Viscosity Characteristics of Clays in Connection with Drilling Muds

Abstract

FOR the past few years a great amount of work has been done on the viscosity characteristics and gelation of clay suspensions, much of which has been reported in papers published by the Institute.7,12, 18,19,24 Important reviews have been made elsewhere by Evans and Reid,l° Marshall 20 and Clews, Macey and Rigby, 8 the last two on the general properties of clay. It is unnecessary, therefore, to recapitulate past work beyond recalling that three explanations for the high viscosity and gelation of clay suspensions have been put forward. For lack of more exact nomenclature, these may be called the water hull,l6 mechanical interference 19 and attraction-repulsion 13 theories. The first pictures the clay particles as surrounded by relatively rigid water envelopes, which increase effective volume i the second emphasizes the mechanical interference of platy particles or their agglomerates i while in the third the particles are assumed to be held relatively rigidly at a distance from each other determined by the balance between the attractive (van der Waal's) forces and the electrical repulsions of the charges. 13, 14 This article presents fresh data on clay suspensions, particularly on the influence of previous flow history of the suspensions, specific contra-ions, temperature, solvation and particle size, in an attempt to contribute to the solution of the problem. EXPERIMENTAL PROCEDUREPreparation of Samples.-Suspensions of the raw clays were prepared by adding the clay to water with vigorous stirring and allowing the mixture to stand for several hours. In bentonite suspensions, the sand that settled was removed. Many of the suspensions were put through a homogenizer for deflocculation before use. The suspensions containing alcohol and pyridine were prepared by gradually adding a known quantity of the C.P. reagent to the clay, shaking after each addition. They were then allowed to stand for two days before measurements were taken. All concentrations are expressed on a weight per cent basis.

Viscosimetric Constants of Suspensions of Clay-Polymer Complexes

“…His work in large part stimulated these studies; so, too, did the work of Granquist (1959). The many earlier studies of the rheology of drilling muds were concerned chiefly with yield points and thixotropy rather than with aggregate morphology of clay--organic complexes (Broughton and Hand, 1938;Norton, Johnson and Lawrence, 1944;Langston and Pask, 1958 ;Schulz, 1957). The well known, critical work of ScottBlair (Scott-Blair and Crowther, 1929;Scott-Blair, 1930) with soft clays was similarly directed.…”