document: On 15 January 2020, INA Industrija Nafte d.d. (INA) reached the final depth of 1,739 m (TVD 1,693 m) in wildcat Selnica 1 IS (Istok - East) in the Zebanec mining plot, enclave within a yet to be awarded block - Sjeverozapadna Hrvatska 1 (SZH-1) - in northern Croatia. After encountering wellbore stability issues/circulation losses at total depth, the well was suspended with oil and gas shows - a sidetrack is mooted.  Selnica 1 IS was spudded on 24 December 2019, using the National 402 drilling unit from Crosco Zagreb. The Zebanec mining plot is located close to the border with Hungary and Slovenia. It falls within the Mura Sub-basin, tectonic unit of the Pannonian Basin.  The well was targeting the Lower/Middle Miocene successions, with secondary target in the Mesozoic karstic series. The initial planned total depth was 1,750 m.  Background Information  The Selnica field is the second oldest commercial oil field in the country. Oil seeps have been recorded from the nearby Peklenica region since 1788 and commercial exploitation from shallow mineshafts began in 1868. The first commercial oil well in this field was drilled in 1885. Between 1954 and 1956 Singer drilled the Selnica 1 exploration well to a total depth of 2,814 m and found oil in the Abichi Mb. The field was abandoned in 1965.  News in 2018 was that INA is planning to drill appraisal Selnica 1 IS, but the project was deferred.
summary: Selnica 1 IS (Istok - East) (INA 100%) in the Zebanec mining plot, enclave within a yet to be awarded block - Sjeverozapadna Hrvatska 1 (SZH-1) - in northern Croatia. After encountering wellbore stability issues/circulation losses at total depth, the well was suspended with oil and gas shows - a sidetrack is mooted.