Analysis of High Resolution Seismic Data1
High resolution data analysis can provide the detail commonly absent in deep seismic shooting. Greater detail provides a means for seafloor mapping, subcrop mapping, and mapping of shallow structures, contours, and hydrocarbon accumulations and seeps. Accurate shallow mapping also offers a means to select a drilling site by providing data for a potential drilling and construction hazard map, and helps the engineer plan for the task by providing geotechnical information for foundation design.
High resolution geophysics should more properly be termed, high resolution acoustics or else continuous acoustic profiling. Acoustic systems provide analysis by using sound-generating devices, sound receivers, and graphic recorders which define the water depth and provide a cross-sectional display of the sea bottom and subsurface lithology. Commonly, more than one acoustic device is used simultaneously to achieve different data for different studies. Such a system is typically referred to as a multisensor acoustic system.
Different acoustic systems provide different data. Water depth systems define water depth for bathymetric mapping; tuned transducers define bubble clusters, marine flora, and fish accumulation; side-scan sonar defines bottom irregularities, outcrops, and bubble clusters; while acoustic subbottom profilers penetrate the seafloor to provide subsurface data. Of course, filtering and stacking improve resolution on some acoustic systems just as they improve resolution in deep seismic shooting.
Figures & Tables
Papers from a research symposium at the 1975 American Association of Petroleum Geologists and supplemented by later reports became “Seismic Stratigraphy Applications to Hydrocarbon Exploration”, one of AAPG’s best-selling book publications. Dramatic improvements in seismic imaging were demonstrated, a result of developments in seismic data quality and the processing capability of electronic technology. Twenty-eight articles are grouped into three sections. The first describes principles that both permit and also limit interpretations. The second section presents sixteen articles that describe the qualitative approach to stratigraphic interpretations of reflection records, and the final section presents techniques and examples of modeling. Of particular interest are a series of eleven papers in the second section under the subject heading of “Seismic stratigraphy and global changes of sea level”. Prepared by P. R. Vail, R. M. Mitchum and others from Exxon, they describe the regional unconformities and stratigraphic changes resulting from sea level fluctuations, and the manner in which these changes can be interpreted from seismic surveys. For many individuals within the oil industry who purchased this book, it was their first introduction to the modern concept of sequence stratigraphy that would have a major impact on the methodology of petroleum exploration.