CGG Borehole Services completed acquisition of a large vertical seismic profile (VSP) survey for Romania's Petrom S.A. in the Black Sea. The survey consisted of 161 parallel lines at 50-meter spacing with two diagonal lines crossing the grid from corner to corner. Each diagonal was 11.3 km in length. This configuration yielded a total of 26,695 source positions and 320,340 shot-receiver pairs. The survey was gathered using CGG's SST-500 12 by three component VSP receiver array.
P to S wave conversion providing better images
Schlumberger Geco-Prakla announced the licensing of its first non-exclusive TQ3D-4C survey in the North Sea. BP Amoco, as operator, licensed the survey over Lomond Field in block 23/21 of the UK Central Graben. The geophone/hydrophone arrays were placed on the seabed to collect both pressure (P) and shear (S) wave data.
"The converted wave (P-wave to S-wave) data give significantly better imaging below the Lomond gas chimney than the original P-wave data, which should enable the Lomond group to place future wells with greater accuracy and reduce risk," stated David Pope, BP Amoco geophysicist. The survey is 36 sq km in area and was collected by the M/V Polar Queen and M/V Akademik Shatskiy.
Veritas opens Stavanger processing center
Veritas DGC Inc opened its newest processing center in Stavanger, Norway. The addition of this facility brings the number of Veritas processing centers worldwide to 22. The new center is tightly integrated to the company's NEC SX-4 supercomputers in Crawley, UK; Houston, USA; and Singapore. The Stavanger location is part of the firm's strategy to provide services by putting satellite centers close to client offices, and providing access to regional supercomputer hubs, explained Gareth Williams, Marketing Manager of Data Processing in Europe, Africa and the Middle East (EAME). Stavanger is the third satellite center to be opened by Veritas in the EAME region. The others are located in Aberdeen, Scotland and Abu Dhabi, UAE.
Determining imaging potential early
Schlumberger Geco-Prakla has begun work on a 1,100 sq km non-exclusive 3D survey, which will include regional evaluation of depth imaging (REDI). The survey will cover 45 blocks in Alaminos Canyon, in the western Gulf of Mexico. REDI includes representative 3D depth migrated data and a regional pore pressure prediction volume based on 3D common image point tomographic velocity analysis. It is designed to establish imaging potential for pre-stack depth migration projects early in lease block evaluation. First availability will be fourth quarter 1999.
Hydrates search
China's Xinhua news agency reports that China has decided to search for natural gas hydrates in its seabed. The China Ocean Mineral Resources recently completed studies on the exploration and prospecting technology for the new energy source. Reserves are estimated at 1.1 trillion tons.
Workflow integration
Geographix (Halliburton/Landmark) an nounced its latest version, Geographix Release 99.2trademark. This new release creates a workflow solution to integrate seismic and geologic interpretation. The version has been extensively tested for Y2K readiness, based on industry standards. The new software integrates Landmark's SeisVision™, SeisWorks™, and Earthcube™ for WindowsNT®-based computer systems. (website:www.geographix.com).
Chemical mass balance through subduction
The Ocean Drilling Program (ODP) completed Leg 185 to the Mariana and Izu-Bonin trenches off Japan. The goal of this most recent effort was to gather samples to understand the mass balance of chemicals cycled through the subduction/vulcanism process. While much is known, researchers hope to gain a better understanding of the aging process of the uppermost layer of the solid earth, the flow of materials through the zone between deep sea trenches and volcanic arc, and the fluid circulation at active margins.
The Mariana and Izu-Bonin arcs were both created by the same subducting plate, yet have distinct geochemical signatures. Two sites were drilled to depths of 900 meters below the seafloor in 6,000-meter water depths. This stretched the JOIDES Resolution to its maximum capacity, breaking a record for deepwater drilling. The vessel has departed Japan for its next voyage, Leg 186. The goal of this journey is to install long-term, deep seabed observatories for the study of earthquakes and measuring properties of the Earth's mantle.
Icelandic plume
Seismologists at the Utrecht University in The Netherlands have imaged a deep mantle plume under Iceland. Harman Bijwaard and Wim Spakman calculated 7.6 million seismic wave paths to produce an image showing a 350-km wide plume of molten rock reaching upward to the Icelandic surface from the mantle 400 km below. The report appears in Earth and Planetary Science Letters.
Orbital climate controls
A 413,000-yr cycle in the Earth's orbital elongation has been identified by Jose Rial, Geophysicist, of the University of North Carolina. This longer-wave cycle appears to control the timing of ice ages, which vary from 100,000 years to 120,000 years apart. This discovery illustrates the overwhelming effect that long-cycle processes can have on global climate.
As reported in Science, the longer cycle modulates the ~100,000-yr glacial cycle, similar to frequency modulation of FM radio broadcasts. Shorter cycles of 23,000 years and 41,000 years also exist, which fit with the Earth's routine wobbling (see related article in Offshore's August 1999 issue). No physical mechanism has been identified yet to account for the long-wave cycle. Earth's climate is the result of many cyclic interactions, both long and short. One short-term event or process should not significantly alter climate.
