Fluid systems media

The principle of operation of the hydraulic reciprocating pump is similar to the beam pump, with a piston-like sub-surface pump action. The energy to drive the pump, however, is delivered through a hydraulic medium, the power fluid, commonly oil or water. The power fluid drives a downhole hydraulic motor which in turn drives the pump. A separate surface pump delivers the hydraulic power. The power fluid system can be of the closed loop or of the open type. In the latter case, the power fluids are mixed with the produced fluid stream. The performance of the hydraulic pump is primarily monitored by measuring the discharge pressures of both surface and sub-surface pumps. 

Slurry Pipelines. Finely divided soHds can be transported in pipelines as slurries, using water or another stable Hquid as the suspending medium. Flow characteristics of slurries in pipelines depend on the state of subdivision of the soHds and their distribution within the fluid system. 

The relationship between V0, the LNAPL volume, and Ha, the apparent thickness of LNAPL in the observation well, is unique, nonlinear, and dependent on the particular porous medium/fluid system. 

Figure 6 Jablonski diagram illustrating the eT process from the M subunit to the photo-excited FI subunit in a covalently linked two-component system F1 M. In a fluid polar medium, the FP IVT ion pair which form is stabilized by the interactions with solvent molecules and the eT process is thermodynamically favoured. If solvent molecules are immobilized, the FI M ion pair is not stabilized by solute-solvent interactions and its energy is higher than that of the photo-excited system FI M this prevents the occurrence of the eT process.

The other term in Eq. III. 10 contains contributions to the average force due only to the polarization of a region around the point R of dimensions of the order of the correlation length in the medium. For most fluid systems, this length will be sufficiently small so that this term may be considered as a short-range contribution to the force. This is also the case for the last term of Eq. 1II.7 which contains a contribution proportional to an inverse power of the interatomic distance higher than 4 due to the correlation between dipole moments of different atoms. (In practice the power of the interatomic distance will be at least —7.)... 

The distribution of these primary species and their eventual fate is determined by the nature and state of the medium. If the viscosity is extremely high as in solids or glasses, the distribution remains nonuniform and the reactions that occur involve species within the same, or closely related, spur. If the viscosity is low, such as in a fluid system, these species tend to diffuse apart and lead to a uniform distribution throughout the medium. In this case, the reactions conform to kinetic laws for a homogeneous system. 

The principles of conservation of momentum, energy, mass, and charge are used to define the state of a real-fluid system quantitatively. The conservation laws are applied, with the assumption that the fluid is a continuum. The conservation equations expressing these laws are, by themselves, insufficient to uniquely define the system, and statements on the material behavior are also required. Such statements are termed constitutive relations, examples of which are Newton s law that the stress in a fluid is proportional to the rate of strain, Fourier s law that the heat transfer rate is proportional to the temperature gradient. Pick s law that mass transfer is proportional to the concentration gradient, and Ohm s law that the current in a conducting medium is proportional to the applied electric field. 

When AT effects dominate, the response can further be complicated when the heating medium is a circulating fluid. A chaise in reboiler heat duty may significemtly affect the overall heat load on the circulating fluid system. Unless the system temperature is well-dampened or tightly controlled (this may not always be achievable), reboiler heat load... 

According to the Curie-Prigogine principle, vector and scalar quantities interact only in an anisotropic medium. This principle as originally stated by Curie in 1908 is quantities whose tensorial characters differ by an odd number of ranks cannot interact in an isotropic medium. Consider a flow J,- with tensorial rank m. The value of m is zero for a scalar, it is unity for a vector, and it is two for a dyadic. If a conjugate force Xj also has a tensorial rank m, than the coefficient Ly is a scalar, and is consistent with the isotropic character of the system. The coefficients Ly are determined by the isotropic medium they need not vanish, and hence the flow J, and the force Xj can interact or couple. If a force Xj has a tensorial rank different from m by an even integer k, then Ly has a tensor at rank k. In this case, Lij Xj is a tensor product. Since a tensor coefficient Ly of even rank is also consistent with the isotropic character of the fluid system, the Ly is not zero, and hence J,- andXy can interact. However, for a force Xj whose tensorial rank differs from m by an odd integer k, Ly has a tensorial rank of k. A tensor coefficient Ly of odd rank implies an anisotropic character for the system. Consequently, such a coefficient vanishes for an isotropic system, and J, and Xj do not interact. For example, if k is unity, then Ly would be a vector. 

Effect of porous medium on phase behavior. Several authors have studied the effect of the porous medium on the phase behavior of reservoir fluid systems. Russian authors Trebin and Zadora (1968) report a strong influence of the porous medium on the dewpoint pressure and vapor-liquid equilibrium (VLE) of gas condensate systems. The porous medium used by these authors was a silica sand mixture (0.300 to 0.215 mm diameter) ground by a special cutter-pulverizer. Three different packings with permeabilities of 5.6, 0.612, and 0.111 darcies and... 

Tindy and Raynal (1966) measured the bubblepoint pressure of two reservoir crude oils in both an open space (PVT cell) and a porous medium with grain sizes in the range of 160 to 200 microns. The bubble-point pressures of those two crude oils were higher in the porous medium than in a PVT cell by 7 and 4 kg/cm, respectively. Specifically, the bubblepoint pressure of one of the two crude oils measured at 80 C in a PVT cell was 121 kg/cm and the bubblepoint pressure at the same temperature in a porous medium of 160 to 20 microns was 128 kg/cm. On the other hand, when these authors used a mixture of methane and n-heptane, they observed no differences in the saturation pressure. Sigmund et aL (1973) have also investigated the effect of the porous medium on phase behavior of model fluids. Their measurements on dewpoint and bubblepoint pressures showed no effect of the porous medium. The fluid systems used by these authors were Cj/nC. and Ci/nCs. The smallest bead size used was 30 to 40 U.S. mesh. In Example 2.3 presented at the end of this chapter, the effect of interface curvature on dewpoint pressure and equilibrium phase composition will be examined. 

The second type of hoUow-fiber module is the bore-side feed type illustrated in Figure 23b. The fibers in this type of unit are open at both ends, and the feed fluid is usually circulated through the bore of the fibers. To minimize pressure drops inside the fibers, the fibers often have larger diameters than the very fine fibers used in the shell-side feed system and are generally made by solution spinning. These so-called capillary fibers are used in ultrafiltration, pervaporation, and in some low to medium pressure gas appHcations. Feed pressures are usually limited to less than 1 MPa (150 psig) in this type of module. 

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