A plugging removal composition and use thereof

Abstract

The application provides a plugging removal composition and application thereof. The plugging removal composition mainly comprises an oxidizing agent, an activator, a stabilizer and a complexing agent, and further comprises a solvent. The plugging removal composition provided by the application has good plugging removal effect on polymer gel: the 10-day plugging removal rate of the plugging removal composition on polymer gel prepared from polyacrylamide, a phenolic aldehyde crosslinking system and simulated mineralized water with a mineralization degree of 218000 mg / L is 87.33% to 98.73%, the highest 10-day plugging removal rate is more than 98%, and the plugging removal composition can effectively remove polymer gel under high temperature of 110 DEG C and mineralization degree of 0 to 218000 mg / L.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of polymer gel plug-removing, and particularly relates to a plug-removing composition and application thereof. BACKGROUND

[0002] In order to effectively alleviate the pressure of oil supply and ensure the stable production of old oil fields, the polymer water plugging technology has been applied in the industrialization in Daqing, Shengli and other oil fields. The application of gel can significantly reduce the permeability of fractures and high permeable flow zones, make the seepage process more effective, and effectively solve the problems of high water content and low recovery rate of oil wells. This technology plays an important role in improving the ultimate recovery rate of oil fields, maintaining stable production of oil fields and improving the development effect of oil fields in high water cut period. However, with the increase of water plugging times, new problems of oil field production become more and more prominent. The application of gel may cause injection pipe blockage, wellbore pollution caused by water plugging of immobile pipe column, high injection pressure, and injection of plugging agent, etc. Even it may invade porous formation and cause formation damage.

[0003] At present, the horizontal well of clastic rock reservoir has multiple times of water plugging, 117 well times, accounting for nearly 40%. The water plugging of immobile pipe column has problems of wellbore pollution, high injection pressure and injection of plugging agent. With the gradual harshness of formation conditions, it is of great significance to develop corresponding high-performance plugging-removing agent with temperature resistance and salt resistance. In recent years, research and application have been carried out in the direction of physical plugging removal, chemical plugging removal and biological plugging removal at home and abroad, and certain achievements have been made. However, the current research mainly focuses on the degradation of polymer molecules and the viscosity reduction of solution, which can better solve the problems of polymer entanglement and gel caused blockage. However, there is little research on the plugging removal of polymer gel and the plugging removal of polymer gel under harsh formation conditions. Various existing plugging removal technologies have certain limitations:

[0004] ①The application range of physical plugging removal technology is limited and it cannot act on deep well zone;

[0005] ②The biological plugging removal technology is only suitable for specific reservoirs due to the specificity of gel breaking enzyme, and the temperature resistance of gel breaking enzyme is insufficient, and the activity at high temperature is greatly reduced, resulting in poor plugging removal effect;

[0006] ③The chemical plugging removal technology has insufficient temperature resistance and salt resistance (90℃ / 100,000 mineralization degree), and it cannot effectively dredge under high temperature (110℃) conditions. Under high mineralization conditions, the solubility of the plugging removal agent is poor, and even it may cause blockage due to precipitation.

[0007] As can be seen from the above, the existing physical plugging removal technology, biological plugging removal technology and chemical plugging removal technology cannot realize the plugging removal of polymer gel under harsh formation environment of high temperature and high salt, so it is urgent to develop a plugging removal agent with high temperature resistance (110℃) and high salt resistance (21.8×10 4The polymer gel plugging agent with a concentration of 100-1000 mg / L provides a solution for plugging in high-temperature and high-salt reservoirs, solves the problems of pipeline blockage, wellbore pollution, excessively high injection pressure and injection failure after water plugging in high-temperature and high-salt reservoirs, improves the permeability of the plugged layer, and realizes the stable production of oilfield. SUMMARY

[0008] To solve the problem of lacking of the polymer gel plugging agent for effectively plugging the polymer gel in the high-temperature and high-salt environment in the prior art, the purpose of the present application is to provide a polymer gel plugging agent which can effectively plug the polymer gel in the environment with high temperature (110 DEG C) and high salt (21.8 x 10 4 mg / L).

[0009] To achieve the above purpose, the present application provides a plugging composition which comprises an oxidizing agent, an activator, a stabilizer and a complexing agent.

[0010] In one embodiment of the present application, the plugging composition further comprises a solvent.

[0011] In one embodiment of the present application, based on 100% of the mass of the plugging composition, the plugging composition comprises 6-12 wt% of the oxidizing agent, 0.3-0.6 wt% of the activator, 0.5-1 wt% of the stabilizer, 3 wt% of the complexing agent and the balance of the solvent.

[0012] In one embodiment of the present application, the oxidizing agent is a persulfate salt.

[0013] Preferably, the oxidizing agent is at least one selected from the group consisting of ammonium persulfate, potassium persulfate and sodium persulfate.

[0014] In one embodiment of the present application, the activator is sodium bisulfate.

[0015] In one embodiment of the present application, the stabilizer is sodium sulfamate and / or sodium carbonate.

[0016] Preferably, the stabilizer is a mixture of sodium sulfamate and sodium carbonate.

[0017] Preferably, the mass ratio of sodium carbonate to sodium sulfamate is 2:1.

[0018] In one embodiment of the present application, the complexing agent is an organic polybasic phosphoric acid complexing agent.

[0019] Preferably, the complexing agent is at least one selected from the group consisting of polyamino polyether-based methylene phosphonic acid (PAPEMP), hydroxyethylidene diphosphonic acid (HEDP) and 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTCA).

[0020] In one specific embodiment of the present application, the solvent is water or mineralized water.

[0021] Preferably, the mineralization degree of the solvent is 0 to 218000 mg / L.

[0022] The application of the plugging removal composition in polymer gel plugging removal, in particular as a polymer gel plugging removal agent.

[0023] In one specific embodiment of the present application, the temperature of the application is not lower than 110℃; and / or

[0024] The mineralization degree of the application ranges from 0 to 218000 mg / L.

[0025] The beneficial effects of the present application are:

[0026] In view of the problem in the prior art that there is a lack of plugging removal agents that can effectively remove polymer gel in high-temperature and high-salt environments, the present application provides a plugging removal composition and its application. The plugging removal composition provided by the present application mainly includes an oxidizing agent, an activator, a stabilizer and a complexing agent, and secondarily includes a solvent. The plugging removal composition has good high-temperature resistance and salt resistance, and strong plugging removal ability for polymer gel: at 110℃, the 10-day plugging removal rate of the plugging removal composition for polymer gel prepared from polyacrylamide, a phenolic crosslinking system (specifically a mixture of phenol and hexamethylenetetramine with a mass ratio of 1:1) and simulated mineralized water with a mineralization degree of 218100.55 mg / L after constant temperature aging at 110℃ for 24h is 87.33% to 98.73%, and the highest 10-day plugging removal rate is more than 98%, which can effectively remove polymer gel under the conditions of 110℃ and a mineralization degree of 0 to 218100.55 mg / L. Moreover, the raw materials of the plugging removal composition provided by the present application are easy to obtain, and the preparation method is simple, which is suitable for popularization and use. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 From left to right are the plugging removal situations of the plugging removal compositions prepared in Example 1, Example 3, Example 2 and Example 4 for polymer gel in the polymer gel plugging removal performance evaluation at an experimental time of 24h. DETAILED DESCRIPTION

[0028] The present application will be further described below in conjunction with examples, but the examples of the present application are only exemplary descriptions, and the embodiments do not constitute a limitation on the present application in any case.

[0029] Preparation of the plugging removal composition

[0030] The simulated mineralized water used in Examples 1 to 8 has a total mineralization degree of 218100.55 mg / L, wherein K ++ Na + 71634.37 mg / L, Ca 2+ 11272.5 mg / L, Mg 2+ 1161.84 mg / L, Cl - 133658 mg / L, SO4 2- 150 mg / L, HCO3 - 33.84 mg / L, I - 10 mg / L, Br - 180 mg / L.

[0031] In Example 1, 2, 5, 6 and Comparative Example 4, polyamino polyether methylene phosphonic acid (PAPEMP) was purchased from Shandong Taihe Science and Technology Co., Ltd.

[0032] In Example 7, 8, 2-phosphonobutane-1, 2, 4-tricarboxylic acid (PBTCA): purchased from Shandong Taihe Science and Technology Co., Ltd., CAS No. 37971-36-1;

[0033] In Example 3, 4, hydroxyethylidene diphosphonic acid (HEDP): purchased from Shandong Taihe Science and Technology Co., Ltd., CAS No. 2809-21-4.

[0034] Example 1

[0035] Take 6g sodium persulfate, 0.3g sodium bisulfate, 0.5g stabilizer (a mixture of sodium carbonate and sodium sulfamate with a mass ratio of 2:1), 3g polyamino polyether methylene phosphonic acid (PAPEMP) and 90.2g simulated mineralized water with a mineralization degree of 218100.55mg / L, stir at a speed of 300rpm for 5min, get the plugging removal composition.

[0036] Example 2

[0037] Take 12g sodium persulfate, 0.3g sodium bisulfate, 0.5g stabilizer (a mixture of sodium carbonate and sodium sulfamate with a mass ratio of 2:1), 3g polyamino polyether methylene phosphonic acid (PAPEMP) and 84.2g simulated mineralized water with a mineralization degree of 218100.55mg / L, stir at a speed of 300rpm for 5min, get the plugging removal composition.

[0038] Example 3

[0039] Take 6g of ammonium persulfate, 0.6g of sodium bisulfate, 0.5g of stabilizer (a mixture of sodium carbonate and sodium sulfamate with a mass ratio of 2:1), 3g of hydroxyethylidene diphosphonic acid (HEDP) and 89.9g of simulated mineralized water with a mineralization degree of 218100.55mg / L, stir at a speed of 300rpm for 5min, to obtain a plugging removal composition.

[0040] Example 4

[0041] Take 12g of potassium persulfate, 0.6g of sodium bisulfate, 0g of stabilizer (a mixture of sodium carbonate and sodium sulfamate with a mass ratio of 2:1), 3g of hydroxyethylidene diphosphonic acid (HEDP) and 83.9g of simulated mineralized water with a mineralization degree of 218100.55mg / L, stir at a speed of 300rpm for 5min, to obtain a plugging removal composition.

[0042] Example 5

[0043] Take 6g of ammonium persulfate, 0.3g of sodium bisulfate, 1g of stabilizer (a mixture of sodium carbonate and sodium sulfamate with a mass ratio of 2:1), 3g of polyamino polyether methylene phosphonic acid (PAPEMP) and 89.7g of simulated mineralized water with a mineralization degree of 218100.55mg / L, stir at a speed of 300rpm for 5min, to obtain a plugging removal composition.

[0044] Example 6

[0045] Take 12g of potassium persulfate, 0.3g of sodium bisulfate, 1g of stabilizer (a mixture of sodium carbonate and sodium sulfamate with a mass ratio of 2:1), 3g of polyamino polyether methylene phosphonic acid (PAPEMP) and 83.7g of simulated mineralized water with a mineralization degree of 218100.55mg / L, stir at a speed of 300rpm for 5min, to obtain a plugging removal composition.

[0046] Example 7

[0047] Take 6g of sodium persulfate, 0.6g of sodium bisulfate, 1g of stabilizer (a mixture of sodium carbonate and sodium sulfamate with a mass ratio of 2:1), 3g of 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTCA) and 89.4g of simulated mineralized water with a mineralization degree of 218100.55mg / L, stir at a speed of 300rpm for 5min, to obtain a plugging removal composition.

[0048] Example 8

[0049] Take 12 g of sodium persulfate, 0.6 g of sodium bisulfate, 1 g of stabilizer (a mixture of sodium carbonate and sodium sulfamate with a mass ratio of 2:1), 3 g of 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTCA), and 83.4 g of simulated mineralized water with a mineralization degree of 218100.55 mg / L, mix and stir at a speed of 300 rpm for 5 min to obtain a plugging removal composition.

[0050] Comparative Example 1

[0051] Take 6 g of sodium persulfate, 0.3 g of sodium bisulfate, and 93.7 g of simulated mineralized water with a mineralization degree of 218100.55 mg / L, mix and stir at a speed of 300 rpm for 5 min to obtain a plugging removal composition.

[0052] Comparative Example 2

[0053] Take 12 g of sodium persulfate, 0.3 g of sodium bisulfate, and 87.7 g of simulated mineralized water with a mineralization degree of 218100.55 mg / L, mix and stir at a speed of 300 rpm for 5 min to obtain a plugging removal composition.

[0054] Comparative Example 3

[0055] Take 6 g of sodium persulfate, 0.3 g of sodium bisulfate, 0.5 g of stabilizer (sodium carbonate: sodium sulfamate = 2:1), and 93.2 g of simulated mineralized water with a mineralization degree of 218100.55 mg / L, mix and stir at a speed of 300 rpm for 5 min to obtain a plugging removal composition.

[0056] Comparative Example 4

[0057] Take 6 g of sodium persulfate, 0.3 g of sodium bisulfate, 3 g of polyamino polyether-based methylene phosphonic acid (PAPEMP), and 90.7 g of simulated mineralized water with a mineralization degree of 218100.55 mg / L, mix and stir at a speed of 300 rpm for 5 min to obtain a plugging removal composition.

[0058] Evaluation of the polymer gel plugging removal performance of the plugging removal composition

[0059] The polymer gel was prepared according to the following method, and then the aged polymer gel was removed by the plugging removal composition, and the plugging removal rate was calculated to evaluate the plugging removal performance of the plugging removal composition prepared in Examples 1 to 8 and Comparative Examples 1 to 4 on the polymer gel. The specific experimental steps are as follows:

[0060] The simulated mineralized water used in this experiment has a total mineralization degree of 218100.55 mg / L, of which K + +Na + is 71634.37 mg / L, Ca 2+ is 11272.5 mg / L, and Mg 2+Na2SO4 - Na2SO4 2- Na2SO4 - Na2SO4 - Na2SO4 - Na2SO4

[0061] ⅰPreparation of polymer gel

[0062] 1) 0.5 g of polyacrylamide (molecular weight of 6-8 million), 0.4 g of phenol, 0.4 g of hexamethylenetetramine and 98.7 g of simulated mineralized water were weighed and mixed uniformly to obtain a polymer gel solution;

[0063] 2) 10 g of the polymer gel solution was injected into a thick-walled pressure-resistant screw neck bottle, and was aged at 110°C for 24 h to obtain a polymer gel;

[0064] According to the above method, 12 portions of polymer gels (10 g each) were prepared for standby.

[0065] ⅱUsing the plug removal composition to remove the plug of the polymer gel

[0066] 1) 10 g of the plug removal composition prepared in Examples 1-8 and Comparative Examples 1-4 was weighed and then added to the 12 portions of polymer gels prepared in i) (10 g of the plug removal composition was added to each portion of the polymer gel);

[0067] 2) The 12 groups of polymer gels to which the plug removal composition was added were placed in a constant temperature reaction at 110°C for 10 days, and during the reaction, observations were taken every 24 h; after the experiment, the residual mass of the polymer gel in each group was weighed;

[0068] The plug removal rate of the plug removal composition to the polymer gel was determined by the mass of the eroded polymer gel, and the calculation formula of the plug removal rate was formula (1):

[0069] K = (m0- m t ) / m0x 100% formula (1)

[0070] In the formula, K is the plug removal rate;

[0071] m t is the mass of the polymer gel after the reaction;

[0072] m0is the mass of the polymer gel before the reaction.

[0073] The plug removal rate data is shown in Table 1, and the plug removal situation at 24 h of the experiment is shown in Table 2. Figure 1

[0074] ​Table 1. Rate of polymer gel cleanup by cleanup composition at 110°C, 218100.55 mg / L salinity

[0075] Serial number 10 days plug breaking rate / % Example 1 95.66 Example 2 95.73 Example 3 87.33 Example 4 88.90 Example 5 96.53 Example 6 95.83 Example 7 98.32 Example 8 98.73 Comparative Example 1 47.52 Comparative Example 2 45.86 Comparative Example 3 73.21 Comparative Example 4 67.42

[0076] The data in Table 1 shows that the polymer gel plugging rate of the plugging composition prepared in Examples 1 to 8 is 87.33% to 98.73% when the temperature is 110°C and the salinity is 218100.55 mg / L, and the plugging effect is good; the polymer gel plugging rate of the plugging composition prepared in Comparative Examples 1 to 4 is 45.86% to 73.21%, and the plugging effect is poor. According to the data of the polymer gel plugging rate of Examples 1 and 2, when the concentration of the oxidant in the plugging composition reaches 6 wt%, the polymer gel plugging rate does not increase significantly with the further increase of the concentration of the oxidant. According to the data of the polymer gel plugging rate of Examples 1 and 5, and Examples 2 and 6, when the concentration of the oxidant in the plugging composition is 6 wt% to 12 wt% and the concentration of the activator is 0.3 wt%, the polymer gel plugging rate does not increase significantly with the further increase of the concentration of the stabilizer. According to the data of the polymer gel plugging rate of Examples 1 and 3, when the concentration of the oxidant in the plugging composition is 6 wt%, the concentration of the stabilizer is 0.5 wt%, and the concentration of the complexing agent is 3 wt%, the polymer gel plugging rate decreases with the further increase of the concentration of the activator. According to the data of the polymer gel plugging rate of Examples 7 and 3, and Examples 8 and 4, when the concentration of the oxidant in the plugging composition is 6 wt% to 12 wt%, the concentration of the activator is 0.6 wt%, and the concentration of the complexing agent is 3 wt%, the polymer gel plugging rate of the plugging composition increases significantly with the further increase of the concentration of the stabilizer. According to the data of the polymer gel plugging rate of Examples 3 and 8, when the concentration of the activator in the plugging composition is 0.6 wt% and the concentration of the complexing agent is 3 wt%, the polymer gel plugging rate of the plugging composition increases significantly with the further increase of the concentration of the oxidant and the stabilizer. According to the comparison of Examples 1 and 2 with Comparative Examples 1 and 2, the polymer gel plugging rate of the plugging composition without the stabilizer and the complexing agent decreases to less than 50%, which may be due to the rapid decomposition and consumption of the oxidant under the action of high temperature and the activator, and the precipitation of the oxidant and the activator under high temperature, which affects the plugging reaction and results in a poor plugging rate. According to the comparison of Example 1 with Comparative Examples 1 and 3, the polymer gel plugging rate of the plugging composition increases by about 25.69% with the addition of the stabilizer, which shows that the stabilizer improves the temperature resistance of the plugging composition and delays the decomposition rate of the oxidant, thereby improving the plugging rate of the plugging composition. On this basis, the solubility of the plugging composition is further improved with the addition of the complexing agent, and the plugging rate of the plugging composition further increases to 95.66%.The same comparative example 1, comparative example 1, comparative example 4 can also be found that the complexing agent is added to the plugging removal composition, the solubility is improved, and thus the plugging removal rate is increased by about 20%, on this basis, the stabilizer is added to improve the temperature resistance of the oxidizing agent, and the decomposition rate of the oxidizing agent is delayed, and thus the plugging removal rate is further increased by about 28%. It can be seen that the addition of the stabilizer and the complexing agent can effectively improve the plugging removal effect of the plugging removal composition, and the stabilizer, the complexing agent, the oxidizing agent and the activator synergistically improve the plugging removal effect of the plugging removal composition.

[0077] Figure 1 In the figure, from left to right, the dissolution of the plugging removal compositions prepared in example 1, example 3, example 2 and example 4 to the polymer gel under the condition of 110℃ and the salinity of 218100.55mg / L for 24h can be seen, Figure 1 In the figure, from left to right, the dissolution of the plugging removal compositions prepared in example 1, example 3, example 2 and example 4 to the polymer gel under the condition of 110℃ and the salinity of 218100.55mg / L for 24h can be seen,

[0078] The above analysis of table 1, Figure 1 It can be seen from the above analysis of table 1,

[0079] Although the present application has been described with reference to specific embodiments, it is understood by those skilled in the art that various changes can be made without departing from the true spirit and scope of the present application. In addition, various changes can be made to the subject matter, spirit and scope of the present application to adapt to specific circumstances, materials, material compositions and methods. All these changes are included in the scope of the claims of the present application.

Claims

1. A plug removal composition, comprising an oxidizing agent, an activator, a stabilizer, a complexing agent and a solvent; the oxidizing agent is a persulfate salt; the activator is sodium bisulfate; the stabilizer is sodium sulfamate and / or sodium carbonate; the complexing agent is selected from at least one of polyamino polyether based methylene phosphoric acid, hydroxy ethylene diphosphoric acid and 2-phosphonobutane-1, 2, 4-tricarboxylic acid; the plug removal composition comprises 6wt% to 12wt% of the oxidizing agent, 0.3wt% to 0.6wt% of the activator, 0.5wt% to 1wt% of the stabilizer, 3wt% of the complexing agent and the rest of the solvent, based on 100% of the mass of the plug removal composition.

2. The cleanup composition of claim 1, wherein, the solvent is water or mineralized water. 3.The plug removal composition according to claim 1 or 2 is applied in polymer gel plug removal.

4. Use according to claim 3, characterized in that, the application is the application of the plug removal composition as a polymer gel plug remover.

5. Use according to claim 3, characterized in that, the temperature of the application is not less than 110℃; and / or the salinity of the application ranges from 0 to 218000mg / L.

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