Petrophysics presentation

1. Petro Physics presentation
Group member:15PG143,15PG149,15PG146,15PG42,15PG29

2. Object:
 To find the fluid saturation in given
core sample using modified ASTM
saturation method

3. Introduction
 A hydrocarbon solvent that is insoluble in water is used to leach the fluids from a
saturated rock. A special graduated receiving tube may be used to collect the extracted
water, thus providing a direct measurement of the water saturation
 Once the water saturation is known, the oil saturation may be calculated from indirect
gravimetric measurement of the rock. The gas saturation is then obtained indirectly by
difference because:
 Sg + Sw + So = 1.0
 After extraction of the fluids and drying, the cleaned core may be used for measurement
of other petrophysical properties and quantities (permeability, porosity, sieve analysis,
mineral grain density, etc)

4.  The boiling point of the hydrocarbon fluid used for the extraction must be higher than
the boiling point of water and preferably lower than the boiling point of the
hydrocarbons in the core (toluene is the most frequently used solvent: BP = 110.6"C).
When the boiling point of the solvent is higher than 212°F (lOO°C), water vaporizes
from the core and travels upward within the rising solvent vapors. The vapors (solvent
plus water) are condensed and collected in a side receiver where the water is trapped at
the bottom of the tube because its density is higher than the density of the solvent. The
excess solvent drains back into the boiling pot where it is reheated to continue the
process of extraction.
 The crude oil that was originally a part of the core fluids will dissolve in the solvent. If
the boiling point of the crude oil is higher than the boiling point of the solvent, the
crude oil will remain in the boiling pot.

5. EQUIPMENT AND PROCEDURES
 1. Pour toluene into the boiling flask until the flask is three-fourths full of toluene (or
whatever hydrocarbon solvent is being used).
 2. Obtain the mass of the saturated core sample.
 3. Determine the bulk volume of the saturated core using a pycnometer.
 4. Assemble the extraction equipment, which will consist of a heating mantle, boiling
pot, extraction/collection tube, and a condenser.
 5. Determine the density of the crude oil.
 6. Set the heater control at a point where no gas or liquid can be seen escaping from the
top of the condenser during condensation.

6.  7. Record the volume of water collected in the graduated tube every 30 minutes. When
no more water is collected after two readings, turn off the heater and record the volume
of water collected.
 8. When the solvent cools, remove the core and dry it in an oven equipped with an
exhaust vent connected to a hood. If this type of oven is not available, allow the solvent
to evaporate from the core by placing it in a hood overnight, and then dry the core in an
oven.
 9. Obtain the mass of the dried core.
 10. Calculate the fluid saturation of the core from the data collected.

7. Sample Calculation
 Data:
Porosity = 0.20
Bulk volume = 25.0 ml
Density of the oil = 0.88g/ml
Mass of saturated core = 57.0g
Mass of dried core = 53.0g
Volume of water collected = 1.4 ml

8. Solution
 Calculate the pore volume
Pore volume = Porosity x Bulb volume
= 0.20 x 25.0 = 5.0ml
 Calculate the water saturation Sw
Water saturation, Sw, = Water volume/Pore volume = 1.4/5.0
= 0.28 = 28%

9.  Calculate the oil saturation So
Oil saturation, So = Oil volume/Pore volume
Now, Mass of oil = 57.0- 53.0- 1.4
=2.6g
Oil volume = Mass of oil/Density of oil
= 2.6/0.88
=2.95
hence, Oil saturation, So = Oil volume/Pore volume
= 2.95/5.0
= 0.59 = 50%
 Calculate the gas saturation Sg
Gas saturation, Sg, = 1.0 - So - S, = 1.8 - 8.28 - 0.59 = 0.13 = 13%

10. Advantages
 Accurate determination of water saturation
 Non-destructive to core sample
 Determination of water saturation by solvent extraction can be made part of the core
sample cleaning process for small incremental cost.

11. Disadvantage
 Slow (can take several days).
 Oil volume not directly measured.
 Oil remains in solvent.