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Ouvrages

A Geoscientist's Guide to Petrophysics

Bernard Zinszner, François-Marie Pellerin

Geoscientists and Engineers taking an interest in Petrophysics, are struck by the contrasting treatment of the Physics Aspects and the Geology Aspects. In most publications, the Physics Aspect prevails. The rock itself is considered as a black-box whose microscopic structure is briefly described as a model sometimes remote from reality.
But if we are to scale up isolated petrophyscial observations to an entire oil reservoir or an aquifer, it is essential to implement the powerful extrapolation tool of geological interpretation. This is clearly based on a good understanding of the relations between the petrophysical parameters studied and the petrological characteristics of the rock considered.
This Geological approach of Petrophysics is at the heart of our project.

The book is divided into two sections of different size:
The first section (by far the largest) describes the various petrophysical properties of rocks. Each property is defined, limiting the mathematical formulation to the strict minimum but emphasising the geometrical and therefore petrological parameters governing this property. The description of the measurement methods is restricted to an overview of the principles required for good communication between the geoscientist and the laboratory petrophysicist. For each property, we detail one or two aspects of the relations between petrophysics and geology (e.g. the porosity/permeability relations in carbonate rocks or irregular water tables and stratigraphic traps).

The second section concentrates on methodological problems and concerns, above all, the representativeness of the measurements and the size effects. The notions of Representative Elementary Volume, Homogeneity, Anisotropy, Rock Type, etc. provide a better understanding of the problems of up-scaling (Plug, Core, Log Analysis, Well Test). Lastly, we provide a description of several Porous Network investigation methods: Thin section, Pore Cast, Visualization of capillary properties, X-ray tomography.


Acknowledgements	V
Foreword ( PDF - 380 Ko )	VII
Nomenclature	XI
Unit conversion factors	XVII
Table of contents ( PDF - 400 Ko )

PART 1
PETROPHYSICAL PROPERTIES AND RELATIONS WITH PETROLOGY

Chapter 1-1

Calculation of Fluid Volumes In Situ (Accumulations): Static Properties

1-1.1	Porosity, Mineralogy of the Solid Phase and Compressibility	3
	1-1.1.1 Porosity: definitions (connected, occluded, effective porosity, etc.)	3
	1-1.1.2 Porosity measurement principles	5
	1-1.1.3 Clay porosity	12
	1-1.1.4 Order of magnitude of porosity in geomaterials	20
	1-1.1.5 Solid phase density and mineralogy	26
	1-1.1.6 Effect of stresses on porosity, Compressibility	39

1-1.2	Capillary Pressure in Case of Perfect Wettability	52
	1-1.2.1 Definition of perfect wettability and capillary pressure	53
	1-1.2.2 Capillary pressure curve	56
	Figure 1-1.32 Example showing the location of the non-wetting fraction trapped by imbibition in natural porous media ( PDF - 1.5 Mo )
	1-1.2.3 Capillary phenomena in soils ( PDF - 3.6 Mo )	64
	1-1.2.4 Capillary pressure curve measurement principle: Restored states, Centrifuge, Mercury Porosimetry	73
	Figure 1-1.46 Example of application of porosimetry to the quantitative description of the porous space of sandstone of increasing clay content; (four plates) ( PDF - 2 Mo )
	1-1.2.5 Processing of capillary pressure data	94
	1-1.2.6 Location of fluids in oil and gas reservoirs ( PDF - 3.7 Mo )	102
	1-1.2.7 Capillary rise: Hirschwald coefficient, Apparent radius of capillary rise	113
	1-1.2.8 Overview on three-phase capillary equilibria	121

Chapter 1-2

Fluid Recovery and Modelling: Dynamic Properties

123

1-2.1	Intrinsic Permeability	123
	1-2.1.1 Definitions and Darcy's law	123
	1-2.1.2 Intrinsic permeability measurement principle	128
	1-2.1.3 Geometric parameters affecting permeability and simple models	138
	1-2.1.4 Porosity/Permeability relations in rocks ( PDF - 9.5 Mo )	144
	1-2.1.5 Effects of stress and temperature on the intrinsic permeability	163

1-2.2

Wettability of Reservoir Rocks (

PDF - 4.5 Mo

)

167

1-2.2.1 Definition and measurement of intermediate wettability

167

1-2.2.2 Wettability of reservoir rocks

173

1-2.3	Relative Permeability and End Points	179
	1-2.3.1 Overview	179
	1-2.3.2 Tentative simplification: search for the most important points on the relative permeability curve	184
	1-2.3.3 More information about the “End Points”, wettability effects	186
	1-2.3.4 Relative permeability measurement principle	191

Chapter 1-3

Log and Geophysical Analysis

199


1-3.1	Electrical Properties: Estimation of Hydrocarbon Saturation	199
	1-3.1.1 Resistivity of rocks saturated with electrolyte: Formation factor	199
	Figure 1-3.6 F vs. φ relation in two type of limestone ( PDF - 520 Ko )
	1-3.1.2 Resistivity of porous media saturated with a two-phase mixture	208
	1-3.1.3 The special case of clay media	213
	1-3.1.4 Effect of pressure and temperature on electrical properties	220

1-3.2	Seismic Properties: Effect of Porosity, Lithology and Nature of the Saturating Fluids on the Elastic Wave Velocity	221
	1-3.2.1 Simplified definitions: moduli, P and S waves, velocities, attenuations	222
	1-3.2.2 Scale effect: Ultrasonic, Sonic, Seismic frequency bands. Static properties, dynamic properties	227
	1-3.2.3 Laboratory velocity measurement principle and "path dispersion" problem ( PDF - 6.3 Mo )	230
	1-3.2.4 Effect of differential pressure on velocities: Hertz coefficient ( PDF - 3.1 Mo )	233
	1-3.2.5 Effect of the saturating fluid: Gassmann equation and its linear approximation as a function of Kfl	236
	1-3.2.6 Porosity/lithology/velocity empirical relations	239

1-3.3	Petrophysical Applications of Nuclear Magnetic Resonance	248
	1-3.3.1 Nuclear magnetic resonance (NMR), general principles	248
	1-3.3.2 Potential applications to petrophysics	254
	Figure 1-3.33 Comparison of amplitude spectra T2 (parameter V/A) and porosimetry access radius spectra in two limestones with double (Estaillades) or triple (Brauvilliers) porous networks ( PDF - 1 Mo )

PART 2
SCALE CHANGES AND CHARACTERISATION OF POROUS MEDIA: METHODS AND TECHNIQUES

Chapter 2-1

Measurement Representativeness and Reservoir Characterisation

265

2-1.1	Overview on the Effect of Damage, Stress and Temperature Variations on Petrophysical Characteristics	265
	2-1.1.1 Damage to laboratory samples	265
	2-1.1.2 Influence of stresses and temperature on petrophysical characteristics	266

2-1.2	Representative Elementary Volume, Homogeneity, Isotropy	272
	2-1.2.1 Definition of Representative Elementary Volume (REV)	272
	Figure 2-1.4 Water/air saturation map for the same slice of bioclastic limestone ( PDF - 3.6 Mo )
	2-1.2.2 Homogeneity and Isotropy	281
	2-1.2.3 Continuously variable REV: self similarity and fractal object	288

2-1.3	Scale Changes	293
	2-1.3.1 From plug to core and well logs ( PDF - 3.6 Mo )	294
	2-1.3.2 From core to well test (“bulk” and “matrix” property)	311
	Figure 2-1.21 Example of fracture swarm (or fracture corridor) affecting the Dogger limestone and dolomite bar at the Pas de l'Escalette (Hérault, France) ( PDF - 1.5 Mo )

2-1.4	Rock Typing	317
	2-1.4.1 Rock Typing, description and terminology difficulties
	2-1.4.2 Core Rock Typing	318
	2-1.4.3 Log Rock Typing	322

Chapter 2-2

Porous Network Observation Techniques

325

2-2.1	Thin Sections and Epoxy Pore Casts	325
	2-2.1.1 Impregnation of porous networks by resins	325
	2-2.1.2 Observation of thin sections under optical microscope	327
	2-2.1.3 Observation under Scanning Electron Microscope (SEM)	330
	Figure 2-2.6 Principle used to produce epoxy pore casts ( PDF - 2 Mo )

2-2.2	Visualisation of Fluid Location in Pores	333
	2-2.2.1 Direct observations of natural fluids: Cryo-scanning electron microscopy	334
	2-2.2.2 Indirect observations using polymerisable liquids or fusible metal	336

2-2.3	X-Ray Tomography	342
	Figure 2-2.15 Use of fusible metal (Wood's alloy type) to visualise the distribution of wetting and non-wetting phases ( PDF - 1.3 Mo )
	2-2.3.1 The medical scanner	344
	2-2.3.2 Microtomography devices	347

2-2.4	Mineralogical Analysis Applied to Petrophysics: X-Ray Diffraction and Fluorescence	349
	2-2.4.1 Some reminders about mineralogy/crystallography	350
	2-2.4.2 Laboratory techniques	351

References	357
Porosity Terms Glossary-Index	365
Subject Index	371
Author Index	381

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Ouvrages

A Geoscientist's Guide to Petrophysics