SEISMIC METHODS 913 



GENERAL OUTLINE FOR PLANNING SEISMIC EXPLORATION. 

 I. Preparation (prior to selection of method and employment of geophysical crew). 



1. Check availability and price of acreage. Currently, the attractive acreage may 

 be leased, but the lease may be short term or in the hands of an owner with 

 whom a deal can be worked out. 



2. Find out results of previous exploration work in the area, especially geophys- 

 ical. Determine particularly which method has yielded best results and the 

 extent of its use; check the completeness of the earlier geological and geo- 

 physical work. 



A. If seismograph appears to be the logical tool, find out whether refraction 

 or reflection method can be better used. 



B. If reflection method appears to offer more promise, determine the best 

 technique to use, i.e., correlation, continuous profiling, or dip shooting. 



C. From the probable geology and the previous history of the area, determine 

 formations from which reflections or refractions can be expected. 



3. Thoroughly investigate the geology of the area to be explored. 



A. Check cuttings, scout tickets, drillers' logs and electric logs for oil or gas 

 showings in all wells in area. 



B. Check all correlations, particularly those to which geophysical work may 

 be tied and those critical to the prospect. 



C. Determine intervals of convergence or divergence, unconformities, facies 

 changes and possible faulting. 



D. Construct subsurface structure maps, preferably near and conformable to 

 potential seismic reflecting or refracting horizons. 



E. Construct such isopach maps or cross sections as appear useful. 



F. Review carefully and in detail the literature of the area. This calls for an 

 exhaustive search. 



G. Examine files for all possible previous geological or geophysical work in 

 the area, including surface, core drill, old subsurface, seismograph, gravity, 

 electrical and magnetic work. Analyze, evaluate and integrate this work 

 into the subsurface studies. 



4. Determine who drilled test wells in the vicinity of likely prospects, and when 

 and why they were drilled. Oil fields are often found on prospects which have 

 been condemned. Determine significance of these test wells. 



5. Secure outlines of blocks of land previously acquired in the area and deter- 

 mine, if possible, the reason for acquisition. 



6. After a critical analysis of all the above information, list all prospects devel- 

 oped, grading them according to promise based on all available information. 



7. Secure available road maps, topographic maps, and aerial photos in vicinity of 

 prospects to determine whether and how prospects can best be worked. 



8. Investigate type and cost of equipment required for the work, the relative 

 cost of various geophysical techniques and probable relative value of the data. 



9. Investigate previous geophysical work of competitors in the area to determine 

 how thoroughly prospects selected may have been worked, when, and by what 

 method. 



10. Attempt to secure services of a well-equipped, well-managed crew experienced 

 in the area. Be certain that party will be adequately supervised by the con- 

 tractor. Be sure you know interpretation facilities and experience. Results 

 can be no better than interpretation. 



11. Investigate permit costs and difficulties. 



12. In foreign work, investigate the regulations pertaining to the transporting of 

 men and equipment into and out of that country. 



