Geosciences

SEG's energized explorers

This year’s Society of Exploration Geophysicists convention enjoyed an energy that it hasn’t had in recent years. Over 6,500 geophysicists from around the world gathered to share insights into the world of seismic, gravity, and magnetics.

The latest innovation is the combination of clustered, Linux-driven CPUs with off-the-shelf graphics processing unit (GPU) cards from the computer gaming world. This combination creates a fast visualization workstation that can handle larger data sets. Silicon Graphics displayed its new device that uses AMD’s Opteron processors coupled with ATI’s GPUs. Sun answered with a similar system based on Intel’s Itanium processors and nVidia’s GPUs.

The market for marine towed-seismic acquisition is tightening as the vessel fleet moves to higher utilization rates. The towed seismic market jumped with the letting of large contracts from ONGC, India’s national oil company.

Of note is the growing interest in nodal systems for deepwater seismic acquisition. This approach uses 4C instrument packages (three oriented geophones and a hydrophone) dropped into deepwater in a widely spaced pattern. The shooting vessel then creates a dense air gun source pattern above and around the seabed array. A signal from the vessel releases the node’s weighting element, returning it to the surface for collection, data retrieval, and redeployment.

Another nodal technology, CSEM (controlled source electro-magnetics), entered the market. This system uses a deeply towed, pulsed EM source to induce current in the seabed, which is measured by the antennas spaced on the seabed. The process detects hydrocarbon edges where a resistivity change occurs. Schlumberger has announced its purchase of AGO, which has gathered 40 CSEM surveys over the past year.

The next major market for seismic contractors is production seismic (4D) - the acoustic monitoring of producing fields. This market has been the province of towed-array contractors. However, limits on streamer positioning often make it difficult for seismic processors and interpreters to separate signal from noise in 4D difference volumes.

WesternGeco’s Q-marine system is gaining market traction for 4D surveys because of its ability to steer the streamer and match the surface locations of earlier surveys. Better positioning accuracy helps, but fixed-seabed sensor arrays solve this problem.

The growing market acceptance of 4D seismic has encouraged the makers of competing towed-streamer and seabed-placed sensor technologies. These manufacturers are bringing new options to the market with more durable ocean bottom cable systems in conventional geophone, accelerometer, and light-fiber technologies.

Affordable wave equation

CGG is offering its WaveVista wave equation migration process for the same economic conditions and turnaround as the Kirchhoff method. The process addresses complex wavefronts associated with high-velocity layers, like salt, and claims improved quality and resolution in less complex environments. The software produces full pre-stack angle gathers for amplitude analysis with angle, velocity model update, and post-migration processing.

TECHNOLOGY- Fault picking

Paradigm has introduced its new fault picking software, Automatic Fault Extraction. New interpretation efficiencies were presented by integrating Coherence Cube, 3D Propagator, Automatic Fault Outline, and Automatic Fault Extraction under the company’s epos3 system.

Sun grid

Sun Microsystems Inc. has released Sun utility computing for high-end grid, utility-priced services for grid computing. Building on its Sun N1 Grid Utility Computing Pay-For-Use Cycles, the new offering will make pay-for-use services available to customers with high performance, compute-intensive requirements for short- to mid-term needs, as well as for spikes in demand. The service will be delivered through Sun partners Atos, Origin, CGI, and EDS.

EXPLORATION - Fly low, gather hi-res

Fugro Airborne Surveys introduced its Georanger I at the SEG convention. The unmanned airborne vehicle (UAV) is a fixed wing, high-resolution aeromagnetic survey system resulting from a two-year research and development program for data acquisition offshore and in remote locations.

The UAV is capable of fully autonomous 3D flight, has an endurance of over 10 hours, and cruises at 75 km/hr. According to Jeffrey Rowe, marketing manager and senior geophysicist for Fugro, the UAV weighs 35 lb and uses 1.5 lb of fuel to gather 400 line-mi of data. The technology in the UAV has error-analysis capability and Iridium satellite communications, providing the operator with continuous system status, position, and velocity updates.

Marlim 4D

Petrobras has selected WesternGeco to acquire and process a 3D seismic survey over the Marlim complex, offshore Brazil. The Marlim complex, comprising the Marlim, Marlim East, and Marlim South fields, is the largest deepwater producer of oil and gas in the world.