Stochastic Reservoir Model for the First Eocene Reservoir, Wafra Field, Partitioned Neutral Zone (PNZ)

Meddaugh, W. Scott; Dull, Dennis W.; Griest, Stewart; Montgomery, Paul; McNaboe, Gerry

doi:10.1007/978-1-4020-3610-1_78

Cited by 2 publications

(4 citation statements)

References 4 publications

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“…As noted by Meddaugh et al 5 the bounding surfaces of the HFS in the First Eocene reservoir interval at Wafra field were identified by the following: (1) sub-aerial unconformity; (2) turn-around from progradation to transgression; (3) a lithofacies tract offset across a chronostratigraphic boundary, and (4) systematic changes in thickness and/or lithofacies proportion of cycles or cycle sets. The First Eocene has been subdivided into HFS that are bounded by hardgrounds, subaerial exposure surfaces, or lithofacies tract offset.…”

Section: Cycle Setmentioning

confidence: 97%

“…4). This early work was summarized by Meddaugh et al 5 The core descriptions for the 5 wells that were available in 2002 contained sufficient detail to construct the depositional framework and provide the basis for fieldwide stratigraphic correlation. The five core descriptions show numerous hardgrounds throughout the First Eocene reservoir interval.…”

Section: First Eocene Reservoir Sequence Stratigraphymentioning

confidence: 99%

“…The HFS is composed of genetically related cycles and cycle sets. 10 As noted by Meddaugh et al 5 , the cycle tops in the First Eocene reservoir interval were identified using the following criteria: (1) hardgrounds or erosional surfaces; (2) tidal flat mudstones (occasionally with algal laminations); (3) inner shelf peloidal or skeletal dolowackestones; (4) bedded or nodular gypsum associated with tidal flat and sabkha deposition, and (5) dolograinstones and grain-dominated dolopackstones. Note that the latter are mostly confined to the lower portion of the First Eocene reservoir interval.…”

Section: First Eocene Reservoir Sequence Stratigraphymentioning

confidence: 99%

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The Wafra First Eocene Reservoir Partitioned Neutral Zone (PNZ), Saudi Arabia and Kuwait: Geology, Stratigraphy, and Static Modeling

Meddaugh

Dull

Garber

et al. 2007

SPE Middle East Oil and Gas Show and Conference

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TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThe First Eocene reservoir at Wafra Field was discovered in 1954 and has produced about 290 million barrels of 17-19° API, high sulfur oil.The dolomite reservoir is Eocene/Paleocene age. The average porosity is 35% and the average permeability is 250 md over the gross interval. Well log and core plug porosity values over 45% are common and measured permeability values range up to 5000 md. The First Eocene reservoir has an average depth of about 1300 feet and a gross thickness of about 750 feet. The OOIP is about 9 billion barrels.The reservoir largely consists of dolomitized packstones and grainstones deposited under arid to semi-arid conditions on a shallow, very gently dipping, low to moderate energy inner shelf or ramp setting in a gently dipping, restricted ramp environment. The presence of some interbedded evaporites suggests restriction was occasionally sufficient for the development of hyper-saline lagoons and sabkhas. The shallowing-upward cycles are capped by mud-dominated rocks, hardgrounds and exposure surfaces that are correlative with gamma ray highs that can be easily correlated across the 20 km length of the field and are the basis for the current sequence stratigraphic interpretation.Several full field and small, highly detailed reservoir models have been generated using stochastic workflows to assist management of on-going primary development as well as two steamflood test/pilot projects. The reservoir models utilize the new stratigraphic framework and are constrained by over 285 wells with high quality porosity logs and six wells with high quality core descriptions and core plug data. Model properties were distributed by stratigraphic layer and constrained by layer-appropriate data (or transforms) and layer-appropriate semivariograms. The range parameter for the semivariograms models used in full field static models varied between 1100-2200 m with moderate anisotropy in the direction N120°E. Conversion Factors1 foot = 0.3048 meters 1 meter = 3.2808 feet 1 mile = 1.6093 km

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Section: Cycle Setmentioning

confidence: 97%

Section: First Eocene Reservoir Sequence Stratigraphymentioning

confidence: 99%

Section: First Eocene Reservoir Sequence Stratigraphymentioning

confidence: 99%

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The Wafra First Eocene Reservoir Partitioned Neutral Zone (PNZ), Saudi Arabia and Kuwait: Geology, Stratigraphy, and Static Modeling

Meddaugh

Dull

Garber

et al. 2007

SPE Middle East Oil and Gas Show and Conference

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“…The layer-specific correlation coefficients varied from À0.5 to À0.8. Additional details regarding the workflow and its application to this reservoir are provided by Meddaugh et al (2005a) and Meddaugh et al (2007). The use of petrophysically derived lithofacies as an additional constraint was investigated but not ultimately used because of a relatively low correlation between predicted and actual lithofacies in the validation wells.…”

Section: Static Modelmentioning

confidence: 99%

Probabilistic Forecasting and Model Validation for the First-Eocene Large-Scale Pilot Steamflood, Partitioned Zone, Saudi Arabia and Kuwait

Osterloh

Mims

Meddaugh

2013

SPE Reservoir Evaluation &Amp; Engineering

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The First-Eocene heavy-oil reservoir (1E) in the Wafra field is a candidate for steamflooding because of its world-class resource base and low-estimated primary recovery. However, industry has little experience in steamflooding carbonate reservoirs, which has prompted the staging of several 1E steamflooding tests, the latest of which is the large-scale pilot (LSP) started in 2009. To assist in facilities design, to help understand expected performance in a very heterogeneous reservoir, and to provide input to early-decision analyses, numerical thermal simulation was used to generate probabilistic forecasts. When adequate pilot history was available, the model was validated with probabilistic methods.The LSP model contained 1.5 million cells, which allowed the maintenance of adequate resolution and proper boundary conditions in the pilot area. Parallel computation enabled a probabilistic workflow to be implemented with this large thermal model.In this paper, we highlight the methodologies and inputs used to generate the probabilistic forecasts and validate the model. Major results of this work include the following: In contrast to many greenfield forecasts, the LSP forecasts were conservative, likely because of the unique aspects of the forecasting methodology, proper selection of uncertainty ranges, and the relatively high density of input data for model construction; wide variations in production metrics were forecast, indicative of a highly heterogeneous reservoir; results indicated that the validated model adequately captured the global or statistical pilot heterogeneity, enabling proper capture of steamflood flow/drainage mechanisms; and despite this heterogeneity, forecast oil-recovery levels were comparable with those observed in steamfloods in sandstone reservoirs.

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Stochastic Reservoir Model for the First Eocene Reservoir, Wafra Field, Partitioned Neutral Zone (PNZ)

Cited by 2 publications

References 4 publications

The Wafra First Eocene Reservoir Partitioned Neutral Zone (PNZ), Saudi Arabia and Kuwait: Geology, Stratigraphy, and Static Modeling

The Wafra First Eocene Reservoir Partitioned Neutral Zone (PNZ), Saudi Arabia and Kuwait: Geology, Stratigraphy, and Static Modeling

Probabilistic Forecasting and Model Validation for the First-Eocene Large-Scale Pilot Steamflood, Partitioned Zone, Saudi Arabia and Kuwait

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