Discussions on the relations between sedimentary accommodation space change and oil-gas collective system in terrestrial fault-depressed basins

The rules of the sedimentary accommodation space changes in terrestrial fault-depressed basin control the sequence stratigraphic filling patterns and the development rules of generating-reservoir-cover assemblage. Based on the sequence stratigraphic response characteristics of the terrestrial fault-depressed basins in China, the change frequency of sedimentary accommodation space is divided into two types:lower frequency and higher frequency. Oil-gas collective systems are the main research objects in the oil-gas exploration of terrestrial fault-depressed basin. On the basis of the oil-gas accumulation scale, the oil-gas collective systems are divided into three types:great, middle and small ones. Commonly, the terrestrial fault-depressed basins with different sequence stratigraphic filling patterns develop different scale oil-gas collective systems with corresponding spatial distribution rules. Lower frequency sedimentary accommodation space change in terrestrial fault-depressed basins will develop oil-gas collective systems with great scale or middle scale while the higher frequency sedimentary accommodation space change will develop oil-gas collective systems with middle scale or small scale, the great scale oil-gas collective system developed rarely. In the continental China, Dongying depression is the typical representative of terrestrial fault-depressed basins with lower frequency sedimentary accommodation space change, and the Dongpu depression represents the higher frequency sedimentary accommodation space change. In the oceanographical area, the Weixinan depression belongs to the type of the lower frequency sedimentary accommodation space change, and the Haizhong depression belongs to the type of higher frequency sedimentary accommodation space change.