Hydrocarbon Resources of the Polish Outer Carpathians—Reservoir Parameters, Trap Types, and Selected Hydrocarbon Fields: A Stratigraphic Review
Piotr S. Dziadzio, Zenon Borys, Stanisław Kuk, Emil Masłowski, Jaromir Probulski, Małgorzata Pietrusiak, Adam Górka, Jan Moryc, Anna Baszkiewicz, Piotr Karnkowski, Paweł H. Karnkowski, Marek Pietrusiak, 2006. "Hydrocarbon Resources of the Polish Outer Carpathians—Reservoir Parameters, Trap Types, and Selected Hydrocarbon Fields: A Stratigraphic Review", The Carpathians and Their Foreland: Geology and Hydrocarbon Resources, Jan Golonka, Frank J. Picha
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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.
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 m3 (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.