Practical Application of CFP Technology to Resolve Complex Near Surface Problems and to Estimate a Velocity-depth Model

摘要

Complex topography and highly variable weathering layers in the near surface can severely degrade the quality of seismic data and result in a distorted structural image of the subsurface reflectors. One objective of this work is to compare seismic image quality after application of Common Focus Point (CFP) redatuming with images generated using more conventional statics techniques. The CFP process is independent of any velocity model and derives data-driven focusing operators. CFP operators inherit the kinematic phenomena of the wavefield that passes through the near surface. These operators are estimated using parametric inversion. Using these operators, a complete wavefield redatuming can be performed moving the data recorded at the surface to a new datum underneath the complex near surface. A second objective of this work is to demonstrate that CFP operators can be used in a tomographic inversion process to obtain a fine-tuned velocity-depth model that is more geological in appearance and to determine the actual positions of the focusing points. The redatuming results showed significant improvements over results from traditional statics correction methods in terms of better continuity of the deeper reflection events as well as reliability of the structural time image.