Deep Structure of the Joint Development Zone and Adjacent Areas, Timor Sea : Survey 116 Post-cruise Report

The primary objective of AGSO Survey 116 was the acquisition of high-quality deepseismic data and other geophysical data over the Indonesian - Australian JointDevelopment Zone (JDZ) and adjacent areas of the Timor Sea. The cruise was partof a program being undertaken by AGSO, to determine the structural architecture ofthe north western margin of Australia and the influence of structuring on the location,migration and trapping of hydrocarbons in the region. The survey vessel R.V. Rig Seismic left Darwin on 22 January 1993 but returned toport on 30 January due to equipment problems and poor weather conditions. Theship again departed Darwin on 3 February and began seismic acquisition on 5February. The survey was completed on 7 March and finished in Darwin on 8 March. During the survey, 16 seismic lines were completed for a total of 3595 km at anaverage of 119 km per day. All of the proposed Timor Sea Tie lines were completed,however lines across Zone of Cooperation C of the JDZ and the Timor Trough inIndonesian waters were not collected because an agreement between AGSO andIndonesian authorities had not been finalised. In addition to the proposed program,the survey included 5 lines of the Malita Graben program, totalling 1028 km. TheseN-S lines were shot when marginal weather conditions prevented seismic acquisitionin an E-W direction. The Timor Sea Tie lines were tied to 17 exploration wells. Acquisition within the Joint Development Zone was undertaken on behalf of NOPEC,who have been authorised by the Joint Development Authority to research this area.All seismic lines were collected to specifications agreed upon by NOPEC and AGSO. The seismic data were recorded from a 4800 m streamer, configured with 192 x 25 mactive groups. The record length was 16 seconds, and the sample interval 2 ms.The seismic source consisted of dual sleeve gun arrays with a capacity of 50 litres.Navigation for the survey was provided by differential Global Positioning System(dGPS), using shore reference stations Darwin and Broome. The seismic acquisition system was inoperable during the first week at sea duringwhich time weather conditions also prevented acquisition. After repairs to thesystem, both the seismic and non-seismic acquisition systems ran without majorproblems. Navigational data were of good quality, with differential GPS beingavailable at least 95% of the survey time.AGSO（澳大利亚地质调查组织，Australian Geological Survey Organisation）勘探项目116的核心目标，是在印尼-澳大利亚联合开发区（Joint Development Zone，JDZ）及帝汶海周边区域采集高质量深部地震数据与其他地球物理数据。本次航次是AGSO实施的项目的一部分，旨在明确澳大利亚西北陆架的构造架构，以及构造作用对该区域油气的赋存、运移与圈闭的影响。 勘探船“雷格地震号”（R.V. Rig Seismic）于1993年1月22日从达尔文港起航，后因设备故障与恶劣海况于1月30日返港。该船于2月3日再次从达尔文港出发，并于2月5日启动地震数据采集工作。本次勘探任务于3月7日完成，并于3月8日返回达尔文港。 本次勘探共完成16条地震测线，总长度3595千米，日均采集119千米。所有预设的帝汶海联结测线均已完成，但因AGSO与印尼官方尚未敲定相关协议，未能采集JDZ合作区C以及印尼海域内帝汶海槽的对应测线。除预设项目外，本次勘探还额外完成了马里塔地堑项目的5条测线，总长度1028千米。当恶劣海况导致东西向地震采集无法进行时，作业团队启动了该批南北向测线的采集工作。帝汶海联结测线与17口勘探井完成联测。 联合开发区内的数据采集工作由NOPEC委托开展，该机构已获得联合开发当局授权对该区域进行研究。所有地震测线均按照NOPEC与AGSO共同商定的技术规范进行采集。 本次采集的地震数据由长度4800米的地震拖缆记录，该拖缆配置有192组×25米的有效接收道组。数据记录时长为16秒，采样间隔为2毫秒。地震震源采用总容量50升的双套筒气枪阵列。本次勘探的导航服务由差分全球定位系统（differential Global Positioning System，dGPS）提供，采用达尔文与布鲁姆的岸基参考站。 出海首周，地震采集系统无法正常运行，同时恶劣海况也导致无法开展采集工作。完成系统维修后，地震与非地震采集系统均未再出现重大故障。导航数据质量优异，差分GPS在整个勘探周期内的可用率不低于95%。