阅读说明：本技术 一种用于低压气井压井中的可降解暂堵材料及制备方法 (Degradable temporary plugging material for low-pressure gas well killing and preparation method thereof ) 是由 蒋文学 金娜 李勇 郑维师 陈平 吴增智 汪小宇 谭欢 万向辉 王坤 黄永章 于 2019-12-04 设计创作，主要内容包括：本发明涉及气田低压气井重复改造增产和储层保护技术领域,具体涉及一种用于低压气井压井中的可降解暂堵材料及制备方法,通过以重量百分比计,其组分为：主剂：45-65％；辅剂：15-25％；交联剂：5-10％；促降解剂：5-10％；抗氧化剂4-6％；固化剂4-6％；引发剂：2-4％；采用本发明可实现低压气井低伤害封堵和压井作业,低压气井压井用可降解暂堵材料在低压气井裂缝内和人工井底通过组合桥架、自粘合形成具有高强度、高摩阻、强封堵、低渗透性特点的压井段塞,阻止井底气体产出,降低作业过程中井控风险,在低压气井完成相应的井筒处理后,可降解暂堵材料缓慢降解,恢复储层渗透性,提升气藏整体采收率。(The invention relates to the technical field of gas field low-pressure gas well repeated modification yield increase and reservoir protection, in particular to a degradable temporary plugging material for low-pressure gas well killing and a preparation method thereof, wherein the degradable temporary plugging material comprises the following components in percentage by weight: a main agent: 45 to 65 percent; auxiliary agents: 15 to 25 percent; a crosslinking agent: 5 to 10 percent; degradation promoting agent: 5 to 10 percent; 4-6% of antioxidant; 4-6% of a curing agent; initiator: 2 to 4 percent; the invention can realize low-damage plugging and killing operation of the low-pressure gas well, the degradable temporary plugging material for killing the low-pressure gas well forms a killing section plug with the characteristics of high strength, high friction resistance, strong plugging and low permeability in a crack of the low-pressure gas well and an artificial well bottom through a combined bridge frame and self-adhesion, the gas output at the well bottom is prevented, the well control risk in the operation process is reduced, after the low-pressure gas well finishes corresponding shaft treatment, the degradable temporary plugging material is slowly degraded, the permeability of a reservoir is recovered, and the integral recovery ratio of the gas reservoir is improved.)

1. A degradable temporary plugging material for a low-pressure gas well kill, which is characterized in that: the composite material comprises the following components in percentage by weight: a main agent: 45 to 65 percent;

auxiliary agents: 15 to 25 percent;

a crosslinking agent: 5 to 10 percent;

degradation promoting agent: 5 to 10 percent;

4-6% of antioxidant;

4-6% of a curing agent;

initiator: 2 to 4 percent.

2. The degradable temporary plugging material for low pressure gas well kill wells of claim 1, wherein: the main agent comprises the following components in percentage by weight:

poly (ethyl methacrylate): 40-50%;

acrylonitrile-methyl acrylate copolymer: 10 to 15 percent;

polyethylene glycol diacrylate: 40-45 percent.

3. The degradable temporary plugging material for low pressure gas well kill as claimed in claim 2 wherein: the molecular weight of the polyethylene glycol diacrylate is 6000-8000.

4. The degradable temporary plugging material for low pressure gas well kill wells of claim 1, wherein: the auxiliary agent is 2-hydroxy-1, 4-naphthoquinone.

5. The degradable temporary plugging material for low pressure gas well kill wells of claim 1, wherein: the cross-linking agent is one or a mixture of methoxyethyl acrylate or 2-propylheptyl acrylate.

6. The degradable temporary plugging material for low pressure gas well kill wells of claim 1, wherein: the degradation promoter is one or a mixture of diisobutyl ketone or 4-methyl-2-pentanone.

7. The degradable temporary plugging material for low pressure gas well kill wells of claim 1, wherein: the antioxidant is one or a mixture of dibutyltin maleate and lead salicylate.

8. The degradable temporary plugging material for low pressure gas well kill wells of claim 1, wherein: the curing agent is one or a mixture of cobalt naphthenate and cobalt octoate.

9. The degradable temporary plugging material for low pressure gas well kill wells of claim 1, wherein: the initiator is one or a mixture of dimethylaniline and methylaniline.

10. A method for preparing a degradable temporary plugging material for a low-pressure gas well kill, which comprises the steps of any one of claims 1 to 9, wherein the method is characterized in that: the method comprises the following steps:

the method comprises the following steps: preparing a main agent, an auxiliary agent, a cross-linking agent, a degradation promoter, an antioxidant, a curing agent and an initiator according to the formula amount of each component;

step two: on the basis of the first step, the mixture is synthesized by a high-temperature stirring kettle and a double-screw extruder under the condition of vacuumizing protection, the auxiliary agent and the degradation promoter are added into the high-temperature stirring kettle according to the formula amount, the temperature control speed is 3-5 ℃/min, and the mixture is reacted for 20-30min when the temperature is raised to 140 ℃;

step three: on the basis of the second step, adding a main agent with the formula amount, adding an antioxidant with the formula amount, controlling the temperature at 1-2 ℃/min, and reacting for 10-20min when the temperature is raised to 160 ℃;

step four: on the basis of the third step, starting a vacuumizing device of the double-screw extruder, heating to 180 ℃, wherein the temperature deviation of the double-screw extruder is not more than +/-2 ℃;

step five: on the basis of the fourth step, quickly pushing reactants in the high-temperature stirring kettle to a feed inlet of a double-screw extruder, simultaneously adding a cross-linking agent, a curing agent and an initiator according to the formula amount, reacting for 5-10min, and controlling the rotating speed of a tractor to be 10-30 m/min;

step six: and on the basis of the fifth step, obtaining degradable temporary plugging material particles with the length of 0.5-5mm for killing the well of the low-pressure gas well by controlling the rotating speed of the granulator.

Technical Field

The invention relates to the technical field of gas field low-pressure gas well repeated modification yield increase and reservoir protection, in particular to a degradable temporary plugging material for low-pressure gas well killing and a preparation method thereof.

Background

The method comprises the steps that during the production process of a gas well, with the production of natural gas, the formation pressure is gradually reduced, and the formation pressure of the gas well is lower than the clear water liquid column pressure of a shaft, so that a low-pressure gas well is formed, well killing of the low-pressure gas well mainly comprises the following two sources of ①, the low-pressure gas well has certain gas yield but cannot meet the requirement for efficient production, well killing operation is firstly carried out on the low-pressure gas well, then secondary measure reservoir transformation is carried out, ②, although the gas yield of the low-pressure gas well meets the requirement for production, the pipe column or the wellhead in the shaft has large risk potential for a long time, and then other well repairing operation.

The well killing materials are various, such as quartz powder, barite powder, superfine calcium carbonate, rubber particles and the like, but the materials ① cannot be degraded after well killing and bring permanent damage to the reservoir, the gas well still has a gas invasion phenomenon after ② well killing, and the well killing materials ① such as gel particles, bulk expanded particles, frozen colloid and water-absorbent resin have low well killing strength, have high possibility of gas breakthrough, and simultaneously have large fluid loss during well killing, ② polymer materials cannot be degraded in the stratum and the shaft, so that secondary measures cannot be carried out.

Chinese patent No. CN106479464A, 3, 8.2017, discloses a temporary plugging type high-temperature well control fluid suitable for low-permeability oil reservoirs and a preparation method thereof, and the temporary plugging type high-temperature well control fluid consists of an inorganic salt solution and an additive, wherein the inorganic salt solution is prepared from fresh water: calcium chloride: the calcium bromide is prepared from 300: 130-252: 0-120 parts by mass; the additive is composed of the following raw materials in parts by mass of an inorganic salt solution: 1.4-1.6% of high-temperature-resistant corrosion inhibitor, 0.9-1.1% of stabilizer, 0.1-0.15% of surfactant, 1-1.5% of ultralow permeability agent, 1.9-2.1% of high-temperature-resistant modified starch filtrate reducer, 3-5% of temporary plugging material, 0.1-0.3% of temperature-resistant tackifying shear promoter or 3-6% of oligomeric thickener, 1-1.5% of liquid oil solution temporary plugging agent or 1-2% of low-fluorescence sulfonated asphalt. Chinese patent No. CN103775023A, 5.7.2014 discloses a low-pressure oil and gas well killing method, firstly, preparing alkaline guanidine glue solution and oil-soluble temporary plugging agent with proper concentration according to well conditions (shaft volume, gas production rate and the like); mixing the oil-soluble temporary plugging agent and the guanidine gum solution, and then fully and uniformly stirring to suspend the temporary plugging agent in the guanidine gum solution; sending the mixture formed by the oil-soluble temporary plugging agent and the guanidine gum solution into the stratum by adopting a matched process and ground pipelines and equipment; the method can be realized by adopting a matched tubular column process: the guanidine gum solution carries the temporary plugging agent to plug and shield the stratum, thereby avoiding the loss of the well killing fluid injected into the shaft, meanwhile, the alkaline guanidine gum solution filled in the shaft has better air tightness and better safety to acid gas (hydrogen sulfide, carbon dioxide and the like), preventing the stratum gas from entering the shaft, ensuring the success of well killing and being beneficial to the subsequent well repairing operation. The invention has the beneficial effects that: the near-wellbore area near the blast hole is effectively blocked, the loss of the well killing fluid is prevented from entering the stratum, and the stratum gas is prevented from entering the shaft, so that the well repairing operation is ensured to be carried out smoothly.

The temporary plugging material for killing the well represented by the patent has the following problems that ① frozen colloid is added with oil soluble particles, because the plugging performance of the frozen colloid in a shaft and a stratum is relatively poor, a long section of the frozen colloid is required to be plugged in the gas well, the long section of the frozen colloid is difficult in the gel breaking process, meanwhile, the oil soluble particles can only be softened in the gas well and can not be dissolved, if the melting point of the oil soluble particles is low, the plugging effect cannot be achieved, if the melting point of the oil soluble particles is high, cracks and a well bottom always exist, the later yield is influenced, ② aggravated solution density can accelerate and lead to the filtration loss of a large amount of killing fluid into the reservoir of the low-pressure gas well, when the plugging pressure balance is achieved by using a polymer starch type filtrate reducer and a polymer on the wall of the cracks, great damage and decrement are brought to the later-stage reservoir protection and the productivity of the low-stage gas well, meanwhile, the characteristics that the degradation rate of high-concentration inorganic salt and stratum water generation gas well and polymer in the gas well, and the degradation rate is low, the secondary damage is brought to the later-stage reservoir plugging pressure well, and the scaling reduction of the plugging operation can be achieved.

Disclosure of Invention

The invention overcomes the defects of the prior art, and provides a degradable temporary plugging material for killing a well in a low-pressure gas well and a preparation method thereof, in particular to a well killing slug material which is formed by self-bonding the degradable temporary plugging material in a crack of the low-pressure gas well and an artificial well bottom through a combined bridge frame and has the characteristics of high strength, high friction resistance, strong plugging and low permeability, so that the output of gas at the well bottom is prevented, the well control risk in the operation process is reduced, after the low-pressure gas well completes corresponding well shaft treatment, the degradable temporary plugging material is slowly degraded, the permeability of a reservoir is recovered, the integral recovery ratio of a gas reservoir is improved, and the low-damage plugging and well killing operation of the low-pressure.

The technical problem solved by the invention can be realized by adopting the following technical scheme:

a degradable temporary plugging material for a low-pressure gas well kill well comprises the following components in percentage by weight:

a main agent: 45 to 65 percent;

auxiliary agents: 15 to 25 percent;

a crosslinking agent: 5 to 10 percent;

degradation promoting agent: 5 to 10 percent;

4-6% of antioxidant;

4-6% of a curing agent;

initiator: 2 to 4 percent.

The main agent comprises the following components in percentage by weight:

poly (ethyl methacrylate): 40-50%;

acrylonitrile-methyl acrylate copolymer: 10 to 15 percent;

polyethylene glycol diacrylate: 40-45 percent.

The molecular weight of the polyethylene glycol diacrylate is 6000-8000.

The auxiliary agent is 2-hydroxy-1, 4-naphthoquinone.

The cross-linking agent is one or a mixture of methoxyethyl acrylate or 2-propylheptyl acrylate.

The degradation promoter is one or a mixture of diisobutyl ketone or 4-methyl-2-pentanone.

The antioxidant is one or a mixture of dibutyltin maleate and lead salicylate.

The curing agent is one or a mixture of cobalt naphthenate and cobalt octoate.

The initiator is one or a mixture of dimethylaniline and methylaniline.

The preparation method of the degradable temporary plugging material for the low-pressure gas well kill, which comprises any one of the above steps, comprises the following steps:

the method comprises the following steps: preparing a main agent, an auxiliary agent, a cross-linking agent, a degradation promoter, an antioxidant, a curing agent and an initiator according to the formula amount of each component;

step two: on the basis of the first step, the mixture is synthesized by a high-temperature stirring kettle and a double-screw extruder under the condition of vacuumizing protection, the auxiliary agent and the degradation promoter are added into the high-temperature stirring kettle according to the formula amount, the temperature control speed is 3-5 ℃/min, and the mixture is reacted for 20-30min when the temperature is raised to 140 ℃;

step three: on the basis of the second step, adding a main agent with the formula amount, adding an antioxidant with the formula amount, controlling the temperature at 1-2 ℃/min, and reacting for 10-20min when the temperature is raised to 160 ℃;

step four: on the basis of the third step, starting a vacuumizing device of the double-screw extruder, heating to 180 ℃, wherein the temperature deviation of the double-screw extruder is not more than +/-2 ℃;

step five: on the basis of the fourth step, quickly pushing reactants in the high-temperature stirring kettle to a feed inlet of a double-screw extruder, and simultaneously adding a cross-linking agent in a formula amount; a curing agent in a formulated amount; reacting the initiator with the formula amount for 5-10min, and controlling the rotating speed of a tractor to be 10-30 m/min;

step six: and on the basis of the fifth step, obtaining degradable temporary plugging material particles with the length of 0.5-5mm for killing the well of the low-pressure gas well by controlling the rotating speed of the granulator.

The invention has the beneficial effects that:

compared with the prior art, the invention comprises the following steps:

1. the plugging agent has the advantages of lower dosage, greatly enhanced plugging capability and large reduction range of permeability of the kill slug due to the self-bonding function.

The poly (ethyl methacrylate), the acrylonitrile/methyl acrylate copolymer and the polyethylene glycol diacrylate (molecular weight 6000-8000) in the body have higher softening point and hardness, and have excellent comprehensive mechanical properties due to the existence of asymmetric carbon atoms of a polymer molecular framework, particularly high strength and high combined bridging plugging performance. Thus, the use amount is obviously reduced under the same stress. Antioxidant: one or the mixture of dibutyltin maleate and lead salicylate can maintain the basic performance of the bulk material at high temperature, is beneficial to material processing, and prevents the material from aging and denaturation at overhigh temperature. The curing agent of the invention: one or a mixture of cobalt naphthenate or cobalt octoate reacts at high temperature, so that the lower surface of the reservoir can be solidified at about 100 ℃, the polyethyl methacrylate, the acrylonitrile/methyl acrylate copolymer and the polyethylene glycol diacrylate material in the body are bonded with each other to form a plugging slug with lower permeability, the plugging slug is in contact with rock to increase the friction force of a slug system, the bearing strength of the slug is further improved, and well killing plugging is facilitated.

2. Can be uniformly degraded in formation water, acid and alkali media, and has wider application range.

In the main agent of the invention, the polyethyl methacrylate, the acrylonitrile/methyl acrylate copolymer and the polyethylene glycol diacrylate and the auxiliary agent are as follows: the 2-hydroxy-1, 4-naphthoquinone is not affected by acid and alkali media, so that the naphthoquinone derivative can be used for carrying media with different pH values when used on the ground, can be used for plugging in different working liquid systems, and has an expanded application range for killing low-pressure gas wells. The main body and the auxiliary agent are mixed in a cross-linking agent: forming a composite macromolecular compound under the action of one or a mixture of methoxyethyl acrylate or 2-propylheptyl acrylate, and then treating the macromolecular compound by a degradation promoter: one of diisobutyl ketone or 4-methyl-2-pentanone or a mixture thereof and an initiator: one or a mixture of dimethylaniline and methylaniline reacts under the synergistic effect to have the characteristic of self-degradation, and the self-degradation is only controlled by the temperature and the mineralization degree in formation water. In the main agent, the poly (ethyl methacrylate), the acrylonitrile-methyl acrylate copolymer and the polyethylene glycol diacrylate decompose alpha-olefin, 2-hydroxy-1, 4-naphthoquinone is volatilized and decomposed at temperature, and can be degraded rapidly under the condition of high mineralization degree in formation water, and in the process of plugging and killing a well, the degradable temporary plugging material cannot contact with a high mineralization medium in low mineralization degree, so that the plugging performance cannot be influenced; when the killing operation is completed and the degradable temporary plugging material is slowly degraded by the influence of temperature, formation water and gas flow to the position close to the well casing and contact with the degradable temporary plugging material, so that the material degradation is accelerated, and the damage of material residues to a reservoir is reduced.

Drawings

The invention is further illustrated with reference to the following figures and examples.

FIG. 1 is a schematic diagram of a fracture core plugging pressure-bearing test by using the degradable temporary plugging material.

Fig. 2 is a schematic diagram of a degradation rate test of the degradable temporary plugging material in different media.

Detailed Description