RU2481375C1 - Hydrate growth inhibitor of kinetic action - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: hydrate growth inhibitor of kinetic action contains, wt %: a mixture of polyvinyl pirrolidone and polyvinyl kaprolaktam of different marks with molecular weight 6000-8000 g/mole at their molecular ratio 1 : (1 ±0.1) 10-20, hydrolysed polyacrylamide 0.1-1.0, ethanol containing solution - the rest.

EFFECT: increase of inhibiting ability in relation to hydrate formations at low inhibitor consumption.

5 ex, 1 tbl, 2 dwg

Description

The invention relates to the oil and gas industry and can be used for processing wells and pipelines in order to prevent the formation of hydrates in them.

It is known that to prevent hydrate formation in wells and pipelines, pure methanol is used (see WFD 39-1.13-051-2001. Instructions for rationing the rate and calculation of methanol emissions for Gazprom facilities).

However, this treatment requires large volumes of methanol poison, especially for heavily watered wells.

Closest to the claimed inhibitor and adopted as a prototype is a composition for inhibiting the formation and growth of gas hydrates, containing at least one kinetic inhibitor of hydrate formation of low concentration and at least one thermodynamic inhibitor of hydrate formation. A kinetic inhibitor of hydrate formation includes aminated polyalkylene glycols represented by the formula R ₁ R ₂ N [(A) a- (B) b- (A) c- (CH ₂ ) d-CH (R) -NR ₁ ] nR ₂ (I) , wherein:

- each A is independently selected from —CH ₂ CH (CH ₃ ) O— or —CH (CH ₃ ) CH ₂ O—;

- B is -CH ₂ CH ₂ O-;

- a + b + c from 1 to about 100;

- R is —H or —CH ₃ ;

- each R ₁ and R _{2 are} independently selected from the group consisting of —H, —CH ₃ , —H ₂ CH ₂ OH, and —CH (CH ₃ ) CH ₂ O;

d from 1 to about 6;

- n from 1 to about 4 (see patent CA No. 2506925, IPC ЕВВ 43/12, ЕВВ 43/22, publ. 05.10.2006).

The disadvantages of this composition are the complexity of its synthesis, the instability of the kinetic parameters for different batches, which requires additional laboratory studies, a relatively low maximum supercooling temperature and a high required concentration. As a thermodynamic inhibitor, toxic methanol is used.

The objective of the invention is the creation of an inhibitor of hydrate formation of kinetic action (hereinafter - IHD), which has an increased inhibitory ability against hydrate formation at its low consumption.

The problem in IGKD, which includes a low molecular weight polymer and a solvent, is solved by the fact that it additionally contains hydrolyzed polyacrylamide (PAA), a mixture of polyvinylpyrrolidone (PVP) and polyvinylcaprolactam (PVAcap) of various grades with a molecular weight of 6000-8000 is used as a low molecular weight polymer when their molar ratio is 1: (1 ± 0.1), an ethanol-containing solution is used as a solvent in the following ratio of components, wt.%:

- a mixture of PVP and PVKap of different grades with a molecular weight of 6000-8000 g / mol with a molar ratio of 1: (1 ± 0.1) - 10-20; - hydrolyzed PAA - 0.1-1.0; - ethanol-containing solution - the rest

In order to realize the purpose of the claimed inhibitor as the ethanol-containing solution, the head fraction of the ethanol rectification column (ether-aldehyde fraction) is used.

A mixture of PVP and PVKap of different grades with a molecular weight of 6000-8000 g / mol with their molar ratio of 1: (1 ± 0.1) provides an increase in the hydration induction period to the required time of 10-15 minutes.

Hydrolyzed PAA provides an increase in supercooling temperature to 10-12 ° C, since it is a polyelectrolyte, that is, a polymer whose molecules include groups capable of ionization in solution. Polyelectrolytes are used in technology as coagulants for wastewater treatment, as dispersants to reduce the viscosity of highly concentrated dispersed water-based systems (suspensions and pastes in the manufacture of ceramics). The effectiveness of polyelectrolytes in these applications is explained by the adsorption of polyions on the surface of particles with the formation of a double electric layer that effectively reduces friction between particles (see, for example, A.R. Khokhlov. Susceptible gels. - Soros Educational Journal, 1998, No. 11, p.138 -142).

The ethanol-containing solution ensures the stability of the inhibitor at low ambient temperatures and its delivery to the point of hydrate formation.

The effectiveness of IGKD was evaluated by the time of the induction period of increasing pressure in a laboratory setup for the formation of propane hydrate. The data of this assessment are tabulated and confirmed by figures 1 and 2.

Table The results of laboratory studies of the claimed composition and prototype for inhibitory ability Solution Concentration in water,% Maximum subcooling, ° С The average time of the induction period, min one 0.05 10 10-15 2 0.1 10.5 10-15 3 0.2 eleven 15-17 four 0.5 7.5 10-12 5 0.5 6 10-15 Proto
type of one 6 5-15 Analogue fifteen 10* Does not freeze * Lowering freezing temperature

The dependence of the temperature of hydrate formation at various contents of hydrolyzed PAA (polyelectrolyte) is shown in figure 1. As can be seen from the graph in figure 1, already at a concentration of 0.1% polyelectrolyte reduces the temperature of hydrate formation by 10 ° C. However, its concentration above 1% should not be created due to the absence of a significant temperature change.

Figure 2 shows the dependence of the induction period on the concentration of the solution. As can be seen from the indicated dependence, the inhibitor is effective at concentrations from 0.01 to 5% in water.

IGKD is prepared by simply mixing the calculated amounts of the components in a separate container. First, solutions of PVP and PVKap are mixed with a molecular weight of 6000-8000 g / mol at a molar ratio of 1: (1 ± 0.1), then hydrolyzed PAA is added and the ethanol-containing solution is adjusted to the required mass. All mix thoroughly for 15 minutes.

Example 1. To 10 wt.% Ethanol-containing solution add 10 wt.% N-vinyl-2-pyrrolidone, 9.9 wt.% N-vinyl-2-caprolactam (M.m. = 6000), 1 wt.% Hydrolyzed PAA (M.m. = 6000), bring the ethanol-containing solution to 100 wt.%. All mix thoroughly for 15 minutes.

Example 2. To 5 wt.% Ethanol-containing solution add 5 wt.% N-vinyl-2-pyrrolidone (M.M. = 8000), 5.05 wt.% N-vinyl-2-caprolactam (M.M. = 8000), 0.1 wt.% Hydrolyzed PAA, adjusted with ethanol-containing solution to 100 wt.%. All mix thoroughly for 15 minutes.

Example 3. To 8 wt.% Ethanol-containing solution add 7 wt.% N-vinyl-2-pyrrolidone (M.M. = 6000), 7 wt.% N-vinyl-2-caprolactam (M.M. = 6000) , 0.5 wt.% Hydrolyzed PAA, bring ethanol-containing solution to 100 wt.%. All mix thoroughly for 15 minutes.

Example 4. To 8 wt.% Ethanol-containing solution add 7 wt.% N-vinyl-2-pyrrolidone (M.M. = 2000), 7 wt.% N-vinyl-2-caprolactam (M.M. = 2000) , 0.5 wt.% Hydrolyzed PAA is adjusted with an ethanol-containing solution to 100 wt.%. All mix thoroughly for 15 minutes.

Example 5. To 8 wt.% Ethanol-containing solution add 7 wt.% N-vinyl-2-pyrrolidone (M.M. = 10000), 7 wt.% N-vinyl-2-caprolactam (M.M. = 10000) , 0.5 wt.% Hydrolyzed PAA, bring ethanol-containing solution to 100 wt.%. All mix thoroughly for 15 minutes.

The results of laboratory studies showed that the claimed IGKD in comparison with the prototype has a better inhibitory ability and works effectively at lower contents.

Claims (1)

A kinetic action hydrate inhibitor, including a low molecular weight polymer and a solvent, characterized in that it additionally contains hydrolyzed polyacrylamide - PAA, a mixture of polyvinylpyrrolidone - PVP and polyvinylcaprolactam - PVCKap of different grades with a molecular weight of 6000–8000 with a molecular weight of 6000–8000 is used as a low molecular weight polymer. 1: (1 ± 0.1) ratio, an ethanol-containing solution is used as a solvent in the following ratio of components, wt.%:
a mixture of PVP and PVKap of different grades with molecular weight 6000-8000 g / mol at their molar ratio 1: (1 ± 0.1) 10-20 hydrolyzed PAA 0.1-1.0 ethanol-containing solution rest

Images