Modeling Sand Occurrence in Petroleum Production

2019 ◽  
Vol 142 (4) ◽  
Author(s):  
Kingsley E. Abhulimen

Abstract This paper presents an advanced model to predict sand occurrence and accurately estimate volumetric sand produced in petroleum production. The sand factors Ks(t), derived from the linear time combination of likelihood of occurrence λm(t) of KRS and KFS, were used to determine sand occurrence and estimate its volumetric production around well bore systems. Therefore, the measured laboratory and field log core data of elastic properties were simulated for the mechanical and hydrodynamic decementation at unobserved multiple field locations of equiprobable realizations. The critical limits for mechanical rock failure and hydrodynamic sand production were defined at sand factors equal to 1 in absolute terms. The sand model results show two distinct gradient points observed for laboratory plots of sand elastic properties: core displacement length defined as the loading point of mechanical rock failure and the flooding point for hydrodynamic fluidized incipient sand production. However, plots of elastic properties with the core length for field case show significant deviations with multiple loading rock failure and flooding sand production points most likely caused by the complex nature of rock matrix heterogeneity for the fields studied.

1964 ◽  
Vol 37 (5) ◽  
pp. 1365-1390 ◽  
Author(s):  
Samuel K. Clark

Abstract The increased use of cord- and filament-reinforced materials in structural applications during the last few years has resulted in a greater interest in their elastic properties. In part the reason for this may be found by considering the basic nature of redundant structures, in which the loads carried by individual cords are determined to some extent by the elastic characteristics of the entire system. In such situations, a knowledge of elastic characteristics becomes important to structural design practice. As a second reason for increased attention to the elastic properties of such materials, one might cite the body of work which is now developing in the general area of filamentary reinforcement of materials. A knowledge of elastic characteristics is important in obtaining optimum reinforcement properties, and such studies inevitably lead to a clearer understanding of the internal stress-states of all reinforced materials. One result of all this activity is that much of the work done in the areas of fiberglass and whisker reinforcement increases the general understanding, in a broad way, of the action of cord-reinforced rubber since in many respects the problems are similar, although major differences do exist in the structure of the reinforcement itself. The elastic properties of cord-rubber materials are understood today much better than they were even ten or fifteen years ago. A great deal of this development has paralleled, and is well represented by, internal stress analysis techniques developed for what is perhaps the primary utilization of cord-reinforced rubber, namely, the pneumatic tire. In the case of the pneumatic tire, these stress analysis techniques have essentially followed three distinct phases. In the first, the anisotropic nature of such materials was completely ignored and loads and stresses were determined on the basis of assuming the materials to be isotropic or unreinforced. In the case of shell structures, this is the equivalent of calculating the statically determinate membrane stresses. In some cases such information was valuable and in a few instances it comprised a major portion of the effects being studied so that some reliance could be placed on such an analysis. However, in general, due to the complex nature of such reinforced materials, little faith can be given to analyses based on isotropic conditions.


In a previous communication* an account was given of a preliminary exploration, chiefly by X-ray methods, of the problem of the molecular structure of animal hairs. The present paper is a natural continuation of the record, in which earlier tentative suggestions are either confirmed or rejected, and an attempt is made to lay bare the general structural principles underlying the properties of the protein, keratin . It will be unnecessary here to outline once more the historical development of the subject; we shall proceed at once to the main point of this introductory section, which is to give what appears to be the solution of the problem before setting out in detail the experimental facts and arguments leading up to it. Such a procedure is advisable because of the complex nature of the properties under discussion ; such a long series of experiments have been involved in their elucidation, that without some sort of preliminary statement of the chief conclusions, the issue is apt to grow confused.


Author(s):  
Amy M. McGough ◽  
Robert Josephs

The remarkable deformability of the erythrocyte derives in large part from the elastic properties of spectrin, the major component of the membrane skeleton. It is generally accepted that spectrin's elasticity arises from marked conformational changes which include variations in its overall length (1). In this work the structure of spectrin in partially expanded membrane skeletons was studied by electron microscopy to determine the molecular basis for spectrin's elastic properties. Spectrin molecules were analysed with respect to three features: length, conformation, and quaternary structure. The results of these studies lead to a model of how spectrin mediates the elastic deformation of the erythrocyte.Membrane skeletons were isolated from erythrocyte membrane ghosts, negatively stained, and examined by transmission electron microscopy (2). Particle lengths and end-to-end distances were measured from enlarged prints using the computer program MACMEASURE. Spectrin conformation (straightness) was assessed by calculating the particles’ correlation length by iterative approximation (3). Digitised spectrin images were correlation averaged or Fourier filtered to improve their signal-to-noise ratios. Three-dimensional reconstructions were performed using a suite of programs which were based on the filtered back-projection algorithm and executed on a cluster of Microvax 3200 workstations (4).


Author(s):  
M.B. Braunfeld ◽  
M. Moritz ◽  
B.M. Alberts ◽  
J.W. Sedat ◽  
D.A. Agard

In animal cells, the centrosome functions as the primary microtubule organizing center (MTOC). As such the centrosome plays a vital role in determining a cell's shape, migration, and perhaps most importantly, its division. Despite the obvious importance of this organelle little is known about centrosomal regulation, duplication, or how it nucleates microtubules. Furthermore, no high resolution model for centrosomal structure exists.We have used automated electron tomography, and reconstruction techniques in an attempt to better understand the complex nature of the centrosome. Additionally we hope to identify nucleation sites for microtubule growth.Centrosomes were isolated from early Drosophila embryos. Briefly, after large organelles and debris from homogenized embryos were pelleted, the resulting supernatant was separated on a sucrose velocity gradient. Fractions were collected and assayed for centrosome-mediated microtubule -nucleating activity by incubating with fluorescently-labeled tubulin subunits. The resulting microtubule asters were then spun onto coverslips and viewed by fluorescence microscopy.


Author(s):  
A.R. Thölén

Thin electron microscope specimens often contain irregular bend contours (Figs. 1-3). Very regular bend patterns have, however, been observed around holes in some ion-milled specimens. The purpose of this investigation is twofold. Firstly, to find the geometry of bent specimens and the elastic properties of extremely thin foils and secondly, to obtain more information about the background to the observed regular patterns.The specimen surface is described by z = f(x,y,p), where p is a parameter, eg. the radius of curvature of a sphere. The beam is entering along the z—direction, which coincides with the foil normal, FN, of the undisturbed crystal surface (z = 0). We have here used FN = [001]. Furthermore some low indexed reflections are chosen around the pole FN and in our fcc crystal the following g-vectors are selected:


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