CN117143579B - A formulation and construction method of in-situ porous polymer jelly - Google Patents

Abstract

The present invention provides a formula and construction method of a porous jelly that can be spontaneously generated in an oil reservoir environment, and relates to the field of oilfield chemical technology. Among them, the porous jelly system is composed of a polymer main agent, a cross-linking agent, an auxiliary agent, an in-situ gas production additive A and an in-situ gas production additive B, an emulsifier, and low molecular hydrocarbons. Its preparation method includes: dissolving the in-situ gas production additive A in water, preparing an oil-external phase microemulsion by adding low molecular hydrocarbons and emulsifiers, and adding the auxiliary agent, polymer main agent, in-situ gas production additive B and a cross-linking agent to the microemulsion under high-speed stirring to prepare a multiple emulsion. The in-situ generated porous polymer jelly provided by the present invention is applicable to a 80-100°C formation environment, and generates a jelly system with interconnected pores in situ under oil reservoir conditions, with high jelly strength and incomplete plugging. Partial plugging of the high permeability layer can be achieved to avoid excessive plugging to damage the reservoir.

Description

A formulation and construction method of in-situ porous polymer jelly

Technical Field

The invention relates to the technical field of oilfield chemistry, and in particular to an in-situ generated porous polymer jelly system and a preparation method thereof.

Background technique

Most of my country's old oil fields have entered the high water content stage, and the economic benefits have been greatly reduced. In order to increase the recovery rate and improve the water content of the produced fluid, the use of profile control and water plugging methods to plug the high permeability layer, adjust the water absorption profile and improve the flow channel distribution is a common method in oil fields.

The polymer gel system has the characteristics of high plugging strength and good plugging effect, and is the most commonly used system for oil field plugging in my country. At present, there are many patents for polymer gel systems, which have been optimized from multiple aspects such as temperature resistance, salt resistance, and gel stability. For example, patent CN116333704A discloses a gel system and preparation method that can quickly gel under high temperature and high salt conditions. The system described in the patent is an improved phenolic gel system, which is suitable for oil reservoirs with a temperature of 150°C and a mineralization greater than 200,000 mg/L. Patent CN114634805A discloses a self-growing gel dispersion system suitable for low-permeability and dense reservoirs and its control method. Its main components are acrylamide/vinyl sulfonate/acrylamide methyl sulfonate polymers and cross-linking agents. The particle size of the gel system can be regulated by adding nano-enhancers. Patent CN111499797A discloses another high-temperature resistant and high-strength gel, which consists of acrylamide/2-acrylamide-2-methylpropanesulfonic acid. By adding initiators, crosslinkers and montmorillonite additives, high-strength plugging can be achieved. Patent CN113249102A discloses a slow crosslinking gel for medium- and high-temperature reservoir profile control and its preparation method. By adding stabilizers, accelerators, catalysts, etc., the acrylamide polymer gel system can be slowly gelled in medium- and high-temperature reservoirs (90-110°C). The gelling time is within 72-168 hours, and the gel strength is high and the stability is good.

Although the current polymer gel system has made great progress in various performance dimensions, if the gel system is over-plugged during the plugging process, it will also cause damage to the reservoir, making subsequent construction difficult. Therefore, preparing a porous gel that meets the strength requirements can achieve moderate and effective plugging of the formation and meet the needs of the reservoir.

Summary of the invention

In view of the deficiencies of the above-mentioned prior art, a polymer gel system with interconnected pores that is spontaneously generated in the formation is provided and a preparation method thereof is given to avoid reservoir damage caused by excessive plugging that may be caused during the plugging process. At the same time, the gel strength it has can also ensure the plugging adjustment, thereby increasing the reservoir sweep range and strengthening the matrix oil recovery effect. Among them, the spontaneously generated interconnected pores are brought about by the spontaneous gas production of the in-situ gas generating agent in the system during the gel formation process, and the applicable temperature range is higher than the cloud point of the non-ionic surfactant, resulting in a decrease in its solubility, while achieving the demulsification spontaneous gas production and polymer gel formation process, thereby obtaining the target gel.

In order to achieve the above object, the present invention provides an in-situ porous polymer jelly system; the jelly system consists of a polymer main agent, a crosslinking agent, in-situ gas generating additives A and B, auxiliary agents, emulsifiers, and low molecular weight hydrocarbons.

Preferably, the polymer main agent is acrylamide/AMPS copolymer with a molecular weight of 800w or more;

Preferably, the cross-linking agent is hexamethylenetetramine, hydroquinone and N,N-methylenebisacrylamide;

Preferably, the emulsifier is a combination of alkylphenol polyoxyethylene ether surfactant, betaine surfactant, span surfactant and sodium lauryl sulfate;

Preferably, the auxiliary agent is a combination of n-butanol and hexylene glycol, and the combination ratio is 1:1 to 3:1;

Preferably, the in-situ gas generating additives are nitrous acid (additive A) and urea (additive B);

Preferably, the low molecular weight hydrocarbon is a combination of diesel and n-dodecane, with a combination ratio of 1:1 to 7:1;

A second aspect of the present invention provides a method for preparing an in-situ generated porous jelly system, the method comprising the following steps:

(1) adding the in-situ gas generating additive A into water and stirring evenly to obtain a water phase A;

(2) mixing the aqueous phase A and the oil phase in the required proportion, adding an auxiliary agent and an emulsifier, and stirring evenly to prepare an oil-external phase microemulsion;

(3) adding the in-situ gas generating additive B and the polymer main agent into water and stirring to obtain an aqueous phase B;

(4) adding the oil external phase microemulsion and the crosslinking agent into the aqueous phase B under high-speed stirring to prepare a multiple emulsion;

(5) The multiple emulsions are heated to form a gel, thereby obtaining an in-situ porous polymer gel system.

Preferably, in step (1), the amount of the in-situ gas generating additive A is 10% to 30%, and the stirring rate is 200 r/min to 500 r/min.

Preferably, in step (2), the oil-water ratio is 2:1-8:1; the emulsifier and auxiliary agent ratio is 2:1-4:1; the total concentration of the emulsifier and auxiliary agent is 20%-50%; the stirring speed is 200r/min-400r/min, and the stirring time is greater than 30 minutes.

Preferably, in step (3), the amount of the in-situ gas generating additive B is 7% to 45%; the amount of the polymer main agent is 1% to 8.5%.

Preferably, in step (4), the amount of the cross-linking agent is 0.3% to 1%, and the amount of the microemulsion is 20% to 50%.

Preferably, in step (4), the crosslinking agent should be added first, stirred at a low speed (200 r/min to 500 r/min) for 1 to 5 min, and then the microemulsion should be added and stirred at a high speed (1000 r/min to 3000 r/min) for 1 to 5 min.

Preferably, in step (5), the heating temperature is 85°C to 95°C.

Compared with the prior art methods, the advantages of the present invention are as follows:

(1) The in-situ autogenous porous gel system of the present invention generates interconnected pores when the gel is spontaneously gelled in the formation, so that the gel does not completely block the high-permeability reservoir, but only partially blocks it. This avoids excessive blocking caused by factors such as construction and the type of reagents, avoids reservoir pollution, and protects the reservoir's fluid production capacity.

(2) The in-situ autogenous porous gel system described in the present invention can achieve spontaneous gas production in the formation. The generation of gas can produce a foam-like system, further improving the heterogeneity of the reservoir.

(3) The emulsifier, additive, low molecular weight hydrocarbon and other components contained in the in-situ autogenous porous gel system described in the present invention can produce dilution and emulsification oil carrying effects with crude oil, play a role in improving the oil washing efficiency in the matrix, achieve efficient displacement, and further improve the recovery rate.

(4) The system described in the present invention is simple to prepare and can maintain stability for a long time after preparation, which can effectively simplify production and transportation.

Detailed ways

The following is an explanation of the embodiments of the present invention by specific examples. Those skilled in the art can easily understand the advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be applied from different viewpoints, and various modifications or changes can be made without departing from the spirit of the present invention. Before further describing the specific embodiments of the present invention, it should be understood that the scope of protection of the present invention is not limited to the specific specific embodiments described below; it should also be understood that the terms used in the examples of the present invention are intended to describe specific specific embodiments rather than to limit the scope of protection of the present invention. When the examples give a numerical range, it should be understood that, unless otherwise specified in the present invention, each numerical range endpoint and any internal numerical value can be selected.

Unless otherwise defined, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs. It is worth noting that the raw materials mentioned in the present invention are all commercially available common raw materials, and the sources are not specifically limited.

Embodiment 1:

The raw materials of the gel system are: polyacrylamide, hexamethylenetetramine, hydroquinone, Span80, SDS, OP-10, n-butanol, n-dodecane, nitrous acid and urea.

The specific preparation steps are:

(1) Weigh 30 g of nitrous acid and add it into 70 mL of water, stirring at 200 r/min for 3 min to obtain aqueous phase A;

(2) Weigh 20 mL of aqueous phase A and 50 mL of n-dodecane into a beaker, stir at 300 r/min for 1 min, then weigh 5.31 g of Span80, 3.55 g of SDS, 1.15 g of OP-10 and 4.92 g of n-butanol into the beaker, and continue stirring at the same speed for 5 min to obtain an oil-external phase microemulsion;

(3) Weigh 5 g of urea and 1 g of polymer, add them into water and stir for 60 min at a stirring speed of 300 r/min to obtain aqueous phase B;

(4) Weigh 0.3 g of urotropine and 0.3 g of hydroquinone and add them to 80 mL of aqueous phase B, and stir at 300 r/min for 3 min; then weigh 20 g of microemulsion and add it to aqueous phase B, and stir at 1500 r/min for 5 min;

(5) Pour the jelly system into a vial, seal it, and place it at 80°C to gel.

Embodiment 2:

The raw materials of the gel system are: polyacrylamide/2-acrylamido-2-methylpropanesulfonic acid, urotropine, N,N-methylenebisacrylamide, hydroquinone, Span80, SDS, oleyl amide allyl betaine, hexanediol, diesel, n-dodecane, nitrous acid, and urea.

The specific preparation steps are:

(1) Weigh 30 g of nitrous acid and add it to 70 mL of water, stirring at 200 r/min for 3 min to obtain aqueous phase A;

(2) Weigh 20 mL of aqueous phase A, 10 mL of diesel and 40 mL of n-dodecane into a beaker, stir at 300 r/min for 1 min, then weigh 3.78 g of Span80, 2.19 g of SDS, 2.31 g of oleyl amide allyl betaine and 5.63 g of hexanediol into the beaker, and continue stirring at the same speed for 5 min to obtain an oil-external phase microemulsion;

(3) Weigh 5 g of urea and 1 g of polymer, add them into water and stir for 60 min at a stirring speed of 300 r/min to obtain aqueous phase B;

(4) Weigh 0.3 g of urotropine, 0.3 g of hydroquinone and 0.2 g of N,N-methylenebisacrylamide and add them to 80 mL of aqueous phase B, and stir at 300 r/min for 3 min; then weigh 20 g of microemulsion and add it to aqueous phase B, and stir at 1500 r/min for 5 min;

(5) Pour the jelly system into a vial, seal it, and place it at 90°C to gel.

Embodiment 3:

The raw materials of the gel system are: polyacrylamide/2-acrylamido-2-methylpropanesulfonic acid, urotropine, N,N-methylenebisacrylamide, hydroquinone, Span80, SDS, hexanediol, diesel, n-dodecane, nitrous acid, and urea.

The specific preparation steps are:

(1) Weigh 30 g of nitrous acid and add it into 70 mL of water, stirring at 200 r/min for 3 min to obtain aqueous phase A;

(2) Weigh 20 mL of aqueous phase A, 10 mL of diesel and 40 mL of n-dodecane into a beaker, stir at 300 r/min for 1 min, then weigh 6.26 g of Span80, 4.19 g of SDS and 4.48 g of hexanediol into the beaker, and continue stirring at the same speed for 5 min to obtain an oil-external phase microemulsion;

(3) Weigh 5 g of urea and 1 g of polymer, add them into water and stir for 60 min at a stirring speed of 300 r/min to obtain aqueous phase B;

(4) Weigh 0.3 g of urotropine, 0.3 g of hydroquinone and 0.2 g of N,N-methylenebisacrylamide and add them to 80 mL of aqueous phase B, and stir at 300 r/min for 3 min; then weigh 20 g of microemulsion and add it to aqueous phase B, and stir at 1500 r/min for 5 min;

(5) Pour the jelly system into a vial, seal it, and place it at 100°C to gel.

Embodiment 4:

The raw materials of the gel system are: polyacrylamide, hexamethylenetetramine, hydroquinone, Span80, SDS, OP-10, n-butanol, n-dodecane, nitrous acid and urea.

The specific preparation steps are:

(1) Weigh 30 g of nitrous acid and add it into 70 mL of water, stirring at 200 r/min for 3 min to obtain aqueous phase A;

(2) Weigh 20 mL of aqueous phase A and 50 mL of n-dodecane into a beaker, stir at 300 r/min for 1 min, then weigh 5.31 g of Span80, 3.55 g of SDS, 1.15 g of OP-10 and 4.92 g of n-butanol into the beaker, and continue stirring at the same speed for 5 min to obtain an oil-external phase microemulsion;

(3) Weigh 5 g of urea and 1 g of polymer, add them into water and stir for 60 min at a stirring speed of 300 r/min to obtain aqueous phase B;

(4) Weigh 0.3 g of urotropine and 0.3 g of hydroquinone and add them to 80 mL of aqueous phase B, and stir at 300 r/min for 3 min; then weigh 20 g of microemulsion and add it to aqueous phase B, and stir at 1500 r/min for 5 min;

(5) Pour the jelly system into a vial, seal it, and place it at 90°C to gel.

The strength and blocking effect of the gel prepared in each embodiment are shown in Table 1.

Table 1 Gelation time, strength and plugging rate of each example

It can be seen that the four systems can gel within a certain period of time, and the gel strength is high, which meets the application requirements of oil fields and can achieve profile control and water plugging. The plugging rates of the four systems at different temperatures are all around 70%, which is different from the more than 95% plugging of the traditional gel system. After the interconnected multi-pores are generated, the plugging rate drops significantly, but plugging can still be achieved.

Claims (5)

1. An in-situ porous polymer gel system, characterized in that the gel system consists of a polymer main agent, a cross-linking agent, an in-situ gas generating additive A and an in-situ gas generating additive B, an auxiliary agent, an emulsifier, and a low molecular weight hydrocarbon; wherein the polymer main agent is an acrylamide/AMPS copolymer with a number average molecular weight of more than 800w; the cross-linking agent is urotropine, hydroquinone, and N,N-methylenebisacrylamide; the in-situ gas generating additive A is nitrous acid; the in-situ gas generating additive B is urea; the auxiliary agent is n-butanol or hexylene glycol; and the emulsifier is a combination of Span-80, OP-10, and SDS; The low molecular weight hydrocarbons are a combination of n-dodecane and diesel; The method for preparing an in-situ porous polymer jelly system is characterized in that the preparation steps are: (1) adding the in-situ gas generating additive A into water and stirring evenly to obtain a water phase A; (2) mixing the aqueous phase A and the low molecular weight hydrocarbons in the required proportion, adding the auxiliary agent and the emulsifier, and stirring evenly to prepare the oil external phase microemulsion; (3) adding the in-situ gas generating additive B, the polymer main agent and the cross-linking agent into water and stirring to obtain an aqueous phase B; (4) adding the oil external phase microemulsion to the water phase B under high-speed stirring to prepare a multiple emulsion; (5) heating the multiple emulsions into gels to obtain an in-situ porous polymer gel system; Wherein, the amount of the in-situ gas generating additive A in step (1) is 10% to 30%; the oil-water ratio in step (2) is 2:1 to 8:1, the ratio of the emulsifier to the auxiliary agent is 2:1 to 4:1, and the total concentration of the emulsifier and the auxiliary agent is 20% to 50%; the amount of the in-situ gas generating additive B in step (3) is 7% to 45%, the amount of the polymer main agent is 1% to 8.5%, and the amount of the cross-linking agent is 0.3% to 1%. 2. The method for preparing a jelly system according to claim 1, characterized in that the stirring rate is 200 r/min to 500 r/min. 3. The method for preparing a jelly system according to claim 1, characterized in that the stirring speed is 200 r/min to 400 r/min. 4. The method for preparing a jelly system according to claim 1, characterized in that the high-speed stirring speed in step (4) is 1000 r/min to 3000 r/min. 5. The method for preparing a jelly system according to claim 1, characterized in that the heating temperature in step (5) is 85°C to 95°C.