Main experimental drugs: 60# paraffin, methyl stearate polyoxyethylene ether, fatty acid methyl ester ethoxy sulfonate, surfactant, methanol, ethanol, n-butanol, sodium silicate.

Main experimental instruments: digital display constant temperature water bath pot, timing electric agitator, petroleum product freezing point tester, rotary viscometer self-assembly wax rate measuring device, wax prevention rate measuring device.

The schematic diagram of the measuring device is shown in Figure 1.

The formula for the rate of wax dissolution:

v = m / t (1)

v (g/min): Wax dissolution rate; m (g): Paraffin quality; t (min): Time required to dissolve paraffin.

First, the paraffin wax needed to be tested was dissolved and placed in the paraffin mold of device 6 to make it fully compatible with the mold. After cooling, the paraffin wax was taken out and weighed with electronic balance, and the paraffin quality was recorded accurately to 0.01 g. Then, the wax removal samples to be tested were added to the water temperature control in 50˚C ± 1˚C digital constant temperature water bath pot. After the wax removal samples were kept constant temperature, the paraffin wax was invaded into the wax removal samples and the time of complete dissolution of paraffin was recorded. Finally, the wax dissolution rate is calculated by the formula.

The schematic diagram of the measuring device is shown in Figure 2.

Wax proof formula:

n = [ ( m 1 − m 2 ) ÷ m 1 ] × 100 % (2)

n: Wax proof; m₁: Wax deposition without wax remover; m₂: Deposition with wax remover. The pump in the device is a magnetic pump, and two waxing tubes are placed in the waxing chamber as the test tube and reference tube of paraffin wax.

The test steps are as follows: first, two 500 ml beakers are added, 200 g of diesel oil and 50 g, of paraffin wax are added to dissolve , 50 g of ethanol and 50 minutes of distilled water are added, and the agitator is used to stir evenly for 15 minutes. Clean up the wax pipe and install it in the wax chamber. After that, two samples were added to the sample room, one of which was added to the SGJ-1 wax remover. The temperature of the sample chamber is stable at 45˚C ± 1˚C and the temperature of the waxing chamber is between 35˚C ± 1˚C. At the same time, the magnetic pump is opened and the sample is stirred evenly with agitator for 40 minutes. When the equipment is cooled to room temperature, the wax tube is removed and weighed. The accurate value is 0.01 g. The Record wax deposition without wax remover and SGJ-1 wax remover. Finally, the formula is brought into the calculation.

When the molar ratio of methyl stearate polyoxyethylene ether to fatty acid methyl ester ethoxylated sulfonate was 3:1, the wax dissolving dispersant was obtained. The wax dissolving rate of different doses of wax dissolving dispersant was measured in Table 1.

Surfactant can play a good wetting and inversion effect on paraffin wax, and can transform the waxing surface of oil well species into hydrophilic surface, which can not only remove wax, but also play the role of wax prevention. It is an indispensable part of water based wax cleaning and wax prevention agent [13] [14] [15]. Seven kinds of surfactants, such as Tween20, Tween80, JFC-2, CLD510, CLD-3P, OP-10, MOA-3B, were used to determine the wetting reversal agent. At the same time, according to the HLB value of the surfactant, the wetting reversal agent was obtained by compounding the JFC-2 and OP-10 molar ratio of 1:3. Determination the wax dissolution rate after adding different doses of wetting reversal agent is shown in Table 2.

As can be seen from this table, after the addition of wetting reversal agent containing wax dissolving dispersant, the rate of wax dissolving has not been obviously improved, which is because the HLB value of the selected surfactant is the main determinant of the surfactant ability or not.

When the molar ratio of methanol, ethanol and n-butanol was 3:2:1, the alcohol cosolvent was obtained. The wax dissolution rate of alcohol cosolvent with different doses was determined as shown in Table 3.

Sodium silicate, also known as vesic flower alkali, can not only adjust its acid and base, but also make the asphaltene of oil field wax more easily dispersed in water. Because some groups in asphaltene can change with alkali, many nuclei can be formed by wax, and these suspended nuclei can be taken away by the flow of crude oil, so as to achieve the purpose of dewaxing. When sodium silicate was added 0.5% - 2.0%, the water-based anti-wax agent was alkaline. The wax dissolution rate and PH value after adding different doses of sodium silicate were measured as shown in Table 4.

Through the data in Tables 1-4, we find that when the wax dissolution rate is determined after adding the components of water-based wax cleaning agent in turn, although with the addition of these four components, the wax dissolution rate has been slowly increased. But the effect is not particularly obvious. Finally, after adding sodium silicate, the water-based wax-cleaning agent has been weakly alkaline. Compared with the expensive material cost, it is not feasible to simply pursue the addition of four components to make the water-based wax-cleaning agent. Therefore, the following formula optimization experiments are carried out.

Orthogonal experiment was conducted with different dosage of dispersant, wetting reversion agent, alcohol cosolvent and sodium silicate as the factors, and the dispersant rate of wax as the index. Factor levels are shown in Table 5.

According to the orthogonal experiment in Table 6 and the data in Table 7, it can be seen that the factors affecting the wax dissolution rate of water-based paraffin repellent agent are A > D > B > C, from large to small.

The optimum formula for water-based anti-wax agent is A₃B₁C₁D₃, That is Solving wax dispersants: 15%; Wetting reversal agent: 1%; Sodium silicate: 1%; Alcohol cosolvent: 8%.

Coagulation point refers to the maximum temperature required when the liquid of water-based wax remover changes to the liquid level and does not move the solid. Generally speaking, in the field use process, the setting point of water-based wax remover should be lower than the minimum temperature in local winter. Therefore, the setting point of water-based wax remover is an important index to measure its quality. The results of the determination of condensation points of several water-based dewaxing agents using a petroleum product condensation point tester are shown in Figure 3.

Figure 3 shows that the setting temperature of each product of water-based wax remover meets the requirements of use, and the maximum temperature is minus 28˚C. The freezing point temperature of SGJ-1 products is up to minus 34˚C, which can meet the colder winter operations and cope with different climate changes in various places. The scope of application is wider.

Different viscosity of crude oil will make the velocity of crude oil different, and faster velocity of crude oil will lead to lighter waxing degree of crude oil, because faster velocity can reduce the time of crude oil in wellbore and slow down the oil temperature. Wax particles are taken away without more time to deposit in the cylinder wall. The permeability and dispersion of surfactants in water-based wax remover can penetrate into the wax crystal gap, weaken the binding ability of wax molecules, prevent the formation of wax blocks, the viscosity of crude oil is reduced and the fluidity of crude oil becomes stronger. In order to test the viscosity-reducing effect of water-based wax remover, the crude oil in Changqing Oilfield is taken as Sample, crude oil physical properties as shown in Table 8.

The curves of crude oil viscosity and crude oil viscosity measured at ˚C temperature of 20 to 50 are shown in Figure 4.

We can intuitively see from Figure 4 that the viscosity of crude oil after adding SGJ-1 is much lower than that of non-added crude oil. The difference between the two decreases from nearly 800 mPa∙s to almost 0 mPa∙s with the increase of temperature. Before the temperature is 35˚C, the water-based dewaxing agent can reduce the viscosity of crude oil, increase the ability of crude oil to carry wax molecules, and make the waxing ability of crude oil smaller.

The ability of wax dissolving is an important embodiment of the performance of water-based wax cleaning preservatives. We use the self-assembled wax dissolving device and formula to determine the wax dissolution rate of water-based wax cleaning preservatives. The data compared with other products in the same field are shown in Table 9.

Through Table 9, we found that in terms of wax dissolution rate, the wax dissolution rate SGJ-1, water-based wax cleaning agent developed by us reached 0.0512 g/min, and the wax dissolution ability was higher than that of other water-based wax removal agents in the same field. At the same time, the industry reference standard [20] 0.016 g/min, wax dissolution effect is very good.

Because crude oil contains a large number of paraffin components, when the oil temperature decreases below the wax analysis point in the production process, the paraffin will precipitate, resulting in wax formation. Water-based anti-waxing agent can effectively reduce paraffin precipitation in crude oil and achieve anti-wax effect. The anti-wax rate is also an efficiency to reduce the precipitation of crude oil paraffin after adding reagent. The higher the anti-wax rate, the better the effect. Test Formula for Wax Resistance in Formula (2).