In its first three years of commercial service, continuous velocity logging has been used in more than 900 wells to date. The data obtained indicate that the velocity log will make valuable contributions to the total information obtainable from a drilled hole.
The velocity measurements in the borehole are obtained over short intervals from the travel time of pulsed sound waves through the sidewall. This measurement is a function of the elastic coefficients of the formations logged and is affected principally by degree of compaction and geologic age.
The velocity log provides an additional parameter not previously measured in boreholes. Geologists are finding the log valuable for correlation, stratigraphic and lithologic identification, and porosity and fluid content studies.
Continuous velocity logs, properly calibrated, provide more accurate and detailed velocity information than is provided by well geophone data alone, and are rapidly replacing the conventional well velocity survey. Other geophysical applications include seismic reflection identification, the determination of the actual reflection depths, and laboratory studies of synthetic seismic reflections.
Magnolia’s contribution to the exploration industry of the development of the velocity logging instrument, and then its release commercially, have made presentation of this material possible. The writers express appreciation to Magnolia Petroleum Company, Sinclair Oil and Gas Company, Warren Petroleum Corporation, Ginther, Warren, and Ginther, and Seismograph Service Corporation for permission to use some of the velocity logs presented.