Process for the preparation of oil well cement retarder and its application

Abstract

The application belongs to the field of oil field additives, and particularly relates to a preparation method of an oil well cement retarder and application thereof. The method comprises the following steps: (1) performing first reaction on a stabilizer, tartaric acid, sodium glucoheptonate, sodium gluconate and water to obtain a first product; (2) performing preliminary mixing on the first product and graphene to obtain a preliminary mixing product, and performing ultrasonic mixing on the preliminary mixing product to obtain a uniformly mixed product; and (3) performing second reaction on the uniformly mixed product to obtain the oil well cement retarder. The oil well cement retarder prepared by the method has simple preparation process, good stability and excellent performance.

Description

Technical Field

[0001] This invention belongs to the field of oilfield additives, specifically relating to an oil well cement retarder, its preparation method, and its application. Background Technology

[0002] China is entering a strategic period of opportunity for the parallel development of conventional and unconventional oil and gas, and the market size for deep and ultra-deep well services is continuously growing. However, the high bottom-hole temperature, long cemented sections, and large temperature differences in deep and ultra-deep wells, which make it difficult to achieve top strength, have become bottlenecks restricting oil and gas exploration and development.

[0003] In open-hole cementing operations with large temperature differences and long boreholes, the dosage of retarders is sensitive or ineffective under high temperature and high pressure conditions, leading to shortened or irregular cement slurry thickening time. After construction, the delayed setting of the top of the long cemented section can cause gas leakage and seal integrity failure. Retarder technology is a key research focus and a challenge. While ensuring controllable cement slurry thickening time, it is necessary to address the issue of delayed strength development of cement stone during the setting period.

[0004] Solving the technical challenges of cementing projects with large temperature differences can begin with improving the cement slurry system and optimizing the cementing process. However, the most fundamental and effective solution is to develop high-temperature resistant and stable organic retarder, and further combine it with inorganic functional materials that are compatible with cement slurry. If a new type of oil well cement retarder can be developed through an inorganic-organic hybrid method, it should be able to solve the aforementioned problems in cementing technology with large temperature differences. Summary of the Invention

[0005] The purpose of this invention is to overcome the aforementioned technical problems in the prior art and provide a method for preparing an oil well cement retarder and its application. The oil well cement retarder prepared using the method of this invention exhibits excellent stability, and the cement slurry formulated with this retarder has a superior thickening time. Furthermore, this oil well cement retarder combines the characteristics of inorganic material filling and reinforcement, significantly improving the mechanical properties of the solidified cement slurry.

[0006] The first aspect of this invention provides a method for preparing an oil well cement retarder, the method comprising the following steps:

[0007] (1) The stabilizer, tartaric acid, sodium gluconate, sodium gluconate and water were reacted to obtain the first product;

[0008] (2) The first product is initially mixed with graphene to obtain an initial mixed product, and the initial mixed product is ultrasonically mixed to obtain a homogeneous mixture.

[0009] (3) The mixture undergoes a second reaction to obtain an oil well cement retarder.

[0010] The second aspect of this invention provides an application of the oil well cement retarder prepared in the first aspect in the oilfield field.

[0011] Through the above technical solution, the preparation method of an oil well cement retarder and its application provided by the present invention achieve the following beneficial effects:

[0012] The method of this invention is used to prepare an oil well cement retarder, which has excellent stability. The cement slurry prepared with this oil well cement retarder has better thickening time and excellent high temperature resistance (meeting the usage requirements of 160℃). This oil well cement retarder also has the characteristics of inorganic material filling and reinforcement, which greatly improves the mechanical properties of the cement slurry solidified, effectively solving the problem of slow strength development of cement stone under low temperature environment during the top setting period, and can adapt to the large temperature difference requirement of 80℃. Detailed Implementation

[0013] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0014] To achieve the above objectives, the first aspect of this invention provides a method for preparing an oil well cement retarder, the method comprising the following steps:

[0015] (1) The stabilizer, tartaric acid, sodium gluconate, sodium gluconate and water were reacted to obtain the first product;

[0016] (2) The first product is initially mixed with graphene to obtain an initial mixed product, and the initial mixed product is ultrasonically mixed to obtain a homogeneous mixture.

[0017] (3) The mixture undergoes a second reaction to obtain an oil well cement retarder.

[0018] According to the present invention, the conditions for the first reaction include: a temperature of 40-60°C and a time of 0.5-2 hours.

[0019] According to the present invention, the initial mixing method is stirring. Preferably, the stirring conditions include: a rotation speed of 150-180 rpm and a stirring time of 0.5-2 hours.

[0020] According to the present invention, the conditions for ultrasonic mixing include: an ultrasonic frequency of 10-30 kHz and an ultrasonic time of 10-30 min.

[0021] In this invention, ultrasonic mixing is employed, and combined with the specific ultrasonic conditions described above, the interlayer spacing of graphene easily expands under ultrasonic conditions, accelerating the hybridization of organic substances and graphene in the retarder component. This improves the homogeneity of the inorganic-organic material and solves the problem of low stability after hybridization.

[0022] According to the present invention, the conditions for the second reaction include: a temperature of 40-60°C and a time of 10-70 min, preferably 20-40 min.

[0023] In this invention, if the conditions for the second reaction are not properly selected, the efficiency of the inorganic and organic hybridization will decrease, the two materials will become inhomogeneous, precipitation will occur in the reaction system, and although the thickening time of the retarder meets the requirements, the graphene is not evenly dispersed into the cement paste system along with the retarder, and thus cannot play a reinforcing role.

[0024] According to the present invention, the amounts of each substance in the raw materials are as follows: 0.01-2 parts by weight of graphene, 10-30 parts by weight of stabilizer, 5-20 parts by weight of tartaric acid, 2-15 parts by weight of glucoheponic acid, 0.5-10 parts by weight of sodium gluconate, and 100 parts by weight of water.

[0025] According to the present invention, the graphene comprises 0.1-1 parts by weight, the stabilizer comprises 15-20 parts by weight, the tartaric acid comprises 10-15 parts by weight, the sodium gluconate comprises 5-10 parts by weight, the sodium gluconate comprises 1-5 parts by weight, and the water comprises 100 parts by weight.

[0026] According to the present invention, in the preparation of raw materials, the total weight ratio of the stabilizer, the tartaric acid, the sodium gluconate and the sodium gluconate to the graphene is 260-370:1.

[0027] According to the present invention, the weight ratio of graphene to stabilizer is 0.005-0.015:1.

[0028] According to the present invention, the stabilizer is selected from white dextrin and / or yellow dextrin.

[0029] According to the present invention, the graphene has a layer structure of 1-3 layers.

[0030] According to the present invention, the carbon content of the graphene is >98 wt%.

[0031] According to the present invention, the average particle size of the graphene is 7-12 μm.

[0032] This invention provides an application of the oil well cement retarder prepared in the first aspect in the oilfield field. For example, the oil well cement retarder prepared in this invention can be used to prepare cement slurry for cementing.

[0033] In the following embodiments, unless otherwise specified, all raw materials used are commercially available.

[0034] The reinforcing agent is graphene purchased from Shenzhen Hongdachang Evolution Technology Co., Ltd. It has a layered structure with 1-3 layers, a carbon content of >98wt%, and an average particle size of 7-12μm.

[0035] Unless otherwise specified, all raw materials used in the following examples, test cases and comparative test cases are commercially available.

[0036] Water loss reducer: Brand name SCF180L, purchased from Texas Continental Shelf Petroleum Engineering Technology Co., Ltd.

[0037] The following are the test methods for performance parameters involved in this invention:

[0038] (1) Thickening time: The thickening time of cement slurry was tested according to the method recorded in standard GB / T19139-2015. Combined with the application conditions on site, the experimental conditions were set as follows: 160℃×80min×80MPa.

[0039] (2) Compressive strength: The compressive strength of the cement grout was tested according to the method described in standard GB / T19139-2015. To meet the application conditions of 80℃ temperature difference, the experimental conditions were set as follows: 80℃×80min×80MPa.

[0040] (3) Stability: The stability of the retarder was tested according to the method described in SY / T5504.1-2013, and observed at room temperature, normal pressure, in a closed transparent container.

[0041] Example 1

[0042] (1) 18 parts by weight of white dextrin, 14.4 parts by weight of tartaric acid, 7.2 parts by weight of sodium gluconate and 3.6 parts by weight of sodium gluconate were added to 100 parts by weight of water to carry out the first reaction. The conditions for the first reaction were: temperature 50℃ and time 1h to obtain the first product.

[0043] (2) The first product was stirred with 0.14 parts by weight of graphene under the following conditions: 160 rpm for 1 h to obtain a preliminary mixture. The preliminary mixture was then ultrasonically mixed at a frequency of 20 kHz for 30 min to obtain a homogeneous mixture.

[0044] (3) The mixture undergoes a second reaction, the conditions of which are: temperature 50℃ and time 20min, to obtain oil well cement retarder.

[0045] Examples 2-6 and the comparative examples were prepared according to the method of Example 1. The types, amounts, and specific preparation conditions of each material used in Examples 2-6 and the comparative examples are shown in Table 1. Oil well cement retarders A2-A6 and D1 (the comparative example is represented by D) were obtained.

[0046] Table 1

[0047]

[0048]

[0049] Note: The amounts of each component in the table are by weight.

[0050] Test case

[0051] Oil well cement slurry systems were prepared using the oil well cement retarder from Examples 1-6 and Comparative Example 1, respectively. The test results are shown in Table 2.

[0052] Specifically, the oil well cement slurry system consists of: Grade G cement (100 parts by weight), silica fume (35 parts by weight), fluid loss reducer (5 parts by weight), retarder (1.5 parts by weight), and water (53 parts by weight).

[0053] The retarder is the oil well cement retarder prepared in Examples 1-6, and the corresponding test designations are denoted as C1-C6. The test designation of Comparative Example 1 is denoted as DC1.

[0054] Comparative Test Example 2

[0055] The oil well cement slurry system consists of: Grade G cement (100 parts by weight), silica fume (35 parts by weight), fluid loss reducer (5 parts by weight), retarder (0 parts by weight), and water (53 parts by weight), with the test designation DC2.

[0056] Comparative Test Case 3

[0057] The oil well cement slurry system consists of: Grade G cement (100 parts by weight), silica fume (35 parts by weight), fluid loss reducer (5 parts by weight), retarder (1.5 parts by weight, purchased from Texas Continental Shelf Petroleum Engineering Technology Co., Ltd., brand name SCR-180L), and water (53 parts by weight). The test designation is DC3.

[0058] Table 2

[0059] Test case stability Thickening time (min) Compressive strength (MPa) C1 good 303 24.5 C2 good 335 20.7 C3 Substances precipitate on the surface 274 33.6 C4 good 305 25.1 C5 Layered, with slight sediment at the bottom. 198 15.2 C6 Layered, with sediment at the bottom. 175 36.5 DC1 Layered, with sediment at the bottom. 165 13.3 DC2 good 120 12.3 DC3 Layered, with sediment at the bottom. 315 18.1

[0060] As shown in Table 2, by employing the technical solution of this invention, and by adjusting the proportions of each component and combining it with the specific preparation method described in this invention, the organic and inorganic materials in the components can be effectively combined. Through the synergistic effect between the components, the problem of poor stability of hybrid products caused by excessive specific surface area and adsorption of inorganic materials can be avoided, while effectively improving the strength of the cement-cured product. Furthermore, by combining the specific preparation method described in this invention with ultrasonic dispersion and adjusting the preparation parameters, the thickening time and compressive strength of the corresponding materials are significantly improved.

[0061] For example, the oil well cement retarder prepared in Examples 1, 2, and 4 of this invention yielded C1, C2, and C4 results after testing, respectively. Table 2 clearly shows that the oil well cement retarder prepared in these examples not only exhibits excellent stability but also has a thickening time greater than 300 min and a compressive strength of more than 20 MPa for the solidified cement. These parameters are significantly superior to those of samples tested in other test examples and comparative examples. The sample prepared in Example 3 had a thickening time of 274 min and a compressive strength of 33.6 MPa for the solidified cement. Although some material precipitated on the surface during the stability test, this did not affect its use in certain application scenarios. Example 3 uses a high-temperature resistant retarder used in the art. Comparative performance shows that by adjusting the formulation of this invention, the stability and compressive strength of the retarder prepared in this application are significantly better than existing products.

[0062] The oil well cement retarder prepared in Examples 5 and 6 were tested and the corresponding results were C5 and C6, respectively. Compared with the oil well cement retarder prepared in Examples 1-4, the overall performance was slightly reduced. After adjusting the preparation process, the thickening time and compressive strength of the cement solidified product were better than those of Comparative Test Example 1 and Comparative Test Example 2.

[0063] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing an oil well cement retarder, the method comprising the following steps: (1) The stabilizer, tartaric acid, sodium gluconate, sodium gluconate and water are reacted in the first reaction to obtain the first product; The stabilizer is selected from white dextrin; the conditions for the first reaction include: a temperature of 40-60℃ and a time of 0.5-2h; (2) The first product is initially mixed with graphene to obtain an initial mixed product, and the initial mixed product is ultrasonically mixed to obtain a homogeneous mixture; the ultrasonic mixing conditions include: ultrasonic frequency of 10-30kHz, ultrasonic time of 10-30min; the graphene has a layer structure of 1-3 layers; the average particle size of the graphene is 7-12μm. (3) The mixture undergoes a second reaction to obtain an oil well cement retarder; the conditions for the second reaction include: a temperature of 40-60℃ and a time of 10-70 min; The composition includes 0.01-2 parts by weight of graphene, 10-30 parts by weight of stabilizer, 5-20 parts by weight of tartaric acid, 2-15 parts by weight of glucoheponic acid, 0.5-10 parts by weight of sodium gluconate, and 100 parts by weight of water.

2. The preparation method according to claim 1, wherein, The initial mixing method is stirring.

3. The preparation method according to claim 2, wherein, The stirring conditions include: a rotation speed of 150-180 rpm and a stirring time of 0.5-2 h.

4. The preparation method according to claim 1, wherein, The conditions for the second reaction include a time of 20-40 minutes.

5. The preparation method according to claim 1, wherein, The graphene is 0.1-1 parts by weight, the stabilizer is 15-20 parts by weight, the tartaric acid is 10-15 parts by weight, the sodium gluconate is 5-10 parts by weight, the sodium gluconate is 1-5 parts by weight, and the water is 100 parts by weight.

6. The preparation method according to claim 5, wherein, In the preparation raw materials, the total weight ratio of the stabilizer, the tartaric acid, the sodium gluconate and the sodium gluconate to the graphene is 260-370:

1.

7. The preparation method according to claim 6, wherein, The weight ratio of graphene to stabilizer is 0.005-0.015:

1.

8. The preparation method according to claim 1, wherein, The carbon content of the graphene is >98wt%.

9. The application of the oil well cement retarder prepared by the method of any one of claims 1-8 in the oilfield field.

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