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Slide 1Dr Elena Pasternak
Reservoir characterisationPETR3512
Rock properties. Overview
Slide 2Dr Elena Pasternak
Properties and characteristics of reservoirs & rocks
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Slide 3Dr Elena Pasternak
PROPERTIES OF ROCKS» INTRODUCTION» MINERALOGY AND GRAIN SIZE» WHOLE ROCK
– Porosity and permeability– Acoustic Properties– Electrical Properties– Radioactive Properties– Magnetic Properties– Mechanical Properties– Characterisation of Matrix Composition
» POROSITY, GRAIN SURFACES & PORE THROATS– Pore Geometry– Wettability– Capillary Pressure– Isopore Throat Concepts
Slide 4Dr Elena Pasternak
Mineralogy and grain size of reservoir and seal rocks
The most common minerals in reservoir rocks are quartz and calcite, while clays make up the major part of seals.
Trace minerals are often present as individual grains or as a cement.
Grain size is related to the properties of the minerals as well as the energy in the environment of deposition.
Grain size and sorting can vary considerably; however reservoir quality tends to reduce with reducing grain size. Accordingly, very fine grained rocks tend to have sealing properties.
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Slide 5Dr Elena Pasternak
Slide 6Dr Elena Pasternak
PROPERTIES OF ROCKS
Rock mainly composed of quartz with some feldspar (often altered) a few biotites and chlorites. Source : http://users.skynet.be/jm-derochette/sedimentary_rocks/
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Slide 7Dr Elena Pasternak
PROPERTIES OF ROCKS
Quartz crystals surrounded by micas in a clay cement?Source: http://users.skynet.be/jm-derochette/sedimentary_rocks/
Slide 8Dr Elena Pasternak
PROPERTIES OF ROCKS
Limestone containing skeletal material of small organisms.Source: http://www.glossary.oilfield.slb.com/
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Slide 9Dr Elena Pasternak
PROPERTIES OF ROCKS
Shale. The fine grains are clays with organic material. The larger grains are quartz.Source: http://www.glossary.oilfield.slb.com/
Slide 10Dr Elena Pasternak
Rock grain structure
Quartzite
Marble
(from B. Skinner, S.C. Porter, The dynamic Earth, 1995)
Conglomerate(from W.K. Hamblin, E.H. Christainsen, Earth’s dynamic systems, 1995)
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Slide 11Dr Elena Pasternak
Sandstones
Brahmaputra River
Source:
5umA B
C D
http://webmineral.com/data/ http://webmineral.com/data/
Examples of clay minerals in sandstones.
(A) Kaolinite, (B) Smectite, (C) Chlorite, (D) Illite
Slide 12Dr Elena Pasternak
More sandstones
Brahmaputra River
E F
USGS WebsiteUSGS Website
Examples of clay minerals in sandstones.(E) Kaolinite and Illite-smectite mixture (F) Glauconite (compacted grains).
Glauconite- Affects Log Readings Significantly– High Gamma-ray
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Slide 13Dr Elena Pasternak
Brahmaputra River
Source: USGS website and Haddad et al. Liverpool University
•Zone A is characterised by zoning.•Zone B is a zone of “zero solutions”(i.e., no indexing, which
makes it likely that this area is SiO2 but not quartz). •Zone C is characterised by small, euhedral quartz crystal
outgrowths.•Zone D is porosity, filled with epoxy resin
The Effects of Burial on Reservoir Rocks: Quartz overgrowths
Quartz
Slide 14Dr Elena Pasternak
Solid bodies and their behaviour under loading (examples)
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Slide 15Dr Elena Pasternak
Folding and
kinking at micro level
(from L. Dengler, 1976. Microcracks in crystalline rocks. In: Electron microscopy in mineralogy, 1992)
Slide 16Dr Elena Pasternak
Rock mass
folding
(from D. Powell, Interpretation of geological structures through maps, 1992)
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Slide 17Dr Elena Pasternak
Solid bodies and their behaviour under loading (examples)
Solid Earth
Rock mass folding
Courtesy ACcESS
Courtesy Hans Mühlhaus
Slide 18Dr Elena Pasternak
The microstructure of steel, showing large grains. This is a slice through one thread of a well-annealed nut. The nut came from a fireplace grate or andiron, so it was exposed to a lot of heat before being sliced in half and polished and prepared as a sample.
http://commons.wikimedia.org/wiki/Image:Microstructure_steel_annealed_nut.jpg
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Slide 19Dr Elena Pasternak
The microstructure of unaffected A36 steel: (a-left) white-ferrite, dark-pearlite and (b-right) pearlite region. Pearlite forms in bands due to manganese segregation and prior hot working.
http://www.tms.org/pubs/journals/JOM/0112/Biederman/Biederman-0112.html
Slide 20Dr Elena Pasternak
An EDX Analysis of eutectic region.
Eutectic formation (iron oxide-iron sulfide), etched 4% natal.
http://www.tms.org/pubs/journals/JOM/0112/Biederman/Biederman-0112.html
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Slide 21Dr Elena Pasternak
Oxidation and intergranularmelting; unetched
http://www.tms.org/pubs/journals/JOM/0112/Biederman/Biederman-0112.html
Severely eroded I beam cross sections, nominal composition (%) of A36 steel plate is: (0.29C max, 0.80–1.2Mn, 0.04P, 0.05S, 0.15–0.3Si bal Fe)
Slide 22Dr Elena Pasternak
Underlying structure
the microstructure of annealed brass as it is tensile tested.
http://www.matsci.ucdavis.edu/MatSciLT/materialsylvania/GalleryMatSci.htm
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Slide 23Dr Elena Pasternak
Luders lines (bands) in steelhttp://www.matsci.ucdavis.edu/MatSciLT/materialsylvania/GalleryMatSci.htm
Luders bands forming during the initial phases of a tensile test.
Slide 24Dr Elena Pasternak
Foam structures
Conventional open cell polymer foam. Scale mark: 2 mm.
http://silver.neep.wisc.edu/~lakes/sci87.html
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Slide 25Dr Elena Pasternak
SWNT tested
Single-walled carbon nanotubes imaged using a scanning electron microscope.
http://www.matsci.ucdavis.edu/MatSciLT/materialsylvania/GalleryMatSci.htm
Slide 26Dr Elena Pasternak
Why did we have ‘irrelevant’ microstructures here?
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Slide 27Dr Elena Pasternak
Microstructure affects the quality of reservoir!!!
Slide 28Dr Elena Pasternak
gzP
gzzP
ρ
ρ
=∂∂
=
=
Gradient Pressure
)(
Characteristics of reservoirs & rocks
pressure and temperature at depth» Pressure increases with depth
» Temperature increases with depth
PRESSURE (vertical):» the pressure on the fluid in the reservoir rock pores depends
on the overburden height and type:
2 extremes: If overburden is a column of water (totally supporting rock matrix)
Pressure gradient is 10MPa/km (hydrostatic pressure)overburden is a column of rock
Pressure gradient is 27MPa/km (geostatic pressure)
Overburden is a weight of what is ‘above’ you when you are underground
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Slide 29Dr Elena Pasternak
Characteristics of reservoirs & rocksPressure increases with depth
10 MPa/km(hydrostatic limit)
27 MPa/km(geostatic limit)
Slide 30Dr Elena Pasternak
Characteristics of reservoirs & rocksTemperature increases with depth
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Slide 31Dr Elena Pasternak
Characteristics of reservoirs & rocks
pressure and temperature at depth» Pressure increases with depth
» Temperature increases with depth
TEMPERATURE:» Average temperature gradient is 30°C/km
» Ranges from 20 °C/km to 80 °C/km, depending on local heat fluxes, and thermal conductivities of rocks
What’s the source of the heat?
Slide 32Dr Elena Pasternak
Characteristics of North West Shelf
Reservoir P ~ 35 MPa
Reservoir T ~ 110°C
Depth z ~ 3.5 km
⇒ Pressure gradient of 10MPa/km » ⇒hydrostatic regime
⇒Temperature gradient of ~ 25 °C/km» ⇒ normal hotness
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Slide 33Dr Elena Pasternak
Temperature gradients examples!
Slide 34Dr Elena Pasternak
Hot Dry Rock Reserves in the US
http://qvack.lanl.gov/HDR/barhdr.html
Clean geothermal energy
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Slide 35Dr Elena Pasternak
ConceptWorld HDR energy resource is 30 times of fossil energy resourceAccessible: < 10 kmSite determination» Location» Depth/temperature
Reservoir development» Porous rock » Hydraulic fracture
http://qvack.lanl.gov/HOTDRYROCK.HTML
Slide 36Dr Elena Pasternak
HDR in Australiahttp://www.petrol.unsw.edu.au/research/resource.html
Resource: 7,500 years of the current energy consumption in AustraliaOver 80 % of the resource is in the Eromanga Basin (in the north-eastern corner of South Australia and the south-western corner of Queensland
School of Petroleum EngineeringThe University of New South WalesSydney 2052 Australia
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Slide 37Dr Elena Pasternak
HDR Process
Queensland
http://www.nrw.qld.gov.au/factsheets/pdf/mines/m7.pdf
Slide 38Dr Elena Pasternak
Stresses are not hydrostatic!
Hydrostatic(a) if overburden is a column of water (vertical
pressure)(b) if they are the same in all directions (rock
mass is similar to a liquid)
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Slide 39Dr Elena Pasternak
Borehole breakouts 1
Dog earingDyskin (2007)
Slide 40Dr Elena Pasternak
Borehole breakouts 2
Maximum principal
stress
Breakout
depth
angle
Dyskin (2007)
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Slide 41Dr Elena Pasternak
Borehole breakouts
A. Dyskin
http://www.hydrofrac.com/hfb_home.html
3 m diameter drift at 420 m level in the Underground Research Laboratory (URL), Canada
8/7/2008 41
Slide 42Dr Elena PasternakA. Dyskin
Shapes of borehole breakouts
http://www.itascacg.com/petro_borehole.html
8/7/2008 42
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Slide 43Dr Elena PasternakA. Dyskin
Borehole breakouts 2
http://earthquakes.ou.edu/RaSim6_Hiroshi_Poster.pdf
8/7/2008 43
Slide 44Dr Elena PasternakA. Dyskin
Underground Research
Laboratoryhttp://inisjp.tokai.jaeri.go.jp/ACT95E/4/4-10.HTM
Whiteshell Laboratories, Eastern Manitoba, CanadaNuclear Fuel Waste Management Program, 1990-1993
8/7/2008 44
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Slide 45Dr Elena PasternakA. Dyskin
URL Experiment
8/7/2008 45
Slide 46Dr Elena PasternakA. Dyskin
Observed Fractures
(After Read and Martin, 1996)8/7/2008 46
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Slide 47Dr Elena Pasternak
Original (Virgin) Stress StateGravitational stressTectonic stressResidual stress
Factors influencing the stress state•Surface topography•Erosion•Non-Homogeneity•Discontinuities
•influence the stress state•serve as indicators of the existing stress state
•Time•Presence of other mines and excavations
Dyskin (2007)
Slide 48Dr Elena Pasternak
Gravitational Stress
Heim’s hypothesis
σv
σh=K σv
h
Terzaghi: Rock mass is modelled as an isotropic elastic body with lateral constrain (ν is Poisson’s ratio)
K K=−
≤ ≤νν1
0 1,
p ~ γhHydrostatic hypothesis(γ is the average rock unit weight)
σv , σh
Weight of overburden
Shear stresses are neglected
σv ~ γh
Dyskin (2007)
γ=ρg – self-weight
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Slide 49Dr Elena Pasternak
Australia Stress Map
http://www.asprg.adelaide.edu.au/asm/maps.html
Dyskin (2007)
Slide 50Dr Elena Pasternak
Dependence of depth
Brown and Windsor (1990)
Dyskin (2007)
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Slide 51Dr Elena Pasternak
Dependence of depth - 2
Brown and Windsor (1990)
Dyskin (2007)
Slide 52Dr Elena PasternakA. Dyskin
Injection Induced Earthquakes(after Hsieh and Bredehoeft et al., 1981)
8/7/2008 52
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Slide 53Dr Elena PasternakA. Dyskin
Petroleum Induced SeismicitySegall (1989)
8/7/2008 53
Slide 54Dr Elena PasternakA. Dyskin
Gazli Gas Field, UzbekistanShallow gas reservoir (≈2 km)No prior seismic historyThe strongest reported earthquake correlated to gas production (M = 7+)No noticeable subsidencePressure decline from 7 MPa in 1956 to 1.5 MPa in 1985Deep locations of induced earthquakes (≈ 10−15 km)
Simpson and Leith(1985)8/7/2008 54
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Slide 55Dr Elena Pasternak
Intact rock(no through-going fractures)
Rocks and Rock Masses
Direct measuring of fundamental propertiesIndex testing as a comparative measure of rock quality
Discontinuities(fractures)
Rock Mass
DislocationsMicrocracks (microfissures)Cracks (fissures)JointsBedding planesFaults
Important Factors•Rock structure•In situ stress•Fluid flow in the rock mass
Slide 56Dr Elena Pasternak
Rock PropertiesSpecific gravity γrock/ γwater = 2.1 - 7.6Porosity (0.1% - 40%)Permeability (low)Thermal properties (low thermal conductivity)FrictionStrength» Uniaxial (unconfined) compressive strength» Tensile strength» Parameters of strength (fracture) criteria for triaxal
compression» Point load index
Deformability» Static moduli» Dynamic moduli
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Slide 57Dr Elena Pasternak
Characteristics of reservoirs & rocks
types of rock» traps made up of porous rock (containing
hydrocarbon fluid) and sealed by non porous/impermeable shales.
» Porous rock:Sandstones (90% of reservoirs)Carbonates
» porosity & permeability are the key rock characteristics
» others are mechanical strength, degree of consolidation, distribution of particle & pore sizes, etc
Slide 58Dr Elena Pasternak
Mechanical properties of rocksKnowledge of the mechanical properties of rocks is important in formation evaluation, drilling, development planning and production.
These properties include the inelastic properties such as fracture pressure gradient and formation strength as well as the elastic properties such as Young’s modulus, shear modulus, Poisson’s ratio and bulk pore compressibility.
Estimation of these properties requires lithology, porosity, bulk density, together with compressional and shear wave slowness as log data input.
These properties are useful in borehole stability analysis, sandproduction prediction, hydraulic fracture design and optimization, compaction/subsidence studies drill bit selection, casing point selection and casing design and other applications