engleski

Hydrocarbons in Croatia

In the middle of 19th century, there was exploration, production and refining of oil in Croatia. According to historic sources, this means that Croatia was in this sense preceded only by a small number of European countries Russia, France, Romania and Germany. It is also noted that usage of oil has a long tradition, especially for the medical purposes. There are several old scripts dating from the 14th and 15th century in which medicaments like “asphalt” and “petroleum” are listed. It is also worth mentioning that in the old pharmacy of Dubrovnik "olio petrolio" could have been bought in 15th century. It was either produced in the region, or probably imported by Asian merchants. It is also proven that the Dubrovnik merchants in 12th century bought and transported tar. The first detailed description of petroleum findings in the Croatian part of Pannonian basin was composed by two explorers, who came from the Budapest University. This was in 1781 and they were Mathie Piller and Ludovicus Mitterpacher. They spent a month in Slavonia and visited several locations. In the vicinity of Gojlo, they found bitumen and petroleum, and in Bačindol near Nova Gradiška, they observed the petroleum flowing down the creek and tested it by burning. Organised production commenced in the beginning of 19th century in a number of petroleum shafts near the Peklenica village in the Mura river valley. On the northern flank of the Sava river valley, where this excursion will be driving through, exploitation of oil began in the middle of 19th century. Several petroleum shafts were dug in the Mikleučka village (near Kutina) and in the villages of Paklenica, Petrovo Selo and Bačindol (near Nova Gradiška). The petroleum mine in the vicinity of Mikleučka, named "Martin", produced from 1865 till 1943. It had a 72 m deep vertical shaft and 55 m long gurny with 9 secondary drifts through which oil leaked and accumulated in the shaft. Several hundreds of litres per day were hoisted up and processed in a small local refinery. The mine is now watered and bitumen is leaking in the creek much in the same way as it was before. There are recent initiatives to restore it, to a kind of geological and petroleum-engineering museum, which might be complemented with a tour of the nearby MRAMOR BRDO oil field (52) and exhibition of the core material stored by INA Naftaplin at the same location (EBEČIĆ et al., 2000). In the 1855-1940 period, a total of 180 wells were drilled at 15 perspective locations in Croatia. A 905 m deep well was completed in 1905-1906 near Kloštar Ivanić. There was a strong eruption of gas and the well was abandoned. Another 350 m would have resulted in a major success but this was achieved 40 years later in more favourable technological circumstances (KLOŠTAR IVANIĆ oil and gas field 41). Of the numerous recent oil and gas fields in the Sava depression (nos. 39-58) the most important ones will be mentioned. All of them can be observed driving on the highway from Zagreb to Slavonski Brod. They are all characterised by HC accumulations in the Upper Miocene sandstone-shale sequence. The first one that can be seen is the IVANIĆ GRAD oil field (47) that is actually crossed by a highway approximately 35 km SE of Zagreb. It is a faulted anticline that contains multiple sandstone reservoirs (fine-grained and poorly cemented), mostly of Pannonian age, at depths of over 1500 m. The other three large fields are lined up in a SE direction. They can all be observed on the right-hand side at intervals of around 10 km Žutica, Okoli and Stružec. ŽUTICA is an oil and gas field (48) with a number of reservoirs of Pannonian (oil-saturated) and Pontian (gas-saturated) age in the 1350-1950 m interval. It has the structure of an asymmetric brachyanticlyne and around 300 wells were developed. The OKOLI gas field (49) produced from the same, but more deeply situated sandstone reservoirs (1700-2200 m), that were originally saturated with gas condensate. The porosity and permeability was less favourable, but since this was gas it didn’t matter much. The structure of the STRUŽEC oil field (50) can actually be seen on the surface as a small hill on the right-hand side of the highway just after the Popovača junction. It is also marked by the appearance of Pleistocene sediments on the surface surrounded by Holocene sediments, which implies that the structure is very young (or renewed). This structure was already drilled by the Germans during the World War II occupation, but the production started in 1960. Most of the oil and gas reserves are found in the Pontian layers and some in Pannonian layers. The main reservoirs are sands, sandstones and fractured marls. The Lipovljani structure lies under the hills on the left-hand side of the highway 15 km past the Kutina junction. This is an extensively faulted anticline with multiple productive horizons of the Upper Miocene at the 800-1500 m interval. The LIPOVLJANI oil and gas field (54) is known for its poorly cemented sands, very frequent lateral changes of facies and numerous reverse faults. ŠEBEČIĆ, B., ŠMIT, Z. & BELUŠIĆ, M. (2000): The Natural Source of Hydrocarbons near Mikleuška – Potential Mining Monument in Nature (in Croatian with an English abstract).- In: VLAHOVIĆ, I. & BIONDIĆ, R. (eds.): Second Croatian Geological Congress, Cavtat – Dubrovnik, 17-20.5.2000., Proceedings, 857-862, Zagreb.

Hydrocarbons

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