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1

Identification of volcanic lithofacies using box-counting method calculating fractal dimension of logging data

Mou Dan, Wang Zhuwen, Tan Xili, Shi Shaoyun

Acta Geophysica

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2022

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Vol. 70, no 6

2647--2658

EN

Identification of volcanic lithofacies is critical for reservoir exploration and a major difficulty in China's Liaohe oil field. In this paper, we present a fractal analysis method for identifying volcanic facies by estimating the fractal dimension of logging data. The fractal properties of lithofacies logging curves are explored, as well as the categorization scheme of volcanic lithofacies in the eastern sag of the Liaohe basin. Five logging curves impacted by volcanic lithofacies from four wells in the Liaohe basin's eastern depression were chosen. The Box-counting dimension is used to develop a logging lithofacies identification criterion. Furthermore, we calculated the fractal dimension of logging curves using box-counting dimension methods.

2

Fuzzy support vector regression for permeability estimation of petroleum reservoir using well logs

Moosavi Nastaran, Bagheri Majid, Majid Nabi-Bidhendi, Heidari Reza

Acta Geophysica

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2022

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Vol. 70, no 1

161--172

EN

In this paper we propose a three-step approach to predict permeability. First, by using Electrofacies Analysis (EA), data are classified into several clusters. We take advantage of EA to overcome abrupt changes of permeability which its unpredictability prevents a machine to be learned. EA is also helpful for wells that suffer from core data. Second, fuzzy membership functions are applied on data points in each Electrofacies Log (EL). Third, Support Vector Regression (SVR) is employed to predict permeability using fuzzy clustered data for areas with core missing data. To perform this process, we applied the proposed technique on four well sets of a gas field located in South of Iran; three wells devoted to training and the fourth remained for testing operation. Seven ELs derived using Multi Regression Graph-Based Clustering (MRGC) method. MRGC is able to estimate more appropriate number of clusters without prior knowledge compared to other three algorithms for our case-study area. Then, fuzzy membership functions applied to data. Thereafter, SVR applied to both fuzzy and not-fuzzy ELs. Consequently, the predicted permeability log for both fuzzy and not-fuzzy inputs correlated to real permeability (core data obtained from plugs in laboratory) in the test well. Finally, predicted permeability for each face merged together to make an estimated permeability for the whole test well. The results show that predicted permeability obtained from application of SVR on fuzzy data (FSVR) has a notably better correlation with core data for both clusters individually and the whole data compared to SVR.

3

3D pore pressure modeling and overpressure zone prediction in the upper Assam Shelf, India

Rai Neha, Singha Dip Kumar, Chatterjee Rima

Acta Geophysica

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2022

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Vol. 70, no 3

1203--1221

EN

Quantitative variation of pore pressure within the formations is essential for the selection of drilling mud, and to avoid catastrophic incidents such as blowouts. In this paper, we estimate to detect in-situ overpressure zone (OPZ) and to establish the adequate spatial distribution of PP from a 3D seismic data containing three wells in the foreland basin of the upper Assam shelf. We applied the fact that the porosity of Shale decreases monotonically as the effective stress increases, so we delimited the Shale volume up to 70% for PP estimation. The OPZ has been identified in the wells by comparing two methods: first, deviation of sonic transit time from normal compaction trend, and second, the separation between sonic-density porosity. The predicted PP is validated by repeat formation test and mud weight data. The 3D pore pressure model that obtained by velocity-effective stress transformation method matches with pore pressure in the wells with excellent goodness of ft. The PP gradient varies from 14.22 to 15.50 MPa/km in OPZ, and the top of OPZ ranges from 1225 to 2182 m, respectively. The spatial distribution of pore pressure is found to be mostly normal pressure for Barail, Sylhet and fracture basement except in the Kopili formation in which OPZ is spatially distributed, and higher pressure is observed in the locations toward the S-SE direction. Our results reveal the occurrence of overpressure zone in Barail and Kopili formations of Oligocene to Eocene, which can be attributed to the disequilibrium compaction phenomenon.

4

Zastosowanie sztucznej inteligencji w procesie klasyfikacji facji skał zbiornikowych w oparciu o dane geofizyki otworowej

Barbacki Jan

Wiadomości Naftowe i Gazownicze

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2021

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R. 24, Nr 2 (267)

4--8

PL

W artykule przedstawiono możliwość wykorzystania metod uczenia maszynowego do automatycznego wyznaczenia litofacji na podstawie danych geofizyki otworowej. Zaprezentowano zarówno podstawowe koncepcje przyświecające rozwiązaniom typu data-driven, jak również opisano schemat pracy z danymi złożowymi. Omówiono także popularne techniki klasyfikacyjne: maszynę wektorów nośnych, drzewa decyzyjne, lasy losowe oraz sztuczne sieci neuronowe. Zaproponowane rozwiązanie może okazać się niezwykle przydatne w modelowaniu złóż węglowodorów, szczególnie w przypadku braku wystarczającej ilości danych pochodzących z badań laboratoryjnych rdzeni skalnych.

EN

The paper presents the possibility of using selected machine learning methods for automatic facies determination based on well-log data. The study presents fundamental concepts of a data-driven approach, as well as presents the detailed workflow for working with reservoir data. Popular classification techniques such as support vector machine, decision trees, random forests and artificial neural networks are also discussed. The proposed methodology can prove to be extremely useful in computer modeling of hydrocarbon reservoirs, especially in the case of reduced core sample dataset.

5

Multichannel seismic impedance inversion driven by logging–seismic data

Li Xinyu, Wang Yaojun, Liu Yu, Cai Hanpeng

Acta Geophysica

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2021

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Vol. 69, no. 6

2261--2274

EN

The prior information constrained impedance inversion is an important tool to improve the inversion effect. With the traditional constrained prior information extracted from logging data by the analytic formula, it is difficult to accurately describe the information of a complex reservoir. In addition, the traditional inversion method is trace-by-trace, which ignores the lateral information contained in seismic data. This paper presents a multichannel seismic impedance inversion method combining logging and seismic. In this method, the dictionary learning method is used to extract the vertical prior information of the formation from the logging data. At the same time, we can learn the dip information from seismic data cube. Under the framework of multichannel inversion, regularization and sparse representation technology are used to simultaneously add the vertical and the transverse distribution prior information into the inversion process. Block coordinate descent method is used to solve the multichannel inversion problem, making the seismic inversion efficient. This method excavates the spatial prior information in a data-driven way and is used for constrained inversion, avoiding the false prior cognition caused by manual interpretation. Through the model and field data testing, it is verified that this method is effective.

6

Estimation of electrical resistivity using artifcial neural networks: a case study from Lublin Basin, SE Poland

Ważny Jakub, Stefaniuk Michał, Cygal Adam

Acta Geophysica

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2021

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Vol. 69, no. 2

631--642

EN

Artifcial neural networks method (ANNs) is a common estimation tool used for geophysical applications. Considering borehole data, when the need arises to supplement a missing well log interval or whole logging-ANNs provide a reliable solution. Supervised training of the network on a reliable set of borehole data values with further application of this network on unknown wells allows creation of synthetic values of missing geophysical parameters, e.g., resistivity. The main assumptions for boreholes are: representation of similar geological conditions and the use of similar techniques of well data collection. In the analyzed case, a set of Multilayer Perceptrons were trained on fve separate chronostratigraphic intervals of borehole, considered as training data. The task was to predict missing deep laterolog (LLD) logging in a borehole representing the same sequence of layers within the Lublin Basin area. Correlation between well logs data exceeded 0.8. Subsequently, magnetotelluric parametric soundings were modeled and inverted on both boreholes. Analysis showed that congenial Occam 1D models had better ftting of TM mode of MT data in each case. Ipso facto, synthetic LLD log could be considered as a basis for geophysical and geological interpretation. ANNs provided solution for supplementing datasets based on this analytical approach.

7

A comparative study of empirical, statistical, and soft computing methods coupled with feature ranking for the prediction of water saturation in a heterogeneous oil reservoir

Jahan Labiba Nusrat, Munshi Tanveer Alam, Sutradhor Sree Sujon, Hashan Mahamudul

Acta Geophysica

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2021

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Vol. 69, no. 5

1697--1715

EN

The present research applies six empirical, three statistical, and two soft computing methods to predict water saturation of an oil reservoir. The employed empirical models are ‘Archie (Trans AIME 146(1):54–62, 1942),’ ‘DeWitte (Oil Gas J 49(16):120–134, 1950),’ ‘Poupon et al. (J Petrol Technol 6(6):27–34, 1954),’ ‘Simandoux (Revue deI’Institut Francais du.Petrol, 1963),’ ‘Poupon and Leveaux (1971),’ and ‘Schlumberger (Log interpretation principles/applications, p. 235, 7th printing. Houston, 1998)’; statistical methods are ‘multiple variable regression,’ ‘fine tree, medium tree, coarse tree-based regression tree,’ and ‘bagged tree, boosted tree-based tree ensembles’; and soft computing techniques are ‘support vector machine (SVM)’ and ‘Levenberg–Marquardt (LM), Bayesian regularization (BR), and scaled conjugate gradient (SCG)- based artificial neural network (ANN).’ In addition, log variables are ranked based on their significance in water saturation modeling. To achieve the goals, 521 data points are selected from three wells. Each data point has laboratory-derived core water saturation information and six well log features, such as gamma ray (GR), bulk density (RHOB), sonic travel time (DT), true resistivity (LLD), neutron porosity (φN), and Depth. Statistical indexes, namely regression coefficient, mean squared error, root mean squared error, average absolute percentage error, minimum absolute error percentage, and maximum absolute error percentage, are used to compare the prediction efficiency of study methods. Results show that the empirical models provide exceedingly poor prediction efficiency. Within the study models, fine tree, medium tree-based regression tree; bagged tree, boosted tree-based tree ensembles; fine Gaussian SVM; ANN with LM; and ANN with BR are very efficient predictive strategies. The log ranking reveals that GR and DT are the most important, whereas RHOB and φN are the least vital predictor variables in water saturation prediction.

8

Badania geofizyki otworowej na potrzeby budowy tuneli

Roguska Emilia

Materiały Budowlane

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2020

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nr 2

5--7

PL

Geofizyka otworowa jest bardzo dynamicznie rozwijającym się narzędziem badań geologicznych. Choć wykorzystuje się ją głównie w przypadku poszukiwania złóż naturalnych, to jej metody mogą także dostarczyć wielu ważnych danych przydatnych przy budowie tuneli. W artykule omówione zostały główne grupy metod badań geofizyki otworowej oraz ich zastosowanie w rozpoznaniu geotechnicznym. Podano przykłady metod najczęściej wykorzystywanych przy badaniach geologiczno-inżynierskich oraz omówiono ich zasady.

EN

Well-logging is one of the most dynamically developing method of geological investigation. It is mainly used for the purposes of oil and gas exploration, still it brings a lot of informative data for tunnel design. The article describes the main methods of well-logging and their application in geotechnical investigation. The examples of methods used for this purpose were presented and the principles of their operation were discussed.

9

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.

10

Porównanie efektywności trzech systemów odbioru wody podziemnej ujęcia infiltracyjnego dla Bydgoszczy pod względem wydajności i energooszczędności oraz analiza ich starzenia i dobór środków zapobiegawczych

Boroń Marzena, Górka Tomasz

Biuletyn Państwowego Instytutu Geologicznego

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2019

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nr 476, Hydrogeologia z. 17

17--23

PL

Artykuł prezentuje efektywność odbioru wody na ujęciu infiltracyjnym dla Bydgoszczy studniami eksploatowanymi, pompami głębinowymi, lewarami i drenażami zbiorczymi. Opisano przebieg eksploatacji i postęp kolmatacji w zależności od konstrukcji studni z pompami, lewarowych i drenaży zbiorczych. Porównano zużycie energii elektrycznej w tych trzech metodach poboru wody infiltracyjnej. Zasięg kolmatacji rejestrowano inspekcjami TV, pomiarami w pompowaniach strefowych i metodami geofizycznymi. Po 9 latach eksploatacji można stwierdzić, że tak zaprojektowany odbiór wody obniżył koszty eksploatacji w zakresie energii i opłat środowiskowych. Obserwacje procesów kolmatacji na filtrach studziennych i odpowiednio projektowane renowacje pozwalają aktualnie utrzymać wydatek jednostkowy studni na poziomie ok. 100% z okresu budowy.

EN

The paper presents the effectiveness of an artificially recharged well field system in Bydgoszcz, consisting of pump and siphon wells plus drains. The course of exploitation and the progress in clogging, depending on the well construction (pump, siphon, or drain wells), is described. Energy consumption for these three water extraction methods are compared. The clogging range was observed by camera inspections, zone pumping tests, and geophysical methods. After nine years of exploitation, it is possible to assume that the designed system saves the energy consumption and environmental charges. Observations of clogging processes and appropriate well rehabilitations enable to maintain nearly 100% of the new well-specific capacity.

11

Well logging interpretation methodology for carbonate formation fracture system properties determination

Stadtműller Marek

Acta Geophysica

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2019

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Vol. 67, no. 6

1933--1943

EN

The article presents the methodology for the qualitative determination of fracture zones in the profiles of carbonate formations, based on the complex fracture analysis (CFA) method. Three additive fracture ranges were distinguished, characterized by successively increasing aperture and fracture length values, operatively named micro, meso and macro. Furthermore, the quantitative characterization of fractures with different apertures was done. The methodology of laboratory data integration, fracture porosity and fracture permeability measurements performed on thin section and polished section was described as part of the quantitative well logging data interpretation procedure which uses the FPI (fracture porosity index) parameter. The research was performed in the Lower Carboniferous limestone formation that builds the Paleozoic basement of the Carpathian orogeny. An original software dedicated to the analysis of the wellbore images, obtained with the XRMI Halliburton scanner, was used to identify the presence of macro-fractures, determine their aperture and estimate fractures porosity and permeability in the profile of the analyzed rock formation. As a result of the work, postulates regarding the methodology for collecting research material were formulated, in particular: the scope of different laboratory core samples measurements and well log types. The principles of the optimal methodology for identifying fractured zones and quantitative evaluation of petrophysical parameters of recognized fracture systems were defined.

12

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.

13

Estimation of absolute permeability using artificial neural networks (multilayer perceptrons) based on well logs and laboratory data from Silurian and Ordovician deposits in SE Poland

Waszkiewicz Sebastian, Krakowska-Madejska Paulina, Puskarczyk Edyta

Acta Geophysica

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2019

|

Vol. 67, no. 6

1885--1894

EN

Permeability is a property of rocks which refers to the ability of fluids to flow through each substance. It depends on several factors as pore shape and diameter. Also the presence and type of clay has a large influence on the permeability value. Permeability can be measured on rock sample in the laboratory by injecting fluid through the rock under known condition, but this provides only point information. Due to the dependence of the parameter on many factors, the deterministic estimation of permeability based on laboratory measurement and well logs is problematic. Many empirical methods for determining permeability are available in the literature and interpretation systems. An interesting approach to the problem is the use of artificial neural networks based on laboratory measurement and modern, high-resolution logging tools. The authors decided to use MLP artificial neural networks, which allow permeability estimation and can be used both in the test well and applied to neighbouring wells. The network was checked in several variants. Obtained results show the legitimacy of using artificial neural networks in the issue of estimating permeability. However, they also show limitations resulting from the lack of accurate data or influence of geological setting and processes.

14

Archival gamma ray logs standardization by nondestructive core measurements of the low‑radioactivity rocks

Skupio Rafał, Kubik Benedyk, Wolański Krzysztof

Acta Geophysica

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2019

|

Vol. 67, no. 6

1835--1844

EN

The present study analyzes spectral gamma ray data of low-radioactivity rock cores from Rotliegend Basin. The main goal of this research was standardization of archival gamma ray logs measured in counts per minute to American Petroleum Institute units. Selected core intervals, log data, and additional crushed samples covered three different boreholes: J-1, L-7, and K-2 from Zielona Góra Basin, localized in western Poland, where J-1 was a reference borehole. Core measurements were performed on the sandstone and conglomerate formations by Gamma Logger GT spectrometer, which uses two scintillation detectors containing bismuth germanate crystals. In the cores, real concentrations of potassium, uranium, and thorium were acquired what enabled to calculate total content of radioactive elements and total uninfluenced by uranium. Delivered new total GR_GLGT curve from cores allowed accurate standardization of archival GR curves from L-7 and K-2 boreholes. Presented results showed a very good correlation between logs, core data, and laboratory analyses. These data allow precise shale volume reinterpretation.

15

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

|

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.

16

Statystyczny charakter rozpadu promieniotwórczego

Zych M.

Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej

|

2017

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Nr 55

89--92

PL

Artykuł prezentuje ćwiczenie laboratoryjne i stanowisko do badania właściwości radiometrycznej sondy otworowej. Pomiary radiometryczne są obecnie istotną częścią geofizyki otworowej pozwalając na określenie wielu parametrów petrofizycznych skał jak gęstość, porowatość, itp. Stąd niezbędne jest, aby studenci kierunku Geofizyka na Wydziale Geologii, Geofizyki i Ochrony Środowiska AGH zapoznali się z podstawowymi problemami związanymi z tego typu pomiarami, na które ma wpływ rozpad promieniotwórczy (np. fluktuacje statystyczne), czy też budowa sondy geofizycznej (np. energetyczna zdolność rozdzielcza wykorzystanego detektora).

EN

This article presents a laboratory standpoint for testing the properties of a probe for radiometric measurements. Radiometric measurements are now an important part of well logging, allowing for determination of many petrophysical parameters of rocks such as density, porosity, etc. It is therefore essential that students of Geophysics at the Department of Geology, Geophysics and Environmental Protection AGH-UST find out the basic problems related to such measurements, which are affected by radioactive decay (e.g. statistical fluctuations) or the construction of a geophysical probes (e.g. the energetic resolution of the detector used).

17

Pomiar zawartości toru, uranu i potasu w próbkach z rdzeni wiertniczych

Zych M.

Przegląd Elektrotechniczny

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2017

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R. 93, nr 9

142--145

PL

Ciągły pomiar zawartości toru, uranu i potasu w otworze wiertniczym (profilowanie gamma), jak i laboratoryjne badanie próbek skalnych z wydobytych rdzeni jest jedną ze standardowych metod, które służą do rozróżniania litologii formacji skalnych. Oznaczenie Th, U i K wiąże się z szeregiem problemów, które są wynikają z innego układu geometrycznego oraz objętości i masy skały wpływających na wynik pomiaru w otworze i w laboratorium. Próbki z rdzeni wiertniczych mają masy nie przekraczające 40 g. Objętość i masa skały dostarczające informacji o formacji w czasie profilowania w otworze zależą od pionowej rozdzielczości i zasięgu radialnego sond pomiarowych. Wymienione czynniki wpływają na dokładność wyznaczenia koncentracji pierwiastków. Artykuł przedstawia metodykę pomiaru laboratoryjnego opracowaną w Katedrze Geofizyki Wydziału Geologii Geofizyki i Ochrony Środowiska AGH.

EN

Continuous measurement of thorium, uranium and potassium content in borehole (Gamma Ray log) and laboratory investigations of rock samples from the drilling cores are the standard methods used to distinguish rock formations in lithology. The is a number of problems is related to the Th, U and K determination in aspect of different borehole and laboratory geometry and volume of rock mass in investigations. Samples from drilling cores have a mass not exceeding 40 g. Volume and mass of rock providing the information in well logging depends and vertical resolution and radius of investigation of borehole devices. The mentioned factors affect the accuracy of determining the concentration of chemical elements. The article presents the methodology of measurement developed at the Department of Geophysics of the Faculty of Geology Geophysics and Environmental Protection at the AGH-UST.

18

Metody wyznaczenia porowatości ogólnej na podstawie proﬁlowań geoﬁzyki otworowej w utworach klastycznych i węglanowych

Drabina A.

Prace Instytutu Mechaniki Górotworu PAN

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2017

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T. 19, nr 2

13--24

PL

Celem przeprowadzonych badań było wyznaczenie porowatości ogólnej w utworach klastycznych i węglanowych. Do obliczenia współczynnika porowatości ogólnej wykorzystano dane z trzech profilowań geofizyki otworowej: z profilowania akustycznego, z profilowania gęstościowego oraz z profilowania neutronowego. Każde profilowanie wymagało wprowadzenia odpowiednich poprawek. Otrzymane wyniki porównano z profilowaniem referencyjnym PHI.

EN

The main goal of this project was to find total porosity in sedimentary and carbonate rocks. Data from three logs such as sonic, density and neutron log was used to calculate the total porosity. The results were corrected and compared with reference data from PHI.

19

Charakterystyka parametrów sprężystych określonych na podstawie pomiarów geofizyki otworowej i modelowań teoretycznych w wybranych formacjach w otworach basenu bałtyckiego i wierconych na szelfie

Bała M.

Nafta-Gaz

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2017

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R. 73, nr 8

558--570

PL

W niniejszej pracy zawarto wyniki badań parametrów sprężystych pomierzonych akustyczną sondą dipolową lub obliczonych na podstawie teoretycznych modeli z kilku otworów położonych w basenie bałtyckim i trzech na szelfie. Badania ograniczono do pięciu formacji, poczynając od charakterystycznego poziomu sylurskiego ogniwa mułowców wapnistych z Redy, stanowiącego reper sejsmiczny Sb, a kończąc na kambrze środkowym – poziom Paradoxides paradoxissimus (PP). Zauważono pewne podobieństwa w kształtowaniu się takich parametrów sprężystych jak: prędkości fal podłużnych i poprzecznych, modułów Younga, odkształcenia objętości i postaci – w analizowanych otworach basenu bałtyckiego i odwierconych na szelfie. Otwory te znajdują się w strefie średniej perspektywności dla ropy naftowej i kondensatu oraz dobrej dla gazu ziemnego [14]. Przedstawiona charakterystyka parametrów sprężystych może być wykorzystana w modelowaniach sejsmicznych do badania zmienności poziomów stratygraficznych i wyjaśnienia szeregu problemów pojawiających się przy zintegrowanej interpretacji danych geofizyki otworowej i sejsmicznych pól falowych. Wspomaga również ocenę skał ilastych pod kątem prognozowania zabiegów szczelinowania hydraulicznego i udostępniania węglowodorów ze skał zbiornikowych o niskich przepuszczalnościach. Skały te charakteryzują się zróżnicowaną „kruchością” (brittleness), którą można rozpatrywać w aspekcie składu mineralnego i parametrów sprężystych, takich jak współczynnik Poissona, moduł Younga, moduł odkształcenia objętości, postaci oraz stałe Lamégo.

EN

The paper shows the results of studies of elastic parameters determined on the basis of well acoustic measurements and theoretically modeled in selected boreholes located in the Baltic Basin and offshore Baltic Sea. The study was limited to five formations, starting from the characteristic level of the Silurian Reda calcareous sandstone Member, which is the seismic Sb benchmark and ending with the Middle Cambrian level Paradoxides Paradoxissimus (PP). It was noted, that there were similarities in the distribution of the elastic parameters, such as the velocity of compressed and shear waves, dynamic Young’s modulus, bulk and shear moduli in analyzed boreholes in the Baltic Basin and those drilled in the shelf. These boreholes are located in a zone of average prospects for oil and condensate and good for natural gas [14]. The presented characteristics of elastic parameters may be used in seismic modeling to study the variability of stratigraphic levels and to clarify a number of problems occurring during the integrated data interpretation of well logs and seismic wave fields. It also supports the evaluation of clay rocks for the prediction of hydraulic fracturing and the production of hydrocarbons from reservoir rocks with low permeability. Sedimentary rocks are differentiated in brittleness, which can be seen in terms of the mineral composition and elastic parameters, such as Poisson’s ratio, Young’s modulus, and bulk and shear moduli as well as Lamé’s constant.

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Numerical sensitivity test of three-electrode laterolog borehole tool

Szijártó M., Balázs L., Drahos D., Galsa A.

Acta Geophysica

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2017

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Vol. 65, no. 4

701--712

EN

Finite element numerical simulation has been carried out to investigate quantitatively the response of the three-electrode laterolog borehole tool (LL3) on radial and vertical heterogeneity of the rock. In order to calculate the apparent resistivity from the electric potential and the current discharge of the measurement electrode the probe coefficient of the LL3 tool with finite electrode extent was determined. Two independent methods, a finite element modeling and a semi-analytical solution, resulted in the probe coefficient of approx. 0.15 m with a relative deviation of 2.4% due to the different geometry, resolution and electronics of the models. It was established that LL3 is only slightly sensitive to the presence of mud when the borehole diameter is d ≤ 30 cm and the ratio of the resistivity of rock and the borehole mud is 1 ≤ Rt/Rm ≤ 1000. Vertical heterogeneity test pointed out that the layer boundaries can be localized exactly even for thin bedded layer (with a thickness of 1 m) and the presence of low-resistive borehole mud. Correction factors were suggested to decrease the biasing effect of the low-resistive borehole mud and the shoulder beds on the apparent resistivity observed by LL3. Finally, it was verified that the probe has large penetration depth with excellent vertical resolution, what explains the enduring popularity of the LL3 tool in well logging.