Relative permeability injection effect

Conventionally, the sample is initially saturated with one fluid phase, perhaps including the other phase at the irreducible saturation. The second fluid phase is injected at a constant flow rate. The pressure drop and cumulative production are measured. A relatively high flow velocity is used to try to negate capillary pressure effects, so as to simplify the associated estimation problem. However, as relative permeability functions depend on capillary number, these functions should be determined under the conditions characteristic of reservoir or aquifer conditions [33]. Under these conditions, capillary pressure effects are important, and should be included within the mathematical model of the experiment used to obtain property estimates. 

Blends of sodium hypochlorite with 15% HC1 and with 12% HCl/3% HF have been used to stimulate aqueous fluid injection wells(143). Waterflood injection wells have also been stimulated by injecting linear alcohol propoxyethoxysulfate salts in the absence of any acid (144). The oil near the well bore is mobilized thus increasing the relative permeability of the rock to water (145). Temperature effects on interfacial tension and on surfactant solubility can be a critical factor in surfactant selection for this application (146). 

As defined by Radke and Ransohoff (Equation 7), the "snap-off" capillary number, C, contains the effective grain radius, R the permeability, K anS the relative permeability of the nonwetting phase, k ( ). In field applications, the values of all of these parameters are set by the reservoir. Also contained in C are the total superficial velocity, U, and the distance between injection and production wells, L. Within narrow limits, L can be changed by... 

The emulsification properties of the crude oil must be determined. Some crude oils can be emulsified with surfactant mixtures, others with caustic. Some crudes, such as Hasley Canyon (Table III), are difficult to emulsify. Experiments can be performed to determine if in situ emulsification is feasible, or if an emulsion must be injected. If in situ emulsification is feasible, loss of chemicals to reservoir rock is a problem to be addressed. If in situ emulsification is employed in conjunction with steam, it must be determined if chemicals are most effective when injected with the flowing steam or when chemical/steam injections are alternated. Relative permeabilities of the injected fluids should be determined. All of this information is needed to calculate the economics of scale-up to a specific field situation. 

Our first task is to evaluate the validity of the conventional concept about the mobility control requirement using a simulation approach. This model uses the UTCHEM-9.0 simulator (2000). The dimensions of the two-dimensional XZ cross-section model are 300 ft x 1 ft x 10 ft. One injection well and one production well are at the two extreme ends in the X direction, and they are fully penetrated. The injection velocity is 1 ft/day the initial water saturation and oil saturation are 0.5. The displacing fluid is a polymer solution. The purpose of using the polymer solutuion in the model is to change the viscosity of the displacing fluid. Therefore, polymer adsorption, shear dilution effect, and so on are not included in the model. To simplify the problem, it is assumed that the oil and water densities are the same that the capillary pressure is not included that the relative permeabilities of water and oil are straight lines with the connate water saturation and residual oil saturation equal to 0 and that the water and oil viscosity is 1 mPa s. Under these assumptions and conditions, we can know the fluid mobilities at any saturation. The model uses an isotropic permeability of 10 mD. 

TABLE 7.11 Effect of Surfactant Injection on Relative Permeabilities ... 

A 0.1% selected surfactant was then added to the injection water. The core flood experiments showed that injection pressure was reduced by 26.6%, and that the oil recovery was increased by 6.7%. This effect was a result of wettability alteration to more water-wet, reduced immobile water and oil saturations, and increased oil and water relative permeabilities. The data are shown in Table 7.11. 

Effect of Relative Permeabilities (kr Curves) in Continuous Injection of Surfactant... 

Table 1 gives a information about influence of polymer and surfactant concentrations on the main parameters of mathematical model of oil displacement process by polymer and surfactant solutions. The table shows that both polymer and surfactant effect viscosities of the both phases and do not effect the relative permeabilities. Capillary pressure takes into account the influence of surfactant concentration and the absolute permeability of rock decreases during injection of the polymer. 

Figure 8.1. The effect of mobility ratio on the in-situ saturation profile in a linear waterflood after 0.2 pv of injection relative permeabilities of the form in Table 8.1 with = 0.25, S c ...

Consider the effect of adding sufficient polymer to the injected water so that the apparent viscosity of the polymer solution is 4 cp. Assume that no reduction in water relative permeability is caused by the polymer. The mobility ratio, Mg, would be expected to decrease by a factor of four to about 0.54, which is clearly favorable. In Example 3.5, the displacement performance of a polymer flood was estimated for a polymer solution containing 300 ppm polymer with an apparent viscosity of 4.0 cp. Retention is 17.5 /tg/g at 300 ppm, so that Dp =0.424. Effective inaccessible PV for this system is estimated to be 0.25. Thus, —< g+Z>p =0.174. 

Design procedures included laboratory tests on polymer rheology, relative permeability, shear degradation, screen factor, stability, and salinity effects. Computer simulations were performed to predict recoveries and to examine optimum polymer concentration. Field injectivity tests were conducted to examine injectivity behavior with time and to gain experience in surface handling of the polymer. Pressure-falloff tests were conducted in conjunction wiA the injectivity tests. Finally, the prqiamtion involved design of the polymer-injection plant and analysis of costs. 

The RUI method is a modification of the brain uptake index method [29] which was first described by Aim and Tornquist [4], The RUI approach consists of a single-arterial (e.g., intracarotid) injection technique, where the primary objective is to analyze the influx of the test substrate from the circulating blood to the retina through the BRB (i.e., blood-to-retina direction). This approach, for example, has been used to determine the retinal uptake of the test substrate which has a relatively high permeability across the BRB. The advantage of this approach is that it avoids the effect of plasma-protein binding of the test substrate and allows the retinal uptake of the test substrate... 

HT is relatively more potent than histamine in increasing vascular permeability in the rat [61, 137, 414, 485, 487, 534, 578, 581]. Parratt and West [482-490] extensively studied the significance of the presence of the substantial amounts of both 5-HT and histamine in the skin and subcutaneous tissues of the rat, and the importance of their release from these sites during the anaphylactoid reaction. Polymyxin B sulphate released more than 90% of the histamine in the rat skin but less than 20% of its 5-HT on the other hand, reserpine released more than 90% of the 5-HT but only small amounts of the histamine. Pretreatment with reserpine, but not with polymyxin B sulphate, effectively inhibited both the egg-white and dextran anaphylactoid reaction. Further evidence for an important role of 5-HT in the anaphylactoid reaction was obtained when it was found that after an intraperitoneal injection of egg-white or dextran 5-HT, but not histamine, was present in the oedema fluid associated with the subcutaneous tissues on the dorsal side of the foot. 

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