Fault characteristics and controls on hydrocarbon accumulation in Changling Faulted Depression, Songliao Basin

Multiple types of oil and gas reservoirs have been found in the Changling Faulted Depression, and the reservoir types and pool size are variable in different areas. Fault characteristics, forming mechanisms and activity periods were studied based on seismic interpretation. The fault controls on hydrocarbon accumulation were discussed, and the main exploration targets in different areas were identified. Three types of fault were formed during the fault, depression and inversion periods. Under a NNE direction sinistral strike-slip and tension stress background, many NE, NS-NNW and NW direction secondary faults were generated. The fault activity characteristics varied in different areas. Due to fault activities, multiple types of structural traps were formed. The faults have a great influence on oil and gas migration and accumulation in the Changling Faulted Depression. In the areas that the faults are inactive and the tectonics are stable during the depression and the inversion periods, primary reservoirs were well preserved. As a result, the primary reservoirs in the Huoshiling, Shahezi and Yingcheng formations are main exploration targets. The secondary reservoirs are important exploration directions for the long duration of fault activity, especially in the deep faults and strike-slip faults.