Other Assessment Methods—An Overview
159
The geological age of each source and reservoir bed is known.
2.
The types of organic matter contained in each source bed are
3.
recognized.
The paleotectonic history of the stratigraphic column or paleo4.
heat fl ow of each source bed can be interpreted.
The thickness and lithology of each source bed can be esti5.
mated.
If the information relevant to the previous fi ve conditions is available, a burial and thermal modeling process can proceed as follows:
Unpack the entire stratigraphic column into the thickness at
1.
the time of deposition.
Reconstruct the deposition and compaction of the strati2.
graphic column with consideration to erosional surfaces.
Record the thermal history of each source bed during the com3.
paction process according to the principle of thermal dynamics given by the following equation:
1
1
dC K C
dt
= ×
(7.2)
where C 1 is the total amount of organic matter transformed into oil or
gas, t is the time, and K is a coeffi cient defi ned as follows:
K = A × e
−E∕RT
The law of Arrhenius is a special case of the Boltzmann equation:
dC 1 = A × e
−E∕RT
× C 1 × dt
(7.3)
where E is the molar activation energy (per mole) of the decomposition
of certain types of organic matter into oil; A is a factor controlled by the
decomposition condition, such as nature of the environment; C 1 is the
amount of organic matter at time t; T is the absolute temperature; and
R is the ideal gas constant.
The reconstruction process reveals (1) the geological time and depth
of each source bed entering into and leaving the oil and gas windows,
and (2) the current oil and gas windows.
Figure 7.3 shows an example from one of the basins situated in eastern China. The source bed is about 33.6 million years old, started to
generate oil 26 million years ago, and entered the oil window 18.5 million
159
The geological age of each source and reservoir bed is known.
2.
The types of organic matter contained in each source bed are
3.
recognized.
The paleotectonic history of the stratigraphic column or paleo4.
heat fl ow of each source bed can be interpreted.
The thickness and lithology of each source bed can be esti5.
mated.
If the information relevant to the previous fi ve conditions is available, a burial and thermal modeling process can proceed as follows:
Unpack the entire stratigraphic column into the thickness at
1.
the time of deposition.
Reconstruct the deposition and compaction of the strati2.
graphic column with consideration to erosional surfaces.
Record the thermal history of each source bed during the com3.
paction process according to the principle of thermal dynamics given by the following equation:
1
1
dC K C
dt
= ×
(7.2)
where C 1 is the total amount of organic matter transformed into oil or
gas, t is the time, and K is a coeffi cient defi ned as follows:
K = A × e
−E∕RT
The law of Arrhenius is a special case of the Boltzmann equation:
dC 1 = A × e
−E∕RT
× C 1 × dt
(7.3)
where E is the molar activation energy (per mole) of the decomposition
of certain types of organic matter into oil; A is a factor controlled by the
decomposition condition, such as nature of the environment; C 1 is the
amount of organic matter at time t; T is the absolute temperature; and
R is the ideal gas constant.
The reconstruction process reveals (1) the geological time and depth
of each source bed entering into and leaving the oil and gas windows,
and (2) the current oil and gas windows.
Figure 7.3 shows an example from one of the basins situated in eastern China. The source bed is about 33.6 million years old, started to
generate oil 26 million years ago, and entered the oil window 18.5 million