Bentz, Alfred Theodor

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(b. Heidenheim, Germany, 26 July 1897; d. Hanover, Germany, II June 1964)

petroleum geology, paleontology.

Bentz, son of Karl Alfons Bentz, a confectioner, and Pauline Adelheid Keller Bentz, was for decades the most important German petroleum geologist; he greatly influenced the exploitation of oil and natural gas in Germany and in other countries. When he was young, the great variety of fossils of the Swabian Juras aroused his interest in geologs and paleontology, subjects that he studied, after his military service in World War I, at the universities of Tübingen and Munich between 1918 and 1922. Among his teachers were Edwin Hennig at Tübingen and Ferdinand Broili at Munich. His doctoral dissertation dealt with the stratigraphy of the Middle Jurassic and the tectonics at the western rim of the Nördlingen Ries at a time when its origin through the impact of a meteor was not yet known. (Bentz always remained skeptical of the impact theory.)

After serving as an assistant to Hennig at Tübingen (1922–1923) and then joining the Prussian State Geological Institute at Berlin in 1923, Bentz continued his biostratigraphic studies of Bajocian ammonites, deeding intensively with paleontological taxonomy and nomenclature.

In 1925 Bentz began the geological mapping of northwestern Germany and, at the same time, became familiar with petroleum geology. This was a twofold task that was to prove decisive for his further work. His careful study of the stratigraphy and tectonics of the German-Dutch border region—where, between 1904 and 1907, there had been unsuccessful attempts to drill for oil—contributed much to the later exploitation of hydrocarbons.

Bentz’s geological and paleontological experience provided him with the thorough knowledge that enabled him to accept a position in the Section of Petroleum Exploration at the Prussian State Geological Institute in 1929. Numerous drillings during the 1920s, as well as the first productive oil fields near Hanover, offered Bentz the opportunity to investigate the complex problems connected with the origin and the deposits of petroleum. During these years the rotary boring method, developed in the United States, and applied seismics—for which Ludger Mintrop, the German originator, had found an interest only in the United Stales—became known in Germany.

In 1932 Bentz undertook the first comprehensive survey of the geological conditions leading to the formation of German petroleum deposits and areas that seemed likely to yield petroleum. A 1934 visit to the oil fields of the United States strengthened his decision to begin a systematic search for petroleum in Germany. His work in 1934 led to the establishment of the Institute for Petroleum Gcology, of which he was a director. In 1940 the German government incorporated this institute—as a section for oil exploration—into the State Geological Institute. Owing to his organizational skills. Bentz achieved a nonpolitical collaboration between private oil firms and the state institute. Even during World War II he was successful in giving research priority over exploitation.

During the 1930’s it was found that the most favorable preconditions for the formation, as well as discovery and exploitation, of petroleum deposits existed in the northwestern German basin (56, 000 square kilometers, or 21, 616 square miles) with its 8, 000 meters (about 26, 000 feet) of marine sediments composed of clay and sand from the Rhaetic to the Lower Cretaceous. Here, sandstone proved to be potentially oil bearing. Oil was found especially in the flanks and the apex of numerous salt domes. the rise of which, beginning in the Jurassic, intensified during the neo-Cimmerian orogenesis. With increased drilling, oil was also found in anticlines that had formed in a purely tectonic way, and in other tectonic structures, such as petroleum traps at faults and edges of sedimentary troughs.

Oil deposits were assumed to have originated at the place of their occurrence. In 1913 Johannes Stoller supposed that in the neighborhood of the salt domes, water of high salinity had caused masses of plankton to die out, and from those plankton oil had formed. The tectonic conditions and the preferential binding of oil to sandstone, however, testified to the fact that oil had moved secondarily to the present deposits. Bentz insisted that one had to differentiate between primary (mother) rocks and secondary (storage) rocks. An oil deposit discovered in the Permian salt of Thuringia (1930) and gas deposits found in 1934 in the Upper Permian of the Ems region pointed to the Upper Permian as the most important mother rocks. This, however, conflicted with the fact that no oil had been found in the upper Bunter strata, through which the oil rising from the Upper Permian would have had to pass.

For a few years after World War II German petroleum research was directed by Bentz—now head of the State Geological Institute of Lower Saxony. He began a reciprocal relationship with geologists outside Germany. He wrote numerous reports, publishing in German and foreign periodicals and in collected works. In 1953 Bentz was the first to draw attention to a potential deposit of hydrocarbons in the subsoil of the North Sea off Germans. In 1960 he announced at the World Power Conference in Madrid that the German output met 30 percent of Germany’s domestic requirements.

After the war, German petroleum research results were increased under the influence of Bentz in five ways: (1) by more detailed information about the stratigraphy and structure of ihe northwest German basin with its submarine troughs and sills; (2) by the discovery that the origin of petroleum is not confined to the Upper Permian, but can also be in numerous horizons of the Jurassic and the Lower Cretaceous sediments; (3) by the recognition that petroleum occurs, owing to its buoynancy, mainly in secondary deposits (edges of troughs, salt domes, anticlines); (4) by the awareness that apart from tectonic and salt-tectonic oil traps, there are other traps conditioned stratigraphicalls and by the horizontally changing fades (stratigraphic and depositional oil traps, requiring a paleontologically exact stratigraphy); and (5) by the knowledge that the oil deposits of the Upper Rhine rift valley and of the molasse of the Alpine rim exploited after 1945 originated in early Tertiary rocks.

Successful petroleum exploration depends on the collaboration of the natural sciences, technology, the initiative of the entrepreneur, and the international exchange of methods, techniques, and expertise. Bentz was skillful in harmonizing and coordinating these factors.

During the last years of his life, Bentz was among the experts concerned with future energy supplies. Indeed, he was most optimistic about the availability of petroleum and natural gas to future generations. Numerous institutions in many countries sought his advice about prospecting for hydrocarbons, advice that he gave on the spot. Bentz was the editor of Lehrbuch der angewandten Geologie (1961–1969) and Beiträge zur regionalen Geologie der Erde (published since 1961). In Geologisches Jahrbuch and in the accompanying supplements published by his institute, he attached great value to a well-balanced representation of all disciplines, including paleontology. He also devoted numerous talks and papers to the dissemination of geological knowledge.


I. Originai Works. Bentz’s writings include “Über Dogger und Tektonik der Bopfingcr Gegend,” in Jahresbericht und Mitteilungen des oberrheinischen geologischen Vereins, n.s. 13 (1924), 1–45, his dissertation; “Die Garantianschichten von Norddeutschland mit besonderer Berücksichtigung des Brauneisenoolith-Horizontes von Harzburg,” in Jahrbuch der preussischen geologischen Landesanstalt, 45 (1924), 119–193; “Die Entstehung der’ Buntcn Breccie,’ das Zentralproblem im Nördlinger Ries und Steinheimer Becken,” in Zentralblatt für Mineralogie, Geologie, und Paläontologie, sec. B. Geologie und Paläontologie (1925), 97–104, 141–145; “Über das Mesozoikum und den Gebirgsbau im preussischholländischen Grenzgebiet,” in Zeitschrift der deutschen geologischen Gesellschaft, 78 (1926), 381–500; “Zur Entstehung des Erdöls in Nordwestdeutschland,” in Zeitschrift des Internationalen Bohrtechniker-Verbands, 16 (1927), 307–308; “Tektonische Untersuchungen in hannöverschen Erdölgebieten,” in Zeitschrift der Deutsehen geologischen Gesellschaft, 79 (1927), 241–254; “Salzstöcke und Erdöllagerstätten,” in Petroleum, 24 (1928), 1157–1164; “Über Strenoceraten und Garantianen, insbesondere ans dem Mittleren Dogger von Bielefeld,” in Jahrbuch der preussischen geologischen Landesanstalt, 49 (1928), 138–206; “Geologische Voraussetzungen für das Auftreten von Erdöllagerstätten in Deutschland,” in Zeitsehrift der Deutschen geologischen Gesellschaft84 (1932), 369–389.

“Die verschiedenen Endölhorizonte Norddeutschlands, deren primäre oder sekundäre Entstehung,” in Jahrbuch des deutschen nationalen Komittees fur die intenationalen Bohrkongresse (Berlin, 1932), 21–88; “Geologische Studienreise in nordamerikanischen Erdölfeldern,” in Petroleum, 30 (1934), 1–43; “The History of the German Geological Survey,” in Geological Magazine, 84 (1947), 169–177; “Die Entwicklung der Erdölgeologie,” in Zeitsehrift der deutschen geologischen Gesellschaft, 100 (1950), 188–197; “Die Kntwicklung der deutsehen Erdölproduktion—Rückblick und Ausblick,” in Erdöl und Kohle, 6 (1953), 823–827; “Über die Herkunft des Erdöls in Deutschland,” in Roemeriana, 1 (1954), 361–384; “Geophysik und Erdölerschliessung in Deutsehland,” in Erdöl und Kohle, 9 (1956). 278–280; “Relations Between Oil Fields and Sedimentary Troughs in Northwest German Basin,” in Lewis G. Weeks, ed., Habitat of Oil: A Symposium (New York, 1958), 1054–1066; “Results and Prospects of Oil and Natural-Gas Research in Western Germany,” in World Power Conference, Sectional Meeting, Madrid (Madrid, 1960), 1–21, written with H. Boigk; “Bildung und Erschliessung der Energiequellen der Welt aus geologischer Sicht,” in Brennstoff-Wärme-Kraft: Zeitschrift für Energietechnik und Energiewirtschaft, 14 (1962), 569–579; and, as editor. Lehrbuch der angewandten Geologie, 2 vols. in 3 (Stuttgart, 1961–1969), the two parts of vol. 2 completed by H. J. Martini; and Beiträge zur regionalen Geologie der Erde, vols. 1–4.

II. Secondary Literature. On Bentz’s life and work, see Wolfgang Schott. “Alfred Bentz als Wissenschaftler,” in Geoiogisches Jahrbuch, 83 (1965), xxix-xlviii, with an extensive bibliography.

Helmut HÖlder