Nitrogen foam sand washing drilling plug liquid system and preparation method thereof

Abstract

The invention belongs to the technical field of oil exploitation, and particularly relates to a nitrogen foam sand washing drilling plug liquid system and a preparation method thereof. The preparation method comprises the following steps: adding 3-amino-1, 5-naphthalene disulfonic acid disodium salt, ethanol and alkyl halide into a reactor, uniformly stirring, heating, carrying out a heat preservation reaction, and regulating and maintaining the pH value to be 8-9 by using sodium hydroxide; adding chlorinated acid into the reactor, uniformly stirring, heating and refluxing, and regulating and maintaining the pH value to be 8-9 by using sodium hydroxide; decompressing and distilling to obtain viscous liquid, adding deionized water, heating and dissolving, filtering while hot, cooling to below 5 DEG C, separating out solid, filtering and drying to obtain the foaming agent; a foaming agent, a foam stabilizer and tap water are uniformly stirred in proportion, and the product nitrogen foam sand washing drilling plug liquid system is obtained. The nitrogen foam sand washing drilling plug liquid system has the advantages of large foaming volume and long half-life period.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum extraction, and in particular relates to a nitrogen foam sand flushing and drilling plug fluid system and a preparation method thereof. Background Art

[0002] During oil and gas production, sand production often occurs within the wellbore, particularly in horizontal wells, where it can significantly impact the connectivity between the wellbore and the formation. Currently, a common practice is to run a flushing pipe into the wellbore at the sand production location and use water circulation to flush the sand out of the formation. This method can address sand production in most oil and gas wells, but it is ineffective for wellbores with significant loss of flow (i.e., wellbores with excessive loss of flow that cannot be effectively flushed using conventional circulating sand flushing methods). This is because all the fluid flushed into the wellbore is lost to the formation, preventing return fluid from forming and, therefore, preventing the sand from being carried out of the wellhead.

[0003] One existing method for addressing sand flushing in high-loss wellbores is foam sand flushing. Foam sand flushing and drill plug flushing primarily utilize the unique properties of foam fluids. Foam consists of gas and liquid (typically a water-based liquid containing a surfactant). Its low density effectively reduces liquid column pressure and minimizes damage to the formation.

[0004] When foam fluid circulates in the wellbore, it has a strong carrying capacity. Due to the foam's elasticity and viscosity, it can carry solid particles such as sand or debris generated during the drilling process out of the wellbore during its upward flow, thereby achieving the purpose of clearing impurities in the wellbore.

[0005] CN1046150A discloses a cement foaming agent for oil and gas well cementing and its preparation method. The cement foaming agent is composed of metallic aluminum powder, a non-polar organic compound encapsulant, and an auxiliary agent. It can be stored for long periods within a temperature range of -20°C to 40°C and has good compatibility with other cement additives. Directly mixing the slurry with the foaming agent will essentially not react at temperatures below 40°C. However, upon entering the predetermined well section, the encapsulant gradually melts away, allowing the aluminum powder to react with the cement slurry to produce uniform bubbles, thereby compensating for the decrease in hydrostatic column pressure during the cement slurry solidification process and preventing annular airflow. The preparation method utilizes a melt-mixed, solvent-free encapsulation process, requiring simple equipment. However, the primary component of the gas produced by the foaming agent is hydrogen, resulting in poor cementing effectiveness and potential safety hazards, making it difficult to promote in actual production.

[0006] CN103194191A discloses a nanosilica-based foam drilling fluid, comprising at least the following components: 0.1-0.3% foaming agent, 0.1-0.3% foam stabilizer, 0.05-0.125% nanomaterial, and the balance water. The nanomaterial is nanosilica particles with a particle size of 10-20 nm. However, this foam drilling fluid has a small foaming volume and a short half-life, which limits its use in the field. Summary of the Invention

[0007] The present invention addresses the deficiencies of the prior art and provides a nitrogen foam sand flushing and drilling plugging fluid system and a preparation method thereof. The nitrogen foam sand flushing and drilling plugging fluid system of the present invention has the advantages of large foaming volume and long half-life.

[0008] One of the purposes of the present invention is to disclose a nitrogen foam sand drilling plugging fluid system, the composition and components of the nitrogen foam sand drilling plugging fluid system are as follows: 0.1-0.3 parts by mass of foaming agent; Foam stabilizer 0.05-0.2 parts by mass; 100 parts by mass of tap water.

[0009] The foam stabilizer is one or more of gelatin, carboxymethyl cellulose and hydroxyethyl cellulose.

[0010] The molecular structural formula of the foaming agent is as follows: ; Among them, R is C8-C 14 wherein n is a positive integer from 1 to 5.

[0011] Another object of the present invention is to disclose a method for preparing the nitrogen foam sand flushing and drilling plugging fluid system. The specific steps of the preparation method are as follows: (1) Add 3-amino-1,5-naphthalene disulfonic acid disodium salt, ethanol, and alkyl halide to the reactor, stir evenly, heat and keep warm for reaction, and adjust and maintain the pH at 8-9 with sodium hydroxide; (2) Add chlorinated acid to the above reactor, stir evenly, heat to reflux, and adjust and maintain the pH at 8-9 with sodium hydroxide; (3) Vacuum distillation to obtain a viscous liquid, add deionized water, heat to dissolve, filter while hot, cool to below 5°C, precipitate a solid, filter and dry to obtain a foaming agent; (4) Mix the foaming agent, foam stabilizer and tap water in proportion to obtain the nitrogen foam sand flushing and drilling plug fluid system.

[0012] In the present invention, preferably, based on 1 mol of 3-amino-1,5-naphthalene disulfonic acid disodium salt, the amounts of the alkyl halide and the chlorinated acid are 0.8-1.2 mol parts and 0.8-1.2 mol parts, respectively.

[0013] More preferably, based on 1 mol of 3-amino-1,5-naphthalene disulfonic acid disodium salt, the amounts of the alkyl halide and the chlorinated acid are 0.9-1.1 mol parts and 0.9-1.1 mol parts, respectively.

[0014] In the present invention, preferably, the structural formula of the alkyl halide is as follows: RX, Among them, R is C8-C 14 n-alkanes, X is Br or Cl.

[0015] In the present invention, preferably, the structural formula of the chlorinated acid is as follows: Cl(CH2) n COOH, Wherein, n is a positive integer from 1 to 5.

[0016] In the present invention, preferably, the mass ratio of ethanol to 3-amino-1,5-naphthalene disulfonic acid disodium salt in step (1) is 30-50:1.

[0017] In the present invention, preferably, the temperature of the heating and heat preservation reaction in step (1) is 50-80°C and the time is 0.5-2h.

[0018] In the present invention, preferably, the heating reflux time in step (2) is 1-6 hours.

[0019] In the present invention, preferably, the mass ratio of deionized water to 3-amino-1,5-naphthalene disulfonic acid disodium salt in step (3) is 20-40:1.

[0020] In the present invention, preferably, the mass ratio of the foaming agent, foam stabilizer and tap water in step (4) is 0.1-0.3:0.05-0.2:100.

[0021] In the present invention, preferably, the foam stabilizer in step (4) is one of gelatin, carboxymethyl cellulose and hydroxyethyl cellulose.

[0022] The foaming agent synthesis reaction equation of the present invention is as follows: ; Wherein, X is Cl or Br, and R is C8-C 14 wherein n is a positive integer from 1 to 5.

[0023] The nitrogen foam sand drilling plugging liquid system of the present invention is composed of a foaming agent, a foam stabilizer and water. The foaming agent is a composite anionic surfactant, the lipophilic groups are aliphatic hydrocarbons and naphthalene, and the hydrophilic groups are carboxylates and sulfonates. Gas enters the solution to form bubbles, which are composed of a liquid film surrounding some gas. On the inside of the liquid film, the hydrophobic group of the surfactant extends to the air inside the bubble; on the outside of the liquid film, the hydrophobic group of the surfactant extends to the air outside the bubble, thereby forming a bubble membrane. The foam stabilizer has a large molecular weight and contains more hydroxyl groups, which can increase the viscosity of the liquid, thereby slowing down the rising speed of the bubble, prolonging the existence time of the bubble, and increasing the half-life.

[0024] Compared with the prior art, the present invention has the following advantages and beneficial effects: (1) The nitrogen foam sand drilling plugging fluid system of the present invention has the characteristic of large foaming volume, which can reach up to 910 ml at room temperature; (2) The nitrogen foam sand drilling plug fluid system of the present invention has a long half-life, which can reach up to 1650s at room temperature. DETAILED DESCRIPTION

[0025] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0026] Example 1

[0027] (1) Add 20 mmol of 3-amino-1,5-naphthalene disulfonic acid disodium salt, 208 g of ethanol, and 16 mmol of chlorooctane into the reactor, stir evenly, heat to 50 ° C, keep the temperature for 1 hour, and adjust and maintain the pH at 8-9 with sodium hydroxide; (2) Add 24 mmol of chloroacetic acid to the above reactor, stir evenly, heat under reflux for 2 hours, and adjust and maintain the pH at 8-9 with sodium hydroxide; (3) Vacuum distillation was performed to obtain a viscous liquid, 139 g of deionized water was added, the solution was heated to dissolve, the solution was filtered while hot, the temperature was lowered to below 5°C, a solid was precipitated, and the solid was filtered and dried to obtain a foaming agent.

[0028] (4) Mix 0.1g of foaming agent, 0.05g of gelatin, and 100g of tap water in proportion and mix them evenly to obtain the nitrogen foam sand flushing and drilling plug liquid system.

[0029] Example 2

[0030] (1) Add 20 mmol of 3-amino-1,5-naphthalene disulfonic acid disodium salt, 347 g of ethanol, and 24 mmol of chlorodecane into the reactor, stir evenly, heat to 60°C, keep the temperature for 1 hour, and adjust and maintain the pH at 8-9 with sodium hydroxide; (2) Add 16 mmol of chloropropionic acid to the above reactor, stir evenly, heat under reflux for 1 hour, and adjust and maintain the pH at 8-9 with sodium hydroxide; (3) Vacuum distillation was performed to obtain a viscous liquid, 159 g of deionized water was added, the solution was heated to dissolve, the solution was filtered while hot, the temperature was lowered to below 5°C, a solid was precipitated, and the solid was filtered and dried to obtain a foaming agent.

[0031] (4) Mix 0.3 g of foaming agent, 0.2 g of gelatin, and 100 g of tap water in proportion to obtain the nitrogen foam sand drilling plug liquid system.

[0032] Example 3

[0033] (1) Add 20 mmol of 3-amino-1,5-naphthalene disulfonic acid disodium salt, 258 g of ethanol, and 18 mmol of tetradecane chloride into the reactor, stir evenly, heat to 50°C, keep warm for 2 hours, and adjust and maintain the pH at 8-9 with sodium hydroxide; (2) Add 22 mmol of chlorohexanoic acid to the above reactor, stir evenly, heat under reflux for 2 h, and adjust and maintain the pH at 8-9 with sodium hydroxide; (3) Vacuum distillation was performed to obtain a viscous liquid, 278 g of deionized water was added, the solution was heated to dissolve, the solution was filtered while hot, the temperature was lowered to below 5°C, a solid was precipitated, and the solid was filtered and dried to obtain a foaming agent.

[0034] (4) Mix 0.2 g of foaming agent, 0.08 g of gelatin, and 100 g of tap water in proportion to obtain the nitrogen foam sand drilling plugging liquid system.

[0035] Example 4

[0036] (1) Add 20 mmol of 3-amino-1,5-naphthalene disulfonic acid disodium salt, 300 g of ethanol, and 22 mmol of chlorododecane into the reactor, stir evenly, heat to 60°C, keep the temperature for 1 hour, and adjust and maintain the pH at 8-9 with sodium hydroxide; (2) Add 18 mmol of chlorohexanoic acid to the above reactor, stir evenly, heat under reflux for 4 hours, and adjust and maintain the pH at 8-9 with sodium hydroxide; (3) Vacuum distillation was performed to obtain a viscous liquid, 248 g of deionized water was added, the solution was heated to dissolve, the solution was filtered while hot, the temperature was lowered to below 5°C, a solid was precipitated, and the solid was filtered and dried to obtain a foaming agent.

[0037] (4) 0.11 g of foaming agent, 0.085 g of carboxymethyl cellulose, and 100 g of tap water were mixed evenly in proportion to obtain the nitrogen foam sand drilling plugging liquid system.

[0038] Example 5

[0039] (1) Add 20 mmol of 3-amino-1,5-naphthalene disulfonic acid disodium salt, 278 g of ethanol, and 19 mmol of chlorododecane into the reactor, stir evenly, heat to 70°C, keep the temperature for 1 hour, and adjust and maintain the pH at 8-9 with sodium hydroxide; (2) Add 21 mmol of chlorovaleric acid to the above reactor, stir evenly, heat under reflux for 2 h, and adjust and maintain the pH at 8-9 with sodium hydroxide; (3) Vacuum distillation was performed to obtain a viscous liquid, 199 g of deionized water was added, the solution was heated to dissolve, the solution was filtered while hot, the temperature was lowered to below 5°C, a solid was precipitated, and the solid was filtered and dried to obtain a foaming agent.

[0040] (4) 0.13 g of foaming agent, 0.05 g of carboxymethyl cellulose, and 100 g of tap water were mixed evenly in proportion to obtain the nitrogen foam sand drilling plugging liquid system.

[0041] Example 6

[0042] (1) Add 20 mmol of 3-amino-1,5-naphthalene disulfonic acid disodium salt, 310 g of ethanol, and 20 mmol of bromododecane into the reactor, stir evenly, heat to 80°C, keep the temperature for 0.5 h, and adjust and maintain the pH at 8-9 with sodium hydroxide; (2) Add 21 mmol of chlorobutyric acid to the above reactor, stir evenly, heat under reflux for 2 hours, and adjust and maintain the pH at 8-9 with sodium hydroxide; (3) Vacuum distillation to obtain a viscous liquid, add 240 g of deionized water, heat to dissolve, filter while hot, cool to below 5°C, precipitate a solid, filter and dry to obtain a foaming agent.

[0043] (4) 0.25 g of foaming agent, 0.1 g of hydroxyethyl cellulose, and 100 g of tap water were mixed evenly in proportion to obtain the nitrogen foam sand drilling plugging liquid system.

[0044] Example 7

[0045] (1) Add 20 mmol of 3-amino-1,5-naphthalene disulfonic acid disodium salt, 298 g of ethanol, and 21 mmol of bromododecane into the reactor, stir evenly, heat to 80°C, keep the temperature for 1 hour, and adjust and maintain the pH at 8-9 with sodium hydroxide; (2) Add 20 mmol of chlorobutyric acid to the above reactor, stir evenly, heat under reflux for 2 h, and adjust and maintain the pH at 8-9 with sodium hydroxide; (3) Vacuum distillation to obtain a viscous liquid, add 260 g of deionized water, heat to dissolve, filter while hot, cool to below 5°C, precipitate solid, filter and dry to obtain a foaming agent.

[0046] (4) 0.15 g of foaming agent, 0.10 g of carboxymethyl cellulose, 0.05 g of hydroxyethyl cellulose, and 100 g of tap water were mixed evenly in proportion to obtain the nitrogen foam sand drilling plugging liquid system.

[0047] Example 8 Foaming agent performance test Take 100 mL of the nitrogen foam sand drilling plug flushing liquid system (Examples 1-7) of the present invention, pour it into a high-stirring cup, place it on a high-speed stirrer, and introduce nitrogen gas into the upper end to maintain a nitrogen atmosphere. Start the high-speed stirrer and record the time with a stopwatch. Stir at a speed of (11000±300) r / min for 60 seconds. Quickly remove the high-stirring cup and pour all the generated foam liquid into a 1000 mL graduated cylinder. Record the time with a stopwatch. Then observe and record the foam volume in the graduated cylinder, which is the foaming volume.

[0048] The time it takes for 50 mL of liquid to separate out from the foam is recorded as the half-life.

[0049] At the same time, Guangzhou Zhonghai Oilfield cementing high-efficiency foaming agent 01 oilfield foaming agent was used for comparative experiments.

[0050] Table 1 Foaming performance test results

[0051] From Table 1 we can see that: (1) The nitrogen foam sand drilling plugging fluid system of the present invention (Examples 1-7) has the characteristic of large foaming volume. The foaming volume at room temperature reaches 800 ml or more, and the highest reaches 910 ml (Example 7). The foaming volume of the comparative example is 440 ml, which is significantly lower than that of the present invention.

[0052] (2) The nitrogen foam sand drilling plugging fluid system of the present invention (Examples 1-7) has the characteristic of a long half-life. The half-life at room temperature reaches more than 1120 seconds, and the highest reaches 1650 seconds (Example 7). The half-life of the comparative example is 510 seconds, which is significantly lower than that of the present invention.

[0053] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0054] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0055] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A nitrogen foam sand flushing and drilling plugging fluid system, characterized in that: The composition and components of the nitrogen foam sand flushing drilling plug fluid system are as follows: Foaming agent 0.1-0.3 parts by mass; Foam stabilizer 0.05-0.2 parts by mass; 100 parts by mass of tap water; The foam stabilizer is one or more of gelatin, carboxymethyl cellulose and hydroxyethyl cellulose; The molecular structural formula of the foaming agent is as follows: ； Where R is C8-C 14 wherein n is a positive integer from 1 to 5.

2. The method for preparing a nitrogen foam sand flushing and drilling plugging fluid system according to claim 1, characterized in that: The specific steps of the preparation method are as follows: (1) Add 3-amino-1,5-naphthalene disulfonic acid disodium salt, ethanol and alkyl halide into the reactor, stir evenly, heat and keep warm for reaction, and adjust and maintain the pH at 8-9 with sodium hydroxide; (2) Add chlorinated acid to the above reactor, stir evenly, heat to reflux, and adjust and maintain the pH at 8-9 with sodium hydroxide; (3) distill under reduced pressure to obtain a viscous liquid, add deionized water, heat to dissolve, filter while hot, cool to below 5°C, precipitate a solid, filter and dry to obtain a foaming agent; (4) Mix the foaming agent, foam stabilizer and tap water in proportion to obtain a nitrogen foam sand flushing and drilling plugging liquid system; Based on 1 mole of 3-amino-1,5-naphthalene disulfonic acid disodium salt, the amounts of the alkyl halide and the chlorinated acid are 0.8-1.2 mole parts and 0.8-1.2 mole parts respectively.

3. The preparation method according to claim 2, characterized in that: Based on 1 mole of 3-amino-1,5-naphthalene disulfonic acid disodium salt, the amounts of the alkyl halide and the chlorinated acid are 0.9-1.1 mole parts and 0.9-1.1 mole parts respectively.

4. The preparation method according to claim 2, characterized in that: The structural formula of the alkyl halide is as follows: RX, in, R is C8-C 14 n-alkane, X is Br or Cl.

5. The preparation method according to claim 2, characterized in that: The structural formula of the chlorinated acid is as follows: Cl(CH2) n COOH, Wherein, n is a positive integer from 1 to 5.

6. The preparation method according to claim 2, characterized in that: The heating and heat preservation reaction in step (1) is carried out at a temperature of 50-80°C and a time of 0.5-2h.

7. The preparation method according to claim 2, characterized in that: The heating reflux time in step (2) is 1-6 hours.

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