TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThis paper describes a systematic and logical workflow for characterizing a UAE outcrop of the Upper Thamama reservoir.This integrated workflow uses sequence stratigraphy, geologic modeling, and fluid flow simulation and was used as a tool for training early-career UAE geoscientists and engineers. Although the primary focus of the paper is on the mechanics of geologic modeling with principles applicable to UAE fields, the integrated workflow covers the entire spectrum from rock characterization all the way to flow simulation.Outcrop analogs are a valuable source of data for reservoir characterization. They are particularly useful for visualizing interwell variability because subsurface wellbores represent discrete widely spaced data. In other words, outcrops provide the continuous, large-scale coverage of a seismic line and provide the fine-scale resolution of core measurements. Modeling input parameters such as lateral and vertical continuity (variogram range), object dimensions (aspect ratios), detailed reservoir architecture (layering), facies relationships, and the nature and extent of diagenetic features can be observed and measured.To better understand reservoir properties of the Upper Thamama producing zones in Abu Dhabi, a geologic model was developed from descriptions of time-equivalent, analogous outcrops in the Emirate of Ras Al-Khaimah. Parasequences, maximum flooding surfaces, sequence boundaries and lithofacies were described in four measured sections. Porosity measurements derived from logs, core porosity, and core permeability data from an Abu Dhabi oil field were applied to similar lithofacies observed in outcrop. These subsurface data were used in the outcrop 3D model to more precisely reflect subsurface reservoir behavior because outcrops in the UAE experienced a significantly different burial history relative to the subsurface reservoirs. 1For the stratigraphic interval studied in outcrop (i.e., Upper and Lower Kharaib Formation), four composite reservoir facies (three permeable and one "dense") adequately described the flow behavior. These reservoir facies were modeled using Petrel 2 software and were scaled up into a simulation model using ExxonMobil's next generation reservoir simulator, EM power .™ ,3 Multiple scenarios, including various injection patterns, scaleup methods, and locations of thin, highpermeability streaks, were investigated. Results mimicked known behavior in analogous producing fields and the process of going from rock data to simulation provided a useful training tool for reservoir characterization methods and techniques.
TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractA new sequence stratigraphic framework is proposed for the Lower Cretaceous Kharaib Formation (Barremian and Lowermost Aptian) of the United Arab Emirates. This framework is based on the integration of core and well-log data from Abu Dhabi oil fields with outcrop data from Wadi Rahabah, Ras Al-Khaimah (U.A.E.).The Kharaib Formation is part of the late transgressive sequence set of a second-order supersequence, built by two third-order composite sequences.Fourteen fourth-order parasequence sets build into two third-order composite sequences and show predominantly aggradational and progradational stacking patterns, typical of greenhouse cycles.On the basis of faunal content, texture, sedimentary structures, and lithologic composition, eleven reservoir lithofacies and eight non-reservoir "dense" lithofacies are identified from core.These same lithofacies are also identified in time-equivalent rock exposures studied in Wadi Rahabah. The analyzed lithofacies range from open platform, lower ramp to restricted platform subtidal to intertidal environments.Intensively bioturbated wackestone and packstone, and interbedded organic-and siliciclastic-rich limestone characterize the three so-called dense zones (Lower, Middle, and Upper Dense Zone). Locally, mud-cracks, blackened grains, and rootlets are observed. The two reservoir zones (Lower and Upper Kharaib Reservoir Unit) correspond to the late transgressive and, dominantly, highstand systems tracts characterized by parasequence sets that show shallowing-upward trends from open platform, burrowed skeletal wackestone to skeletal, peloidal packstone and algal, coated-grain grainstone/rudstone, and rudist, algal floatstone/rudstone.Well-developed Thalassinoides firmgrounds (Glossifungites surfaces) indicate temporary cessation in sedimentation and cap several parasequence sets and parasequences. Stylolitic intervals within the reservoir units predominantly correspond to major facies changes related to third-, fourth-, and fifth-order sequence boundaries, parasequence set boundaries, and parasequence boundaries.In outcrop, low-angle clinoforms that cannot be seen in core data are observed within the highstand systems tract of the upper third-order composite sequence (Upper Kharaib Reservoir Unit). Integration of subsurface and outcrop data leads to more insightful and realistic geological models of subsurface stratigraphy. Christian J. Strohmenger (ADCO), L.J. (Jim) Weber (ExxonMobil Exploration Co.), Ahmed Ghani, Michel Rebelle (ADCO),
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