Flash flood as an effective pebble transport mechanism: a case study from the Permian Sulige Gas Field, Ordos Basin, China

Pebbles up to 10 cm in diameter, as the main clastic component of gas reservoirs in the Permian Sulige Gas Field, deposited more than 150 km away from their northward provenance (Yinshan Mountains) in the northern Ordos Basin. The transportation and depositional mechanisms of these pebbles have been unclear for decades. Based on core examinations, facies analysis, and mathematical modeling (stress field calculation of pebbles), it is thought that (1) these coarse-grained deposits were transported and deposited in braided rivers; (2) the size of coarse-grained sediments and pebbles in the Sulige Gas Field is in accordance with the size of flash flood; (3) flash flood is regarded as a crucial important transporting mechanism of pebbles; and (4) the flash flood genesis braided river-braided delta sedimentary model provides a reasonable understanding for prediction of coarse-grained reservoirs for gas exploration not only in the Permian Sulige Gas Field but also in similar coarse-grained sediments elsewhere.