Welcome to Petroleum Geology Forums

This is a free online community that aims to bring petroleum professionals and geologists together and share valuable knowledge. Registration is easy so become a member now for instant free access.
  • Petroleum Geologists can stay up to date with industry related topics and exchange ideas and concepts.
  • Upstream Oil and Gas Consultants get a chance to share their expertise and gain exposure to land future projects.
  • Geology students and graduates can join the discussion and get into contact with potential future employees.

  >> Register Now





Post new topic Reply to topic  [ 1 post ] 
Comparison of pseudo‐random binary sequence and... 
Author Message

Joined: Fri Mar 11, 2011 9:00 pm
Posts: 14670
Post Comparison of pseudo‐random binary sequence and...
Geophysical Prospecting: Comparison of pseudo‐random binary sequence and square‐wave transient controlled‐source electromagnetic data over the Peon gas discovery, Norway

We discuss the problem of source control in controlled‐source electromagnetic (CSEM) surveying and compare and contrast equal energy transient square‐wave and transient pseudo‐random binary sequence source signatures for the same towed‐streamer electromagnetic survey line over the Peon gasfield in the Norwegian sector of the North Sea. The received response of the transient square‐wave data was 11 dB greater than that of the pseudo‐random binary sequence data, due to diffusive attenuation of higher frequencies present in the more broadband pseudo‐random binary sequence signature. Deconvolution of the pseudo‐random binary sequence data recovers the total impulse response function, increases the signal‐to‐noise ratio by 32.6 dB and separates most of the air wave from the earth impulse response by the causality principle. The recovered impulse responses have more detailed information in the frequency domain than the transient square‐wave data. The pseudo‐random binary sequence data were acquired with a 10 Hz source bit rate but contain no information about the Peon gasfield at frequencies above 2 Hz. The bit rate could have been reduced to 4 Hz, increasing the signal energy below 2 Hz by 150% and thus, potentially, increasing the signal‐to‐noise ratio by a further 4 dB.Because the total earth impulse response can be recovered from the broad‐bandwidth pseudo‐random binary sequence data, further time‐domain processing may be applied, including correlated noise removal, which can increase the signal‐to‐noise ratio by as much as 20 dB, and air wave removal using the causality principle. The information in the arrival time of the peak of the earth response provides the potential for traveltime to resistivity mapping to provide a starting model for inversion.

Go to Article


Wed Sep 28, 2011 11:08 am
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 1 post ] 





Search for:
Jump to:  
cron


Content on EPGeology.com is intended for personal use only and to supplement, not replace, professional judgment. EPGeology.com disclaims any and all liability for your use of its content. As most of our content is supplied by our users we can not check copyright, and stress that copyright remains at the original owner. If you suspect copyright infringement please use the contact form to report it.
Contact || © EPGeology.com. || Powered by phpBB Asteroid Mining

phpBB SEO