Low-viscosity temperature-resistant acid liquid retarder and preparation method thereof

Abstract

The application provides a low-viscosity temperature-resistant acid liquid retarder and a preparation method thereof. The low-viscosity temperature-resistant acid liquid retarder is a novel retarder polymerized by DMC, AM, DMDAAC, DMAAC-18 and perfluorooctyl acrylate. Experiments show that the low-viscosity temperature-resistant acid liquid retarder has multiple beneficial effects in the field of petrochemical industry. On the one hand, the addition of cationic surfactants such as DMDAAC and DMAAC-18 can form a barrier film on the rock surface to reduce the acid-rock reaction rate; on the other hand, the addition of perfluorooctyl acrylate can reduce the molecular weight of the polymer, so that the pollution to the formation is reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of petroleum chemical industry, and relates to a preparation method of a low-viscosity temperature-resistant thickening agent, in particular to a low-viscosity temperature-resistant acid liquid retarding agent and a preparation method thereof. BACKGROUND

[0002] In acidizing construction, the conventional acid liquid cannot communicate with the far well zone due to the fast acid-rock reaction speed, short effective action distance, and limited penetration depth, so that the stimulation effect is poor. In order to improve the acidizing effect, one of the most effective methods is to add a gelling agent to the acid liquid to control the diffusion speed of hydrogen ions, gradually dissolve the rock and its clay minerals, and enhance the penetration capacity of the acid liquid in the formation, so as to realize deep acidizing of the formation.

[0003] Among the acid liquid gelling agents tested at home and abroad, many guanidines, cellulose derivatives, high molecular biological polymers, and ethylene polymers are only suitable for conditions of well temperature lower than 70 DEG C and acid concentration lower than 20%, otherwise the thickening effect is poor, and the oil and gas layers are also damaged. With the increasing number of deep and ultra-deep wells, the conventional acid liquid system has limited retarding capacity and cannot form acid-etched cracks with a certain flow conductivity. With the deepening of oilfield development technology at home and abroad, higher requirements are put forward for the performance of the gelling agent. In order to improve the effectiveness of the acid liquid and expand the penetration range, especially to improve the productivity of low-permeability and high-temperature deep wells, it has become an inevitable trend to research a high-efficiency practical, low-cost and environmentally friendly gelling agent. The gelling agent system is an effective method for reducing the reaction speed of acid salts, and has a broad development prospect. In view of the current complex reservoir conditions, on the one hand, acrylamide polymers are used to effectively slow down the acid-rock reaction speed and increase the acid liquid action distance; on the other hand, new acidizing gelling agents are mainly researched to obtain a new gelling acid system for oilfield acidizing. The application synthesizes a new acrylamide polymer. SUMMARY

[0004] The application provides a low-viscosity temperature-resistant acid liquid retarding agent and a preparation method thereof, aiming at the poor temperature resistance and easy pollution of the existing thickening agent. The low-viscosity temperature-resistant acid liquid retarding agent has a wide raw material source, simple synthesis process, and low cost, and can effectively reduce the acid-rock reaction rate with a small amount. On the one hand, the addition of cationic surfactants such as DMDAAC and DMAAC-18 can form a barrier film on the rock surface to reduce the acid-rock reaction rate; on the other hand, the addition of perfluorooctyl acrylate can reduce the molecular weight of the polymer to reduce the pollution to the formation.

[0005] In order to achieve the above-mentioned application, the technical scheme adopted by the application is as follows:

[0006] A low-viscosity temperature-resistant acid liquid retarding agent has the following specific structural formula:

[0007]

[0008] The DMAAC-18 structure is as follows:

[0009]

[0010] The structural formula of perfluorooctyl ethyl acrylate is as follows:

[0011]

[0012] The specific preparation method of this low-viscosity, high-temperature resistant acid retarder includes the following steps:

[0013] Add DMC:AM:DMDAAC:DMAAC-18:perfluorooctyl acrylate in a mass ratio of 4-6:4-6:0.1-1:0.1-1:0.1-1 to a beaker sequentially. Add some deionized water, adjust the pH to 5-6 with acrylic acid and NaOH solution, then add more deionized water to achieve a solid content of 40-60%. After stirring and dissolving, add 0.06% (w / w) of initiator V50. Seal the container and purge with nitrogen for half an hour. Seal again and react in a 45°C water bath for 4-10 hours. Chop the resulting gel block, dry it at 50°C, and grind it into powder to obtain a low-viscosity, heat-resistant acid retarder.

[0014] Take a regular rectangular rock block, and calculate the ratio of the rock block's surface area to the hydrochloric acid's volume (1 cm³). 2 4cm 3 Prepare a 20% hydrochloric acid solution by adding 0.5% of the low-viscosity, high-temperature resistant gelling agent to the prepared 20% hydrochloric acid solution and stirring until homogeneous.

[0015] The dissolved solution was heated in a 90°C water bath for half an hour, and then rock blocks were placed in it. The rock blocks were then removed every 5 minutes to measure their mass and surface area until the 30th minute. A graph showing the change in the acid-rock reaction rate was plotted based on the data.

[0016] Furthermore, DMDAAC and DMAAC-18 in the steps can be other cationic surfactants.

[0017] Furthermore, in a preferred embodiment of the present invention, the pH in the step is 5.5-6, and the reaction time is 4-8 hours.

[0018] Furthermore, in a preferred embodiment of the present invention, the pH in the step is 5.8 and the reaction time is 6 hours.

[0019] Furthermore, in a preferred embodiment of the present invention, the above preparation method further includes a purification step: after synthesizing the rubber block, it is placed in acetone to fully dissolve for 4 hours, the acetone is poured out, and it is placed in a 50°C oven to dry for 4 hours. The purified low-viscosity, heat-resistant acid retarder is then obtained.

[0020] The present invention has the following beneficial effects:

[0021] (1) The preparation process of the low viscosity and temperature resistant acid retarder of the present invention is simple, the raw materials are easy to obtain, and all substances in the reaction process are products with no by-products.

[0022] (2) The low-viscosity, high-temperature resistant acid retarder of the present invention has excellent temperature resistance and its retarding ability meets the requirements of the field.

[0023] (3) The low viscosity and high temperature resistant acid retarder of the present invention has low viscosity, is easy to backflow, and has little damage to the formation. Attached Figure Description

[0024] Figure 1 Figure 1 shows the test results of acid dissolution time for low-viscosity, high-temperature resistant acid retarder.

[0025] Figure 2 Infrared spectral test results of low-viscosity, high-temperature resistant acid retarder.

[0026] Figure 3 Figure showing the reaction rate test results for a solid content of 40%.

[0027] Figure 4 The graph shows the reaction rate test results for a solid content of 45%.

[0028] Figure 5 The graph shows the reaction rate test results for a solid content of 50%.

[0029] Figure 6 The graph shows the reaction rate test results for a solid content of 55%.

[0030] Figure 7 The graph shows the reaction rate test results for a solid content of 60%. Detailed Implementation

[0031] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are for illustrative purposes only and are not intended to limit the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer should be followed. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0032] Example 1:

[0033] The preparation method of the low-viscosity, high-temperature resistant acid retarder in this embodiment includes:

[0034] The following ingredients were added sequentially to a beaker at a mass ratio of DMC:AM:DMDAAC:DMAAC-18:perfluorooctyl acrylate = 4:6:0.5:0.6:0.6: along with some deionized water. The pH was adjusted to 5.6 using acrylic acid and NaOH solution, followed by the addition of more deionized water to achieve a solid content of 40%. After stirring and dissolving, 0.06% (w / w) of initiator V50 was added. The mixture was sealed and purged with nitrogen for half an hour. After resealing, the mixture was reacted in a 45°C water bath for 4 hours. The resulting gel block was then chopped, dried at 50°C, and ground into powder to obtain a low-viscosity, heat-resistant acid retarder.

[0035] Take a regular rectangular rock block, and calculate the ratio of the rock block's surface area to the hydrochloric acid's volume (1 cm³). 2 4cm 3 Prepare a 20% hydrochloric acid solution by adding 0.5% of a low-viscosity, heat-resistant acid retarder to the prepared 20% hydrochloric acid solution and stirring until homogeneous.

[0036] The dissolved solution was heated in a 90℃ water bath for half an hour, and then rock blocks were placed in it. The rock blocks were then removed every 5 minutes to measure their mass and surface area until the 30th minute. A graph showing the acid-rock reaction rate was plotted based on the data. At the fifth minute, the acid-rock reaction rate was 11.872 g / (m³). 2 The concentration of 20% HCl solution decreased by 14.128 g / (m²) compared to the blank control group. 2 ·s).

[0037] Example 2:

[0038] The preparation method of the low-viscosity, high-temperature resistant acid retarder in this embodiment includes:

[0039] The following ingredients were added sequentially to a beaker at a mass ratio of DMC:AM:DMDAAC:DMAAC-18:perfluorooctyl acrylate = 5:4:0.3:0.6:0.8: along with some deionized water. The pH was adjusted to 5.7 using acrylic acid and NaOH solution, followed by the addition of more deionized water to achieve a solid content of 45%. After stirring and dissolving, 0.06% (w / w) of initiator V50 was added. The mixture was sealed and purged with nitrogen for half an hour. After resealing, the mixture was reacted in a 45°C water bath for 6 hours. The resulting gel block was chopped, dried at 50°C, and ground into powder to obtain a low-viscosity, heat-resistant acid retarder.

[0040] Take a regular rectangular rock block, and calculate the ratio of the rock block's surface area to the hydrochloric acid's volume (1 cm³). 2 4cm 3 Prepare a 20% hydrochloric acid solution by adding 0.5% of a low-viscosity, heat-resistant acid retarder to the prepared 20% hydrochloric acid solution and stirring until homogeneous.

[0041] The dissolved solution was heated in a 90℃ water bath for half an hour, and then rock blocks were placed in it. The rock blocks were then removed every 5 minutes to measure their mass and surface area until the 30th minute. A graph showing the acid-rock reaction rate was plotted based on the data. At the fifth minute, the acid-rock reaction rate was 11.297 g / (m³). 2 The concentration of 20% HCl solution decreased by 14.703 g / (m²) compared to the blank control group. 2 ·s).

[0042] Example 3:

[0043] The preparation method of the low-viscosity, high-temperature resistant acid retarder in this embodiment includes:

[0044] The following ingredients were added sequentially to a beaker at a mass ratio of DMC:AM:DMDAAC:DMAAC-18:perfluorooctyl acrylate = 6:4:1:1:1: , followed by the addition of some deionized water. The pH was adjusted to 5.8 using acrylic acid and NaOH solution, and then more deionized water was added to bring the solid content to 50%. After stirring and dissolving, 0.06% (w / w) of initiator V50 was added. The mixture was sealed and purged with nitrogen for half an hour. After resealing, the mixture was reacted in a 45°C water bath for 8 hours. The resulting gel block was chopped, dried at 50°C, and ground into powder to obtain a low-viscosity, heat-resistant acid retarder.

[0045] Take a regular rectangular rock block, and calculate the ratio of the rock block's surface area to the hydrochloric acid's volume (1 cm³). 2 4cm 3 Prepare a 20% hydrochloric acid solution by adding 0.5% of a low-viscosity, heat-resistant acid retarder to the prepared 20% hydrochloric acid solution and stirring until homogeneous.

[0046] The dissolved solution was heated in a 90℃ water bath for half an hour, and then rock blocks were placed in it. The rock blocks were then removed every 5 minutes to measure their mass and surface area until the 30th minute. A graph showing the acid-rock reaction rate was plotted based on the data. At the fifth minute, the acid-rock reaction rate was 8.858 g / (m³). 2 The concentration of 20% HCl solution decreased by 17.142 g / (m²) compared to the blank control group. 2 ·s).

[0047] Example 4:

[0048] The preparation method of the low-viscosity, high-temperature resistant acid retarder in this embodiment includes:

[0049] DMC:AM:DMDAAC:DMAAC-18:perfluorooctyl acrylate in a mass ratio of 4:4:0.7:0.7:0.3 was added sequentially to a beaker, followed by some deionized water. The pH was adjusted to 5.9 using acrylic acid and NaOH solution, and then more deionized water was added to achieve a solid content of 55%. After stirring and dissolving, 0.06% (w / w) of initiator V50 was added. The mixture was sealed and purged with nitrogen for half an hour, then sealed again and reacted in a 45°C water bath for 9 hours. The resulting gel block was chopped, dried at 50°C, and ground into powder to obtain a low-viscosity, heat-resistant acid retarder.

[0050] Take a regular rectangular rock block, and calculate the ratio of the rock block's surface area to the hydrochloric acid's volume (1 cm³). 2 4cm 3 Prepare a 20% hydrochloric acid solution by adding 0.5% of a low-viscosity, heat-resistant acid retarder to the prepared 20% hydrochloric acid solution and stirring until homogeneous.

[0051] The dissolved solution was heated in a 90℃ water bath for half an hour, and then rock blocks were placed in it. The rock blocks were then removed every 5 minutes to measure their mass and surface area until the 30th minute. A graph showing the acid-rock reaction rate was plotted based on the data. At the fifth minute, the acid-rock reaction rate was 9.326 g / (m³). 2 The concentration of 20% HCl solution decreased by 16.674 g / (m²) compared to the blank control group. 2 ·s).

[0052] Example 5:

[0053] The preparation method of the low-viscosity, high-temperature resistant acid retarder in this embodiment includes:

[0054] DMC:AM:DMDAAC:DMAAC-18:perfluorooctyl acrylate in a mass ratio of 6:6:0.8:0.8:0.4 was added sequentially to a beaker, followed by some deionized water. The pH was adjusted to 6 using acrylic acid and NaOH solution, and then more deionized water was added to achieve a solid content of 60%. After stirring and dissolving, 0.06% (w / w) of initiator V50 was added. The mixture was sealed and purged with nitrogen for half an hour. After resealing, the mixture was reacted in a 45°C water bath for 10 hours. The resulting gel block was chopped, dried at 50°C, and ground into powder to obtain a low-viscosity, heat-resistant acid retarder.

[0055] Take a regular rectangular rock block, and calculate the ratio of the rock block's surface area to the hydrochloric acid's volume (1 cm³). 2 4cm 3 Prepare a 20% hydrochloric acid solution by adding 0.5% of a low-viscosity, heat-resistant acid retarder to the prepared 20% hydrochloric acid solution and stirring until homogeneous.

[0056] The dissolved solution was heated in a 90℃ water bath for half an hour, and then rock blocks were placed in it. The rock blocks were then removed every 5 minutes to measure their mass and surface area until the 30th minute. A graph showing the acid-rock reaction rate was plotted based on the data. At the fifth minute, the acid-rock reaction rate was 10.112 g / (m²). 2 The concentration of 20% HCl solution decreased by 15.888 g / (m²) compared to the blank control group. 2 ·s).

Claims

1. A low-viscosity, high-temperature resistant acid retarder, characterized in that, A retarder polymerized from methacryloyloxyethyltrimethylammonium chloride, acrylamide, dimethyldiallylammonium chloride, octadecyldimethylallylammonium chloride, and perfluorooctyl acrylate, with a mass ratio of methacryloyloxyethyltrimethylammonium chloride:acrylamide:dimethyldiallylammonium chloride:octadecyldimethylallylammonium chloride:perfluorooctyl acrylate = 4~6:4~6:0.1~1:0.1~1:0.1~1.

2. The method for synthesizing the low-viscosity, high-temperature resistant acid retarder as described in claim 1, characterized in that, include: The following ingredients are added sequentially to a beaker in a mass ratio of methacryloyloxyethyltrimethylammonium chloride: acrylamide: dimethyl diallyl ammonium chloride: octadecyl dimethyl allyl ammonium chloride: perfluorooctyl acrylate = 4-6: 4-6: 0.1-1: 0.1-1: 0.1-1: 0.1-1. A portion of deionized water is added, and the pH is adjusted to 5-6 using acrylic acid and NaOH solution. More deionized water is added to achieve a solid content of 40-60%. After stirring and dissolving, 0.06% (w / w) of initiator V50 is added. The beaker is sealed and purged with nitrogen for half an hour. After resealing, the mixture is reacted in a 45°C water bath for 4-10 hours. The resulting gel block is chopped, dried at 50°C, and ground into powder to obtain a low-viscosity, heat-resistant acid retarder.

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