This paper is the result of oil and gas exploration engineering.
[Objective]The target layer for oil and gas exploration in the Niuyingzi depression in western Liaoning Province has been MesoNeoproterozoic. Due to tectonic uplift and other factors, the Jurassic Beipiao Formation, which is an important hydrocarbon exploration target widely exposed in other basins in western Liaoning, is not found on the surface of this depression.
[Methods]During the drilling of the LLD1 well, a set of thick dark mudstone layers were discovered beneath the Mesoproterozoic carbonates. Based on correlations of lithology and spore-pollen assemblages of the newly discovered mudstones with those from the Beipiao Formation in the Sanbaosikeng section of Beipiao Basin in western Liaoning Province.
[Results]The layers discovered were from the Beipiao Formation.
[Conclusions]Organic geochemical indexes indicate that the mudstone is of high organic matter abundance and high hydrocarbon generation potential. Hence, mudstones from Beipiao Formation in this area is a set of high-quality hydrocarbon source rock worthy of exploration. The discovery of thick dark organic-rich layers indicates that the Jurassic Beipiao Formation is a new target for oil and gas explorations in the Niuyingzi Depression. Moreover, this new discovery also provides important basic geological information for the study of tectonic evolution and hydrocarbon geological conditions in western Liaoning Province.
Highlights: The dark mudstone below the middle Proterozoic nappe in LLD1 well is identified as Beipiao Formation by means of sporo-pollen assemblage and lithologic assemblage; According to geochemical indexes, the strata are identified as high quality hydrocarbon source rocks.