南黄海西部地区浅层气成因

Origin of shallow gas in the western region of the South Yellow Sea

通过研究近年来获取的浅地层剖面发现,南黄海浅层气主要存在于南黄海东经123°以西的地区,为此进行了该区浅层气成因分析,以探索其来源。将根据南黄海西部地区逾6000km的浅地层剖面解释成果得到的南黄海西部地区浅层气分布概况,与该地区的有机质分布状况进行了对比分析,认为南黄海西部晚更新世末期的泥炭分布与浅层气分布具有较好的一致性,表明晚更新世末期的泥炭是该地区浅层气生成的重要物质基础。3个声学空白区的浅层气可能来自中深部地层。苏北浅滩西北部的大型塌陷坑可能由浅部断层活动引起的浅层气在该处多点喷发形成的塌陷坑复合而成,表明该处中深部地层中可能存在天然气。南黄海中部声学扰动区内浅层气不断自海底逸出,该处断层较多,中深部地层具备生气能力,推测该地区浅层气可能是深部油气泄露的气苗。

Shallow seismic data acquired in recent years reveal that shallow gas mainly occurs in areas to the west of the longitude 123°E in the South Yellow Sea. The origin of shallow gas in the study area is analyzed. The shallow gas distribution defined based on interpretation of the shallow seismic data over 6000km in the western region of South Yellow Sea basin is correlated with the distribution of organic matter in the same area. It is revealed that the distribution of the Late Pleistocene peat correlate well with the distribution of shallow gas in the study area,indicating that the Late Pleistocene peat is the major source of shallow gas. The shallow gas contained in three acoustic blank zones may be sourced from the middle-deep strata. The large collapse crater in the northwestern part of Subei shoal may be a composite collapse crater resulted from shallow-faulting-related multipoint eruption of shallow gas,indicating that the shallow gas may occur in the middle-deep strata. In the central region of South Yellow Sea basin,shallow gas continuously escapes from the sea floor in the acoustic disturbance zones where faults are well developed. The middle-deep strata are capable of generating gas. It is predicted that the shallow gas in this area may be gas seepages coming from the deep.