AutoSeis in Finding Petroleum

June 10th, 2011 | tags: Board Services

AutoSeis – simple wireless seismic recording

Friday, June 10, 2011 in Feature Articles

AutoSeis of Carrolton, Texas has gone for a simple approach with its wireless land seismic recorders; the data is stored on the field units
(High Definition Recorders – HDR) and gathered later.

For land wireless seismic recording devices, you’re much better off storing the data on the unit itself rather than sending it back to a central unit in real time, according to Ralph Muse. Ralph is the President of AutoSeis, a Global Geophysical Company, that develops seismic recording equipment.

“Everything must be as simple and reliable as possible,” he says. “We don’t have complex radio systems. You put the units out and they stay there for weeks, and then bring them back to camp.  By keeping the units simple and low cost, it is easy to provide redundant units and over sample the survey.”

Mr Muse is an expert on radio data communication. He was CEO of NextNet Wireless which was acquired by Motorola in 2006; he was also was COO of the wireless internet company Metricom Inc, and Senior Vice President of land seismic imaging at Input Output (since renamed ION), a company also specializing in wireless land seismic recording.

Given his background in wireless data communications, it is ironic that he has chosen not to include radio data links in the HDR.  Mr Muse attributes this decision to his experience with other wireless systems. “Out in the field, there are always problems, and places you can’t communicate,” he says. “It complicates operations for no real reason. I would hate to be the field operators tasked with maintaining a complex communication infrastructure in difficult terrain.”

“When you start trying to connect thousands of units, it is very complicated, and takes up a lot of bandwidth. It’s a problem in scaling. I don’t know what happens when you try to do mesh networks for tens of thousands of units, and I don’t want to find out.”

For example, Mr Muse said he worked with a wireless seismic system which required a radio contact to be made with every unit before shooting began. “Some of them are in ditches, some of them are behind a hill. It’s hard to get a connection to every one, so you end up having a lot of problems, and have to set up relay transmitters to make sure you have all the connections.  You’ve traded cable maintenance for communication system maintenance; so what have you gained?”

Companies often have radio licensing problems, discovering that a technology they can use legally in one country at a certain frequency can’t be used in another part of the world.

AutoSeis

RDSeismic LLC was founded in late 2008 by Ralph Muse, Initial product launch and field testing were completed in spring 2010. RDSeismic was acquired by seismic service provider Global Geophysical Services Inc. of Houston, in Nov. 2010. The company was then renamed AutoSeis Inc.

“Global Geophysical used three other wireless seismic systems,” Mr Muse says. “They realized it made sense to own their own supplier. They can have their own technology and customise it the way they want.”

The company is currently building its first 10,000 HDR units, with a further order for 28,000 units, to be exclusively used by Global Geophysical to provide seismic surveys for its customers.

The company is also developing an ocean bottom seismic recording system using the same HDR technology.

The system

The core of the AutoSeis system is the HDR unit, which is “about the size of an iPhone,” Mr Muse says. It weighs just 3/10th of a pound (136g). The unit usually has a 20amp hour lithium battery, which weighs about 2.9lb (1.3kg).

To set up a survey, you decide which specific times you would like the units to record in advance (eg weekdays 6am to 8pm) and program that into the unit, along with the sample rate and tell it what type of geophone you will use. Then you drive out to the field, place the units in position, record their locations and start shooting.

To download the data afterwards, you plug the units into a special rack which can take about 20 units at once. The software automatically downloads the data, uploads programming for the next survey, and checks if the software needs updating. All of this takes about 2 minutes, so by the time you have inserted 20 units into the downloading rack, the first one is ready to be removed.

The unit contains a custom microchip, GPS, clock, motion sensor, infrared communications device and 8 gigabytes of data storage.

The system has one circuit board, and is fitted in a plastic case completely filled with resin. “You don’t have to worry about water getting in because it is full of resin,” he says. “These units are tough, you can run over them without damage.”

The system records in 32 bits, with 26-27 of those bits actually available for seismic processing, which means it can get a dynamic range of around 160dB, Mr Muse says. This compares to 120-140 dB range for 24 bit recording systems. “Our noise floor is a lot lower,” he says. “You can see data you clearly could not see otherwise.”

The 8gB of memory storage onboard is enough to store 85 (12 hour) days of data at a 2 millisecond sample rate, so data storage capacity is not an issue.

The unit also contains an accelerometer (similar to the iPhone). When the unit is moved to another location, the accelerometers detect that it has been moved, and that it needs to start a new record for the new location.

The HDR units can also communicate by infrared, so you can interrogate them with a laptop in the field without cabling them up.

All the units have barcodes. When they are being laid out in the field, the surveyor has a hand held device also containing a GPS which can scan the barcode, so the computer system knows which device it is and where it is.

While in the field, the units can be connected to radio communications if desired, for example if you check if there is background noise (for example from a train or farm equipment) close to receivers which are out of your line of sight, which might make the recording useless. But you don’t need to monitor each individual unit.

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