Acoustic detection of seabed hydrocarbon seepage in the north depression of South Yellow Sea Basin

The full-covered Side-Scan Sonar and high-resolution seismic survey method is initially used to research on the seabed hydrocarbon seepage in the survey area, for the purpose of the following: clarifying the shallow acoustic features related to seabed hydrocarbon seepage in the north depression area of South Yellow Sea Basin, analyzing the relations between the seepage and the structure, and providing evidence for selection of geochemistry sampling station and petroleum exploration. On the mosaic image of Side-Scan Sonar, the strong reflecting spots in strip-like distribution present the physiognomy of pockmark and dome. On the seismic profile, we can see the characteristics, such as enhanced amplitude, columnar disturbance, gas chimney, and blank reflection, which result from gas accumulation. The analysis results indicate that the widely developed faults that approach or connect to seabed provide the channel and source of hydrocarbon seepage. The accumulation and seepage of subsea shallow-layer gas results from the upward migration of fluids from deep-layer pores, and the sub-sea survey area is still at tiny seepage stage.