Ludger Mintrop

By Gerhard Keppner
Hannover, Germany

On November 19, 1924, an oil exploration well in Texas, not far
from Houston, hit the caprock of a salt dome exactly at the predic- 
ted depth. The oil world was confounded. Who had succeeded here 
in predicting so precisely the top of a salt dome, indeed the salt 
dome  itself? Who had the philosopher's stone? Something strange 
was going on. The Houston Post Dispatch that day described the 
case as follows:
...the detailed mechanism of the instrument yet remains a mystery to all but
    a selected few in the oil industry. These few refuse to disclose the secret
    workings of a machine which has accurately pointed out the location of 
 Talk then was of a German patent and of scientists who had come
from Germany and who understood how to use this magic. Ludger
Mintrop was the wonder doctor. Using earthquake seismology as a
basis, he had laid the foundations of "applied" seismics, applied in the sense of being technically and economically practicable and significant. He unmistakably made his ideas known, created a tool 
in the form of SEISMOS in 1921, made his crews swarm in Europe and soon afterwards in the New World-- and was successful. And 
success in this case meant the introduction of applied seismics as 
a decisive means in the exploration of oil and gas. The spark had ignited: the number of geophysical companies in the US exploded, and  among those founded at the time were the most famous names in the business. The breakthrough was not long in coming, as reali- zedby the avalanche of new salt dome discoveries and conse-
quently oil finds in Texas and Louisiana.
 Forerunners and Mintrop's historical role. Regarding Ludger Mintrop as the "founder" of applied seismics rather than the "inventor" is quite intentional. Another great inventor, namely Goethe, made his invention Mephistopheles proclaim, something we all realize to a certain extent:
      Who can think of something stupid, who of  something clever, of  which antiquity has not already thought!....
The idea of applying seismology to the investigation of rock complexes had previously been seized upon by the Irishman Robert Mallet in 1846. He used gunpowder as the energy source and in 1859 determined the velocity of surface waves in sand and granite.  John Milne (1885) continued with similar experiments and introduced the drop-weight as an energy source. During the subsequent years numerous scientists worldwide worked on the theoretical and practical application of seismic methods for investigating the subsurface. Just a few of those were August Schmidt (1888), Ferdinand Fouque and August Michel-Levy (1889), A. Belar (1901), Andrija Mohorovicic (1910), and Reginald Fessenden (1917).
The eminent seismologist from Göttingen Emil Wiechert, whose pupils included such great minds as Beno Gutenberg and  L. Geiger, published in 1907 together with Karl Zoeppritz, his epochmaking work Über Erdbebenwellen. Other work  followed. Nevertheless, Wiechert the teacher still needed one pupil to search for and find the way from theory to the practical, the profitable and with that the commercal application. He was to get him in Ludger Mintrop, the mining surveyor from the Ruhr district. For the historical part that Mintrop was to play, the discipline of mining surveying proved extraordinarily provident. The geologists of 
this age had scarcely a notion of physics and mathematics and their methods and possibilities. The physi- cists for their part had not the remotest conception of geology and therefore did not feel the need to attack geological problems with physical means. Mintrop's knowledge, however, covered both fields in an ideal way.  Georg Elliott Sweet wrote in his History of Geophysical Prospecting:
   In this respect Mintrop was unique for his time. Emil Wiechert could have done it (could have realized his own ideas) 
   except that he was not of a temperament to mix in the trials and buffets of a commercial enterprise...Mintrop, with a 
   good foundation  in both physical and geological principles, had the natural endowment to bring about the first big 
   victory in the conquest of  the subsurface.

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