Description

Marine High–Resolution Seismic Data Processing

RadExPro is fully capable for both single–channel and multi–channel HR/UHR marine seismic data processing, either 2D or 3D. It is compatible with any type of marine sources: airgun, sparker, boomer, etc.

Advanced denoising, high–resolution offshore statics, designature (automatic wavelet estimation, deghosting, debubbling, deconvolutions), efficient demultiple algorythms for multi–channel (SRME) and even single–channel data (Zero–Offset Demultiple), 3D regularization, pre–stack and post–stack migrations—all these algorithms are available in RadExPro and are capable of improving the quality of the processing result significantly.

An experienced processor would particularly enjoy the outstanding flexibility of the software allowing even the most sophisticated processing scenarios to be easily implemented in the modern user–friendly interface—for only a fraction of the price of any big seismic processing system on the market.

Outstanding Results of Marine High–Resolution Seismic Data Processing in RadExPro

Ultra–high resolution (up to 3000 Hz) data, acquired with a sparker source, water depth 2–5 meters.
CDP interval is 1 m.
Processing was carried in RadExPro seismic software by GeoSurveys.

Processing of small volume (40 in3) airgun seismic data, acquired in the Barent Sea.
Data courtesy of Tromsø University.

3D regularization is dedicated for interpolating 3D seismic data by common offsets on the regular grid. Algorithm is based on wavefield reconstruction in F–Kx–Ky domain.

Inline before and after regularization

Time slice before and after regularization

Data courtesy of DONG Energy, prestack processing in RadExPro by GeoSurveys

Real–Time Marine Seismic Acquisition QC

What is marine real–time QC and why do I need it?

Real–time QC is dedicated for onboard seismic source and data quality control as soon as the data is received during marine seismic acquisition. It is aimed to identify any problems with seismic acquisition at the very same moment when they happen. This allows seismic crew to immediately fix the problems, minimizing related loss of operational time and money. Nowadays RT QC is the industry standard for marine seismic operations.

Typical real–time QC products are:

Source control products: near–field hydrophone signature, bubble peak amplitude, bubble peak time, bubble time period, source towing depth, flip–flop source energy identity.

Data control products: shot gathers, near–trace gathers, SOR/EOR/TARGET RMS amplitudes, signal/noise amplitudes, signal–to–noise ratio, real–time 2D stacks, frequency analysis.

This set of products controls most of the things happening on board, related to the seismic acquisition. By monitoring them, QC personnel and/or observers can easily identify “out of spec” issues like bad shots, bad or week channels, source air leakages, misfires, flip–flop source identity loss, low signal–to–noise ratio, strong noises, etc. Many of these issues requires immediate action and reporting.

The software connects to the data storage and input a shot record as soon as it is written. Each shot is read only once, to avoid network overload. After a shot is loaded into RAM of the local PC, it is input to the pre–defined QC flows that all run in parallel locally. All real–time displays run and update locally as well, without slowing down the network or using any processing time of your server nodes.

This, along with the optimized processing algorithms, allows QC of the data from thousands of channels in true real–time, using just an average good modern PC with a multi–core CPU and 46–bit Windows OS. Compare this to some other known packages, which are supposed to run procedures in the real–time, while on practice have dozens of shots delayed even working on a Linux cluster…

How it looks like?

Some examples of QC products are below:

Shot gather display

Standard fully customizable shot gather display.

A user–defined number of shots can be stored in memory and reviewed during acquisition.

Spectrum comparison for a number of shots

Several noisy shots can be seen at the start of the profile.

Near–trace gather display

NFH signature display

Near–field hydrophone and its bubble time period graph are displayed.

RMS amplitude map

Horizontal scale is shot number, vertical—channel number. Notice purple stripes on the image. The horizontal one indicates that channel 55 is dead, the vertical one—that shot number 1360 was bad. Purple areas around channels 200–240 indicate week channels due to weather conditions. Just one amplitude map can tell us a lot about what is happening onboard!

How do I export results?

All QC images are saved to pre–defined folders automatically after each line and stored in structured order, from where can be easily imported to an EOL report.

Furthermore, all QC results can be saved into a database, to be later played back or exported into SEG–Y files.

How it looks like?

Some examples of QC products are below:

Shot gather display

Standard fully customizable shot gather display.

A user–defined number of shots can be stored in memory and reviewed during acquisition.

Spectrum comparison for a number of shots

Several noisy shots can be seen at the start of the profile.

Near–trace gather display

NFH signature display

Near–field hydrophone and its bubble time period graph are displayed.

RMS amplitude map

How do I export results?

All QC images are saved to pre–defined folders automatically after each line and stored in structured order, from where can be easily imported to an EOL report.

Furthermore, all QC results can be saved into a database, to be later played back or exported into SEG–Y files.

SharpSeis Deghosting/Broadband Processing

In typical marine seismic acquisition, a streamer towed on a given depth records not only an upgoing wavefield reflected from the subsurface, but also a downgoing field reflected from the sea surface and known as ghost wavefield. Destructive interference of the upgoing and the ghost wavefields creates a set of notch frequencies in the recorded spectrum, which results in limiting frequency band and decreasing resolution.

Algorithm specifications:

Applicable for conventional marine seismic acquisitions—does not require specific acquisition solutions
Efficient for different types of sources (airgun, sparker, boomer…)
Applicable for both 2D and 3D data
The algorithm is adaptive—can handle changing ghost time delays both in time and distance

The algorithm was presented at EAGE Near Surface Geoscience 2014—First Applied Shallow Marine Geophysics Conference byVakulenko et al (2014).

SharpSeis Deghosting helps one to recover a broader frequency spectrum, resulting in improved seismic resolution and image clarity.

Examples of SharpSeis Deghosting Application

Norvegian Sea, marine seismic data, acquired with a P–Cable system with an airgun source and 12 8–channel streamers towed at around 2.5 m.
The data is courtesy of P–Cable 3D AS company.

Amplitude spectrums before and after broadband processing

University of Trømso P–Cable acquisition, data acquired with an airgun source and deep–towed streamers.
The streamers were towed at around 12 m to facilitate deghosting and reduce the noises.

Raw data / Data, after SharpSeis deghosting application

Deghosting of 2D conventional marine seismic data, acquired in the bay of Naples.

Raw data / Data, after SharpSeis deghosting application

Data courtesy Istituto per l’Ambiente Marino Costiero—CNR, Naples, Italy

2D/3D Seismic QC and In–Field Processing

RadExPro is capable for off–line seismic QC and in–field processing, either on–land or offshore:

Quick input of data of any size
Geometry assignment from SPS and P1–90 files
Geometry QC using predicted times of direct wave arrival, as well as survey maps

Visual control of seismic data and spectrums

Calculation of various seismic QC attributes for shot gathers and receiver gathers
Calculation of combined attributes, their display and analysis on linked cross–plots and histograms

Building of fold, offset/azimuth distribution and coverage maps

Complete set of algorithms for efficient in–field processing to produce a brute stack

Automatic 3D horizon picking

Near–Surface Data Processing

RadExPro provides a complete processing solution for all conventional near–surface seismic methods in one comprehensive package:

RadExPro is perfectly capable for in–depth processing of on–land near–surface reflection data.

Intuitive geometry assignment tool for most standard linear 2D acquisition scenarios

Loading geometry from ASCII tables and SPS–files for more complicated cases
Crooked–line 2D CMP binning

Both impulsive and vibroseis data processing
Near–surface 3D seismic data processing
Multicomponent data processing
Exhaustive set of signal processing algorithms and 2D filters
Interactive velocity analysis
Pre–stack and post–stack Kirchhoff migration

RadExPro includes Plus–Minus and GRM methods for seismic refraction.

First–break picking is made semi–automatically for all shot points at once, in one window.

In the automatic mode of Plus–Minus method, refracting boundaries are built in one click—the only thing required is prior assignment of time–curve segments to layers. In the manual mode, an experienced geophysicist can control the whole process and make some fine–tuning at any stage: building composite travel time curves, leveling of reciprocal times, computing velocity analysis and time–depth functions, and, finally, building the refraction boundaries.

In cases that are more complicated, use of GRM instead of Plus–Minus allows simultaneous reconstruction of both geometry of refracting boundaries and lateral changes of velocities along them more accurately.

A dedicated module for Multichannel Analysis of Surface Wave (MASW) available in the RadExPro for easy and competent evaluation of S–wave velocities of the subsurface.

Input from SEG–2, SEG–D, SEG–Y…
Intuitive geometry assignment
FV and FK dispersion images calculated independently—you get the best of both
2–3 clicks to extract a dispersion curve accurately—with semi–automatic smart picking algorithm
1 click to save all dispersion curves at once and send them to inversion
Joint inversion of fundamental and higher modes, unlimited number of modes allowed
Exceptionally user–friendly design—you will enjoy it!

FV and FK dispersion images with dispersion curves picked: accurate, easy and very fast!

You can invert all extracted modes jointly or indicate a particular combination of modes for the inversion. For instance, you can, first, invert the fundamental mode only (which is more stable) and then use the result as the initial model for joint inversion with the higher modes.

You can invert all dispersion curves from all receiver mid–stations in one click, or thoroughly control inversion process at each location. You can also make a thoroughly controlled inversion at one location and then use the result as an initial model for automatic inversion at all other locations along the line.

Resulting Vs section can be printed or exported to ASCII (together with Vs30) or GRD files.

Travel–Time Tomography module in RadExPro provides an intuitive interactive tool for recovering of 2D velocity model from the first–arrival travel–time curves.

You can use Herglotz–Wiechert inversion for automatic generation of the initial model or define it using interactive layers and boreholes. Of course, you can also edit the model grid manually.

The tomography algorithm used is based on the known Occam inversion, however with some important modification. Beside velocity, each cell of the grid has confidence parameter that takes values from 0 to 1. Use this parameter to specify how confident you are in any particular part of the initial model. For instance, near the borehole you are pretty sure about velocities—why not to tell the software explicitly that you don’t want the algorithm to change them too much?

Something went wrong while tomography is calculated and you are unhappy with the ongoing values? You can pause the calculation at any iteration, change any parameters (and even the current model!) and continue. You can also scroll back through the iterations, use the result of any of them as a new initial model and start the whole process again with modified parameters.