Sublaucustrine landslides and implications for hydrocarbon exploration

Submarine landslides or slope failures, formed by downslope gravity-driven movement of submarine sediments, are widely described and discussed in the literatures. Slope break of lacustrine basin is different from continent... [ view full abstract ]

Submarine landslides or slope failures, formed by downslope gravity-driven movement of submarine sediments, are widely described and discussed in the literatures. Slope break of lacustrine basin is different from continent slope in term of framework, sandbodies, scale, gradient and shape, but slope break is an ideal discharge place for gravity depositions. In recent years gravity deposition has become one of the major targets for reserve growth in China nonmarine basins. However, little attention has been paid to sublaucustrine landslides.
Here, I present some highlights of more than 10 years of my research studying subaquatic landslides. The study areas range from (1) the Songliao Basin, which is the largest(2×104km2) depression lacustrine basin in northeastern China; and (2) the Jiuquan Basin, which is a small scale(250km2) half-graben basin in northwestern China. Based on core, logging, 3D seismic and analysis data of these terrestrial basins, seismic responses, sedimentary characteristics and implication for hydrocarbon exploration of sublacustrine landslides have been studied.
Sublacustrine landslides are widely developed in Chinese continental basins. The single area ranges from 4 to 300 km2, and the maximum thickness can reach up to 150m. The sublacustrine landslides are characterized by apparent geomorphology and sedimentary structures. In cross-sectional seismic lines, sublacustrine landslides are recognized by presence of mounded external configuration, chaotic or transparent seismic reflection. The head of landslides has well developed extensional fault, whereas in the toe region of landslides occurred compressive structures and thrust faults. Additionally, press ridges are also common in the toe region of landslides. Besides structless and turnover block aspects, key features of landslides are the common presence of deformational structures or soft-sedimentary deformation.
Sandy sublacustrine landslides can not only serve as conventional reservoirs at a lake center, but also are one type of favorable targets for deep hydrocarbon exploration, inasmuch as it developed a large quantity of the internal cracking caused by extensional and compressive force. Commercial oil &gas production has been received in the sublacustrine landslide, and which is expected to become a new field for deep hydrocarbon exploration.