Self-diverting gelled acid for sandstone formation acidification transformation

Abstract

The invention relates to the technical field of sandstone formation acidification diverting, in particular to self-diverting gelled acid for sandstone formation acidification transformation. Comprising the following preparation processes: (1) at room temperature, sequentially adding 89.88-93.88 parts by weight of distilled water and 0.12 part by weight of cationic polyacrylamide into a reaction kettle, and stirring for 3 minutes at the rotating speed of 2000; (2) sequentially adding 6.0-10 parts by weight of betaine, and stirring for 3 minutes at the rotating speed of 2000; and (3) transferring the prepared liquid into a centrifuge tube, and then centrifuging for 10 minutes under the condition of 3000 revolutions per minute to remove bubbles in the liquid. The beneficial effects comprise that the drilling fluid is suitable for various sandstone well conditions and stratums, is especially suitable for stratums with high water content and permeability, improves oil and gas yield by reducing water yield and effectively turning, and significantly enhances the viscosity effect of betaine due to the addition of 0.12% of cationic polyacrylamide.

Description

Technical Field

[0001] The invention relates to the technical field of acidification diversion of sandstone formations, in particular to a self-diverting gelled acid for acidification transformation of sandstone formations. Background Art

[0002] In oilfield exploitation, especially in acidizing and production enhancement operations in complex sandstone formations, diverting acid to the target layer is an important factor in increasing oil production. Gel diverters mainly rely on high viscosity to block water channeling channels. Their penetration into the formation is limited, and they are mostly suitable for blocking water channeling channels in cracks near the wellbore and high permeability layers. Moreover, existing gel diverters generally contain high-risk acids such as hydrofluoric acid and hydrochloric acid, and there are many types of additives, which have high production costs. In addition, they are not suitable for high-temperature formations above 150°C. In addition, they are not effective in formations with high water content and permeability. Summary of the invention

[0003] The purpose of the present invention is to provide a self-diverting gelled acid for acidizing and reforming sandstone formations in view of the above-mentioned defects in the prior art. The gelled acid is suitable for a variety of sandstone well conditions and formations, and is particularly suitable for formations with high water content and permeability. It increases oil and gas production by reducing water production and effectively diverting water. The addition of 0.12% cationic polyacrylamide significantly enhances the viscosity effect of betaine.

[0004] The present invention discloses a self-steering gelled acid for acidizing and reforming sandstone formations, and the technical scheme thereof comprises the following preparation process: (1) At room temperature, 89.88-93.88 parts by weight of distilled water and 0.12 parts by weight of cationic polyacrylamide were added to a reaction kettle in sequence, and stirred at 2000 rpm for 3 minutes; (2) Add 6.0-10 parts by weight of betaine in sequence and stir at 2000 rpm for 3 minutes; (3) Transfer the prepared liquid to a centrifuge tube and then centrifuge at 3000 rpm for 10 minutes to remove bubbles in the liquid.

[0005] Preferably, the ratio of the above-mentioned betaine to the polymer is 6-10:0.12.

[0006] Preferably, the betaine is erucamidopropyl betaine or erucamidopropyl hydroxysulfobetaine.

[0007] Compared with the prior art, the beneficial effects of the present invention are as follows: 1) The applicable temperature of the present invention can reach 150°C; 2) No high-risk acids such as hydrofluoric acid and hydrochloric acid; 3) Applicable to formations with high water content and permeability; 4) Different rheological properties are shown in oil and water. The present invention automatically breaks gel when encountering oil or pretreatment fluid in the reservoir, but forms a higher micelle viscosity in the water-containing reservoir, thereby blocking the water-containing reservoir and allowing the subsequent main acidizing fluid to enter the oil-containing reservoir, thereby playing a diversion role; 5) Few types of additives; 6) The present invention uses 0.12% cationic polyacrylamide to significantly enhance the viscosity of erucamidopropyl betaine or erucamidopropyl hydroxysulfobetaine. The enhancement efficiency can reach 30% to 380% at different temperatures and different betaine addition amounts. 7) High economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a synergistic curve of the viscosity of 0.12% cationic polyacrylamide in 6% erucic acid amide propyl betaine solution changing with temperature; Figure 2 It is a synergistic curve of the viscosity of 0.12% cationic polyacrylamide in 10% erucic acid amide propyl betaine solution changing with temperature; Figure 3 It is a synergistic curve of the viscosity change of 0.12% cationic polyacrylamide in 7.5% erucamidopropyl hydroxysulfobetaine solution with temperature; Figure 4 It is a synergistic curve of the viscosity change of 0.12% cationic polyacrylamide in 10% erucamidopropyl hydroxysulfobetaine with temperature. DETAILED DESCRIPTION

[0009] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0010] Example 1: A self-steering gelled acid for acidizing sandstone formations mentioned in the present invention is prepared by the following steps: (1) At room temperature, 93.88 parts by weight of distilled water and 0.12 parts by weight of cationic polyacrylamide were added to a reaction kettle in sequence, and stirred at 2000 rpm for 3 minutes; (2) adding 6 parts by weight of erucamidopropyl betaine in sequence and stirring at 2000 rpm for 3 minutes; (3) Transfer the prepared liquid to a centrifuge tube and then centrifuge at 3000 rpm for 10 minutes to remove bubbles in the liquid.

[0011] Comparative experiment 1-1: (1) At room temperature, 99.88 parts by weight of distilled water and 0.12 parts by weight of cationic polyacrylamide were added to a reaction kettle in sequence, and stirred at 2000 rpm for 3 minutes; (2) Transfer the prepared liquid to a centrifuge tube and then centrifuge at 3000 rpm for 10 minutes to remove bubbles in the liquid.

[0012] Comparative experiment 1-2: (1) At room temperature, 94 parts by weight of distilled water and 6 parts by weight of erucamidopropyl betaine were added to a reaction kettle in sequence, and stirred at 2000 rpm for 3 minutes; (2) Transfer the prepared liquid to a centrifuge tube and then centrifuge at 3000 rpm for 10 minutes to remove bubbles in the liquid.

[0013] Example 2: A self-steering gelled acid for acidizing sandstone formations mentioned in the present invention is prepared by the following steps: (1) At room temperature, 89.88 parts by weight of distilled water and 0.12 parts by weight of cationic polyacrylamide were added to a reaction kettle in sequence, and stirred at 2000 rpm for 3 minutes; (2) adding 10 parts by weight of erucamidopropyl betaine in sequence and stirring at 2000 rpm for 3 minutes; (3) Transfer the prepared liquid to a centrifuge tube and then centrifuge at 3000 rpm for 10 minutes to remove bubbles in the liquid.

[0014] Comparative experiment 2-1: (1) At room temperature, 99.88 parts by weight of distilled water and 0.12 parts by weight of cationic polyacrylamide were added to a reaction kettle in sequence, and stirred at 2000 rpm for 3 minutes; (2) Transfer the prepared liquid to a centrifuge tube and then centrifuge at 3000 rpm for 10 minutes to remove bubbles in the liquid.

[0015] Comparative experiment 2-2: (1) At room temperature, 90 parts by weight of distilled water and 10 parts by weight of erucamidopropyl betaine were added to a reaction kettle in sequence, and stirred at 2000 rpm for 3 minutes; (2) Transfer the prepared liquid to a centrifuge tube and then centrifuge at 3000 rpm for 10 minutes to remove bubbles in the liquid.

[0016] Example 3: A self-steering gelled acid for acidizing sandstone formations mentioned in the present invention is prepared by the following steps: (1) At room temperature, 92.38 parts by weight of distilled water and 0.12 parts by weight of cationic polyacrylamide were added to a reaction kettle in sequence, and stirred at 2000 rpm for 3 minutes; (2) adding 7.5 parts by weight of erucamidopropyl hydroxysulfobetaine in turn, and stirring at 2000 rpm for 3 minutes; (3) Transfer the prepared liquid to a centrifuge tube and then centrifuge at 3000 rpm for 10 minutes to remove bubbles in the liquid.

[0017] Comparative experiment 3-1: (1) At room temperature, 99.88 parts by weight of distilled water and 0.12 parts by weight of erucamidopropyl hydroxysulfobetaine were added to a reaction kettle in sequence, and stirred at 2000 rpm for 3 minutes; (2) Transfer the prepared liquid to a centrifuge tube and then centrifuge at 3000 rpm for 10 minutes to remove bubbles in the liquid.

[0018] Comparative experiment 3-2: (1) At room temperature, 92.5 parts by weight of distilled water and 7.5 parts by weight of erucamidopropyl hydroxysulfobetaine were added to a reaction kettle in sequence, and stirred at 2000 rpm for 3 minutes; (2) Transfer the prepared liquid to a centrifuge tube and then centrifuge at 3000 rpm for 10 minutes to remove bubbles in the liquid.

[0019] Example 4: A self-steering gelled acid for acidizing sandstone formations mentioned in the present invention is prepared by the following steps: (1) At room temperature, 89.88 parts by weight of distilled water and 0.12 parts by weight of cationic polyacrylamide were added to a reaction kettle in sequence, and stirred at 2000 rpm for 3 minutes; (2) adding 10 parts by weight of erucamidopropyl hydroxysulfobetaine in sequence and stirring at 2000 rpm for 3 minutes; (3) Transfer the prepared liquid to a centrifuge tube and then centrifuge at 3000 rpm for 10 minutes to remove bubbles in the liquid.

[0020] Comparative experiment 4-1: (1) At room temperature, 99.88 parts by weight of distilled water and 0.12 parts by weight of cationic polyacrylamide were added to a reaction kettle in sequence, and stirred at 2000 rpm for 3 minutes; (2) Transfer the prepared liquid to a centrifuge tube and then centrifuge at 3000 rpm for 10 minutes to remove bubbles in the liquid.

[0021] Comparative experiment 4-2: (1) At room temperature, 90 parts by weight of distilled water and 10 parts by weight of erucamidopropyl hydroxysulfobetaine were added to a reaction kettle in sequence, and stirred at 2000 rpm for 3 minutes; (2) Transfer the prepared liquid to a centrifuge tube and then centrifuge at 3000 rpm for 10 minutes to remove bubbles in the liquid.

[0022] A Chandler 5550 high-temperature and high-pressure rheometer (AMETEK, USA) was used to measure the -1 The viscosity at high temperature and high pressure in the range of 100°F-300°F was measured at a shear rate and a pressure of 2.8 MPa, and the viscosity increase efficiency generated by adding 0.12% cationic polyacrylamide to the betaine system was calculated. Viscosity increase efficiency = (viscosity of betaine and polymer in water when acting together - viscosity of betaine in water - viscosity of polymer in water) / viscosity of betaine in water. The viscosity generated by the gelled acid of the present invention can meet the requirements of effective diversion of sandstone formations.

[0023] The performance test of a self-steering gelled acid for acidizing sandstone formations mentioned in the present invention is as follows: 1) Application of 0.12% cationic polyacrylamide in 6% erucic acid amide propyl betaine: The viscosity properties of the samples prepared in Example 1 and Comparative Experiments 1-1 and 1-2 are shown in Tables 1 and Figure 1 As shown, experimental data show that when the temperature is between 100°F and 237.5°F-275°F, adding a small amount of 0.12% cationic polyacrylamide can increase the viscosity of 6% erucic acid amidopropyl betaine by 30-70%.

[0024] 2) Application of 0.12% cationic polyacrylamide in 10% erucic acid amide propyl betaine: The viscosity properties of the samples prepared in Example 2 and Comparative Experiments 2-1 and 2-2 are shown in Tables 2 and Figure 2 As shown, experimental data show that when the temperature is between 100°F and 212.5°F-275°F, adding a small amount of 0.12% cationic polyacrylamide can increase the viscosity of 10% erucamidopropyl betaine by 30-60%.

[0025] 3) Application of 0.12% cationic polyacrylamide in 7.5% erucic acid amide propyl hydroxysulfobetaine: The viscosity properties of the samples prepared in Example 3 and Comparative Experiments 3-1 and 3-2 are shown in Tables 3 and Figure 3 As shown, experimental data show that when the temperature is between 250°F and 300°F, adding a small amount of 0.12% cationic polyacrylamide can increase the viscosity of 7.5% erucic acid amide propyl betaine by 50-380%.

[0026] 4) Application of 0.12% cationic polyacrylamide in 10% erucic acid amide propyl hydroxysulfobetaine: The viscosity properties of the samples prepared in Example 4 and Comparative Experiments 4-1 and 4-2 are shown in Tables 4 and Figure 4As shown, experimental data show that when the temperature is between 250°F and 300°F, adding a small amount of 0.12% cationic polyacrylamide can increase the viscosity of 10% erucamidopropyl hydroxysulfobetaine by 45-225%.

[0027] Table 1 Performance evaluation experimental data of samples prepared in Example 1 and comparative experiments 1-1 and 1-2

[0028] Table 2 Performance evaluation experimental data of samples prepared in Example 2 and comparative experiments 2-1 and 2-2

[0029] Table 3 Performance evaluation experimental data of samples prepared in Example 3 and comparative experiments 3-1 and 3-2

[0030] Table 4 Performance evaluation experimental data of samples prepared in Example 4 and comparative experiments 4-1 and 4-2

[0031] Through Tables 1 to 4 and Figures 1 to 4 From the performance evaluation data, it can be seen that adding a small amount of 0.12% cationic polyacrylamide has a significant viscosity enhancement effect on 6-10% erucamidopropyl betaine or 7.5-10% erucamidopropyl hydroxysulfonyl betaine, and the enhancement efficiency can reach 30-380%. This proves that cationic polyacrylamide can be used as a synergist and used in combination with the main agent betaine to form a new self-steering gelling acid system that meets the viscosity requirements. Although the amount of 0.12% cationic polyacrylamide added is small and the cost is low, its viscosity enhancement effect is very obvious and it has a high economic value.

[0032] The self-diverting gelled acid for acidizing and reforming sandstone formations mentioned in the present invention greatly improves the viscosity of the diverting acid system at high temperatures, especially when the temperature is between 200°F and 300°F.

[0033] The self-diverting gelled acid for acidizing and reforming sandstone formations mentioned in the present invention is used for sandstone production enhancement and reforming. It not only plays a diverting role so that the acid can be evenly distributed in each reformed layer, but also has the function of improving relative permeability, thereby increasing oil and gas production while reducing water output. The simple construction procedure and non-harmful characteristics of the present invention reduce the operation risk, improve the return of the treatment fluid, and improve the acidizing treatment effect.

[0034] The above are only some preferred embodiments of the present invention. Any person skilled in the art may modify the above technical solutions or modify them into equivalent technical solutions. Therefore, the corresponding simple modifications or equivalent transformations made according to the technical solutions of the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A self-diverting gelled acid for acidizing sandstone formations, characterized by: Includes the following Preparation process: (1) At room temperature, 89.88-93.88 parts by weight of distilled water and 0.12 parts by weight of cationic polyacrylamide were added to a reaction kettle in sequence, and stirred at 2000 rpm for 3 minutes; (2) Add 6.0-10 parts by weight of betaine in sequence and stir at 2000 rpm for 3 minutes; (3) Transfer the prepared liquid to a centrifuge tube and then centrifuge at 3000 rpm for 10 minutes to remove bubbles in the liquid.

2. The self-diverting gelled acid for acidizing sandstone formations according to claim 1 is characterized by: The ratio of betaine to polymer is 6-10:0.

12.

3. The self-diverting gelled acid for acidizing sandstone formations according to claim 2 is characterized by: The betaine is erucamidopropyl betaine or erucamidopropyl hydroxysulfobetaine.

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