簡介：西方奇科公司（WesternGeco ）的海洋地震數(shù)據(jù)采集已經(jīng)由理想變?yōu)楝F(xiàn)實。公司的連續(xù)射孔技術(shù)，需要不間斷的全角度海洋地震數(shù)據(jù)。
WesternGeco has taken an improved method for marine seismic data acquisition from concept to reality. The company’s coil shooting technique, which acquires full-azimuth (FAZ) marine seismic data continuously by traveling in a circular path, enables complex FAZ 3D surveys to be acquired with only a single acquisition vessel.
This technique reportedly advances geophysics by enhancing current multi- and wide-azimuth (MAZ and WAZ) techniques, proven methods of seismic acquisition for complex geological areas. These surveys typically involve taking several passes along the same path or using several vessels offset from each other?some towing sources, others towing sources and streamers. The result is better target illumination thanks to greater azimuthal coverage and higher signal-to-noise ratios.
It was during a project in the Gulf of Mexico (GOM), however, that WesternGeco recognized that high-quality FAZ recordings could be achieved by acquiring data with a single vessel traveling in a circle, thereby removing the need for shooting a survey several times using one vessel?as with MAZ?or employing several source and recording streamer vessels, which is required by current WAZ designs.
In the coil shooting technique, a single vessel sails in overlapping circles, creating a large number of shot/receiver positions. Additionally, a single source/receiver vessel can produce unprecedented offset and azimuth sampling, leading to higher-quality images with superior noise suppression, according to WesternGeco.
The concept of coil shooting has been postulated for some time, but WesternGeco states that it is now enabled thanks to the inclusion of the company’s Q-Marine technology?a family of products and services consisting of calibrated sources, positioning and single-sensor systems, as well as steerable streamers?that improve seismic data quality and reliability.
For example, the coil shooting technique incorporates Q-Marine’s Q-Fin steering devices to control the depth and lateral position of streamers, calibrated single sensors to provide superior noise attenuation, and a fully braced acoustic positioning network that produces accurate positioning information of all in-sea equipment. These combined technologies make sailing in circles possible while also maintaining constant streamer separation and achieving accurate receiver positioning.
WesternGeco has field tested this acquisition technique in the GOM and the Black Sea, reportedly producing positively dramatic results that showed the potential for applying the technique on a global scale. Steering the vessel, streamers, and sources in a corkscrew fashion delivers a greater range of azimuths and offsets than parallel WAZ geometries, and there are no nonproductive intervals for line changes.
The company states that coil shooting’s efficiency and data delivery make it well suited for addressing challenges in imaging complex geologies, such as beneath salt and basalt structures.
The offshore E&P industry has taken notice of the innovation and potential positive impact of the coil shooting technique. WesternGeco was awarded a “Spotlight on New Technology Award” by organizers of the May 2009 Offshore Technology Conference in Houston. The technology and application of the technique successfully met the five criteria for a Spotlight Award: the technology should be new, innovative, proven, used in a broad range of applications, and have a significant impact on the industry.
To learn more, visit WesternGeco’s coil shooting website.
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