Estimating spatial distributions of heterogeneous subsurface characteristics by regionalized classification of electrofacies

Moline, Gerilynn R.; Bahr, Jean M.

doi:10.1007/bf02083565

Cited by 20 publications

(10 citation statements)

References 8 publications

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“…The above indicator approach is similar to an approach known as regionalised classi®cation (Bohling, 1997;Harf and Davis, 1990;Moline and Bahr, 1995). Regionalised classi®cation is, in fact, nothing more than the interpolation to unobserved sites of the inputs to or the outputs from some traditional classi®er applied to sparse data.…”

Section: Alternative Smoothing Approachesmentioning

confidence: 99%

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Geostatistical classification for remote sensing: an introduction

Atkinson

Lewis

2000

Computers & Geosciences

259

128

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Section: Alternative Smoothing Approachesmentioning

confidence: 99%

“…The work on regionalised classi®cation of Harf and Davis (1990), Moline and Bahr (1995) and Bohling (1997) (among others) illustrates clearly that there are many possible spaces in which the smoothing can take place. These include (see Fig.…”

Section: Selecting An Appropriate Spacementioning

confidence: 99%

Geostatistical classification for remote sensing: an introduction

Atkinson

Lewis

2000

Computers & Geosciences

259

128

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“…It represents a multivariate extension of the geostatistic function (semi-variogram) and is usually applied in geological sciences (e.g. Moline & Bahr 1995). Here the auto-D 2 was used to estimate the observational window (Platt & Denman 1975) to calculate the D 2 to the centroid function.…”

Section: Detection and Characterisation Of Disturbancesmentioning

confidence: 99%

Effect of meteorological and hydrographic disturbances on the microplankton community structure in the Ría de Vigo (NW Spain)

Nogueira¹,

Ibañez²,

Figueiras³

2000

Mar. Ecol. Prog. Ser.

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The relationships between meteorological and hydrographic disturbances and microplankton community structure and organisation were investigated in the Ría de Vigo, an estuarine ecosystem affected by coastal upwelling. The frequency and duration of sampling (ca twice per week from September 1990 to May 1992) are appropriate to reveal the impact of disturbances in the context of the seasonal cycle. Perturbations were identified statistically and related to recognisable meteorological and hydrographic processes that are expected to influence microplankton dynamics. According to the frequency of disturbances (between 8 and 14 yr -1 ) the ecosystem could be classified as intermediate-frequency disturbed in relation to the microplankton community organisation timescales. Meteorological and thermohaline disturbances promoted changes in microplankton community structure (disjunctions). The time-series of thermohaline properties, a proxy for allogenic processes related with mixing regimes and estuarine circulation, was the best indicator of changes in community structure: 15 out of the 21 disjunctions (ca 70%) coincided with thermohaline disturbances. Disturbances of the nutrient fields were related to allogenic forcing but also, markedly during the productive season, to re-structuring of the microplankton community. They pointed out autogenic community-driven processes. Microplankton assemblages revealed by the species-oriented ordination technique were interpreted in terms of the replication strategies: well-defined groups of competitor (C), disturbance-tolerant ruderal (R) and stress-tolerant (S) species were discerned. At a seasonal time-scale, succession progressed according to the sequence from r-to K-selection strategies. C-species dominated spring assemblages, during the period of transient thermoclines, while Sspecies contributed more to summer assemblages, when the thermocline was fully developed and the ecosystem was under nutrient stress. R-species showed an intermittent pattern and their relative abundance increased when environmental variability was more acute, during the winter and spring to summer (clear-water phase) transition. The regime of allogenic disturbances operating at intermediate frequency during the productive season allowed the maintenance of relatively high microplankton diversity at the functional (assemblage) level: all types of replication strategies were present during summer and early autumn. The results support the applicability of the intermediate disturbance hypothesis (IDH) to microplankton community structure in the Ría de Vigo.KEY WORDS: Disturbances · Microplankton community structure · Replication strategies · Intermediate disturbance hypothesis (IDH) · Ría de VigoResale or republication not permitted without written consent of the publisher

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“…Most commonly, permeability is estimated from various well logs using either empirical relationship or some form of statistical regression: parametric or non-parametric. 7,8,[9][10][11][12][13][14] The objective of this paper is to further improve permeability predictions in heterogeneous reservoirs through a combination of electrofacies characterization, non-parametric regression techniques and the integration of dynamic data from DST. Also, significant uncertainty exists in the determination of irreducible water saturation and cementation factor in these models.…”

Section: Introductionmentioning

confidence: 99%

Integrated Permeability Modeling Using Wireline Logs, Core and DST Data in a Deepwater Reservoir

Taware

Sinha

et al. 2008

All Days

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Reservoir characterization requires accurate estimates of permeability. The commonly used porosity-permeability transforms are often inadequate as permeability is also a function of clay distribution, sorting, pore connectivity, tortuosity and variations in other petrophysical properties. More robust permeability estimation can be made by integrating multiple logs in the transform instead of just porosity.This paper deals with a novel technique for deriving permeability by correlating multiple well logs with core permeability using non-parametric regression methods. First, we classify the well log data into electrofacies based on the 'similarity' of their response. This electrofacies classification does not require any artificial subdivision of the data population but follows naturally based on the unique data values reflecting minerals and lithofacies. A combination of principal component and model-based cluster analysis are used to characterize the electrofacies. Secondly, we apply a non-parametric regression technique to predict permeability using well logs within each electrofacies. The main advantage of this technique is that it is primarily data-driven as opposed to model driven and does not require a priori specification of functional forms, which makes conventional multiple regressions difficult and often biased.The proposed technique was used in a deepwater reservoir system consisting of thick massive sand beds along with thinly bedded sand-shale sequences. The work flow consists of electrofacies identification, facies-wise permeability transform generation, calibration with DST data, and finally permeability population in the geological model using cloud transforms and Sequential Gaussian Simulation (SGS). The permeability transforms generated from core and well log data were validated via blind tests whereby we predicted permeability in another cored well that was not included in the correlation. For further validation, we also used the transform-derived permeabilities in analyzing the DST results in a blind well where a laminated sand section was tested. A reasonable match of the permeability-thickness product was observed. Finally, the permeability transforms were integrated into a 3-D geologic modeling using SGS and cloud transform. It was observed that our approach correctly captured the porosity-permeability scatter in the geologic model for various facies groups.

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Estimating spatial distributions of heterogeneous subsurface characteristics by regionalized classification of electrofacies

Cited by 20 publications

References 8 publications

Geostatistical classification for remote sensing: an introduction

Geostatistical classification for remote sensing: an introduction

Effect of meteorological and hydrographic disturbances on the microplankton community structure in the Ría de Vigo (NW Spain)

Integrated Permeability Modeling Using Wireline Logs, Core and DST Data in a Deepwater Reservoir

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