# Dictionary:Double-square-root equation

The traveltime surface of a point diffractor in offset space where raypaths are straight and the source and receiver are not coincident; see Figure D-20b.

If *x*=midpoint location and *y*=offset (source-geophone distance), it is the surface *t*(*x*,*y*)

where *m*=inline distance from diffracting point to the midpoint and *h* its depth. The surface is called a Cheops pyramid (ke’ ops). This equation contrasts with the hyperbolic **single-square-root equation** for a zero-offset (CMP) section,

*DMO processing* transforms a Cheops pyramid so that a cylindrical hyperbola (see Figure D-20d) is obtained after normal moveout correction with the correct velocity. After a transformation *y*=*Ut* that constitutes slicing the pyramid by radial planes containing the *x*-axis, NMO can be applied correctly.

## References

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## External links

- ↑ Levin, F. K., 1971, Apparent velocity from dipping interface reflections: Geophysics, 36: 510–516.
- ↑ Deregowski, S. M., 1986, What is DMO: First Break, 4, No. 7, 7–24.
- ↑ Whaley, J., 2017, Oil in the Heart of South America, https://www.geoexpro.com/articles/2017/10/oil-in-the-heart-of-south-america], accessed November 15, 2021.
- ↑ Wiens, F., 1995, Phanerozoic Tectonics and Sedimentation of The Chaco Basin, Paraguay. Its Hydrocarbon Potential: Geoconsultores, 2-27, accessed November 15, 2021; https://www.researchgate.net/publication/281348744_Phanerozoic_tectonics_and_sedimentation_in_the_Chaco_Basin_of_Paraguay_with_comments_on_hydrocarbon_potential
- ↑ Alfredo, Carlos, and Clebsch Kuhn. “The Geological Evolution of the Paraguayan Chaco.” TTU DSpace Home. Texas Tech University, August 1, 1991. https://ttu-ir.tdl.org/handle/2346/9214?show=full.