Practical Problems And Special Situations
There are many practical considerations in field design, some of which do not yield to formulation as easily as the basic sampling parameters. The influence of the lithology of the target on line orientation and location has been noted. The equipment available at the time of the survey, costs of the survey, environmental considerations, and area-dependent scheduling are all part of the design of the survey. Information on the survey area in the form of maps, seismic data, well logs, geology, scouting, and objectives must be gathered prior to the design.
Equally important is to involve all the departments in the survey design and determine if there is someone in the company experienced in the area. Field tests and computer model tests are also a normal part of the design sequence. Marshaling a crew may involve personnel with special skills such as helicopter pilots, special mechanics, and equipment unique to the particular area. Situations not found in the information-gathering stage that require modification of the design will frequently arise when the crew takes the field.
These factors will be discussed subsequently as part of the 3-D design sequence but apply to 2-D surveys as well. Much of the technology and practical aspects are found in company proprietary manuals and not in published form.
One of the problems for 2-D surveys provided experience that proved to be useful in designing 3-D surveys. Field conditions sometimes prevented the layout of lines in the desired linear form. The lines were crooked and violated
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.”