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Effect of assumptions on refraction interpretation

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Proceedings Papers

Paper presented at the 1985 SEG Annual Meeting, October 6–10, 1985
Paper Number: SEG-1985-0301
... modeling procedure was also developed using generalized linear inversion techniques (Wiggins, 1972; Jackson, 1972) so that earth models can be constructed to fit refraction traveltime measurements. Effect of refractor structure on refraction statics One common assumption in refraction statics calculation...
Proceedings Papers

Paper presented at the 2009 SEG Annual Meeting, October 25–30, 2009
Paper Number: SEG-2009-1345
... shows similar stratigraphy. These layers are significant for hydraulic conductivity profiles, but the water table has a much greater effect on seismic waves. At the BHRS the water table is approximately 4 m deep. In 1997 and 1998 18 wells were drilled to aid in collection of hydrologic, geophysical...
Proceedings Papers

Publisher: Society of Petroleum Engineers (SPE)
Paper presented at the SPE Annual Technical Conference and Exhibition, September 21–23, 2021
Paper Number: SPE-205987-MS
... fundamental effective mixing models, such as Clausisus-Mossotti / Lorentz-Lorentz, average T-Matrix approximation, and Maxwell-Garnett mixing formulas, for interpretation of relative dielectric permittivity for non-reservoir rock conductor-insulator composites ( Garnett 1904 ; Bruggeman 1935 ; Lord Rayleigh...
Proceedings Papers

Paper presented at the 2018 SEG International Exposition and Annual Meeting, October 14–19, 2018
Paper Number: SEG-2018-2997700
... refraction becomes a dominant arrival at the far offset. When this velocity reversal occurs, the effectiveness of conventional first-arrival traveltime tomography is limited. Nevertheless, the later refraction arrivals still contain substantial information about the weathering layer and the long-wavelength...
Proceedings Papers

Paper presented at the 1988 SEG Annual Meeting, October 30–November 3, 1988
Paper Number: SEG-1988-0783
.... Here a simple Backus filter was applied to deal with the low velocity layer multiples. CONCLUSIONS In this paper it was shown how to interpret weathering layer effects in high resolution seismic profiling. Two methods to calculate weathering layer thickness were suggested, giving simular results...
Proceedings Papers

Paper presented at the SPE Annual Technical Conference and Exhibition, October 5–8, 2003
Paper Number: SPE-84569-MS
... fields, Gulf of Mexico, Interpreter s Corner, The Leading Edge, April 2003. 3. Li, X-Y., Dai, H., Mueller, M.C., and Barkved, O.I.: Compensating for the effects of gas clouds on C-wave imaging: A case study from Valhall, The Leading Edge, September 2001. 4. MacLeod, M.K., Hanson, R.A., Bell, C.R...
Proceedings Papers

Paper presented at the 1984 SEG Annual Meeting, December 2–6, 1984
Paper Number: SEG-1984-0424
... two directions in order to separate dip and velocity effects. This is incorrect in that one-directional data are sufficient given the redundancy of normal CDP shooting regardless of whether split spreads are being used. Redun- dancy is the key requirement, not direction. The use of refraction statics...
Proceedings Papers

Paper presented at the 1984 SEG Annual Meeting, December 2–6, 1984
Paper Number: SEG-1984-0422
... inversion. which best conforms to the noisy multiple layer data, with differing assumptions made about the overburden velocity V,(G). The shape of this model is due to the combined effect of structural and velocity transi- tions of the model shown in Figure 2, whose actual depth is a constant 800 ft...
Proceedings Papers

Paper presented at the 1985 SEG Annual Meeting, October 6–10, 1985
Paper Number: SEG-1985-0299
... generalized linear inversion techniques (Wiggins, 1972; Jackson, 1972) so that earth models can be constructed to fit refraction traveltime measurements. Effect of refractor structure on refraction statics One common assumption in refraction statics calculation is that the refractor is structurally smooth...
Proceedings Papers

Paper presented at the 1988 SEG Annual Meeting, October 30–November 3, 1988
Paper Number: SEG-1988-0574
... and refractor-depth components. All refraction techniques rely on assumptions to accomplish this step. When these as- sumptions are made explicit in the construction of a refraction model, their geological plausibility can be evaluated; the model may be easily perturbed to observe the effects of various refrac...
Proceedings Papers

Paper presented at the SPE Offshore Europe Conference & Exhibition, September 5–8, 2017
Paper Number: SPE-186148-MS
... running on high-performance computers (HPC) that allow exploration geophysicists and reservoir engineers to unlock, leverage tomorrow's reserves and mitigate subsurface uncertainties in a cost-effective way. The objective is on the one hand to exploit the complete seismic recordings for the benefit...
Proceedings Papers

Paper presented at the 1989 SEG Annual Meeting, October 29–November 2, 1989
Paper Number: SEG-1989-0882
... areas of study to demonstrate the effectiveness of refraction based structural solutions. The entire basin is subdivided into areas where specific solutions are required. A method for placing error bars on the validity of time structure is presented. INTRODUCTION Multiple geologic formations provide oil...
Proceedings Papers

Paper presented at the 2013 SEG Annual Meeting, September 22–27, 2013
Paper Number: SEG-2013-0131
... as corrections applied to compensate the effects of variations in elevation, weathering thickness, weathering velocity, or reference to a datum. A common, industry-standard method uses time picks from refractions (also called first breaks) with a model of the near surface to calculate statics. Cox (1999...
Proceedings Papers

Paper presented at the 2003 SEG Annual Meeting, October 26–31, 2003
Paper Number: SEG-2003-1235
... the upwelling effect seen in code B although it is not as pronounced. Code C does not show this effect, but this could be due to the lack of depth penetration. Evaluation of Refraction Tomography Codes Figure 5: From top to bottom: codes A, B, and C tomography results. Another model of interest...
Proceedings Papers

Paper presented at the 2011 SEG Annual Meeting, September 18–23, 2011
Paper Number: SEG-2011-4015
... assumption is valid, delay-time solution and GLI solution are very effective. A Simple Layer Model with Foothill Topography For a simple layer model, we add a variable topography extracted from the foothill model to examine the near- surface solutions with the same three traveltime methods. (a) True model (b...
Proceedings Papers

Paper presented at the 1988 SEG Annual Meeting, October 30–November 3, 1988
Paper Number: SEG-1988-1145
... interface is a plane of symmetry, both the critically refracted ray and thecorresponding slownessvector lieinthis plane, and we can describe the effects of the anisotropic half- space ntirely by the curve of intersection of the slowness surface with the refractor, the slowness curve F0.P) = 0 (1) (see fig...
Proceedings Papers

Paper presented at the SPWLA 57th Annual Logging Symposium, June 25–29, 2016
Paper Number: SPWLA-2016-W
... MHz) permittivity of a mixture based on its constituents is the CRIM or Complex Refractive Index Model (Birchak et al., 1974; Seleznev et al., 2011; Wharton et al., 1980). The CRIM equation is based on scattering theory and calculates the effective rock dielectric permittivity ( eff) following...
Proceedings Papers

Paper presented at the 1986 SEG Annual Meeting, November 2–6, 1986
Paper Number: SEG-1986-0597
... as a static correction. This plot is useful in detecting cycle- skips in the picks and in understanding dispersion effects present on the refracted arrivals. Time-distance plot and its uses The most commonly used plot in refraction work continues to be the time-distance plot or f-n plot. These plots show time...
Proceedings Papers

Paper presented at the 2017 SEG International Exposition and Annual Meeting, September 24–29, 2017
Paper Number: SEG-2017-17727844
... at intermediate and large offsets are usually refracted and guided events. Reflections and diffractions at in- termediate and large offsets are late arrivals. Their contribu- tion is less important in marine CSEM compared to refracted and guided events. This effect is exposed by analyzing the marine CSEM...
Proceedings Papers

Paper presented at the 1997 SEG Annual Meeting, November 2–7, 1997
Paper Number: SEG-1997-1059
..., Paradigm Geophysical Summary 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...

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