A kind of oil test completion fluid and its preparation method and application

Abstract

The present invention provides a well test completion fluid, a preparation method, and an application thereof. The well test completion fluid comprises the following components, measured by weight: 30-60 parts water, 90-100 parts weighting material, 5-10 parts surface modifier, 5-8 parts stabilizer, 8-10 parts surface charge and steric hindrance modifier, and 8-10 parts dispersant. The well test completion fluid exhibits good rheological properties and sedimentation stability after standing at 200°C for 15 days. Furthermore, the well test completion fluid exhibits good compatibility with drilling fluid, cement, diesel, or acid.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil and gas exploration and development, and relates to an oil test completion fluid, a preparation method and application thereof, and in particular to a long-lasting, stable, high-density water-based oil test completion fluid, a preparation method and application thereof. Background Art

[0002] As oil and gas exploration and development develop towards deep and ultra-deep wells and unconventional shale oil and gas reservoirs, well depths exceeding 6,000 meters are associated with high downhole temperatures and large pressure coefficients. Currently, deep well test and completion fluids are essentially directly converted from drilling fluids. Due to the complex procedures and long test cycles associated with high-temperature and high-pressure deep well testing, high-density drilling and completion fluids are prone to system performance deterioration, treatment agent failure, and material sedimentation during prolonged high-temperature testing. This can lead to complex problems such as test string blockage, inability to set / release packers, and difficulty starting pumps. Furthermore, these fluids can clog oil and gas flow channels, contaminate reservoirs, and affect production, severely impacting the speed and efficiency of test and completion.

[0003] The solid-free completion fluid currently in use has a low density and cannot meet the high pressure coefficient requirements of deep wells. The oil test completion fluid easily forms flocculants, precipitates, cements, etc. after contact with drilling fluid, cement, diesel, and acid, and has poor compatibility, which blocks the oil and gas layers and blocks the surface pipelines when the wellbore working fluid flows back. There are also patent documents reporting on oil test completion fluids. For example, CN110028938A provides an ultra-high temperature and high density oil test completion fluid and its preparation method. The oil test completion fluid is composed of water, dispersant, stabilizer, salt, high temperature protective agent, high temperature flow pattern regulator, and weighting agent, and has a density of 1.5-2.4g / cm 3 , has good compatibility with oil-based drilling fluids, but does not specify its compatibility with cement, diesel, and acid. 50 Distributed in the range of 0.1-0.8 μm, it belongs to ultrafine barite, which is expensive and not conducive to popularization and application. CN107033863A provides a solid-phase, pollution-free, low-damage, high-density completion fluid and its preparation method. The completion fluid includes potassium hydroxide, potassium dihydrogen phosphate, potassium monohydrogen phosphate, potassium formate, potassium pyrophosphate, cesium formate, viscosity enhancer, fluid loss reducer and water, with a density of 1.7-1.9 g / cm 3 However, the density is low and cannot meet the density requirements of test completion fluids in ultra-deep well drilling. In addition, potassium formate and cesium formate are expensive, which is not conducive to their promotion and application. CN108913109A provides a long-lasting and stable water-based completion fluid, whose components include bentonite, high-temperature resistant viscosity enhancer, NaOH, high-temperature resistant fluid loss reducer, high-temperature resistant stabilizer, high-temperature plugging material, high-temperature resistant lubricant, water and barite, with a density of 1.8 to 2.4 g / cm 3, has a certain degree of high-temperature resistance and long-term sedimentation stability, but the high-temperature resistant viscosity enhancer in the component is polyanionic cellulose, which generally can only maintain its viscosity for 48 hours at 150°C (see "Practical Handbook of Drilling Fluid Treatment Agents" published by China Petrochemical Press, page 72, December 2016). In addition, the component does not contain a dispersant that is very important for high-temperature static sedimentation stability. Therefore, it is difficult to achieve stability of this water-based completion fluid for 30 days at 200°C.

[0004] The existing conventional oil test completion fluid has the following disadvantages: (1) Low density. The density of solid-free oil test completion fluid is 1.7-1.9 g / cm 3 , which cannot meet the requirements of deep and ultra-deep wells for completion fluid density; (2) The raw materials are expensive, which is not conducive to promotion and application.

[0005] Therefore, there is an urgent need to develop a low-cost, long-lasting, stable, high-density water-based oil testing completion fluid in this field. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a well testing and completion fluid, its preparation method, and its application, particularly a long-lasting, stable, high-density water-based well testing and completion fluid, its preparation method, and its application. This well testing and completion fluid exhibits excellent rheological properties and sedimentation stability at high temperatures, and exhibits good compatibility with drilling fluids, cement, diesel, and acid, making it suitable for use in well testing and completion operations in deep and ultra-deep wells.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a well testing and completion fluid, which comprises the following components, in parts by weight: 30 to 60 parts of water, 90 to 100 parts of weighting material, 5 to 10 parts of surface modifier, 5 to 8 parts of stabilizer, 8 to 10 parts of surface charge and steric hindrance regulator, and 8 to 10 parts of dispersant.

[0009] The functions of the components in the present invention are as follows: the surface charge and steric hindrance regulators produce a strong electrostatic repulsion effect by increasing the absolute value of the surface potential of the weighting material particles, and can also induce a strong steric repulsion effect. The dispersant can prevent the weighting material particles from settling and agglomerating in water. The surface modifier can combine the weighting material and the dispersant. The stabilizer improves the wettability at the liquid-solid interface, improves the compatibility between the liquid phase and the solid phase, and allows the particles to be stably dispersed and suspended in water without agglomeration, thereby improving the stability of the test oil completion fluid. Through the synergistic effect of the above-mentioned components, the present invention provides a test oil completion fluid that still has good rheology and sedimentation stability after standing at 200°C for 15 days, and the test oil completion fluid still has good rheology and sedimentation stability after being contaminated by drilling fluid, cement, diesel or acid (such as mud acid), and has good compatibility with drilling fluid, cement, diesel or acid.

[0010] In the present invention, the amount of water in the components of the oil testing and completion fluid can be 30 parts, 33 parts, 35 parts, 38 parts, 40 parts, 43 parts, 45 parts, 48 ​​parts, 50 parts, 53 parts, 55 parts, 58 parts or 60 parts, etc., calculated by weight.

[0011] In the present invention, the amount of weighting material in the components of the oil testing completion fluid can be 90 parts, 91 parts, 92 parts, 93 parts, 94 parts, 95 parts, 96 parts, 97 parts, 98 parts, 99 parts or 100 parts, etc., calculated by weight.

[0012] In the present invention, the amount of the surface modifier in the components of the oil testing and completion fluid can be 5 parts, 6 parts, 7 parts, 8 parts, 9 parts or 10 parts, etc., calculated by weight.

[0013] In the present invention, the amount of the stabilizer in the components of the oil testing and completion fluid can be 5 parts, 6 parts, 7 parts or 8 parts, etc., calculated by weight.

[0014] In the present invention, the amount of the surface charge and steric hindrance regulator in the components of the oil testing and completion fluid can be 8 parts, 9 parts or 10 parts by weight.

[0015] In the present invention, the amount of the dispersant in the components of the oil testing and completion fluid can be 8 parts, 9 parts or 10 parts by weight.

[0016] Preferably, the density of the oil test completion fluid is 1.7-2.4 g / cm 3 , for example 1.7 g / cm 3 , 1.8g / cm 3 , 1.9g / cm 3 , 2.0g / cm 3 , 2.1g / cm 3 , 2.2g / cm 3 , 2.3g / cm 3 or 2.4g / cm 3 The oil testing and completion fluid provided by the present invention has a wide density range and can meet the density requirements of the oil testing and completion fluid for ultra-deep well drilling.

[0017] Preferably, the weighting material comprises any one of iron ore powder, barite or manganese ore powder, or a combination of at least two of them. When two of the above substances are used as weighting materials, they can be mixed in any mass ratio.

[0018] Preferably, the surface modifier comprises any one of a silane coupling agent, a titanate coupling agent, or an aluminate coupling agent, or a combination of at least two thereof. The surface modifier of the present invention is a coupling agent, which is an amphoteric substance. A portion of the molecule has hydrophilic polar groups that can form chemical bonds with functional groups on the surface of the weighting material, while another portion has hydrophobic groups that can chemically react or entangle with the organic molecular dispersant, thereby combining the weighting material and the organic molecular dispersant.

[0019] Preferably, the stabilizer comprises a polyol.

[0020] Preferably, the stabilizer includes any one of ethylene glycol, glycerol or mannitol, or a combination of at least two of them, preferably a combination of ethylene glycol and glycerol (the two can be mixed in any mass ratio).

[0021] Preferably, the surface charge and steric hindrance regulator comprises any one of aluminum sulfate, magnesium sulfate or zinc sulfate, or a combination of at least two thereof.

[0022] Preferably, the dispersant is an organic molecular dispersant, including any one of sodium polyacrylate, ammonium polyacrylate or sodium dodecylbenzene sulfonate, or a combination of at least two thereof.

[0023] In a second aspect, the present invention provides a method for preparing the oil testing and completion fluid according to the first aspect, the preparation method comprising the following steps:

[0024] The formulated amounts of water, weighting material, surface modifier, stabilizer, surface charge and steric hindrance regulator and dispersant are mixed to obtain a mixed liquid, and the mixed liquid is ground to obtain the oil testing completion fluid.

[0025] The preparation method of the oil testing and completion fluid provided by the invention is simple, and the raw materials are widely available and inexpensive.

[0026] Preferably, the mixing of the formulated amount of water, weighting material, surface modifier, stabilizer, surface charge and steric hindrance regulator and dispersant specifically includes the following steps: under stirring, adding the weighting material, surface modifier, stabilizer, surface charge and steric hindrance regulator and dispersant to water in sequence and mixing them.

[0027] Preferably, the stirring speed is 70-100 rpm, such as 70 rpm, 80 rpm, 90 rpm or 100 rpm.

[0028] Preferably, the grinding is performed at room temperature.

[0029] Preferably, the grinding is grinding to the D of the weighted material. 50The particle size is 1.0-1.5 μm, for example, 1.0 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm or 1.5 μm, etc. The particle size can be measured using a laser particle size analyzer such as Malvern 2000 or similar products.

[0030] In a third aspect, the present invention provides a use of the oil testing and completion fluid as described in the first aspect in drilling, completion and oil testing working fluid.

[0031] Preferably, the oil testing and completion fluid is used in oil testing and completion operations at a downhole temperature of 200° C. or above.

[0032] Compared with the prior art, the present invention has at least the following beneficial effects:

[0033] (1) The oil test completion fluid provided by the present invention has a wide density range and can meet the density requirements of the oil test completion fluid for ultra-deep well drilling;

[0034] (2) The oil test completion fluid provided by the present invention still has good rheological properties and sedimentation stability after being left at 200°C for more than 15 days;

[0035] (3) The oil test completion fluid provided by the present invention still has good rheological properties and sedimentation stability after being contaminated by drilling fluid, cement, diesel or acid (such as mud acid), and has good compatibility with drilling fluid, cement, diesel or acid;

[0036] (4) The preparation method of the oil test completion fluid provided by the present invention is simple, and the raw materials are widely available and inexpensive. DETAILED DESCRIPTION

[0037] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0038] Meanwhile, the experimental methods described in the following examples, unless otherwise specified, are conventional methods; the reagents and materials, unless otherwise specified, can be obtained from commercial channels.

[0039] Example 1

[0040] In this embodiment, a well test completion fluid is provided. The well test completion fluid comprises the following components, in parts by weight: 30 parts of water, 100 parts of weighting material, 10 parts of surface modifier, 8 parts of stabilizer, 10 parts of surface charge and steric hindrance regulator, and 10 parts of dispersant.

[0041] The weighting material is barite; the surface modifier is a combination of silane coupling agent KH550 (5 parts) and titanate coupling agent 201 (5 parts); the stabilizer is a combination of ethylene glycol (4 parts) and glycerol (4 parts); the surface charge and steric hindrance regulator is magnesium sulfate; the dispersant is a combination of sodium polyacrylate (molecular weight 5000, 5 parts) and sodium dodecylbenzene sulfonate (5 parts); the density of the test completion fluid is 2.4 g / cm 3 .

[0042] The preparation method comprises the following steps:

[0043] Under the stirring state of 80 rpm, the weighting material, surface modifier, stabilizer, surface charge and steric hindrance regulator and dispersant are added to the water in sequence and mixed to obtain a mixed solution, which is ground at room temperature until the weighting material D 50 The particle size of the wellbore is 1.0 μm, and the well testing completion fluid is obtained.

[0044] Example 2

[0045] In this embodiment, a well test completion fluid is provided. The well test completion fluid comprises the following components, in parts by weight: 40 parts of water, 96 parts of weighting material, 8 parts of surface modifier, 7 parts of stabilizer, 9 parts of surface charge and steric hindrance regulator, and 9 parts of dispersant.

[0046] Among them, the weighting material is barite; the surface modifier is a combination of silane coupling agent KH550 (4 parts) and titanate coupling agent 201 (4 parts); the stabilizer is a combination of ethylene glycol (4 parts) and glycerol (3 parts); the surface charge and steric hindrance regulator is a combination of aluminum sulfate (5 parts) and magnesium sulfate (4 parts); the dispersant is a combination of sodium polyacrylate (molecular weight 5000, 5 parts) and sodium dodecylbenzene sulfonate (4 parts); the density of the oil test completion fluid is 2.1g / cm 3 .

[0047] The preparation method comprises the following steps:

[0048] Under the stirring state of 70 rpm, the weighting material, surface modifier, stabilizer, surface charge and steric hindrance regulator and dispersant were added to the water in sequence and mixed to obtain a mixed solution, which was ground at room temperature until the weighting material D 50 The particle size of the wellbore is 1.2 μm, and the well testing completion fluid is obtained.

[0049] Example 3

[0050] In this embodiment, a well test completion fluid is provided. The well test completion fluid comprises the following components, in parts by weight: 60 parts of water, 90 parts of weighting material, 5 parts of surface modifier, 5 parts of stabilizer, 8 parts of surface charge and steric hindrance regulator, and 8 parts of dispersant.

[0051] The weighting material is barite; the surface modifier is a combination of silane coupling agent KH550 (3 parts) and titanate coupling agent 201 (2 parts); the stabilizer is a combination of ethylene glycol (3 parts) and glycerol (2 parts); the surface charge and steric hindrance regulator is a combination of aluminum sulfate (4 parts) and magnesium sulfate (4 parts); the dispersant is a combination of polyacrylamide (molecular weight 10,000, 4 parts) and sodium dodecylbenzene sulfonate (4 parts); the density of the test completion fluid is 1.7 g / cm 3 .

[0052] The preparation method comprises the following steps:

[0053] Under the stirring state of 100 rpm, the weighting material, surface modifier, stabilizer, surface charge and steric hindrance regulator and dispersant are added to the water in sequence and mixed to obtain a mixed solution, which is ground at room temperature until the weighting material D 50 The particle size of the wellbore is 1.5 μm, and the well testing completion fluid is obtained.

[0054] Comparative Example 1

[0055] The only difference between this comparative example and Example 1 is that the components in the oil testing and completion fluid do not include surface charge and steric hindrance regulators.

[0056] Comparative Example 2

[0057] The only difference between this comparative example and Example 1 is that the surface charge and steric hindrance regulators are replaced by an equal amount of triethanolamine.

[0058] The rheological properties and sedimentation stability of the oil testing completion fluid provided by the present invention were evaluated. The evaluation experimental process is as follows:

[0059] (1) The sample of the present invention was stirred in a high-speed stirrer at 5000 rpm for 5 min, removed, and if bubbles were present, gently stirred with a glass rod or 1-2 drops of defoaming agent were added to remove the bubbles. The density was then tested, and the rheological properties were tested at room temperature according to GB / T 16783.1-2006 "Field Test Procedure for Water-Based Drilling Fluids";

[0060] (2) 400 mL of the above sample was placed in four high-temperature aging tanks, placed in a constant temperature drying oven (upright), and aged at 200°C;

[0061] (3) Take out one aging tank after aging for 5, 7, 10, and 15 days respectively, place it upright in a water tank and cool it with water. When it cools to room temperature, open the aging tank and place it on the sample table of the needle-penetration sinking degree tester. Select 4 points on the liquid surface of the aging tank to measure the sinking degree, record the maximum reaction force during the descent process, and calculate the average value of the 4 points as the sinking degree test result, so as to characterize the sinking stability of the test completion fluid. Then stir the sample evenly and pour it into a high-stirring cup. Stir it at 5000 rpm on a high-speed mixer for 5 minutes. Remove it. If there are bubbles, stir it lightly with a glass rod or add 1-2 drops of defoaming agent to defoam. Test its rheological properties at room temperature according to GB / T 16783.1-2006 "Field Test Procedure for Water-Based Drilling Fluids".

[0062] The rheological properties and sedimentation stability test results of the oil testing and completion fluids provided in Examples 1-3 of the present invention are shown in Tables 1-3, respectively.

[0063] Table 1

[0064]

[0065] Table 2

[0066]

[0067] Table 3

[0068]

[0069] As can be seen from Tables 1 to 3, the oil test completion fluids provided in Examples 1 to 3 of the present invention have little change in apparent viscosity, plastic viscosity, dynamic shear force, and initial shear force after aging at 200°C for 15 days with increasing high-temperature aging time. The final shear force is relatively large when the completion fluid is just prepared, but decreases and remains stable after 5 days of static aging. The solidity is less than 2N, and there is basically no sedimentation at high temperature. This indicates that the oil test completion fluids provided by the present invention still have good rheological properties and sedimentation stability during long-term downhole operations at 200°C, and can meet the requirements of oil test operations in high-temperature deep wells.

[0070] Referring to the above, the sedimentation stability test of the oil test completion fluid provided in Comparative Examples 1-2 of the present invention was carried out. The test results are shown in Table 4:

[0071] Table 4

[0072]

[0073] As can be seen from Table 4, in Comparative Example 1, no surface charge and steric hindrance modifier is added, and the degree of sedimentation after aging at 200°C for 15 days is 2.98 times that of Example 1, and its sedimentation stability is significantly deteriorated, which cannot meet the requirements of on-site oil testing operations; in Comparative Example 2, triethanolamine is used as the surface charge and steric hindrance modifier, and the degree of sedimentation after aging at 200°C for 15 days is 1.46 times that of Example 1, and the sedimentation stability is also deteriorated.

[0074] To investigate the compatibility of the test completion fluid of the present invention with drilling fluid, a drilling fluid contamination experiment was conducted. The test completion fluid from Example 1 was mixed with a field drilling fluid at varying ratios for evaluation. The rheological properties and sedimentation stability of the mixed test completion fluid and drilling fluid were examined. The field drilling fluid composition was: 2% soil slurry + 0.5% NaOH + 0.5% composite ionic polyacrylate + 5% humic acid acrylic acid amide multi-polymer + 5% sulfomethyl phenolic resin + 3% methyl oleate + 0.3% SP-80 + 20% barite.

[0075] (1) Experimental samples

[0076] The water-based oil testing completion fluid of Example 1 was mixed with the drilling fluid at volume ratios of 9:1, 7:3, and 5:5, respectively.

[0077] (2) Experimental steps

[0078] First, the test completion fluid of Example 1 was stirred evenly. Then, different volume ratios of drilling fluid were added at room temperature and stirred at 5000 rpm for 20 minutes. The rheological properties of the slurry were tested. The slurry was then placed in an aging tank and aged at 200°C for 7 days. The rheological properties and sedimentation stability of the slurry were then measured at room temperature.

[0079] The test results are shown in Table 5.

[0080] Table 5

[0081]

[0082] As can be seen from Table 5, with the increase of the drilling fluid slurry volume, the viscosity gradually increases after leaving the tank, and 1-5 mm of liquid precipitates in the upper part of the slurry. However, the slurry in the middle and lower part of the aging tank has no precipitation or solidification, and there are no obvious lumps in the slurry stirred with a glass rod. From the solidity results, it can be seen that with the increase of the slurry ratio, the solidity of the system increases. This shows that the oil test fluid system still has good rheological properties and sedimentation stability when mixed with the well slurry at a volume ratio of no more than 1:1 at 200°C.

[0083] To investigate the compatibility of the test completion fluid of the present invention with cement, a cement contamination experiment was conducted. The test completion fluid of Example 1 was mixed with cement at different ratios to test the rheological properties and sedimentation stability of the mixed fluid.

[0084] (1) Experimental samples

[0085] After solidification, ordinary cement was ground and passed through a 100-mesh sieve. The water-based oil testing completion fluid of Example 1 was mixed with cement to obtain a mixed solution. The amount of cement added was 1%, 2%, and 3% of the total volume of the mixed solution, respectively.

[0086] (2) Experimental steps

[0087] First, the test completion fluid was stirred evenly. Then, 1%, 2%, and 3% cement were added respectively at room temperature and stirred at 5000 rpm for 20 minutes. The density and rheological properties of the slurry were tested. The slurry was then placed in an aging tank and aged at 200°C for 24 hours. The rheological properties and sedimentation stability of the mixture of the test completion fluid and cement were measured at room temperature.

[0088] The test results are shown in Table 6.

[0089] Table 6

[0090]

[0091] As can be seen from Table 6, the oil testing completion fluid of the present invention still has good rheological properties and sedimentation stability after static aging at 200° C. for 24 hours under the condition of cement contamination.

[0092] In order to investigate the oil test completion fluid of the present invention under the condition of on-site diesel and mud acid contamination, an evaluation experiment was conducted by mixing the oil test completion fluid in Example 1 with diesel and mud acid in a volume ratio of 10:1 to test the rheological properties and sedimentation stability of the oil test completion fluid after mixing with diesel and mud acid.

[0093] (1) Experimental samples

[0094] The water-based well test completion fluid of Example 1 was mixed with mud acid at a volume ratio of 10:1, wherein the mud acid composition was 6% hydrochloric acid + 3% hydrofluoric acid;

[0095] The water-based well testing completion fluid of Example 1 was mixed with diesel fuel at a volume ratio of 10:1, where the diesel fuel was ordinary diesel fuel.

[0096] (2) Experimental steps

[0097] First, the test completion fluid of Example 1 was stirred evenly, and then mud acid and diesel were added separately at room temperature and stirred at 5000 rpm for 20 minutes. The density and rheological properties of the mixed solution were tested. The mixed solution was then placed in an aging tank and aged at 200°C for 24 hours. The rheological properties and sedimentation stability of the mixed solution were then measured at room temperature.

[0098] The test results are shown in Table 7.

[0099] Table 7

[0100]

[0101] As can be seen from Table 7, the well test completion fluid still has good rheological properties and sedimentation stability after static aging at 200℃ for 24h under the contamination of mud acid and diesel.

[0102] In summary, the oil test completion fluid provided by the present invention still has good rheological properties and sedimentation stability after being allowed to stand at 200°C for 15 days; moreover, the oil test completion fluid provided by the present invention still has good rheological properties and sedimentation stability after being contaminated by drilling fluid, cement, diesel or mud acid, and has good compatibility with drilling fluid, cement, diesel or acid.

[0103] The applicant declares that while the above-described embodiments illustrate the oil testing and completion fluid, its preparation method, and its application, the present invention is not limited to these embodiments, nor does it necessarily rely on these embodiments for implementation. Those skilled in the art will appreciate that any improvements to the present invention, equivalent substitutions for raw materials in the present invention, addition of auxiliary components, and selection of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

Claims

1. A well testing and completion fluid, characterized in that: The oil test completion fluid comprises the following components in parts by weight: 30 to 60 parts of water, 90 to 100 parts of weighting material, 5 to 10 parts of surface modifier, 5 to 8 parts of stabilizer, 8 to 10 parts of surface charge and steric hindrance regulator, and 8 to 10 parts of dispersant; The surface modifier includes any one of a silane coupling agent, a titanate coupling agent or an aluminate coupling agent, or a combination of at least two thereof; The stabilizer includes a polyol; The surface charge and steric hindrance regulator includes any one of aluminum sulfate, magnesium sulfate or zinc sulfate or a combination of at least two thereof; The dispersant includes any one or a combination of at least two of sodium polyacrylate, ammonium polyacrylate or sodium dodecylbenzene sulfonate; The weighting material includes any one of iron ore powder, barite or manganese ore powder, or a combination of at least two of them; The preparation method of the oil test completion fluid comprises the following steps: mixing a formulated amount of water, a weighting material, a surface modifier, a stabilizer, a surface charge and steric hindrance regulator, and a dispersant to obtain a mixed liquid, and grinding the mixed liquid to obtain the oil test completion fluid.

2. The oil testing completion fluid according to claim 1, characterized in that: The density of the oil testing and completion fluid is 1.7-2.4 g / cm3.

3. The oil testing completion fluid according to claim 1, characterized in that: The stabilizer includes any one of ethylene glycol, glycerol or mannitol, or a combination of at least two of them.

4. The oil testing completion fluid according to claim 3, characterized in that: The stabilizer includes a combination of ethylene glycol and glycerol.

5. A method for preparing a well test completion fluid according to any one of claims 1 to 4, characterized in that: The preparation method comprises the following steps: The formulated amounts of water, weighting material, surface modifier, stabilizer, surface charge and steric hindrance regulator and dispersant are mixed to obtain a mixed liquid, and the mixed liquid is ground to obtain the oil testing completion fluid.

6. The preparation method according to claim 5, characterized in that The method of mixing the formulated amount of water, weighting material, surface modifier, stabilizer, surface charge and steric hindrance regulator and dispersant specifically includes the following steps: adding the weighting material, surface modifier, stabilizer, surface charge and steric hindrance regulator and dispersant to water in sequence and mixing them under stirring.

7. The preparation method according to claim 6, characterized in that The stirring speed is 70-100 rpm.

8. The preparation method according to claim 5, characterized in that The grinding is carried out at room temperature.

9. The preparation method according to claim 5, characterized in that The grinding is grinding to the D of the weighted material 50 1.0-1.5 microns.

10. Use of the oil testing and completion fluid according to any one of claims 1 to 4 in drilling, completion and oil testing working fluid.

11. The use according to claim 10, characterized in that The oil testing and completion fluid is used in oil testing and completion operations at downhole temperatures above 200°C.

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