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Relevant bibliographies by topics / Nuclear pore complex inheritance

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Academic literature on the topic 'Nuclear pore complex inheritance'

Author: Grafiati

Published: 4 June 2021

Last updated: 5 February 2022

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Journal articles on the topic "Nuclear pore complex inheritance"

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Lusk, C. Patrick, and Paolo Colombi. "Toward a consensus on the mechanism of nuclear pore complex inheritance." Nucleus 5, no. 2 (February 25, 2014): 97–102. http://dx.doi.org/10.4161/nucl.28314.

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Suresh, Subbulakshmi, Sarine Markossian, Aysha H. Osmani, and Stephen A. Osmani. "Mitotic nuclear pore complex segregation involves Nup2 in Aspergillus nidulans." Journal of Cell Biology 216, no. 9 (July 26, 2017): 2813–26. http://dx.doi.org/10.1083/jcb.201610019.

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Transport through nuclear pore complexes (NPCs) during interphase is facilitated by the nucleoporin Nup2 via its importin α– and Ran-binding domains. However, Aspergillus nidulans and vertebrate Nup2 also locate to chromatin during mitosis, suggestive of mitotic functions. In this study, we report that Nup2 is required for mitotic NPC inheritance in A. nidulans. Interestingly, the role of Nup2 during mitotic NPC segregation is independent of its importin α– and Ran-binding domains but relies on a central targeting domain that is necessary for localization and viability. To test whether mitotic chromatin-associated Nup2 might function to bridge NPCs with chromatin during segregation, we provided an artificial link between NPCs and chromatin via Nup133 and histone H1. Using this approach, we bypassed the requirement of Nup2 for NPC segregation. This indicates that A. nidulans cells ensure accurate mitotic NPC segregation to daughter nuclei by linking mitotic DNA and NPC segregation via the mitotic specific chromatin association of Nup2.

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Schuldt, Alison. "Nuclear pore inheritance." Nature Reviews Molecular Cell Biology 14, no. 12 (November 22, 2013): 753. http://dx.doi.org/10.1038/nrm3714.

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Panté, N., and U. Aebi. "The nuclear pore complex." Journal of Cell Biology 122, no. 5 (September 1, 1993): 977–84. http://dx.doi.org/10.1083/jcb.122.5.977.

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Woodward, Cora L., and Samson A. Chow. "The nuclear pore complex." Nucleus 1, no. 1 (January 2010): 18–22. http://dx.doi.org/10.4161/nucl.1.1.10571.

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Davis, Laura I. "The Nuclear Pore Complex." Annual Review of Biochemistry 64, no. 1 (June 1995): 865–96. http://dx.doi.org/10.1146/annurev.bi.64.070195.004245.

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Hurt, Eduard C. "The nuclear pore complex." FEBS Letters 325, no. 1-2 (June 28, 1993): 76–80. http://dx.doi.org/10.1016/0014-5793(93)81417-x.

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Panté, Nelly. "Nuclear Pore Complex Structure." Developmental Cell 7, no. 6 (December 2004): 780–81. http://dx.doi.org/10.1016/j.devcel.2004.11.010.

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Fernandez-Martinez, Javier, and Michael P. Rout. "Nuclear pore complex biogenesis." Current Opinion in Cell Biology 21, no. 4 (August 2009): 603–12. http://dx.doi.org/10.1016/j.ceb.2009.05.001.

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Akey, Christopher W. "The nuclear pore complex." Current Biology 2, no. 5 (May 1992): 258. http://dx.doi.org/10.1016/0960-9822(92)90377-m.

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Dissertations / Theses on the topic "Nuclear pore complex inheritance"

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Suresh, Subbulakshmi. "Nup2: A multifunctional player in nuclear transport and mitotic nuclear pore complex inheritance." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1480153558155228.

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Anderson, Daniel J. "Dynamics of nuclear envelope and nuclear pore complex formation." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2008. http://wwwlib.umi.com/cr/ucsd/fullcit?p3336561.

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Thesis (Ph. D.)--University of California, San Diego, 2008.
Title from first page of PDF file (viewed December 16, 2008). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 127-145).

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Onischenko, Evgeny. "Disassembly and reassembly of the nuclear pore complex /." Stockholm, 2006. http://diss.kib.ki.se/2006/91-7140-929-7/.

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Osmanovic, D. "Polymer theory applied to the nuclear pore complex." Thesis, University College London (University of London), 2014. http://discovery.ucl.ac.uk/1451621/.

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Physically interesting behaviour can arise when soft matter is confined to nanoscale dimensions. A highly relevant biological example of such a phenomenon is the Nuclear Pore Complex (NPC), found perforating the Nuclear Envelope of all eukaryotic cells. In the central conduit of the NPC, of 30-60 nm diameter, a disordered arrangement of proteins regulates all macromolecular transport between the nucleus and the cytoplasm. Its selectivity for larger macromolecules relies on changes in a permeability barrier that is formed by these unstructured proteins, induced by interactions of these proteins with molecules called Nuclear Transport Receptors (NTRs), which can chaperone larger macromolecules through the NPC. The exact mechanism for the transport selectivity is unknown. To model these unstructured proteins in the nanoscale channel of the NPC, a density functional theory approach is developed that treats the proteins as interacting polymers. This new method is tested against Monte Carlo to show its validity. A detailed comparison between this model system and those previously proposed in the literature is provided. In a parameter range relevant for the NPC, the system shows bimodal behaviour The polymers can alternate between two condensed states: An open state, in which this condensation takes place at the channel wall, and a closed state in which it occurs at the channel centre. We then extend this model by including explicitly the effect of Nuclear Transport Receptors on the conformations of the polymers. The model takes into account the finite size of the transport receptors relative to the NPC diameter. Mapping the polymer and transport receptor behaviour over a set of physiologically relevant parameters gives different structural scenarios for the various hypothesized transport mechanisms. Further to this, the transport rates for each parameter set can be obtained, showing whether such parameters are consistent with experimental evidence. In addition to this, we study the effect of relaxing some of the assumptions of our model, specifically by looking at azimuthal symmetry breaking effects in two dimensions. We also compare our model to experimental results measuring the thickness of planar polymer brushes comprised of NPC proteins to further justify parameter choices.

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Talamas, Jessica Arielle. "Cell cycle dependent differences in nuclear pore complex assembly." Diss., [La Jolla] : University of California, San Diego, 2010. http://wwwlib.umi.com/cr/ucsd/fullcit?p3403712.

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Thesis (Ph. D.)--University of California, San Diego, 2010.
Title from first page of PDF file (viewed June 1, 2010). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (leaves 90-98).

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Stanley, George. "Probing the transport barrier of the nuclear pore complex." Thesis, University College London (University of London), 2018. http://discovery.ucl.ac.uk/10061418/.

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The nuclear pore complex (NPC) is the selective gateway through which macromolecules must pass when entering or exiting the nucleus. It is a cog in the gene expression pathway, an entrance to the nucleus exploited by viruses, and a highly-tuned nanoscale filter. The NPC is a large proteinaceous assembly with a central channel occluded by natively disordered proteins, known as FG-nucleoporins (or FG-nups). These FG-nups, along with a family of soluble proteins (known as nuclear transport receptors, or NTRs), form the selective transport barrier. Although much is known about the transport cycle and the necessity of NTRs for chaperoning cargo molecules through the NPC, the mechanism by which NTRs and NTR•cargo complexes translocate the selective transport barrier is not well understood. How can intrinsically disordered FG-nups and soluble NTRs form a transport barrier that is selective, ATP-free, and fast? In this thesis, high-resolution atomic force microscopy (AFM) and a new, fast force-spectroscopy technique (PeakForce QNM) are used to provide a structural and nanomechanical analysis of individual NPCs. This data highlights the structural diversity and complexity at the nuclear envelope, showing the interplay between the lamina network, actin filaments, and the NPCs. It reveals the dynamic behaviour of NPC scaffolds and displays pores of varying sizes. Of functional importance, the NPC central channel shows large structural diversity (in both its mechanical properties and topography), supporting the notion that FG-nup cohesiveness is in a range that facilitates collective rearrangements at little energetic cost. Furthermore, various NTRs are shown to interact in qualitatively different ways with the FG-nups, with particularly strong binding of importin-β. Next, a method for analysing the dynamics of reconstituted FG-nups inside mimetic NPCs is presented - with the results highlighting the surprisingly slow time-scale for collective rearrangement of FG-nup morphologies in the pore geometry. When this analysis is applied to the real NPC, however, no dynamic movement of FG-nups is detected. Finally, preliminary results from AFM imaging experiments of large cargoes (in this case, the hepatitis B virus capsid) translocating the NPC, are presented. This thesis supports the notion that FG-nup cohesiveness is tuned such that the energetics of stable FG-nup morphologies lie near transition states, thereby allowing the collective rearrangement of FG-nups at little energetic cost. Furthermore, it suggests that NTRs with several FG-nup binding sites (such as importin-β) are an intrinsic component of the transport barrier.

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Kelich, Joseph M. "Single-Molecule Studies on Nuclear Pore Complex Structure and Function." Diss., Temple University Libraries, 2018. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/511772.

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Biology
Ph.D.
Nuclear pore complexes (NPCs) are large macromolecular gateways embedded in the nuclear envelope of Eukaryotic cells that serve to regulate bi-directional trafficking of particles to and from the nucleus. NPCs have been described as creating a selectively permeable barrier mediating the nuclear export of key endogenous cargoes such as mRNA, and pre-ribosomal subunits as well as allow for the nuclear import of nuclear proteins and some viral particles. Remarkably, other particles that are not qualified for nucleocytoplasmic transport are repelled from the NPC, unable to translocate. The NPC is made up of over 30 unique proteins, each present in multiples of eight copies. The two primary protein components of the NPC can be simplified as scaffold nucleoporins which form the main structure of the NPC and the phenylalanine-glycine (FG) motif containing nucleoporins (FG-Nups) which anchor to the scaffold and together create the permeability barrier within the pore. Advances in fluorescence microscopy techniques including single-molecule and super-resolution microscopy have made it possible to label and visualize the dynamic components of the NPC as well as track the rapid nucleocytoplasmic transport process of importing and exporting cargoes. The focus of this dissertation will be on live cell fluorescence microscopy application in probing the dynamic components of the NPC as well as tracking the processes of nucleocytoplasmic transport.
Temple University--Theses

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Lolodi, Ogheneochukome. "Kinetic analysis of karyopherin-mediated transport through the nuclear pore complex." 京都大学 (Kyoto University), 2016. http://hdl.handle.net/2433/215696.

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Authors are permitted to post the MBoC PDF of their articles (and/or supplemental material) on their personal websites or in an online institutional repository provided there appears always the proper citation of the manuscript in MBoC and a link to the original publication of the manuscript in MBoC (http://www.molbiolcell.org/site/misc/ifora.xhtml)
Kyoto University (京都大学)
0048
新制・課程博士
博士(生命科学)
甲第19869号
生博第350号
新制||生||46(附属図書館)
32905
京都大学大学院生命科学研究科統合生命科学専攻
(主査)教授河内孝之, 教授藤田尚志, 教授永尾雅哉
学位規則第4条第1項該当

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Bestembayeva, A. "Biophysical properties of the transport barrier in the nuclear pore complex." Thesis, University College London (University of London), 2016. http://discovery.ucl.ac.uk/1474430/.

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The Nuclear Pore Complex (NPC) is a large protein structure found in eukaryotic cells, perforating the nuclear envelope. It mediates bidirectional selective transport between the nucleus and the cytoplasm. The NPC contains a permeability barrier consisting of unstructured nuclear pore proteins. The structure of the permeability barrier is not well defined. As a consequence, various models have been proposed for its structure and functionality. Typically, these models consider the unstructured nuclear pore proteins as weakly or strongly interacting polymers: In the first case nuclear pore proteins protrude from the pore creating an entropic barrier; in the second case they may form a meshwork occupying the central channel, resembling a hydrogel. In this thesis, I measure the nanomechanical properties of this barrier in intact NPCs, and compare them to the properties expected for entropic brushes and gel-like materials. To this end, I carried out nanometre-scale force spectroscopy measurements using Atomic Force Microscopy (AFM). Prior to the measurements the pores were treated with reagents that activated the transport process, thus flushing out the pores to ensure that I was probing the barrier itself instead of cargo stuck in transit. I carried out Laser Scanning Confocal Microscopy experiments to verify this procedure, as well as to measure transport properties of the pores in isolated nuclei. For comparison, I also measure nanomechanical properties of artificial polymer brushes, and set the first steps towards creating protein-coated solid-state nanopores as a reductionist model system for the NPC. My results indicate that the proteins in the NPC form a condensed network, more closely resembling a hydrogel than a brush dominated by entropic interactions.

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Quintana, Star-Lena Jaramillo. "Discrete 3D Model of Molecular Diffusion Through the Nuclear Pore Complex." Master's thesis, Temple University Libraries, 2015. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/343686.

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Mathematics
M.S.
Nuclear pore complexes (NPCs) are passageways that exist within the nuclear envelope (NE) of a eukaryotic cell. Molecular cargo travel through the passageways to either import to the nucleus or export to the cytoplasm of the cell. Efficient export of certain cargo is necessary for maintained health of a cell, and hence, the organism. Traditional methods of observing NPCs lack resolution great enough for scientists to study the many interactions that take place inside of the complex. A discrete 3D model of the molecular diffusion was built to understand how cargo moves through the NPCs and how to improve import and export efficiency of particular molecules. The basis of the model is a Langevin equation that was customized to the environment of the central channel of a NPC. The model incorporated not only the Brownian motion of the molecules, but also the geometry of the channel, the diffusion coefficient for molecules in the fluid of the central channel, and a potential energy (PE) function to describe drifting affects by the dense layers of phenylalanine-glycine (FG) repeats located in the channel and a concentration of transport receptors located on either ends of the NPC. The model simulated the movement of spherical molecules through the NPC and kept track of their location during their transport. The model showed that the cargo’s movement has a distinct dependence on the PE function. The model can be further, and easily, manipulated and used for more comparisons to experimentally determined export efficiency for different cargo.
Temple University--Theses

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Books on the topic "Nuclear pore complex inheritance"

1

Oakford, Lawrence Xavier. The isolation and initial characterization of nuclear envelope "ghosts" and nuclear pore complex morphology from Physarum polycephalum. 1986.

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Book chapters on the topic "Nuclear pore complex inheritance"

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Heese-Peck, Antje, and Natasha V. Raikhel. "The nuclear pore complex." In Protein Trafficking in Plant Cells, 145–62. Dordrecht: Springer Netherlands, 1998. http://dx.doi.org/10.1007/978-94-011-5298-3_8.

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Yu, Jingjie, Joseph Kelich, and Weidong Yang. "Assembly of Nuclear Pore Complex." In Nucleic Acids and Molecular Biology, 1–14. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-77309-4_1.

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Simon, Dan N., and Michael P. Rout. "Cancer and the Nuclear Pore Complex." In Cancer Biology and the Nuclear Envelope, 285–307. New York, NY: Springer New York, 2014. http://dx.doi.org/10.1007/978-1-4899-8032-8_13.

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Fahrenkrog, B., D. Stoffler, and U. Aebi. "Nuclear Pore Complex Architecture and Functional Dynamics." In Nuclear Export of Viral RNAs, 95–117. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/978-3-642-56597-7_5.

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Bodoor, Khaldon, and Brian Burke. "Mitotic Control of Nuclear Pore Complex Assembly." In Nuclear Envelope Dynamics in Embryos and Somatic Cells, 73–86. Boston, MA: Springer US, 2002. http://dx.doi.org/10.1007/978-1-4615-0129-9_6.

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Kahms, Martin, Jana Hüve, and Reiner Peters. "4Pi Microscopy of the Nuclear Pore Complex." In Methods in Molecular Biology, 193–211. New York, NY: Springer New York, 2014. http://dx.doi.org/10.1007/978-1-4939-2080-8_11.

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Boelens, Wilbert C., Catherine Dargemont, and Iain W. Mattaj. "Export of mRNA Through the Nuclear Pore Complex." In Pre-mRNA Processing, 173–86. Berlin, Heidelberg: Springer Berlin Heidelberg, 1995. http://dx.doi.org/10.1007/978-3-662-22325-3_11.

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Milligan, R. A. "A Structural Model for the Nuclear Pore Complex." In Nucleocytoplasmic Transport, 113–22. Berlin, Heidelberg: Springer Berlin Heidelberg, 1986. http://dx.doi.org/10.1007/978-3-642-71565-5_10.

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Akey, Christopher W. "A Modular Model of the Nuclear Pore Complex." In Springer Series in Biophysics, 307–11. Berlin, Heidelberg: Springer Berlin Heidelberg, 1989. http://dx.doi.org/10.1007/978-3-642-73925-5_55.

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Binder, Andreas, and Martin Parniske. "The Nuclear Pore Complex in Symbiosis and Pathogen Defence." In Annual Plant Reviews, 229–54. Oxford, UK: John Wiley & Sons Ltd, 2013. http://dx.doi.org/10.1002/9781118472507.ch8.

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Conference papers on the topic "Nuclear pore complex inheritance"

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Otsuka, Shotaro, Hirohide Takahashi, and Shige Yoshimura. "Single-molecule Structural and Functional Analyses of Nuclear Pore Complex." In 2006 IEEE International Symposium on MicroNanoMechanical and Human Science. IEEE, 2006. http://dx.doi.org/10.1109/mhs.2006.320314.

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Itoh, Goichi, Jinya Nakamura, Koji Kono, Tadashi Watanabe, Hirotada Ohashi, Yu Chen, and Shinya Nagasaki. "Pore-Scale Simulation for Predicting Material Transport Through Porous Media." In 10th International Conference on Nuclear Engineering. ASMEDC, 2002. http://dx.doi.org/10.1115/icone10-22563.

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Microscopic models of real-coded lattice gas automata (RLG) method with a special boundary condition and lattice Boltzmann method (LBM) are developed for simulating three-dimensional fluid dynamics in complex geometry. Those models enable us to simulate pore-scale fluid dynamics that is an essential part for predicting material transport in porous media precisely. For large-scale simulation of porous media with high resolution, the RLG and LBM programs are designed for parallel computation. Simulation results of porous media flow by the LBM with different pressure gradient conditions show quantitative agreements with macroscopic relations of Darcy’s law and Kozeny-Carman equation. As for the efficiency of parallel computing, a standard parallel computation by using MPI (Message Passing Interface) is compared with the hybrid parallel computation of MPI-node parallel technique. The benchmark tests conclude that in case of using large number of computing node, the parallel performance declines due to increase of data communication between nodes and the hybrid parallel computation totally shows better performance in comparison with the standard parallel computation.

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Toumelin, E., C. Torres-Verdin, and S. Chen. "Quantification of Multi-Phase Fluid Saturations in Complex Pore Geometries From Simulations of Nuclear Magnetic Resonance Measurements." In SPE Annual Technical Conference and Exhibition. Society of Petroleum Engineers, 2002. http://dx.doi.org/10.2118/77399-ms.

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Hanzawa, Daiki, Kyosuke Katsumata, and Tomio Okawa. "A Study on High Heat Flux Heat Removal With Boiling Using Porous Microchannel." In 2014 22nd International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/icone22-30104.

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This paper reports the critical heat flux (CHF) enhancement that was observed experimentally when a porous metal was placed in a small flow channel (hereafter, this channel is called a “porous microchannel”). In the porous microchannel, the CHF value increased almost linearly with increased values of the mass flux and the inlet subcooling. In consequence, higher cooling performance was achieved under high mass flux and high inlet subcooling conditions. It was also found that considerable fluctuation of the pressure loss frequently encountered in a small heated channel disappears in the porous microchannel. It was considered that the stabilization of the pressure loss can mainly be attributed to inhibition of the formation of large bubbles. The effects of the material and the pore size of the porous metal were also investigated. Silver and nickel were selected as the porous metal material and the pore size tested was 0.2 and 0.6 mm. In the present experiments, the CHF value was not influenced significantly by the material in spite of the distinct difference of the thermal conductivity between silver and nickel, whilst it was dependent noticeably on the pore size. It was hence suggested that the CHF enhancement observed in this work was mainly caused by the complex thermal-hydraulic field formed in the porous microchannel. Preliminary results of the flow visualization performed to reveal the mechanisms of the CHF enhancement in the porous microchannel was also reported.

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Meekunnasombat, Phongsan, Florian Fichot, and Michel Quintard. "Numerical Simulation of Two-Phase Flow in Severely Damaged Core Geometries." In 14th International Conference on Nuclear Engineering. ASMEDC, 2006. http://dx.doi.org/10.1115/icone14-89300.

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In the event of a severe accident in a nuclear reactor, the oxidation, dissolution and collapse of fuel rods is likely to change dramatically the geometry of the core. A large part of the core would be damaged and would look like porous medium made of randomly distributed pellet fragments, broken claddings and relocated melts. Such a complex medium must be cooled in order to stop the accident progression. IRSN investigates the effectiveness of the water re-flooding mechanism in cooling this medium where complex two-phase flows are likely to exist. A macroscopic model for the prediction of the cooling sequence was developed for the ICARE/CATHARE code (IRSN mechanistic code for severe accidents). It still needs to be improved and assessed. It appears that a better understanding of the flow at the pore scale is necessary. As a result, a direct numerical simulation (DNS) code was developed to investigate the local features of a two-phase flow in complex geometries. In this paper, the Cahn-Hilliard model is used to simulate flows of two immiscible fluids in geometries representing a damaged core. These geometries are synthesized from experimental tomography images (PHEBUS-FP project) in order to study the effects of each degradation feature, such as displacement and fragmentation of the fuel rods and claddings, on the two-phase flow. For example, the presence of fragmented fuel claddings is likely to enhance the trapping of the residual phase (either steam or water) within the medium which leads to less flow fluctuations in the other phase. Such features are clearly shown by DNS calculations. From a series of calculations where the geometry of the porous medium is changed, conclusions are drawn for the impact of rods damage level on the characteristics of two-phase flow in the core.

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Kappes, Ethan, Mateusz Marciniak, Andrew Mills, Robert Muyshondt, Stephen King, Thien D. Nguyen, Yassin A. Hassan, and Victor Ugaz. "Time-Resolved Velocity Measurements in a Matched Refractive Index Facility of Randomly Packed Spheres." In 2018 26th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/icone26-82425.

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Complex geometries and randomly connected void spaces within packed beds have hindered efforts to characterize the underlying transport phenomena occurring within. In this communication, we present our experimental studies on a facility of randomly packed spheres that can be a representative of sections within a reactor core in a nuclear power plant. The results of high-fidelity velocity measurements can be seen using Time-Resolved Particle Image Velocimetry (TR-PIV) at the pore scales and near the wall boundary in the Matched Index of Refraction (MIR) facility. The MIR approach allows for a non-invasive analysis of the flow within packed spheres at the microscopic scales with high temporal and spatial resolution. Flow characteristics obtained from the TR-PIV measurements at various Reynolds numbers are presented. The results include the first- and second-order flow statistics, such as mean velocity, root-mean-square fluctuating velocity and Reynolds stresses. Effects of the wall boundary and Reynolds numbers on flow patterns are currently being investigated. Comparisons of the mean velocities, root-mean-square fluctuating velocities, and Reynolds stress components show the increase of flow mixing and turbulent intensities within the gaps between spheres in the packed bed. Sizes of recirculation regions, however, seem to be independent of the increase of Reynolds numbers.

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Azizoglu, Zulkuf, Artur Posenato Garcia, and Zoya Heidari. "RELIABLE QUANTIFICATION OF PORE GEOMETRY IN CARBONATE ROCKS USING NMR AND ELECTRICAL RESISTIVITY MEASUREMENTS FOR ENHANCED ASSESSMENT OF PERMEABILITY AND CAPILLARY PRESSURE." In 2021 SPWLA 62nd Annual Logging Symposium Online. Society of Petrophysicists and Well Log Analysts, 2021. http://dx.doi.org/10.30632/spwla-2021-0093.

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Reliable and real-time assessment of directional permeability and saturation-dependent capillary pressure are utterly important because they significantly affect the exploitation strategies. Conventional well-log-based methods (e.g., NMR-based, saturation-height analysis, resistivity-based, correlation-based) are either highly dependent on calibration efforts or rely on model parameters which are difficult to obtain in real-time and make them dependent on core measurements. Moreover, most conventional methods for assessment of directional permeability and saturation-dependent capillary pressure fail in the presence of multi-modal pore-size distribution. Recent publications suggested that integration of transverse Nuclear Magnetic Resonance (T2 NMR) and resistivity measurements enables assessment of pore-throat-size distribution as well as permeability and capillary pressure. However, the reliability of these methods is questionable in rocks with complex/multi-modal pore geometry. The objectives of this paper include (a) reliably estimating a variable constriction factor (a geometric parameter which relates the pore- and throat-size) in rocks with complex pore geometry to accurately quantify pore geometry, which is the main contribution of this work, (b) developing a new rock physics workflow for integrating NMR and electrical conductivity for assessment of permeability and capillary pressure that takes into account a variable constriction factor, and (c) verifying the reliability of the introduced workflow using core scale measurements. The proposed workflow starts with calculating pore-body-size distribution from NMR T2 distribution. Then, we combine electrical resistivity and pore-size distribution to estimate the distribution of constriction factor in the pore structure. Next, we determine pore- throat-size distribution using the estimated variable constriction factor. We then introduce a new permeability model which takes variable constriction factor into account. The inputs to the permeability model include throat-size distribution, tortuosity, and porosity. Finally, we calculate saturation-dependent capillary pressure using the estimated throat-size distribution. We successfully verified the reliability of the introduced workflow in the core-scale domain in carbonate rock samples with complex pore structure. The permeability estimates obtained by the new workflow yielded less than 7% average relative error when compared against core measurements. We also observed a good agreement between the throat-size distribution and capillary pressure estimated from the new workflow and the ones acquired from MICP (mercury injection capillary pressure) measurements. Results also confirmed that integration of a variable constriction factor improves directional permeability estimates compared to cases where an effective constriction factor was used to quantify pore-throat size distribution in rocks with multi-modal pore-size distribution.

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Hursan, Gabor, Wei Shao, Ron Balliet, and Yasir Farooq. "Eliminating Diffusion Effects from NMR Logging Data for Enhanced Carbonate Pore Typing." In SPE Annual Technical Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/206233-ms.

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Abstract Transverse relaxation (T2) times measured by multi-frequency, multi-gradient nuclear magnetic resonance (NMR) logging tools are affected by diffusion-induced enhanced relaxation which reduces the sensitivity to pore size in slow-relaxing formations such as macroporous carbonates and complicates the integration with zero-gradient core NMR data. We propose a solution for eliminating the diffusion-related uncertainties using intrinsic T2 distributions, obtained by a new inversion-forward modeling-inversion (IFMI) method, for carbonate pore typing applications. The NMR logs presented in this paper are based on data measured at five frequencies where the static magnetic field gradient varies from 26 to 55 G/cm. The high-quality echo signals are processed using a three-step IFMI differential signal analysis approach which nullifies diffusion effects due to the tool gradient and the potentially present internal gradient caused by paramagnetic minerals in the formation. The resulting diffusion-free intrinsic T2 distribution accentuates fine pore size variations and allows better discernment of micro-, meso-, and macropore systems of complex carbonate reservoirs. Multi-frequency NMR data, acquired in multiple wells, were processed and analyzed in several ways. First, apparent T2 distributions were obtained separately for individual frequencies. Discrepancies between the results of different frequencies clearly indicated that in macro- and mesoporous carbonates the diffusion effect is significant even with TE=0.3ms. This leads a peak broadening observed in the apparent T2 spectrum from conventional NMR processing, where echo trains from different frequencies are averaged in time-domain prior to the inversion. With the IFMI processing, individual-frequency echo trains are first pre-processed using a 2D NMR inversion whose results are used to forward model a diffusion-free echo train without prior assumptions on reservoir fluid diffusivity D. A second inversion, applied on the diffusion-free echo train, yields the intrinsic T2 distribution. The intrinsic T2 distribution has a noticeably higher spectral resolution in carbonate formations where diffusion effect is significant. The intrinsic T2 logs are expected to be more consistent with other gradient-free NMR measurements such as core NMR or LWD NMR data sets.

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Eyvazzadeh, Ramsin, Abdullatif Al-Omair, Majed Kanfar, and Achong Christon. "Low Resistivity Pay Carbonates: A Practical Approach to Quantify Water Saturation Using a Modified Archie's Model." In SPE Annual Technical Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/206096-ms.

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Abstract A detailed description of a modified Archie's equation is proposed to accurately quantify water saturation within low resistivity/low contrast pay carbonates. The majority of previous work on low resistivity/low contrast reservoirs focused on clastics, namely, thin beds and/or clay effects on resistivity measurements. Recent publications have highlighted a "non-Archie" behavior in carbonates with complex pore structures. Several theoretical models were introduced, but new practical applications were not derived to solve this issue. Built upon previous theoretical research in a holistic approach, new models and workflows have been developed. Specifically, utilizing a combination of machine learning algorithms, nuclear magnetic resonance (NMR), core and geological data, field specific calibrated equations to compute water saturation (Sw) in complex carbonate formations are presented. Essentially, these new models partition the porosity into pore spaces and calculate their relative contribution to water saturation in each pore space. These calibrated equations robustly produce results that have proven invaluable in pay identification, well placement, and have greatly enhanced the ability to manage these types of reservoirs. This paper initially explains the theory behind the development of the analysis illustrating workflows and validation techniques used to qualify this methodology. A key benefit performing this research is the utilization of machine-learning algorithms to predict NMR derived values in wells that do not have NMR data. Several examples explore where results of this analysis are compared to dynamic testing, formation testing and laboratory measured samples to validate and demonstrate the utility of this new analysis.

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Zhao, Zuo AN, Yue Wang, Qiang Lai, Kai Xuan Li, Xian Ran Zhao, Jin Long Wu, Hai Peng Zhao, and Dai Guo Yu. "Fluid Identification Derived from Non-Electric Measurements and Reservoir Characterization of Tight Carbonate in Sichuan Basin, China." In SPE Annual Technical Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/205926-ms.

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Abstract Natural gas production in the Sichuan Basin reached 30 billion m3 in 2020, but the gap between this and the production goal of 50 billion m3 in 2025 requires further exploration. The complex mineralogy and low porosity in tight carbonate reservoirs lower the accuracy of formation water saturation calculation from Archie's equation, which brings uncertainties to the reservoir characterization. It is, therefore, necessary to incorporate other methods as supplements to methods based on resistivities. This paper outlines a method that incorporates wireline induced gamma spectroscopy, nuclear magnetic resonance (NMR), array dielectric, and borehole images. Spectroscopy is not only utilized to estimate the mineralogy of the reservoir, but it also provides non-electric measurements, such as chlorine concentration and thermal neutron capture cross-section (sigma). The amount of chlorine in the formation is proportional to the water volume in the reservoir, thus formation water saturation. Sigma is also an indicator of the formation water saturation. It enables formation water saturation calculation without resistivities. Case studies are presented from carbonate reservoirs in the Sichuan Basin, China. A robust and comprehensive petrophysical description of mineralogy, porosity, pore geometry, free fluid volume, rock type, and formation water saturation is presented. Calculation of formation water saturation from chlorine and sigma proves to be successful in both water-based mud and oil-based mud environments. The depth of investigation (DOI) of chlorine from spectroscopy is about 8 to 10 in. for 90% of the signal. The various DOI of different measurements must be considered when performing the fluid identification. Bound fluid saturation could reach more than 50% in tight carbonate reservoirs. Formation water saturation is not the only factor that determines the fluid type. Free fluid saturation from NMR must be incorporated. Finally, a robust methodology integrating formation water saturation derived from dielectric and spectroscopy, and free fluid saturation derived from NMR shows great advantage in fluid identification in tight carbonate reservoirs. This paper discusses a novel combination of wireline logging tools for the fluid identification of tight carbonate reservoir in Sichuan Basin. It lowers the uncertainty in the estimation of formation water saturation when application of resistivities is limited in oil-based mud environments. The gas zones identified by the new method have promising gas productions. The workflow can also be applied to other tight carbonate plays in China.

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