Supratidal (sabkha) to intertidal (microbial mat), and lowermost intertidal to shallowsubtidal (peloid-skeletal tidal flat) environments were studied along the Abu Dhabi coastline in the vicinity of Al-Qanatir (Al-Rufayq) Island. A transect from land to sea displays the following classic examples of supratidal to shallow-subtidal facies belts:(1) Inner, upper sabkha (upper supratidal), buckled polygonal halite crust displaying teepee structures; (2) Stranded beach ridges, forming low-relief topographic highs paralleling the coastline that are mainly composed of cerithid gastropods; (3) Outer, upper sabkha (upper supratidal), buckled polygonal halite crust displaying teepee structures; (4) Middle sabkha (middle supratidal), whitish anhydrite polygons on surface; (5) Lower sabkha (lower supratidal), soft, shiny surface due to sparkling gypsum crystals (gypsum mush); (6) Upper intertidal, thin, leathery, crinkled or crenulated microbial mat; (7) Middle intertidal, blistered microbial mat and pinnacle or domed microbial mat; (8) Lower intertidal, thick, smooth polygonal microbial mat and tufted or cinder-like microbial mat; (9) Lowermost intertidal to shallow-subtidal, peloid-skeletal tidal flat (lagoonal and shallow tidal-channel/tidal-creek deposits) displaying cerithid and littorinid gastropod grazing-traces, Skolithos-type burrows, and eroded wave ripples.The stenohaline bryozoan species Disporella sp., which has not been recorded previously from the United Arab Emirates, was found within a thin channel lag deposit of the outer, upper sabkha environment. Significant amounts of dolomite were found within a subsurface crinkly-laminated microbial mat (middle sabkha environment). The fine-crystalline dolomite displays subhedral to euhedral dolomite rhombs embedded in an organic matrix. The formation of dolomite is interpreted to be related to sulphate reducing microbial organisms which form the widespread microbial mat along the Abu Dhabi coastline.Radiocarbon dating of 15 samples (10 hardground samples, 3 microbial mat samples, and 2 samples from anhydrite-dominated layers) show an age range from ca 3500 uncalibrated 14 C yr BP (outer, upper sabkha environment: subsurface hardground, seaward of stranded beach ridges) to ca 900 uncalibrated 14 C yr BP (intertidal environment: subsurface microbial mat); thereby supporting the seaward progradation of the facies belts since the last Holocene sea-level highstand (formation of cerithid gastropod stranded beach ridges). An anhydrite layer within aeolian deposits (inner, upper sabkha environment: landward of stranded beach ridges) showed a radiocarbon age of the host sediment of ca 12,900 uncalibrated 14 C yr BP, corresponding to Pleistocene dune deposits, pre-dating the Holocene flooding event. The distribution of radiocarbon ages indicates a complex stratigraphic history in which chronostratigraphic time lines clearly cross-cut depositional lithofacies and diagenetic boundaries. This is significant in that depositional lithofacies and diagenetic facies are commonly used i...

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Hydrocarbon gas injection has proven to be one of the most efficient Enhanced Oil Recovery (EOR) methods, especially for tight and heterogeneous reservoirs with light to medium API oil, where water flooding is expected to be inefficient. Asphaltene precipitation and deposition, however, might occur due to pressure and fluids compositional changes with the gas injection. This complex phenomenon requires experimental and numerical investigation to understand the conditions at which flow impairment due to asphaltene formation damage may occur, resulting in lowering well flow capacity and in turn lower ultimate oil recovery. In this experimental study, low permeability carbonate rock core samples were flooded with hydrocarbon gas under reservoir conditions. The floods were conducted on core samples of two different lengths representing two different rock types based on average rock permeability and Pore Throat Size Distribution (PTSD). Additionally, these core samples were flooded at two different operating conditions to mimic the average reservoir and the wellbore flowing pressure conditions. As a prelude to these experiments, Asphaltene Onset Pressure (AOP) and Asphaltene Onset Concentration (AOC) of the oil under study with the injection gas were established through NIR, SARA and Titration analysis. Flow impairment due to formation damage by asphaltene precipitation and deposition was analyzed through permeability measurements before and after gas flooding. In all cases permeability reduction was observed. Permeability reduction was found to be function of rock types, reservoir pressure, and length of composite core samples. We assume that pore throat bridging by the larger size asphaltene particles caused higher permeability reduction in the samples of poorer rock types. Experiments conducted at lower pressures showed more damage. This is consistent with the lower AOC at lower pressure. Longer core samples give more time for asphaltene flocculation resulting in more asphaltene formation damage and more permeability reduction. Scanning Electron Microscopic (SEM) images of core plugs before and after the gas flooding process were found to be not conclusive with respect to direct detection of asphaltene deposition in the core samples and further work is planned to positively identify asphaltene deposition in the rock samples.

The aim of this paper is to provide an insight on the usage of unmanned aerial vehicles (drones) for capturing 3D photorealistic images of geological outcrops which can be used as digital analogs during 3D geological modelling. Recognizing the potential of the use of drones in many other fields has opened the doors for an endless variety of applications in the geoscience world as well. Specifically, in geological mapping and 3-D modeling activities, the use of these technologies can be seen as a cost-effective method of quickly and accurately surveying, mapping and capturing surface geological phenomena and processes that were more difficult and expensive for been surveyed in the past. Combining aerial and ground photography acquisitions, the image of geological outcrops can be captured and modelled in 3D using photogrammetry techniques, generating Digital Elevation Models (DEM). With DEM the users can perform measurements in multiple azimuths and compare and overlay geological, geophysical and petrophysical data at different scales and obtain multi-point statistics (MPS) for MPS modelling or conventional spatial statistical information for variogram analysis. Jumping ahead from the past where data was used for only qualitative comparison through pictures, the outcrop data can be used directly as a cloud of points to be used as 3-D wireframes into modelling software for enhancing reservoir architecture procedures (designing vertical layering schemes on grids) capturing reservoir heterogeneities at different scales. The creation of digital outcrop models using drone technologies is a cost effective solution to introduce the advantage of the field observations into more accurate subsurface models. The advantage of incorporating outcrop information into the geological modelling workflow is the ability to understand, based on direct observations of the complexity of the geological drivers, which one plays the major control on the property distribution and flow processes in the subsurface.