The Upper Cretaceous complex in the central part of the Carpathian Foreland (southern Poland) is relatively poorly recognized and described. Its formations can be classified as unconventional reservoir due to poor reservoir properties as well as a low recovery factor. The main aim of the article is to expand knowledge with conclusions resulting from the analysis of the latest seismic data with the application of seismic sequence stratigraphy. Moreover, the seismic attributes analysis was utilized. The depositional architecture recognition based on both chronostratigraphic horizons and Wheeler diagram interpretations was of paramount importance. A further result was the possibility of using the chronostratigraphic image for tectonostratigraphic interpretation. Two distinguished tectonostratigraphic units corresponding to megasequences were recognized. A tectonic setting of the analyzed interval is associated with global processes noticed by other authors in other parts of the central European Late Cretaceous basin, but also locally accompanied by evidence of small-scale tectonics. This study fills the gap on the issue of paleogeography in the Late Cretaceous sedimentary basin of the Carpathian Foreland. It presents the first results of detailed reconstruction of the basin paleogeography and an attempt to determine the impact of both eustatic and tectonic factors on sedimentation processes.

An integrated geological and geophysical approach is presented for the recognition of unconventional targets in the Miocene formations of the Carpathian Foredeep, southern Poland. The subject of the analysis is an unconventional reservoir built of interlayered packets of sandstone, mudstone and claystone, called a “heterogeneous sequence”. This type of sequence acts as both a reservoir and as source rock for hydrocarbons and it consists of layers of insignificant thickness, below the resolution of seismic data. The interpretation of such a sequence has rarely been based on seismic stratigraphy analysis; however, such an approach is proposed here. The subject of interpretation is high-quality seismic data of high resolution that enable detailed depositional analysis. The reconstruction of the depositional history was possible due to the analysis of flattened chronostratigraphic horizons (Wheeler diagram). The identification of depositional positions in a sedimentary basin was the first step for the indication of potential target areas. These areas were also subject to seismic attribute analysis (sweetness) and spectral decomposition. The seismic attribute results positively verified the previously proposed prospects. The results obtained demonstrate that the interpretation of the Miocene sediments in the Carpathian Foredeep should take into account the depositional history reconstruction and paleogeographical analysis.

Exploration for hydrocarbon reservoirs is currently focused on increasingly difficult targets and geological structures, thus stimulating a growing requirement for new measurement methods and techniques that can provide more detailed information about lithology and reservoir parameter distribution in the vicinity of the target zone. This publication presents a method for increasing the resolution of the recorded surface seismic wavefield in the vicinity of example borehole Well-1 (western Poland) for reservoir horizons of the Rotliegend and Zechstein formations. The main stage of the research was the introduction of frequencies from vertical seismic profiling (VSP) into seismic traces. The shape filter deconvolution procedure was applied based on the operator calculated from VSP data, which was applied to seismic profiles extracted from 3D data. The procedure applied allowed for the reconstruction of higher-frequency spectrum necessary for a detailed imaging of the geological framework of the analyzed reservoir formations. In the next stage, seismic inversion calculations were conducted, both on VSP data (corridor stack and VSP-CDP transformation) and on surface seismic time sections. The results obtained as an acoustic impedance distribution enabled a more comprehensive structural interpretation and detailed analysis of the variability of reservoir properties in the analyzed well area.

A paleokarst system developed in the Upper Jurassic–Lower Cretaceous carbonate complex has been recognized in the Carpathian Foreland area. Well logs testing and core data as well as an acoustic imager, a microresistivity scanner and six-arm dipmeter images were used to identify and analyze the character of the paleokarst features. A detailed interpretation of microresistivity and acoustic image logs allowed for the identification of different types of karst forms, such as caverns; multidirectional fractures, including fractures widened by dissolution; and the type of sediments filling them. The analysis of the seismic survey was conducted by linking the paleokarst characteristic features recognized in the seismic image to the karst intervals determined from borehole data. The set of seismic attributes calculated from the analyzed 3D seismic data, including the RMS amplitude, instantaneous frequency, consistent dip, variance, sweetness and relative acoustic impedance, helped to delineate the zones of the paleokarst distribution. Within the interpreted paleokarst surface developed in the carbonate formations in the study area, there are sinkholes, limestone pavements and valleys. Furthermore, in the northwestern part of the analyzed area, the development of paleokarst forms is related to the presence of a relatively deep branch of a paleovalley formed in the Paleogene, as well as to numerous discontinuities developed in carbonate formations. The development of this type of larger karst form was probably controlled primarily by tectonic faults. The research conducted by the authors of this paper showed the widespread presence of paleokarst features in Upper Jurassic–Lower Cretaceous carbonate formations in the study area. A good spatial identification of the paleokarst surface can be important in a regional context, since the highest part of the profile of carbonate formations is the most important reservoir for geothermal or hydrocarbon resources in this region.

Detailed recognition of the paleoenvironment of sedimentation for the monotonous series of heterolithic sediments of the Machow Formation in the central part of the Carpathian Foredeep is still relatively poor. This study presents an unconventional approach of integrating results of seismostratigraphic interpretation with conclusions from analyses of chemostratigraphic profiles in boreholes. The results obtained from the studies allowed the resolution of the seismic data to be increased, enabling it to be accurately tied to the well data. The studies showed a high consistency between results obtained by the two methods mentioned above, and their combination provided a range of additional information and conclusions that could not be drawn from using a single method. The possibility of correlating interpreted sedimentary sequences with specific elements of the paleoenvironment and stages of the depositional history of the analyzed sedimentary basin was also demonstrated. An important benefit of the integrated interpretation methodology used is the possibility to recognize an apparently monotonous profile of heterolithic formations, which was previously not possible with standard interpretation methods.

The depositional environment of the Machów Formation in the central part of the Carpathian Foredeep is still relatively poorly understood. Although lithological variability, facies diversity, and depositional history have been described in many publications, the paleoenvironment of sedimentation and the evolution of individual segments of the sedimentary basin are still not well known. The Miocene complex is difficult to recognize using standard seismic interpretation methods due to cumulative effects of depositional, erosional, and tectonic processes. Progress in science and technology offers new opportunities for the application of high-resolution methods of seismic data interpretation, such as seismostratigraphic interpretation, seismic facies analysis, and seismic geomorphology. The results of seismostratigraphic interpretation of the Machów Formation indicate the presence of numerous depositional sequences of varying thickness and spatial range. The interpretation enabled identification of various types of paleoenvironments, typical for both deeper basin zones (e.g., slope and basin floor fans) and coastal environments. Based on the research conducted, it was concluded that high-resolution 3D seismic data play an essential role in the detection and visualization of lithostratigraphic traps for hydrocarbons, which is important both in exploration and in determining hydrocarbon migration pathways.