Seismic Sequence Stratigraphy in Mapping Complex Reservoir Reef Build-up Geometries (Offshore Abu Dhabi field)

Bellah, Samir; Shateri, Abdulla Abdul Qader Al; Kumpas, Michael G.

doi:10.2118/137660-ms

Cited by 3 publications

(1 citation statement)

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“…Substantially, this picture can be applied for both R5 and R4, where we have maximum proliferation of reef facies and lithology changes ref (2). Blocks movement and reactivation (shearing), stress regime changes and development of local stress components led to creation of a complex fractures network associated with the macro faults system.…”

Section: Conceptual Modelingmentioning

confidence: 96%

An Integrated Approach to Build 3D Fracture Model

Bellah¹,

Hosany²,

Najia³

et al. 2012

All Days

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An offshore Abu Dhabi carbonate oil field which was discovered in 1969 and put on production in 1985. The field produces from a reefal limestone formation deposited in the middle cretaceous. The field is characterized by good reservoir properties in the rudest banks well developed in the northern part of the field. Soon after production starts, wells water cut gradually increased to reach 50% within 4-5 years with drastic decline in oil production. Horizontal drilling was implemented with an objective of increasing well exposure to reservoir, reducing drawdown and as such combating water coning/channeling phenomena. Although oil production from horizontal wells was substantially improved, water production trend and production decline, however, did not change in most of the cases. Reservoir heterogeneities, such as fractures and facies distribution, are believed to be main contributors to a water coning/ channeling phenomena and to the escalation of water production trends. Therefore, understanding of geological, petrophysical, properties of the formation is the corner stone for, controlling water production problems and hence improving reservoir performance. In this contest, the operating company decided in 2006 to acquire 3D seismic to improve the field imaging and embarked in intensive well data gathering program including, FMI, coring, VSP and PLT measurements to improves the knowledge about the reservoir. This paper will illustrate an integrated approach to build a 3D fracture model of Reservoir-A using a comprehensive full set of geological drivers obtained from seismic attributes, core and logs data which may control and explain the fracture occurrence in the reservoir. The model was used to enhance the history match accuracy and help also to assess new potential ideas for future development.

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Section: Conceptual Modelingmentioning

confidence: 96%

An Integrated Approach to Build 3D Fracture Model

Bellah¹,

Hosany²,

Najia³

et al. 2012

All Days

Self Cite

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Ground-penetrating radar imaging of Albian rudist buildups, central Texas

et al. 2015

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Rudist buildups are important reservoirs in many Cretaceous fields in the Middle East, but they are generally near or below seismic resolution. The dimension, shape, and architecture of rudist buildups can be assessed using outcrop, although only partly so because of pseudo-2D observations of geobodies intersecting with the outcrop. We used ground-penetrating radar to enhance our understanding of the shape, dimension, and architecture of Albian rudist buildups in two outcrops in Texas. In the Lake Georgetown spillway, caprinid rudist buildups are 10–30 m wide and 2–7 m high. They are elliptical with an aspect ratio of as much as 1.7. They show no or very little flank development. The older buildup exposed in the Red Bluff Creek area displays 10- to 25-m-wide and 5- to 10-m-high in situ caprinid rudist mound core accumulations with as much as 100-m-wide reworked flanks in the shallower part of the depositional profile. Downdip along the depositional profile, caprinid buildups are 5–20 m wide and 3–7 m high with no flank debris. The buildups in the Lake Georgetown area have similar architecture and comparable size with the downdip buildups exposed in Red Bluff Creek. These buildups were compared with other outcropping Albian buildups in Texas that have different sizes, shapes, and stratigraphic architecture to provide dimensional data that could be used in subsurface reservoir modeling, either for calibrating variogram ranges or to build training images. The rudist buildups exposed in Texas are an order of magnitude smaller than those present in the subsurface in the Middle East, but they have comparable stratigraphic architecture. The size difference might be the result of subsurface buildups being mapped using well-log or core correlations or seismic extractions that cannot resolved at that scale of heterogeneity.

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Improved Reservoir Characterization of Flow Connectivity in Complex Carbonate Field, Using DepoGrid Model

Bellah

Fletcher

Gomes

et al. 2019

Day 3 Wed, November 13, 2019

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The Mishrif formation in Abu Dhabi comprises progradational shelf margin facies. The western platform sediments are characterized by stacked clinoforms of clean high energy carbonates, with generally good reservoir properties at the top deteriorating gradually toward the west flank. In contrast in the east the formation is thicker and characterized by more differentiated, coarsening, shoaling- upwards sequences. High quality reservoir facies occur only near the prograding shelf edges. The reservoir in this study had finely layered pillar grid models of the field using onlap and offlap layering to capture the vertical property heterogeneity and layering within the clinoforms implied by the depositional environment. However, this grid structure posed challenges for flow simulation as there were unphysical barriers and connections across the clinoform boundaries caused by the pinching out layers at boundaries between clinoform units. By construction, in a depogrid each clinoform may be independently gridded with coordinate lines that do not need to be continuous through the vertical extent of the reservoir. Layers within a sequence can truncate arbitrarily against bounding discontinuities since the cells are polyhedral and the grid globally unstructured. Therefore, an evaluation of the depogrid cut-cell grid was undertaken for the reservoir. A volume-based model was constructed using horizon surfaces and fault surfaces extracted from the pillar grid model, and the depospace transform calculated. The depogrid was created using the same areal resolution as the pillar grid. The layer parameters were set to give approximately the same number of layers in each zone as the pillar grid. The rock type base properties from the pillar grid were upscaled onto the depogrid, in the interest of time, to populate the static depogrid model. Reservoir fluid properties, relative permeability, and capillary pressure curves were taken from existing simulation models of the field. A high-resolution reservoir simulator was then run on the depogrid model. Run time comparisons of the pillar and depogrid simulations were made The evaluation concluded that the cut-cell stratigraphically layered depogrid provided a more geologically consistent representation of the complex stacked clinoform structural elements and required significantly fewer grid layers to achieve the required vertical resolution. The depogrid simulations could represent the expected connectivity for flow. Improved run times were observed

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Seismic Sequence Stratigraphy in Mapping Complex Reservoir Reef Build-up Geometries (Offshore Abu Dhabi field)

Cited by 3 publications

References 1 publication

An Integrated Approach to Build 3D Fracture Model

An Integrated Approach to Build 3D Fracture Model

Ground-penetrating radar imaging of Albian rudist buildups, central Texas

Improved Reservoir Characterization of Flow Connectivity in Complex Carbonate Field, Using DepoGrid Model

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