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The authors presented an article last year on colloidal properties of claysuspensions in which they attempted to sustain the position that the behaviorof clay suspensions is due primarily to the mechanical interference of theplaty particles, the nature and extent of the interference being profoundlyinfluenced by the character of the surfaces of the particles, which in turn isdetermined primarily by the nature and amount of adsorbed foreign materialsheld on the surface of the particles by forces which are predominantly chemicalin type. The following discussion is a continuation of that article to extendthese same interpretative points of view to the behavior of clay gels. Insightinto the mechanism of gelation is certainly of outstanding importance in thehandling of drilling muds. In the former article it was suggested that the thin, flat plates thatconstitute the ultimate clay particles may build up aggregates by theoverlapping of the ultimate plates face to face much longer and perhaps alsomuch wider than the ultimate plates themselves, but not appreciably thicker.Exhaustive microscopic examinations of characteristic clays show no tendencyfor the larger particles, clearly visible under the microscope, to orientthemselves in this way. It is true that the gelation of the clays is dueprimarily to the smallest particles, unresolvable other than by theultramicroscope, so that the possibility of the development by them of anoverlapping structure is not excluded. Furthermore, as one approaches the limitof resolving power of the microscope, the difficulty of observing accuratelythe shapes and relative positions of particles increases excessively. However, in the absence of any observable tendency toward overlapping orientation of thelarge, visible particles, one hesitates to ascribe such a tendency to thesmaller particles beyond the range of visibility. Should it develop that onemust exclude the assumption of overlapping orientation, the explanationsoffered in the previous article are changed in only one respect; namely, onewould now have to assume that the ultimate particles themselves have length, and probably also width, very large in comparison with their thickness.
CaO/Na.O corrected for CO -. Moisture and CO. were determined together at 18.8 per cent. However, they always contain water of chemical constitution, as shown by Table 1. Manuscript received at the office of the Institute Oct. 13, 1934. There is little doubt that plastic, claylike properties are not developed until the particle size is below about 0.01 mm. Clays also contain appreciable percentages of particles larger than 0.01 mm., usually considered as impurities, silt, sand, etc. Because of their size, below the resolving power of the microscope, the shape of the particles is difficult to determine. Several observers have reported the presence of flat, platelike crystals in clay when examined microscopically. Whether this is true of all clays is not known, but facts point to the conclusion that even the small particles may be platelike.
With the new insight into the mechanism of movement of oil and gas through the formations in which they occur, achieved by the production engineer, it is clear that the latter will need to utilize in the solution of his own problems much of the information outlined above. It is the purpose of this paper to outline the portions of that information that seem most certain to prove of importance in production work. While it is true that petroleum always consists of highly complex mixtures of hydrocarbons, none the less understanding of the behavior of the mixture must be based upon a knowledge of the properties of the pure components. However, in view of the tremendous number of hydrocarbons existing in petroleum, the determination and formulation of the properties of all of them would seem a discouraging task. The difficulty of the situation is increased by the undoubted facts that the overwhelming majority of chemical individuals in petroleum have never been isolated as pure compounds, none of their physical properties have been determined and even their chemical constitution is unknown. The situation would be hopeless were it not for the fact that certain extraordinary correlations of important properties of various hydrocarbons have been discovered which make it possible to predict those properties for a given chemical individual on the basis of a very limited characterization of it. Thus one can predict the vapor-pressure curve of an unknown hydrocarbon over a considerable range from the knowledge of a - Professor of Chemical Engineering, Massachusetts Institute of Technology. Indeed, it is not impossible that a knowledge of three characteristics of an unknown hydrocarbon, properly chosen, may turn out to be sufficient to determine all its more important physical properties. Clearly, therefore, one must start with a knowledge of the properties of individual hydrocarbons, interpreted and generalized in the light of these correlations. It must be emphasized that these correlations are not absolute.
- North America > United States > Massachusetts (0.34)
- North America > United States > Oklahoma (0.28)
- North America > United States > Texas (0.28)
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- Energy > Oil & Gas > Downstream (1.00)