Suez Rift Research Articles

Structural constraints on the groundwater regime of the Cretaceous aquifers in Central Sinai, Egypt

The Lower Cretaceous aquifer is one of the most important water bearing formations not only in Sinai but also in the Middle East because of its high hydraulic parameters and good water quality. This aquifer is dominated by a thick sequence of well sorted and permeable sandstones The Lower Cretaceous aquifer is generally crossed by two main E–W trending, down to the north normal right-lateral oblique-slip faults; the Ragabet El-Naam Fault (RANF) to the south and Minsherih-Abu Kandu Shear Zone (MAKZ) further north.In Central Sinai, the water flow pattern and hydrochemistry of the Lower Cretaceous aquifer are controlled by the fault-fold patterns. Across the RANF the water flow is retarded behind the fault zone and deviates toward its central segment where the groundwater spills-out northward at Nekhel City. In contrast, the MAKZ defines a barrier for the northward flowing groundwater where the Lower Cretaceous aquifer south of the fault is blocked by the Upper Cretaceous to Eocene limestone and shale to the north. The water type changes across the fault zones from meteoric water to water of marine origin at the RANF and north of MAKZ respectively with sporadic occurrences of old marine water types limited to NW-trending structural lows. Generally the northward flow pattern of the Lower Cretaceous aquifer shows an eastward deviation to Gulf of Aqaba-Dead Sea rift and southwestward deviation to Gulf of Suez rift. Such deviations are controlled by the fault patterns characterizing north and west Sinai provinces.

Inland jump of the Arabian northwest plate boundary from the Levant continental margin to the Dead Sea Transform

While the breakup of Arabia and Africa began in the early Oligocene, the northwestern boundary of the Arabian Plate along the Dead Sea Transform (DST) formed 10–15 Myr later (early–middle Miocene). During the early stage of breakup the Red Sea Rift continued propagating northwestward, forming the Suez Rift. The present ∼45° northward twist of the plate boundary from the Red Sea toward the Gulf of Eilat (Aqaba) still did not exist. What happened at the northern tip of the Suez Rift at that time? How was strain distributed to its surroundings, and where did the plate boundary continue from there? Here we describe an abandoned segment of the Arabian northwestern plate boundary that extended from the northern tip of the Suez Rift northeastward, along the Levant margin. Seismic data collected offshore Israel support a subsurface, deep‐rooted fault zone running along the base of the continental slope. These faults indicate Oligocene transpressional lateral shearing. We propose that during the early stage of continental breakup a left‐lateral strike‐slip motion of ∼10 km took place along this embryonic plate boundary. Such deep‐rooted tectonism implies that unlike the passive situation of the Israel‐Sinai continental margin witnessed presently and before the Oligocene, during the early stage of the Africa‐Arabia breakup this part of the continental margin was reactivated. We further suggest that the inland jump of the plate boundary toward the DST was not immediate and that during the transitional period the Israel‐Sinai triangular block was an independent subplate with deformation all around it.

Evolution and structural style of relay zones in layered limestone–shale sequences: insights from the Hammam Faraun Fault Block, Suez rift, Egypt

A fully breached relay zone was investigated to gain insight into relay growth and breaching in layered limestone–shale sequences. Associated fracture patterns were analysed to gain a qualitative understanding of fault- and damage-zone evolution and fracture-related fluid conduits associated with fault overlap zones. Internally, the relay zone is characterized by dilatant brittle deformation in mechanically strong limestone of the stratigraphically upper part of the ramp, and down-dip shear along extensional detachments in stratigraphically lower and mechanically weak shale layers at the base. The linking damage zone is characterized by multi-directional fracture patterns, including fracture corridors at high angles to the main (bounding) faults. The causal relationship between fault growth and the complex fracture patterns lies in the interaction and progressive rotation of the local stress fields of overlapping or linking fault segments. Increasingly complex fracture patterns may therefore be expected during growth and linkage of fault segments. The observed fracture patterns, in concert with complex juxtaposition relations generated by dipping relay beds, indicate that fault linkage points in carbonate rocks represent localized conduits for cross-fault as well as vertical along-fault fluid flow. These have implications for hydrocarbon migration pathways and for reservoir connectivity during production from carbonate reservoirs.

Structural Architecture for Development of Marginal Extensional Sub-Basins in the Red Sea Active Rift Zone

This paper presents a robust kinematic model that describes northern Red Sea and Gulf of Suez rifting and the development of marginal extensional half-graben sub-basins (ESB). A combination of Landsat Enhanced Thematic Mapper Plus (ETM+) and structural data was used to provide model constraints on the development of rift segments and ESB in the active rift zones. Structural analysis shows rotation and change in strike of rift-bounding faults. The model describes the northern Red Sea region as a poly-phase rift system initiated by late Oligocene (30 - 24 Ma) orthogonal rifting and the development of marginal ESB (now inland ESB), followed by oblique rifting and flank uplift during the early Miocene (24 - 18 Ma). The oblique rifting fragmented the rift depression into segments separated by oblique-slip accommodation within reactivated Pan-African (ca. 600 Ma) fracture zones, resulting in the development of antithetic faults and an en-echelon distribution of inland ESB. The current phase of rifting was instigated by the development of the Dead Sea Transform in response to increased northeasterly extension during the middle Miocene (ca. 18 Ma). The model explains the widening of the Red Sea rift during the last phase more than the Gulf of Suez rift by developing more antithetic faults and formation of offshore ESB, and deepening the rift depression.

Late Oligocene–Early Miocene Nukhul Sequence, Gulf of Suez and Red Sea

ABSTRACT Egypt’s Late Oligocene–Early Miocene Nukhul Formation was deposited during the earliest geological evolution of the Gulf of Suez and Red Sea Rift System. In this paper the formation is cast as a depositional sequence based on published sections, and correlated across the Gulf of Suez and northern Red Sea. The resulting correlations indicate that deposition was initiated in local grabens by the oldest continental clastics of the lower member of the Nukhul Formation, the Shoab Ali Member. The member overlies the Suez Rift Unconformity, a term proposed for the entire Red Sea. Although this member can attain a thickness of ca. 1,000 ft (305 m) locally in grabens, it is generally absent over horsts. Sedimentary facies of the member are interpreted as indicating an initial alluvial-fluvial setting that evolved to an estuarine and coastal setting. The upper part of the Nukhul Formation records a regional shallow-marine transgression, which can be subdivided into three correlative Upper Nukhul members. These sediments are absent over the highest paleo-horsts, but reach up to 900 ft (275 m) in thickness in grabens. In the southern Gulf of Suez the Ghara Member represents the Upper Nukhul members. In places it consists of four cycles, each of which starts with an anhydrite bed and is overlain by deposits of mixed lithology (sandstone, marl, and limestone). The four cycles are interpreted as transgressive-regressive subsequences that can be correlated across ca. 60 km in the Gulf of Suez. The Ghara Member correlates to Saudi Arabia’s Yanbu Formation, which consists of massive salt in wells drilled on the Red Sea coastal plains. The Yanbu Salt is dated by strontium-isotope analysis at ca. 23.1–21.6 Ma (earliest Aquitanian). The Nukhul Formation is capped by the Sub-Rudeis Unconformity or correlative Rudeis Sequence Boundary, and overlain by the Rudeis Formation. The Nukhul Formation is here proposed as the Nukhul Sequence and defined in the Wadi Dib-1 Well, wherein it consists of Nukhul subsequences 1 to 10 (in descending order, ranging in thickness between 33–84 m). The lower six Nukhul subsequences 10 to 5 are characterized by shale-to-sandstone cycles of the Shoab Ali Member, and the upper four are represented by the cycles of the Ghara Member. The 10 subsequences are interpreted as tracking the 405,000 year eccentricity signal of the Earth’s orbit and to span ca. 4.0 million years between ca. 25.0 and 21.0 Ma.

Nukhul Formation in Wadi Baba, southwest Sinai Peninsula, Egypt

ABSTRACTThe Nukhul Formation is the oldest syn-rift rock unit in the Gulf of Suez rift system in Egypt. The age of the formation is inadequately resolved by biostratigraphy and it is generally assigned to the Lower Miocene by stratigraphic position. For this study a surface section was measured and sampled at Wadi Baba, located in the southwestern Sinai Peninsula. It yielded 17 planktonic foraminiferal species and 17 foraminiferal benthonic species. The planktonic foraminiferal assemblage was used to divide the formation into two planktonic foraminiferal zones: (1) Globigerina ciperoensis Zone (O6) of Late Oligocene Chattian age; and (2) Globigerinoides primordius Zone (M1) of Early Miocene Aquitanian age. The two zones coincide with depositional sequences: (1) Chattian Lower Nukhul Sequence, with its upper boundary coinciding with the Chattian/Aquitanian (Oligocene/Miocene) boundary; and (2) Aquitanian Upper Nukhul Sequence, with its upper sequence boundary coinciding with the Aquitanian/Burdigalian boundary.

Quantification and Prediction of the 3D Pore Network Evolution in Carbonate Reservoir Rocks

This study presents an integrated approach that allows the reconstruction and prediction of 3D pore structure modifications and porosity/permeability development throughout carbonate diagenesis. Reactive Pore Network Models (PNM-R) can predict changes in the transport properties of porous media, resulting from dissolution/cementation phenomena. The validity and predictability of these models however depend on the representativeness of the equivalent pore networks used and on the equations and parameters used to model the diagenetic events. The developed approach is applied to a real case of a dolostone rock of the Middle East Arab Formation. Standard 2D microscopy shows that the main process affecting the reservoir quality is dolomitisation, followed by porosity enhancement due to dolomite dissolution and secondary porosity destruction by cementation of late diagenetic anhydrite. X-ray μ -CT allows quantifying the 3D volume and distribution of the different sample constituents. Results are compared with lab measurements. Equivalent pore networks before dolomite dissolution and prior to late anhydrite precipitation are reconstructed and used to simulate the porosity, permeability characteristics at these diagenetic steps. Using these 3D pore structures, PNM-R can trace plausible porosity-permeability evolution paths between these steps. The flow conditions and reaction rates obtained by geochemical reaction path modeling can be used as reference to define PNM-R model parameters. The approach can be used in dynamic rock typing and the upscaling of petrophysical properties, necessary for reservoir modeling.

Exploration and assessment of the geothermal resources in the Hammam Faraun hot spring, Sinai Peninsula, Egypt

The tectonic position of Egypt in the northeastern corner of the African continent suggests that it may possess significant geothermal resources, especially along its eastern margin. The most promising areas for geothermal development in the northwest Red Sea-Gulf of Suez rift system are located where the eastern shore of the Gulf of Suez is characterized by superficial thermal manifestations, including a cluster of hot springs with varied temperatures. Magnetotelluric and gravity-reconnaissance surveys were carried out over the geothermal region of Hammam Faraun to determine the subsurface electric resistivity and the densities that are related to rock units. These surveys were conducted along profiles. One-dimensional (1D) and two-dimensional (2D) inversion model techniques were applied on the MT data, integrating the 2D inversion of gravity data. The objectives of these surveys were to determine and parameterize the subsurface source of the Hammam Faraun hot spring and to determine the origin of this spring. Based on this data, a conceptual model and numerical simulation were made of the geothermal area of Hammam Faraun. The numerical simulation succeeded in determining the characteristics of the heat sources beneath the Hammam Faraun hot spring and showed that the hot spring originates from a high heat flow and deep ground water circulation in the subsurface reservoir that are controlled by faults. These studies were followed by an assessment of the geothermal potential for electric generation from the Hammam Faraun hot spring. The value of the estimated potential is 28.34 MW, as the reservoir is assumed to be only 500 m thick. This value would be enough for the desalination of water for both human and agricultural consumption.

The Lower Paleozoic rock units in Egypt: An overview

Lower Paleozoic rocks are exposed in various regions of Egypt (south central Sinai, north Eastern Desert and southwest Western Desert), in addition to occurring in the subsurface such as north Western Desert and the Gulf of Suez. The Lower Paleozoic rocks in Egypt include surface and subsurface rock units of formational status. The surface rock units are the Taba, Araba and Naqus formations. The subsurface rock units include the Shifa, Kohla and Basur formations. The Infracambrian Taba Formation has been discovered recently in the outcrops of the southeast central Sinai in the Taba-Ras El-Naqab area. It is missing and/or not recognized in the subsurface. The Taba Formation consists mainly of reddish brown, unfossiliferous gravelly fine- to medium-grained kaolinitic sandstones and subordinate horizons of paleosols. The Cambrian Araba Formation and its subsurface equivalent (the Shifa Formation) are essentially composed of reddish brown, fine-grained laminated sandstone and siltstone with abundant Skolithos and Cruziana sp. In contrast, the Ordovician–Silurian Naqus Formation and its subsurface equivalents (the Kohla Formation and Basur Formation) are mainly composed of white, unfossiliferous, cross-bedded, medium- to coarse-grained sandstones with haphazardly distributed pebbles and cobbles. Sedimentological analysis indicates that the Araba Formation and its subsurface equivalent were deposited in a marginal-marine environment, whereas the Naqus Formation and its subsurface equivalents were laid down in a fluvio-glacial environment. Integrated stratigraphic and sedimentological studies of the Lower Paleozoic rocks permit reconstruction of the paleogeography of Egypt at that time. Egypt has been largely controlled since the Cambrian by the pre-existing structural framework of the pre-Phanerozoic basement rocks inherited from the Late Proterozoic Pan-African event. Additionally, sedimentation processes were controlled during Cambro-Ordovician times by tectonic movements, whereas glacio-eustatic control predominated during the Late Ordovician–Silurian Period. These studies suggest that most areas of Egypt were exposed lands with episodically transgression by epi-continental seas related to the paleo-Tethys. These lands formed a part of a stable subsiding shelf at the northern Gondwana margin.

The linkage between fault throw and footwall scarp erosion patterns: an example from the Bremstein Fault Complex, offshore Mid‐Norway

AbstractStudies of normal fault systems in modern extensional regimes (e.g. Basin and Range), and in exhumed, ancient rift basins (e.g. Gulf of Suez Rift) have shown a link between the evolution of fault‐related footwall topography and associated erosional drainage systems. In this study, we use 3D seismic reflection data to image the footwall crest of a gravity‐driven fault system developed during late Middle Jurassic to Early Cretaceous rifting on the Halten Terrace, offshore Mid‐Norway. This 22‐km‐long fault system lacks significant footwall uplift, with hangingwall subsidence accommodating throw accumulation on the fault system. Significant erosion has occurred along the length of the footwall crest and is defined by 96 catchments characterized by erosional channels. These erosional channels consist of small, linear systems up to 750 m long located along the front of the fault footwall. Larger, dendritic channel systems extend further back (up to 3 km normal to fault strike) into the footwall. These channels are up to 7 km long, up to 50 m deep and up to 1 km wide. Fault throw varies along strike, with greatest throw in the centre of the fault decreasing towards the fault tips; localized throw minima are interpreted to represent segment linkage points, which were breached as the fault grew. Comparison of the catchment location to the throw distribution shows that the largest catchments are in the centre of the fault and decrease in size to the fault tips. There is no link between the location of the breached segment linkage points and the location and size of the footwall catchments, suggesting that the first‐order control on footwall erosion patterns is the overall fault‐throw distribution.

Nubia-Arabia-Eurasia plate motions and the dynamics of Mediterranean and Middle East tectonics

SUMMARY We use geodetic and plate tectonic observations to constrain the tectonic evolution of the Nubia–Arabia–Eurasia plate system. Two phases of slowing of Nubia–Eurasia convergence, each of which resulted in an ∼50 per cent decrease in the rate of convergence, coincided with the initiation of Nubia–Arabia continental rifting along the Red Sea and Somalia–Arabia rifting along the Gulf of Aden at 24 ± 4 Ma, and the initiation of oceanic rifting along the full extent of the Gulf of Aden at 11 ± 2 Ma. In addition, both the northern and southern Red Sea (Nubia–Arabia plate boundary) underwent changes in the configuration of extension at 11 ± 2 Ma, including the transfer of extension from the Suez Rift to the Gulf of Aqaba/Dead Sea fault system in the north, and from the central Red Sea Basin (Bab al Mandab) to the Afar volcanic zone in the south. While Nubia–Eurasia convergence slowed, the rate of Arabia–Eurasia convergence remained constant within the resolution of our observations, and is indistinguishable from the present-day global positioning system rate. The timing of the initial slowing of Nubia–Eurasia convergence (24 ± 4 Ma) corresponds to the initiation of extensional tectonics in the Mediterranean Basin, and the second phase of slowing to changes in the character of Mediterranean extension reported at ∼11 Ma. These observations are consistent with the hypothesis that changes in Nubia–Eurasia convergence, and associated Nubia–Arabia divergence, are the fundamental cause of both Mediterranean and Middle East post-Late Oligocene tectonics. We speculate about the implications of these kinematic relationships for the dynamics of Nubia–Arabia–Eurasia plate interactions, and favour the interpretation that slowing of Nubia–Eurasia convergence, and the resulting tectonic changes in the Mediterranean Basin and Middle East, resulted from a decrease in slab pull from the Arabia-subducted lithosphere across the Nubia–Arabia, evolving plate boundary.

Determining the uniqueness of best-fit trishear models

We show the application of a simulated annealing algorithm to trishear inverse modeling. The algorithm traverses the parameter space in search for best-fit models without being trapped in local minima, and thus sampling for more possible solutions globally. Simulated annealing is a robust and efficient technique to determine the uniqueness of best-fit trishear models; the spread of possible trishear models that can fit a structure. We first apply the algorithm to a decameter-size, contractional fault-propagation fold in west-central Taiwan, for which there is an exceptional exposure of pre-growth and growth strata. Simulated annealing shows that even for this complete fold dataset with low uncertainties, there is a range of models and fault slip/uplift histories that can fit the data, with the consequent implications for the assessment of seismic hazard. We then apply the algorithm to a kilometer-size, extensional fault-propagation fold, the Hadahid monocline, Gulf of Suez Rift, Egypt. In this monocline there is only surface coverage in the footwall anticline areas and the algorithm was used to delimit the range of possible models that can fit the data and their uncertainties, thus avoiding biases in the interpretation. Simulated annealing suggests that the along-strike structural variability of the monocline can result from along-strike variability in fault slip, fault propagation to fault slip ratio and depth of fault nucleation. Both examples illustrate the benefits of searching for a possible range of models rather than a precise best-fit model when modeling fault-propagation folds. In an attempt to understand which parameters control fault development, and also how the spread of possible solutions varies with fold growth, we apply the algorithm to four sequential stages of a published, analog clay model of an extensional forced fold. The inversions of the natural examples and the analog model suggest that the spread of the possible models is a manifestation of the data uncertainties, the suitability of the trishear model, fold evolution, and rock mechanical properties.

A preliminary regional geothermal assessment of the Gulf of Suez, Egypt

The tectonic setting of Egypt, in the northeastern corner of the African continent, suggests that it may possess significant geothermal resources, especially along its eastern margin. The most promising areas for geothermal development in the NW Red Sea-Gulf of Suez rift system are locations along the eastern shore of the Gulf of Suez that are characterized by surface thermal manifestations, including a cluster of hot springs with varied temperatures. The Gulf of Suez region is one of the most interesting geothermal areas in Egypt because of the high temperatures of its springs. Geothermal studies were performed based on bottom-hole temperature logs of 103 offshore oil wells in the Gulf of Suez. The eastern margin of the Gulf of Suez, especially in the vicinity of hot springs, is characterized by high temperature gradients and heat flow values of more than 100 mW/m 2. Geophysical studies, which characterized the gravity and aeromagnetic signatures of the Gulf of Suez, were used to investigate the origin of the high heat flow and to constrain the depths of the heat sources in the hottest areas. Based on these data, conceptual and numerical models of hydrothermal systems were developed of the Hammam Faraun and Hammam Musa hot springs, which are the hottest springs in Egypt. The modeling results show that the origin of the high heat flow is the uplifted basement rocks.

Conceptual model and numerical simulation of the hydrothermal system in Hammam Faraun hot spring, Sinai Peninsula, Egypt

The tectonic position of Egypt in the northeastern corner of the African continent suggests that it may possess significant geothermal resources, especially along its eastern margin. The most of the thermal springs in Egypt are located along the shores of Gulf of Suez and Red Sea. These springs are probably tectonic or nonvolcanic origin associated with the opening of the Red Sea—Gulf of Suez rifts, where the eastern shore of the Gulf of Suez is characterized by superficial thermal manifestations including a cluster of hot springs with varied temperatures. Hammam Faraun area consists of the hottest spring in Egypt where the water temperature is 70°C. Conceptual as well as numerical models were made on the Hammam Faraun hot spring based on geological, geochemical, and geophysical data. The models show that the heat source of the hot spring is probably derived from high heat flow and deep water circulation controlled by faults associated with the opening of the Red Sea and Gulf of Suez rifts.

Calcimicrobe tubules in uppermost Jurassic Arab-A carbonates of Saudi Arabia

ABSTRACT Uppermost Jurassic carbonates from the Arab-A Member of the Arab Formation in the subsurface of eastern Saudi Arabia reveal hollow, intertwined, locally bifurcating, microtubules consisting of a chain-like, uniserial series of inaperturate, stacked, concavo-convex crescentic chambers tentatively assigned to Gahkumella sp. Previously confined to the Oxfordian of North America, and possibly the Lower Cretaceous of Oman, this is believed to be the first observation of such forms in uppermost Jurassic carbonates. The carbonates consist of a lower, transgressive, ooid-foraminiferal lithofacies and an upper, regressive, stromatolite-ostracod lithofacies of which the microtubules are developed in the latter. Comparison of these structures with fossil and Recent cyanobacterial microborings and Oxfordian calcimicrobial tube-like forms suggests probable cyanobacterial affinity. Despite their very limited stratigraphic extent, they may contribute to improving mouldic microporosity of the Arab-A carbonate reservoir.

Reconstructing an extreme flood from boulder transport and rainfall–runoff modelling: Wadi Isla, South Sinai, Egypt

The Wadi Isla drainage basin, a narrow steep bedrock canyon and its tributaries, rises near the highest elevations of the Precambrian Sinai massif on the eastern margin of the tectonically active Gulf of Suez rift. The basin area upstream from the mountain front is 191 km 2 and downstream the wadi crosses a broad alluvial plain to the Red Sea. Stream-transported boulders within the lower canyon (up to 5 m in diameter) and in a fan downstream indicate extremely high competence. In one reach, a 60-m-long boulder berm, ranging in height from 3 to 4 m, lies along the southern wall of the canyon and contains boulders 2–3 m in diameter. Boulder deposits beyond the mouth of the canyon generally appear to be less than several metres thick and are composed of imbricated, well-sorted boulders. The last flood that deposited these boulders is believed to have been a debris torrent with a low content of fines. Mean intermediate diameter decreases from about 1.5 m just beyond the mouth of the canyon, where the channel width expands to 300 m, to about 0.5 m downstream to the point at which the valley is no longer confined on its south side. Using the empirical formula of Costa (1983), these clasts represent velocities decreasing from about 6.5 m s − 1 to 3.7 m s − 1 . Flood velocity and discharge were also calculated within the canyon, using Costa's (1983) method and by the Manning equation. Parameters for the calculation include a channel width of 65 m, flow depth of 3.5 m (average height of the boulder berm), an average slope of 0.038 and a roughness coefficient of 0.06. The resulting values include a velocity range between 6.8 m s − 1 and 7.3 m s 1 and a corresponding discharge range of ∼ 1550 m 3 s − 1 to 1660 m 3 s − 1 . A lower limiting discharge of 1320 m 3 s − 1 was obtained with an assumption of critical flow conditions. The boulder fan is much coarser than the older alluvial plain sediment, suggesting an increase in flood magnitudes in more recent times — perhaps in response to renewed uplift of the mountain front and/or climate change. A calibrated rainfall–runoff model was developed using SWAT to estimate modern flood discharges in Wadi Isla. The magnitude of discharge from 1998–2006 did not exceed 500 m 3 s − 1 . Artificial precipitation amounts (90 and 150 mm) were used to extrapolate from recent rainfall amounts to the amount of rainfall needed to produce a discharge range of 1320 m 3 s − 1 to 1660 m 3 s − 1 . Results show that rainfall must range between ∼ 102 mm and 125 mm to produce this discharge.

Fault seal prediction of seismic-scale normal faults in porous sandstone: A case study from the eastern Gulf of Suez rift, Egypt

A study of normal faults in the Nubian Sandstone Sequence, from the eastern Gulf of Suez rift, has been conducted to investigate the relationship between the microstructure and petrophysical properties of cataclasites developed along seismic-scale faults (slip-surface cataclasites) and smaller displacement faults (deformation bands) found in their damage zones. The results help to quantify the uncertainty associated with predicting the fluid flow behaviour of seismic-scale faults by analysing small faults recovered from core, a common procedure in the petroleum industry. The microstructure of the cataclasites was analysed as well as their single-phase permeability and threshold pressure. Faulting occurred at a maximum burial depth of ∼1.2 km. The permeability of deformation band and slip-surface cataclasites varies over ∼1.5 orders of magnitude for a given fault. Our results suggest that the lowest measured deformation band permeabilities provide a good estimate for the arithmetic-mean permeability of the major slip-surface cataclasites. This is because the cataclastic permeability reduction is mostly established early in the deformation history. Stress at the time of faulting rather than final strain appears to be the critical factor determining fault rock permeability. For viable predictions it is important that the slip-surface cataclasites and deformation bands originate from the same host. On the other hand, a higher uncertainty is associated with threshold pressure predictions, as the arithmetic-mean slip-surface cataclasite threshold pressure exceeds the highest measured deformation band threshold pressure by at least a factor of 4.

Multiple-scale facies and reservoir quality variations within a dolomite body – Outcrop analog study from the Middle Triassic, SW German Basin

This study focuses on a porous dolomite body in the proximal part of an epeiric carbonate ramp (Triassic Muschelkalk, South German Basin), analogous to hydrocarbon-bearing dolomite reservoirs in the Middle East (e.g. Khuff and Arab Formations). The dolomite body is made up of shoal, lagoonal and peritidal facies types and is built by a three-fold hierarchy of cycles (3rd-order to 5th-order). The best reservoir quality occurs in finely crystalline lagoonal dolo-mudstones (mean: K = 37.8 mD; φ = 20.2%) with micro-intercrystalline and vuggy porosity. Coarsely crystalline, shoal-related dolo-grainstones show variable reservoir potential (mean: K = 30.1 mD; φ = 4.4%) due to late diagenetic modification. Reservoir quality significantly decreases in the non-dolomitized foreshoal section (mean: K = 4.5 mD; φ = 3.6%). Stratigraphically, the most porous dolomite occurs in the upper regressive portion of the 3rd-order cycle. Reservoir quality progressively decreases towards the limy bottom of the section. Outcrop mapping showed high lateral continuity for the distribution of facies types and poroperm values on the scale of several 10s of meters. Within correlated 5th-order cycles, considerable facies and poroperm heterogeneity is already observed on the 100s of meters-scale. On a 1000s of meters-scale, the facies and lithology distribution is controlled by the geometry of a gently inclined carbonate ramp. During regression, a progradational pattern is recognized, marked by a basinward migration of backshoal facies and a down-dip decrease of dolomite body thickness. Lithology, facies and poroperm data from outcrops and cores were used for 3D-modeling with the software Petrel. The modeled variations in the poroperm distribution are consistent with the degree of heterogeneity expected for a combination of laterally persistent lithology and highly variable facies. Results of this study may help to better understand the reservoir heterogeneity of inner ramp dolomite bodies and can be applied to improve characterization and modeling of similar dolomite reservoirs.

Arab women managers and identity formation through clothing

PurposeThe purpose of this paper is to explore how Arab women managers construct their social identities through the meanings they ascribe to their clothing while pursuing managerial careers.Design/methodology/approachAn interview‐based qualitative approach is adopted for describing the meanings that the United Arab Emirates national women managers give to their clothing.FindingsThis paper identifies multiple coexisting identities in Arab women pursuing managerial careers. While the contradiction is found in the identity as a woman and as a manager, the normative dimensions of identity formation such as being a Muslim and an Emirati serve as enhancing for women's gendered managerial identity.Originality/valueThe value of this paper is twofold: first, contributes to the knowledge of the topic of Arab women in management which is understudied in academia; second, it particularly sheds light how women managers meaningfully use symbols, such as dress, to construct and perform gender realities in a career context.

High-fidelity walkaround VSP anisotropy analysis

Optimization of reservoir development and management requires not only the correct placement of wells but also the monitoring of fluid-drainage patterns. Knowledge of the fracture patterns in any given field is critical to the success of the optimization process because they are conduits for the fluid flow. Saudi Aramco has recently completed the acquisition and processing of a walkaround VSP survey in the Haradh Field to map fluid pathways within the Arab Formation. The survey is in an area known for premature water-flood front advancement and uneven sweep through a system of open and partially healing fractures. The primary objective of the VSP survey therefore is to determine which seismic attributes can be related to the presence of the fractures. In this paper, we describe the data quality and amplitude normalization undertaken to minimize the overburden footprint to obtain an estimate of the fracture-induced traveltime, polarization direction, and amplitude anisotropy.