Study On Geochemical Field And Geochemical Exploration Discrimination Pattern

The key geocheraical prospecting indicators of 15 main hydrocarbon-bearing basins and their various characteristics have been analyzed statistically , and the genesis variation of the indicators have been discussd .Based on these results ,a criterion has been proposed to classify the regional geochemical field of these main hydrocarbon-bearing basins. Studies on the variation trend of the regional background field reveal that the geochemical background values decrease gradually from west to east, while the variation degrees increase constantly.Studies on the abundance of C1 , C2+ and ΔC in the western region in Sichuan basin suggest that the background field increases from south to north, while Hg abundance has the higher to lower distribution trend from west to east. In a word, the geochemical data distribute with variation regularity from the north to the south, which is characterized by the relative data cluster.Studies on the alkane and aromatic hydrocarbons in the drilling wells show that the two hydrocarbon series both have significant migration trends and variation regularities from the depth to the surface, indicating the fact that hydrocarbon vertical migration exists objectively. Thus, the near-surface hydrocarbon anomalies have their sources like "active water" , which verifies that the near-surface anomalies and the prediction results achived from these anomalies are reliable in Sichuan Basin.A geochemical exploration discrimination pattern over a shallow (Pentlaizhen Formation) and middle depth (Shaximiao Formation) gasfield has...