Tying seismic to well data using structural uncertainties

Cognot, Richard; Thore, P.; Haas, A.

doi:10.1190/1.1932137

Cited by 4 publications

(2 citation statements)

References 2 publications

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“…In Figure 2, these image-wave rays are indicated by the arcs that join the three different migrated domelike images. As was recently recognized independently from geometrical considerations in Cognot et al (1995) and Liptow and Hubral (1995), and will be mathematically shown below, these image-wave rays are circles for the depth migration ( Figure 2a) and parabolas for the time migration (Figure 2b). …”

Section: Kinematic Migrationmentioning

confidence: 97%

Seismic constant‐velocity remigration

et al. 1997

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When a seismic common midpoint (CMP) stack or zero-offset (ZO) section is depth or time migrated with different (constant) migration velocities, different reflector images of the subsurface are obtained. If the migration velocity is changed continuously, the (kinematically) migrated image of a single point on the reflector, constructed for one particular seismic ZO reflection signal, moves along a circle at depth, which we call the Thales circle. It degenerates to a vertical line for a nondipping event. For all other dips, the dislocation as a function of migration velocity depends on the reflector dip. In particular for reflectors with dips larger than 45°, the reflection point moves upward for increasing velocity. The corresponding curves in a time-migrated section are

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Section: Kinematic Migrationmentioning

confidence: 97%

Seismic constant‐velocity remigration

et al. 1997

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“…Lecour et al 2001, Mallet 2002) but other choices have been proposed (e.g. Cognot et al 1994). • Next, for each stochastic realization, the magnitude of the displacement is considered as a random property modeled thanks to a classical geostatistical method.…”

Section: Introductionmentioning

confidence: 99%

Solid Earth Modeling and Geometric Uncertainties

Mallet

Tertois

2010

All Days

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In computer geoscience, reservoir studies aim at estimating hydrocarbons in place to determine prospect viability and define development strategies. Assessing uncertainty on reservoir geometry is even more important than assessing uncertainty on rock properties because the property model depends on reservoir geometry. The authors propose a methodology for assessing geometric uncertainties on a unified solid earth model and show its application to a subsurface model. A reference structural model is perturbed to reflect geometric uncertainty and several equiprobable realizations of the structural model are created. Instead of applying one global transformation as in most current methods, geometric uncertainties from different sources are assessed successively or jointly in each realization. The difficult problem of maintaining geological consistency while modifying structural models is addressed by using a structural model which is solid-based rather than surface-based: fault/fault and fault/horizon contacts are watertight by construction and constraints developed for this project ensure horizons do not intersect. The structural model is linked to the property model by a three-dimensional transformation, which enables perturbing the structural model independently from the property model instead of applying geometric transformations to the property model or having to recreate a property model for each geometric realization.

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Time-migration velocity analysis by image-wave propagation of common-image gathers

2008

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Image-wave propagation or velocity continuation describes the variation of the migrated position of a seismic event as a function of migration velocity. Image-wave propagation in the common-image gather (CIG) domain can be combined with residual-moveout analysis for iterative migration velocity analysis (MVA). Velocity continuation of CIGs leads to a detection of those velocities in which events flatten. Although image-wave continuation is based on the assumption of a constant migration velocity, the procedure can be applied in inhomogeneous media. For this purpose, CIGs obtained by migration with an inhomogeneous macrovelocity model are continued starting from a constant reference velocity. The interpretation of continued CIGs, as if they were obtained from residual migrations, leads to a correction formula that translates residual flattening velocities into absolute time-migration velocities. In this way, the migration velocity model can be improved iteratively until a satisfactory result is reached. With a numerical example, we found that MVA with iterative image continuation applied exclusively to selected CIGs can construct a reasonable migration velocity model from scratch, without the need to build an initial model from a previous conventional normal-moveout/dip-moveout velocity analysis.

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Tying seismic to well data using structural uncertainties

Cited by 4 publications

References 2 publications

Seismic constant‐velocity remigration

Seismic constant‐velocity remigration

Solid Earth Modeling and Geometric Uncertainties

Time-migration velocity analysis by image-wave propagation of common-image gathers

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