scholarly journals Origin of Micropores In Late Jurassic (Oxfordian) Micrites of the Eastern Paris Basin, France

2015 ◽  
Vol 85 (6) ◽  
pp. 660-682 ◽  
Author(s):  
Cédric Carpentier ◽  
Serge Ferry ◽  
Christophe Lécuyer ◽  
André Strasser ◽  
Yves Géraud ◽  
...  

Abstract:  Porous micritic facies, either primary chalks or resulting from secondary destructive micritization, can constitute important hydrocarbon or water reservoirs. Characterization of reservoir properties and the understanding of factors which controlled the distribution of porosity are of primary interest to evaluate the prospective reserves. Middle and late Oxfordian limestones of the eastern Paris Basin show several horizons with porosities higher than 20%. The porosity is mainly microporous and located either within secondary micritized grains or in the micritic matrix. Using SEM, cathodoluminescence, as well as confocal microscopy, stable oxygen and carbon isotope ratios, and petrophysical measurements, a scenario for the evolution of the micropores is proposed. Lime mudstones to packstones constitute the majority of the high-porosity facies (HPFs). Inner lagoonal deposits are more micritized and thus more porous than grainstones, and facies rich in leiolitic oncoids and echinoid clasts are less impacted by micritization. Micritization was responsible for an increase of the intragranular porosity in most grain types. During both eogenesis and shallow burial, mineralogical stabilization dissolved aragonitic particles and allowed precipitation of calcite rhombs. This process was probably enhanced below surfaces of subaerial exposure. During burial, Ostwald ripening allowed the growth of larger micrite crystals at the expense of smaller ones during early Berriasian and late Aptian recharges of deep aquifers when the northern margin of the basin was exposed. Overgrowths on micrite crystals were more important in intervals strongly affected by chemical compaction, which favored oversaturation of waters with respect to calcite. In low-porosity horizons (LPFs), the dense micritic texture of oncoids and the monocrystalline architecture of echinoid clasts prevented an intense micritization, while the strong chemical compaction enhanced poronecrosis. Telogenetic fracturing created new fluid pathways that favored inputs of meteoric fluid in porous micrite and allowed the continuation of Ostwald ripening during Cenozoic times. As a whole, mesogenetic inputs of waters undersaturated with respect to calcite in deep aquifers during exposure of basin margins are a more efficient process than early subaerial exposure for enhancing aggrading neomorphism and appearance of microporous micrites. Initial mineralogical heterogeneities also impact the intensity of chemical compaction and thus the stratigraphical distribution of microporous limestones.

2018 ◽  
Vol 6 (4) ◽  
pp. T1095-T1115 ◽  
Author(s):  
Niles W. Wethington ◽  
Matthew J. Pranter

The Mississippian Limestone formed through complex structural, stratigraphic, and diagenetic processes involving subsidence, tectonic uplift leading to periodic subaerial exposure, changes in ocean chemistry, variability inherent with carbonate cyclicity, as well as postdepositional alteration. These geologic complexities led to significant heterogeneity and compartmentalization within Mississippian mid-continent reservoirs, obscuring stratigraphic relationships. A novel log-based approach, called derivative trend analysis (DTA), is used to identify and correlate depositional cycles associated with five major stratigraphic zones. In the absence of abundant and complete core data, DTA serves as a rudimentary, yet informative, tool to effectively develop a sequence-stratigraphic framework. Classifying electrofacies, especially those constrained to core observations, can elucidate key relationships between depositional environments and reservoir properties, as well as provide an improved understanding of spatial heterogeneity. Three methods of electrofacies classification (artificial neural network, [Formula: see text]-means clustering, and [Formula: see text] nearest neighbor clustering) provide varying accuracies when used to create predictive lithology logs based only on the combined signatures of open-hole well logs in noncored wells. Stratigraphic models produced from the integration of these lithology logs with an interpreted stratigraphic framework reveal a relatively uniform, flat-lying basal Kinderhookian section, overlain by prograding clinoforms with internally shoaling-upward cycles of limestone, shales, and spiculites deposited during the Osagean and Meramecian stages. The sequence is capped by a high-porosity unit comprised mostly of brecciated chert associated with subaerially exposed strata underlying the sub-Pennsylvanian unconformity. Toward the south and east of the Hardtner field area, Osagean strata thin significantly and are covered by Meramecian spiculites of the Cowley Formation. Spatial porosity distributions reveal high reservoir quality deposits associated with regressive phases of third-order cycles, with the highest porosity intervals occurring up-section and toward the northeast of Hardtner field.


Energies ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 4413
Author(s):  
Weronika Kaczmarczyk ◽  
Małgorzata Słota-Valim

Combinatorial analysis of key petrophysical parameters can provide valuable information about subsurface hydrocarbon reservoirs. This is particularly important for reservoirs with unconventional rock formations that, due to the low permeability, need to be stimulated by fracturing treatment to provide fluid flow to the exploitation wellbore. In this article, based on data from unconventional shale formations (N Poland), we outline how independent sets of elastic and petrophysical parameters and other reservoir features can be co-analyzed to estimate the fracture susceptibility of shale intervals, which are characterized by a high total organic carbon (TOC) content and high porosity. These features were determined by analysis of each horizon’s elastic and mineralogical brittleness index (BI). These two variants were calculated first in 1D; integrated with the seismic data and finally compared with other parameters such as acoustic impedance, ratio of compressional and shear wave velocities, porosity, and density; and then presented and analyzed using cross plots that highlighted the key relationships between them. The overall BI trends were similar in both horizontal and vertical directions. The highest BI values were observed in the southeast of the analyzed area (Source I) and in the southeast and northwest of the area (Source II). These results can form the basis for predictive modeling of reservoir properties aiding effective reservoir exploration.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Cory J. D. Matthews ◽  
Fred J. Longstaffe ◽  
Jack W. Lawson ◽  
Steven H. Ferguson

AbstractKiller whales (Orcinus orca) are distributed widely in all oceans, although they are most common in coastal waters of temperate and high-latitude regions. The species’ distribution has not been fully described in the northwest Atlantic (NWA), where killer whales move into seasonally ice-free waters of the eastern Canadian Arctic (ECA) and occur year-round off the coast of Newfoundland and Labrador farther south. We measured stable oxygen and carbon isotope ratios in dentine phosphate (δ18OP) and structural carbonate (δ18OSC, δ13CSC) of whole teeth and annual growth layers from killer whales that stranded in the ECA (n = 11) and NWA (n = 7). Source δ18O of marine water (δ18Omarine) at location of origin was estimated from dentine δ18OPvalues, and then compared with predicted isoscape values to assign individual distributions. Dentine δ18OPvalues were also assessed against those of other known-origin North Atlantic odontocetes for spatial reference. Most ECA and NWA killer whales had mean δ18OPand estimated δ18Omarinevalues consistent with18O-depleted, high-latitude waters north of the Gulf Stream, above which a marked decrease in baseline δ18O values occurs. Several individuals, however, had relatively high values that reflected origins in18O-enriched, low-latitude waters below this boundary. Within-tooth δ18OSCranges on the order of 1–2‰ indicated interannual variation in distribution. Different distributions inferred from oxygen isotopes suggest there is not a single killer whale population distributed across the northwest Atlantic, and corroborate dietary and morphological differences of purported ecotypes in the region.


2011 ◽  
Vol 415-417 ◽  
pp. 1810-1815 ◽  
Author(s):  
Jian Bing Liu ◽  
Qiang Tang ◽  
Shen Zhou Lu ◽  
Ceng Zhang ◽  
Ming Zhong Li

When the articular cartilage defect accompanies with the subchondral bone defect, using bilayer scaffolds which can integrate with surrounding host cartilage and bone tissue respectively as the tissue engineering scaffolds will be conducive to the repair of tissue defects. This paper reports a new method for preparing bilayer scaffolds. Firstly, hydroxyapatite (HA)/silk fibroin(SF) composite porous materials which have high porosity were prepared by a isostatic compaction molding method, then it was fully immersed in silk fibroin solution, and finally SF/HA bilayer scaffolds were obtained by freeze-drying. The structure of the bilayer scaffolds were investigated through scanning electron microscopy, X-ray diffraction, Fourier transform-infrared spectroscopy, electron excitation spectroscopy and electron microprobe. The results indicated that the upper layer of SF/HA bilayer scaffolds is porous SF component, the under layer is the porous HA/SF composite component and the interface of the two layer is closely connected. Furthermore, mesenchymal stem cells from mouse bone marrow were seeded into the bilayer scaffolds and the results showed that the cells had a well adhesion and growth after culturing for 3 days.


2016 ◽  
Vol 12 (1) ◽  
pp. 14
Author(s):  
Prapti Rahayu ◽  
Witri Wahyu Lestari

<p>Metal-organic frameworks (MOFs) are porous coordination polymer containing bi-or polidentate organic linker coordinated with inorganic part, such as metal oxide cluster or metal cation as node which called as secondary building unit (SBU) to form infinite structure. Due to high porosity and surface area, good thermal stability as well as the availability of unsaturated metal center or the linker influence attracts the interaction with gases, thus MOFs have potential to be applied as hydrogen storage material. One type of MOFs that have been widely studied is [Zn<sub>4</sub>O(benzene-1,4-dicarboxylate)<sub>3</sub>], namely, MOF-5.Various synthesis method have been developed to obtain optimum results. Characterization of MOF-5 from various synthesis method such as crystallinity, capacity, stability, and quantum dot behavior of MOF-5 have been summarized in this review.</p>


Author(s):  
Oluwatoyin Khadijat Olaleye ◽  
Pius Adekunle Enikanselu ◽  
Michael Ayuk Ayuk

AbstractHydrocarbon accumulation and production within the Niger Delta Basin are controlled by varieties of geologic features guided by the depositional environment and tectonic history across the basin. In this study, multiple seismic attribute transforms were applied to three-dimensional (3D) seismic data obtained from “Reigh” Field, Onshore Niger Delta to delineate and characterize geologic features capable of harboring hydrocarbon and identifying hydrocarbon productivity areas within the field. Two (2) sand units were delineated from borehole log data and their corresponding horizons were mapped on seismic data, using appropriate check-shot data of the boreholes. Petrophysical summary of the sand units revealed that the area is characterized by high sand/shale ratio, effective porosity ranged from 16 to 36% and hydrocarbon saturation between 72 and 92%. By extracting attribute maps of coherence, instantaneous frequency, instantaneous amplitude and RMS amplitude, characterization of the sand units in terms of reservoir geomorphological features, facies distribution and hydrocarbon potential was achieved. Seismic attribute results revealed (1) characteristic patterns of varying frequency and amplitude areas, (2) major control of hydrocarbon accumulation being structural, in terms of fault, (3) prospective stratigraphic pinch-out, lenticular thick hydrocarbon sand, mounded sand deposit and barrier bar deposit. Seismic Attributes analysis together with seismic structural interpretation revealed prospective structurally high zones with high sand percentage, moderate thickness and high porosity anomaly at the center of the field. The integration of different seismic attribute transforms and results from the study has improved our understanding of mapped sand units and enhanced the delineation of drillable locations which are not recognized on conventional seismic interpretations.


2020 ◽  
Vol 21 (3) ◽  
pp. 9-18
Author(s):  
Ahmed Abdulwahhab Suhail ◽  
Mohammed H. Hafiz ◽  
Fadhil S. Kadhim

   Petrophysical characterization is the most important stage in reservoir management. The main purpose of this study is to evaluate reservoir properties and lithological identification of Nahr Umar Formation in Nasiriya oil field. The available well logs are (sonic, density, neutron, gamma-ray, SP, and resistivity logs). The petrophysical parameters such as the volume of clay, porosity, permeability, water saturation, were computed and interpreted using IP4.4 software. The lithology prediction of Nahr Umar formation was carried out by sonic -density cross plot technique. Nahr Umar Formation was divided into five units based on well logs interpretation and petrophysical Analysis: Nu-1 to Nu-5. The formation lithology is mainly composed of sandstone interlaminated with shale according to the interpretation of density, sonic, and gamma-ray logs. Interpretation of formation lithology and petrophysical parameters shows that Nu-1 is characterized by low shale content with high porosity and low water saturation whereas Nu-2 and Nu-4 consist mainly of high laminated shale with low porosity and permeability. Nu-3 is high porosity and water saturation and Nu-5 consists mainly of limestone layer that represents the water zone.


2014 ◽  
Vol 51 (8) ◽  
pp. 783-796 ◽  
Author(s):  
Simon Weides ◽  
Inga Moeck ◽  
Jacek Majorowicz ◽  
Matthias Grobe

Recent geothermal exploration indicated that the Cambrian Basal Sandstone Unit (BSU) in central Alberta could be a potential target formation for geothermal heat production, due to its depth and extent. Although several studies showed that the BSU in the shallower Western Canada Sedimentary Basin (WCSB) has good reservoir properties, almost no information exists from the deeper WCSB. This study investigated the petrography of the BSU in central Alberta with help of drill cores and thin sections from six wells. Porosity and permeability as important reservoir parameters for geothermal utilization were determined by core testing. The average porosity and permeability of the BSU is 10% and <1 × 10−14 m2, respectively. A zone of high porosity and permeability was identified in a well located in the northern part of the study area. This study presents the first published geomechanical tests of the BSU, which were obtained as input parameters for the simulation of hydraulic stimulation treatments. The BSU has a relatively high unconfined compressive strength (up to 97.7 MPa), high cohesion (up to 69.8 MPa), and a remarkably high friction coefficient (up to 1.22), despite a rather low tensile strength (<5 MPa). An average geothermal gradient of 35.6 °C/km was calculated from about 2000 temperature values. The temperature in the BSU ranges from 65 to 120 °C. Results of this study confirm that the BSU is a potential geothermal target formation, though hydraulic stimulation treatments are required to increase the permeability of the reservoir.


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