Geoscience 240 – Lab 1: Review of Properties Relevant to Fluid/Rock Interactions
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LAB 1 – REVIEW OF PROPERTIES RELEVANT TO FLUID/ROCK
INTERACTIONS
OBJECTIVE
Review the properties of minerals, rocks which are relevant to fluid-rock interactions and to
examine rocks structures related to aquifers, aquitards or reservoirs and the geophysical detection
of sediments.
PROCEDURE
1. Review of minerals in common sedimentary rock types, their physical properties and
chemical composition. (ref: Lab 3 in AGI). In addition to the persistent “rock forming
minerals listed” e.g.: Quartz, Alkali Feldspar (Orthoclase), Muscovite, Magnetite, Calcite,
Gypsum, Clays and accessory minerals that are hard and chemically resistant persist in
sediment: corundum, diamond, apatite, zircon, tourmaline, epidote, hornblende, magnetite
2. Review of common sediments and porous sedimentary rocks (Aquifer/reservoir rocks).
These include: porous, uncemented or fractured: well sorted sandstone, reef limestones,
breccias and occasionally fragmental volcanics (ref: Lab 6 and 5 AGI).
3. Review common impermeable rock types as reservoir caps, basin floors and aquicludes.
(ref: Lab 6 plus parts of 5 and 7 in AGI) Impermeable rocks and aquacludes: shale, salt,
gypsum, tillite and tightly cemented conglomerate, sandstone or limestone as well as
igneous and metamorphic basement rocks, and intrusions which cut sediments such as sills
and dykes.
4. Porosity: the spaces in rocks: pores, cracks, vesicles, vugs, joints, faults and caverns; usually
filled with fluid especially below the water table.
5. Permeability: the interconnectedness of porosity. Often downhole geophysical logging
tools (density, resistivity, gamma ray, interval velocity, self potential, induction etc.) sense
differences in porosity and permeability from which we deduce lithology.
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Geoscience 240 – Lab 1: Review of Properties Relevant to Fluid/Rock Interactions
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PART 1: REVIEW AND EXAMINE VARIOUS MINERAL PROPERTIES
A. Density and hardness values can be tested and are tabulated in AGI Lab3 and by mineral on
Mindat.org. Check if this minerals commonly occurs as grains or as cements or both. Use sandpaper,
a streak plate, watch glass or petri dish and test a small amount of mineral powder with dH2O, 3N
HCl, NaOH and Oil and examine visually and by feel to note any particular interactions. Does it wet
readily? Does it react, turn colour, generate a gas, bubble etc.
MINERAL
QUARTZ
FELDSPAR
KAOLINITE
MONTMORILLONITE
CALCITE
DOLOMITE
GYPSUM
HALITE
LIMONITE
HEMATITE
PYRITE
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FORMULA
DENSITY/HARDNESS
GRAIN/CEMENT
WATER
ACID
BASE
OIL
Geoscience 240 – Lab 1: Review of Properties Relevant to Fluid/Rock Interactions
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B. We pump fluids out of the Earth (Oil, water, brine, gas) or spill fluids onto the Earth (water, brine,
oils, chemical solutions, effluent etc.). Write a paragraph to summarize your findings apropos the
derivation, abundance, placement and behaviour (weathering, abrasion, framework, pore filling) of
these minerals in sediments. Are the minerals grains or cements or both? How would these mineral
– fluid interaction properties affect the behaviour of fluids in sediments and rocks considering
absorption or chemical reactions. Discuss implications for reservoir effects, fluid motions, and
waste disposal. Your inferences for fluid-rock interactions: Which minerals wet the most readily
and which the least. Do all minerals respond the same to water and oil wetting? Are particulary
minerals more prone to react with acids or bases? Which ones and describe their behavior. (10
points)
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Geoscience 240 – Lab 1: Review of Properties Relevant to Fluid/Rock Interactions
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PART 2: ESTIMATIONS OF POROSITY AND PERMEABILITY
A. A great deal of the environmental behaviour, strength and economic value of sediments and
sedimentary rocks is their fluid retention and interactions. Composition of grains and cements and
their textures affect: porosity, wetting and permeability. Note the minerals which form the grains
and the cements by ecamining them under a hand lens or binocular scope. Sometimes we only
measure a rock’s porosity and do not identify the rock directly,E.g. porosity logs may sense fluids
not rock type. The best aquifers and reservoirs are unconsolidated sediments and porous
sedimentary rocks. Examine the sediment or sedimentary rock and describe its grain size, grain
composition (mineral or rock type) and describe and make an estimate of its porosity and
permeability. Test it against compressed air and water. Devise a method to measure its absolute
porosity and relative permeability. Devise a test for aquifer value, taking into account both water
delivery and quality.
SED/ROCK
SAND #1
SAND #2
SILT
SANDSTONE
COQUINA
LIMESTONE
#1
PEAT
VOLCANIC
TUFF
PYROCLASTIC
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GRAIN
SIZE
SORTING
COMPOSITION
grains/cement
PORES
shape
POROSITY
volume %
PERMEABILITY
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Geoscience 240 – Lab 1: Review of Properties Relevant to Fluid/Rock Interactions
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B. Fill out the descriptive table and summarize your results. Rank the sediments in the space below
in terms of which would be the best to worst aquifer and discuss why (porosity, permeability, water
quality). Water reservoirs are ranked by: size/abundance, mechanical quality of water (turbidity
suspended minerals such as clays, silt or organic matter(10 points)
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Geoscience 240 – Lab 1: Review of Properties Relevant to Fluid/Rock Interactions
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PART 3: EXAMINATION OF IGNEOUS AND METAMORPIC ROCKS FOR
AQUICLUDE AND AQUITARD PROPERTIES
C. Igneous and Metamorphic Rocks are sources for sediments but generally act as aquicludes and
aquitards (tight rocks). Examine the specimens and fill out the descriptive table. Composition
refers to minerals present. Occurrence denotes a geological environment such as plutons, mountain
belts, sedimentary basins etc.
ROCK
GRANITE
BASALT
GNEISS
SCHIST
SHALE #1
SHALE #2
LIMESTONE
#2
GYPSUM
GOSSAN
COAL
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OCCURENCE
COMPOSITION
REACTION
TO HCL
PORES
shape
PORES
volume%
PERMEABILITY
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Geoscience 240 – Lab 1: Review of Properties Relevant to Fluid/Rock Interactions
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B. Consider if this rock weathered, what sorts of mineral particles or other components would end
up in sediments. For example, Granite might weather to smaller lithic granite pebbles or rand
grains or grains of quartz, feldspar, micas etc. For each type describe the likely geological setting of
how each rock might occur as a confining layer to impede water motion (cap rock or basin floor).
(Don’t forget the principle of superposition!) Consider each of these rocks as a potential fractured
reservoir and comment on and rank their potential values as aquifers for water delivery and quality
(clarity, turbidity, chemistry, taste etc.) (10 points)
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Geoscience 240 – Lab 1: Review of Properties Relevant to Fluid/Rock Interactions
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PART 4: TESTING THE VOLUME AND % WEIGHT CAPICITY FOR WATER WITH
VARIOUS MATERIALS
Determine the volume and weight % of water that can fill a graduated cylinder containing:
a) uniform sized marbles
b) vermiculite and
c) poorly sorted coarse beach sand
d) Compare and contrast these 3 materials for the volumes of water they will hold and that can
be delivered (drained) from them. Don’t forget to account for the mass of the cylinder!
MATERIAL
Dry
Volume
(mL)
Dry Wt.
(grams)
Wet
Volume
(mL)
Wet Wt.
(grams)
Porosity %,
Wt%
H 2O
volume %
recovered
MARBLES
VERMICULLITE
BEACH SAND
e) Summarize and compare these results and discuss which would make the best aquifer in
terms of capacity, delivery and water quality. (6 points)
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