laboratory methods ofCleaning and Saturation(Rock Sample Preparation)

1. Reservoir Rock Laboratory Course (1st Ed.)

2. 1. Petrophysics
2. Coring and Plugging

3. 1. Without Distillation methods
2. Soxhlet Extraction method
3. Dean-Stark Distillation-Extraction
4. Conclusions and Recommendations

5. Cleaning and Saturation
Determination
Objectives:
Cleaning and drying the core samples
Introduction and Theory:
Before measuring porosity and permeability,
the core samples must be cleaned of residual fluids and
thoroughly dried.
The cleaning process may also be a part of fluid
saturation determination.
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6. Direct Injection & centrifugal methods
Direct Injection of Solvent
The solvent is injected into the sample in a continuous
process.
The sample is held in a rubber sleeve thus forcing the
flow to be uniaxial.
Centrifuge Flushing
A centrifuge which has been fitted with a special head
sprays warm solvent onto the sample.
The centrifugal force then moves the solvent through
the sample.
The used solvent can be collected and recycled.
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7. Gas Driven method
Gas Driven Solvent Extraction
The sample is placed in a pressurized atmosphere of
solvent containing dissolved gas.
The solvent fills the pores of sample.
When the pressure is decreased,
the gas comes out of solution,
expands,
and drives fluids out of the rock pore space.
This process can be repeated as many times as
necessary.
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9. Soxhlet extractor
A Soxhlet extractor is a piece of
laboratory apparatus invented
in 1879 by Franz von Soxhlet.
It was originally designed for
the extraction of a lipid from a
solid material.
Typically, a Soxhlet extraction is
only required where the
desired compound has a limited
solubility in a solvent, and the
impurity is insoluble in that
solvent.
Soxhlet mechanism
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10. Soxhlet Extraction Apparatus
A Soxhlet extraction apparatus
is the most common method
for cleaning sample, and is
routinely used by most
laboratories. As shown in the
Figure, samples to be cleaned
are placed in a porous thimble
inside the Soxhlet.
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11. Procedure
Electric or gas heaters are used
to vaporize the solvent.
The hot vapors meet the samples in the thimble and
dissolve the oil and water.
Vapors are condensed and cover the sample until over-
flown back to the solvent flask.
The extraction process continues for several hours
and is terminated
when no more oil remains in the samples.
This is recognized when the condensing vapors remain
clean because no oils is left in the cores to be dissolved.
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12. Remarks
After the extraction,
samples are dried in an electric oven.
Sometimes vacuum may also be applied to the oven.
A complete extraction may take several days to several
weeks in the case of low API gravity crude or presence
of heavy residual hydrocarbon deposit within the core.
Low permeability rock may also
require a long extraction time.
The dried samples are kept
in a desiccator sealed with grease and
has some moisture absorbents at its bottom.
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14. Dean-Stark apparatus
The Dean-Stark apparatus or
Dean-Stark receiver or distilling
trap or Dean-Stark Head is a
piece of laboratory glassware
used in synthetic chemistry to
collect water (or occasionally
other liquid) from a reactor.
It was invented by E. W. Dean
and D. D. Stark in 1920 for
determination of the water
content in petroleum.
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15. Dean-Stark distillation procedure
The Dean-Stark
distillation provides a
direct determination of
water content.
The oil and water area
extracted by dripping a
solvent, usually
toluene or
a mixture of acetone
and chloroform,
over the plug samples.
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16. Calculation of water and oil content
In this method,
the water and solvent are vaporized,
recondensed in a cooled tube in the top of the
apparatus and
the water is collected in a calibrated chamber.
The solvent overflows and
drips back over the samples.
The oil removed from the samples
remains in solution in the solvent.
Oil content is calculated by
the difference between the weight of water recovered
and the total weight loss after extraction and drying.
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18. direct-injection, centrifugal and gas
driven-extraction methods
The direct-injection method is effective, but slow.
The method of flushing by using centrifuge is
limited to plug-sized samples.
The samples also must have sufficient mechanical
strength to withstand the stress imposed by centrifuging.
However, the procedure is fast.
The gas driven-extraction method is slow.
The disadvantage here is that it is not suitable for poorly
consolidated samples or chalky limestones.
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19. Distillation methods
The distillation in a Soxhlet apparatus is slow, but is
gentle on the samples.
The procedure is simple and very accurate water content
determination can be made.
Vacuum distillation is often used for full diameter
cores because the process is relatively rapid.
It is also frequently used for poorly consolidated cores
since the process does not damage the sample.
The oil and water values are measured directly and
dependently of each other.
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20. solvents
In each of these methods,
the number of cycles or
amount of solvent which must
be used depends on
the nature of
the hydrocarbons being
removed and
the solvent used.
Often, more than one
solvent must be used to
clean a sample.
The solvents selected must
not react with the minerals
in the core.
The commonly used solvents
are:
Acetone
Benzene
Benzen-methol Alcohol
Carbon-tetrachloride
Chloroform
Methylene Dichloride
Mexane
Naphtha
Tetra Chloroethylene
Toluene
Trichloro Ethylene
Xylene
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21. 1. (KSU) M. Kinawy. “Reservoir engineering
laboratory manual" Petroleum and Natural
Gas Engineering Department, King Saud
University, Riyadh (2009).
2. “Soxhlet Extractor.” Wikipedia, the free
encyclopedia 5 July 2014. Wikipedia. Web. 22
July 2014.
3. “Dean-Stark Apparatus.” Wikipedia, the free
encyclopedia 5 July 2014. Wikipedia. Web. 22
July 2014.