2. Preparing a inverse emulsion.

Materials:

1. Diesel fuel

2. Oil-soluble surfactant –NEFTENOL NZ-40

3. 25% solution of calcium chloride

The technique of preparing universe emulsions is similar to the one described above. Using the syringe, inject with a minimum rate of mixing 3 ml of NEFTENOL NZ-40 to the porcelain mug with 27 ml of diesel fuel. After its dissolving start injecting 170 ml (85%) calcium chloride solution into the surfactant solution. Inject dispersed phase by portions, taking into consideration the features of the previous methodology. After the injection of the total amount of the diesel fuel, it is necessary to continue mixing for 10 minutes more, and then it is possible to start the emulsion analysis with the microscope. Sketch the pattern obtained.

The emulsions prepared in this way can be applied in the processes of oil recovery enhancement and as a non-filterable fluid for well killing operations.

3. The preparing of a multiple emulsion.

Materials:

1. 0,5% solution of polyacrylamide prepared in fresh water

2. inverse emulsion prepared as described in point 2.

Measure out 180 ml of the inverse emulsion with graduated cylinder and pour it out into the porcelain mug. With a minimum rate of mixing inject 20 ml of polyacrylamide solution into the emulsion composition and continue mixing for 5 minutes more, after that start the emulsion analysis with the microscope. Sketch the pattern obtained. The emulsion prepared in this way can be used as a high-efficient fluids for hydraulic fracturing, they have less friction pressure loss for than inverse emulsions and they are practically fully completely destructed in the reservoirs with the temperature of 40-60 C.

4. Preparing of a semiemulsion.

Materials:

1. 0.5% solution of polyacrylamide in fresh water;

2. Water soluble surfantant – NEONOL AF_9-12

3. Diesel fuel

Measure out with the cylinder 38 ml of 0.5% solution of polyacrylamide prepared in fresh water and pour it out into the porcelain mug. With a minimum rate of mixing (to avoid foaming), using the syringe, inject 2 ml of NEONOL AF9-12 into the polyacrylamide solution, and then after its dissolving, inject a hydrocarbon fluid – 160 ml (80% vol) diesel fuel into the solution. Follow the techniqul description (see point 1 and Notes) for obtaining a high-disperse emulsion. Diesel fuel is tj be injected by portions: a quarter of a total amount with a minimum rate of mixing and the remaining ¾ of the total amount – faster, approximately within 2-3 minutes. After the injection of the total amount of the diesel fuel it is necessary to continue mixing for 10 minutes more, and then it is possible to start the emulsion analysis with the help of microscope. Sketch a pattern obtained.

The emulsions obtained in this way can be used as high-efficient fluids for hydraulic fracturing of formation, since they have a low friction pressure loss and they are stable at the reservoir temperatures of 60-80 C.

Notes:

There are two opposite processes occurring during the reaction of disperse phase emulsification – dispersion and coalescence. It follows from the analysis of emulsification process that the more energy is spent during the emulsion formation, the more high-disperse system is formed.

When obtaining the emulsion it is reasonable to use as much as possible the physicochemical properties of the surfactant and a specific character of viscosity level increasing. Thus, during the period of adding a disperse phase into the surfactant solution, surface tension at the interface of the mixed fluids is minimal, since the concentration of surfactant is maximal. During this period the viscosity of the system is also minimal due to the low content of disperse phase. These two factors contribute to efficient mixing of the fluids, which are insoluble in each other, thus maximum dispersion of the injected fluid occurs and the smallest drops of dispersed phase are obtained, and high mixing rate prevents the coalescence of the drops obtained. With the subsequent injection of a disperse phase into the system, the extension of drops obtained occurs, as surfactant concentration in the system decreases. Thus viscosity of emulsion increases, and, on the one hand, this prevents from efficient mixing and crushing of the drops, but, on the other hand, this prevents from coalescence. Therefore, in the process of emulsification some (smaller) portion of disperse phase has to be injected slowly as a thin stream with intensive mixing. It is necessary for maximum drop crushing. The subsequent portions can be injected faster. If the dispersed phase is injected too fast, even continuous mixing at high speed will not allow obtaining a high-dispersed emulsion.