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
Density and hardness values can be tested and are tabulated in AGI Lab3 and by mineral on
Mindat.org. 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
FORMULA
DENSITY/HARDNESS
GRAIN/CEMENT
WATER
ACID
BASE
OIL
QUARTZ
FELDSPAR
KAOLINITE
MONTMORILLONITE
CALCITE
DOLOMITE
GYPSUM
HALITE
LIMONITE
HEMATITE
PYRITE
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.
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Geoscience 240 – Lab 1: Review of Properties Relevant to Fluid/Rock Interactions
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Your inferences for fluid-rock interactions: (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 great deal of the environmental behaviour, strength and economic value of sediments and
sedimentary rocks is their fluid retention and interactions. 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
GRAIN
SIZE
SORTING
COMPOSITION
grains/cement
PORES
shape
POROSITY
volume %
PERMEABILITY
hi -------------low
SAND #1
SAND #2
SILT
SANDSTONE
COQUINA
LIMESTONE
#1
PEAT
VOLCANIC
TUFF
PYROCLASTIC
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). (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
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.
ROCK
OCCURENCE
COMPOSITION
REACTION
TO HCL
PORES
shape
PORES
volume%
PERMEABILITY
hi-------------low
GRANITE
BASALT
GNEISS
SCHIST
SHALE #1
SHALE #2
LIMESTONE
#2
GYPSUM
GOSSAN
COAL
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!)
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Geoscience 240 – Lab 1: Review of Properties Relevant to Fluid/Rock Interactions
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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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