Wyniki wyszukiwania - BazTech

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Badanie ciepła radiogenicznego utworów syluru i ordowiku basenu bałtyckiego na podstawie danych geofizyki otworowej i jego relacja z materią organiczną

Bała Maria, Wawrzyniak-Guz Kamila

Nafta-Gaz

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2019

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R. 75, nr 9

515--526

PL

W artykule przedstawiono wyniki obliczeń ciepła radiogenicznego (A) wykonanych dla utworów syluru i ordowiku w otworach wiertniczych L-1, K-1, O-2, B-1 i W-1 położonych w basenie bałtyckim. Wykorzystano w tym celu pomiary geofizyki otworowej – spektrometryczne profilowanie gamma (naturalnej promieniotwórczości) oraz pomiary gamma-gamma (profilowanie gęstości objętościowej). Bardzo wysokimi wartościami ciepła radiogenicznego charakteryzowały się osady sylurskich iłowców bitumicznych ogniwa z Jantaru oraz ordowickie ilasto-mułowcowe utwory formacji z Sasina. Są to utwory uznawane za potencjalne sweet spoty z uwagi na podwyższoną zawartość materii organicznej. W obu jednostkach litostratygraficznych zaobserwowano podwyższoną naturalną promieniotwórczość oraz wyraźnie obniżoną gęstość objętościową wywołane obecnością kerogenu. Połączona analiza spektrometrycznego profilowania gamma i profilowania gęstości wykazała, że za wyższą produkcję ciepła radiogenicznego w tych jednostkach odpowiedzialna jest przede wszystkim podwyższona koncentracja uranu. Anomalnie wysokie wartości ciepła radiogenicznego zaznaczały się również w ordowickich iłowcach glaukonitowych formacji ze Słuchowa, w których stwierdzono wyraźny wzrost koncentracji potasu, toru i uranu. Należy zaznaczyć, że utwory czarnych łupków bitumicznych z Jantaru oraz iłowce i mułowce z Sasina charakteryzowały się dużą zmiennością obliczonego parametru A. W prezentowanej pracy przeanalizowano także relacje między obliczonymi wartościami ciepła radiogenicznego a: całkowitym natężeniem promieniowania gamma z pomiaru spektrometrycznego, prędkościami fal podłużnych oraz gęstością objętościową. Zależności określono dla poszczególnych jednostek litostratygraficznych syluru i ordowiku. Podobne relacje ciepła radiogenicznego z profilowaniem gamma zaobserwowano we wszystkich analizowanych otworach z wyjątkiem otworu L-1, w którym sylurskie i ordowickie formacje bogate w kerogen wykazały inną charakterystykę. Zauważono również wyraźne obniżanie się ciepła radiogenicznego ze wzrostem prędkości fal podłużnych. Szczegółowa analiza danych wykazała silne relacje między prędkością a zawartością toru i potasu, które są wskaźnikami minerałów ilastych, oraz zawartością uranu, związanego z obecnością substancji organicznej. Podobny związek pokazujący tendencję obniżania się ciepła radiogenicznego zaobserwowano dla wzrastających wartości gęstości objętościowej analizowanych utworów.

EN

The paper presents results of computations of the radioactive heat production (A) for the Silurian and Ordovician rocks in the L-1, K-1, O-2, B-1, and W-1 wells located in the Baltic Basin. For this purpose, well logging data – spectral gamma (intensity of the natural radioactivity) and gamma-gamma (bulk density) logs were used. Silurian deposits of the Jantar Bituminous Black Claystone Member and Ordovician deposits of the Sasino Claystone Formation were characterised by very high values of the radiogenic heat. These units are considered as sweet spots due to a high concentration of organic matter. Increased natural radioactivity and significantly reduced bulk densities caused by the presence of kerogen were observed in both lithostratigraphic units. A joint analysis of the spectral gamma ray log and the density logs showed that the increased radiogenic heat production in these formations was mainly caused by a higher concentration of uranium. Abnormally high values of radiogenic heat were also observed in the Ordovician glauconitic claystones of the Słuchowo Formation, where an increase in potassium, thorium, and uranium concentrations was detected. It should be noted that the deposits of the black claystones of the Jantar Member, and the claystones and mudstones of the Sasino Formations were characterised by high variability of the calculated parameter A. The presented article investigated the relationship between the calculated values of radiogenic heat and natural radioactivity, the velocity of longitudinal waves, as well as between bulk density. The relations were determined for the Silurian and Ordovician deposits. Similar relations between the radiogenic heat and the gamma ray log were observed in all wells except the L-1 well, in which Silurian and Ordovician formations rich in kerogen revealed a different characteristic. A significant decrease in radiogenic heat values was observed with the increase in P wave velocity. Detailed data analyses showed strong relationships between velocity and the content of thorium and potassium, which are the indicators of clay minerals, but also the content of uranium, which is associated with the organic matter presence. A similar relation showing a tendency of decreasing radiogenic heat was obtained for increased bulk densities of the formations.

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Rock physics modelling for determination of effective elastic properties of the lower Paleozoic shale formation, North Poland

Wawrzyniak-Guz Kamila

Acta Geophysica

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2019

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Vol. 67, no. 6

1967--1989

EN

This paper presents an application of rock physics templates constructed with the use of the granular effective medium theory and the shale model to estimate the elastic properties of the Silurian and Ordovician shale formations from the Baltic Basic, Poland. The author uses available logging data from three nearby wells and their petrophysical interpretation to distinguish various lithologies and to determine average matrix mineral composition of each lithology group, essential in further rock physics modelling. Anisotropy estimation and investigation of the relation between various petrophysical parameters precede the rock physics modelling. The logging data cross-plotted in Vp/Vs/ ratio–acoustic impedance domain reveals distinct compaction trend for shales, which is not followed by shales with increased organic matter and calcareous deposits. These two lithology groups present own trends, which are related to increasing kerogen and carbonate minerals contents, respectively. The trends are the subject of rock physics modelling. Granular effective medium rock physics templates are constructed for each lithology group. The rock physics analyses reveal that the elastic properties of strongly compacted shales, including shales with organic matter, might be successfully described by the lower modified Hashin–Shtrikman bound, which is useful in compaction trend modelling. Marly deposits can be modelled in a similar way to shales. The upper modified Hashin– Shtrikman bound provides a better template for carbonates as it models the cementation process. The shale model provides independent rock physics template for shales. Comparison of these two approaches shows that the granular effective medium method better describes the elastic properties of the analysed formations. The paper includes also the proposition of the final rock physics template constructed for the Silurian and the Ordovician formation from the Baltic Basin that can contribute to a better understanding of the elastic properties of the lower Paleozoic shale plays in Poland.

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Improved recognition of rock formation on the basis of well logging and laboratory experiments results using factor analysis

Puskarczyk Edyta, Jarzyna Jadwiga A., Wawrzyniak-Guz Kamila, Krakowska Paulina I., Zych Marcin

Acta Geophysica

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2019

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Vol. 67, no. 6

1809--1822

EN

Several data sets from the Silurian and Ordovician formations from three wells on the shore of Baltic Basin in Northern Poland prepared on the basis of well logging data and results of their comprehensive interpretation were used in factor analysis. The goal of statistical analysis was structure recognition of data and proper selection of parameters to limit the number of variables in study. The top priority of research was recognition of specific features of claystone/mudstone formations predisposing them to be potential shale gas deposits. The identified data scheme based on data from one well, was then applied to: 1) well 2 and well 3 separately, 2) combined data from three wells, 3) depth intervals treated as sweet spots, i.e., formations of high hydrocarbon potential. Numbers of samples from well logging were proportional to number of laboratory data from individual formations. The extended data set comprising all available log samples in explored formations was also prepared. Outcomes from standard (Triple Combo—natural gamma log, resistivity log, neutron log and bulk density log and Quad Combo—with addition of sonic log and spectral gamma log) and sophisticated (GEM™—Elemental Analysis Tool, Wave Sonic and Nuclear Magnetic Resonance—NMR) logs were the basis for data sets. Finally, laboratory data set of huge amount of variables from elemental, mineralogical, geochemical and petrophysical laboratory experiments was built and verified in FA to select the most informative components. Conclusions on the data set size, number of factors and type of variables were drawn.

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An iterative inversion of Dual Induction Tool logs from thin-bedded Sandy-shaly formations of the Carpathian Foredeep using a modified simulated annealing method

Wilkosz Michał, Wawrzyniak-Guz Kamila

Acta Geophysica

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2019

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Vol. 67, no. 6

1865--1873

EN

In thin-bedded sandy–shaly Miocene formations of the Carpathian Foredeep, the main source of errors in gas saturation evaluation is the underestimation of resistivity of thin, hydrocarbon-bearing beds, which is the result of the low vertical resolution of induction logging tools. This problem is especially visible in older boreholes drilled in times where the Dual Induction Tool (DIT) was the primary induction tool used for determining the formation resistivity, and in shallowest depth intervals of newer boreholes where the DIT was used instead of newer array tools for cost-saving reasons. In this paper, we show how a global inversion algorithm was used to improve the vertical resolution of DIT logs. Our implementation of an iterative inversion utilizes a one-dimensional formation model, vertical response functions of the DIT, and a modified simulated annealing algorithm to determine the true vertical distribution of the formation resistivity. The algorithm was tested on resistivity logs recorded in a borehole drilled in the Carpathian Foredeep in Poland, where the DIT and the High-Resolution Array Induction (HRAI) tool were run in the same depth interval.