DOUBLE-RESPONSE SELF-DEGRADABLE TEMPORARY PLUGGING AGENT AND PREPARATION METHOD THEREOF

Abstract

The present disclosure relates to a double-response self-degradable temporary plugging agent and a preparation method thereof. The double-response self-degradable temporary plugging agent is prepared by compounding a crosslinkable monomer with a temperature-sensitive degradablity and an inorganic material with an acid solubility with a first monomer, a dispersant, an initiator and water, and subjecting the resulting mixture to a polymerization.

Claims

1. A double-response self-degradable temporary plugging agent, which is prepared by polymerization of raw materials comprising, in parts by weight, 32 parts of a monomer, 1-5 parts of a reinforcing agent, 0.1-0.6 parts of a dispersant, 0.07-0.12 parts of an initiator, 2-10 parts of a hydrophobic nano-powder and 60-90 parts of water, wherein the monomer comprises a first monomer and a second monomer, wherein the first monomer is at least one selected from the group consisting of a propylene monomer, a styrene monomer, itaconic acid, acrylic acid and maleic anhydride, and the second monomer is a temperature-sensitive degradable crosslinkable monomer, being at least one selected from the group consisting of 1,4-butanediol dimethacrylate, ethylene dimethacrylate and a poly(ethylene glycol) diacrylate; and the reinforcing agent is an acid-sensitive inorganic material.

2. The double-response self-degradable temporary plugging agent as claimed in claim 1, wherein the hydrophobic nano-powder is at least one selected from the group consisting of a hydrophobic nano-SiO.sub.2 and a hydrophobic nano-TiO.sub.2.

3. The double-response self-degradable temporary plugging agent as claimed in claim 1, wherein the first monomer is at least one selected from the group consisting of acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, sodium methylallyl sulfonate, methacrylatoethyl trimethyl ammonium chloride, sodium p-styrenesulfonate, diallyldimethylammonium chloride, itaconic acid, acrylic acid and maleic anhydride.

4. The double-response self-degradable temporary plugging agent as claimed in claim 1, wherein the dispersant is at least one selected from the group consisting of a poly(vinyl alcohol), a polyacrylamide, a partially hydrolyzed polyacrylamide and a salt-resistant polyacrylamide KYPAM.

5. The double-response self-degradable temporary plugging agent as claimed in claim 1, wherein the reinforcing agent is at least one selected from the group consisting of a soluble starch, a nano-calcium carbonate, a chitosan and calcium stearate.

6. The double-response self-degradable temporary plugging agent as claimed in claim 1, wherein the initiator is at least one selected from the group consisting of ammonium persulfate, potassium persulfate, sodium thiosulfate, sodium bisulfate and 2,2′-azobis(2-methylpropionamidine) dihydrochloride.

7. A method for preparing a double-response self-degradable temporary plugging agent, comprising, weighing each raw material of a composition of the double-response self-degradable temporary plugging agent; dissolving a first monomer, a second monomer, a dispersant, a reinforcing agent, a hydrophobic nano-powder and an initiator in water to obtain a liquid mixture, and stirring the liquid mixture, to obtain a dried mixture; and subjecting the dried mixture to a polymerization at a temperature of 30-60° C., to obtain a dry powdery microsphere including the double-response self-degradable temporary plugging agent.

8. The method as claimed in claim 7, wherein stirring the liquid mixture is performed at a rate of 3000-20000 r/min for 0.5-5 min.

9. The double-response self-degradable temporary plugging agent as claimed in claim 2, wherein the first monomer is at least one selected from the group consisting of acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, sodium methylallyl sulfonate, methacrylatoethyl trimethyl ammonium chloride, sodium p-styrenesulfonate, diallyldimethylammonium chloride, itaconic acid, acrylic acid and maleic anhydride.

10. The double-response self-degradable temporary plugging agent as claimed in claim 2, wherein the dispersant is at least one selected from the group consisting of a poly(vinyl alcohol), a polyacrylamide, a partially hydrolyzed polyacrylamide and a salt-resistant polyacrylamide KYPAM.

11. The double-response self-degradable temporary plugging agent as claimed in claim 2, wherein the reinforcing agent is at least one selected from the group consisting of a soluble starch, a nano-calcium carbonate, a chitosan and calcium stearate.

12. The double-response self-degradable temporary plugging agent as claimed in claim 2, wherein the initiator is at least one selected from the group consisting of ammonium persulfate, potassium persulfate, sodium thiosulfate, sodium bisulfate and 2,2′-azobis(2-methylpropionamidine) dihydrochloride.

13. A method for preparing the double-response self-degradable temporary plugging agent as claimed in claim 1, comprising, weighing each raw material according to the composition of the double-response self-degradable temporary plugging agent as claimed in claim 1; dissolving the first monomer, the second monomer, the dispersant, the reinforcing agent, the hydrophobic nano-powder and the initiator in water to obtain a liquid mixture, and stirring the liquid mixture, to obtain a dried mixture; and subjecting the dried mixture to a polymerization at a temperature of 30-60° C., to obtain a dry powdery microsphere including the double-response self-degradable temporary plugging agent.

14. The method as claimed in claim 13, wherein stirring the liquid mixture is performed at a rate of 3000-20000 r/min for 0.5-5 min.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG. 1 shows a micrograph of the double-response self-degradable temporary plugging agent according to Example 1 of the present disclosure.

[0022] FIG. 2 is a diagram illustrating particle size test of the double-response self-degradable temporary plugging agent according to Example 4 of the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] The principles and features of the present disclosure will be described below with reference to the accompanying drawings, and the examples are only used to explain the present disclosure, but not to limit the scope of the present disclosure. Unless otherwise defined, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art.

[0024] Raw Materials

[0025] Polyethylene glycol (200) diacrylate and polyethylene glycol (600) diacrylate were purchased from Shanghai King Chemical Co., Ltd., China, with a weight-average molecular weight of 400-800.

[0026] Salt-resistant polyacrylamide was purchased from Beijing Hengju Chemical group Co., Ltd., China, with a weight-average molecular weight of 25 million and a hydrolysis degree of 30%.

[0027] Ethylene dimethacrylate was purchased from Jinan Jinrihe Chemical Co., Ltd., China.

[0028] 1,4-Butanediol dimethacrylate was purchased from Fushun Anxin Chemistry Co., Ltd., China, with a content of 99.0%.

[0029] Polyacrylamide was purchased from Aladdin, with a weight-average molecular weight of 15 million and a hydrolysis degree of lower than 1%.

[0030] Ethylene dimethacrylate was purchased from Jinan Jinrihe Chemical Co., Ltd., China.

[0031] Poly(vinyl alcohol) 2488 was purchased from Henan Mingcheng Chemical Co., Ltd., China, with a weight-average molecular weight of 101200-110000.

[0032] Salt-resistant polyacrylamide KYPAM was purchased from Beijing Hengju Chemical group Co., Ltd., China, with a weight-average molecular weight of 19-22 million and a hydrolysis degree of 25-30%.

[0033] Hydrophobic SiO.sub.2-GW100 was purchased from Jiangxi Huiming Chemical Co., Ltd., China, with a specific surface area of 207 m.sup.2/g.

[0034] Hydrophobic TiO.sub.2 was purchased from Xuancheng Jing Rui New Material Co., Ltd., with an average particle diameter of 30 nm.

[0035] Hydrophobic SiO.sub.2-D10 was purchased from Evonik Degussa, with a specific surface area of 90 m.sup.2/g.

[0036] Other regents were conventional commercial products.

EXAMPLE 1

[0037] The present example provided a double-response self-degradable temporary plugging agent, the raw materials composition of which was shown in Table 1 below:

TABLE-US-00001 TABLE 1 The raw materials composition of the double-response self-degradable temporary plugging agent according to Example 1 Composition Name of the specific raw materials Amount Monomer Acrylamide 25 g Polyethylene glycol (200) diacrylate 0.2 g (with an average molecular weight of 600) Dispersant Salt-resistant polyacrylamide 0.15 g Reinforcing Nano-calcium carbonate 3 g agent Initiator Potassium persulfate 0.08 g Sodium bisulfite 0.04 g Water Deionized water 80 g

[0038] The method for preparing the double-response self-degradable temporary plugging agent of the present example was performed according to the following procedures:

[0039] Step 1: each raw material was weighted according to Table 1.

[0040] Step 2: the monomer, the dispersant, the reinforcing agent and the initiator were added into water to obtain a liquid mixture, and the liquid mixture was placed in a water bath and polymerized at a temperature of 35° C. for 2 h, to obtain a jellylike product; the jellylike product was cut into pieces, put into an oven and dried at 50° C., and then crushed, obtaining a powder temporary plugging agent product. The micro-morphology of the product was detected, and the result was shown in FIG. 1. It can be seen that the product was irregular solid particles with an uneven particle size, and the maximum particle size was about 70-80 μm, the minimum particle size was about 20-30 μm, and the average particle size was about 60 μm.

EXAMPLE 2

[0041] The present example provided a double-response self-degradable temporary plugging agent, the raw materials composition of which was shown in Table 2 below:

TABLE-US-00002 TABLE 2 The raw materials composition of the double-response self-degradable temporary plugging agent according to example 2 Composition Name of the specific raw materials Amount Monomer Acrylamide 10 g Acrylic acid 3 g 1,4-Butanediol dimethacrylate 0.3 g Dispersant Polyacrylamide 0.3 g Reinforcing Soluble starch 2 g agent Initiator Ammonium persulfate 0.06 g Sodium bisulfite 0.045 g Water Deionized water 85 g

[0042] The method for preparing the double-response self-degradable temporary plugging agent of the present example was basically the same as that in Example 1.

EXAMPLE 3

[0043] The present example provided a double-response self-degradable temporary plugging agent, the raw materials composition of which was shown in Table 3 below:

TABLE-US-00003 TABLE 3 The raw materials composition of the double-response self-degradable temporary plugging agent according to Example 3 Composition Name of the specific raw materials Amount Monomer Acrylamide 25 g 2-Acrylamide-2-methylpropanesulfonic acid 5 g Ethylene dimethacrylate 1 g Dispersant Poly(vinyl alcohol) 2488 0.5 g Reinforcing Chitosan 1 g agent Initiator Ammonium persulfate 0.06 g Sodium bisulfite 0.045 g Water Deionized water 70 g

[0044] The method for preparing the double-response self-degradable temporary plugging agent of the present example was basically the same as that in Example 1.

EXAMPLE 4

[0045] The present example provided a double-response self-degradable temporary plugging agent, the raw materials composition of which was shown in Table 4 below:

TABLE-US-00004 TABLE 4 The raw materials composition of the double-response self-degradable temporary plugging agent according to Example 4 Composition Name of the specific raw materials Amount Monomer Acrylamide 20 g Sodium p-styrenesulfonate 1 g Polyethylene glycol (200) diacrylate 0.3 g (with an average molecular weight of 400) Dispersant Salt-resistant polyacrylamide KYPAM 0.2 g Reinforcing Nano-calcium carbonate 5 g agent Hydrophobic Hydrophobic SiO.sub.2-GW100 3 g nano-powder Initiator Ammonium persulfate 0.036 g Sodium bisulfite 0.03 g Water Deionized water 79 g

[0046] The method for preparing the double-response self-degradable temporary plugging agent of the present example was performed according to the following procedures:

[0047] Step 1, each raw material was weighted according to Table 4.

[0048] Step 2, the monomer, the dispersant, the reinforcing agent, the hydrophobic nano-powder and the initiator were added into water to obtain a liquid mixture, the liquid mixture was stirred at 10000 r/min for 100 s, and then placed in a water bath and polymerized at 35° C. for 2.5 hours, obtaining a powder temporary plugging agent product. The particle size distribution of the product was shown in FIG. 2, and the average particle size thereof was 20.6 μm.

EXAMPLE 5

[0049] The present example provided a double-response self-degradable temporary plugging agent, the raw materials composition of which was shown in Table 5 below:

TABLE-US-00005 TABLE 5 The raw materials composition of the double-response self-degradable temporary plugging agent according to Example 5 Composition Name of the specific raw materials Amount Monomer Acrylamide 30 g Itaconic acid 5 g Ethylene dimethacrylate 0.5 g Dispersant Salt-resistant polyacrylamide KYPAM 0.2 g Reinforcing Calcium stearate 2 g agent Hydrophobic Hydrophobic SiO.sub.2-D10 5 g nano-powder Initiator Potassium persulfate 0.05 g Sodium bisulfite 0.036 g Water Deionized water 65 g

[0050] The method for preparing the double-response self-degradable temporary plugging agent of the present example was basically the same as that in Example 4.

EXAMPLE 6

[0051] The present example provided a double-response self-degradable temporary plugging agent, the raw materials composition of which was shown in Table 6 below:

TABLE-US-00006 TABLE 6 The raw materials composition of the double-response self-degradable temporary plugging agent according to Example 6 Composition Name of the specific raw materials Amount Monomer Acrylamide 15 g Methacrylatoethyl trimethyl ammonium 2 g chloride polyethylene glycol (600) diacrylate 0.7 g (with an average molecular weight of 800) Dispersant Salt-resistant polyacrylamide KYPAM 0.2 g Reinforcing Chitosan 2.5 g agent Hydrophobic Hydrophobic TiO.sub.2 7 g nano-powder Initiator Potassium persulfate 0.05 g Sodium bisulfite 0.036 g Water Deionized water 85 g

[0052] The method for preparing the double-response self-degradable temporary plugging agent of the present example was basically the same as that in Example 4.

[0053] Performance Test

[0054] 1. Degradability in Acid

[0055] 0.5 g of the temporary plugging agents of Examples 1 to 3 were respectively added into 15% HCl for degradation test. The degradation results at 60° C., 70° C., 80° C., 90° C. and 120° C. were observed.

[0056] 0.5 g of the temporary plugging agents of Examples 4 to 6 were added into a mixed acid solution of 12% HCl and 3% HF for degradation test. The degradation results at 60° C., 70° C., 80° C. and 90° C. were observed. The time required for complete degradation under different temperature conditions was shown in Table 7 below:

TABLE-US-00007 TABLE 7 Statistical table of results of acid degradation test Time required for complete degradation under different temperature conditions (h) Example No. 60° C. 70° C. 80° C. 90° C. 120° C. Example 1 240 128 96 48 2.5 Example 2 248 132 103 46 3 Example 3 235 125 90 42 2 Example 4 255 134 108 50 2.5 Example 5 260 138 110 56 3.5 Example 6 266 140 115 58 4.5

[0057] It can be seen from Table 7 that the temporary plugging agents of Examples 1-6 could be degraded in HCl or mixed acid of 12% HCl and 3% HF, and the higher the temperature, the faster the degradation.

[0058] 2. Plugging Performance Test

[0059] The plugging performance and damage performance of the temporary plugging agents of Examples 1-6 to fractured cores with a crack width of 0.5 mm were investigated by a single-tube core physical model experiment.

[0060] The specific experimental process were as follows:

[0061] (1) the fractured core was dried at a low temperature, and the diameter, length, dry weight and fracture width of the core were measured;

[0062] (2) the core were loaded into a core holder, and a simulated formation water was injected thereto at a certain flow rate by a constant-flux pump until the pressure was stable, wherein the composition of the simulated formation water were shown in Table 8; the flow rate and pressure were recorded to calculate a permeability K.sub.1;

TABLE-US-00008 TABLE 8 Composition of the simulated formation water Total Concentration of ions contained therein (mg/L) salinity K.sup.+ + Na.sup.+ Ca.sup.2+ Mg.sup.2+ Cl.sup.− SO.sub.4.sup.2− HCO.sub.3.sup.2− CO.sub.3.sup.2− (mg/L) 4059.3 163.2 150.5 4294.5 1587.8 1510.9 36.7 11802.9

[0063] (3) 0.4 PV of the temporary plugging agent was injected to the fractured cores and aged at 60° C. for 3 days, and a water flooding was carried out until the pressure was stable; the flow rate and pressure were recorded to calculate a permeability K.sub.2; a plugging rate η was calculated according to η=(K.sub.1−K.sub.2)/K.sub.1×100%, and the results were shown in Table 9:

TABLE-US-00009 TABLE 9 Statistical table of results of the plugging test Permeability/μm.sup.2 Plugging Breakthrough Example No. K.sub.1 K.sub.2 rate η/% pressure/MPa Example 1 1.40 0.26 81.23 5.1 Example 2 1.72 0.50 70.71 4.5 Example 3 1.64 0.21 86.90 5.8 Example 4 1.59 0.29 82.44 4.8 Example 5 1.51 0.27 80.2 5.5 Example 6 1.61 0.15 90.6 6.3

[0064] It can be seen from Table 8 that the plugging rate of the temporary plugging agents of Examples 1-6 to fractured cores reached over 70%, and that of Example 6 reached over 90%, showing that the temporary plugging agents have good plugging ability.

[0065] 3. Damage Performance Test

[0066] Damage performance test was performed by a method similar to that for plugging performance test, except that the water flooding in step (2) was replaced with acid injection (15% HCl), followed by a water flooding, and then a permeability K.sub.3 was calculated.

[0067] Damage rate R was calculated according to R=(K.sub.1−K.sub.3)/K.sub.1×100%, and the statistical results were shown in Table 9:

TABLE-US-00010 TABLE 10 Statistical table of results of damage test to core Permeability/μm.sup.2 Example No. K.sub.1 K.sub.3 Damage rate/% Example 1 1.42 1.35 5.23 Example 2 1.83 1.70 6.71 Example 3 1.66 1.54 6.90 Example 4 1.45 1.37 5.4 Example 5 1.88 1.69 8.2 Example 6 1.68 1.60 4.6

[0068] It can be seen from Table 10 that the damage rates of the temporary plugging agents of Examples 1-6 to fractured cores were all below 10%, and the minimum damage rate was only 4.6%, showing that the temporary plugging agents have less damage to cores through self-degradation.

[0069] The technical features of the above embodiments could be combined arbitrarily. In order to make the description concise, possible combinations of the technical features in the above embodiments are not all described herein. However, as long as there is no contradiction between the combinations of these technical features, they should be considered as the scope recorded in this specification.

[0070] The above embodiments are merely preferred embodiments of the present disclosure, but not intended to limit the present disclosure. Any modifications, equivalent replacements, improvements and the like made within the spirit and principle of the present disclosure should fall within the protection scope of the present disclosure.