杭州湾北部海底天然气的浅地层剖面测量调查

Measurement of Shallow Stratigraphic Sections for Seabed Gas Exploration in Northern Hangzhou Bay

利用浅地层剖面测量，对杭州湾北部地区的海底浅层天然气进行了调查与分析。探测结果呈现空白与幕状屏蔽、柱状扰动，顶界面不规则、两侧相位下拉等特征，显示该区域存在大量浅层天然气。分析结果表明：调查区域内的海底天然气整体埋藏较浅，深度通常在15--25m之间，赋存于中全新统砂层中，为甲烷型生物气，气体压力不大，属自生自储类型。圈划出了海域浅层气分布范围。成果可为未来海洋工程建设和浅层气灾害防治提供依据。

The measurement of shallow stratigraphic sections was used to investigate seabed gas in northern Hangzhou Bay. The results show various characteristics including blank and tentiform shielding, columnar disturbance, irregular top interfaces, and both sides of phase drop-down, which together indicate a large volume of shallow gas in the studied area. The analysis indicates that the buried depth of seabed gas in the area is relatively shallow, generally between 15 and 25 m beneath the seabed, and it occurs in the Holocene sand unit. The seabed gas is methane-type biogas; gas pressure is not high, and it is self-generated and self-stored. On the basis of the results, it will be possible to identify the distribution ranges of seabed gas in this offshore area. The findings should provide a basis for constructing ocean exploration engineering structures and for preventing shallow gas disasters.