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

Abstract

The invention provides a low-viscosity temperature-resistant acid solution retarder and a preparation method thereof. The low-viscosity temperature-resistant acid solution retarder disclosed by the invention is a novel retarder which is formed by polymerizing DMC (Dimethyl Carbonate), AM (Acrylamide), DMDAAC (Dimethylaminoethyl Ammonium Chloride), DMAAC-18, perfluorooctyl acrylate and the like. Experiments show that the low-viscosity temperature-resistant acid solution retarder provided by the invention has multiple beneficial effects in the field of petrochemical engineering, on one hand, cationic surfactants such as DMDAAC and DMAAC-18 are added, so that a barrier film can be formed on the surface of rock, and the acid rock reaction rate is reduced; on the other hand, the addition of perfluorooctyl acrylate can reduce the molecular weight of the polymer, so that the pollution to the stratum is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of petrochemical industry and relates to a method for preparing a low-viscosity and temperature-resistant thickener, in particular to a low-viscosity and temperature-resistant acid liquid retarder and a method for preparing the same. Background Art

[0002] Conventional acid fluid cannot reach the far well area due to the fast acid-rock reaction speed, short effective action distance and limited penetration depth in acidizing construction, so the production increase measures are less effective. In order to improve the acidizing effect, one of the most effective methods is to add gelling agent to the acid fluid to control the diffusion rate of hydrogen ions, gradually dissolve the rock and its clay minerals, enhance the penetration ability of the acid fluid in the formation, and thus achieve deep acidizing of the formation.

[0003] Among the acid gelling agents tested at home and abroad, many guar gums, cellulose derivatives, high molecular biopolymers, and ethylene polymers are only suitable for conditions where the well temperature is lower than 70°C and the acid concentration is lower than 20% due to the limitation of their molecular structure. Otherwise, the thickening effect will be poor and the oil and gas layers will be damaged. Deep wells and ultra-deep wells are increasing day by day. The conventional acid system has limited retarding capacity and cannot form longer acid-etched fractures with certain conductivity. With the deepening of oil field development technology at home and abroad, higher requirements are also put forward for the performance of gelling agents. In order to improve the effectiveness of acid and expand the penetration range, especially to improve the production capacity of low permeability and high temperature deep wells, it has become an inevitable trend to develop a highly efficient, practical, low-cost and environmentally friendly gelling agent. As an effective method to reduce the reaction rate of acid salts, the gelling agent system has a relatively broad development prospect. In view of the current complex reservoir conditions, on the one hand, the use of acrylamide polymers can effectively slow down the acid-rock reaction rate and increase the acid action distance; on the other hand, the main research is on new acidizing gelling agents to obtain new oil field acidizing gelling acid systems. The present invention synthesizes a new type of acrylamide polymer. Summary of the invention

[0004] The present invention provides a low-viscosity, heat-resistant acid liquid retarder and a preparation method thereof to address the shortcomings of existing thickeners, such as poor heat resistance and easy pollution. The low-viscosity, heat-resistant acid liquid retarder has a wide range of raw materials, a 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 and reduce the acid-rock reaction rate; on the other hand, the addition of perfluorooctyl acrylate can reduce the molecular weight of the polymer, thereby reducing pollution to the formation.

[0005] In order to realize the above invention, the technical solution adopted by the present invention is as follows:

[0006] A low-viscosity, temperature-resistant acid liquid retarder, the specific structural formula of which is as follows:

[0007]

[0008] The structural formula of DMAAC-18 is as follows:

[0009] The structural formula of perfluorooctyl ethyl acrylate is as follows:

[0010] The specific preparation method of the low-viscosity temperature-resistant acid liquid retarder comprises the following steps:

[0011] According to the mass ratio of DMC:AM:DMDAAC:DMAAC-18:perfluorooctyl acrylate = 4-6:4-6:0.1-1:0.1-1:0.1-1, add them into a beaker in sequence, add some deionized water, adjust the pH to 5-6 with acrylic acid and NaOH solution, and then add deionized water to make the solid content 40-60%. After stirring and dissolving, add 0.06% of initiator V50. After sealing, pass nitrogen for half an hour, seal again and react under 45℃ water bath heating conditions for 4-10 hours, chop the obtained rubber block, dry and grind it into powder at 50℃ to obtain a low-viscosity temperature-resistant acid retarder. Take a regular rectangular block of rock, with the surface area of ​​the rock: the volume of hydrochloric acid = 1cm 2 :4cm 3 Prepare a 20% hydrochloric acid solution with an amount of, dissolve 0.5% of the low-viscosity temperature-resistant gelling agent in the 20% hydrochloric acid solution prepared above, and stir evenly. Heat the dissolved solution in a 90℃ water bath for half an hour and then put the rock in. Then take out the rock every 5 minutes and measure its mass and surface area until the 30th minute. Draw a graph of the acid-rock reaction rate based on the data.

[0012] Furthermore, the DMDAAC and DMAAC-18 in the step may be other cationic surfactants.

[0013] 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.

[0014] Furthermore, in a preferred embodiment of the present invention, the pH in the step is 5.8 and the reaction time is 6 hours.

[0015] Furthermore, in a preferred embodiment of the present invention, the above preparation method also includes a purification step: after the synthetic rubber block, put it into acetone to fully dissolve it for 4 hours, pour out the acetone, put it into a 50°C oven and bake it for 4 hours, and take it out to obtain the purified low-viscosity temperature-resistant acid liquid retarder.

[0016] The present invention has the following beneficial effects:

[0017] (1) The preparation process of the low-viscosity temperature-resistant acid liquid retarder of the present invention is simple, the raw materials are easy to obtain, and the substances in the reaction process are all products without any by-products;

[0018] (2) The low-viscosity, temperature-resistant acid liquid retarder of the present invention has good temperature resistance, and its retarding capacity meets the on-site requirements.

[0019] (3) The low-viscosity, temperature-resistant acid liquid retarder of the present invention has low viscosity, is easy to flow back, and has little damage to the formation. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The test results of acid dissolution time of low viscosity and temperature resistant acid retarder

[0021] Figure 2 This is the infrared spectrum test result of low viscosity and temperature resistant acid liquid retarder

[0022] Figure 3 Reaction rate test results for solid content 40%

[0023] Figure 4 Reaction rate test results for solid content 45%

[0024] Figure 5 Reaction rate test results for solid content 50%

[0025] Figure 6 Reaction rate test results for solid content 55%

[0026] Figure 7 Reaction rate test results for solid content 60% DETAILED DESCRIPTION

[0027] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples are only used to explain the present invention and are not used to limit the scope of the present invention. If specific conditions are not specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0028] Embodiment 1:

[0029] The preparation method of the low-viscosity temperature-resistant acid liquid retarder of the present embodiment comprises:

[0030] According to the mass ratio of DMC:AM:DMDAAC:DMAAC-18:perfluorooctyl acrylate = 4:6:0.5:0.6:0.6, add them to the beaker in turn, add some deionized water, adjust the pH to 5.6 with acrylic acid and NaOH solution, and then add deionized water to make the solid content 40%. After stirring and dissolving, add 0.06% of the initiator V50. After sealing, pass nitrogen for half an hour, seal again and react under 45℃ water bath heating conditions for 4h, chop the obtained rubber block, dry and grind it into powder at 50℃ to obtain a low-viscosity temperature-resistant acid retarder. Take a regular rectangular block of rock, with the surface area of ​​the rock: the volume of hydrochloric acid = 1cm 2 :4cm 3 Prepare a 20% hydrochloric acid solution with the amount of, dissolve 0.5% low-viscosity temperature-resistant acid liquid retarder into the prepared 20% hydrochloric acid solution, and stir evenly. Heat the dissolved solution in a 90℃ water bath for half an hour and then put the rock in. Then take out the rock every 5 minutes and measure its mass and surface area until the 30th minute. Draw a graph of the acid-rock reaction rate based on the data. At the fifth minute, the acid-rock reaction rate is 11.872 g / (m 2 ·s), and compared with the blank group of 20% HCl solution, it decreased by 14.128g / (m 2 ·s).

[0031] Embodiment 2:

[0032] The preparation method of the low-viscosity temperature-resistant acid liquid retarder of the present embodiment comprises:

[0033] According to the mass ratio of DMC:AM:DMDAAC:DMAAC-18:perfluorooctyl acrylate = 5:4:0.3:0.6:0.8, add them into a beaker in sequence, add some deionized water, adjust the pH to 5.7 with acrylic acid and NaOH solution, and then add deionized water to make the solid content 45%. After stirring and dissolving, add 0.06% of initiator V50. After sealing, pass nitrogen for half an hour, seal again and react under 45℃ water bath heating conditions for 6 hours, chop the obtained rubber block, dry and grind it into powder at 50℃, and obtain a low-viscosity temperature-resistant acid retarder. Take a regular rectangular block of rock, with the surface area of ​​the rock: the volume of hydrochloric acid = 1cm 2 :4cm 3 Prepare a 20% hydrochloric acid solution with the amount of, dissolve 0.5% low-viscosity temperature-resistant acid liquid retarder into the prepared 20% hydrochloric acid solution, and stir evenly. Heat the dissolved solution in a 90℃ water bath for half an hour and then put the rock in. Then take out the rock every 5 minutes and measure its mass and surface area until the 30th minute. Draw a graph of the acid-rock reaction rate based on the data. At the fifth minute, the acid-rock reaction rate is 11.297 g / (m 2 ·s), and compared with the blank group of 20% HCl solution, it decreased by 14.703g / (m 2 ·s).

[0034] Embodiment 3:

[0035] The preparation method of the low-viscosity temperature-resistant acid liquid retarder of the present embodiment comprises:

[0036] According to the mass ratio of DMC:AM:DMDAAC:DMAAC-18:perfluorooctyl acrylate = 6:4:1:1:1, add them into a beaker in turn, add some deionized water, adjust the pH to 5.8 with acrylic acid and NaOH solution, and then add deionized water to make the solid content 50%. After stirring and dissolving, add 0.06% of initiator V50. After sealing, pass nitrogen for half an hour, seal again and react under 45℃ water bath heating conditions for 8h, chop the obtained rubber block, dry and grind it into powder at 50℃ to obtain a low-viscosity temperature-resistant acid retarder. Take a regular rectangular block of rock, with the surface area of ​​the rock: the volume of hydrochloric acid = 1cm 2 :4cm 3 Prepare a 20% hydrochloric acid solution with the amount of, dissolve 0.5% low-viscosity temperature-resistant acid liquid retarder into the prepared 20% hydrochloric acid solution, and stir evenly. Heat the dissolved solution in a 90℃ water bath for half an hour and then put the rock in. Then take out the rock every 5 minutes and measure its mass and surface area until the 30th minute. Draw a graph of the acid-rock reaction rate based on the data. At the fifth minute, the acid-rock reaction rate is 8.858 g / (m 2 ·s), and compared with the blank group of 20% HCl solution, it decreased by 17.142g / (m 2 ·s).

[0037] Embodiment 4:

[0038] The preparation method of the low-viscosity temperature-resistant acid liquid retarder of the present embodiment comprises:

[0039] According to the mass ratio of DMC:AM:DMDAAC:DMAAC-18:perfluorooctyl acrylate = 4:4:0.7:0.7:0.3, add them into a beaker in sequence, add some deionized water, adjust the pH to 5.9 with acrylic acid and NaOH solution, and then add deionized water to make the solid content 55%. After stirring and dissolving, add 0.06% of initiator V50. After sealing, pass nitrogen for half an hour, seal again and react under 45℃ water bath heating conditions for 9 hours, chop the obtained rubber block, dry and grind it into powder at 50℃ to obtain a low-viscosity temperature-resistant acid retarder. Take a regular rectangular block of rock, with the surface area of ​​the rock: the volume of hydrochloric acid = 1cm 2 :4cm 3 Prepare a 20% hydrochloric acid solution with the amount of, dissolve 0.5% low-viscosity temperature-resistant acid liquid retarder into the prepared 20% hydrochloric acid solution, and stir evenly. Heat the dissolved solution in a 90℃ water bath for half an hour and then put the rock in. Then take out the rock every 5 minutes and measure its mass and surface area until the 30th minute. Draw a graph of the acid-rock reaction rate based on the data. At the fifth minute, the acid-rock reaction rate is 9.326 g / (m 2 ·s), and compared with the blank group of 20% HCl solution, it decreased by 16.674g / (m 2 ·s).

[0040] Embodiment 5:

[0041] The preparation method of the low-viscosity temperature-resistant acid liquid retarder of the present embodiment comprises:

[0042] According to the mass ratio of DMC:AM:DMDAAC:DMAAC-18:perfluorooctyl acrylate = 6:6:0.8:0.8:0.4, add them into a beaker in sequence, add some deionized water, adjust the pH to 6 with acrylic acid and NaOH solution, and then add deionized water to make the solid content 60%. After stirring and dissolving, add 0.06% of initiator V50. After sealing, pass nitrogen for half an hour, seal again and react under 45℃ water bath heating conditions for 10 hours, chop the obtained rubber block, dry and grind it into powder at 50℃, and obtain a low-viscosity temperature-resistant acid retarder. Take a regular rectangular block of rock, with the surface area of ​​the rock: the volume of hydrochloric acid = 1cm 2 :4cm 3 Prepare a 20% hydrochloric acid solution with the amount of, dissolve 0.5% low-viscosity temperature-resistant acid liquid retarder into the prepared 20% hydrochloric acid solution, and stir evenly. Heat the dissolved solution in a 90℃ water bath for half an hour and then put the rock in. Then take out the rock every 5 minutes and measure its mass and surface area until the 30th minute. Draw a graph of the acid-rock reaction rate based on the data. At the fifth minute, the acid-rock reaction rate is 10.112 g / (m 2 ·s), and compared with the blank group of 20% HCl solution, it decreased by 15.888g / (m 2 ·s).

Claims

1. A low-viscosity, temperature-resistant acid liquid retarder and a preparation method thereof, characterized in that: By DMC, AM, A new type of retarder synthesized from DMDAAC, DMAAC-18 and perfluorooctyl acrylate.

2. As described in claim 1, the low-viscosity temperature-resistant acid liquid retarder is polymerized from DMC, AM, DMDAAC, DMAAC-18, and perfluorooctyl acrylate.

3. As claimed in claim 2, a method for synthesizing a low-viscosity temperature-resistant acid liquid retarder, characterized in that: include: (1) Add the mass ratio of DMC:AM:DMDAAC:DMAAC-18:perfluorooctyl acrylate to a beaker in sequence, add some deionized water, adjust the pH to 5-6 with acrylic acid and NaOH solution, and then add deionized water to make the solid content 40-60%. After stirring and dissolving, add 0.06% of initiator V50. After sealing, introduce nitrogen for half an hour, seal again, and react in a 45°C water bath for 4-10 hours. Cut the obtained rubber block into pieces, dry and grind it into powder at 50°C to obtain a low-viscosity temperature-resistant acid retarder. (2) Take a regular rectangular block of rock and calculate the surface area of ​​the rock: volume of hydrochloric acid = 1 cm 2 :4cm 3 Prepare a 20% hydrochloric acid solution with the amount of, dissolve 0.5% low-viscosity temperature-resistant acid liquid retarder into the prepared 20% hydrochloric acid solution, and stir evenly. (3) Heat the dissolved solution in a 90°C water bath for half an hour and then add the rock. Take out the rock every 5 minutes and measure its mass and surface area until the 30th minute. Draw a graph of the acid-rock reaction rate based on the data.

4. As described in claim 3, DMDAAC and DMAAC-18 in the preparation of the low-viscosity temperature-resistant acid liquid retarder can be other cationic monomers.

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