Wyniki wyszukiwania - BazTech

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Badania petrograficzno-granulometryczno-facjalne utworów czerwonego spągowca w aspekcie poszukiwań złóż gazu zamkniętego (tight gas)

Ziemianin K.

Prace Naukowe Instytutu Nafty i Gazu

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2016

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nr 209 wyd. konferencyjne

607--611

PL

Utwory czerwonego spągowca, ze względu na obecne w nich złoża gazu, są od dziesięcioleci przedmiotem intensywnych badań geologicznych [1–3]. Współcześnie obszar występowania tych utworów, dotychczas kojarzony ze złożami konwencjonalnymi, budzi zainteresowanie również pod kątem złóż niekonwencjonalnych (ang. tight gas). Przeprowadzono analizy petrologiczno-granulometryczne dla ponad 400 próbek. Każda z przebadanych próbek została przypisana do jednej z 4 wyróżnionych facji: eolicznej, fluwialnej, plaji (jeziornej) oraz tzw. białego spągowca. W celu zbadania zależności pomiędzy składem mineralnym szkieletu ziarnowego, rodzajem spoiwa, porowatością, rozkładem uziarnienia a środowiskiem depozycji, przeprowadzono korelację uzyskanych danych. Otrzymane wyniki, w połączeniu z danymi petrofizycznymi, stanowią bogatą pulę informacji, które będą wsparciem w konstruowaniu cyfrowych modeli 3D.

EN

The Rotliegend sandstones are well known conventional gas reservoirs and have been a subject of an intense geological investigation for decades. Nowadays, even more attention is given to the Rotliegend sandstones as they may also be reservoirs for unconventional gas – tight gas. The petrographic and granulometric analyses were carried out for over 400 samples that have been described as sediments related to aeolian, fluvial, playa and so called “white Rotliegend” deposition systems. In order to investigate the relationships between the components of grains, cements and particle size distributions, the correlation analysis was performed. Presented results may be directly linked with petrophysical (porosity, permeability) features of analyzed rocks, which enables to create detailed, digital 3D models of the Rotliegend sediments.

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Determination of reservoir properties through the use of computed X-ray microtomography – eolian sandstone examples

Dohnalik M., Jarzyna J.

Geology, Geophysics and Environment

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2015

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Vol. 41, no. 3

223--248

EN

The possibility of examining rock pore structure by the means of computed X-ray microtomography was presented. Parameters characterizing the pore structure, such as: porosity and coefficient of homogeneity of pore structure by local porosity examination, box counting dimension, mean chord length, normalized Euler number, as well as coordination number were all determined through pore structure image analyses. Complementary methods, such as helium pycnometry, mercury injection capillary pressure and NMR were used to determine the porosity along with other factors to make the comparison and determine mutual relationships between petrophysical properties obtained from various sources. The study covered the Rotliegend sandstones of eolian origin. Laboratory investigation of the reservoir properties was focused on three areas, according to their geological regions, where the Rotliegend sediments showed changeability in geological features and reservoir properties. Computed X-ray microtomography showed differentiation between the investigated areas, with respect to their pore structure and porosity development. This differentiation was confirmed by means of other applied laboratory methods.

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Występowanie gazu ziemnego zamkniętego w piaskowcach czerwonego spągowca Polski

Kiersnowski H., Buniak A., Kuberska M., Srokowska-Okońska A.

Przegląd Geologiczny

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2010

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Vol. 58, nr 4

335-346

EN

The paper presents the first unconventional tight gas field discovered in tight low permeability (K > 0.1 mD) eolian sandstones in the Polish Upper Rotliegend Basin. The tight gas field has been found in area east of Poznań (Siekierki zone). In that area, reservoir eolian sandstones lost almost all permeability and partly porosity due to compaction and illitization processes. The origin of the gas trap was analyzed in many variants, from which one was selected as the most probable. It is assumed that main source for illite crystallization were Zechstein hypersaline brines rich in Ca, Na, K and SO4, which infiltrated the Rotliegend sandstones on tectonically uplifted block. The gas generation and migration were taking place at the same time as processes responsible for decrease in sandstone permeability have been ceasing. As a result, tight gas field from the Siekierki zone can be defined as an unconventional gas field occurring in conventional structural trap. It is expected that tight gas fields could also originate in deeper parts of the Polish Rotliegend Basin but under conditions of BCGS (Basin-Centered Gas System). Gas fields originating under this system are without classic seal and its capacity can be significantly bigger than those of conventional gas fields. The type of organic matter occurring in mature Carboniferous rocks was determining composition of gas formed at gas generation phase. It also affected the chemical content of infiltrating fluids and, in this way, had significant influence on the course of diagenetic processes. In the fault zones, diagenetic cements formed impermeable barriers which separate conventional and unconventional gas fields, as well as barriers separating individual parts of these fields. Such compartmentalization was surely important for origin of the tight gas reservoirs in the Polish Upper Rotliegend Basin.

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Ilościowa charakterystyka porowatości i przepuszczalności utworów czerwonego spągowca potencjalnie zawierających gaz ziemny zamknięty

Such P., Leśniak G., Słota M.

Przegląd Geologiczny

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2010

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Vol. 58, nr 4

345-351

EN

Withinaframe of the research project on Rotliegend tight gas, a data base comprising 760 full sets of reservoir and permeability parameters was created. Data from 55 wells were collected from interval of 1650-5003 m. The obtained results showed presence of clastic reservoirs sufficient for formation of "tight gas" type deposits in each of the analyzed wells. In most of the wells, reservoir rock series with non-zero permeability were detected. Parameters of pore space suggest the major role of compaction processes in pore space evolution, except for some areas where cementation processes were predominating. A high-permeability anomaly characterizing a separate group of eolian sandstones from the depths of over 4000 m anomaly may be explained as due to presence of pseudo- and micro-fractures.

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Variability of the Rotliegend sandstones in the Polish part of the Southern Permian Basin - permeability and porosity relationships

Jarzyna J., Puskarczyk E., Bała M., Papiernik B.

Annales Societatis Geologorum Poloniae

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2009

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Vol. 79, No 1

13-26

EN

The Flow Zone Index, FZI, applied to order relations between the effective porosity and permeability of the Rotliegend sandstones in the Polish part of the Southern Permian Basin turns out to be a useful and effective factor to evaluate ability of media flow in a rock formation. A dataset of over 2000 samples from 78 wells was analysed. Based only on porosity and permeability, FZI includes all non-parameterized features of rocks as tortuosity and diameters of porous channels, volume of trapped parts of capillary roads, specific surface of pore space, and others. When FZI increases, the ability of fluid to move through the porous space increases. In most cases, the Rotliegend sandstones reveal FZI in the range of 0.5-2.0. The highest FZI, ca. 100, is related to fractured part of the studied formation. The combination of FZI and facies information from several wells in the study area (over 1200 samples) showed a good correlation. On the basis of FZI we can divide a set of samples of the Rotliegend sandstone into groups of defined fluid flow abilities and relate them to facies. Also, we show the way of estimation of the reliable values of permeability in full geological log of a borehole on the basis of FZI, and the total porosity determined from well logging interpretation.