Energy Geoscience (Jan 2024)
Origin of condensate oil and natural gas in Bozhong 19-6 gas field, Bohai Bay Basin
Abstract
The discovery of the Bozhong 19-6 gas field has opened a new frontier for deep gas exploration in the Bohai Bay Basin, with a great potential for further gas exploration. However, poor understanding of oil and gas origin has been limiting the exploration progress in this area. To clarify the origin of condensate oil and gas in Bozhong 19-6 gas field, this study adequately utilized the organic geochemical analysis data to investigate the composition and geochemical characteristics of condensate oil and natural gas, and analyzed the relationship between condensate oil and the three sets of source rocks in the nearby sub-sags. Results show that the lighter components dominate the condensate oil, with a forward type predominance. The parent material of crude oil was primarily deposited in a shallow, clay-rich, low-salinity, weakly reducing aquatic environment. The condensate and natural gas have similar parent source characteristics and maturity, with Ro ranging from 1.4% to 1.6%. Both are products of high maturity stage, indicating that they are hydrocarbon compounds produced by the same group of source rocks in the same stage. Oil-sources correlation shows that condensate oil and gas mainly originate from the source rocks of the third member of Shahejie Formation in the nearby subsags of the Bozhong 19-6 structural belt.
