Application of geochemical parameters for
classification of crude oils from Egypt
into source-related types
M.Sh. El-Gayar
a,
*
, A.R. Mostafa
b
, A.E. Abdelfattah
c
,
A.O. Barakat
b
a
Department of Chemistry, Faculty of Science, Alexandria University, P.O. Box 426, 21321 Alexandria, Egypt
b
Department of Environmental Sciences, Faculty of Science, Alexandria University, Alexandria, Egypt
c
Amerya Petroleum Refining Company, Alexandria, Egypt
Received 30 October 2001; received in revised form 18 January 2002; accepted 12 March 2002
Abstract
Seven crude oils representing the different petroleum-bearing basins in the Western Desert were
characterized by a variety of biomarker and nonbiomarker parameters. For comparison, one crude oil
from the Gulf of Suez region has also been studied. The oils have been analyzed for geochemical
biomarkers using GC and GC-MS techniques. The results reveal significant differences within the
oils that suggest five oil types. Type 1 oils from the Gulf of Suez show C
29
/C
30
17a(H) hopane ratio
>1, high C
35
homohopane index, and the presence of considerable amounts of gammacerane
indicating a marine saline carbonate or evaporite source rock and highly reducing (low Eh)
conditions. Type 2 oils from Matruh basin and type 3 oils from Shushan basin are very similar and
show relatively high Pr/Ph ratios, low sulfur and metal contents, paucity of C
30
steranes and the
presence of high relative abundance of 17a(H) diahopane (C
30
*) suggesting that they probably
originated from source rocks containing a significant proportion of higher plant material. Another
related feature of these oils is the absence of 18a(H)-oleanane which suggests a source age older than
Cretaceous. Type 4 oils from Abu-Elgharadig basin show terpane distribution dominated by C
24
tricyclic, absence of C
30
*-diahopane and medium diasterane/sterane ratios which reflect generation
from marine siliciclastic source rocks. Type 5 oils from Alamein basin possess source biomarkers
indicating a mixed contribution of terrestrial and marine sources. The presence of measurable
amounts of oleanane in this type of oils suggests source rocks deposited in deltaic or near shore
environment in Post-Cretaceous basin. D 2002 Published by Elsevier Science B.V.
Keywords: Biomarkers; Oil types; GC and GC/MS; Egyptian crudes; Western Desert; Source rocks
0378-3820/02/$ - see front matter D 2002 Published by Elsevier Science B.V.
PII: S 0378-3820(02)00015-2
*
Corresponding author.
www.elsevier.com/locate/fuproc
Fuel Processing Technology 79 (2002) 13 – 28