scholarly journals Stylolite in Upper Cretaceous Carbonate Reservoirs from Northwestern Iraq

2021 ◽  
Author(s):  
Ali Al-Juboury ◽  
Mohammed A. Al-Haj ◽  
Aboosh H. Al-Hadidy
Keyword(s):  
Upper Cretaceous ◽  
Compaction Pressure ◽  
Carbonate Reservoirs ◽  
Thickness Reduction ◽  
Pressure Solution ◽  
Upward Movement ◽  
Thin Sections ◽  
The Core ◽  
Core Samples ◽  
Mineralization Processes

Stylolites are commonly observed in the carbonate reservoirs in various oilfield of Iraq including those of upper Cretaceous successions from northwestern Iraq, where they are characterized by stylolite-rich zones in the Cenomanian-early Turonian Gir Bir Formation and to a lesser extent in the Turonian-Santonian Wajna and early Campanian Mushorah formations respectively. The observed stylolites are either large to be identified in the core samples or smaller ones that are well observed in the thin sections and are characterized by variations in amplitude, morphology and accumulated insoluble residues. The recorded stylolites are classified as hummocky, irregular, low and high-amplitudes peaks, and irregular anastomosing stylolites. Stylolites affect the porosity permeability and thickness reduction compaction as the main chemical compaction (pressure solution) that reduce porosity. Whereas, in other places, the stylolites act as seals and stop the upward movement of hydrocarbons. This is also seen for mineralization processes such as silicification that ended near the stylolite surfaces.

Fossil diatoms from the Volga Delta Holocene sediments (Damchik region) as indicators of the paleoecological conditions of sedimentation

2019 ◽  
pp. 270-273
Author(s):  
Yelena I. Shtyrkova ◽  
Yelena I. Polyakova
Keyword(s):  
Nature Reserve ◽  
Diatom Analysis ◽  
Volga Delta ◽  
The Core ◽  
Core Samples ◽  
Holocene Sediments ◽  
Fossil Diatoms

The results of fossil diatoms investigation from the deltaic sediments are presented. Samples were obtained from the core DM-1 and two Holocene outcrops from the Damchik region of the Astrakhan Nature Reserve. In the core samples eight periods of sedimentation based on diatom analysis were identified: the sediments formed in shallow freshwater basins and deltaic channels. The samples from the outcrops were investigated in much greater detail.

Using Logging and Seismic Data to Identify Boundaries Between Different OWC Units in a Deepwater Carbonate Reservoirs

2021 ◽  
Author(s):  
Kangxu Ren ◽  
Junfeng Zhao ◽  
Jian Zhao ◽  
Xilong Sun
Keyword(s):  
Seismic Data ◽  
Carbonate Rocks ◽  
Carbonate Reservoir ◽  
Carbonate Reservoirs ◽  
Sedimentary Process ◽  
Core Samples ◽  
Tight Carbonate ◽  
Porosity And Permeability ◽  
Seismic Sections ◽  
Parameters Inversion

Abstract At least three very different oil-water contacts (OWC) encountered in the deepwater, huge anticline, pre-salt carbonate reservoirs of X oilfield, Santos Basin, Brazil. The boundaries identification between different OWC units was very important to help calculating the reserves in place, which was the core factor for the development campaign. Based on analysis of wells pressure interference testing data, and interpretation of tight intervals in boreholes, predicating the pre-salt distribution of igneous rocks, intrusion baked aureoles, the silicification and the high GR carbonate rocks, the viewpoint of boundaries developed between different OWC sub-units in the lower parts of this complex carbonate reservoirs had been better understood. Core samples, logging curves, including conventional logging and other special types such as NMR, UBI and ECS, as well as the multi-parameters inversion seismic data, were adopted to confirm the tight intervals in boreholes and to predicate the possible divided boundaries between wells. In the X oilfield, hundreds of meters pre-salt carbonate reservoir had been confirmed to be laterally connected, i.e., the connected intervals including almost the whole Barra Velha Formation and/or the main parts of the Itapema Formation. However, in the middle and/or the lower sections of pre-salt target layers, the situation changed because there developed many complicated tight bodies, which were formed by intrusive diabase dykes and/or sills and the tight carbonate rocks. Many pre-salt inner-layers diabases in X oilfield had very low porosity and permeability. The tight carbonate rocks mostly developed either during early sedimentary process or by latter intrusion metamorphism and/or silicification. Tight bodies were firstly identified in drilled wells with the help of core samples and logging curves. Then, the continuous boundary were discerned on inversion seismic sections marked by wells. This paper showed the idea of coupling the different OWC units in a deepwater pre-salt carbonate play with complicated tight bodies. With the marking of wells, spatial distributions of tight layers were successfully discerned and predicated on inversion seismic sections.

Enhanced and Rock Typing-Based Reservoir Characterization of the Palaeocene Harash Carbonate Reservoir-Zelten Field-Sirte Basin-Libya

2021 ◽  
Author(s):  
Mohamed Masoud ◽  
W. Scott Meddaugh ◽  
Masoud Eljaroshi ◽  
Khaled Elghanduri
Keyword(s):  
Rock Type ◽  
Carbonate Reservoir ◽  
Classification Model ◽  
Reservoir Rocks ◽  
The Core ◽  
Core Samples ◽  
Rock Types ◽  
Rock Typing ◽  
Open Hole ◽  
Type Classification

Abstract The Harash Formation was previously known as the Ruaga A and is considered to be one of the most productive reservoirs in the Zelten field in terms of reservoir quality, areal extent, and hydrocarbon quantity. To date, nearly 70 wells were drilled targeting the Harash reservoir. A few wells initially naturally produced but most had to be stimulated which reflected the field drilling and development plan. The Harash reservoir rock typing identification was essential in understanding the reservoir geology implementation of reservoir development drilling program, the construction of representative reservoir models, hydrocarbons volumetric calculations, and historical pressure-production matching in the flow modelling processes. The objectives of this study are to predict the permeability at un-cored wells and unsampled locations, to classify the reservoir rocks into main rock typing, and to build robust reservoir properties models in which static petrophysical properties and fluid properties are assigned for identified rock type and assessed the existed vertical and lateral heterogeneity within the Palaeocene Harash carbonate reservoir. Initially, an objective-based workflow was developed by generating a training dataset from open hole logs and core samples which were conventionally and specially analyzed of six wells. The developed dataset was used to predict permeability at cored wells through a K-mod model that applies Neural Network Analysis (NNA) and Declustring (DC) algorithms to generate representative permeability and electro-facies. Equal statistical weights were given to log responses without analytical supervision taking into account the significant log response variations. The core data was grouped on petrophysical basis to compute pore throat size aiming at deriving and enlarging the interpretation process from the core to log domain using Indexation and Probabilities of Self-Organized Maps (IPSOM) classification model to develop a reliable representation of rock type classification at the well scale. Permeability and rock typing derived from the open-hole logs and core samples analysis are the main K-mod and IPSOM classification model outputs. The results were propagated to more than 70 un-cored wells. Rock typing techniques were also conducted to classify the Harash reservoir rocks in a consistent manner. Depositional rock typing using a stratigraphic modified Lorenz plot and electro-facies suggest three different rock types that are probably linked to three flow zones. The defined rock types are dominated by specifc reservoir parameters. Electro-facies enables subdivision of the formation into petrophysical groups in which properties were assigned to and were characterized by dynamic behavior and the rock-fluid interaction. Capillary pressure and relative permeability data proved the complexity in rock capillarity. Subsequently, Swc is really rock typing dependent. The use of a consistent representative petrophysical rock type classification led to a significant improvement of geological and flow models.

scholarly journals Study on the Effect of High-Temperature Heat Treatment on the Microscopic Pore Structure and Mechanical Properties of Tight Sandstone

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Liangbin Dou ◽  
Guanli Shu ◽  
Hui Gao ◽  
Jinqing Bao ◽  
Rui Wang
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Pore Structure ◽  
Water Cooling ◽  
Tight Sandstone ◽  
The Core ◽  
Core Samples ◽  
High Temperature Heat Treatment ◽  
Different Temperatures ◽  
Cooling Methods

The investigation of changes in physical properties, mechanical properties, and microscopic pore structure characteristics of tight sandstone after high-temperature heat treatment provides a theoretical basis for plugging removal and stimulation techniques, such as high energy gas fracturing and explosive fracturing. In this study, core samples, taken from tight sandstone reservoirs of the Yanchang Formation in the Ordos Basin, were first heated to different temperatures (25-800°C) and then cooled separately by two distinct cooling methods—synthetic formation water cooling and natural cooling. The variations of wave velocity, permeability, tensile strength, uniaxial compressive strength, and microscopic pore structure of the core samples were analyzed. Experimental results demonstrate that, with the rise of heat treatment temperature, the wave velocity and tensile strength of tight sandstone decrease nonlinearly, yet its permeability increases nonlinearly. The tight sandstone’s peak strength and elastic modulus exhibit a trend of the first climbing and then declining sharply with increasing temperature. After being treated by heat at different temperatures, the number of small pores varies little, but the number of large pores increases obviously. Compared to natural cooling, the values of physical and mechanical properties of core samples treated by synthetic formation water cooling are apparently smaller, whereas the size and number of pores are greater. It can be explained that water cooling brings about a dramatic reduction of tight sandstone’s surface temperature, generating additional thermal stress and intensifying internal damage to the core. For different cooling methods, the higher the core temperature before cooling, the greater the thermal stress and the degree of damage caused during the cooling process. By taking into consideration of changes in physical properties, mechanical properties, and microscopic pore structure characteristics, the threshold temperature of tight sandstone is estimated in the range of 400-600°C.

scholarly journals The two major membrane skeletal proteins (articulins) of Euglena gracilis define a novel class of cytoskeletal proteins.

1992 ◽  
Vol 118 (6) ◽  
pp. 1465-1475 ◽  
Author(s):  
J A Marrs ◽  
G B Bouck
Keyword(s):  
Amino Acid ◽  
Fusion Protein ◽  
Euglena Gracilis ◽  
Cytoskeletal Proteins ◽  
Cdna Clones ◽  
Thin Sections ◽  
Core Domain ◽  
The Core ◽  
Amino Acid Repeats ◽  
Peptide Maps

60% of the peripheral membrane skeleton of Euglena gracilis consists of equimolar amounts of two proteins (articulins) with M(r)s in SDS gels of 80 and 86 kD. To understand eventually how these proteins assemble and function in maintaining cell form and membrane integrity we have undertaken a molecular characterization of articulins. A lambda gt11 expression library constructed from Euglena gracilis mRNAs was screened with antibodies against both articulins. Two sets of cDNAs were recovered, and evidence from three independent assays confirmed that both sets encoded articulins: (a) Anti-articulin antibodies recognized a high molecular weight beta-galactosidase (beta-gal) fusion protein expressed in bacteria infected with lambda gt11 cDNA clones. (b) Antibodies generated against the bacterially expressed beta-gal fusion protein identified one or the other articulin in Western blots of Euglena proteins. These antibodies also localized to the membrane skeletal region in thin sections of Euglena. (c) Peptide maps of the beta-gal fusion protein were similar to peptide maps of Euglena articulins. From the nucleotide sequence of the two sets of cDNAs an open reading frame for each articulin was deduced. In addition to 37% amino acid identity and overall structural similarity, both articulins exhibited a long core domain consisting of over 30 12-amino acid repeats with the consensus VPVPV--V--. Homology plots comparing the same or different articulins revealed larger, less regular repeats in the core domain that coincided with predicted turns in extended beta-sheets. Outside the core domain a short hydrophobic region containing four seven-amino acid repeats (consensus: APVTYGA) was identified near the carboxy terminus of the 80-kD articulin, but near the amino terminus of the 86-kD articulin. No extensive sequence similarities were found between articulins and other protein sequences in various databanks. We conclude that the two articulins are related members of a new class of membrane cytoskeletal proteins.

Environmental Scanning Electron Microscopy Technique to Identify Asbestos Phases Inside Ferruginous Bodies

2013 ◽  
Vol 19 (2) ◽  
pp. 420-424 ◽  
Author(s):  
Alessandro Croce ◽  
Maya Musa ◽  
Mario Allegrina ◽  
Paolo Trivero ◽  
Caterina Rinaudo
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Chemical Elements ◽  
Environmental Scanning Electron Microscopy ◽  
Environmental Scanning ◽  
Thin Sections ◽  
The Core ◽  
Microscopy Technique ◽  
Ferruginous Bodies ◽  
Scanning Electron

AbstractFerruginous bodies observed in lungs of patients affected by mesothelioma, asbestosis, and pulmonary carcinoma are important to relate the illness to exposure, environmental or occupational, to asbestos. Identification of the inorganic phase constituting the core of the ferruginous bodies, formed around asbestos but also around phases different from asbestos, is essential for legal purposes. Environmental scanning electron microscopy/energy dispersive spectroscopy was used to identify the fibrous mineral phase in the core of ferruginous bodies observed directly in thin sections of tissue, without digestion of the biological matrix. Spectra were taken with sequential analyses along a line crossing the core of the ferruginous bodies. By comparing the spectra taken near to and far from the core, the chemical elements that make up the core could be identified.

Pattern of Incorporation of [3H]Uridine into RNA of Amphibian Oocyte Nucleoli

1967 ◽  
Vol 2 (2) ◽  
pp. 145-150
Author(s):  
H. C. MACGREGOR
Keyword(s):  
Nuclear Envelope ◽  
Incubation Time ◽  
Core Material ◽  
Distinct Component ◽  
Thin Sections ◽  
The Core ◽  
Amphibian Oocyte ◽  
Nucleolar Rna ◽  
Silver Grains

Amphibian oocytes were incubated in vitro in the presence of [3H]uridine, and autoradiographs were made of nucleoli isolated from these oocytes and of sections of oocytes. After incubations of 2 h or less the nucleoli of oocytes larger than 0.6 mm diameter are asymmetrically labelled. With longer incubations nucleoli from oocytes of 0.6 to 1.1 mm diameter become more uniformly labelled. Those of oocytes larger than 1.2 mm diameter remain asymmetrically labelled whatever the incubation time. Autoradiographs of 1-µ sections through oocytes larger than 0.6 mm diameter show, after short incubations, asymmetrically labelled nucleoli. In these autoradiographs silver grains are concentrated over a distinct component of each nucleolus which is eccentrically placed towards the nuclear envelope. Thin sections of oocytes show nucleoli consisting of core and cortex. The core material is always concentrated into the half of the nucleolus which lies nearer the nuclear envelope. Autoradiographs of separated nucleolar cores and cortices from oocytes larger than 0.6 mm diameter show, after short incubations, silver grains over cores but not over cortices. Similar autoradiographs prepared from oocytes of 0.6 to 1.1 mm diameter, after longer incubations, show grains over cores and cortices. These results appear to indicate that nucleolar RNA is synthesized in the nucleolar core, in association with the nucleolar DNA, and is thence transferred to the cortex where it is built into ribonucleoprotein particles. Initial asymmetrical labelling is a consequence of the eccentric location of the nucleolar core. The nucleoli of oocytes smaller than 0.6 mm diameter always label symmetrically; such nucleoli consist entirely of core material. It is suggested that the nucleoli of oocytes larger than 1.2 mm diameter always label asymmetrically because transfer of RNA from core to cortex proceeds more slowly than in smaller oocytes.

scholarly journals TAPHONOMIC ASPECTS OF VERTEBRATE FOSSILS FROM BAURU GROUP, UPPER CRETACEOUS, BRAZIL

2013 ◽  
Vol 69 ◽  
Author(s):  
Karine Lohmann Azevedo ◽  
Cristina Silveira Vega ◽  
Luiz Alberto Fernandes
Keyword(s):  
Upper Cretaceous ◽  
Bone Structure ◽  
Minas Gerais ◽  
Sao Paulo ◽  
Field Trips ◽  
São Paulo ◽  
Class Iii ◽  
Mato Grosso ◽  
Thin Sections ◽  
Osseous Structure

The Bauru Basin covers an area of about 370.000 km2, occurring in São Paulo, Paraná, Mato Grosso, Mato Grosso do Sul, Minas Gerais and Goiás states in Brazil, and also in the northeast of Paraguay. These upper Cretaceous sequence correspond to a semi-arid to arid climate and is divided in two groups, Bauru and Caiuá. The first one has the major record of fossils, being the focus of the taphonomic study. Field trips to Marília and Monte Alto municipalities (São Paulo State) and also to Uberaba city (Minas Gerais State) were made to check the depositional context and collect fossiliferous material. Vertebrate collections were visited, as the Museu de Paleontologia from Marília and Monte Alto (SP), Museu de Paleontologia da Universidade de São Paulo, as well as Museu dos Dinossauros, Centro de Pesquisas Paleontológicas Llewellyn Ivor Price from Peirópolis (MG). Four biostratinomic classes related to articulated/disarticulated fossils were identified in Vale do Rio Peixe, Uberaba, Marília, São José do Rio Preto and Presidente Prudente formations. Class I represents articulated and almost complete specimens, corresponding mainly to turtles and crocodiles. Class II comprises partially articulated specimens of skull and jaw fossils, or sequences of vertebrae. Classes I and II were recorded in Vale do Rio do Peixe, Marília (Serra da Galga Member) and Presidente Prudente formations. Class III is represented by isolated bones, and Class IV by fragmented bones. These two last classes appear in all units of the basin. For diagenetic analysis, 19 thin sections were made showing that, in general, the bone structure is well preserved, with spatic calcite filling the bone and the presence of the original phosphatic material. Marília Formation, on Echaporã Member, is the most different unit of the basin, being more carbonatic. The study of thin sections, considering the osseous structure and the biostratinomic analysis, match with the paleoenvironmental contextualization.

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