“Tri-in-One” Accumulation Model of Lithologic Reservoirs in Continental Downfaulted Basins: A Case Study of the Lithologic Reservoir of Nantun Formation in Tanan Sag, Mongolia

This article analyzes the key controlling factors and hydrocarbon distribution rules of lithologic reservoirs in a continental downfaulted basin according to structural features, sedimentary evolution, types facies, source rock diagenesis reservoir formation mechanisms, exploration status, resource potential. The results show that three major (sandbody types, effective rocks, reservoirs) one coupled factor (fractures act as tie) influence accumulation traps Nantun Formation Tanan Sag. With increase depth, sufficient is generated with thermal evolution. When depth threshold reached critical conditions supply are met, generation expulsion more intensive. Traps surrounded or contacted by connected faults able form reservoirs. As buried increases, intensity generation–expulsion grows, trap petroliferous. Hydrocarbon also controlled sandbody conditions. for met concrete oil gas charged in, better physical properties will always indicate trap. allocation sand type, rock, an optimized under effect fractures these elements.