Publications

Commencing August 2016 Ophir Energy led the acquisition of the Trepang 3D marine seismic survey south of West Papua in the Aru Trough area. The source and streamer design used was deep flat tow broadband, which gives the good low-frequency response required for the deep carbonate plays - the survey’s primary targets. The Trepang 3D survey acquired with a triple-source marine seismic design was a first for Indonesia. The cross-line resolution, important for data quality, is maintained or even improved upon with wide towing spreads when utilising three sources instead of the conventional two sources. For example, when compared to a traditional 25m cross-line bin acquisition with cables 100m apart and dual-sources to that of a triple source with 150m separations, while maintaining a cross-line bin size of 25m, a 50% increase per swath is achieved as compared to the conventional, a significant efficiency improvement with reduced operational and HSE exposure. Using triple sources reduces inline fold if conventional shot point intervals are kept to, which can cause problems in data processing. However, if the sources are fired more often, every 12.5m, rather than the 25m for a dual-source survey, this increases fold over the conventional and avoids the problem. The shorter time between shots means that the seismic record 5 seconds below the water-bottom has interference energy from the next shot, therefore, an extra stage of processing is required to remove this energy before conventional processing can commence. The Trepang survey was acquired with a reduced by two streamers to a 10x150m streamer setup due to operational conditions with floating debris, mainly tree logs, causing risk to in-sea equipment. Other than that the survey went according to plan and initial onboard processing results indicate that the expected final dataset will be of high quality. The triple source approach resulted in the notional survey duration being reduced by 30%, which matched the actual duration achieved.