Oil Accumulation Model and Its Main Controlling Factors in Lower Yanchang Formation, Wuqi-Dingbianarea, Ordos Basin, China

Table 1

Organic geochemical parameters of C7 members in study area.

Layer

“A” (%)

Max peak temperature; Tmax (°C)

Total organic carbon; TOC (%)

Potential hydrocarbon generation amount; (mg/g)

Saturated hydrocarbons (%)

Aromatic (%)

Conversion rate of asphalt “A” (%)

Ro (%)

OEP

Rage

Average

Rage

Average

Rage

Average

Chang7

0.1 ~ 1.0

450~470

2.45~5.28

2.51~7.10

14.2 ~ 65.5

19.57~21.8

3.60~41.59

12.86

0.85~1.18

1.07

0.99~1.09

1.02

Hydrocarbon (saturated and aromatic) amount of asphalt “A” of the source rocks in C7 is between 45% and 70%, while the ratio of saturated and aromatic hydrocarbon is between 0.72 and 3.7 (Table 1), meaning that the kerogen of C7 in Wuding area is mainly type II₂ (sapropelic-humic type), which is good hydrocarbon source rock.