Abstract The Weglowka field is one of the biggest oil fields in the Outer Polish Carpathians, situated north of Krosno between Frysztak and Brzozow in the Subsilesian tectonic unit. The field was discovered in 1888 and has produced 998,220 t of oil and 214.52 million m 3 (7.575 bcf) of gas since exploitation began. More than 350 wells have been drilled in the Weglowka oil field; it was completed in the reservoir intervals that range in depth from 100 to 1200 m (330 to 3900 ft). The Weglowka oil field is now in the final phase of exploitation. Oil is accumulated in several Lower Cretaceous sandstone bodies. The trap is an anticline that is cut by two second-order longitudinal, small thrust faults that subdivide the field between two thrust sheets. Stratigraphic traps probably exist in the Lgota sandstone (the main reservoir), associated with lowstand systems tract sandstones deposited in basin-floor fans. The main seals in the field are the Verovice shales, Lgota Shales, and the younger Godula Shales and Weglowka marls.

Abstract This chapter presents historical remarks and a quick review of knowledge of the occurrence and use of bituminous raw materials in the Carpathians. The most important data on the use of hydrocarbons in the Carpathians in the literature from the 16th century, and on the development of its use, exploration, and exploitation date from the beginning of 19th century. In the laboratories of Lvov and Gorlice, Ignacy Lukasiewicz, the founding father of the Polish oil industry, distilled his first amounts of kerosene and other oil-derivative products. Public lighting of kerosene lamps in a Lvov hospital occurred on July 31, 1853. This date was generally recognized as the beginning of the national oil industry. Also in 1854, the first street kerosene lamp was lit up in Gorlice. These two events showed how important the research of this raw material is. Several natural oil seeps concentrated on the surface signalled the beginning of discoveries of many shallow oil deposits, starting from Stary Sacz, Gorlice, Krosno, Sanok, Sambor, Drohobych, Nadwornaya, Bogorodchany, Kossovo, and going all the way to the Romanian Carpathian Mountains. In this chapter, dynamic development of the petroleum industry from the second half of the 19th century up to the beginning of World War II is also presented, concentrating on gradual activities of many oil companies in the Polish part of the Carpathians. At that time, new drilling and exploratory technologies and oil-distillation processes were developed, causing the growth of the oil industry in the Carpathians and in many countries worldwide.

Abstract This chapter presents a stratigraphic review of reservoirs and their parameters, trap types, and important fields in all of the tectonic units (nappes) in the Polish Outer Carpathians, where hydrocarbon deposits have been discovered and exploited for more than 150 yr. The first part of this chapter is an introduction to the information about the occurrence of reservoir rocks in the Carpathians; however, the variability of these parameters is commonly surprising. Well-known examples are present where reservoir parameters vary greatly even in the same field, but this is a separate problem, and this is only mentioned here. Despite the very large number of wells drilled in the Polish Carpathians, the quantity of detailed petrophysical data is not so large. Good-quality data have been obtained only during the last 30 yr. The most recent and best quality data originate from wells drilled by Polish Petroleum Industry in areas of known fields during research of deeper prospects and from recognized wells. Copyright © 2006. The American Association of Petroleum Geologists. DOI:10.1306/985611M843071 The best reservoir data are from the Skole and Silesian nappes, and these are presented in this chapter in great detail. Within the region of the Outer Polish Carpathians, reservoir rocks are found to have good potential as in shallow as well as deep structures in deposits of Lower Cretaceous to lower Oligocene in age. The majority of hydrocarbon accumulations in the thrusted and folded Carpathians are within structural style traps. Exploration for them throughout the past 150 yr has enabled geologists to recognize their many different types, such as those related to thrust anticlines and folds, but which before were only interpreted as related to folds. Most of the oldest exploited oil accumulations in the Carpathians are of the contractional anticline type, commonly associated with thrusting. Most of these fields can only be illustrated by line-drawn sections based on drilling information because no seismic data are available. Some of the more spectacular traps in the Outer Carpathians are connected to disharmonic thrusted folds, tilted thrust faults, overturned frontal parts of thrust sheets, imbricate fan types, sandstone pinch-out, and traps sealed by asphalt. In this chapter, selected and more important oil and gas fields that can be examples of characteristic hydrocarbon accumulations are also described. The most southern nappe is the Dukla unit, which lies beneath the Magura nappe, where six hydrocarbon accumulations have been discovered in the Oligocene Cergowa sandstone to date. A good example of the hydrocarbon accumulations and tectonic styles of the fields in the Dukla unit is the Slopnice– Limanowa oil and gas field. Here, the hydrocarbons have accumulated in recumbent thrust folds. The Silesian nappe is represented by two important fields: the Bobrka oil field, which is located in the Bobrka anticline, and the Potok oil and gas field in the Potok anticline. Both of these fields have hydrocarbon accumulations in the Ciezkowice and Istebna reservoirs, which are trapped by thrust-related anticlines. The minor tectonic elements, such as thrust-related anticlines and synclines that separate the two fields, however, do not yield hydrocarbons. The Bobrka oil field lies in the world’s oldest area of petroleum exploration and production. This field is taken as the symbol of the Polish and international oil industry and is presented here from a historical point of view. The Potok oil and gas field is located approximately 10 km (6 mi) to the north of the Bobrka oil field. It is one of the six most productive oil fields in the region and produces from an anticlinal structure more than 40 km (25 mi) long. The Skole nappe is a similarly important unit for hydrocarbon exploration. Four oil fields have produced 1.7 million t of oil and more than 180 million m 3 (3.8 bcf) of gas from accumulations in the Menilite sandstone. One example of such an accumulation is seen in the Lodyna oil field. Here, the hydrocarbons are accumulated in a series of almost vertical beds of menilites within pinching out of Kliwa Sandstone.

Abstract The Ciezkowice Sandstone is a lithostratigraphic term used to define a sand-prone succession of late Paleocene–middle Eocene age and is one of the main producing petroleum reservoirs in the Silesian unit of the central and eastern Polish Outer Carpathians. The excellent reservoir potential of these sandstones and their widespread occurrence make them a key objective for future exploration. In this study, the Ciezkowice Sandstone was analyzed using geophysical logs and nearby exposures in the Silesian unit between the towns of Ciezkowice and Krosno. The analysis presented in this chapter has identified as much as four laterally persistent, sand-prone units in the Ciezkowice Sandstone. The dominant lithology of these units is coarse-grained, thick-bedded sandstones interbedded with fine-grained turbidites. The thickness of individual sandstone bodies ranges from 20 to more than 50 m (66 to more than 160 ft) within a gross sand-prone interval of as much as 350 m (1100 ft), in which sand/shale ratios can be as much as 9:1. Sandstone beds are mostly massive to normally graded and commonly display shale clasts, horizontal planar stratification, and water escape structures. The thickest beds are commonly amalgamated and locally display very large-scale trough cross-bedding. These sandstones are interpreted as high-density turbidites. The Ciezkowice Sandstone units are interbedded with pelagic mudstone-dominated tongues, lithostratigraphically termed the “Variegated shales.” Sedimentological features of the sandiest units in the Ciezkowice Sandstone indicate that they were deposited in basin-plain settings during lowstand phases of basin evolution. Copyright ©2006. The American Association of Petroleum Geologists. DOI:10.1306/985617M843071 The Ciezkowice Sandstone represents a second-order lowstand sequence set (basin-floor fan equivalent). The Variegated shales were deposited during transgressive and highstand systems tracts, when sand supply to the basin was reduced significantly. Each Ciezkowice Sandstone–Variegated shale cycle is interpreted to represent a third-order depositional sequence in a lowstand sequence set of latest Paleocene to middle Eocene age. Several subunits of the Ciezkowice Sandstone provide good examples of basin-floor fan-stacking patterns characteristic for deposition in lowstand basin conditions.

Abstract A genetic analysis of oils and potential source rocks and their mutual correlation from three areas of hydrocarbon occurrence in three tectonic units (thrust nappes), Subsilesian, Silesian, and Dukla nappes of the Outer Carpathians in Poland, between Gorlice in the west and Krosno to the east, revises existing opinions on the genesis, migration, and accumulation of hydrocarbons in this part of the Carpathians. One of the important hydrocarbon accumulations occurs in the Subsilesian unit (Weglowka oil field). Detailed geochemical studies show that the oil that accumulated in the Weglowka oil field is the same type as the oil that accumulated in the Potok anticline located about 10 km (6 mi) to the south in the Silesian nappe and derived from the same Oligocene Menilite shales source rock. The oldest known source-prone interval in the Subsilesian nappe is the Verovice shales (Lower Cretaceous), which are likely to have produced the hydrocarbons found in the nearby Wola Jasienicka field located 8 km (5 mi) to the east from the Weglowka oil field. The lower Istebna Shales (Upper Cretaceous) that occurred in the Silesian nappe in the area of Potok anticline could be good source rocks for oil. It is also possible that hydrocarbon generation occurred during several stages, and that mixing of oils derived from Menilite beds and Istebna Shales could have occurred in this area. Similar studies have been made in the southern part of the study area around the oil-rich Gorlice region in the Silesian nappe. This study indicates that the oils accumulated in fields of this region were generated from the Menilite shales of the Dukla nappe, which occurred in tectonic windows in the Magura nappe. Copyright ©2006. The American Association of Petroleum Geologists. DOI:10.1306/985618M843076 The tectonic relationship of the producing fields in the Weglowka–Potok clearly shows the occurrence of several major syncline around the fields. The deepest are to the south of the Wola Jasienicka and Potok fields, which could represent the generative kitchen for these fields during the different stages of Carpathian thrusting. In addition, computer-generated simulations of oil generation in the vicinity of Gorlice and Potok areas suggest hydrocarbon generation and expulsion during the middle Miocene to Pliocene (Holocene).