Prediction of Archie’s cementation factor from porosity and permeability through specific surface

Geophysics ◽  
2008 ◽  
Vol 73 (2) ◽  
pp. E81-E87 ◽  
Author(s):  
Casper Olsen ◽  
Thanong Hongdul ◽  
Ida Lykke Fabricius

Based on Archie’s cementation factor as measured on North Sea chalk and on published data, we explore how the cementation factor depends on other physical properties of the chalk. A relationship between cementation factor and specific surface with respect to bulk volume is obtained for chalk. This leads to how Archie’s cementation factor may be predicted from porosity and permeability for chalk as well as for sandstone. A common relationship between cementation factor and specific surface with respect to bulk volume calculated from porosity and permeability is obtained. As an alternative, the [Formula: see text]-factor in Archie’s equation is related to specific surface with respect to bulk volume, but the relationship is less clear than the simple relationship between cementation factor and specific surface.

2004 ◽  
Vol 82 (3) ◽  
pp. 516-524 ◽  
Author(s):  
Fritz Trillmich ◽  
Cornelia Kraus ◽  
Joachim Künkele ◽  
Matthias Asher ◽  
Mario Clara ◽  
...  

Two little-known species of guinea-pig from the genera Cavia and Galea (Cavia magna Ximénez, 1980 and Galea sp. nov.) have recently been studied in more detail with respect to their behavior, social structure, and mating system. To determine the specific distinctness of these little-known species from Cavia aperea Erxleben, 1777 and Galea musteloides Meyen, 1832, crossbreeding between species was tried and it demonstrated that the two Cavia species will rarely cross in captivity to produce hybrids of much reduced fertility, whereas the Galea species could not be crossed. To analyze the phylogenetic position of C. magna and Galea sp. nov., we present an analysis based on major parts of the 12S (778 base pair) and 16S genes of mitochondrial RNA (1435 base pair) in conjunction with corresponding data on all other genera of the Caviinae. We also determined the relationship between C. magna and the sympatric wild guinea-pig (C. aperea) and its domestic form (Cavia aperea f. porcellus (Linnaeus, 1758)). Phylogenetic and distance analysis of all genera of cavies (Cavia (two species), Galea (two species), Kerodon, Microcavia) showed the close relationship of C. magna with C. aperea and the latter's particularly low genetic distance to C. aperea f. porcellus. Galea sp. nov. differed markedly from G. musteloides. Of the three genera, Galea appears most distinct. The genus Kerodon clustered with the genus Hydrochaeris, supporting the previous conclusion by Rowe and Honeycutt (2002. Mol. Biol. Evol. 19: 263–277) regarding the placement of the genus Hydrochaeris within the Caviidae. Recently published data on the social systems of the above-mentioned cavy species, however, show their great inter- and intra-specific social flexibility and contradict the interpretation of the same authors about a simple relationship between phylogeny and social systems in the Caviidae.


1998 ◽  
Vol 1 (03) ◽  
pp. 245-251 ◽  
Author(s):  
Jeanette Mortensen ◽  
Finn Engstrom ◽  
Ida Lind

Summary The origin of the difference in the relationship between permeability and porosity for Danian and Maastrichtian chalk from the Gorm field offshore Denmark has been investigated. The investigation was based on 300 sets of core data (He-expansion porosity and air permeability) from Well Gorm N-22X. On 24 of the core plugs, the specific surface was determined by BET and, on 14 of these samples, image analysis was made. The data were rationalized by the use of the Kozeny equation and it was found that each geologic unit had a characteristic relationship among porosity, permeability, and specific surface. Furthermore, it was found that the nature of porosity (intrafossil, intergranular, etc.) had no significant influence on the air permeability, so that the permeability of the chalk can be calculated from total porosity and specific surface. Kozeny's empirical constant, c, was determined analytically from a simple porosity model and Poiseuille's law. Introduction Experience has illustrated that to a first approximation, porosity and the logarithm of permeability are well correlated in the North Sea chalk. However, different stratigraphical units have distinctly different porosity-permeability relations. For a given porosity, the permeability of chalk of Maastrichtian age is, e.g., on average, larger than the permeability of chalk of Danian age. The cause for the differences in porosity-permeability relationships between the chalk units is not well documented in literature, but the size of pores and particles, and the surface characteristics of the particles are likely controlling factors. This study was undertaken to obtain a simple model for the relationship among porosity, permeability, and specific surface for reservoir chalk irrespective of stratigraphic unit, and to evaluate the usefulness of image-analysis data relative to laboratory data. To meet this purpose, we have studied core data from a chalk field (the Gorm field) applying the Kozeny equation.


2012 ◽  
Vol 616-618 ◽  
pp. 228-233
Author(s):  
Zhong Chun Sun ◽  
Zhong Hong Chen ◽  
Yu Hua Kong ◽  
Wen Liu ◽  
Men Yun Yang

The physical properties of reservoirs determine the ability on accumulating hydrocarbon. As one of the unconventional hydrocarbon reservoirs, the volcanics own the different characteristics from the clastic rocks on physical properties. The study on the relationship between physical and electrical properties of deep volcanic reservoirs was conducted, using the Luxi area of Junggar basin as an example. By our study, some conclusions have been made: The heterogeneity of physical properties is strong in volcanic rocks whose porosity and permeability vary in different lithology and lithofacies; different rocks in a same well have various values of porosity and permeability, and a certain type of volcanic rock has different values of porosity and permeability in diverse wells. According to measured data, the value of porosity an permeability in erupting and effusive facies area are high, while in volcanic channel and extrusive facies as well as volcanic sedimentation facies are low. Unlike the clastic rocks, in volcanic rocks there is little relationship between porosity and permeability and all of them do not have close relationship to the buried depth. Different electrical responses have different relationship with the porosity of one certain lithology, while one certain electrical property has different responses for the porosities of different lithologies; comparatively speaking, the porosities of tuffites, breccia correlate intensively with GR, SP and AC, so these electrical parameters can be utilized to predict the physical properties. This study illustrated that the relativities between porosity and GR, AC, and SP are Por=-0.6189×GR+52.691 (R2=0.9311), Por =-0.3771×AC + 34.5 (R2=0.8876) and Por = 2.1458×SP + 79.404 (R2=0.8236).


2020 ◽  
Vol 498 (4) ◽  
pp. 4936-4942
Author(s):  
Fereshteh Rajabi ◽  
Mohammed A Chamma ◽  
Christopher M Wyenberg ◽  
Abhilash Mathews ◽  
Martin Houde

ABSTRACT We consider a simple dynamical and relativistic model to explain the spectro-temporal structure often displayed by repeating fast radio bursts (FRBs). We show how this model can account for the downward frequency drift in a sequence of sub-bursts of increasing arrival time (the ‘sad trombone’ effect) and their tendency for exhibiting a reduced pulse width with increasing frequency of observation. Most importantly, this model also predicts a systematic inverse relationship between the (steeper) slope of the frequency drift observed within a single sub-burst and its temporal duration. Using already published data for FRB 121102, we find and verify the relationship predicted by this model. We therefore argue that the overall behaviour observed for this object as a function of frequency is consistent with an underlying narrow-band emission process, where the wide-band nature of the measured FRB spectrum is due to relativistic motions. Although this scenario and the simple dynamics we consider could be applied to other theories, they are well suited for a model based upon Dicke’s superradiance as the physical process responsible for FRB radiation in this and similar sources.


2021 ◽  
pp. jgs2021-071
Author(s):  
Roger Burgess ◽  
David Jolley ◽  
Adrian Hartley

The Triassic sediments of the Central North Sea (CNS) are considered to have been deposited in a continental environment under a semi-arid climate. The Skagerrak Formation in particular, comprises an alternation of sandstone and mudstone members, the development of which is considered to be climatically driven. However, conflicting models exist as to how climate influences member deposition. Here we analyse the climatic signal using a multivariate statistical approach in which de-trended correspondence analysis (DCA) is applied to palynological observations to quantify environmental reconstruction. Using DCA it has been possible to define paleoecological groups and construct a relative hydrological state trend showing hydrological conditions within the centre of the CNS basin during the Triassic. The resultant trends reveal that the relationship between hydrological conditions in the basin and the development of individual sandstones and mudstone members is perhaps not a simple as indicated by existing models. In particular our data suggest that whilst influenced by broader climate trends, in the basin centre, there is no simple relationship between climate change and sandstone/mudstone development. The data also indicates that the Julius and Jonathan mudstone members were deposited under differing hydrological conditions. The DCA trends shown here also suggest that the Carnian Pluvial Episode (CPE) documented from the South Permian Basin and Tethys is not expressed in the CNS.


2011 ◽  
Vol 65 (12) ◽  
pp. 1293-1297
Author(s):  
Keiko Hashiguchi ◽  
Takehiro Yoshimatsu ◽  
Masanori Kawashima

The Condor ◽  
2007 ◽  
Vol 109 (2) ◽  
pp. 441-446 ◽  
Author(s):  
Niall H.K. Burton

Abstract The relationship between nest entrance orientation and latitude among ground-nesting passerines was reviewed using published information. Data were collated for seven North American and European species. Pooling within-species comparisons, there was a clear trend from a preference for north-facing nests at lower latitudes to eastward- or southward-facing nests farther north. Orientations differed significantly in eight of 12 cases for which statistical comparison was possible, means differing in the expected direction in six of these cases. These results highlight how the influence of solar radiation on nest microclimate typically delineates preferred nest orientation in these species, i.e., at lower latitudes, the need for shade results in a preference for northward orientations; at mid latitudes, eastward orientations predominate, reflecting a probable balance between the benefits of warmth in the early morning and shade in the afternoon; while at high latitudes, nests may be oriented southward to gain warmth throughout the day.


2021 ◽  
Vol 114 (1) ◽  
Author(s):  
Alba Zappone ◽  
Eduard Kissling

AbstractThe Swiss Atlas of Physical Properties of Rocks (SAPHYR) project aims at centralize, uniform, and digitize dispersed and often hardly accessible laboratory data on physical properties of rocks from Switzerland and surrounding regions. The goal of SAPHYR is to make the quality-controlled and homogenized data digitally accessible to an open public, including industrial, engineering, land and resource planning companies as well as governmental and academic institutions, or simply common people interested in rock physics. The physical properties, derived from pre-existing literature or newly measured, are density, porosity and permeability as well as seismic, magnetic, thermal and electrical properties. The data were collected on samples either from outcrops or from tunnels and boreholes. At present, data from literature have been collected extensively for density, porosity, seismic and thermal properties. In the past years, effort has been placed especially on collecting samples and measuring the physical properties of rock types that were poorly documented in literature. A workflow for quality control on reliability and completeness of the data was established. We made the attempt to quantify the variability and the uncertainty of the data. The database has been recently transferred to the Federal Office of Topography swisstopo with the aim to develop the necessary tools to query the database and open it to the public. Laboratory measurements are continuously collected, therefore the database is ongoing and in continuous development. The spatial distribution of the physical properties can be visualized as maps using simple GIS tools. Here the distribution of bulk density and velocity at room conditions are presented as examples of data representation; the methodology to produce these maps is described in detail. Moreover we also present an exemplification of the use of specific datasets, for which pressure and temperatures derivatives are available, to develop crustal models.


2012 ◽  
Vol 501 ◽  
pp. 442-447
Author(s):  
Ping Fu ◽  
Feng Bao Bai ◽  
Chuan Sheng Wang ◽  
Shan Hu Li

In this paper adopting the orthogonal method, self-developed compound formulation had tested, and the relationship between the physical properties of vulcanized rubber and rectangular synchronous rotor mixer parameters had researched. The results showed that when the fill factor was 0.6, the rotor speed was 70r/min, cooling water temperature was 45 °C, pressure on the top bolt was 0.8Mpa, the physical properties of the vulcanized rubber was best.


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