Flow Unit Characterization of a Shallow Shelf Carbonate Reservoir: North Robertson Unit, West Texas

Davies, David; Vessell, R.K.

doi:10.2523/35433-ms

Cited by 8 publications

(5 citation statements)

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“…Conventional statistical regression has been done parametrically in the past, using linear or nonlinear models. A widely used approach is the Flow Units Method 4,7,8 . In this method the permeability is related to the porosity and the Flow Zone Indicator (FZI) as:…”

Section: Theorymentioning

confidence: 99%

A Method To Estimate Permeability on Uncored Wells Based on Well Logs and Core Data

Lacentre

Carrica

2003

SPE Latin American and Caribbean Petroleum Engineering Conference

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TX 75083-3836 U.S.A., fax 01-972-952-9435. AbstractReservoir description for simulation studies requires good knowledge of the permeabilities. Unfortunately, reliable permeability is only available from laboratory tests on cores, which are usually taken from a small percentage of the wells. Frequently, this information is extrapolated to calculate permeabilities all over the field, but the lack of enough data points usually causes unreliable predictions. We propose a method to estimate formation permeabilities from standard well logs and core data. The analysis includes a first step consisting of the interpretation of the petrophysics and a characterization in lithofacies, electrofacies and hydraulic flow units. This step involves the use of modern mathematical tools to rationally classify each reservoir region into a given (discrete) hydraulic flow unit. As a second step the core permeability data is mapped with the well log data using neural networks and the restrictions found on the first step of the analysis. This approach allows the use of continuous hydraulic flow unit values and reduces the error arising from the discrete zonation technique. Also, it overcomes the error coming from the mapping between log data and hydraulic flow units. The method should be applicable to any kind of reservoir as long as sufficient core and log data are available. The method assumes that the Carman-Kozeny equation holds for the reservoir rocks, which is a fairly reasonable assumption, and that the well logs available contain intrinsic information on tortuosity, sand size distribution, cementing characteristics, etc., which ultimately determine the flow performance of the rock. This hypothesis is usually strong because the available logs are not able to fully read the physical phenomena that cover the complex dynamics of the flow on the reservoir rocks. The method was tested using available core and log data in a sandstone formation in Chihuido de la Salina, Neuquen Basin, Argentina. Some core data points were not used to train the neural network and therefore useful for validation and comparison. In spite of the cited drawbacks, the method has shown to outperform both the standard regression techniques and the hydraulic flow units approach.

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Section: Theorymentioning

confidence: 99%

A Method To Estimate Permeability on Uncored Wells Based on Well Logs and Core Data

Lacentre

Carrica

2003

SPE Latin American and Caribbean Petroleum Engineering Conference

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“…To better understand the relationship between observed facies and production performance in the TXL South Unit Field, we developed a petrophysical or "rock-log" model using a methodology similar to previous studies. 7,10,11 The primary objective of the petrophysical study was to develop a robust model (i.e., calculation algorithm) that allowed us not only to identify rock type but also to quantify net pay, effective porosity, and absolute flow capacity from the geophysical well log response. Our rock-log model directly integrated porelevel geometric attributes with basic wireline log measurements.…”

Section: Petrophysical Studymentioning

confidence: 99%

“…The next stage of rock typing characterized plugs on the basis of pore geometry determined using petrographic analysis of thin sections (TS) and scanning electron microscopy (SEM) images. [10][11][12][13] Pore geometrical attributes included pore-body size, shape, and arrangement. We also integrated high- Core Porosity, percent Core Permeability, md pressure mercury-injection capillary pressures with SEM analysis of pore casts to further quantify the distribution of pore throat sizes.…”

Section: Petrophysical Studymentioning

confidence: 99%

Reservoir Characterization and Infill Drilling Study of a Low-Permeability Carbonate: An Evaluation of Blanket Versus Targeted Infill Drilling Strategies

Rushing

Blasingame

2003

SPE Annual Technical Conference and Exhibition

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TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThis paper presents the methodology and results of a reservoir characterization study of Clear Fork carbonates in the TXL South Unit Field located in Ector County, Texas. The principal objective of our study was to evaluate a targeted infill drilling strategy for future field development. Our study incorporated an integrated approach for which the primary evaluation tool was decline type curve analysis of well production data. The well performance analysis was both supplemented and complemented with petrophysical and geological studies, each representing different reservoir scales. On the basis of our study, we identified areas of the field with the highest reservoir quality and largest oil-in-place volume, thus identifying the areas of the field best suited for infill drilling.

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“…13 for reservoir characterization purposes. North Robertson Unit (NRU) is a heterogeneous, low permeability carbonate reservoir located in the Permian Basin of West Texas.…”

Section: Field Applicationmentioning

confidence: 99%

Swept Volume Calculations and Ranking of Geostatistical Reservoir Models Using Streamline Simulation

Idrobo¹,

Choudhary²,

Datta-Gupta³

2000

Proceedings of SPE/AAPG Western Regional Meeting

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TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractGeostatistical techniques are increasingly being used for modeling reservoir heterogeneity and assessment of uncertainty in performance predictions. Although a large number of stochastic reservoir models or realizations may be generated, in practice only a small fraction can be considered for comprehensive flow simulations. This can be done through a ranking process. Several papers have been published in the literature on ranking of realizations. However, a consistent and generally applicable set of criteria for model ranking still remains unclear.In this paper we propose a connectivity criterion based on the streamline time-of-flight and use this criterion to rank geostatistical realizations for detailed flow simulation purposes and risk assessment. Because time-of-flights reflect fluid front propagation at various times, the connectivity in the time-of-flight provides us with a direct measure of volumetric sweep efficiency for arbitrary heterogeneity and well configuration. We show that the proposed connectivity criterion exhibits strong correlation with waterflood recovery and thus, can be used for ranking stochastic reservoir models. Unlike permeability connectivity which is a static measure independent of the flow field, the time-of-flight connectivity rigorously accounts for the interaction between the flow field and the underlying heterogeneity.Our proposed approach has been applied to synthetic as well as field examples. Synthetic examples are used to validate the sweep efficiency calculations using the streamline time-of-flight connectivity criterion by comparison with analytic solutions and published correlations. These examples also demonstrate the superiority and effectiveness of the ranking criterion over existing methods. The field example is from the North Robertson Unit, a low permeability carbonate reservoir in west Texas. Our example includes multiple patterns consisting of 27 producers and 15 injectors and illustrates the feasibility of the approach for large-scale field applications.

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Flow Unit Characterization of a Shallow Shelf Carbonate Reservoir: North Robertson Unit, West Texas

Cited by 8 publications

References 0 publications

A Method To Estimate Permeability on Uncored Wells Based on Well Logs and Core Data

A Method To Estimate Permeability on Uncored Wells Based on Well Logs and Core Data

Reservoir Characterization and Infill Drilling Study of a Low-Permeability Carbonate: An Evaluation of Blanket Versus Targeted Infill Drilling Strategies

Swept Volume Calculations and Ranking of Geostatistical Reservoir Models Using Streamline Simulation

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