Lacustrine turbidite channels and fans in the Mesozoic Songliao Basin, China

ABSTRACT The Songliao Basin is a large Mesozoic nonmarine petroliferous basin in northeastern China. Based on an analysis of high‐resolution three‐dimensional seismic data, a large‐scale lacustrine turbidite channel and fan system is identified within the lacustrine mudstone of the Nenjiang Formation in the central depression. The system was fed by a delta complex and extends to the south along the Daqing anticline. This system is composed of three trunk channels and four tributary channels, with a maximum length of about 71 km. Changes in channel patterns, specifically bifurcations and terminations into fans, are associated with gradient changes along the palaeoslope, which vary from 0.13 to 0.02°. Interpretation of geophysical well logs and core indicate that channel sand bodies are oil charged. The widest channel sandstone body is about 600 m with an average around 300 m, and the maximum thickness of sandstone is more than 6 m with an average of about 3 m. The sandstone bodies of the turbidite system, which are encased within organic‐rich source rocks, provide a new target for hydrocarbon exploration and development.