Introduction

Petroleum (or crude oil) is a complex, naturally occurring liquid mixture containing mostly hydrocarbons, but containing also some compounds of oxygen, nitrogen and sulfur. It is often referred to as the “black gold”. Hydrocarbons are usually the primary component of crude oil, their composition can vary from 50%-97% depending on the type of crude oil and how it is extracted. Organic compounds like nitrogen, oxygen, and sulphur typically make-up between 6%-10% of crude oil while metals such as copper, nickel, vanadium and iron account for less than 1% of the total composition.

i) Formation of Crude Oil

Crude oil forms by the breaking down of large molecules of fats, oils and waxes that contributed to the formation of kerogen. This process began millions of years ago, when small marine organisms abounded in the seas. As marine life died, it settled at the sea bottom and became buried in layers of clay, silt and sand. The gradual decay by the effect of heat and pressure resulted in the formation of hundreds of compounds. Because petroleum is a fluid, it is able to migrate through the earth as it forms. To form large, economically recoverable amounts of oil underground, two things are needed: an oil pool and an oil trap. An oil pool, which is the underground reservoir of oil, may literally be a pool or it could be droplets of oil collected in a highly porous rock such as sandstone. An oil trap is a non-porous rock formation that holds the oil pool in place. Obviously, in order to stay in the ground, the fluids must be trapped, so that they cannot flow to the surface of the earth. The hydrocarbons accumulate in reservoir rock, the porous sandstone or limestone. The reservoir rock must have a covering of an impervious rock that will not allow the passage of the hydrocarbon fluids to the surface.

ii) Crude Oil Processing

The preparation of petroleum before it is sold to the consumers is very extensive. A large number of different products is obtained from the petroleum refinery. Most of them are used as fuels. A small but very important fraction is used as the basis for

the chemical industry which gives us such various such products as plastics, pharmaceuticals and textiles.

As usual, the oil well exploration is done mostly by geologist and engineering. The geologist function is to find new area of hyrocarbons potential to be explored. Then there are two types of engineer in charge, which is the drilling engineer and well engineer. After the oil has been pumped out, it will be transported to refinery stations.

For the refining process the very first step involves application of heat to evaporate components in the raw crude oil. The heated components are later separated based on its boiling point. In oil refining, the product generated from separation process is not fully customizable to suit market demand. A conversion process in oil refining process provides flexibility in generating more valuable product. While separation and conversion steps in oil refining process generate different chemical from the crude oil. Purification process helps oil refining process people to come out with product with lower sulfur content. This means a cleaner product will be generated in the oil refining process.

Then it will be stored in bulk terminal supply. From there, it will be transported to the consumer for daily usage of car fuel, jet fuel, construction, various cosmetics product and paved road constructions.

Objectives

1) To find the specific gravity value for the crude oil sample provided.2) To know the volume percentage of crude oil based on types of products

according to their distinctive boiling points.3) To determine the physical properties of various crude oil fractions.4) To gain knowledge on the flow of crude oil distillation processes.

Methods

i) First Distillation

Apparatus : Bunsen burner, funnel, retort stand, distillation flask, measuring cylinder and thermometer (400oC).

Material : 250ml of crude oil

Method :

1) Two 100ml and one 500ml of empty measuring cylinder was weighed. Repeat the steps for the distillation flask along with the cork.

2) 250ml of crude oil was inserted into the distillation flask with a long funnel (avoid from splashing onto the flask’s wall).

3) The weight was measured.4) The set up shown below ( Figure 1)5) The distillation was started. The movements of the mercury inside the

thermometer were observed and the first drop temperature was taken.6) The distillation continued and the temperature was controlled carefully to get

the product at range of 3-4ml/minutes. The volume of the product were measured for every 5oC rise in temperature.

7) The first cylinder was replaced by the second cylinder after the temperature reached 200oC.

8) The distillation process was continued and stopped at 275oC.9) The remaining of the crude oil in the flask was weighed and compared with

the weight before distillation. The difference was represented in percentage.10) The readings were recorded and a temperature-volume graph was

produced.11) The products and remains of distillation were kept in the dark room for

the next experiment.

Figure 1 Apparatus set up

ii) Second Distillation

Apparatus: The same apparatus as used in first distillation.

Materials: Remains of crude oil from first distillation

Methods:

1) The methods of first distillation were repeated.2) The first drop product’s temperature was taken and the readings of

measuring cylinder for every 5oC temperature raise were recorded with drop range of 2ml/minutes.

3) The distillation was stopped after the temperature reached 375oC.4) The density of product was determined.5) The percentage of the followings were calculated in accordance to the

original weight:a) Distillatesb) Remains

6) A graph of temperature against volume percentage was plotted.

Results

i) Before Distillation

M1 (distillation flask + thermometer + cork + base): 310.21g

M2 (distillation flask + thermometer + cork + base + crude oil): 515.80

Cylinder A: 144.20g

Cylinder B: 116.42

ii) First Distillation

Cylinder A:

a) Volumes recorded for every 5oC raised of temperature

Temperature (˚C )

Volume (ml)

90 0 (1st drop)95 0.1100 0.2105 0.4110 0.7115 1.3120 1.4125 1.7195 2.0200 4.0

b) Weight after distillation: 149.14g

Cylinder B:

a) Volumes recorded for every 5oC raised of temperature

Temperature (˚C )

Volume (ml)

200 0 (1st drop)205 0.3210 0.6215 0.7220 0.8225 0.9230 10235 14240 15245 19250 25255 33260 40265 55270 70275 80

b) Weight after distillation: 184.43g

iii) Second Distillation

After first distillation: Distillation flask + crude oil + thermometer + cork + base: 441.49g

After second distillation: Distillation flask + crude oil + thermometer + cork + base: 333.06g

Cylinder C (Before distillation): 215.79g

Cylinder C (After distillation): 322.58g

Cylinder C

Volumes recorded for every 5oC raised of temperature:

Suhu Volume (ml)110 0115 2120 2.5125 3.0130 3.5135 4.0140 4.5145 4.5150 5.0155 5.5160 6.0165 6.5170 7.0175 7.5

180 8.0185 10.00280 16.00285 23.00290 35.00295 37.00300 39.00305 43.00310 47.00315 51.00320 60.00325 70.00330 72.00335 82.00340 99.00345 103.00350 108.00355 111.00360 114.00365 119.00

Calculation

i. First Distillation

Weight Apparatus

Before Distillation

After Distillation

Cylinder A a = 114.20g e = 149.14gCylinder B b = 116.42g f = 184.43g

Distillation flask+Cork+Base+Thermometer c = 310.21g -Distillation

flask+Cork+Base+Thermometer+Crude Oild = 515.80g g = 441.49g

1. Initial weight of crude oil

= d - c

= 515.80g – 310.21g

= 205.59g

2. Final weight of crude oil

= g - c

= 441.49g – 310.21g

=131.28g

3. Weight of distillates in measuring cylinder A

= e – a

= 149.14g – 114.20g

= 4.94g

4. Weight of distillates in measuring cylinder B

= f – b

= 184.43g – 116.42g

=68.01g

5. Total distillates

= 4.94g + 68.01g

= 72.95g

6. Percentage of distillates over the initial weight of crude oil

Percentage of cylinder A = A / CO1 x 100% = 4.94g/205.59 x 100%

= 2.403%

Percentage of cylinder B = B /CO1x 100%

= 68.01/205/59 x 100%

= 33.0804%

ii. Second Distillation

WeightApparatus

Before distillation After distillation

Cylinder C a = 215.79g c = 322.58gDistillation

flask+cork+thermometer+base+crude oil(1st distillation)

b = 333.06g d = 310.21g

1. Remaining crude oil’s weight

= b – a

= 333.06g – 310.21g

= 22.85g

2. Weight of distillates in cylinder C

= b – a

= 322.58g – 215.79g

= 106.79g

3. Percentage of cylinder C = C/CO1 x 100%

= 106.79/205.59 x100%

= 51.943%

4. Percentage of remaining crude oil

= 22.85g/205.59 x 100%

= 11.114%

iii. Specific Gravity of Crude Oil

Weight of picnometer: 35.14g

Weight of picnometer + distilled water: 88.58g

Weight of picnometer + crude oil: 81.42g

Weight of distilled water: 88.58g – 35.14 = 53.44g

Weight of crude oil: 81.42 – 35.14 = 46.28g

Thus SG of oil = 46.28/53.44 = 0.8660

iv. API of crude oil

API = [ 141.5/Specific Gravity ] – 131.5g

= [ 141.5/0.8660 ] – 131.5g

= 31.895

v. Density of each distillates

Density = Mass/ Volume

1) A = 4.94g/4ml

= 1.24g/ml

2) B = 68.01g/80.0ml = 0.85g/ml

3) C = 106.79g/119ml = 0.90g/ml

Data Representation

i. Volume of distillates in cylinder A, B and C

Tempera

ture (˚C

)100

115195

205220

235250

265280

295310

325340

3550.0

20.0

40.0

60.0

80.0

100.0

120.0

140.0

Volume A (ml)Volume B (ml)Volume C (ml)

Figure 2 Volume - Temperature for Each Cylinder

ii. Cumulative Volume of Distillates in Cylinder A, B and C

Tempera

ture (˚C

)100

115195

205220

235250

265280

295310

325340

3550

400

800

1200

1600

Cumulative Volume (ml)

Volume (ml)

Figure 3 Cumulative Volume

Discussion

i. Characteristics of Crude Oila. Colour

Generally, petroleum is dark colour depend on the hydrocarbon content and also contamination percentage.

Colour Types of Crude OilLight colour Light paraffin

Black Rich of resin and asphaltVery Dark Colour High density

Brownish Low densityDark colour Umdergone oxidation process

b. Boiling Point

Boiling and burning point of crude oil depends on the degree of API. The higher the degree of API, the lower the boiling point and vice versa. Burning point is the ability of petroleum to burn because of the sparks of fire. The higher the degree of API the easier for it to burn because of sparks of fire. The American Petroleum Institute gravity, or API gravity, is a measure of how heavy or light petroleum liquid is compared to water. Crude oil that does not flow, or cannot be pumped without being heated or diluted is called bitumen, and generally has an API gravity of less than 10°.

American Petroleum Index ( API ) Type of Crude<10o Heavy

20o – 30o Medium

>30o Light

Since the degree of API calculated for the sample of crude oil provided is 31.895, thus in can be concluded that it is from light type of crude oil.

c. Smell

The smell of crude oil depends on chemical content and can be differentiated between sweet or sour. Paraffin and naphtene – rich crude oil gives a sweet smell while benzene and aromatics gives sour smell. Smell can be used to identify quality of crude oil. For this sample, it gives pretty sweet smell.

d. Specific Gravity

Specific gravity is one of the crucial things in determining in classifying crude oil. It value used to find the API. API is functional to know the quality of crude oil. The higher the specific gravity the lower the API degree and the quality are lower. Commonly, the specific gravity of crude oil is less than 1.0. The specific gravity for this sample of crude oil is 0.8860 which is for light oil.

e. Viscosity

Viscosity is the resistant force of fluid when an object move through it by sentipois. The light type crude oil has low viscosity. The higher the API degree, the lower the viscosity. For this sample, the viscosity is low since the API is pretty high.

Criteria of Crude Oil Characteristics of Crude OilColour Dark brown

Specific Gravity 0.8860 ( Light)Boiling Point Low boiling point

Viscosity LowSmell Sweet

ii. Characteristics of Distillates

Hunt(1979) Diagram

Based on Hunt diagram, it can be concluded that chemical composition of each distillates A, B and C are;

Measuring Cylinder Chemical ContentA N – ParaffinB Iso – ParaffinC Naphtene

Thus, based on the chemical composition, Hunt Diagram and eye observation, the physical properties are;

Physical Properties A B CColour Light colur Brownish Dark brown-BlackSmell Sweet Pretty Sweet SourViscosity Low Medium HighType of distillate Gasoline Kerosene Diesel + Light Oil

DistillateBoiling Point (oC) 0 – 200 200 – 250 250 – 400

Conclusion

The specific gravity for the crude oil is 0.8896 and the API degree is 31.895 that both indicate low viscosity, low boiling point, sweet smell. Thus it is a light grade oil.

For the distillates in cylinder A, it is made up of gasoline and chemical composition of n – paraffin. For cylinder B, the distillates is Kerosene and the chemical content of iso – paraffin. Lastly for measuring cylinder C, it is made up of diesel with mixture of light oil distillate with chemical content of Naphtene.

References

i. Sanudin Hj. Tahir, 2003. Geologi Petroleum. University Malaysia Sabah. Page 43-71.

ii. J.-P. Wauquier, 1994. Petroleum Refining: Crude Oil, Petroleum Products, Process Flowsheets, Volume 1. Page 1-26. (Google book)

iii. Laudon, E.C. 1995. Principles of Petroleum Geology. Simon and Schuster Trade

UNIVERSITI MALAYSIA SABAH

FACULTY OF SCIENCE AND NATURAL RESOURCES

SEMESTER 1 2014/2015

PROGRAM GEOLOGI

PETROLEUM GEOLOGY (SG30203)

TITLE : CRUDE OIL FRACTIONAL DISTILLATION

Lecturer’s Name Prof. Dr. Sanudin Hj. TahirDemonstrator’s Name Mr. Muhd. Nur Ismail B. Abdul Rahman

Students Name Sufrizan Bin DawingMatric No. BS12110630