Robert J. Garotta is considered to be one of the fathers of multicomponent seismic acquisition. He graduated from the Faculté des Sciences in Paris and began his career in the geophysical department of the French National Center for Scientific Research (CNRS), where he conducted work in the magnetotelluric method. He spent 37 years at CGG, first in the gravity method, then as a seismologist in field operations. Later he joined the General Geophysics Division as an area geophysicist in charge of quality control and technical assistance to operations. His solid technical background, combined with his permanent involvement in field operations, gave him the experience to successfully address the most complex geophysical problems. He concluded his career at CGG as senior vice president of geophysical methods. He is now advising the CGG group in the area of multicomponent seismic data from acquisition to interpretation. He has made significant contributions in various fields of research and development such as vibroseis, velocity analysis, static corrections and 3-D survey design, and is the author of numerous technical papers. He was one of the key promoters of shear wave acquisition, processing and interpretation in our industry. His pioneering work on the use of converted shear waves led him from the first experiments in France to active participation in the Colorado School of Mines projects. A longstanding member of the SEG and of the European Association of Geoscientists & Engineers (EAGE), he was the co-recipient of the Conrad Schlumberger award in 1965. Garotta was awarded SEG Honorary Membership in 2001 for his many accomplishments.
2000 SEG/EAGE Distinguished Instructor Short Course
Shear Waves from Acquisition to Interpretation
Multicomponent studies are perhaps today at the same stage that 3-D studies were fifteen years ago. The renewed interest in shear waves is obvious, especially in the subsea environment where millions of dollars are being spent on acquiring the elastic response of the earth. Because shear wave-related techniques are raising the interest of the E&P industry, this course addresses, through case histories, the practical aspects of multicomponent data acquisition, processing and interpretation.
Although the industry resorts to shear wave propagation when the usual compressional response is poor, the main promise of the shear wave response is in its combination with the compressional one. However, this is possible only when the quality and resolution of the two responses are similar.
The first part of the course is devoted to overcoming the difficulties associated with shear wave acquisition. Converted mode operation is covered in detail using real-life examples. The particularities of sea bottom receivers are also examined.
The second part of the course reviews the processing and the main challenges of the shear converted modes: static corrections, gathering, velocity analysis and compensation for shear wave splitting in axial anisotropy. The course gives a detailed description of processing sequences. 2-D and 3-D results, yielding natural axis orientation of layers, are compared in shear and PS converted modes.
The third part of the course is devoted to case histories where new attributes, such as Vp/Vs ratio, crack density, or fracture orientation, are illustrated in a reservoir characterization context. These case histories can guide the geophysicist to decide if a particular geological situation can be best handled using shear waves.
The accompanying textbook is available for purchase.