Tidal effects on fault movements
Recent work is identifying a causal relationship between earthquakes and the extra-terrestrial forces of gravitation – the tidal cycle. The gravitational forces of the sun and moon act most strongly on the seas, moving great masses of water from one side of the earth to another. The land shifts as well, as the tidal forces pull the Earth upward. It is as if the Earth "breathes," expanding and contracting while the sun and planets spin and align in relation to the Earth.
When the Earth expands, faults can slip. The added water pressure of the tides can increase movement on the continental slopes and add a cyclic differential pressure to keep salt moving upward.
According to Jan Cannon of Planetary Data, the 1906 San Francisco, California, earthquake, the 1989 Oakland, California, earthquake, and the 1964 Alaska earthquake near Anchorage were all in high tide windows.
Another high tide window is coming Dec. 31, 2002, through Jan. 5, 2003, as the Earth reaches perihelion (its closest approach to the sun). It is likely that a significant series of quakes will occur around this time.
The restructuring of the seismic industry has just begun. WesternGeco is closing its land seismic operations in the lower 48 US states and Canada due to sustained unprofitable market conditions. About 1,200 employees will be affected worldwide. Land operations will continue in Alaska, Mexico, and other economically viable areas worldwide. Offshore consolidation will likely take place as well at some future time, but the company has made no mention of plans for its vessels.
The restructuring will de-emphasize conventional seismic operations, which have been severely affected by commodity pricing, excess risk, and difficult terms over the last 10 years. The company is accelerating its move toward the production side of the business and will provide seismic-based reservoir information to aid asset teams.
"The action we've taken is an inevitable result of the high-risk, no-return state of affairs in the seismic industry," said WesternGeco President Gary Jones. "We will focus on customers and geographical areas where the value we provide is recognized and will concentrate our growth in providing advanced reservoir information technology. This move is another step in our long-term commitment to sound business practices, including shutting down losing operations and exiting markets where reasonable terms and conditions do not prevail. However, given fair compensation and acceptable terms, our services are available everywhere to everyone."
Veritas Marine Surveys has begun acquisition on a non-exclusive 3D survey located in the Alaminos Canyon area of the Gulf of Mexico. Alami-nos Canyon Phases II and III will cover 6,500 sq km (280 US Minerals Management Service OCS blocks) of the Perdido Fold Belt with long offset high-resolution 3D data. Eight 8,100-m stream-ers will be towed and recor-ded into 25-m crossline bins. Acquisition will be complete early summer 2003.
South African survey
Jebco Seismic, the Petroleum Agency of South Africa, and Global Exploration Services have identified a new petroleum system off the east coast of South Africa. Initial work has already proved the presence of wet gas and oil with Upper Jurassic marine source rock affinities.
Jebco plans to acquire 6,500 km of 2D seismic over the Tugela Cone. This is a large prograding submarine deltaic system, extending 200 km into the Indian Ocean. The survey includes the northernmost part of block 16 and former blocks 17 and 18.
The Veritas Vantage began a 6,500 sq km 3D survey in the Alaminos Canyon area of the deepwater Gulf of Mexico.
This part of South Africa's offshore will remain closed to exploration until the data is made available. The Petroleum Agency will then accept industry proposals to license acreage.
CGG recently added 1,536 CPUs in the Houston facility, bringing its worldwide data processing capability past the 10,000-CPU mark. CGG's worldwide network of seismic centers offers an overall computer capacity of over 15 Teraflops (15 million million floating point operations per second).
All CGG processing centers have their own computing power and can draw additional capacity from any of the three regional "hubs" in Houston (7 Teraflops), London (7 Teraflops), and Kuala Lumpur (1 Teraflop). The London facility has 1,088 CPUs, while the Kuala Lumpur facility has 20 CPUs. This increase in computing power supports CGG's anisotropic Kirchhoff pre-stack time and depth migration and its shot-domain wave-equation migration services.
RockWare released RockWorks 2002, an extensive PC-based software for creating boring logs, cross sections, fence diagrams, solid models, contour maps, and more. A key feature in the new version allows the user to export 3D fence diagrams as shape files with z values for use in ArcGIS 3D Analyst. Other features include OpenGL 3D Graphics, a new data management system, a new borehole manager, and many other tools. RockWorks 2002 runs in Windows98/NT/2000/XP and is available with both single-user and network licenses.