Download Introduction to ore-forming processes by Laurence

Introduction to ore-forming processes
by Laurence Robb. Blackwell Publishing
Sedimentary ore-forming processes (partial)
5.4 FOSSIL FUELS - OIL/GAS FORMATION
AND COALIFICATION
Figure 5.26 Simplified scheme illustrating the formation of oil, gas,
and coal by the progressive burial of different types of mainly
vegetative matter (after Hunt, 1979).
C
H
O
N
S
Carbohydrates
44
6
50
-
-
Lignin
63
5
31.6
0.3
0.1
Proteins
53
7
22
17
1
Lipids
76
12
12
-
-
Petroleum
85
13
0.5
0.5
-
Coal
70
5
23
1
1
Source: after Hunt (1979).
Table 5.1 Average chemical compositions (in wt %) of the main organic
building blocks compared to those of petroleum and a typical coal
Figure 5.27 Summary of the
stages and processes involved in
the transformation of organic
matter during burial to form oil
and gas (after Hunt, 1979)
Figure 5.28 Graph showing the relationships between temperature and time with
respect to the generation of oil and gas in sedimentary basins. The shaded area
refers to the optimum range of conditions for petroleum generation and the points
are actual examples of petroleum-bearing basins from several locations around the
world (after Connan, 1974).
Figure 5.29 Classification scheme
for kerogen types based on the
hydrogen index and oxygen index
(after Cornford, 1998). Inset diagram
shows the original classification of
kerogen on the basis of H/C and
O/C atomic ratios (after Tissot and
Welte, 1984).
Figure A Location and distribution of some of the major
oil and gas fields in the Arabian Gulf (after Shannon
and Naylor, 1989).
Figure 2 Interpretations of the evolving sedimentary environment
in the region of the Arabian Gulf during (a) mid-Jurassic and (b)
mid-Cretaceous times (after Shannon and Naylor, 1989).
Figure 5.38 (a) Phase diagram illustrating the
regions of gas hydrate stability under most
natural conditions in the near-surface (after
Kvenvolden and McMenamin, 1980). (b) Profile
across a typical ocean-sediment interface in a
continental margin setting, showing the
progressive increase in the width of the gas
hydrate stability zone in the ocean sediment with
increasing depth of sea water (after Kvenvolden,
1988).