Отправлено: 11.03.15 09:27. Заголовок: An integrated and quantitative approach to petrophysical heterogeneity

An integrated and quantitative approach to petrophysical heterogeneity
Peter J.R. Fitch a, *, Mike A. Lovell b, Sarah J. Davies b, Tim Pritchard c, Peter K. Harvey

a b s t r a c t
Exploration in anything but the simplest of reservoirs is commonly more challenging because of the
intrinsic variability in rock properties and geological characteristics that occur at all scales of observation
and measurement. This variability, which often leads to a degree of unpredictability, is commonly
referred to as “heterogeneity”, but rarely is this term defined. Although it is widely stated that heterogeneities
are poorly understood, researchers have started to investigate the quantification of various
heterogeneities and the concept of heterogeneity as a scale-dependent descriptor in reservoir
characterization.
Based on a comprehensive literature review we define “heterogeneity” as the variability of an individual
or combination of properties within a specified space and/or time, and at a specified scale. When
investigating variability, the type of heterogeneity should be defined in terms of grain e pore components
and the presence or absence of any dominant features (including sedimentological characteristics
and fractures). Hierarchies of geologic heterogeneity can be used alongside an understanding of measurement
principles and volumes of investigation to ensure we understand the variability in a dataset.
Basic statistics can be used to characterise variability in a dataset, in terms of the amplitude and
frequency of variations present. A better approach involves heterogeneity measures since these can
provide a single value for quantifying the variability, and provide the ability to compare this variability
between different datasets, tools/measurements, and reservoirs. We use synthetic and subsurface
datasets to investigate the application of the Lorenz Coefficient, DykstraeParsons Coefficient and the
coefficient of variation to petrophysical data e testing assumptions and refining classifications of heterogeneity
based on these measures.

Marine and Petroleum Geology 63 (2015) 82e96