not accompanied by a coeval extension of the underlying continental basement (Anderson 1951; Wright and Troxel 1973; Davis and Coney 1979; Crittenden et al. 1980; Wernicke 1981; Armstrong 1982; Holm et al. 1993). Salim et al. (2016) documented the presence of a detachment fault at the adjacent South Bakr oil field. Moreover, ramp-flat-ramp fault geometry is observed in the surface outcrop at Sudr Chalk Formation located at Wadi Abu Khelifia western central margin of the GOS (Sehim 2017 personal communication) (Fig. 20).

Fig. 20
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Surface photograph for ramp-flat-ramp fault geometry in Sudr Chalk, Wadi Abu Khalifia, the western central margin of the GOS (Sehim 2017 personal communication)

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Recognition of detachment fault geometry and its influence on carbonate facies development accommodation space

Recognizing detachment faults is critical not only because the structural model changes above and below the detachment surface, but also because the geometrical pattern of such faults affects the sedimentation rate directly. The present work demonstrates the observation, interpretation, and confirmation of the detachment fault. The detachment fault most likely developed as a result of high-angle fault rotation and subsequent linkage between them (Fig. 21). The illustrated geometrical pattern of the decollement fault (Fig. 16), on the other hand, influences the accommodation space for reef growth. This explains the thickness, vertical and lateral facies variation observed between Bakr-Al Hamd oil fields (Fig. 7). The accommodation space expands as a result of the detachment fault soled down, and because this occurs in favorable conditions for reef formation, the maximum thickness developed above the maximum fault soled down (Figs. 11, 12). In contrast, thinning is found above the high relief of the fault surface. Furthermore, the difference in the depositional setting of Belayim facies exists in Bakr and Al Hamd fields indicating that the two areas were structurally distinct during Belayim deposition. The lateral facies change recognized in the Belayim Formation from neritic lagoonal evaporites deposited in Bakr field in the relatively high area to the west into shoal complex (Bioherm) littoral environment in Al Hamd field was caused by eustatic sea level change relative to extensional rotated fault blocks developed on the detachment fault hanging wall (Figs. 10, 11). Furthermore, facies and thickness relationships of Miocene carbonate units at Bakr-Al Hamd field indicate that differential motion of small blocks and movement on cross faults played an important role in controlling sedimentation. The reef types (Fig. 21) in this study are defined as a fringing reef in Bakr field, developed near shore, less than 500 m wide linear shaped of reduced thickness. Al Hamd carbonate build-up, on the other hand, is classified as a barrier reef with a width of more than 500 m. The intra-field between Bakr and Al Hamd, on the other hand, is of the patch reef variety (Fig. 22). This is supported by reactivated exploration drilling activity (Fig. 23) in the previously classified lagoonal facies area of low interest as a result of the failed well location. Well-A was recently announced as a discovery that penetrated a 200-m heterogeneous Miocene carbonate reservoir. Dolomitic limestone dominates the modified lithofacies, with fewer occurrences of proper limestone and argillaceous limestone (Fig. 24).

Fig. 21
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Block diagrams depict Miocene carbonate reef build-up over time. A During the early stage of rifting, there were two highs bounded by antithetic faults, at the early rifting stage the detachment fault developed probably as a result of the rotation of those two faults. In Bakr field the Eocene high partially submerged with seawater as it was running parallel to the shoreline while Al Hamd high was submerged with the seawater. B Later, the Miocene carbonate developed above the décollement surface with the existence of favorable environmental conditions and eustatic sea level

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Fig. 22
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A Cross-section diagram and B block diagram for reef type classification in the study area

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Fig. 23
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Surface attribute map from Middle Miocene time showing the Miocene reef types with blue polygons

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Fig. 24
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Interpreted seismic section-oriented SSE-NNW illustrating well-A recent discovery trajectory and seismic signature (A), and schematic cross-section showing the detected minor deformation (B). See Fig. 3 for section location

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Conclusions

  • The present study revealed the influence of extensional structure on the Miocene carbonate reefal reservoirs in Bakr and Al Hamd oil fields in the West Central Gulf of Suez.

  • The produced structural model documented the field boundary fault footwall collapsing structures and early Miocene detachment fault.

  • Facies and thickness relationships of Miocene carbonate strata at Al Hamd Bakr field indicate that differential motion of small blocks and movement on cross faults were important to controlling sedimentation.

  • The difference in the depositional setting of Servallian Belayim strata in Bakr and Al Hamd fields indicates that the two areas developed at different structural blocks and eustatic sea level changes during Middle Miocene Belayim deposition.

  • In Bakr field Belayim were deposited in relatively high areas to the west of the study area, in contrast, Belayim strata were deposited in relatively deeper water in Al Hamd area.

  • The reef types are identified as fringing reef developed at Bakr field, barrier reef growth at Al Hamd field, and patch reef occurrence at the intra-field between Bakr and Al Hamd fields.

  • The detected rotated fault blocks further to the southwest of Al Hamd field added several potential blocks to be tested. In 2021 and 2022 General Petroleum Company announced three discoveries in the intra-field between Bakr-Al Hamd fields penetrated about 200 m thick dolomitic limestone lithofacies.