| Popis: |
Summary In Saudi Arabia, the complex three-dimensional nearsurface overburden can introduce large magnitude shortwavelength time delays greater than half a period and wavelengths greater than half an effective spread length. Since automatic residual statics algorithms fail to resolve these statics, additional geologic information is needed during the interpretation phase to constrain the near-surface model. These errors are overcome by combining this interpretation phase with a new partial-offset stack domain within a stand-alone PC-based interpretation system. This interpretation system uses multiple forward and reverse partial-offset stack displays in the common-receiver point (CRP), common-source point (CSP), and commonmidpoint (CMP) domains to delineate and estimate surfaceconsistent source and receiver statics. However, it is only possible to decouple the source and receiver statics when the offset distance is greater than the anomaly width (i.e., under shoot). This limitation is overcome by using a new 2D or 3D spatially fixed stacking pattern to organize CRP and CSP offset-dependent stacks for spatially fixed sources and receivers, respectively. These patterns are designed to “illuminate” the near-surface anomaly from different directions, discriminate between structural and surfaceconsistent velocity variations, and decouple shot and receiver statics. Each offset trace within a range of receivers or sources from a fixed set of binned sources or receivers will have the same constant surface-consistent static. This constant static term can be easily estimated and removed from the time picks when two patterns are overlapped. Hence, the surface-consistent source and receiver static components are decoupled. This is the only known efficient method for resolving surface consistent short-wavelength large magnitude and medium- to longwavelength statics in three-dimensions. |
