Estimation of long-wavelength near-surface velocity and low-relief structural anomalies Part I. A case history in central Saudi Arabia

Peter I. Pecholcs, Sun Nguyen, Dan Kosloff, Alex Litvin

Research output: Contribution to conferencePaperpeer-review

Abstract

Undetected near-surface and subsurface velocity variations greater than an effective spread length produce false structures both in time and depth. The estimation of these variations rely on uphole measurements, high density shallow reflection data and sufficiently long offsets for subsurface reflectors. Despite inadequate near-surface velocity-depth measurements in the study area, we developed a strategy for the detection and estimation of both near-surface and subsurface long-wavelength velocity and low-relief structural variations. We chose two 2D seismic lines (dip and strike) over two existing low-relief fields in central Saudi Arabia, to demonstrate how the velocity-depth ambiguity problem is partially overcome by integrating the refraction delay time solutions derived from multiple refractors below the seismic reference datum with iterative pre-stack depth migration, residual analysis, and reflection tomography. We compare these results with the conventional isopach depthing method and discuss how this strategy improves the structural integrity of potential prospects. Even with the verification of the near-surface velocity and structural anomalies along the dip line and buried velocity anomaly along the strike line through forward modeling and flatness of depth image gathers, these models are non-unique. Based upon this case study, a new constrained tomographic algorithm has been developed which overcomes the above ambiguity and is discussed in Part II.

Original languageEnglish
Pages1059-1062
Number of pages4
DOIs
StatePublished - 1997
Externally publishedYes
Event1997 Society of Exploration Geophysicists Annual Meeting, SEG 1997 - Dallas, United States
Duration: 2 Nov 19977 Nov 1997

Conference

Conference1997 Society of Exploration Geophysicists Annual Meeting, SEG 1997
Country/TerritoryUnited States
CityDallas
Period2/11/977/11/97

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