Characteristics of hydrocarbon plays in faulted formations, Changling Fault Depression, southern Songliao Basin

The sedimentary fill of the Changling Fault Depression in the southern Songliao Basin has the dual characteristics of "volcano-sedimentation". There are many types of hydrocarbon plays with a low degree of exploration in the faulted formations of the Changling Fault Depression. The major plays are different from one structural zone to another. Starting from the classification of hydrocarbon plays and exploring the reasons for distribution differences, we analyzed the characteristics, distribution rules and main controlling factors of hydrocarbon accumulation in volcanic rocks and tight clastic rocks in the study area. Based on the above findings, we established three pool-forming patterns. (1) The near-source, near-crater subfacies, fault transport, regional caprock, and inherited paleo-uplift jointly controlled the oil and gas enrichment in the volcanic rocks in the Yingcheng Formation. (2) Direct caprock, unconformity-fracture composite transport, near-source, inherited slope zone (super-stripping zone) jointly controlled the hydrocarbon accumulation in the clastic rocks in the Yingcheng Formation. Advantageous facies belt, inverted tectonic belt/slope break zone, burial depth, reasonable arrangement of sand body and oil source fault and regional caprock jointly controlled self-generated and self-storing tight oil and gas enrichment in the Shahezi Formation. Based on the analysis of the main controlling factors of hydrocarbon accumulation, the key parameters and standards of oil and gas evaluation for different types of hydrocarbon plays were proposed. It was pointed out that the volcanic rock plays of the Yingcheng Formation in the Chaganhua area, the tight clastic rock plays of the Yingcheng and Shahezi formations in the Longfengshan, Dongling and Fulongquan area are the key exploration directions.