Efficient film-forming plugging agent for drilling fluid and preparation method of efficient film-forming plugging agent

Abstract

The invention provides an efficient film-forming plugging agent for drilling fluid and a preparation method of the efficient film-forming plugging agent, and belongs to the technical field of petroleum and natural gas drilling. The efficient film-forming blocking agent for the 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 water solution, 10-15 parts of polyurethane particles and 10-15 parts of nano silicon dioxide. The obtained efficient film-forming plugging agent has small influence on the performance of the drilling fluid, is beneficial to reducing the filter loss of the drilling fluid, is beneficial to improving the stability of the drilling fluid, and has good salt resistance and temperature resistance.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and natural gas drilling, and in particular relates to a high-efficiency film-forming plugging agent for drilling fluid and a preparation method thereof. Background Art

[0002] At present, most drilling fluid additives have relatively simple properties. With the development of drilling technology, the oil and gas development area is constantly expanding, drilling and development is gradually developing from shallow to deep, the drilling depth is constantly increasing, the geological structure is becoming more and more complex, and the drilling of special process wells such as high-angle horizontal wells, radial horizontal wells, small-hole sidetracking horizontal wells, etc., has higher and higher technical requirements for drilling fluids. Drilling fluid additives with single performance are increasingly difficult to meet the needs of modern drilling. In order to meet the requirements of oil and gas extraction, the development of new multifunctional drilling fluid additives is urgently needed.

[0003] Plugging agents are a type of treatment agent used in large quantities in drilling fluids. In addition to their plugging effects, they also have the functions of adjusting the dynamic shear force, static shear force, filtration rate and improving the quality of mud cakes, thus having an important impact on wellbore stability and oil layer protection. Research on drilling fluid anti-collapse technology shows that plugging agents used in drilling fluids must meet the following conditions to play a plugging and anti-collapse role:

[0004] (1) The thermal stability of plugging agents under high temperature conditions is also a crucial factor. Products with poor thermal stability can easily lead to large fluctuations in drilling fluid performance and are difficult to control;

[0005] (2) The viscosity-increasing effect of the plugging agent before and after high temperature should not be too different. After high temperature, no flocculation should occur, but it should have good dispersion and deflocculation effects, so as to control the drilling fluid from high temperature thickening, improve the stability of the drilling fluid and maintain its good plugging and filtration reduction performance;

[0006] (3) The plugging agent should have strong high temperature resistant adsorption and hydration capabilities to improve the efficiency of the deformable colloid in the filter cake to adhere, fill and plug the filtration loss channel under high temperature conditions, form a thin and tough dense mud cake, increase the filtrate flow resistance, and reduce the drilling fluid loss;

[0007] (4) They should have strong inhibitory and lubricating properties, and should have good compatibility with each other to enhance their "synergistic effect" under high temperature conditions;

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

[0009] Therefore, the development of an efficient film-forming plugging agent for drilling fluid will provide new technical support for solving the problem of stable sealing and anti-collapse of oil and gas drilling well walls, which is of great significance for further reducing the complexity of well collapse, ensuring the safety of oil and gas drilling underground, and accelerating the exploration and development of oil and gas resources. Summary of the invention

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

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

[0012] The second object of the present invention is to provide a method for preparing a high-efficiency film-forming plugging agent for drilling fluid.

[0013] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0014] In a first aspect, the present invention 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 organic silicon solvent, 80-100 parts of ethanol aqueous solution, 10-15 parts of polyurethane particles and 10-15 parts of nano-silicon dioxide.

[0015] The organic silicon solvent may be at least one selected from 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane.

[0016] The weight proportion of the organic silicon solvent is 50, 52, 54, 56, 58, or 60 parts, but is not limited thereto.

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

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

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

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

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

[0022] The weight percentage of nano-silicon dioxide is, for example, 10, 11, 12, 13, 14, or 15 parts, but is not limited thereto.

[0023] In a second aspect, the present invention provides a method for preparing the above-mentioned high-efficiency film-forming plugging agent for drilling fluid, comprising the following steps:

[0024] First, nano silicon dioxide and polyurethane particles are mixed at a first temperature, then silicone solvent and 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 continued at a heat preservation temperature, and the reaction is cooled to room temperature to obtain a 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 carried out at the second temperature for 1 to 2 hours, and the reaction is continued at the second temperature for 1 to 2 hours.

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

[0028] according to Figure 1 Assemble a synthetic device for the plugging agent, which consists 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 of organic silicon solvent, ethanol aqueous solution, polyurethane particles and nano-silica are weighed and mixed according to the design, the nano-silica is added into a four-necked flask, the components of organic silicon solvent and ethanol aqueous solution are added into two constant pressure dropping funnels respectively, 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, stirred for 10 minutes, and heating is continued. When the temperature rises to 80°C and is constant, the organic silicon solvent and ethanol aqueous solution are uniformly added dropwise, and the dropping speed is controlled within the range of 20-40 drops / min. After the dropping is completed, the reaction is continued at a constant temperature for 1-2 hours, the pH value of the system is adjusted to 7-8 with ammonia water, and the temperature is kept warm for 1-2 hours. The material is cooled to room temperature and discharged to obtain a blue-light emulsion, and the solid content of the emulsion is about 20-30% after drying at 100±3°C and weighing.

[0030] Beneficial effects:

[0031] The high-efficiency film-forming plugging agent for drilling fluid of the present invention contains micro-nano deformable and cementable film-forming particles, which can not only effectively improve the particle gradation in the drilling fluid system, but also form a film on the surface of the formation rock, effectively preventing free water from penetrating into the rock layer spacing and preventing the hydration of shale. At the same time, the flexible film can also be embedded in the gaps between microcracks to prevent the propagation of rock stress and prevent the collapse of the well wall. In addition, after interacting with clay particles, barite particles, and other high molecular polymers in the drilling fluid, the three-dimensional polymer network structure is formed inside the mud cake after filtration and gelation, which can effectively play the role of bridging and bridging, so that the toughness and strength of the mud cake are significantly improved. The product has good compatibility with other treatment agents and can resist temperatures up to 150°C. Especially in freshwater-based polymer drilling fluids, it has a good film-forming effect and can inhibit the hydration and dispersion of clay particles, so it also has a certain inhibitory and viscosity-reducing effect. This treatment agent works well with other treatment agents and can be used in various water-based drilling fluid systems for production wells and exploration wells. It is especially suitable for hard and brittle shales, broken and micro-cracked formations. It has significant flexible plugging effect and film formation inhibition effect, and can effectively protect the well wall.

[0032] The present invention has been described in detail above, but the above embodiments are only illustrative in nature and are not intended to limit the present invention. In addition, this article is not limited by any theory described in the above prior art or invention content or the following examples. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a synthesis device for highly efficient film-forming plugging agents.

[0034] Figure 2 This is the relationship curve between the filtration loss and time of systems containing different plugging agents.

[0035] Figure 3 This is the TG curve of the highly efficient film-forming plugging agent. DETAILED DESCRIPTION

[0036] The present invention is further described below in conjunction with examples. It should be noted that the following examples are provided for illustrative purposes only and do not constitute a limitation on the scope of protection claimed for the present invention.

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

[0038] The organosilicon solvent was from Shandong New Kinetic Energy Chemical Co., Ltd.;

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

[0040] Nano-silicon dioxide was from Nanjing Baoket New Materials 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 organic silicon solvent, 100 parts of ethanol aqueous solution (ethanol concentration 50%), 10 parts of polyurethane particles and 10 parts of nano silicon dioxide.

[0043] Preparation method:

[0044] The components of organosilicon solvent, ethanol aqueous solution, polyurethane particles and nano-silica were weighed and mixed according to the design, the nano-silica was added into a four-necked flask, and the components of organosilicon solvent and polymer polyol were added into two constant pressure dropping funnels respectively, the stirring speed was set to 300r / min, and heating was started. When the temperature was constant at 60°C, the polyurethane particles were added, stirred for 10min, and heating was continued. When the temperature rose to 80°C and was constant, the organosilicon solvent and polymer polyol were uniformly added dropwise, and the dropping speed was controlled within the range of 30 drops / min. After the addition was completed, the reaction was continued at a constant temperature for 1-2h, the pH value of the system was adjusted to 7-8 with ammonia water, and the heat preservation was continued for 1-2h. The material was cooled to room temperature and discharged to obtain a blue-light emulsion. The solid content of the emulsion was about 25% after drying at 100±3°C and weighing.

[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 organic silicon solvent, 80 parts of ethanol aqueous solution (ethanol concentration 50%), 12 parts of polyurethane particles and 14 parts of nano silicon dioxide.

[0047] The preparation method is as 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 organic silicon solvent, 90 parts of ethanol aqueous solution (ethanol concentration 50%), 10 parts of polyurethane particles and 12 parts of nano silicon dioxide.

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

[0051] Comparative Example 1

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

[0053] Performance evaluation:

[0054] Test Example 1: Evaluation of plugging performance

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

[0056] Experimental Example 2 Effect on Rheology and Fluid Loss

[0057] Different contents of the high-efficiency film-forming plugging agent (Example 1) and the plugging agent of Comparative Example 1 were added to the base slurry to prepare drilling fluids, and the effects of the plugging agents on the rheology and filtration of the drilling fluids were tested. The experimental results are shown in Tables 1 and 2.

[0058] Table 1 Evaluation of the effect of plugging agent on adhesion and shear strength (before aging)

[0059]

[0060]

[0061] Table 2 Evaluation of the effect of plugging agent on adhesion and shear strength (after aging)

[0062]

[0063] Note: 1. Base slurry: 2% bentonite (400ml) + 0.2% XC + 0.8% PAC_LV + 135g barite

[0064] 2. Aging temperature: 85℃.

[0065] From the experimental results, it can be seen that before and after aging, adding different amounts of high-efficiency film-forming plugging agents has little effect on the rheology of the drilling fluid and reduces the filtration loss. It can be seen that the high-efficiency film-forming plugging agent does not increase viscosity and has a tendency to reduce the filtration loss, which meets the general requirements of high-density drilling fluid for plugging agents. However, the plugging agent in Comparative Example 1 is not as effective as the present invention.

[0066] Test Example 3 Evaluation of salt resistance

[0067] In view of the fact that Sichuan shale formation water may contain calcium and a certain concentration of KCl needs to be added to the water-based drilling fluid system to maintain sufficient inhibition of the system, 5% 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, and brine drilling fluids of different concentrations were prepared to test their salt and calcium resistance. The experimental results are shown in Tables 3 and 4.

[0068] Table 3 Evaluation of plugging agent salt resistance (before aging)

[0069]

[0070] Table 4 Evaluation of salt resistance of plugging agent (after aging)

[0071]

[0072]

[0073] Note: 1. Base slurry: 0.2% XC + 0.8% PAC_LV + 0.2% PAC_HV + 0.5% green starch + 135g barite

[0074] 2. Aging temperature: 85℃

[0075] From the experimental results, it can be seen that the addition of efficient film-forming plugging agent significantly reduces the system's filtration loss, and the addition of KCl even slightly reduces the system's filtration loss. When 15% KCl and different concentrations of CaCl2 are simultaneously contaminated in the system, the adhesion and shear force slightly increases, while the filtration loss only slightly increases, but does not show an obvious trend change. It can be seen that the efficient film-forming plugging agent can resist 15% KCl and 2% CaCl2 at the same time, has good salt and calcium resistance, and can adapt to shale gas water-based drilling fluid systems. The salt resistance effect of comparative example 1 is not as good as that of the present invention.

[0076] Test Example 4 Evaluation of Temperature Resistance

[0077] The TG curve of the high-efficiency film-forming plugging agent is shown in Figure 3 .Depend on Figure 3It 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°C 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°C, the main component of the high-efficiency film-forming plugging agent decomposes, and the strong exothermic peak of 427.6°C 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 here, and the initial decomposition temperature is about 340°C. The strong exothermic peak indicates that the main component of the high-efficiency film-forming plugging agent will quickly fail after the action of the 340°C ambient temperature. On the other hand, the TG results show that when the temperature does not exceed 340°C, at least about 74% (w) of the high-efficiency film-forming plugging agent is not decomposed, indicating that the high-efficiency film-forming plugging agent has good thermal stability.

[0078] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some or all of the technical features thereof may be replaced by equivalents, without departing from the spirit and essence of the claims of the present invention; and these modifications or replacements are still within the scope defined by the claims of the present invention.

Claims

1. A high-efficiency film-forming plugging agent for drilling fluid, characterized in that: The invention is mainly prepared from the following raw materials in parts by weight: 50-60 parts of organic silicon solvent, 80-100 parts of ethanol aqueous solution, 10-15 parts of polyurethane particles and 10-15 parts of nano silicon dioxide.

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

3. The high-efficiency film-forming plugging agent for drilling fluid according to claim 1, characterized in that: The mass percentage concentration of ethanol in the ethanol aqueous solution is 40-60%.

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

5. The high-efficiency film-forming plugging agent for drilling fluid according to claim 1, characterized in that: The particle size of nano-silicon dioxide is 10-50nm, and the specific surface area is >250m 2 / g.

6. A method for preparing a high-efficiency film-forming plugging agent for drilling fluid according to any one of claims 1 to 5, characterized in that: The following steps are involved: First, nano silicon dioxide and polyurethane particles are mixed at a first temperature, then silicone solvent and 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 continued at a heat preservation temperature, and the reaction is cooled to room temperature to obtain a high-efficiency film-forming plugging agent for drilling fluid.

7. The preparation method according to claim 6, characterized in that: The first temperature is 60-70°C, and the second temperature is 80-90°C.

8. The preparation method according to claim 6, characterized in that: The reaction is carried out at the second temperature for 1 to 2 hours, and the reaction is continued at the second temperature for 1 to 2 hours.

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