Multiple Attenuation
Arcis offers a full suite of multiple attenuation techniques:
Free Surface Related Multiple Attenuation
SRME - Surface Related Multiple Elimination
(Delphi Consortium Sponsor)
SRME is a method for removing all free surface multiple energy. It is a data driven approach which operates in the prestack domain and attempts to predict and subtract the multiples.
RADON – High resolution (parabolic & linear) Radon transform demultiple
RADON has options to perform either linear or parabolic Radon transforms. After transforming, free surface multiple energy can either be directly removed in the transform domain or estimated in the transform domain then removed back in the input domain. The program can perform a normal least squares Radon transform or a high resolution Radon transform.
ICone™ - Intelligent Coherent Noise Elimination
ICone™ is a trajectory-scan technique that identifies parabolic or linear events in the time-space domain and subtracts them from the input data. The algorithm, which was originally conceived for the attenuation of linear noise trains typically encountered in land data, has both 2D and 3D implementations and has been successfully adapted to eliminate free-surface-to-water-bottom multiple energy. An interactive graphical tool facilitates optimal parameter selection and testing. Click here for ICone™ interactive demo. In our water-bottom-multiple adaptation, we employ the following flow:
Step 1 – CMP domain water velocity NMO
Step 2 – Water bottom multiples become quasi-horizontal (locally coherent), and are treated as linear noise. These are identified over space-time windows and are measured in terms of semblance coherency.
Step 3 – Maximum semblance coherency to identify dominant dip directon of multiple energy
Step 4 – Adaptive modeling and subtraction
Step 5 – NMO removal
Raw input stack
Stack after SRME
Stack after 3D ICone™
Click here to see difference plot of input minus 3D ICone™
Internal Multiple Attenuation
RADON – High resolution (parabolic & linear) Radon transform demultiple
RADON, our high resolution Radon demultiple tool, may be used to attenuate internal multiples as well as those related to the water bottom and free surface. Because subtle velocity discrimination lies at the heart of the Radon-based internal multiple approach, we have augmented the basic algorithmic kernel with a graphical interface to allow easy specification of time and space variant Radon filter masks.
Click below to view a demo of our interactive Radon tool.
Input CMP gather (left pane) and interactive Radon filter picking interface (right pane)
CMP gather after multiple elimination using the Radon filter picked using the interactive tool
ICone™ - Intelligent Coherent Noise Elimination
ICone™ , our trajectory-scan algorithm which was originally conceived for linear noise rejection on land data and which has been successfully adapted to the water bottom multiple problem, may also be used for internal multiple elimination. The internal multiple implementation of ICone™ essentially seeks to remove energy which exhibits coherence along parabolic trajectories. Of particular interest is the fact that it can overcome the well-known ‘constant amplitude along parabolae’ limitation associated with Radon-based demultiple techniques. ICone™ ’s ability to tolerate amplitude variation with offset stems from the fact that the multiple identification kernel operates in small spatio-temporal windows and thereby provides spatial localization across the offset dimension. Data results to-date are very encouraging; moreover, we are hopeful that the technique will serve as a launching pad for new-generation local Radon demultiple approaches.
