Identification method of Ordovician ancestral river system in Halahatang area, North Tarim Basin

Ancestral river system played an important role in controlling karst carbonate reservoir development. Combinating fine recognition of ancestral river can predict the advantageous Karst reservoir distribution regions. In the actual research, firstly, identifying the ancestral river which possess the characteristic of “incised valley” through the seismic profiles, and makes clear the two main growth stages of ancestral river are Lianglitage formation and Sangtamu formation. Then calculate the 3D seismic data with eigenvalue coherence algorithm, make coherent stratal slices of the two stages channel, and the results showed that two stages channel development and location has a certain inheritance character. In the period of Lianglitage formation, the Channel width is large and low-sinuosit, while in the period of Sangtamu formation, the Channel width is small and high-sinuosity. Closeness to the channel Karst carbonate reservoir developed with moniliforme reflection characters.