Yinggehai basin

The Yinggehai-Song Hong Basin is located on the northwest of the South China Sea, between Hainan Island and the coast of northern Vietnam.

Yinggehai basin is lies at the southern end of the Red River fault zone, located at the Gulf of Tonkin.

The slowly extrusion of the Indochina block without clockwise rotation resulted in the sedimentation in Yinggehai basin before 36 Ma.

The sinistral slip of the Indochina block caused pull-apart extension of the Yinggehai Basin, as well as the rapid clockwise rotation during 36 - 21 Ma.

[2] The sediments filled in the Yinggehai Basin came mostly from Tibet plateau and was transported mostly by the Red River, and the depocenter has migrated southward since the Oligocene.

The shale diapirs ( see figure 5) grew into the section, which is generally thought to be caused by the rapid deposition and resultant increase in over pressuring.

Within these sets, Neogen Lower-Middle Miocene littoral to neurotic mudstone is the mose important hydrocarbon source rocks, mostly distributed in the central diapir zone up to a maximum start thickness of 5,000 m with great than 70% shale content.

During this stage, the main products were methane form high-temperature cracking of kerogen and/or liquid hydrocarbon and CO2 from the inorganic carbonate decomposition.

Location of the Yinggehai-Song Hong Basin, marked by blue color.
Figure 2. Detailed isopach map for Yinggehai basin. Modified after Hoang et al., 2010 [ 5 ]
Figure 3. Stratigraphy column and source-reservoir-cap of the Yinggehai Basin. Modified after Wan et al., 2012 [ 6 ] and Lei et al., 2011. [ 7 ]
Figure 4. Reconstructed sediment budgets for the southern Yinggehai basin. modified after Clift et al., 2006 [ 1 ]
Figure 5. A Northwest-Southwest cross section shown the shale diaper in Yinggehai basin. Modified from Clift et al., 2006 [ 1 ]