澳洲北卡那封盆地深水区三叠系异常体识别

北卡那封盆地东北部的比格坳陷深水区勘探程度低,三叠系发现的小天鹅异常岩性体既具有发育碳酸盐岩生物礁的古构造背景,但同时也不排除该地质异常体为火成岩的可能性。针对这个异常体是火成岩与生物礁的辩证识别,探索形成了一套“相面、解体、寻根、溯源”四步法深水无井区异常体识别分析技术。第一步是“相面”,在全三维地震资料精细解释的基础上,综合利用地震属性分析、地震相分析识别特殊异常体的形态;第二步是“解体”,综合利用波形聚类、三维可视化等技术精细解剖异常体结构;第三步是“寻根”,提取异常体所产生的重、磁异常特征,结合重、磁、震联合反演技术,推断异常体的岩性及规模;第四步是“溯源”,通过古构造恢复及岩相古地理分析重构异常体形成环境,调研区域火山活动特征,判定火山活动期次及时间。最终认为小天鹅特殊异常体为火成岩的概率较大,并识别出特殊异常体火山通道相、火山侵入相、溢流相、火山碎屑沉积相等重要地震相特征。这套深水无井区异常体识别分析技术在无井、仅有三维地震资料的深水区具有较好的应用效果,可以在勘探初期较好地对异常体进行甄别,减少钻井投入。

Identification of a Triassic anomaly in deep water of Northern Carnarvon Basin,Australia

The deep-water area of the Beagle Depression in the Northern Carnarvon Basin is at an early exploration stage. Cygnet anomaly, which was found in Triassic strata, has not only the paleotectonic background of developing carbonate reefs, but also the possibility of being volcanic rocks. In order to distinguish whether the Cygnet anomaly is volcanic rock or reef, a set of four-step analytical techniques was applied in this area. (1) Seismic facies analysis. Based on the interpretation of 3D seismic data, comprehensive seismic attributes as well as seismic facies, the shape of the Cygnet anomaly was identified. (2) Inner structure analysis. The inner structure of the Cygnet anomaly was dissected by using waveform clustering and 3D visualization techniques. (3) Gravity and magnetic analysis. The gravity and magnetic properties of the Cygnet anomaly were identified by carrying out gravity and magnetic seismic inversions. (4) Regional volcanic activity analysis. Combined the restoration of paleo-structure, the analysis of lithofacies paleogeography and the investigation of regional volcanic activity, the volcanic activity period and time were confirmed. Finally, it was concluded that the probability that the Cygnet anomaly is igneous rock was high, and some important seismic facies such as volcanic channel facies, volcanic intrusive facies, overflow facies and pyroclastic sedimentary facies were identified. This set of anomalous body identification technology in a pre-drilling deep-water area has a good application. It can identify anomalous body characteristics in the early exploration stage and optimize drilling investment.