Nitrogen foam sand washing drilling plug liquid system as well as preparation method and application 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 and application thereof. The preparation method comprises the following steps: adding p-nonylphenol, lauryl amine, 40wt% formaldehyde and medical alcohol into a reactor, stirring, heating and refluxing; adding chloroacetic acid, adjusting the pH value to 8-9 by using a sodium hydroxide solution, and heating and refluxing; carrying out reduced pressure distillation until the content of ethanol in distillation residues is lower than 5wt%, cooling to 40 DEG C or below, adjusting the pH to 2-3 by hydrochloric acid, cooling to 10 DEG C or below, separating out solids, filtering and drying to obtain the foaming agent; the foaming agent, the foam stabilizer and tap water are uniformly stirred in proportion, the pH is adjusted to be 8-9 with potassium hydroxide, 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 present invention belongs to the technical field of oil exploitation, and particularly relates to a nitrogen foam sand washing and plug drilling fluid system, a preparation method thereof and an application thereof. Background Art

[0002] During the process of oil exploitation, sand production in oil wells is a relatively common and complex phenomenon. With the continuous deepening of oilfield development, the reservoir pressure gradually decreases, and the rock cementation strength decreases. Under the action of suction, pressure difference and other factors in the exploitation operation, formation sand will enter the wellbore with the fluid and continuously deposit in the wellbore, eventually leading to the occurrence of sand plugging problems. Sand plugging will seriously affect the normal production of oil wells, reduce the oil well output, and even cause the oil well to shut down.

[0003] At the same time, in the workover operation of oil wells, plug drilling operation is also very common. Plug drilling refers to drilling out the plugs formed for various reasons in the oil well, such as cement plugs, bridge plugs, etc. A large amount of debris and cuttings will be generated during the plug drilling process. If these substances cannot be effectively removed from the wellbore in time, they will accumulate in the wellbore, form a new blockage, hinder the progress of subsequent operations, and affect the normal production recovery of oil wells.

[0004] Nitrogen foam fluid has unique rheological properties. It contains a large number of bubbles inside, and these bubbles play a role similar to "ball bearings" in the fluid, which can significantly reduce the viscosity and frictional resistance of the fluid, making the fluid flow more smoothly in the wellbore. At the same time, nitrogen foam fluid has high viscosity and elasticity, and can effectively suspend and carry sand grains. Even in horizontal wells or highly deviated wells, it can stably carry sand grains to the ground, greatly improving the efficiency of sand washing and plug drilling.

[0005] Among them, the performance of the foaming agent directly affects the effect of sand washing and plug drilling. Developing a foaming agent with good foaming performance, strong foam stability, good compatibility and low cost is the key to solving the problems of the existing nitrogen foam sand washing and plug drilling fluid system, and has important practical significance for improving the performance and application effect of nitrogen foam sand washing and plug drilling fluid.

[0006] CN104109520A discloses a foaming agent suitable for high-temperature and high-salt reservoirs and a preparation method thereof. The foaming agent includes: 50-70wt% of alkyl sulfonate, 10-15wt% of alkyl amine oxide, and the rest is distilled water. The pH value of the foaming agent is 7-9. The method includes: adding alkyl sulfonate, alkyl amine oxide and distilled water into the reaction kettle in turn while stirring, and obtaining the foaming agent after mixing evenly; the temperature of the reaction kettle is 30-70°C. The foaming agent of this invention has strong foaming ability, high tolerance to salinity, high tolerance to calcium and magnesium ions and good compatibility with formation water. However, the foam stability of this invention is poor, and the low interfacial tension performance is not considered.

[0007] CN101798499B discloses a strong inhibition and anti-collapse foam fluid for drilling, which is composed of the following components and their parts by weight: 0.09 - 0.11 parts of foam stabilizer, 0.36 - 0.44 parts of foaming agent, 2.34 - 2.86 parts of anti-collapse agent, 2.7 - 3.3 parts of filtrate reducer, and 94.51 - 93.29 parts of water. When gas drilling encounters complex formation water inflow situations, using the foam fluid of this invention can effectively improve the ability to carry rock and water, and at the same time protect the stability of the upper wellbore. Laboratory research proves that this foam fluid has strong foaming ability, the foaming volume ≥ 500%, and a moderate half-life, which is easy to control and is beneficial to the construction of drilling engineering. However, this foam fluid system has general temperature resistance performance, and the large amount of ultra-high molecular weight polymer used leads to slow preparation and dissolution of the foam fluid, affecting the on-site construction efficiency. Summary of the Invention

[0008] The present invention provides a nitrogen foam sand washing and plug drilling fluid system and its preparation method in view of the deficiencies of the above-mentioned prior art. The nitrogen foam sand washing and plug drilling fluid system of the present invention has the advantages of large foaming volume and long half-life.

[0009] One object of the present invention discloses a nitrogen foam sand washing and plug drilling fluid system, and the composition and components of the nitrogen foam sand washing and plug drilling fluid system are as follows: The formula is as follows: 0.2 - 0.5 parts by mass of foaming agent; 0.1 - 0.3 parts by mass of foam stabilizer; 100 parts by mass of tap water.

[0010] Among them, the foam stabilizer is one of gelatin, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and polyvinyl alcohol.

[0011] The molecular structural formula of the foaming agent is as follows: .

[0012] Another object of the present invention discloses a preparation method of the above-mentioned nitrogen foam sand washing and plug drilling fluid system, and the specific steps of the preparation method are as follows: (1) Add p-nonylphenol, dodecylamine, 40wt% formaldehyde, and medical alcohol into a reactor, stir and heat to reflux; (2) Add chloroacetic acid, adjust the pH to 8 - 9 with sodium hydroxide solution, and heat to reflux; (3) Distill under reduced pressure until the ethanol content in the distillation residue is lower than 5wt%, cool to below 40°C, adjust the pH to 2 - 3 with hydrochloric acid, cool to below 10°C, precipitate solids, filter, and dry to obtain the foaming agent; (4) Stir the foaming agent, foam stabilizer, and tap water evenly in proportion, and adjust the pH to 8 - 9 with potassium hydroxide to obtain the product nitrogen foam sand washing and plug drilling fluid system.

[0013] In the present invention, preferably, based on 1 mole part of p-nonylphenol, the amounts of dodecylamine, 40 wt% formaldehyde, and chloroacetic acid are 1.6 - 2.4 mole parts, 2.0 - 3.0 mole parts, and 1.6 - 2.4 mole parts respectively; more preferably, based on 1 mole part of p-nonylphenol, the amounts of dodecylamine, 40 wt% formaldehyde, and chloroacetic acid are 1.8 - 2.2 mole parts, 2.2 - 2.8 mole parts, and 1.8 - 2.2 mole parts respectively.

[0014] In the present invention, preferably, in step (1), the weight ratio of the medical alcohol to p-nonylphenol is 8 - 12:1.

[0015] In the present invention, preferably, in step (1), the heating reflux time is 6 - 24 h.

[0016] In the present invention, preferably, in step (2), the heating reflux time is 1 - 4 h.

[0017] The synthesis reaction equation of the foaming agent of the present invention is as follows:

[0018] The third object of the present invention discloses the application of the above nitrogen foam sand washing and plug drilling fluid system in oil well sand washing and plug drilling operations.

[0019] The nitrogen foam sand washing and plug drilling fluid system of the present invention is composed of a foaming agent, a foam stabilizer, and water. The foaming agent is a gemini anionic surfactant, the lipophilic group is dodecane and nonyl, and the hydrophilic group is carboxylate, which can greatly reduce the interfacial tension between the gas-liquid two phases and reduce the energy required for the liquid film to bend. The foam stabilizer molecule contains more hydroxyl groups and has a larger molecular weight, which can increase the viscosity of the liquid, thereby prolonging the existence time of the bubbles and increasing the half-life.

[0020] The present invention has the following advantages and beneficial effects compared with the prior art: (1) The nitrogen foam sand washing and plug drilling fluid system of the present invention has the characteristic of a large foaming volume, reaching up to 910 ml at room temperature; (2) The nitrogen foam sand washing and plug drilling fluid system of the present invention has the characteristic of a long half-life, reaching up to 2135 s at room temperature. Specific embodiments

[0021] The endpoints and any values in the ranges disclosed herein are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0022] The technical solution of the present invention will be further described below in conjunction with specific embodiments: Example 1

[0023] (1) Add 0.1 mol of nonylphenol, 0.16 mol of dodecylamine, 0.2 mol of 40 wt% formaldehyde, and 176 g of medical alcohol into the reactor, stir and heat up to reflux for 12 h; (2) Add 0.16 mol of chloroacetic acid, adjust the pH to 8 - 9 with sodium hydroxide solution, and heat to reflux for 1 h.

[0024] (3) Distill under reduced pressure until the ethanol content in the residue is less than 5 wt%, cool to below 40 °C, adjust the pH to 2 - 3 with hydrochloric acid, cool to below 10 °C, precipitate solids, filter and dry to obtain the foaming agent.

[0025] (4) Stir 0.2 g of the foaming agent, 0.1 g of gelatin, and 100 g of tap water evenly in proportion, adjust the pH to 8 - 9 with potassium hydroxide to obtain the product nitrogen foam sand washing and plug drilling fluid system.

[0026] Example 2

[0027] (1) Add 0.1 mol of nonylphenol, 0.24 mol of dodecylamine, 0.2 mol of 40 wt% formaldehyde, and 180 g of medical alcohol into the reactor, stir and heat up to reflux for 8 h; (2) Add 0.18 mol of chloroacetic acid, adjust the pH to 8 - 9 with sodium hydroxide solution, and heat to reflux for 1 h.

[0028] (3) Distill under reduced pressure until the ethanol content in the residue is less than 5 wt%, cool to below 40 °C, adjust the pH to 2 - 3 with hydrochloric acid, cool to below 10 °C, precipitate solids, filter and dry to obtain the foaming agent.

[0029] (4) Stir 0.25 g of the foaming agent, 0.1 g of gelatin, and 100 g of tap water evenly in proportion, adjust the pH to 8 - 9 with potassium hydroxide to obtain the product nitrogen foam sand washing and plug drilling fluid system.

[0030] Example 3

[0031] (1) Add 0.1 mol of p-nonylphenol, 0.17 mol of dodecylamine, 0.3 mol of 40 wt% formaldehyde, and 264 g of medical alcohol into the reactor, stir and heat to reflux for 12 h; (2) Add 0.24 mol of chloroacetic acid, adjust the pH to 8 - 9 with sodium hydroxide solution, and heat to reflux for 2 h.

[0032] (3) Distill under reduced pressure until the ethanol content in the residue is less than 5 wt%, cool to below 40 °C, adjust the pH to 2 - 3 with hydrochloric acid, cool to below 10 °C, precipitate solids, filter and dry to obtain the foaming agent.

[0033] (4) Stir 0.3 g of the foaming agent, 0.15 g of carboxymethyl cellulose, and 100 g of tap water evenly in proportion, adjust the pH to 8 - 9 with potassium hydroxide to obtain the product nitrogen foam sand washing and plug drilling fluid system.

[0034] Example 4

[0035] (1) Add 0.1 mol of p-nonylphenol, 0.22 mol of dodecylamine, 0.22 mol of 40 wt% formaldehyde, and 186 g of medical alcohol into the reactor, stir and heat to reflux for 4 h; (2) Add 0.22 mol of chloroacetic acid, adjust the pH to 8 - 9 with sodium hydroxide solution, and heat to reflux for 2 h.

[0036] (3) Distill under reduced pressure until the ethanol content in the residue is less than 5 wt%, cool to below 40 °C, adjust the pH to 2 - 3 with hydrochloric acid, cool to below 10 °C, precipitate solids, filter and dry to obtain the foaming agent.

[0037] (4) Stir 0.35 g of the foaming agent, 0.15 g of hydroxyethyl cellulose, and 100 g of tap water evenly in proportion, adjust the pH to 8 - 9 with potassium hydroxide to obtain the product nitrogen foam sand washing and plug drilling fluid system.

[0038] Example 5

[0039] (1) Add 0.1 mol of p-nonylphenol, 0.18 mol of dodecylamine, 0.28 mol of 40 wt% formaldehyde, and 200 g of medical alcohol into the reactor, stir and heat to reflux for 12 h; (2) Add 0.19 mol of chloroacetic acid, adjust the pH to 8 - 9 with sodium hydroxide solution, and heat to reflux for 4 h.

[0040] (3) Distill under reduced pressure until the ethanol content in the residue is less than 5 wt%, cool to below 40 °C, adjust the pH to 2 - 3 with hydrochloric acid, cool to below 10 °C, precipitate solids, filter and dry to obtain the foaming agent.

[0041] (4) Stir 0.4 g of foaming agent, 0.2 g of hydroxyethyl cellulose, and 100 g of tap water evenly in proportion, and adjust the pH to 8 - 9 with potassium hydroxide to obtain the product nitrogen foam sand washing and plug drilling fluid system.

[0042] Example 6

[0043] (1) Add 0.1 mol of p-nonylphenol, 0.19 mol of dodecylamine, 0.26 mol of 40 wt% formaldehyde, and 210 g of medical alcohol into the reactor, stir and heat to reflux for 12 h; (2) Add 0.21 mol of chloroacetic acid, adjust the pH to 8 - 9 with sodium hydroxide solution, and heat to reflux for 4 h.

[0044] (3) Distill under reduced pressure until the ethanol content in the residue is less than 5 wt%, cool to below 40 °C, adjust the pH to 2 - 3 with hydrochloric acid, cool to below 10 °C, precipitate solids, filter, and dry to obtain the foaming agent.

[0045] (4) Stir 0.45 g of foaming agent, 0.25 g of hydroxypropyl cellulose, and 100 g of tap water evenly in proportion, and adjust the pH to 8 - 9 with potassium hydroxide to obtain the product nitrogen foam sand washing and plug drilling fluid system.

[0046] Example 7

[0047] (1) Add 0.1 mol of p-nonylphenol, 0.21 mol of dodecylamine, 0.24 mol of 40 wt% formaldehyde, and 204 g of medical alcohol into the reactor, stir and heat to reflux for 24 h; (2) Add 0.2 mol of chloroacetic acid, adjust the pH to 8 - 9 with sodium hydroxide solution, and heat to reflux for 3 h.

[0048] (3) Distill under reduced pressure until the ethanol content in the residue is less than 5 wt%, cool to below 40 °C, adjust the pH to 2 - 3 with hydrochloric acid, cool to below 10 °C, precipitate solids, filter, and dry to obtain the foaming agent.

[0049] (4) Stir 0.5 g of foaming agent, 0.25 g of polyvinyl alcohol, and 100 g of tap water evenly in proportion, and adjust the pH to 8 - 9 with potassium hydroxide to obtain the product nitrogen foam sand washing and plug drilling fluid system.

[0050] Example 8

[0051] (1) Add 0.1 mol of p-nonylphenol, 0.2 mol of dodecylamine, 0.25 mol of 40 wt% formaldehyde, and 208 g of medical alcohol into the reactor, stir and heat to reflux for 24 h; (2) Add 0.21 mol of chloroacetic acid, adjust the pH to 8 - 9 with sodium hydroxide solution, and heat to reflux for 3 h.

[0052] (3) Distill under reduced pressure until the ethanol content in the residue is less than 5 wt%, cool to below 40 °C, adjust the pH to 2 - 3 with hydrochloric acid, cool to below 10 °C, precipitate solids, filter and dry to obtain the foaming agent.

[0053] (4) Stir 0.5 g of the foaming agent, 0.3 g of polyvinyl alcohol, and 100 g of tap water evenly in proportion, and adjust the pH to 8 - 9 with potassium hydroxide to obtain the product nitrogen foam sand washing and plug drilling fluid system.

[0054] Example 9 Performance Test of the Foaming Agent Take 100 mL of the nitrogen foam sand washing and plug drilling fluid system (Examples 1 - 8) of the present invention, pour it into a high - speed stirring cup, place it on a high - speed stirrer, introduce nitrogen gas at the upper end to maintain a nitrogen atmosphere, start the high - speed stirrer, and at the same time record the time with a stopwatch. Stir at a speed of (11000 ± 300) r / min for 60 s, quickly remove the high - speed stirring cup, pour all the generated foam liquid into a 1000 mL graduated cylinder, and record the time with a stopwatch. Immediately observe and record the foam volume in the graduated cylinder, which is the foaming volume.

[0055] Record the time used when the liquid separates from the foam to 50 mL, which is the half - life.

[0056] At the same time, conduct a comparative experiment with the drilling foaming agent of Jinan Honghaoyuan Chemical Technology Co., Ltd. with a concentration of 0.5 wt%. The test results are shown in Table 1.

[0057] Table 1 Test Results of Foaming Performance

[0058] It can be seen from Table 1 that: (1) The nitrogen foam sand washing and plug drilling fluid system (Examples 1 - 8) of the present invention has the characteristic of large foaming volume. At room temperature, the foaming volume reaches 820 ml or more, and the highest reaches 910 ml (Example 8), while the foaming volume of the comparative example is 480 ml, which is significantly lower than that of the present invention.

[0059] (2) The nitrogen foam sand washing and plug drilling fluid system (Examples 1 - 8) of the present invention has the characteristic of long half - life. At room temperature, the half - life reaches more than 1520 s, and the highest reaches 2135 s (Example 8), while the half - life of the comparative example is 980 s, which is significantly lower than that of the present invention.

[0060] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above - mentioned embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0061] In addition, it should be noted that, among the various specific technical features described in the above specific embodiments, they can be combined in any suitable manner without conflict. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods.

[0062] In addition, any combination can be made among various different embodiments of the present invention, as long as it does not violate the idea of the present invention, and it should also be regarded as the content disclosed by the present invention.

Claims

1. A nitrogen foam sand washing and plug drilling fluid system, characterized in that, The composition and components of the nitrogen foam sand washing and plug drilling fluid system are as follows: Foaming agent: 0.2 - 0.5 parts by mass; Foam stabilizer: 0.1 - 0.3 parts by mass; Tap water: 100 parts by mass; The foam stabilizer is one of gelatin, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and polyvinyl alcohol; The molecular structural formula of the foaming agent is as follows: 。 2. The preparation method of the nitrogen foam sand washing and plug drilling fluid system according to claim 1, characterized in that, The specific steps of the preparation method are as follows: (1) Add p-nonylphenol, dodecylamine, 40 wt% formaldehyde, and medical alcohol into a reactor, stir, heat up, and reflux; (2) Add chloroacetic acid, adjust the pH to 8 - 9 with sodium hydroxide solution, and heat under reflux; (3) Distill under reduced pressure until the ethanol content in the residue is less than 5 wt%, cool to below 40 °C, adjust the pH to 2 - 3 with hydrochloric acid, cool to below 10 °C, precipitate solids, filter, and dry to obtain the foaming agent; (4) Stir the foaming agent, foam stabilizer, and tap water evenly in proportion, and adjust the pH to 8 - 9 with potassium hydroxide to obtain the product nitrogen foam sand washing and plug drilling fluid system; Based on 1 mole of p-nonylphenol, the dosages of dodecylamine, 40 wt% formaldehyde, and chloroacetic acid are 1.6 - 2.4 moles, 2.0 - 3.0 moles, and 1.6 - 2.4 moles respectively.

3. The preparation method according to claim 2, wherein Based on 1 mole of p-nonylphenol, the dosages of dodecylamine, 40 wt% formaldehyde, and chloroacetic acid are 1.8 - 2.2 moles, 2.2 - 2.8 moles, and 1.8 - 2.2 moles respectively.

4. The preparation method according to claim 2, wherein, In step (1), the weight ratio of the medical alcohol to p-nonylphenol is 8 - 12:

1.

5. The preparation method according to claim 2, wherein In step (2), the heating reflux time is 1 - 4 h.

6. The application of the nitrogen foam sand washing and plug drilling fluid system according to claim 1 in the operation of sand washing and plug drilling in oil wells.

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