Leaking stoppage slurry for low-pressure malignant leakage formation as well as preparation method and application of leaking stoppage slurry

Abstract

The invention discloses leaking stoppage slurry for a low-pressure malignant leakage stratum. The leaking stoppage slurry is prepared from water, bentonite, xanthan gum, modified walnut shells, rubber particles and lignosulfonate. According to the dispersing type leaking stoppage slurry suitable for the low-density window, the leaking stoppage material walnut shells are modified, the dispersing performance of solid-phase particles in the leaking stoppage slurry is effectively improved, and therefore a good leaking stoppage effect can be achieved only through a small amount of modified walnut shells without adding a large amount of leaking stoppage materials; the plugging agent is very suitable for stratum plugging construction of low-density windows.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical preparations for petroleum drilling, and relates to a plugging slurry for low-pressure vicious leakage formations. The present invention also relates to a preparation method of the plugging slurry for low-pressure vicious leakage formations, and the present invention also relates to the application of the plugging slurry for low-pressure vicious leakage formations. Background Art

[0002] Low-pressure vicious leakage formation is one of the problems encountered in oil drilling. The drilling fluid density window of this low-pressure vicious leakage formation is low. The low-density window means that the density range of drilling fluid that can be selected during drilling a certain formation is very small. This situation is prone to drilling complications. The drilling fluid density exceeds this range, causing well leakage, and below this range causes the well wall to collapse and fall off. When encountering well leakage, it is often necessary to add plugging slurry for plugging operations. However, for the low-density window formation in the low-pressure vicious leakage formation, the plugging material in the plugging slurry should not be too much, otherwise the density of the plugging slurry will increase, and then the well wall will be fractured, causing more serious well leakage. This is because conventional plugging materials are prone to aggregation. Once aggregation occurs, the size of the plugging material becomes larger, and it cannot smoothly enter the formation cracks for plugging. At this time, new plugging materials need to be added again. The new plugging materials will still aggregate. In this vicious cycle, more and more new plugging materials are added, which greatly increases the density of the plugging slurry, which will cause more plugging and more leakage. Therefore, it is necessary to provide a plugging slurry for low-pressure vicious leakage formation to solve the above technical problems. Summary of the invention

[0003] The purpose of the present invention is to provide a plugging slurry for low-pressure vicious leakage formations, which solves the problem that conventional plugging slurries in the prior art are not easy to disperse, so that the more plugging occurs in low-pressure vicious leakage formations, the more leakage occurs.

[0004] Another object of the present invention is to provide a method for preparing the above-mentioned plugging slurry for low-pressure vicious leakage formations.

[0005] Another object of the present invention is to provide the application of the above-mentioned plugging slurry for low-pressure vicious leakage formation.

[0006] The technical solution adopted by the present invention is that the plugging slurry used for low-pressure vicious leakage formation is composed of the following components: based on 100 parts by weight of water, 3 to 6 parts by weight of bentonite, 5 to 8 parts by weight of xanthan gum, 14 to 16 parts by weight of modified walnut shells, 8 to 10 parts by weight of rubber particles, and 6 to 9 parts by weight of lignin sulfonate.

[0007] The present invention is also characterized in that:

[0008] The preparation method of modified walnut shell is:

[0009] S1, grinding walnut shells and passing through an 80-mesh sieve to obtain walnut shell powder;

[0010] S2, soaking the walnut shell powder obtained in step S1 in anhydrous ethanol, heating and stirring, then taking it out, washing it with deionized water and draining it to obtain a first treated product;

[0011] S3, injecting deionized water into the container, dripping hydrochloric acid solution to adjust the pH value to 4-5, adding silane coupling agent, placing the first treated product obtained in step S2 into the container, heating and stirring, then taking it out, washing it with deionized water and draining it, to obtain a second treated product;

[0012] S4, mixing the second treated product with polyethylene and ball milling to obtain a third treated product;

[0013] S5, placing the third processed product into an oven for baking to obtain a fourth processed product;

[0014] S6. Grind the fourth processed product and pass it through a 60-mesh sieve to obtain.

[0015] In step S2, the heating temperature is 40-50°C and the stirring time is 10-15 minutes.

[0016] In step S3, the mass ratio of the first treated material to the silane coupling agent is 1:0.4-0.6.

[0017] In step S3, the heating temperature is 60-70°C and the stirring time is 20-30 minutes.

[0018] In step S4, the second treated material: polyethylene = 1:2-2.4.

[0019] In step S5, the baking temperature is 100-110° C., and the baking time is 80-100 minutes.

[0020] Another technical solution adopted by the present invention is a method for preparing a plugging slurry for low-pressure vicious leakage formations, and the preparation method is as follows:

[0021] S101: Based on 100 parts by weight of water, 3 to 6 parts by weight of bentonite, 5 to 8 parts by weight of xanthan gum, 14 to 16 parts by weight of modified walnut shells, 8 to 10 parts by weight of rubber particles, and 6 to 9 parts by weight of lignin sulfonate are weighed respectively;

[0022] S201: Mix the ingredients weighed in S101, and then stir to obtain the mixture.

[0023] The present invention is also characterized in that it is used for plugging leakage in low-pressure vicious leakage formations and for plugging leakage in oil and gas wells with low safety density drilling fluid windows.

[0024] The beneficial effects of the present invention are:

[0025] The plugging slurry for low-pressure vicious leakage formations provided by the present invention is prepared by modifying the plugging material walnut shells. First, the oil and sugar in the walnut shells are removed by soaking in anhydrous ethanol to prevent the aggregation of walnut shell particles. Then, the silanol generated by the dissolution of the silane coupling agent reacts with the OH group on the walnut shell to generate Si-O-Si and Si-OC bonds, so that the clay in the plugging slurry is hardened to a certain extent, thereby reducing its viscosity and effectively preventing the aggregation of solid phase particles in the plugging slurry. Finally, polyethylene is used to perform hydrophobic treatment on the surface of the walnut shell powder to further prevent the aggregation of particles, thereby effectively improving the dispersion performance of the solid phase particles in the plugging slurry. Therefore, there is no need to add a large amount of plugging material, and only a small amount of modified walnut shells are needed to achieve a good plugging effect. The slurry is very suitable for plugging construction of formations with low-density windows. DETAILED DESCRIPTION

[0026] The present invention is described in detail below in conjunction with specific implementation modes.

[0027] The plugging slurry for low-pressure vicious leakage formation is composed of the following components: based on 100 parts by weight of water, 3 to 6 parts by weight of bentonite, 5 to 8 parts by weight of xanthan gum, 14 to 16 parts by weight of modified walnut shells, 8 to 10 parts by weight of rubber particles, and 6 to 9 parts by weight of lignin sulfonate.

[0028] The preparation method of modified walnut shell is:

[0029] S1, grinding walnut shells and passing through an 80-mesh sieve to obtain walnut shell powder;

[0030] S2, soaking the walnut shell powder obtained in step S1 in anhydrous ethanol, heating and stirring, then taking it out, washing it with deionized water and draining it to obtain a first treated product. The purpose of this step is to remove oil and sugar in the walnut shell to prevent aggregation between walnut shell particles;

[0031] S3, inject deionized water into the container, drip hydrochloric acid solution to adjust the pH value to 4-5, add silane coupling agent, the role of this step is that the silanol generated after the silane coupling agent is dissolved reacts with the OH group on the walnut shell to form Si-O-Si and Si-OC bonds, so that the clay in the plugging slurry is hardened to a certain extent, thereby reducing its viscosity, which can effectively prevent the solid phase particles in the plugging slurry from agglomerating, and the first treated product obtained in step S2 is placed in a container, heated and stirred, and then taken out, washed with deionized water and drained to obtain a second treated product;

[0032] S4, mixing the second treated material with polyethylene and ball milling to obtain a third treated material. The purpose of this step is to use polyethylene to perform hydrophobic treatment on the surface of the walnut shell powder to further prevent particle aggregation, thereby effectively improving the dispersion performance of solid phase particles in the plugging slurry;

[0033] S5, placing the third processed product into an oven for baking to obtain a fourth processed product;

[0034] S6. Grind the fourth processed product and pass it through a 60-mesh sieve to obtain.

[0035] In step S2, the heating temperature is 40-50°C and the stirring time is 10-15 minutes.

[0036] In step S3, the mass ratio of the first treated material to the silane coupling agent is 1:0.4-0.6.

[0037] In step S3, the heating temperature is 60-70°C and the stirring time is 20-30 minutes.

[0038] In step S4, the second treated material: polyethylene = 1:2-2.4.

[0039] In step S5, the baking temperature is 100-110° C., and the baking time is 80-100 minutes.

[0040] A method for preparing plugging slurry for low-pressure vicious leakage formation, the preparation method is as follows:

[0041] S101: Based on 100 parts by weight of water, 3 to 6 parts by weight of bentonite, 5 to 8 parts by weight of xanthan gum, 14 to 16 parts by weight of modified walnut shells, 8 to 10 parts by weight of rubber particles, and 6 to 9 parts by weight of lignin sulfonate are weighed respectively;

[0042] S201: Mix the ingredients weighed in S101, and then stir to obtain the mixture.

[0043] The application of plugging slurry in low-pressure vicious leakage formation is used to plug the leakage of oil and gas wells with low safety density drilling fluid window.

[0044] Example 1

[0045] Put 100 parts by weight of water in an enamel measuring cup, add 6 parts by weight of bentonite, 8 parts by weight of xanthan gum, 16 parts by weight of modified walnut shell G1, 10 parts by weight of rubber particles and 9 parts by weight of lignin sulfonate into the water, and stir to obtain plugging slurry A1 for low-pressure vicious leakage formations.

[0046] The preparation of modified walnut shell G1 is as follows:

[0047] S1, grinding walnut shells and passing through an 80-mesh sieve to obtain walnut shell powder;

[0048] S2, soaking the walnut shell powder obtained in step S1 in anhydrous ethanol, heating to 45° C. and stirring for 13 minutes, taking out, washing with deionized water and draining, to obtain a first treated product;

[0049] S3, inject deionized water into the three-necked flask, add hydrochloric acid solution to adjust the pH value to 4.5, add silane coupling agent, put the first treated product obtained in step S2 into the three-necked flask, and the mass ratio of the first treated product to the silane coupling agent is 1:0.5, heat to 65°C and stir for 25 minutes, take out, wash with deionized water and drain, and obtain the second treated product;

[0050] S4, placing the second treated product and polyethylene in a mass ratio of 1:2.2 in a planetary ball mill for mixing and ball milling to obtain a third treated product;

[0051] S5, placing the third processed product in a boat, placing it in an oven at 105° C. for 90 minutes, to obtain a fourth processed product in a block form;

[0052] S6. Grind the fourth processed product and pass it through a 60-mesh sieve to obtain modified walnut shell G1.

[0053] Example 2

[0054] Place 100 parts by weight of water in an enamel measuring cup, add 6 parts by weight of bentonite, 8 parts by weight of xanthan gum, 16 parts by weight of modified walnut shell G2, 10 parts by weight of rubber particles and 9 parts by weight of lignin sulfonate into the water, and stir to obtain plugging slurry A2 for low-pressure vicious leakage formations.

[0055] The preparation of modified walnut shell G2 is as follows:

[0056] S1, grinding walnut shells and passing through an 80-mesh sieve to obtain walnut shell powder;

[0057] S2, soaking the walnut shell powder obtained in step S1 in anhydrous ethanol, heating to 40° C. and stirring for 10 minutes, taking out, washing with deionized water and draining, to obtain a first treated product;

[0058] S3, inject deionized water into the three-necked flask, drip hydrochloric acid solution to adjust the pH value to 4, add silane coupling agent, put the first treated product obtained in step S2 into the three-necked flask, and the mass ratio of the first treated product to the silane coupling agent is 1:0.4, heat to 60°C and stir for 20 minutes, take out, wash with deionized water and drain, and obtain the second treated product;

[0059] S4, placing the second treated product and polyethylene in a mass ratio of 1:2 in a planetary ball mill for mixing and ball milling to obtain a third treated product;

[0060] S5, placing the third processed product in a boat, placing it in an oven at 100° C. for 80 minutes, to obtain a fourth processed product in a block form;

[0061] S6. Grind the fourth processed product and pass it through a 60-mesh sieve to obtain modified walnut shell G2.

[0062] Example 3

[0063] Place 100 parts by weight of water in an enamel measuring cup, add 6 parts by weight of bentonite, 8 parts by weight of xanthan gum, 16 parts by weight of modified walnut shell G3, 10 parts by weight of rubber particles and 9 parts by weight of lignin sulfonate into the water, and stir to obtain plugging slurry A3 for low-pressure vicious leakage formations.

[0064] The preparation of modified walnut shell G3 is as follows:

[0065] S1, grinding walnut shells and passing through an 80-mesh sieve to obtain walnut shell powder;

[0066] S2, soaking the walnut shell powder obtained in step S1 in anhydrous ethanol, heating to 50° C. and stirring for 15 minutes, taking out, washing with deionized water and draining, to obtain a first treated product;

[0067] S3, inject deionized water into the three-necked flask, drip hydrochloric acid solution to adjust the pH value to 5, add silane coupling agent, put the first treated product obtained in step S2 into the three-necked flask, and the mass ratio of the first treated product to the silane coupling agent is 1:0.6, heat to 70°C and stir for 30 minutes, take out, wash with deionized water and drain, and obtain the second treated product;

[0068] S4, placing the second treated product and polyethylene in a mass ratio of 1:2.4 in a planetary ball mill for mixing and ball milling to obtain a third treated product;

[0069] S5, placing the third processed product in a boat, placing it in an oven at 110° C. and baking it for 100 minutes to obtain a fourth processed product in a block form;

[0070] S6. Grind the fourth processed product and pass it through a 60-mesh sieve to obtain modified walnut shell G3.

[0071] Example 4

[0072] Place 100 parts by weight of water in an enamel measuring cup, add 6 parts by weight of bentonite, 8 parts by weight of xanthan gum, 16 parts by weight of modified walnut shell G4, 10 parts by weight of rubber particles and 9 parts by weight of lignin sulfonate into the water, and stir to obtain plugging slurry A4 for low-pressure vicious leakage formations.

[0073] The preparation of modified walnut shell G4 is as follows:

[0074] S1, grinding walnut shells and passing through an 80-mesh sieve to obtain walnut shell powder;

[0075] S2, soaking the walnut shell powder obtained in step S1 in anhydrous ethanol, heating to 43° C. and stirring for 12 minutes, taking out, washing with deionized water and draining, to obtain a first treated product;

[0076] S3, inject deionized water into the three-necked flask, drip hydrochloric acid solution to adjust the pH value to 4.3, add silane coupling agent, put the first treated product obtained in step S2 into the three-necked flask, and the mass ratio of the first treated product to the silane coupling agent is 1:0.45, heat to 63°C and stir for 23 minutes, take out, wash with deionized water and drain, and obtain the second treated product;

[0077] S4, placing the second treated product and polyethylene in a mass ratio of 1:2.1 in a planetary ball mill for mixing and ball milling to obtain a third treated product;

[0078] S5, placing the third processed product in a boat, placing it in an oven at 103° C. and baking it for 85 minutes to obtain a fourth processed product in a block form;

[0079] S6. Grind the fourth processed product and pass it through a 60-mesh sieve to obtain modified walnut shell G3.

[0080] Comparative Example 1

[0081] Except for the modified walnut, the other features are the same as those in Example 1, and ordinary walnut shells (particle size of 60 mesh, the addition amount is also 16 parts by weight) are used to replace the modified walnut shells, and finally the plugging slurry D1 is obtained.

[0082] Comparative Example 2

[0083] Except for the modified walnut, the other features are the same as those of Example 2, and ordinary walnut shells (particle size of 60 mesh, added in an amount of 60 parts by weight) are used instead of the modified walnut shells to finally obtain the plugging slurry D2.

[0084] The plugging performance of the plugging slurry obtained in the above embodiments and comparative examples was tested using a QD-2 plugging instrument (the length of the slit plate was 30 mm and the width was 1 mm). The results are as follows:

[0085]

[0086]

[0087] It can be seen from the data in the above table that the plugging slurry for low-pressure vicious leakage formations prepared by the method provided by the present invention can form a plugging layer with a pressure bearing capacity of more than 6MPa when a small amount of plugging material is used. However, if ordinary walnut shells are used as plugging materials, a large amount of them needs to be added to achieve the same plugging effect. However, if the amount is large, the density of the plugging slurry will inevitably increase. Therefore, ordinary walnut shells are not suitable for plugging formations with low-density windows.

Claims

1. A plugging slurry for low-pressure vicious leakage formation, characterized in that: The invention is composed of the following components: based on 100 parts by weight of water, 3 to 6 parts by weight of bentonite, 5 to 8 parts by weight of xanthan gum, 14 to 16 parts by weight of modified walnut shells, 8 to 10 parts by weight of rubber particles and 6 to 9 parts by weight of lignin sulfonate.

2. The plugging slurry for low-pressure vicious leakage formation according to claim 1 is characterized in that: The preparation method of the modified walnut shell is: S1, grinding walnut shells and passing through an 80-mesh sieve to obtain walnut shell powder; S2, soaking the walnut shell powder obtained in step S1 in anhydrous ethanol, heating and stirring, then taking it out, washing it with deionized water and draining it to obtain a first treated product; S3, injecting deionized water into the container, dripping hydrochloric acid solution to adjust the pH value to 4-5, adding silane coupling agent, placing the first treated product obtained in step S2 into the container, heating and stirring, then taking it out, washing it with deionized water and draining it, to obtain a second treated product; S4, mixing the second treated product with polyethylene and ball milling to obtain a third treated product; S5, placing the third processed product into an oven for baking to obtain a fourth processed product; S6. Grind the fourth processed product and pass it through a 60-mesh sieve to obtain.

3. The plugging slurry for low-pressure vicious leakage formation according to claim 2 is characterized in that: In step S2, the heating temperature is 40-50°C and the stirring time is 10-15 minutes.

4. The plugging slurry for low-pressure vicious leakage formation according to claim 2 is characterized in that: In step S3, the mass ratio of the first treated material to the silane coupling agent is 1:0.4-0.

6.

5. The plugging slurry for low-pressure vicious leakage formation according to claim 2 is characterized in that: In step S3, the heating temperature is 60-70°C and the stirring time is 20-30 minutes.

6. The plugging slurry for low-pressure vicious leakage formation according to claim 2, characterized in that: In step S4, the second treated material: polyethylene = 1:2-2.

4.

7. The plugging slurry for low-pressure vicious leakage formation according to claim 2 is characterized in that: In step S5, the baking temperature is 100-110° C., and the baking time is 80-100 minutes.

8. A method for preparing a plugging slurry for low-pressure vicious leakage formations, characterized in that: The preparation method is as follows: S101: Based on 100 parts by weight of water, 3 to 6 parts by weight of bentonite, 5 to 8 parts by weight of xanthan gum, 14 to 16 parts by weight of modified walnut shells, 8 to 10 parts by weight of rubber particles, and 6 to 9 parts by weight of lignin sulfonate are weighed respectively; S201: Mix the ingredients weighed in S101, and then stir to obtain the mixture.

9. The application of the plugging slurry for low-pressure vicious leakage formation according to claim 1 is characterized in that: Used for plugging leaks in oil and gas wells with low safety density drilling fluid window.

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