A well bottom treatment agent, its preparation method and application

Abstract

The application provides a well bottom treatment agent, a preparation method and application thereof. The well bottom treatment agent comprises alcohol, a scale remover, a solubilizer, a wetting agent, a demulsifier and water.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of oilfield well bottom treatment, in particular to a well bottom treatment agent. BACKGROUND

[0002] The tight gas reservoir has the characteristics of low porosity, low permeability, strong heterogeneity and high capillary force.

[0003] In the production process, wellbore fluid accumulation often occurs, which produces water lock damage. Core experiment, numerical simulation and production dynamic analysis show that the skin factor of the gas well decreases first and then increases during the production process. The turning point is the beginning of wellbore fluid accumulation. The reverse osmosis water lock damage occurs, and the gas well production begins to decrease. The invasion depth of the reverse osmosis water lock damage is relatively shallow, generally within 10 cm, which needs to be removed by chemical method.

[0004] During the maintenance of most gas wells, foam drainage gas recovery is used. The long-term use of foam drainage agent causes the change of the physical characteristics of the discharged liquid. The discharged liquid becomes milky white and has viscosity. The gas well is difficult to carry. The long-term accumulation affects the productivity of the gas well, increases the seepage resistance of the gas well, and even completely blocks the gas well in severe cases.

[0005] The formation water of the gas field has the water chemical characteristics under the condition of long-term high sealing. The formation water has high salinity. The water type is mainly CaCl2 and Na2SO4 type, and is rich in a large amount of scale forming ions (Ca 2+ , Mg 2+ , CO3 2- , SO4 2- , HCO3 - ). When the environmental pressure and temperature change, the potential factors for producing carbonate and sulfate scale are provided, and the pores are blocked. The comprehensive factors affect the decrease of the gas well production and the abnormal decrease of the pressure, which seriously affects the stable production of the low-pressure and low-yield well.

[0006] At present, there is no multifunctional well bottom purification treatment agent with the functions of water lock removal, demulsification and scale dissolution and scale inhibition in China. The well bottom pollution treatment ability is single, the well bottom purification effect is not obvious, and the expected production recovery target cannot be achieved. SUMMARY

[0007] The present application provides a well bottom treatment agent, which comprises alcohol, scale removal agent, solubilizing agent, wetting agent, demulsifier and water.

[0008] In one specific embodiment, the content of the alcohol is 0.7% to 1.2%, the content of the scale removal agent is 8% to 10%, the content of the solubilizing agent is 2.4% to 3%, the content of the wetting agent is 0.1% to 1%, the content of the demulsifier is 5% to 6%, and the balance is water, based on 100% of the total mass of the well bottom treatment agent.

[0009] In one specific embodiment, the alcohol is at least two of ethanol, propanol, isopropanol, n-butanol, isooctanol, and dodecanol.

[0010] In one specific embodiment, the scale remover is at least one of disodium ethylenediaminetetraacetate, N-(2-hydroxyethyl)iminodiacetic acid, tetrasodium aminotri(methylene phosphonate), and sodium diethylenetriaminepentaacetate.

[0011] In one specific embodiment, the solubilizing agent is at least one of potassium chloride, potassium formate, and sodium formate.

[0012] In one specific embodiment, the wetting agent is at least one of octadecyltrimethylammonium chloride, polyetheramine D230, and cetyltrimethylammonium chloride.

[0013] In one specific embodiment, the demulsifier is a polyether demulsifier; preferably, the demulsifier is at least one of SP-type polyoxyethylene polyoxypropylene octadecanol ether, AP-type polyoxyethylene polyoxypropylene polyether, and AE-type polyoxyethylene polyoxypropylene polyether.

[0014] The present application II provides a method for preparing the well treatment agent according to any one of the present application I, comprising the following steps:

[0015] 1) dissolving the scale remover and the solubilizing agent in water to obtain a first solution;

[0016] 2) obtaining an alcohol to obtain a second solution;

[0017] 3) mixing the first solution and the second solution to obtain a third solution;

[0018] 4) adding the wetting agent to the third solution to obtain a fourth solution;

[0019] 5) adding the demulsifier to the fourth solution to obtain the well treatment agent.

[0020] The present application III provides the use of the well treatment agent according to any one of the present application I or prepared by the method according to the present application II in treating at least one of water lock damage, scale blockage, and emulsion damage.

[0021] Advantages of the present application:

[0022] The well bottom treatment agent of the present application can effectively reduce the surface tension of well bottom liquid accumulation, improve reservoir wettability, increase demulsification rate and scale inhibition rate, and achieve the purpose of removing complex pollution damage of low pressure and low yield well bottom in tight gas reservoir and purifying well bottom. The well bottom treatment agent can increase the core contact angle by 10.56°, and the surface tension can reach 29.41 mN·m -1 ; the core permeability recovery rate after the action of the well bottom purification treatment agent is up to 7 times or more; the demulsification rate is high, the condensate oil recovery rate is up to 90% or more; and the scale inhibition rate is up to 89% or more. After the well bottom purification treatment, the core permeability is obviously increased, the surface tension of the liquid accumulation is low, the scaling ions are not easy to scale, and the emulsion demulsification effect is good. The well bottom purification treatment agent can remove multiple types of pollution, has a wide application range, can improve the comprehensive effect of well bottom purification, ensure the overall production degree and the ultimate recovery rate of the whole gas reservoir, and improve the stable production effect of old wells. DETAILED DESCRIPTION

[0023] The present application will be further described below in combination with examples, but the examples of the present application are only exemplary descriptions, and the implementation manner does not constitute a limitation on the present application in any case.

[0024] Example 1

[0025] 1) : 10g of disodium ethylenediaminetetraacetate and 3g of potassium chloride were added to 80.1g of distilled water, and stirred uniformly to obtain a first solution;

[0026] 2) : 0.2g of isooctanol was dissolved in 0.5g of isopropyl alcohol, and stirred uniformly to obtain a second solution;

[0027] 3) : the first solution and the second solution were mixed and stirred uniformly to obtain a third solution;

[0028] 4) : 0.2g of octadecyl trimethyl ammonium chloride was added to the third solution, and stirred uniformly to obtain a fourth solution;

[0029] 5) : 6g of SP type polyoxyethylene polyoxypropylene octadecanol ether was added to the fourth solution, and stirred uniformly to obtain a well bottom treatment agent.

[0030] Table 1

[0031]

[0032] Example 2

[0033] 1) : 10g of disodium ethylenediaminetetraacetate and 3g of potassium chloride were added to 79.2g of distilled water, and stirred uniformly to obtain a first solution;

[0034] 2) : 0.2 g of dodecanol was dissolved in 0.6 g of ethanol, and stirred well to obtain a second solution;

[0035] 3) : The first solution and the second solution were mixed, and stirred well to obtain a third solution;

[0036] 4) : 1 g of polyetheramine D230 was added to the third solution, and stirred well to obtain a fourth solution;

[0037] 5) : 6 g of AP type polyoxyethylene polyoxypropylene polyether was added to the fourth solution, and stirred well to obtain a well treatment agent.

[0038] Table 2

[0039]

[0040] Example 3

[0041] 1) : 10 g of N-(2-hydroxyethyl)iminodiacetic acid and 3 g of potassium formate were added to 81.2 g of distilled water, and stirred well to obtain a first solution;

[0042] 2) : 0.2 g of isooctanol and 0.1 g of n-butanol were dissolved in 0.4 g of ethanol, and stirred well to obtain a second solution;

[0043] 3) : The first solution and the second solution were mixed, and stirred well to obtain a third solution;

[0044] 4) : 0.1 g of octadecyltrimethylammonium chloride was added to the third solution, and stirred well to obtain a fourth solution;

[0045] 5) : 5 g of AE type polyoxyethylene polyoxypropylene polyether was added to the fourth solution, and stirred well to obtain a well treatment agent.

[0046] Table 3

[0047]

[0048] Example 4

[0049] 1) : 10 g of aminotri(methylene)phosphonic acid tetrasodium and 3 g of potassium formate were added to 79.8 g of water, and stirred well to obtain a first solution;

[0050] 2) : 0.1 g of isooctanol and 0.2 g of propanol were dissolved in 0.5 g of ethanol, and stirred well to obtain a second solution;

[0051] 3) : The first solution and the second solution were mixed, and stirred well to obtain a third solution;

[0052] 4) : 0.1 g octadecyl trimethyl ammonium chloride, 0.3 g cetyl trimethyl ammonium chloride were added into the third solution and stirred well to obtain a fourth solution;

[0053] 5) : 6 g SP type polyoxyethylene polyoxypropylene octadecanol ether was added into the fourth solution and stirred well to obtain a well treatment agent.

[0054] Table 4

[0055]

[0056] Example 5

[0057] 1) : 10 g sodium diethylenetriamine pentaacetate and 3 g potassium chloride were added into 80.2 g water and stirred well to obtain a first solution;

[0058] 2) : 0.1 g dodecanol was dissolved in 0.6 g propyl alcohol and 0.3 g isopropyl alcohol and stirred well to obtain a second solution;

[0059] 3) : the first solution and the second solution were mixed and stirred well to obtain a third solution;

[0060] 4) : 0.5 g polyether amine D230 and 0.3 g cetyl trimethyl ammonium chloride were added into the third solution and stirred well to obtain a fourth solution;

[0061] 5) : 5 g AE type polyoxyethylene polyoxypropylene polyether was added into the fourth solution and stirred well to obtain a well treatment agent.

[0062] Table 5

[0063]

[0064] Example 6

[0065] 1) : 8 g disodium ethylenediaminetetraacetate and 2.4 g potassium formate were added into 81.9 g distilled water and stirred well to obtain a first solution;

[0066] 2) : 0.2 g dodecanol was dissolved in 0.7 g propyl alcohol and 0.3 g isopropyl alcohol and stirred well to obtain a second solution;

[0067] 3) : the first solution and the second solution were mixed and stirred well to obtain a third solution;

[0068] 4) : 0.5 g polyether amine D230 was added into the third solution and stirred well to obtain a fourth solution;

[0069] 5) : 6 g SP type polyoxyethylene polyoxypropylene octadecanol ether was added into the fourth solution and stirred well to obtain a well treatment agent.

[0070] Table 6

[0071]

[0072] Example 7

[0073] 1) : 10 g of disodium ethylenediaminetetraacetate and 3 g of potassium formate were added to 79.3 g of water, and stirred to obtain a first solution;

[0074] 2) : 0.2 g of dodecanol was dissolved in 0.7 g of propanol and 0.3 g of isopropanol, and stirred to obtain a second solution;

[0075] 3) : The first solution and the second solution were mixed and stirred to obtain a third solution;

[0076] 4) : 0.1 g of octadecyltrimethylammonium chloride and 0.4 g of hexadecyltrimethylammonium chloride were added to the third solution, and stirred to obtain a fourth solution;

[0077] 5) : 6 g of AP-type polyoxyethylene polyoxypropylene polyether was added to the fourth solution, and stirred to obtain a well treatment agent.

[0078] Table 7

[0079]

[0080] Example 8

[0081] 1) : 10 g of disodium ethylenediaminetetraacetate and 3 g of potassium formate were added to 79 g of water, and stirred to obtain a first solution;

[0082] 2) : 0.2 g of dodecanol was dissolved in 0.7 g of propanol and 0.3 g of isopropanol, and stirred to obtain a second solution;

[0083] 3) : The first solution and the second solution were mixed and stirred to obtain a third solution;

[0084] 4) : 0.5 g of polyetheramine D230 and 0.3 g of hexadecyltrimethylammonium chloride were added to the third solution, and stirred to obtain a fourth solution;

[0085] 5) : 6 g of AE-type polyoxyethylene polyoxypropylene polyether was added to the fourth solution, and stirred to obtain a well treatment agent.

[0086] Table 8

[0087]

[0088] Example 9

[0089] 1) : 10 g of disodium ethylenediaminetetraacetate and 3 g of potassium formate were added to 79.2 g of water, and stirred to obtain a first solution;

[0090] 2) : 0.2 g of n-butanol was dissolved in 0.5 g of ethanol and 0.3 g of isopropyl alcohol, and stirred to obtain a second solution;

[0091] 3) : The first solution and the second solution were mixed and stirred to obtain a third solution;

[0092] 4) : 0.5 g of polyetheramine D230 and 0.3 g of cetyltrimethylammonium chloride were added to the third solution, and stirred to obtain a fourth solution;

[0093] 5) : 6 g of AE type polyoxyethylene polyoxypropylene polyether was added to the fourth solution, and stirred to obtain a well treatment agent.

[0094] Table 9

[0095]

[0096] Example 10

[0097] 1) : 10 g of disodium ethylenediaminetetraacetate and 3 g of sodium formate were added to 79 g of water, and stirred to obtain a first solution;

[0098] 2) : 0.2 g of dodecanol was dissolved in 0.7 g of propanol and 0.3 g of isopropyl alcohol, and stirred to obtain a second solution;

[0099] 3) : The first solution and the second solution were mixed and stirred to obtain a third solution;

[0100] 4) : 0.5 g of polyetheramine D230 and 0.3 g of cetyltrimethylammonium chloride were added to the third solution, and stirred to obtain a fourth solution;

[0101] 5) : 6 g of AE type polyoxyethylene polyoxypropylene polyether was added to the fourth solution, and stirred to obtain a well treatment agent.

[0102] Table 10

[0103]

[0104] Comparative Example 1

[0105] 1) : 0.2 g of dodecanol was dissolved in 0.7 g of propanol and 0.3 g of isopropyl alcohol, and stirred to obtain a first solution;

[0106] 2) : 98 g of water was added to the first solution, and stirred to obtain a second solution;

[0107] 3): 0.5 g polyetheramine D230, 0.3 g cetyltrimethylammonium chloride were added into the second solution and stirred well to obtain the well treatment agent.

[0108] Table 11

[0109]

[0110] Comparative Example 2

[0111] 1): 10 g disodium ethylenediaminetetraacetate and 3 g potassium formate were added into 79.8 g water and stirred well to obtain a first solution;

[0112] 2): 0.2 g dodecanol was dissolved in 0.7 g propyl alcohol and 0.3 g isopropyl alcohol, and stirred well to obtain a second solution;

[0113] 3): the first solution and the second solution were mixed and stirred well to obtain a third solution;

[0114] 4): 6 g AE type polyoxyethylene polyoxypropylene polyether was added into the third solution and stirred well to obtain a well treatment agent.

[0115] Table 12

[0116]

[0117] Comparative Example 3

[0118] 1): 0.2 g dodecanol was dissolved in 0.7 g propyl alcohol and 0.3 g isopropyl alcohol, and stirred well to obtain a first solution;

[0119] 2): 92 g water was added into the first solution and stirred well to obtain a second solution;

[0120] 3): 0.5 g polyetheramine D230, 0.3 g cetyltrimethylammonium chloride were added into the second solution and stirred well to obtain a third solution;

[0121] 4): 6 g AE type polyoxyethylene polyoxypropylene polyether was added into the third solution and stirred well to obtain a well treatment agent.

[0122] Table 13

[0123]

[0124] Comparative Example 4

[0125] 1): 10 g disodium ethylenediaminetetraacetate and 3 g potassium formate were added into 85 g water and stirred well to obtain a first solution;

[0126] 2) : 0.2 g of dodecanol was dissolved in 0.7 g of propanol and 0.3 g of isopropanol, and stirred well to obtain a second solution;

[0127] 3) : the first solution was mixed with the second solution, and stirred well to obtain a third solution;

[0128] 4) : 0.5 g of polyetheramine and 0.3 g of cetyltrimethylammonium chloride were added to the third solution, and stirred well to obtain a well treatment agent.

[0129] Table 14

[0130]

[0131] Comparative Example 5

[0132] 1) : 10 g of disodium ethylenediaminetetraacetate and 3 g of potassium formate were added to 80.2 g of water, and stirred well to obtain a first solution;

[0133] 2) : 0.5 g of polyetheramine D230 and 0.3 g of cetyltrimethylammonium chloride were added to the first solution, and stirred well to obtain a second solution;

[0134] 3) : 6 g of AE type polyoxyethylene polyoxypropylene polyether was added to the second solution, and stirred well to obtain a well treatment agent.

[0135] Table 15

[0136]

[0137] Performance measurement

[0138] The well treatment agents prepared in each of the above examples and comparative examples were evaluated in terms of contact angle, surface tension, scale inhibition rate, condensate recovery rate, and core permeability recovery rate, and the specific experimental conditions and requirements were as follows:

[0139] 1. Contact angle

[0140] The contact angle was measured as follows:

[0141] I) A core hanging piece was prepared, and the thickness difference was required to be ≤0.1 mm, and was dried;

[0142] II) The contact angle between the core hanging piece without any treatment (blank control core hanging piece) and water was measured using a K100 surface tension meter contact angle measurement unit;

[0143] III) The core hanging piece was immersed in the well treatment agent and adsorbed for 24 h;

[0144] IV) The adsorbed core hanging piece was dried at a low temperature of less than 70°C to obtain an adsorbed and treated core hanging piece;

[0145] V) Measure the contact angle of the adsorption-treated core slice with water to investigate the change of the core contact angle after adsorption.

[0146] VI) Put the adsorption-treated core slice into water for desorption for 24 h, and dry at a low temperature of less than 70°C to obtain a desorption-treated core slice;

[0147] VII) Measure the contact angle of the desorption-treated core slice with water to investigate the change of the core contact angle after desorption.

[0148] The results are shown in Table 16.

[0149] Table 16

[0150]

[0151] 2. Core permeability change rate

[0152] Measurement method: According to the provisions in Chapter 12 of the Working Fluid Evaluation Method in Q / SH 0501-2013 Evaluation Method for Sensitivity Flow of Dense Reservoirs.

[0153] I) Experimental core and liquid preparation: The porosity, permeability and length of the experimental core are basically consistent; the experimental liquid is a well treatment agent.

[0154] II) Establish the water saturation of the experimental core (60%-70%).

[0155] III) Measure the initial permeability of the core with nitrogen.

[0156] IV) Reverse squeeze the well treatment agent into the core for 24 h.

[0157] V) Simulate the gas production process to perform flowback, measure the permeability of the core after 24 h of flowback, and calculate the permeability recovery rate.

[0158] The results are shown in Table 17.

[0159] Table 17

[0160] Example Initial permeability / x 10 -3 μm 2 ]]> Return 24 h permeability / x 10 -3 μm 2 ]]> % permeability recovery Example 1 0.02196 0.14581 664 Example 2 0.02412 0.16932 702 Example 3 0.06774 0.42134 622 Example 4 0.000944 0.00605 641 Example 5 0.000712 0.00459 645 Example 6 0.000545 0.00378 693 Example 7 0.000319 0.00214 672 Example 8 0.00434 0.03086 711 Example 9 0.00445 0.03057 687 Example 10 0.00317 0.02111 666 Comparative Example 1 0.00257 0.01509 587 Comparative Example 2 0.00156 0.00552 354 Comparative Example 3 0.00562 0.03344 595 Comparative Example 4 0.01029 0.05207 506 Comparative Example 5 0.00289 0.00160 55.3

[0161] 3. Surface tension

[0162] The surface tension of the well treatment agent of each example and the comparative example was measured according to the provisions in SY / T 5370-2018 Determination Method for Surface and Interfacial Tension.

[0163] The results are shown in Table 18.

[0164] 4. Scale inhibition performance

[0165] The scale inhibition performance of the well bottom treatment agent of each example and the comparative example was determined according to GB / T 16632-2019 “Determination of Scale Inhibition Performance of Water Treatment Agent by Calcium Carbonate Deposition Method”.

[0166] The results are shown in Table 18.

[0167] 5. demulsification effect

[0168] I) Preparation of mineralized water: NaCl, CaCl2, MgCl2 were prepared into 40 g / L mineralized water at a mass ratio of 4:0.875:0.125;

[0169] II) Emulsion preparation: 1 g of dodecyl dimethyl amine oxide, 14 g of 40 g / L mineralized water and 85 mL of kerosene were mixed, stirred at a speed of 4000 r / min for 2 min to prepare the emulsion, and used immediately.

[0170] III) Condensate recovery rate determination: the emulsion was transferred into a graduated cylinder with a stopper, 1 mL of the well bottom treatment agent of each example and the comparative example was added into the graduated cylinder containing the emulsion with a pipette, the stopper was added, and the graduated cylinder was shaken by hand for 20 times, then it was left to stand, and the volume V of the oil discharged in 30 min was recorded. The condensate recovery rate was calculated according to the following formula:

[0171]

[0172] The results are shown in Table 18.

[0173] Table 18

[0174] Example Surface tension / mN.m -1 ]]> % scale inhibition % condensate recovery Example 1 31.29 89.46 94.71 Example 2 29.41 90.54 95.88 Example 3 30.46 88.56 92.94 Example 4 31.19 90.12 96.47 Example 5 30.19 89.09 92.35 Example 6 30.51 88.87 94.12 Example 7 30.76 91.97 95.29 Example 8 30.66 92.76 96.47 Example 9 30.84 92.04 94.71 Example 10 31.46 91.98 95.29 Comparative Example 1 31.03 6.75 11.76 Comparative Example 2 33.02 91.31 81.76 Comparative Example 3 30.43 7.23 81.18 Comparative Example 4 31.11 90.54 12.35 Comparative Example 5 59.23 89.91 82.94

[0175] According to Tables 16 to 18, the well bottom treatment agent prepared in the above examples of the present application has a low surface tension, can increase the core contact angle, improve the core permeability recovery rate, has a good demulsification effect, a high condensate recovery rate and a high scale inhibition rate. The comparative examples 1 to 5 are prepared by reducing different functional raw materials based on example 8, which leads to the limitation of the treatment agent in removing pollution. It can be seen that the raw materials in the present application have good compatibility and can play a role in removing various pollution, and have a wide application range and can improve the comprehensive effect of well bottom purification.

[0176] In summary, through the comparative analysis of the examples and the comparative examples, the well bottom treatment agent of the present application has better technical effects, which is the result of the synergistic effect of the components.

[0177] While the application has been described with reference to particular embodiments thereof, it is to be understood that variations and modifications can be affected without departing from the spirit and scope of the application. Further, it is to be understood that the application can be practiced by employing other particular operating conditions, materials, materials combinations, and methods without departing from the spirit and scope of the application. All such variations and modifications are to be included within the scope of the following claims.

Claims

1. A bottom-hole treatment agent comprising an alcohol, a descaling agent, a solubilizer, a wetting agent, a demulsifier, and water; The total mass of the bottom-hole treatment agent is 100%, and the alcohol content is 0.7% to 1.2%; the descaling agent content is 8% to 10%; the solubilizer content is 2.4% to 3%; the wetting agent content is 0.1% to 1%; the demulsifier content is 5% to 6%; and the balance is water.

2. The bottom hole treatment agent according to claim 1, characterized in that, The alcohol is at least two of ethanol, propanol, isopropanol, n-butanol, isooctyl alcohol, and dodecanol.

3. The bottom hole treatment agent according to claim 1, characterized in that, The descaling agent is at least one of disodium ethylenediaminetetraacetate, N-(2-hydroxyethyl)iminodiacetic acid, tetrasodium aminotrimethylenephosphonate, and sodium diethylenetriaminepentaacetate.

4. The bottom hole treatment agent according to claim 1, characterized in that, The solubilizer is at least one of potassium chloride, potassium formate, and sodium formate.

5. The bottom hole treatment agent according to claim 1, characterized in that, The wetting agent is at least one of octadecyltrimethylammonium chloride, polyetheramine D230, and hexadecyltrimethylammonium chloride.

6. The bottom hole treatment agent according to claim 1, characterized in that, The demulsifier is a polyether-based demulsifier.

7. The bottom hole treatment agent according to claim 6, characterized in that, The demulsifier is at least one of SP type polyoxyethylene polyoxypropylene octadecyl alcohol ether, AP type polyoxyethylene polyoxypropylene polyether, and AE type polyoxyethylene polyoxypropylene polyether.

8. A method for preparing the bottom hole treatment agent as described in any one of claims 1 to 7, comprising the following steps: 1) Dissolve the descaling agent and solubilizer in water to obtain a first solution; 2) Obtain the alcohol, and then obtain the second solution; 3) Mix the first solution and the second solution to obtain a third solution; 4) Add the wetting agent to the third solution to obtain the fourth solution; 5) Add the demulsifier to the fourth solution to obtain the bottom hole treatment agent.

9. The application of the bottom-hole treatment agent according to any one of claims 1 to 7 or the bottom-hole treatment agent prepared according to the method of claim 8 in the treatment of at least one of water-locking damage, scale blockage and emulsion damage at the bottom of the well.

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