Favorite 3-D Designs
One of the favorite games that has withstood the test of time and computer technology is chess. Rarely are two chess games exactly the same. One of the reasons is that each piece has its own unique set of rules for movement. Some can move only diagonally, some only orthogonally, and some with limitations on the amount of move. A chess piece can reach a certain square and cover it with many different sequencesto arrive at that point. In fact, one of the favorite 3-D seismic survey designs is based on the chessboard concept and achieves coverage with checkerboard moves. Just as in chess, there are many ways to achieve the same objective. The collection of common designs that follow can achieve coverage, but some designs have diagonal or directional properties whereas others do not.
Choosing the best survey design for the intended area is a decision based on many factors. The size of the survey, available equipment, objectives, obstacles, and all the other planning factors go into choosing the right one for a specific survey.
The subsurface sampling is determined by the source and receiver station spacings on the surface. The source and receiver station locations determine a desired bin size. In most cases, there are not enough channels in the field equipment to sample the whole survey without moving the source and receivers around the coverage. The layout of the available receivers at given time and the sources used before moving the layout is called a template. Templates
Figures & Tables
“Written for both the nongeophysicist and the practicing geophysicist, this book collects many of the formulas, principles, concepts, and field approximations of seismic survey design. The basics of 2D and 3D design in this book offer an introduction to the nongeophysicist and provide a good review for the practicing geophysicist. Arrays, obstacles, and special problems are discussed, as are aspects introduced by 3D surveys. The author explores design attributes such as fold, costs, and field time.”