10th November 2017
Latest Efficiencies in Marine Acquisition
Last week saw the latest round of Shearwater Lunch and Learn sessions in the UK – a series of talks given internally by senior staff on a topical issue, with the addition of pizza. My talk was titled, ‘Latest Efficiencies in Marine Acquisition’ – a subject that has been critical to the on-going success of Shearwater. My audience ranged from Seismic Processors (land and marine) to Researchers, Salespeople and even HR. The seismic marine acquisition industry has gone through a rapid change over the last few years in order to meet the lower costs required by clients whilst maintaining the highest standards in QHSE. I chose three cases that have demonstrated the increased efficiency in acquisition with the emphasis on how these have only been possible with the advanced development in processing technology.
First up was Fresnel zone analysis and how it can reduce infill on a survey. I went through the basic concepts with just minimal equations and demonstrated how conventional flexing for coverage analysis can be expanded. The justification comes from the analysis which shows that a trace’s mid-point usually has a larger area of influence than a bin. I displayed some results from a recent survey where infill was 3% as opposed to 9% if infill was analysed conventionally. The implication for processing is a drop in un-flexed coverage. As most migration algorithms require a regularised input this lowering in coverage can only be handled with the appropriate regularisation technology.
Second was a case study of seismic interference and how it has evolved from rejecting data, to time share, to partial attenuation, and more recently forward simulation and cooperation. The simulation forward projects boat positions and aims to minimise the most unwanted interference based on move-out and amplitude by making small adjustments to speed and turns. I presented a case where we were one of four boats acquiring data in the same area and where all contractors were coordinated by an independent third party who ran the simulation. Each boat’s program was completed with 0% down time for interference when traditionally in the area it is up as high as 15% - a huge saving on costs. The acquired data still had interference to be removed but with robust online QC and full processing, the unwanted recordings were attenuated.
Lastly I presented Shearwater’s latest acquisition offering – FlexiSource. FlexiSource is a combination of multiple, overlapping sources, continuous recording and advanced de-blending techniques. All these can provide increased acquisition efficiency and higher trace density on 3D surveys. I went through some basic geometry and visualisation of how it looks. I presented a case from this summer where we acquired a large high resolution 5500 sq. kms survey in a single season. The dataset was of very high fold with small, 12.5 x 6.25 m bins. Without FlexiSource this particular survey would have had to have been acquired either over two seasons or with 18 streamers. Neither alternative was desirable to the client for timing, logistical and geophysical reasons.
As a full service seismic company Shearwater understands and actively drives efficiencies in the industry. A combination of modern boats and equipment, in-house processing, R&D and REVEAL software, run by a fully focused team makes Shearwater an industry leader.
The old doddlebugger’s adage of, ‘processing will sort it out’ is more appropriate than ever. As the only seismic processing software in the world designed and built entirely in the 21st century, Shearwater REVEAL is ready to deal with any dataset, past, present and future.
Lunch and learn is one small part of Shearwater’s focus culture program, in this case bringing people together to learn what goes on in the whole company whist enjoying a pizza.
Email firstname.lastname@example.org to find out how Shearwater can Reveal the Possibilities for you.
Jonathan Pollatos, Offshore Processing Manager