# Reservoir geophysics exercises

Series | Investigations in Geophysics |
---|---|

Author | Öz Yilmaz |

DOI | http://dx.doi.org/10.1190/1.9781560801580 |

ISBN | ISBN 978-1-56080-094-1 |

Store | SEG Online Store |

**Exercise 11-1.** Derive equation (**2a**) for the Fresnel zone using the geometry of Figure 11.1-3.

**Exercise 11-2.** Refer to Figure 11.4-1a. Consider a surface multiple from the first reflecting interface. Trace the traveltime on the VSP diagram in Figure 11.4-1b. Multiples do not reach the downgoing wave path; thus, they can be eliminated by corridor stacking.

**Exercise 11-3.** Refer to Figure 11.4-1b. Should the slopes of the downgoing and upcoming waves associated with a layer be the same in magnitude?

**Exercise 11-4.** What procedure does CMP stacking correspond to in the *f − k* domain?

**Exercise 11-5.** Sketch the traveltime response for a point scatterer on a zero-offset VSP record.

**Exercise 11-6.** Consider a CMP gather with a single reflection event. Suppose you have applied hyperbolic moveout correction using equation (**90**) and discovered that the event is not flat for all offsets. Instead, the moveout-corrected event may have one of the three shapes shown in Figure 11.E-1. Match each of the curves *A, B*, and *C* with the following three possibilities:

- You have applied hyperbolic moveout correction using an erroneously low velocity in equation (
**90**). - You have applied a second-order moveout correction (equation 3-4b) to an event that has a fourth-order moveout behavior described by equation (3-5a).
- You have ignored anisotropy in moveout correction described by equation (
**92**).

## Figures and equations

**Figure 11.4-1**Vertical seismic profiling geometry. (a) Raypaths and (b) associated traveltimes (see text for details). Static correction amounts to mapping traveltime associated with raypath*ABC*to traveltime associated with raypath*ABC*+*CD*; the NMO correction amounts to mapping traveltime associated with raypath*ABCD*to traveltime associated with raypath 2*DE*.

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## See also

- Introduction to reservoir geophysics
- Seismic resolution
- Analysis of amplitude variation with offset
- Acoustic impedance estimation
- Vertical seismic profiling
- 4-D seismic method
- 4-C seismic method
- Seismic anisotropy
- Mathematical foundation of elastic wave propagation