Wybrane aspekty ekonomiczno-geologiczne wykonywania głębokich otworów wiertniczych na Niżu Polskim

Andrzej Witkowski

Abstract


SOME ECONOMIC-GEOLOGICAL ASPECTS OF DEEP BORE HOLES MADE WITHIN THE POLISH LOWLAND AREA

Summary

The article presents same remarks related to the deep bore holes made by various geological enterprises of the Central Office of Geology for the Geological Institute. As a basis for clearing of accounts between the investor and the contractors serve price-lists for deep drillings CWG 3/72. Based on the critical analysis of the individual sections of a price-list the author calls in question the legitimacy of the clearing of accounts with regard to the interval 3000-3200mm for drillings to a depth of 3200 m according to the prices corresponding to the interval of 4500 m, and he postulate for the distinct dependence of the prices of the individual sections upon the type of drilling rig used. This postulate particularly concerns drillings to a depth 3200-3500 m, where the differentiation of the prices of assembly and disassembly of the same drilling rig – calculated in the category to 4500 m, instead in a lower category appropriate to a given type of rig – amounts 2 million zlotys. The differentiation of prices of 1 m of drilling depends mainly upon the so-called category of rock and upon the mode of drilling - using a bit or a core drill. The categories of rocks presented in the price-list differentiate prices according to the individual depth intervals - from 614 to 127.500 zlotys. This causes uninterrupted discussion between the drilling service of the executor and that of the investor. On the basis of many years experiences one can say that the distinguished categories do not objectively reflect the real outlays related to the drilling of rocks of various types, according to the classification. This, among others, is proved by a considerable differentiation in mechanical progress in rocks of the same category. The present author suggests to work out a new classification especially based on the research of drillability of rocks. In addition to this he gives a short review of lithological types and categories of rocks according to the obligatory classification of rocks that occur in the individual geological formations within the Polish Lowland area. It also appears that so differentiated prices between the core drilling and the coreless drilling are unjustified. There are given examples where rocks characterized by low drillability have been pierced by diamond core drill at the intervals destinated for drilling using normal bits, and the results have naturally been better than when drilling with bits. Taking into account the general tendency to diminish the scope of core recovery to introduce modern drilling technology the author emphasizes that the significance of the drilling cores obtained by the Geological Institute from the investigation bore holes de considerable, and that this geological material cannot be replaced by other auxiliary research methods. The scope of coring in bore holes made at present by the Geological Institute ranges from 15 to 25 per cent. During the analysis of the performance of deep bore holes attention has been paid to considerable production reserved related to the elimination of standstills caused by failures and fishing works (Table 1), and to economical advantages which can be got by the geological enterprises. Emphasized are coordination of works, and introduction of new methods (particularly samplers) which cut down time of sampling after drilling process. The best results, as concerns deep drillings, were noted - within the Central Office of Geology - by the Geological Enterprise Warsaw, which in June 1972 completed the bore hole Kościerzyna (5202 m), the deepest one in the Polish Lowland area. This enterprise broadly introduced the laboratory service of deep drillings, installing some stationary and movable laboratories of "Geoservice" type, equipped with research instruments of French production. The geological service of drillings is carried on by the geologists of the geological, supervision, for the most part by the workers of the geological enterprises and by the geologists of the geological inspection of the Geological Institute.

 


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