Link Between Microporous Limestones and Elastic Properties in Tight Carbonates. A Case Study from the Lower Arab Formation Upper Jurassic, Onshore United Arab Emirates

Perière, Matthieu Deville de; Foote, Alexander; Bertouche, Meriem; Shah, Razza; al-Darmaki, Fatima; Ishaq, Wala Bin

doi:10.2118/188944-ms

Cited by 2 publications

(1 citation statement)

References 23 publications

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“…Conceivably, the veins are tension gashes formed with the stylolites. Similar observations were previously reported (Nelson, 2001), including from the lower Arab-D in the Emirates (De Periere et al, 2017).…”

Section: Development Of Veins and Stylolitessupporting

confidence: 92%

New scaling of fractures in a giant carbonate platform from outcrops and subsurface

Al-Fahmi

Hooker

Al-Mojel

et al. 2020

Journal of Structural Geology

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We scale properties of fractures in the Late Kimmeridgian carbonate platform of the Arabian Shelf from outcrop and subsurface strata. The platform is flat-lying undeformed except from low-relief anticlines and domes, at which the strata hosts the world's most prolific petroleum reserves. The strata exhibit stylolites and veins, besides the dominant fractures. The fractures are opening-mode, steep, and forming major sets of NW-SE and NE-SW orientations. Faults are uncommon. Fracture abundance varies significantly across the platform, but it is constrained spatially by inherent variation in mechanical stratigraphy and temporally by anticlinal growth and isotope geochemistry. In early burial stages, the platform strata were slightly deformed by bed-parallel stylolites and mutually crosscutting veins. The strata fracturing increased by the anticlinal growth in the Late Cretaceous. Fracture spacing is an average of 2m in the horizontal-bedded outcrops in Central Arabia and 0.30m in the equivalent subsurface in a dome in Eastern Arabia. The dome is an end member in the deformation spectrum of the platform interior, with up to c. 5° structural dip and 2% dilational strain expressed in the doming and a few major faults. This finding indicates that carbonate platforms can reach fracture oversaturation under such a subtle tectonic extension.

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Section: Development Of Veins and Stylolitessupporting

confidence: 92%

New scaling of fractures in a giant carbonate platform from outcrops and subsurface

Al-Fahmi

Hooker

Al-Mojel

et al. 2020

Journal of Structural Geology

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Microporosity of the Shuaiba Formation: The Link Between Depositional Character and Diagenesis in Sharjah, United Arab Emirates

Phukan

Siddiqi

Robert³

2021

Day 1 Mon, November 15, 2021

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Objectives/Scope This study focuses on assessing the uncertainties related to sedimentological heterogeneity and the diagenetic variability within the gas-condensate reservoirs of the Shuaiba Formation, Sharjah, United Arab Emirates. Methods, Procedures, Process For characterizing the sedimentology of the Shuaiba Formation, a lithofacies scheme has been developed on the basis of Dunham's (1962) and Embry & Klovan classification (1971). The lithofacies are grouped on the basis of their genetic relationships which also correspond to their depositional environment, and are designated as lithofacies associations. A pore-scale fabric/textural investigation was completed using conventional thin-section microscopy and Scanning Electron Microscopy (SEM). Results, Observations, Conclusions The Shuaiba sediments are characterized by skeletal-rich wackestone/packstones to floatstones deposited in an inner ramp setting. The stacking pattern of the inner ramp deposits define broad third order trends observed across the studied field.These trends are relatable to the regional sequence stratigraphic framework of Sharland et al. (2001). In higher order sequences, lateral variations in lithology occur, defining the reservoir heterogeneity, which are most likely forced by topographic/hydrodynamic variation as well as sea level changes. Reservoir quality distribution is controlled by various factors, including the depositional texture and allochem assemblage (abundance, type, and size). Diagenetic alteration of the textures played an important role in determining overall reservoir quality. The pore enhancing phases are defined by dissolution events, where later stage dissolution was the dominant phase to enhance micropores and also to create meso- to macropores which partially to completely negated the effect of previous cementing phases. In these Shuaiba deposits, the porosity comprises common matrix-hosted as well as grain-hosted micropores along with variably distributed intraparticle and rare mouldic meso- to macropores. The measured porosity ranges from very poor to moderate (0.5-17%) while permeability is very low to low (<0.001-1.49 mD). The detailed petrographic analysis highlighted that changes in micritic fabric shows a variation in the reservoir properties. From SEM observations, it was noted that microcrystalline calcite crystals of polyhedral to sub-rounded morphologies with intercrystalline contacts ranging from facial to sub-punctic, which display relatively a good microporosity developement, whereas crystals that show anhedral compact character with coalescent/fused intercrystalline contacts are rarely associated with any microporosity. Novel/Additive Information In addition to SEM characterization, porosity data and elastic properties (e.g., Young's moduli) generated from the interpretation of the well-log data, were used to investigate the prospective relationship between the microporous carbonates and elastic properties. The comparisons highlight that an increase in porosity values results in a decrease of Young's moduli values, thereby reflecting a decrease in the stiffness of the rock. On the other hand, the increase in porosity maybe linked to the evolution of anhedral, compact, micritic fabric to polyhedral/sub-rounded micritic fabric. The understanding of this relationship provides a powerful tool to be utilized in reservoir architecture prediction based on integrating the sedimentological framework and diagenetic overprint.

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Link Between Microporous Limestones and Elastic Properties in Tight Carbonates. A Case Study from the Lower Arab Formation Upper Jurassic, Onshore United Arab Emirates

Cited by 2 publications

References 23 publications

New scaling of fractures in a giant carbonate platform from outcrops and subsurface

New scaling of fractures in a giant carbonate platform from outcrops and subsurface

Microporosity of the Shuaiba Formation: The Link Between Depositional Character and Diagenesis in Sharjah, United Arab Emirates

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