摘要:

The rheological properties were studied for suspensions of two titanium dioxide (Anatase) powders with different particle sizes dispersed in water by adding sodium pyrophosphate as the dispersing agent. Using a capillary viscometer, flow measurements were made under conditions of varying amounts of dispersing agent as well as shear histories of suspensions. The sedimentation behavior and zeta‐potential were also measured as a means of studying the stability of the suspensions against flocculation. The onset of dilatancy was observed at higher shear rates and the extent of dilatancy decreased with an increase in a dispersion stability varied by the amount of dispersing agent as well as in a degree of dispersion varied by the shear history. The suspension with large particles showed dilatant behavior similar to that of the stable suspensions. Relationships between the rheological properties and the stability of suspensions against flocculation were discussed on the basis of the theory of the stability of lyophobic colloids.

ISSN:0148-6055    

DOI:10.1122/1.549521

出版商:The Society of Rheology    

年代:1979

数据来源: AIP

摘要:

The flow of a creeping polar fluid within a circular cylinder generated by (a) fluid entering and leaving through slots in the cylinder wall, and (b) the rotation of part of the wall are analyzed. In both cases exact solutions are obtained, streamlines are sketched for special cases, and the deviation from a Newtonian fluid is observed. The dependence of polar fluids on two dimensionless parameters, the coupling number and the length ratio, is discussed.

ISSN:0148-6055    

DOI:10.1122/1.549515

出版商:The Society of Rheology    

年代:1979

数据来源: AIP

摘要:

A modified form of the BKZ elastic fluid is presented. The specific form chosen is used to describe the normal stress and shear stress responses of PMMA in two‐step torsion strain histories. Our results show that the modified form of the BKZ theory does not account for mechanical aging effects in PMMA. However, the response of mechanically conditioned PMMA to the strain histories tested is described by the modified theory. An interesting result is that the normal stress response to a two‐step strain history in which the second step strain is half the first step is predicted to be independent of the duration of the first step and identical to the response to a single‐step history at the strain level of the second step. This response is observed experimentally.

ISSN:0148-6055    

DOI:10.1122/1.549522

出版商:The Society of Rheology    

年代:1979

数据来源: AIP

摘要:

The two major difficulties in producing petroleum from subsurface formations by fluid injection are poor displacement efficiency and poor sweep efficiency. Engineering and chemical means are being investigated to improve the performance of these recovery controlling processes. The need for improving the recovery of petroleum from known oilfields becomes obvious when it is realized that on the average only about one‐third of the oil originally in place at the time of discovery is ever produced. This fact coupled with the fact that our nation uses about 18 million barrels of petroleum per day while producing less than half this amount emphasizes the need for this improvement. Interfacially active compounds suitable for oilfield application now are available for use. Similarly, polymers of various kinds also are available in quantities sufficient for use in petroleum recovery. The utilization of these kinds of materials will be discussed together with the desired effects and limitation of their use for oil recovery purposes. The chemical and physical principles of the newest enhanced oil recovery processes that are currently under development by the Government and the petroleum industry will be discussed.

ISSN:0148-6055    

DOI:10.1122/1.549523

出版商:The Society of Rheology    

年代:1979

数据来源: AIP

摘要:

Experiments conducted recently in both laboratory cores as well as in some oil fields suggested that the poor efficiency of oil recovery might be due to emulsion stability problems in the low tension surfactant or micellar processes. Thus, an important opportunity for improving surfactant/polymer or caustic system performance for enhanced oil recovery lies in learning to what extent the coalescence phenomena and hence stability of emulsions flowing through the porous media affect oil recovery processes. Earlier studies had concluded that low interfacial tensions and therefore a high capillary number must be achieved to obtain displacement of all residual oil in surfactant/polymer flooding processes. Largely ignored has been the role played by the coalescence of oil ganglia and hence emulsion stability. It has been shown recently in our laboratory and at other institutions that low interfacial tension promoted considerable emulsification and that emulsion formation and coalescence can significantly affect the results of laboratory oil‐recovery tests. Rapid coalescence could be correlated with low interfacial viscosity but not with low interfacial tension for the systems studied. This paper attempts to present an assessment of the factors that influence the coalescence‐rupture processes, which in turn may affect oil bank formation and emulsion stability in surfactant/polymer and caustic systems. The scope of this paper is intentionally limited to a preliminary discussion of coalescence and its correlation with interfacial properties and displacement processes. Further investigation is needed to clarify and establish conclusively the role of coalescence phenomena and emulsion stability in the basic mechanisms of oil recovery processes involving the use of chemicals.

ISSN:0148-6055    

DOI:10.1122/1.549524

出版商:The Society of Rheology    

年代:1979

数据来源: AIP

摘要:

Enhanced oil recovery processes require mobility control for proper displacement of oil and water from porous media. In some processes, concentrated or dilute surfactant systems can be used to recover oil following waterflood operations. These surfactant systems are, in turn, displaced by dilute aqueous polymer solutions. To minimize “fingering” of one chemical system into another, the mobility of the displacing fluid must be no greater than the mobility of the fluid being displaced. Therefore, rheological properties of materials used for enhanced oil recovery are important. Potentially useful surfactant formulations consist of water, salt, cosurfactant, and sometimes oil in addition to the major surfactant. The concentration and/or type of each component can alter the rheological behavior of these surfactant systems. Two types of water soluble polymers are available for mobility control in field application. Again, polymer type, polymer concentration, and salt concentration affect flow behavior. Data are presented to show the effects chemical composition and shear rate have on the rheological properties of chemical formulations useful in enhanced oil recovery operations.

ISSN:0148-6055    

DOI:10.1122/1.549525

出版商:The Society of Rheology    

年代:1979

数据来源: AIP

摘要:

A theory for stress relaxation is presented which applies when crazing is the mode of relaxation. The theory is in terms of the microparameters of crazing, which are the density, size, shape, and velocity of the crazes. The stress‐relaxation curves of polystyrene, polymethylmethacrylate, and polycarbonate were measured in nitrogen and helium environments at 77 K. PS and PMMA stress relaxed only inN2,which causes crazing. The PC stress relaxed inN2and He. The experimental stress‐relaxation curves from crazing agreed with the theoretical equation and the experimental curves were shown to be predictable in terms of the microparameters of crazing.

ISSN:0148-6055    

DOI:10.1122/1.549536

出版商:The Society of Rheology    

年代:1979

数据来源: AIP

摘要:

The contributions to a seminar on the Continuum Mechanical and Statistical Approaches in the Mechanics of Granular Materials are briefly summarized and future trends in understanding the mechanical behavior of granular material are suggested.

ISSN:0148-6055    

DOI:10.1122/1.549526

出版商:The Society of Rheology    

年代:1979

数据来源: AIP

ISSN:0148-6055    

DOI:10.1122/1.549552

出版商:The Society of Rheology    

年代:1979

数据来源: AIP