Silicification and mechanical stratigraphy control on flow pathways and hypogenic karst development in carbonate rocks

2021 ◽  
Author(s):  
Luca Pisani ◽  
Marco Antonellini ◽  
Francisco Hilario Bezerra ◽  
Augusto Auler ◽  
Jo De Waele
Keyword(s):  
Carbonate Rocks ◽  
Sedimentary Basins ◽  
Hydrocarbon Exploration ◽  
Northeastern Brazil ◽  
Petrophysical Properties ◽  
High Permeability ◽  
Mechanical Stratigraphy ◽  
Lithostratigraphic Units ◽  
Conduit System ◽  
Flow Pathways

<p>Fractured and karstified carbonate rocks are important targets for the hydrocarbon exploration industry as they usually represent very productive reservoirs. Most of the karst features in carbonate reservoirs are the result of rising fluid flow in deeply buried settings (i.e., hypogenic karst), whose origin and solutional efficiency are not connected to surface processes. Hypogenic conduits are often intercepted by drilling during hydrocarbon exploration, and their occurrence is sometimes associated with high-permeability horizons characterized by intense silicification. Silicification is a common diagenetic process in sedimentary basins, in which Si-rich fluids modify textures, mineralogy, and petrophysical properties of the host rock.  </p><p>We present the preliminary results of a multidisciplinary study performed in a cave developed within a mixed carbonate-siliciclastic succession of the Salitre Formation, in Northeastern Brazil (Calixto Cave). This cave offers the opportunity to study an accessible and extensive (more than 1 km long) conduit system associated with silicification. We performed a detailed stratigraphic and structural characterization of the sedimentary sequence in the cave, identifying different SiO<sub>2</sub> facies and textural associations. Furthermore, we described cave geometry and pattern by topographic and morphometric observations using terrestrial laser scanner 3D models. Petrographic observations at the optical microscope were complemented with porosity-permeability analyses on rock plugs, XRD, XRF, and SEM-EDX analyses to highlight composition and petrophysical properties of the different lithostratigraphic units in the cave.</p><p>We found that silicification and mechanical stratigraphy determined the formation of high-permeability and seal units, whose distribution was fundamental for controlling paleo-flow pathways, karstification, and the spatial-morphological organization of the resultant conduit system. Cave morphologies, evidence of silica dissolution, crystalline quartz deposits and their associated paragenesis suggest that the speleogenetic phase contributing to the main karst formation happened in deeply buried hypogenic conditions, involving rising alkaline fluids probably of hydrothermal origin.</p>

EFFECT OF MINERAL COMPOSITION OF CARBONATE ROCKS ON THEIR PETROPHYSICAL PROPERTIES

2017 ◽  
Vol 35 (1) ◽  
Author(s):  
Mábia Ruana Silva de Sena ◽  
José Agnelo Soares
Keyword(s):  
Mineral Composition ◽  
Carbonate Rocks ◽  
Carbonate Rock ◽  
Mineral Content ◽  
Northeastern Brazil ◽  
Petrophysical Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Rock Samples ◽  
Mineral Characterization

ABSTRACT. The construction of digital models from a set of x-ray tomography images of high resolution (μCT) acquired in rock samples is an innovative technique in growing use nowadays. The objectives of this study were: demonstrate the potential of this technique to quantify mineral content of 15 carbonate rock samples from northeastern Brazil, through μCT analysis; to compare the results with the analysis of X-ray diffraction (XRD); and to evaluate the effect of this mineral composition on the petrophysical properties of these rocks. The results achieved in the simulation of the mineral composition confirmed that the analyzed carbonate rock samples are mainly composed of calcite and or dolomite. In general the XRD results confirmed the mineral composition indicated by μCT, except for amorphous minerals and those with small contents (accessory minerals). The results show the content of major minerals controlling the petrophysical properties, especially grain density and elastic velocities. However, other factors which were assessed through the analysis of μCT, also significantly affected the elastic velocities: porosity, type of porosity (if intergranular or vugular) and proportion of microporosity present in the rock. Keywords: carbonates, microcomputed tomography, mineral characterization, petrophysics, x-ray diffraction. RESUMO. A construção de modelos digitais de rochas a partir de um conjunto de imagens de tomografia de raios de x de alta resolução (μCT) é uma técnica inovadora com uso crescente atualmente. Os objetivos deste estudo são demonstrar o potencial desta técnica para quantificar a composição mineral de quinze amostras de rochas carbonáticas oriundas de bacias sedimentares do nordeste brasileiro, através da análise dos dados de μCT, comparar os resultados com as análises de difração de raios x (DRX), e avaliar o efeito da composição mineral sobre as propriedades petrofísicas dessas rochas. Os resultados obtidos na simulação da composição mineral, através de μCT, indicam que as amostras são compostas principalmente por calcita e/ou dolomita. Em geral os resultados de DRX confirmaram a composição mineral indicada por μCT, exceto para minerais amorfos e para aqueles que apresentam pequenos teores (minerais acessórios). Os resultados demonstram que os minerais principais (com teores mais elevados) controlam as propriedades petrofísicas, especialmente a densidade de grãos e as velocidades elásticas. Entretanto, outros fatores, os quais foram avaliados através da análise de μCT, também afetaram de maneira significativa as velocidades elásticas: porosidade, tipo de porosidade (se intergranular ou vugular) e proporção de microporosidade presente na rocha. Palavras-chave: carbonatos, microtomografia de raios x, caracterização mineral, petrofísica, difração de raios x.

Late Wisconsinan glacial stratigraphy and history of southeastern Manitoba

1980 ◽  
Vol 17 (1) ◽  
pp. 19-35 ◽  
Author(s):  
James T. Teller ◽  
Mark M. Fenton
Keyword(s):  
Carbonate Rocks ◽  
Lacustrine Sediment ◽  
Precambrian Rock ◽  
Lake Agassiz ◽  
Rock Fragments ◽  
Lithostratigraphic Units ◽  
Stratigraphic Position ◽  
History Of ◽  
International Boundary ◽  
Late Wisconsinan

The history of Late Wisconsinan glaciation in southwestern Manitoba has been established by identifying and correlating ice-laid lithostratigraphic units in the subsurface. Five Late Wisconsinan tills are defined on the basis of their texture, mineralogic composition, and stratigraphic position. These new formations are, from youngest to oldest, Marchand, Whitemouth Lake, Roseau, Senkiw, and Whiteshell Formations.Late Wisconsinan ice first invaded southeastern Manitoba 22 000 to 24 000 years ago. This Laurentide glacier advanced from the northeast across the Precambrian Shield and deposited the sandy Whiteshell and Senkiw tills, which contain abundant Precambrian rock fragments and minerals and few Paleozoic carbonate grains. Shortly after this, Keewatin ice advanced from the northwest over Paleozoic carbonate rocks, depositing the loamy carbonate-rich Roseau Formation throughout most of the area. This ice remained over southeastern Manitoba until after 13 500 years ago, when it rapidly retreated northward with Lake Agassiz on its heels. Two brief glacial readvances occurred. The first overrode Lake Agassiz lacustrine sediment as far south as central North Dakota shortly after about 13 000 years ago. The clayey Whitemouth Lake till was deposited in southern Manitoba at this time. After a rapid retreat, the ice briefly pushed southward over southeastern Manitoba about 12 000 years ago to just south of the International Boundary. The sandy carbonate-rich Marchand Formation was deposited at this time as the ice overrode its own sandy outwash. By 11 000 years ago, ice had disappeared from southeastern Manitoba.

scholarly journals Assessing Natural Gas Versus CO2 Potential Underground Storage Sites in Greece: A Pragmatic Approach †

2022 ◽  
Vol 5 (1) ◽  
pp. 98
Author(s):  
Vagia Ioanna Makri ◽  
Spyridon Bellas ◽  
Vasilis Gaganis
Keyword(s):  
Natural Gas ◽  
Co2 Storage ◽  
Sedimentary Basins ◽  
Hydrocarbon Exploration ◽  
Greenhouse Gas Mitigation ◽  
Underground Storage ◽  
Pragmatic Approach ◽  
Increasing Demand ◽  
Salt Caverns

Although subsurface traps have been regularly explored for hydrocarbon exploration, natural gas and CO2 storage has drawn industrial attention over the past few decades, thanks to the increasing demand for energy resources and the need for greenhouse gas mitigation. With only one depleted hydrocarbon field in Greece, saline aquifers, salt caverns and sedimentary basins ought to be evaluated in furtherance of the latter. Within this study the potential of the Greek subsurface for underground storage is discussed. An overview and re-evaluation of the so-far studied areas is implemented based on the available data. Lastly, a pragmatic approach for the storage potential in Greece was created, delineating gaps and risks in the already proposed sites. Based on the above details, a case study for CO2 storage is presented, which is relevant to the West Katakolo field saline aquifer.

Lithostratigraphic and tectonic framework of Jurassic and Cretaceous Intermontane sedimentary basins of south-central British Columbia1This article is one of a series of papers published in this Special Issue on the theme of New insights in Cordilleran Intermontane geoscience: reducing exploration risk in the mountain pine beetle-affected area, British Columbia.

2011 ◽  
Vol 48 (6) ◽  
pp. 870-896 ◽  
Author(s):  
Janet Riddell
Keyword(s):  
British Columbia ◽  
Mountain Pine Beetle ◽  
Sedimentary Basins ◽  
Hydrocarbon Exploration ◽  
South Central ◽  
Technological Advances ◽  
Exploration Risk ◽  
History Of ◽  
Geophysical Imaging ◽  
Glacial Cover

The south-central Intermontane belt of British Columbia has a complex architecture comprising late Paleozoic to Mesozoic volcanic and plutonic arc magmatic suites, marine and nonmarine clastic basins, high-grade metamorphic complexes, and accretionary rocks. Jurassic and Cretaceous clastic basins within this framework contain stratigraphy with hydrocarbon potential. The geology is complicated by Cretaceous to Eocene deformation, dismemberment, and dislocation. The Eocene to Neogene history of the southern Intermontane belt is dominated by non-arc volcanism, followed by Pleistocene to Recent glaciation. The volcanic and glacial cover makes this a difficult region to explore for resources. Much recent work has involved re-evaluating the challenges that the overlying volcanic cover has historically presented to geophysical imaging of the sedimentary rocks in this region in light of technological advances in geophysical data collection and analysis. This paper summarizes the lithological and stratigraphic framework of the region, with emphasis on description of the sedimentary units that have been the targets of hydrocarbon exploration.

scholarly journals An integrated analysis of mineralogical and microstructural characteristics and petrophysical properties of carbonate rocks in the lower Indus Basin, Pakistan

2019 ◽  
Vol 11 (1) ◽  
pp. 1151-1167
Author(s):  
Waheed Ali Abro ◽  
Abdul Majeed Shar ◽  
Kun Sang Lee ◽  
Asad Ali Narejo
Keyword(s):  
Thin Section ◽  
Carbonate Rocks ◽  
Carbonate Rock ◽  
Indus Basin ◽  
Reservoir Quality ◽  
Data Sets ◽  
Petrophysical Properties ◽  
X Ray ◽  
Lower Indus Basin

Abstract Carbonate rocks are believed to be proven hydrocarbon reservoirs and are found in various basins of Pakistan including Lower Indus Basin. The carbonate rock intervals of the Jakkher Group from Paleocene to Oligocene age are distributed in south-western part of Lower Indus Basin of Pakistan. However, there are limited published petrophysical data sets on these carbonate rocks and are essential for field development and risk reduction. To fill this knowledge gap, this study is mainly established to collect the comprehensive high quality data sets on petrophysical properties of carbonate rocks along with their mineralogy and microstructure. Additionally, the study assesses the impact of diagenesis on quality of the unconventional tight carbonate resources. Experimental techniques include Scanning Electronic Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDS), and X-ray diffraction (XRD), photomicrography, Helium porosity and steady state gas permeability. Results revealed that the porosity was in range of 2.12 to 8.5% with an average value of 4.5% and the permeability was ranging from 0.013 to 5.8mD. Thin section study, SEM-EDS, and XRD analyses revealed that the samples mostly contain carbon (C), calcium (Ca), and magnesium (Mg) as dominant elemental components.The main carbonate components observed were calcite, dolomite, micrite, Ferron mud, bioclasts and intermixes of clay minerals and cementing materials. The analysis shows that: 1) the permeability and porosity cross plot, the permeability and slippage factor values cross plots appears to be scattered, which showed weaker correlation that was the reflection of carbonate rock heterogeneity. 2) The permeability and clay mineralogy cross plots have resulted in poor correlation in these carbonate samples. 3) Several diagenetic processes had influenced the quality of carbonates of Jakkher Group, such as pore dissolution, calcification, cementation, and compaction. 4) Reservoir quality was mainly affected by inter-mixing of clay, cementation, presence of micrite muds, grain compactions, and overburden stresses that all lead these carbonate reservoirs to ultra-tight reservoirs and are considered to be of very poor quality. 5) SEM and thin section observations shows incidence of micro-fractures and pore dissolution tended to improve reservoir quality.

scholarly journals Trace element geochemistry of carbonates in the Jurassic Lusitanian Basin records mineral-fluid interactions

2019 ◽  
Vol 98 ◽  
pp. 01017
Author(s):  
Mário A. Gonçalves ◽  
Maja Vuckovic ◽  
Alfonso Fiorelli ◽  
Pedro Barrulas ◽  
José Mirão
Keyword(s):  
Trace Elements ◽  
Fluid Flow ◽  
Carbonate Rocks ◽  
Sedimentary Basins ◽  
Trace Element Geochemistry ◽  
Element Geochemistry ◽  
Chemical Signatures ◽  
Icp Ms ◽  
Mineral Interaction ◽  
Lusitanian Basin

Carbonate rocks in sedimentary basins are reactive and can record complex histories of events associated with fluid flow in these basins. These include processes of dolomitization and dedolomitization. In this work we provide some preliminary data where distinct calcite and dolomite generations in the Jurassic Lusitanian Basin were analysed by LA-ICP-MS for trace elements in order to characterize chemical signatures of fluid-mineral interaction. It was observed that different carbonate generations can preserve the range of certain trace metal concentrations, but later calcites have distinctly higher contents in REE, Th and U, and Ba. Dolomites also show distinct chemical signatures but lack of analytical and spatial resolution does not allow quantification of the precursor calcite relicts. However, these processes point to the action of basinal fluids triggered by distinct tectonic episodes and associated volcanic activity.

LATERAL AND VERTICAL RANK VARIATION: IMPLICATIONS FOR HYDROCARBON EXPLORATION

1978 ◽  
Vol 18 (1) ◽  
pp. 143 ◽  
Author(s):  
A.J Kantsler ◽  
G. C. Smith ◽  
A. C. Cook
Keyword(s):  
Vitrinite Reflectance ◽  
Sedimentary Basins ◽  
Hydrocarbon Exploration ◽  
Hydrocarbon Generation ◽  
Marked Rise ◽  
Canning Basin ◽  
Early Maturation ◽  
Late Tertiary ◽  
Uplift And Erosion ◽  
Gas Fields

Vitrinite reflectance measurements are used to determine the vertical and lateral patterns of rank variation within four Australian sedimentary basins. They are also used to estimate palaeotemperatures which, in conjunction with present well temperatures, allow an appraisal of the timing of coalification and of hydrocarbon generation and distribution.The Canning Basin has a pattern of significant pre-Jurassic coalification which was interrupted by widespread uplift and erosion in the Triassic. Mesozoic and Tertiary coalification is generally weak, resulting in a pattern of rank distribution unfavourable to oil occurrence but indicating some potential for gas. The Cooper Basin also has a depositional break in the Triassic, but the post-Triassic coalification is much more significant than in the Canning Basin. The major gas fields are in, or peripheral to, areas which underwent strong, early, telemagmatic coalification whereas the oil-prone Tirrawarra area is characterized by a marked rise in temperature in the late Tertiary. The deeper parts of the Bass Basin underwent early coalification and are in the zone of oil generation, while most of the remaining area is immature. Inshore areas of the Gippsland Basin are also characterized by early coalification. Areas which are further offshore are less affected by this phase of early maturation, but underwent rapid burial and a sharp rise in temperature in the late Tertiary.

THE INTERPRETATION OF AEROMAGNETIC SURVEYS FOR HYDROCARBON EXPLORATION

1999 ◽  
Vol 39 (1) ◽  
pp. 494
Author(s):  
I. Kivior ◽  
D. Boyd
Keyword(s):  
Spectral Analysis ◽  
Sedimentary Basins ◽  
Hydrocarbon Exploration ◽  
Petroleum Exploration ◽  
Magnetic Data ◽  
Curve Matching ◽  
Aeromagnetic Data ◽  
Profile Data ◽  
Aeromagnetic Survey ◽  
New Approach

Aeromagnetic surveys have been generally regarded in petroleum exploration as a reconnaissance tool for major structures. They were used commonly in the early stages of exploration to delineate the shape and depth of the sedimentary basin by detecting the strong magnetic contrast between the sediments and the underlying metamorphic basement. Recent developments in the application of computer technology to the study of the earth's magnetic field have significantly extended the scope of aeromagnetic surveys as a tool in the exploration for hydrocarbons. In this paper the two principal methods used in the analysis and interpretation of aeromagnetic data over sedimentary basins are: 1) energy spectral analysis applied to gridded data; and, 2) automatic curve matching applied to profile data. It is important to establish the magnetic character of sedimentary and basement rocks, and to determine the regional magnetic character of the area by applying energy spectral analysis. Application of automatic curve matching to profile data can provide results from the sedimentary section and deeper parts of a basin. High quality magnetic data from an experimental aeromagnetic survey flown over part of the Eromanga/Cooper Basin has recently been interpreted using this new approach. From this survey it is possible to detect major structures such as highs and troughs in the weakly magnetic basement, as well as pick out faults, and magnetic layers in the sedimentary section. The results are consistent with interpretation from seismic and demonstrate that aeromagnetic data can be used to assist seismic interpretation, for example to interpolate between widely spaced seismic lines and sometimes to locate structures which can not be detected from seismic surveys. This new approach to the interpretation of aeromagnetic data can provide a complementary tool for hydrocarbon exploration, which is ideal for logistically difficult terrain and environmentally sensitive areas.

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