New insights into the discovery and reservoir formation of the BZ19-2 large lithologic oilfield in the Bohai Sea
As exploration in the Bohai Sea area intensifies,discovering shallow and scale lithologic oil-gas fields has become increasingly challenging.In 2021,the BZ19-2 large fluverine lithologic oil-gas field was discovered in the central uplift of the southwest Bozhong Sag.This study analyzes the key reservoir formation conditions of the BZ19-2 Oilfield using seismic,thin section,and geochemical data.The results indicate that:①The formation of large-scale lithologic traps is controlled by frequent migration of large meandering rivers and cross-cutting superposition of sub-channels over different periods.②A vertically superimposed deep and shallow sink oil setting provides a favorable structural background for shallow oil and gas accumulation.③ The NW-trending channel sand body in the lower member of Minghuazhen Formation within the BZ19-2 structure formed a"first-order charging"with large hydrocarbon column height facilitated by an optimal"fault-ridge"configuration.④The BZ19-4 structure is adjacent to the oil-source fault to form a"double ridge inheritance-strong active fault-local sand body"reservoir formation model,whereas the BZ19-2 structure is far away from the oil-source fault to form a"double ridge relay-strong active fault-continuous sand body"reservoir formation model.The discovery of the BZ19-2 Oilfield confirms the exploration potential of shallow lithologic reservoirs in the mid-depression uplift area of the Bohai Sea,which is helpful to achieve new breakthroughs in large-scale lithologic exploration in similar regions.
Bohai SeaNeogeneBZ19-2BZ19-4lithologic oilfieldfluvial faciesreservoir formation model
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