Land Multiline Recording Techniques: Selected Case Histories

Daniel D. Hollis

With the advent of multichannel CMP (common mid-point) recording, especially with channel capacities reaching the 1,000 to 2,000 channel range, multiline recording has become a useful tool in seismic exploration and exploitation. The main advantage of multiline recording is the economy of scale it offers when acquiring large data volumes. More data per source point means fewer source points are required for any particular area and, hence, a reduced cost per area. However, multiline recording techniques have been developed to achieve various geophysical or operational objectives.

Effective seismic techniques require proper spatial sampling of the subsurface. Spatial sampling can be thought of, in a two-dimensional (2D) survey, as the line spacing within the seismic grid as well as the inline CMP spacing, or for a three-dimensional (3D) survey, the bin size. Adequate spatial sampling can be difficult to achieve because of economic or operational factors. Economically, denser spatial coverage per unit area will drive up the cost of a survey and may make a survey uneconomical if acquired in a conventional manner. Operationally, poor access due to topographic or cultural obstructions may prevent adequate spatial sampling.

Selected case histories represent the use of various land multiline recording techniques for different geophysical and operational areas and objectives. Geophysical objectives include dense spatial sampling achieved through swath 2D and 3D recording, crossline noise cancellation, and beam steering of crossline reflected energy. Operational objectives include the economy of the survey and obtaining adequate subsurface coverage in an area with surface obstructions. Each case history includes a description of the geological objective and environment, a discussion of the development and implementation of the multiline technique used, examples of the resulting seismic data, and comments on the effectiveness of the technique.

AAPG Search and Discovery Article #91024©1989 AAPG Pacific Section, May 10-12, 1989, Palm Springs, California.