Oil and gas fields in the Carpathians and the Carpathian Foredeep

Abstract

A b s t r a c t . Southeastern Poland is one of the oldest petroleum provinces in the world. Although hydrocarbon production has been conducted in this region since the middle of 19th century, there is still a good potential for more discoveries. 9 billion cubic meters of high methane gas reserves reported in the years 2000-2006, when combined with the previously discovered gas fields, essentially satisfy gas demand for this area. Currently, Miocene deposit of the Carpathian Foredeep is the most prolific exploration target area with more than 100 discoveries of high methane gas. The total reserves of these fields are 138 billion cubic meters, and the cumulative production is more than 90 billion cubic meters of natural gas. Large gas fields in terms of area and reserves that have already been discovered are followed by present discoveries of fields with relatively smaller area, their reserves are up to 2 billion cubic meters. Current exploration efforts are focused on good understanding of the sub-miocene basement configuration as well as detecting of seismic anomalies directly related to natural gas accumulations. Another very important element of exploration strategy for Southern Poland is the Mesozoic and Paleozoic deposits of the Carpathian Foredeep. The most prospective for discovering of sizeable hydrocarbon fields are Cretaceous (Cenomanian) sandstones and Upper Jurassic carbonates, locally also Middle Jurassic sandstone as well as Lower Carboniferous and Devonian carbonates. So far 13 gas fields and 10 oil fields have been discovered in the Mesozoic and Paleozoic of the Carpathian Foredeep and the sub-Carpathian basement with booked reserves of 7.5 billion cubic meters of natural gas and 4.7 million tons of oil. The cumulative production amounts to 6.1 billion cubic meters of gas and 4.3 million tons of oil. Different exploration problems have been encountered in the Carpathians. Most of the fields which have been discovered in the Flysch Carpathians occur in shallow, steep, narrow, commonly thrusted and faulted folds. Oil and gas fields discovered so far in the Carpathians have small reserves. Additionally, discovered and booked reserves of existing oil and gas fields are depleted to a large extent. 17 gas fields and 67 oil fields have been discovered in the Carpathians. Booked reserves amount to 16.6 billion cubic meters of natural gas and 12.3 million tons of oil. Cumulative production has been 15.2 billion cubic meters of gas and 11.9 million tons of oil. To sum up, it should be emphasized that the bulk of gas reserves discovered, booked and developed recently in Southern Poland comes from the autochthonous Miocene deposits. This trend, which involves high methane gas, is expected to continue for the next few years. Potential oil discoveries can be attributed mainly to the flysch Carpathians and Paleozoic, but requires more research and further exploration on a larger scale.