Geoscience Australia Marine Survey GA0332 (SS05/2011): Natural hydrocarbon seepage survey of the offshore northern Perth Basin - Sediment oxygen demand measurements from seafloor sediments.

In September and October of 2011 Geoscience Australia surveyed part of the offshore northern Perth Basin in order to map potential sites of natural hydrocarbon seepage. The primary objectives of the survey were to map the spatial distribution of seepage sites and characterise the nature of the seepage at these sites (gas vs oil, macroseepage vs microseepage; palaeo vs modern day seepage) on the basis of: acoustic signatures in the water column, shallow subsurface and on the seabed; geochemical signatures in rock and sediment samples and the water column; and biological signatures on the seabed. Areas of potential natural hydrocarbon seepage that were surveyed included proven (drilled) oil and gas accumulations, a breached structure, undrilled hydrocarbon prospects, and areas with potential signatures of fluid seepage identified in seismic, satellite remote sensing and multibeam bathymetry data. Within each of these areas the survey acquired: water column measurements with the CTD; acoustic data with single- and multi-beam echosounders, sidescan sonar and sub-bottom profiler (sidescan not acquired in Area F as it was too deep in places); and sediment and biological samples with the Smith-McIntyre Grab. In addition, data were collected with a remotely operated vehicle (ROV), integrated hydrocarbon sensor array, and CO2 sensor in selected areas. Sampling with the gravity corer had limited success in many of the more shallow areas (A-E) due to the coarse sandy nature of the seabed sediments. This dataset comprises sediment oxygen demand measurements from the upper 2 cm of seafloor sediments.

2011年9月至10月，澳大利亚地质科学局（Geoscience Australia）对珀斯盆地（Perth Basin）北部近海区域的部分区域开展调查，旨在绘制天然烃渗漏的潜在点位分布图。本次调查的核心目标是基于以下三类特征，绘制渗漏点位的空间分布并表征各点位渗漏的性质（气体与油类、宏观渗漏（macroseepage）与微观渗漏（microseepage）、古渗漏（palaeo seepage）与现代渗漏）：水体、浅层地下及海床的声学特征；岩石、沉积物样本及水体中的地球化学特征；以及海床上的生物特征。调查覆盖的潜在天然烃渗漏区域包括已证实（经钻探）的油气聚集区、一个破裂构造区、未钻探的油气远景区域，以及地震、卫星遥感和多波束测深（multibeam bathymetry）数据中识别出具有潜在流体渗漏特征的区域。在每个上述区域内，调查获取了以下数据：通过温盐深仪（CTD）进行的水体测量数据；通过单波束与多波束回声测深仪、侧扫声呐（sidescan sonar）及浅地层剖面仪采集的声学数据（F区因局部水深过大未采集侧扫声呐数据）；以及通过史密斯-麦金太尔采泥器（Smith-McIntyre Grab）获取的沉积物与生物样本。此外，在选定区域还通过遥控潜水器（ROV）、集成烃传感器阵列及二氧化碳（CO₂）传感器采集了数据。重力取样器（gravity corer）在多数较浅区域（A-E区）的取样效果有限，原因是海床沉积物为粗砂质。本数据集包含海床表层2厘米沉积物的沉积物需氧量（sediment oxygen demand）测量数据。