Oscillatory flow

To remove filter-cake, a physical method can be applied wherein a fluid is oscillated in the annulus prior to cementing [948,949]. The direction of flow of the fluid in the annulus is changed at least twice. The oscillatory flow of the fluid removes the drilling mud and the filter-cake from the annulus. After this oscillatory flow treatment, the cement slurry is pumped into the annulus. 

Squeeze Cementing. Squeeze cementing is used for the following purposes  

The slurry should be designed to allow the fluid loss of the formation to be squeezed into the respective formation. Low-permeability formations can have a formulation of the slurry with an American Petroleum Institute (API) fluid loss [68] of 100 to 200 ml/30 min, whereas high-permeability formations 

Thick slurries will not fill a narrow channel well. Therefore squeeze cement slurries should be rather thin. Dispersants should be added for this reason. High compressive strength is not necessary for these types of slurries. 

Often in open-hole completion operations and in production, it is necessary to shut off water flows. Additional cementation methods are used to provide an anchor for testing tools or for other maintenance operations. 

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Oscillatory Flow Meters. Three different oscillatory fluid phenomena are used in flow measurement. 

Fig. 14. Cross sections of oscillatory flow meters (a) fluidic, where (—fc.) represents the main flow and (-...

The above description refers to a Lagrangian frame of reference in which the movement of the particle is followed along its trajectory. Instead of having a steady flow, it is possible to modulate the flow, for example sinusoidally as a function of time. At sufficiently high frequency, the molecular coil deformation will be dephased from the strain rate and the flow becomes transient even with a stagnant flow geometry. Oscillatory flow birefringence has been measured in simple shear and corresponds to some kind of frequency analysis of the flow... 

In order to observe any temperature dependence in transient flow degradation, it would be necessary to prolong considerably the effective residence time of the polymer coil. This can be accomplished either by recirculating the solution or by using an oscillatory flow equipment as described in Sect. 4.1 (Figs. 23 and 24). 

A steady-state solution of Eq. (3.30) exists only for < 2. At z > 2 hydrodynamic thermal explosion occurs and oscillatory flow takes place. 

Under certain conditions the energy dissipation may lead to an oscillatory regime of laminar flow in micro-channels. The oscillatory flow regime occurs in microchannels at Reynolds numbers less that Recr- In this case the existence of velocity flucmations does not indicate change from laminar to turbulent flow. 

Ozawa M, Akagawa K, Sakaguchi T, Tsukahara T, Fuji T (1979) Oscillatory flow instabilities in air-water two-phase flow systems. Report. Pressure drop oscillation. Bull JSME 22 1763-1770 Qu W, Yoon S-M, Mudawar 1 (2004) Two-phase flow and heat transfer in rectangular microchannels. J Electron Packag 126 288-300... 

S. R. Keller. Oscillatory flow method for improved well cementing. Patent CA 1225018, 1987. 

Data for the bulk fluid, line A, indicate that vz varies as a function of z but maintains a value near 0.75 of maximum velocity. The periodicity of vx and vy is clearly evident in the graph of line A and a 1800 out of phase coupling of the components is seen with one positive when the other is negative. This indicates a preferred orientation to the plane of the oscillatory flow and this feature was seen in all the biofilms grown throughout this study. The secondary flow components are 0.1-0.2 of the maximum axial velocity and are spatially oscillatory. The significant non-axial velocities indicate non-axial mass transport has gone from diffusion dominated, Pe = 0, in the clean capillary, to advection dominated, Pe 2 x 103, due to the impact of the biofilm. For comparison, the axial Peclet number is Pe L 2x 10s. Line B intersects areas covered by biomass and areas of only bulk... 

The phase angle changes with frequency and this is shown in Figure 4.7. As the frequency increases the sample becomes more elastic. Thus the phase difference between the stress and the strain reduces. There is an important feature that we can obtain from the dynamic response of a viscoelastic model and that is the dynamic viscosity. In oscillatory flow there is an analogue to the viscosity measured in continuous shear flow. We can illustrate this by considering the relationship between the stress and the strain. This defines the complex modulus ... 

Lakin, M. B. Oscillatory Flow Simulation in an Idealized Bifurcation. Ph.D. Thesis. Denver University of Denver. 1973. 223 pp. 

A careful analysis of the current portfolio of one major pharmaceutical company indicates that about 60% of the chemistry is suitable for continuous processing. About 50% of this chemistry is homogeneous and therefore readily transferable to existing continuous processing technology. The remaining 50% is heterogeneous and will therefore require implementation of some of the current advances in continuous flow equipment such as oscillatory flow reactors [13]. Technically, the transfer of these processes from batch to continuous could happen within... 

Before leaving this discussion, it is important to note that other forms of Peclet numbers are also possible and may be more appropriate depending on the type of convective influence studied. For example, in the case of oscillatory flows (as in oscillatory viscometers), it is more useful to define the Peclet number as (Rfa/D), where co is the frequency of oscillation. Regardless of the particular definition, the general significance of the Peclet number remains the same, i.e., it compares the effect of convection relative to diffusion. 

Fig. 2.5. Steady-state and dynamic oscillatory flow measurements on a 2 wt. per cent solution of polystyrene S 111 in Aroclor 1248 according to Philippoff (57). ( ) steady shear viscosity (a) dynamic viscosity tj, ( ) cot 1% from flow birefringence, (A) cot <5 from dynamic measurements, all at 25° C. (o) cot 8 from dynamic measurements at 5° C. Steady-state flow properties as functions of shear rate q, dynamic properties as functions of angular frequency m. Shift factor aT which is equal to unity for 25° C, is explained in the text, cot 2 % and cot 8 are expressed in terms of shear (see eqs. 2.11 and 2.22)...

In section 4.7, the Onuki-Doi theory for form birefringence and dichroism was developed and presented in equations (4.91) and (4.92). It is left to calculate the structure factor, S (q), as a function of flow. This was done in the limit of weak oscillatory flow for the... 

Issa, M., Wang, M., Vilar, G. and Williams, R. A., Measurements using high speed EIT on an oscillatory flow reactor 3rd International Tomography Workshop Japan, Tokyo, May... 

E. B. Christiansen and W. R. Leppard, Steady-State and Oscillatory Flow Properties of Polymer Solutions, Trans. Soc. Rheol., 18, 65-86 (1974). 

Wen and Fan [6] have provided a comprehensive listing of various tracers and experimental techniques for determining the RTD in flow systems. Recent studies [10,11,12] have been performed employing an impulse tracer to determine the RTD in bubble columns and an oscillatory flow electrochemical reactor. The author [13,14] has employed both step-change and an impulse to determine the RTD of nozzle type reactors analysis of the RTD involves an atomic absorption spectrophotometer (AAS), a cine-projector, and a chart recorder. Figures 8-7 and 8-8 show the nozzle-type reactors and the AAS, respectively. Figure 8-9 gives a typical response curve from the AAS. 

Kraus et al. (74,75) studied the steady flow and oscillatory flow behavior of linear triblocks of S-B-S and B-S-B and radial block copolymers of the type (B-S-) 3, (S-B-)3, and (S-B-)4. For block copolymers of the same molecular weight and composition, those with end blocks of PS always have higher viscosities. However, when compared with corresponding linear block copolymers, the viscosities of the radial block copolymers are generally lower. 

The conclusion is that Lodge s rheological constitutive equation results in relationships between steady shear and oscillatory experiments. The limits y0 0 (i.e. small deformation amplitudes in oscillatory flow) and q >0 (i.e. small shear rates) do not come from Lodge s equation but they are in agreement with practice. These interrelations between sinusoidal shear deformations and steady shear flow are called the relationships of Coleman and Markovitz. 

We have presented a thorough description and discussion about the molecular origin of the second kind (b) - bamboo like extrudate distortion - in the preceding Sect. 8. The present section is devoted to a specific illustration of the molecular origin of the type (a) distortion, i.e., sharkskin, which occurs in a range of stress/rate below the oscillatory flow or stick-slip transition, as indicated in Fig. 1. The next section will provide a brief discussion of the origin of the type (c), often spiral-like distortion. The macroscopic nature of the type (c) distortion was first discussed at least over 20 years ago [75]. Note that when the type (c) spiral distortion occurs on very fine length scales on the extrudate it can be and has sometimes been mistaken as sharkskin. 

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