b'Seismic window Seismic windowMichael MicenkoFigure 1.Example vibroseis source array of the 1980s. At each source location three vibrators would Associate Editor for Petroleum sweep simultaneously then move along the line until four sweeps (1-4) were recorded. These were then mick@freogeos.com.au stacked and correlated to give a single record for the shot point. It is easy to make a simple adjustment to record every sweep individually and sum traces to form appropriate arrays. Note: Receiver groups are centred on the station while source arrays are between stations. This is to maximise the benefits of stacking.Point source acquisitionMy home office was recently invaded byexample source and receiver layout isare the norm (or should be) with crews water leaking through the ceiling andshown in Figure 1, and it is easy to seeequipped with thousands of channels. while I was moving things to safety, Ihow the vibrator array could be changedWe no longer have to design arrays stumbled across a technical brochureslightly to record each sweep separatelyto minimise noise because the close published by GSI in 1984. It was titledwhile simultaneously saving summedreceiver spacing is sufficient to model the GSI single sweep recording. Back inrecords. To maintain the sweep timenoise and remove it in processing. As it the eighties, a typical vibroseis seismicper kilometre the sweep length wasturns out, random noise is not so random crew had 48 channels (maybe 96 atshortened while the number of sourceafter all. The increased fold allows better best) and receivers were planted in anpoints is increased more sweeps butvelocity analysis and improved residual array of up to 50 m length. Each sourceshorter sweeps. statics both of which result in a better point consisted of three vibrators instacked section.Recording single sweeps was a novel line with four sweeps of 12 seconds atconcept that we would not think twiceWith so many channels available the regular intervals between the receiverabout today, but this was all new in 1984current trend is to move away from stations. These parameters were devisedand single sweep recording requiredcables and use cableless recording to reduce noise in the 12 fold data andimproved instrumentation such assystems that are standalone and record were a massive effort. More vibratorshigher density tape drives and real timecontinuously for a month on a single boosted the signal, as did the numbercorrelation while also performing a stackbattery charge. These instruments are and length of sweeps, while usingof the correlated records. possible because of the development source and receiver arrays reduced theof low cost, low power GPS chips used amplitude of horizontally travelling noise.Coincidentally, this week I attended anto locate the receivers, and also provide The GSI brochure suggested the effortindustry presentation about Challengingaccurate timing. Simple, but harvesting could be redistributed as continuousLand Surveys. Apparently land surveysthe data from so many individual boxes equally spaced source points withoutstill have challenges. Today closelyand formatting it appropriately may take adversely affecting production rates. Anspaced point source and point receiversseveral days.The ASEG in social mediaHave you liked/followed/subscribed to our social media channels? We regularly share relevant geoscience articles, events, opportunities and lots more. Subscribe to our Youtube channel for recorded webinars and other content. Email our Communications Chair Mosayeb K. Zahedi at communications@aseg.org.au for suggestions for our social media channels.Facebook: https://www.facebook.com/AustralianSocietyOfExplorationGeophysicistsLinkedIn company page: https://www.linkedin.com/company/australian-society-of-exploration-geophysicists/Twitter: https://twitter.com/ASEG_newsYouTube: https://www.youtube.com/channel/UCNvsVEu1pVw_BdYOyi2avLgInstagram: https://www.instagram.com/aseg_news/ DECEMBER 2022 PREVIEW 40'