Deep Structure of the Gippsland and Bass Basins (Project 9131.12). Operational Report for Cruise 1 (Survey 82)

Petroleum exploration within the Gippsland Basin has been focussed on major anticlines at the Early Tertiary "top Latrobe"unconformity, and to a much lesser extent on "intra-Latrobe" traps. Little information exists on the petroleum potential deep within the basin. Similarly, in the adjacent Bass Basin, most of the exploration effort has been concentrated at or near the top of the Latrobe Group equivalent, the Eastern View Coal Measures.

Analysis of regional seimic data collected by BMR in 1982 suggests that the Bass and Gippsland Basins were initiated by NNE-SSW lithospheric extension, probably in the Early Cretaceous. A reactivation of these basin-forming extensional structures, particularly transfer faults, may have had a significant influence on petroleum migration and accumulation higher in the stratigraphic section.

This operational report describes the first of two cruises to be undertaken by the R/V Rig Seismic in the Gippsland/Bass region(Nov - Dec.1988 & March - April 1989). These cruises aim to:
(i) improve definition of the deep structure of the Gippsland and Bass Basins using basin-wide deep seismic (12+ seconds) transects,
(ii) evaluate models for basin evolution
(iii) develop concepts for petroleum migration andentrapment from the regional data and by analogy with the similar basins worldwide, and
(iv) through the provision of regional seismic data assist the petroleum industry in carrying out seismic correlations.

The cruises contribute to a number of studies by BMR of the structure, stratigraphy, evolution and resource potential of offshore basins along Australia's southeastern margin.

This first cruise (Survey 82) was broken into four parts:
(1) Equipment testing for future work: involving the measurement of drift on a HIfix radio navigation system, and testing IFP electronics for the deep recording objectives of the program,
(ii) Recording of approximately 470 km of relatively deep-water reflection profiles in the eastern Gippsland Basin (12s records, 52.4 litre air-gunarray for Line 82/001 , 26.7 litre for lines82/002 & 3).
(iii) Recording of 1090 km of seismic reflection profiles in a grid over the Boobyalla Sub-basin of the Bass Basin (mainly 10s records, 26.7litre air-gun array).
(iv) Shooting of 2 x 200km refraction lines across the central part of the Gippsland basin from Deal Island to the Victorian coast.

吉普斯兰盆地（Gippsland Basin）内的石油勘探长期以来主要聚焦于早第三纪（Early Tertiary）“拉特罗布顶部”不整合面处的大型背斜构造，仅在较小程度上针对“拉特罗布层内”圈闭开展工作。目前关于该盆地深部的油气潜力信息寥寥无几。同样，在毗邻的巴斯盆地（Bass Basin）中，绝大多数勘探工作均集中于拉特罗布群等效地层——东望煤系（Eastern View Coal Measures）顶部或其附近区域。
对1982年由BMR（澳大利亚矿产资源局，Bureau of Mineral Resources）采集的区域地震数据进行的分析表明，巴斯盆地与吉普斯兰盆地大概率形成于早白垩世（Early Cretaceous）的NNE-SSW向岩石圈拉伸作用。这些控盆伸展构造（尤其是转换断层）的重新活化，可能对地层上部的油气运移与聚集产生了显著影响。
本作业报告介绍了R/V Rig Seismic勘探船计划在吉普斯兰/巴斯海域开展的两次科考航次中的首次航次（航次时间为1988年11-12月与1989年3-4月）。本次航次的目标包括：(i) 通过全盆地范围的12秒以上深层地震测线剖面，明确吉普斯兰盆地与巴斯盆地的深部构造形态；(ii) 评估盆地演化模型；(iii) 基于区域地震数据并类比全球同类盆地，建立油气运移与圈闭模式；(iv) 通过提供区域地震数据，助力石油工业开展地震对比工作。
本次航次将支撑BMR开展的多项研究，研究对象为澳大利亚东南缘近海盆地的构造、地层、演化过程与资源潜力。
本次首次航次（编号为82勘探）分为四个阶段：(1) 未来作业的设备测试：包括HiFix无线电导航系统（HIfix radio navigation system）的漂移测量，以及针对本项目深层记录目标的IFP电子设备测试；(ii) 在吉普斯兰盆地东部采集约470千米的较深水反射剖面（采用12秒采样记录，82/001测线使用52.4升气枪阵列，82/002与003测线使用26.7升气枪阵列）；(iii) 在巴斯盆地布比阿拉次盆地（Boobyalla Sub-basin）的网格区域内采集1090千米的地震反射剖面（主要采用10秒采样记录，配置26.7升气枪阵列）；(iv) 横穿吉普斯兰盆地中部，从迪尔岛至维多利亚海岸的2条总长各200千米的折射测线采集工作。