High-efficiency film-forming plugging agent for drilling fluid and preparation method thereof

Abstract

The application provides a high-efficiency film-forming plugging agent for drilling fluid and a preparation method thereof, and belongs to the technical field of oil and gas drilling. The high-efficiency film-forming plugging agent for drilling fluid is mainly prepared from the following raw materials in parts by weight: 50-60 parts of an organic silicon solvent, 80-100 parts of an ethanol aqueous solution, 10-15 parts of polyurethane particles and 10-15 parts of nano silicon dioxide. The high-efficiency film-forming plugging agent obtained by the application has little influence on the performance of drilling fluid, is beneficial to reducing the filtration loss of drilling fluid, is beneficial to improving the stability of drilling fluid, and has good salt resistance and temperature resistance.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of oil and gas drilling, and particularly relates to a high-efficiency film-forming plugging agent for drilling fluid and a preparation method thereof. BACKGROUND

[0002] At present, most drilling fluid additives have relatively single performance. With the development of drilling technology, the oil and gas development area is continuously widened, the drilling and development are gradually developed from shallow layer to deep layer, the drilling depth is continuously increased, the geological structure is increasingly complex, and the technical requirements for drilling fluid are increasingly high for special technology well drilling such as high-inclination horizontal well, radial horizontal well, and small-hole well sidetracking horizontal well. The drilling fluid additive with single performance is increasingly difficult to meet the demand of modern drilling. It is urgent to develop a new multifunctional drilling fluid additive to meet the requirements of oil and gas exploitation.

[0003] The plugging agent is a kind of treatment agent with a large amount in drilling fluid, which has the functions of adjusting the dynamic shear force, static shear force, filter loss of drilling fluid and improving the quality of mud cake, thereby having important influence on wellbore stability and oil layer protection. The research on drilling fluid anti-sloughing technology shows that the plugging agent for drilling fluid must meet the following conditions to play a role in plugging and anti-sloughing:

[0004] (1) The thermal stability of the plugging agent under high temperature condition is also a crucial factor. The product with poor thermal stability is easy to cause the performance of drilling fluid to rise and fall greatly, which is difficult to control.

[0005] (2) The thickening effect of the plugging agent before and after high-temperature action should not have a large difference. After high-temperature action, the plugging agent should not produce flocculation phenomenon, but should have good dispersion and deflocculation effect, so as to control the drilling fluid from high-temperature thickening, improve the stability of the drilling fluid and maintain its good plugging and filter loss reduction performance.

[0006] (3) The plugging agent should have strong high-temperature resistance and hydration capacity, so as to improve the efficiency of deformable colloidal adhesion, filling and plugging filter loss channel in the filter cake under high-temperature condition, form a thin and tough dense mud cake, improve the flow resistance of filtrate and reduce the filter loss of drilling fluid.

[0007] (4) The plugging agent should have strong inhibition and lubricity as far as possible, and should have good compatibility with each other, so as to improve the "synergistic effect" under high-temperature condition.

[0008] (5) The plugging agent should also be easy to dissolve or disperse, so as to facilitate on-site use, maintenance and response to various emergencies.

[0009] Therefore, development of a high-efficiency film-forming plugging agent for drilling fluid will provide new technical support for solving the problem of well wall stability plugging and collapse prevention in oil and gas drilling, and has important significance for further reducing the complex situation of well collapse, ensuring the safety of oil and gas drilling underground, and accelerating the exploration and development process of oil and gas resources. SUMMARY

[0010] The high-efficiency film-forming plugging agent prepared by the application solves the problems of poor thermal stability, strong tackifying effect, poor inhibition, poor lubricity and unsatisfactory plugging effect on shale micro-crack formation of conventional plugging materials; the high-efficiency film-forming plugging agent has little influence on the performance of drilling fluid, is conducive to reducing the filtration loss of drilling fluid, and is conducive to improving the stability of drilling fluid, and has good temperature resistance.

[0011] One of the purposes of the application is to provide a high-efficiency film-forming plugging agent for drilling fluid.

[0012] The second purpose of the application is to provide a preparation method of the high-efficiency film-forming plugging agent for drilling fluid.

[0013] In order to achieve the above-mentioned purposes of the application, the following technical solutions are adopted:

[0014] In the first aspect, the application provides a high-efficiency film-forming plugging agent for drilling fluid, which is mainly prepared from the following raw materials in parts by weight: 50-60 parts of silicone solvent, 80-100 parts of ethanol aqueous solution, 10-15 parts of polyurethane particles and 10-15 parts of nano-silicon dioxide.

[0015] The silicone solvent can be at least one selected from 3-aminopropyl triethoxysilane and 3-aminopropyl trimethoxysilane.

[0016] The parts by weight of the silicone solvent are 50, 52, 54, 56, 58 and 60, but are not limited thereto.

[0017] The mass percentage concentration of ethanol in the ethanol aqueous solution is 50%.

[0018] The parts by weight of the ethanol aqueous solution are, for example, 80, 82, 85, 86, 88, 90, 92, 95, 96, 98 and 100, but are not limited thereto.

[0019] The polyurethane particles can be commercially available polyurethane resin particles with a particle size of 0.1-1 mm.

[0020] The parts by weight of the polyurethane particles are, for example, 10, 11, 12, 13, 14 and 15, but are not limited thereto.

[0021] The nano-silicon dioxide has a particle size of 10-50 nm and a specific surface area of >250 m 2 / g.

[0022] The weight fraction of the nanosilica is, for example, 10, 11, 12, 13, 14, 15 parts, but is not limited thereto.

[0023] In a second aspect, the present application provides a preparation method of the high-efficiency film-forming plugging agent for drilling fluid, comprising the following steps:

[0024] The nanosilica and the polyurethane particles are first mixed at a first temperature, and then the silicone solvent and the ethanol aqueous solution are added dropwise at a second temperature for reaction, the pH value of the system is adjusted to 7-8, the reaction is continuously kept warm, and the system is cooled to room temperature to obtain the high-efficiency film-forming plugging agent for drilling fluid.

[0025] In some embodiments, the first temperature is 60-70°C, and the second temperature is 80-90°C.

[0026] In some embodiments, the reaction is kept constant at the second temperature for 1-2 h, and the reaction is continuously kept warm for 1-2 h.

[0027] In a specific embodiment, the preparation method of the high-efficiency film-forming plugging agent for drilling fluid comprises the following steps:

[0028] According to the preparation method of the high-efficiency film-forming plugging agent for drilling fluid, the components are weighed and mixed as follows: Figure 1 The synthesis device for assembling the plugging agent is assembled, and the synthesis device is composed of an electric stirrer, a condenser, two 100-ml constant-pressure dropping funnels, a 500-ml ground-mouth four-necked flask, a water bath, and a thermometer.

[0029] The components, i.e., the silicone solvent, the ethanol aqueous solution, the polyurethane particles, and the nanosilica, are weighed and mixed respectively, the nanosilica is added to the four-necked flask, the components, i.e., the silicone solvent and the ethanol aqueous solution, are added to the two constant-pressure dropping funnels, the stirring speed is set to 300-320 r / min, and heating is started, when the temperature is constant at 60°C, the polyurethane particles are added, stirring is performed for 10 min, heating is continuously performed, when the temperature is increased to 80°C and constant, the uniform-speed dropping of the silicone solvent and the ethanol aqueous solution is started, and the dropping speed is controlled to be within the range of 20-40 drops / min; after the dropping is completed, the reaction is continuously performed for 1-2 h at a constant temperature, the pH value of the system is adjusted to 7-8 with ammonia water, the system is continuously kept warm for 1-2 h, the system is cooled to room temperature, and the product is discharged, to obtain the blue-light-emitting emulsion, the emulsion is dried at 100±3°C, and the solid content of the emulsion is about 20-30%.

[0030] Beneficial effects:

[0031] The high-efficiency film-forming plugging agent for drilling fluid contains micro-nano deformable cementable film-forming particles, which can effectively improve the particle size distribution in the drilling fluid system, form a gel film on the surface of the stratum rock, effectively prevent free water from penetrating into the rock interlaminar space, and prevent shale hydration. Meanwhile, the flexible gel film can be inlaid between the micro-crack gaps to prevent the propagation of rock stress and prevent wellbore collapse. In addition, after interacting with clay particles, barite particles and other high molecular polymers in the drilling fluid and filtering and gelling, a three-dimensional polymer network structure is formed in the mud cake, which can effectively play a role of reinforcing bars and bridges, so that the toughness and strength of the mud cake are obviously improved. The product has good compatibility with other treatment agents, and the temperature resistance can reach 150 DEG C. Especially in fresh water-based polymer drilling fluid, due to the good film-forming effect, the clay particle hydration and dispersion can be inhibited, so it also has certain inhibition and viscosity reduction effect. The treatment agent is compatible with other treatment agents, and can be used in various water-based drilling fluid systems of production wells and exploration wells, especially for hard and brittle shale, broken and micro-crack developed stratum, which has significant flexible plugging effect, film-forming inhibition effect and effective wellbore protection.

[0032] The application has been described in detail above, but the above-mentioned embodiments are only illustrative in nature and are not intended to limit the application. In addition, the present application is not limited by any theory described in the foregoing prior art or summary of the application or in the following examples. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 Synthesis device of high-efficiency film-forming plugging agent.

[0034] Figure 2 Filter loss and time relationship curve of different plugging agent systems.

[0035] Figure 3 TG curve of high-efficiency film-forming plugging agent. DETAILED DESCRIPTION

[0036] The application will be further described below in conjunction with examples, and it should be noted that the following examples are provided only for illustrative purposes and do not constitute a limitation on the scope of protection of the application.

[0037] Unless otherwise specified, the raw materials, reagents, methods and the like used in the examples are conventional raw materials, reagents and methods in the art.

[0038] The organic silicon solvent is from Shandong Xindongli Chemical Co., Ltd.;

[0039] The polyurethane particles (about 0.25 mm) are from Wanhua Chemical Group Co., Ltd., WHT-1198;

[0040] Nanosilica from Nanjing Bokete New Material Co., Ltd., PST-H20.

[0041] Example 1

[0042] A high-efficiency film-forming plugging agent for drilling fluid is prepared from the following raw materials in parts by weight: 50 parts of silicone solvent, 100 parts of aqueous ethanol solution (ethanol concentration 50%), 10 parts of polyurethane particles, and 10 parts of nanosilica.

[0043] Preparation method:

[0044] The components, i.e., silicone solvent, aqueous ethanol solution, polyurethane particles, and nanosilica, are weighed and mixed separately. The nanosilica is added to a four-necked flask, and the silicone solvent and aqueous ethanol solution are added to two constant-pressure dropping funnels. The stirring speed is set to 300 r / min, and heating is started. When the temperature is constant at 60℃, the polyurethane particles are added, and stirring is continued for 10 min. Heating is continued, and when the temperature rises to 80℃ and is constant, the silicone solvent and aqueous ethanol solution are added at a uniform speed, with the dropping speed controlled within 30 drops / min. After the addition is completed, the reaction is continued at a constant temperature for 1-2 h. The pH value of the system is adjusted to 7-8 with ammonia water, and the temperature is maintained for another 1-2 h. The mixture is cooled to room temperature, and the product, a blue light-emitting emulsion, is obtained. The emulsion is dried at 100±3℃, and the solid content of the emulsion is about 25%.

[0045] Example 2

[0046] A high-efficiency film-forming plugging agent for drilling fluid is prepared from the following raw materials in parts by weight: 55 parts of silicone solvent, 80 parts of aqueous ethanol solution (ethanol concentration 50%), 12 parts of polyurethane particles, and 14 parts of nanosilica.

[0047] The preparation method is as described in Example 1.

[0048] Example 3

[0049] A high-efficiency film-forming plugging agent for drilling fluid is prepared from the following raw materials in parts by weight: 60 parts of silicone solvent, 90 parts of aqueous ethanol solution (ethanol concentration 50%), 10 parts of polyurethane particles, and 12 parts of nanosilica.

[0050] The preparation method is as described in Example 1.

[0051] Comparative Example 1

[0052] The difference from Example 1 is that the aqueous ethanol solution is replaced by polymeric polyol.

[0053] Performance evaluation:

[0054] Evaluation of plugging performance in Test Example 1

[0055] The plugging performances of the high-efficiency film-forming plugging agent (Example 1, referred to as GWHPPG), plugging agent sulfonated asphalt FT-1A and plugging agent MAX-SHIELD were analyzed based on high-temperature filtration experiments. The base slurry formula used in the experiments is: 2% bentonite (400 ml) + 0.2% xanthan gum XC + 0.8% polyanionic cellulose PAC_LV + 135 g barite. Since the temperature resistance of the filter medium, i.e. the microporous filter membrane, is less than 100°C, the temperature of the high-temperature and high-pressure filtration experiment is set to 85°C. From the experimental results, it can be seen that the plugging effect of the high-efficiency film-forming plugging agent is basically equivalent to that of the MAX-SHIELD plugging agent, and is better than that of the FT-1A plugging agent. Figure 2 The experimental results show that the plugging effect of the high-efficiency film-forming plugging agent is basically equivalent to that of the MAX-SHIELD plugging agent, and is better than that of the FT-1A plugging agent.

[0056] Effect of rheological property and filtration property

[0057] The drilling fluids were prepared by adding different contents of the high-efficiency film-forming plugging agent (Example 1) and the plugging agent of Comparative Example 1 into the base slurry, respectively, to test the effect of the plugging agent on the rheological property and filtration property of the drilling fluid. The experimental results are shown in Tables 1 and 2.

[0058] Table 1: Effect of plugging agent on viscosity and yield value (before aging)

[0059]

[0060] Table 2: Effect of plugging agent on viscosity and yield value (after aging)

[0061]

[0062] Note: 1. Base slurry: 2% bentonite (400 ml) + 0.2% XC + 0.8% PAC_LV + 135 g barite

[0063] 2. Aging temperature: 85°C.

[0064] From the experimental results, it can be seen that before and after aging, the addition of different contents of the high-efficiency film-forming plugging agent has little effect on the rheological property of the drilling fluid, and reduces the filtration volume. It can be seen that the high-efficiency film-forming plugging agent does not increase the viscosity, and has a decreasing trend in the filtration volume, which meets the general requirements of high-density drilling fluid for plugging agents. The effect of the plugging agent of Comparative Example 1 is not as good as that of the present application.

[0065] Evaluation of salt resistance

[0066] In view of the fact that the water in Sichuan shale formation may contain calcium, and a certain concentration of KCl needs to be added in the water-based drilling fluid system to maintain sufficient inhibition, 5% of the high-efficiency film-forming plugging agent (Example 1), the plugging agent of Comparative Example 1 and different contents of KCl and CaCl2 were added to the base slurry to prepare salt water drilling fluids of different concentrations, to test the salt resistance and calcium resistance. The experimental results are shown in Tables 3 and 4.

[0067] Table 3 Evaluation of the salt resistance of the plugging agent (before aging)

[0068]

[0069] Table 4 Evaluation of the salt resistance of the plugging agent (after aging)

[0070]

[0071] Notes: 1. Base slurry: 0.2% XC + 0.8% PAC_LV + 0.2% PAC_HV + 0.5% green starch + 135g barite

[0072] 2. Aging temperature: 85℃

[0073] The experimental results show that the addition of the highly efficient film-forming plugging agent significantly reduced the filtration loss of the system, while the addition of KCl even slightly reduced the filtration loss. When the system was simultaneously contaminated with 15% KCl and different concentrations of CaCl2, the viscosity-shear force showed a slight increase, while the filtration loss only increased slightly, without showing a significant trend. Therefore, the highly efficient film-forming plugging agent can resist both 15% KCl and 2% CaCl2, exhibiting good resistance to salt and calcium, and is suitable for shale gas water-based drilling fluid systems. The salt resistance of Comparative Example 1 is not as good as that of this invention.

[0074] Test Example 4: Evaluation of Temperature Resistance

[0075] The TG curve of the high-efficiency film-forming plugging agent is shown below. Figure 3 .Depend on Figure 3 It can be seen that the thermal decomposition of the high-efficiency film-forming plugging agent in argon can be divided into the following stages: the thermal weight loss before 300℃ is due to the removal of free water and bound water in the high-efficiency film-forming plugging agent, that is, the removal of adsorbed water. When the temperature is 340~450℃, the main component of the high-efficiency film-forming plugging agent decomposes. The strong exothermic peak at 427.6℃ corresponds to the weight loss of the main component of the high-efficiency film-forming plugging agent, indicating that the main component of the high-efficiency film-forming plugging agent decomposes at this point. The initial decomposition temperature is around 340℃. The strong exothermic peak indicates that the main component of the high-efficiency film-forming plugging agent will rapidly fail after being exposed to an ambient temperature of 340℃. On the other hand, the TG results show that when the temperature does not exceed 340℃, at least about 74% (w) of the high-efficiency film-forming plugging agent does not decompose, indicating that the high-efficiency film-forming plugging agent has good thermal stability.

[0076] The above embodiments are only used to illustrate the technical solutions of the present application, but not limit the present application. Although the present application is described in detail with reference to the above embodiments, it should be understood by those skilled in the art that the technical solutions recorded in the above embodiments can be modified, or some or all of the technical features can be replaced equivalently without departing from the spirit and essence of the present application defined in the claims of the present application.

Claims

1. A high-efficiency film-forming and plugging agent for drilling fluids, characterized in that, It is mainly prepared from the following raw materials in parts by weight: 50-60 parts of organosilicon solvent, 80-100 parts of ethanol aqueous solution, 10-15 parts of polyurethane particles and 10-15 parts of nano-silica. The ethanol aqueous solution contains 40-60% ethanol by mass percentage. The preparation method of the high-efficiency film-forming plugging agent for drilling fluid includes the following steps: First, nano-silica and polyurethane particles are mixed at a first temperature. Then, organosilicon solvent and ethanol aqueous solution are added dropwise at a second temperature for a constant-temperature reaction. The pH value of the system is adjusted to 7-8, and the reaction is continued at the same temperature. After cooling to room temperature, a high-efficiency film-forming and plugging agent for drilling fluid is obtained. The first temperature is 60-70℃ and the second temperature is 80-90℃.

2. The high-efficiency film-forming and plugging agent for drilling fluid according to claim 1, characterized in that, The organosilicon solvent is at least one selected from 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane.

3. The high-efficiency film-forming and plugging agent for drilling fluid according to claim 1, characterized in that, The particle size of polyurethane particles is 0.1-1 mm.

4. The high-efficiency film-forming and plugging agent for drilling fluid according to claim 1, characterized in that, Nano-silica has a particle size of 10-50 nm and a specific surface area >250 m². 2 / g.

5. The high-efficiency film-forming plugging agent for drilling fluid according to claim 1, characterized in that, In the preparation method, the reaction is carried out at a constant temperature for 1-2 hours at the second temperature, and then the reaction is continued at the temperature for another 1-2 hours.

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