Deep Tests in Denmark 1935-1959

Abstract

The exploration activity which resulted in the 31 deep tests reported on in this paper is briefly outlined in the introductory chapter.

Mr. F. Ravlin initiated exploration by drilling the two wells at Harte. He held the concession covering all of Denmark from 1935 to 1938, when Gulf Oil Corporation acquired the concession. A large amount of geophysical and geological work was subsequently carried out under the aegis of the Gulf Oil Corporation, and until 1957 eighteen deep tests were completed. Finally, during the period from 1957 to 1959, when the Standard Oil Company of New Jersey was the concessionaire, seismic work was carried out in selected areas, and 11 deep tests were drilled.

Among the geological results the most important one was the proof of a well developed Pre-Upper Cretaceous sedimentary basin in Denmark. The rock column includes Pre-Cambrian, Cambrian, Ordovician, Silurian, Permian, Triassic, Jurassic, and Lower Cretaceous formations. A thick evaporite sequence in the Upper Permian Zechstein is the prerequisite of the salt dome province discovered in North Jutland.

Oil shows were encountered in dolomites of the Zechstein in South Jutland, but these petroliferous beds proved unproductive. A short blow out of petroleum gas was, moreover, experienced while drilling in the Suldrup salt dome in North Jutland. It is assumed, that a Zechstein dolomite was the reservoir.

An abbreviated well log is given for each of the 31 deep tests. Graphic logs of the wells arranged into simple cross sections are found on plates 18 to 22. Bibliographic references regarding fossil species of importance for biostratigraphy are given in the Danish annex at the end of the paper. Most of the species concerned are illustrated on plates 1 to 11.