Evidence analysis of natural gas near-source migration-accumulation model in the Sulige large gas province, Ordos basin, China

Sulige gas province is a typical large unconventional continuous tight gas province, and studying the natural gas distribution and accumulation characteristics of this area is of great significance to unconventional tight gas geological research and integral exploration in China. Evidences from geochemistry, reservoir geology and paleo-tectonic background all verify that, the situation of natural gas distribution and accumulation present day in Sulige area is the result of the near-source migration-accumulation. Geochemistry evidence; Natural gas is mainly distributed in areas with higher gas-generating intensity, gas compositions don' t suffer obvious processes of fractional distillation, gas-bearing saturation decreases away from the coal measures, and the isotopes of gas compositions is consistent with the source and maturity of the coal measures. Reservoir geological evidence; Intense compaction, quartz cementation and carbonate cementation led to the formation of the tight reservoirs before the main gas accumulation stage. Paleo-tectonic evidence; From the main gas accumulation stage to present-day, the paleo-tectonic slope kept in gentle, without formation conditions of higher vertical continuous gas column.