In the latest version of RadExPro- RadExPro 2016.2- Deco have completely redesigned the main interface to make it even more intuitive. Processing modules can be linked graphically to produce complex relationships with flows. In addition a dedicated SEG-D revision 3 input module has been included, and 3 dimensional auto picking has been incorporated.
RadExPro is available for sale or rental form Geomatrix Earth Science. please feel free to contact us for a free trial.
Rental Pool Addition: EM61S coil
12 June 2016
As offshore UXO mitigation becomes more prevalent the demand for geophysical instrumentation for locating non-magnetic objects closure to the shore line has increased significantly. Working in the tilde zone is particularly challenging and traditional survey techniques and instrumentation is not ideally suited to the application. To address this specific issue Geomatrix have added an EM61S marine TDEM coil with 100m power data cable to the lease pool.
The coil can be mounted onto a sledge towed across the seabed. The sable sledge platform minimises the movement of the coil from the influence of swell and maintains a constant high above the seabed. In addition the EM61S is a Transient Electromagnetic system which can locate ferrous and non-ferrous objects.
Please feel free to contact us for further information and rental rates.
New features in SeisImagerSW
12 May 2016
SeisImager/SW-1D and -2D now include H/V Spectrum Analysis. With a seismograph and one 3-component geophone, recorded microtremor data may be processed to determine peak frequency for microzonation applications.
SeisImager/SW-Pro is also capable of integrating higher modes into the inversion process. Higher modes tend to dominate where there is a strong contrast between low and high-velocity layers or where there is a velocity inversion
Rental Pool Addition: GT-40 Gamma Ray Spectrometer
24 March 2016
The GT-40 is a versatile Gamma Ray Spectrometer which incorporates specific software and hardware features enabling it to be used for field surveys and follow up laboratory measurements.
GT-40 transportation/carrying harness. Image courtesy of Georadis.
Unlike other Gamma Ray Spectrometers currently on the market the GT-40 stores the complete calibration spectra to memory, meaning the operator can apply any standard coefficients and the instrument will calibrate itself. Calibrations can be defined for elements or compounds.
The GT-40 includes the ability to implement a local background reading for isolating counts from a particular sample. Combined with a sophisticated automatic gain function called Proportional Gain Compensation, for compensating temperature fluctuations, the GT-40 produces reliable results in any environment. These functions can be enhanced by fitting the collimator which assists improves measurement precision when preforming assays or measurements in a laboratory.
The SharpSeis Adaptive Deghosting module available in RadExPro utilize a stabilized approximate solution for the deghosting operator, applied to a seismic trace in both forward and reversed time. The resulting two traces (primary wavefield without the ghost, and ghost wavefield without the primary) are, then, combined in a non-linear manner in order to maximize the signal and suppress the noise trains, stabilizing the result even further. The optimum ghost delay is estimated adaptively to the data within a sliding window, to ensure the best possible match. This results in sharp crystal-clear seismic images with high signal-to-noise ratio. Some examples are shown below.
Example SharpSeis deghosting on data collected using the P-Cable system and airgun source and deep-towed streamers. The streamers were towed at around 12 m to facilitate deghosting and reduce the noises. Data courtesy of University of Trømso.
In typical marine seismic acquisition, a streamer towed on a given depth records not only an up-going wavefield reflected from the subsurface, but also a down-going field reflected from the sea surface and known as ghost wavefield. Destructive interference of the up-going and the ghost wavefields creates a set of notch frequencies in the recorded spectrum.
The first notch always appears at zero frequency and acts as a high-pass filter suppressing low frequencies, with the slope of the filter dependant on the streamer tow depth. The greater is the tow depth, the more low frequencies are registered in the spectrum.
However, the frequencies of the second and further notches also depend on the streamer tow depth - the greater it is, the lower are the notch frequencies. Since useful bandwidth is commonly limited by the first and the second notch frequencies, towing the streamer deeper, though increases low frequencies, at the same time limits the higher frequencies making the band narrower and compromising the resolution.
synthetic frequency spectrums for data, recorded at different towing depths of the streamer. Blue line represents data spectrum for towing depth of 7.5 meters, green line – 15 meters. The greater streamer depth, the earlier notch frequencies occur, making more low frequencies available, but also limiting high frequencies.
Should the ghost wavefield be removed, this would have both boosted up the low frequencies and cured the notches at high frequencies, thus recovering the full broadband data. However, the problem is that the straightforward analytical deghosting solution is highly unstable and for this reason can hardly be explicitly implemented in any digital processing system.
A number of alternative approaches to acquiring broadband data have been developed instead, involving, along with the data processing, some specific equipment and acquisition techniques, such as dual sensor (combined hydrophone and geophone), over-under (two streamers towed at different depths), variable depth (one streamer is towed in a tilted position). All these approaches, though do produce good data, have one and the same big problem: they make data acquisition complicated and expensive. They also are not applicable to the old data - if one wants it broadband, the only solution is to acquire a new survey.
For further information please contact sales@geomatrix.co.uk.
