Plant gum film-forming agent for drilling fluids and its use in drilling fluids for eastern ecuador oil fields

Abstract

This invention discloses a plant-based gum film-forming agent for drilling fluids and its application in drilling fluids in oilfields in eastern Ecuador, relating to the field of oilfield drilling technology. The plant-based gum film-forming agent for drilling fluids is prepared using the following steps: S1, take natural tara gum, add an alkaline reagent, and stir to obtain alkalized tara gum a; S2, add sodium 2-bromoethylsulfonate, heat to 70-80℃, and stir for 18-24 hours; S3, add hydrochloric acid, adjust the pH to 6.5-7.5, and add silane couplers. S4. Add sodium silicate solution to solution c and stir at 70-80℃ for 6-12 hours; S5. Cool to room temperature, wash with ethanol, precipitate solid, dry and pulverize to obtain plant gum film-forming agent powder for drilling fluid. It has excellent film-forming properties and can form a dense semi-permeable membrane on the well wall surface, effectively sealing micro-cracks, reducing the permeability and filtration loss of mud cake. It can be used in the preparation of drilling fluid for oil fields in eastern Ecuador.

Description

Technical Field

[0001] This invention relates to the field of oilfield drilling technology, specifically to plant-based film-forming agents for drilling fluids and their application in drilling fluids used in oilfields in eastern Ecuador. Background Technology

[0002] Ecuador is a country located in northwestern South America, bordering Colombia to the north, Peru to the south, and the Pacific Ocean to the west. It produces over 500,000 barrels of crude oil per day. Ecuadorian crude oil is primarily heavy, with an API value generally between 12 and 15. The main production areas are located in the eastern tropical rainforest region. Oil development in Ecuador began in the 1970s, dominated by Western multinational oil companies using relatively extensive development methods, resulting in severe environmental pollution and leading to years of international litigation. In the 21st century, Chinese oil companies began to enter Ecuador. China National Petroleum Corporation (CNPC) and China Petroleum & Chemical Corporation (Sinopec) jointly acquired Andes Petroleum Company, acquiring operating rights to Blocks 14 and 17. Engineering and technical service companies also gradually entered the market, undertaking drilling, well workover, exploration, and related professional technical services, providing equipment, materials, and technology. They have now become the leading force in Ecuadorian oil development.

[0003] The ISSPHINGO oil field in eastern Ecuador is located within the Yasuni National Park, known as the "lungs of the Earth." Boasting large reserves and high production, it is hailed as the "pearl of Ecuador's oil industry." Yasuni Park is rich in flora and fauna and is a key area for environmental protection, with extremely stringent environmental requirements. The local government explicitly requires compliance with the US Environmental Protection Agency's emission standards, even banning certain drilling fluid treatment agents, and imposing extremely high requirements on the selection and formulation of drilling and completion fluid materials. Similarly, due to environmental regulations, the government limits the number of well sites that can be built, allowing for an increase in the number of wells per site. Currently, the ISSPHINGO oil field has obtained environmental permits for two well sites, A and B, with a total of 70 wells. To maximize the utilization of formation reserves, horizontal and highly deviated wells are frequently used, increasing the difficulty of drilling operations, especially placing higher demands on drilling fluid technology.

[0004] Addressing the complex geological conditions, stringent environmental requirements, long drilling cycles, demanding wellbore trajectory requirements, and active oil-water reservoirs in the Ecuadorian rainforest region of South America, Sichuan Qingyuan Oilfield Company developed the AKUA environmentally friendly drilling fluid system, meeting the environmental and safe drilling needs of this highly sensitive area. However, the ISHPINGO oilfield, compared to other oilfield blocks, is a new block with incomplete geological understanding. Besides issues such as under-compacted new formations, poor lithology, poor wellbore stability, and severe drill bit mud buildup, it also presents unstable shale sections, particularly in deviated sections and horizontal sandstone and shale interbedded layers, leading to frequent problems like diameter reduction, collapse, and difficulty in proppant transport. Furthermore, large displacement wells, significant wellbore trajectory variations, high lubrication and drag reduction requirements, and significant challenges in protecting high-permeability reservoirs further complicate the situation. Existing technologies cannot fully meet the requirements for safe and efficient horizontal well drilling in this oilfield.

[0005] There is considerable research on plant-based gum drilling fluid systems in the existing technology. For example, the invention patent application "CN110643335A", published on January 3, 2020, discloses a modified plant-based gum for drilling fluids and its preparation method. The modified plant-based gum comprises the following components by weight: 7-11 parts guar gum, 0.6-1 parts hydrolyzed polyacrylamide, 1.1-1.3 parts borax, 0.8-1.5 parts sodium hydroxide aqueous solution, 1.2-1.5 parts ethylene oxide, and 6-6.5 parts polyurethane. The document also discloses a method for preparing this modified plant-based gum: modifying the plant-based gum under alkaline conditions further improves its viscosity, water loss reduction, and wall protection and anti-collapse capabilities, while simplifying the preparation process and reducing production costs to some extent. For example, patent application CN201510470463.9 discloses a pectinaceus plant gum-based mud and its preparation method. The pectinaceus plant gum-based mud comprises 6-12 parts by weight of pectinaceus plant gum, 0.3-0.6 parts by weight of polyacrylamide, 2-10 parts by weight of sodium hydroxide, and 800-1000 parts by weight of warm water. This invention, by adding polyacrylamide and sodium hydroxide sequentially to the dissolved pectinaceus plant gum according to this specific formula ratio, finally produces a pectinaceus plant gum-based mud with excellent rheological properties, lubrication and drag reduction properties, strong ability to carry suspended rock fragments and shear dilution ability, and good wall protection performance.

[0006] However, upon investigation, the plant-based adhesive drilling fluid system described in the aforementioned patent documents is only suitable for drilling operations in specific domestic blocks and cannot meet the drilling fluid technology requirements of the ISHPINGO oilfield in eastern Ecuador. For example, the application of hydrolyzed polyacrylamide can play a role in coating and inhibiting the MBT content of the system. However, the high mudstone content and easy hydration of the formations in eastern Ecuador mean that the application of hydrolyzed polyacrylamide will cause the drilling fluid to flocculate and stratify, resulting in poor flow and a sharp increase in water loss, thereby affecting downhole safety. In addition, considering the special geographical location and environmental protection requirements of the ISHPINGO oilfield, the selection of drilling fluid materials must prioritize environmentally friendly materials, and some commonly used materials cannot be used in this oilfield. Summary of the Invention

[0007] The proposer of this invention considered that existing technologies cannot meet the drilling operation requirements of the second and third sections of the ISSPHINGO oilfield in Ecuador. Simply relying on conventional drilling fluid technology principles such as plugging and viscosity enhancement cannot guarantee the wellbore stability and reservoir protection tasks of this oilfield. It cannot simultaneously meet the drilling fluid technology requirements of the second and third sections and horizontal formations. A single system cannot cope with different formations including mudstone, shale, sandstone and limestone. In addition, changing the wellbore structure and casing sequence is not easy to operate and implement in engineering, and it also increases well construction costs.

[0008] This invention proposes a novel plant-based gum film-forming agent for drilling fluids. This agent exhibits excellent film-forming properties, forming a dense, semi-permeable membrane on the wellbore surface, effectively sealing micro-fractures and reducing mud cake permeability and filtration loss. It also possesses good shear-dilution properties, being a pseudoplastic non-Newtonian fluid whose viscosity significantly decreases with increasing shear rate, thus contributing to the optimization of drilling fluid rheological properties. Furthermore, it is highly environmentally friendly, using natural plant gums (such as tara gum) from Ecuador and other regions as raw materials, making it non-toxic, harmless, and environmentally friendly, meeting the stringent environmental requirements of the ISHPINGO oilfield.

[0009] This invention is achieved through the following technical solution: The plant-based gum film-forming agent for drilling fluids is prepared using the following steps: S1. Take natural tarara gum, add an alkaline reagent at 40~60℃, stir for 30~60min to obtain alkalized tarara gum a; S2. Add sodium 2-bromoethylsulfonate to the alkalized tara gum a, and heat to 70-80℃ at a molar ratio of alkalized tara gum a to sodium 2-bromoethylsulfonate of 10-20:1. Stir the reaction for 18-24 hours to obtain solution b. S3. Add hydrochloric acid to solution b to adjust the pH to 6.5~7.5, add silane coupling agent, the mass ratio of silane coupling agent to alkaline Tara gel a is 1:15~20, stir and react at 70~80℃ for 6~12h to obtain solution c; S4. Add sodium silicate solution to solution c. The molar ratio of sodium silicate to alkalized Tara gum a is 1:10~15. Stir the reaction at 70~80℃ for 5~6 hours to obtain solution d. S5. Solution d is cooled to room temperature, washed with ethanol, and the solid precipitates out. It is then dried and pulverized to obtain a plant gum film-forming agent powder for drilling fluid.

[0010] Furthermore, in step S1, natural tara gum is a natural polysaccharide macromolecule extracted from the endosperm of tara plant seeds, with an average molecular weight of 150,000 to 200,000.

[0011] Furthermore, in step S1, the alkaline reagent is sodium hydroxide, potassium hydroxide, or ammonia.

[0012] Furthermore, in step S3, the silane coupling agent is one of KH550, KH560, and KH570.

[0013] Furthermore, in step S5, the drying conditions are 80~90℃ for 12 hours.

[0014] Furthermore, in step S5, a plant-based adhesive film-forming agent powder for drilling fluid is obtained, with an average particle size of 50~100μm. It dissolves in water to form a high-viscosity, quasi-plastic fluid with a film-forming strength ≥1.5MPa and a permeability coefficient ≤1×10⁻⁶. -7 cm / s.

[0015] Application of a plant-based film-forming agent for drilling fluids as described above in the preparation of drilling fluids for oil fields in eastern Ecuador.

[0016] The application of plant-based gum film-forming agents to drilling fluids can significantly improve the following properties: The wellbore stability performance, achieved through the formation of high-strength mud cake and semi-permeable membrane, effectively prevents wellbore collapse and diameter reduction; reservoir protection performance reduces the intrusion of drilling fluid filtrate into the formation, protecting reservoir permeability; lubrication and drag reduction performance lowers the friction coefficient between the drill string and the wellbore, adapting to the drilling requirements of extended reach wells and horizontal wells. In short, it meets the complex formation and high environmental protection requirements of the ISSPHINGO oilfield in Ecuador.

[0017] Furthermore, the preparation of drilling fluids for oil fields in eastern Ecuador includes the following steps: I. By weight percentage, take the following raw materials: 0.4~1.0% plant gum film-forming agent for drilling fluid, 0.2~0.5% pH adjuster, 0.6~1.2% filtration loss reducer, 0.5~1.0% thickener, 3.0~15.0% weighting agent, 0.5~1.0% vegetable oil lubricant, and the remainder is water, for later use; II. First, add water to the mixing tank, then add pH adjuster, filtration reducer, thickener, and drilling fluid plant gum film-forming agent in sequence. Stir thoroughly and mix evenly, then let stand for 24 hours to fully hydrate. Ⅲ. Next, add vegetable oil lubricant and weighting agent to the mixing tank in sequence, and stir thoroughly to obtain plant gum film-forming drilling fluid.

[0018] Furthermore, the pH adjuster is powdered magnesium oxide; the filtration loss reducer is carboxymethyl starch; and the vegetable oil lubricant is palm oil-based lubricant.

[0019] Furthermore, the thickener is high-viscosity polyanionic cellulose and xanthan gum, the viscosity range of the high-viscosity polyanionic cellulose is 1500~2000 mPa•s, the viscosity range of the xanthan gum is 1200~1600 mPa•s, and the weight ratio of the high-viscosity polyanionic cellulose to xanthan gum is 1:1.5.

[0020] Furthermore, the weighting agent comprises 200-mesh limestone powder and 325-mesh limestone powder, with a weight ratio of 1:1 between the 200-mesh limestone powder and the 325-mesh limestone powder.

[0021] Furthermore, in step I, the raw materials, by weight percentage, consist of 0.6% plant gum, 0.3% pH adjuster, 0.9% filtration loss reducer, 0.8% thickener, 10% weighting agent, 0.7% vegetable oil lubricant, and 86.7% water.

[0022] Compared with the prior art, the present invention has the following advantages and beneficial effects: I. In this invention, natural tara gum is used as the raw material. Tara gum is a natural polysaccharide polymer extracted from the endosperm of leguminous plant seeds. Its main components are D-galactose and D-mannose, preferably tara gum with a D-galactose to D-mannose ratio of 1:2. It has the advantages of being non-toxic, harmless, and environmentally friendly. The plant gum film-forming agent for drilling fluid obtained after modifying natural tara gum has excellent film-forming properties and good water solubility. It can form a stable semi-permeable membrane in drilling fluid, effectively reducing drilling fluid filtration loss, improving mud cake quality, and preventing wellbore collapse. The modified tara gum also has good lubricity, which can reduce friction between the drill string and the wellbore, and reduce the torque generated during drilling. In addition, the modified tara gum also has good temperature resistance and shear dilution resistance, making it suitable for drilling operations in complex formations, especially in drilling fluid preparation in regions such as Ecuador, meeting both environmental friendliness and technical requirements.

[0023] II. In this invention, the plant-based film-forming agent powder for drilling fluid obtained using this method is a cream-colored, loose powder, soluble in water but insoluble in organic solvents such as alcohols, ketones, and ethers. The plant-based film-forming agent solution for drilling fluid is a pseudoplastic non-Newtonian fluid; its viscosity decreases significantly with increasing shear rate, exhibiting good shear dilution properties. In drilling operations, due to well control and formation stability requirements, the bottom hole drilling fluid column pressure is usually slightly greater than the formation pressure. Under the pressure differential, the drilling fluid filtrate permeates into the formation rock and forms a mud cake on the wellbore. The filtration loss is usually greatest during the mud cake formation process, also known as the initial filtration loss or preliminary filtration loss. The main function of the plant-based film-forming agent for drilling fluid in this method is to improve the quality and permeability of the mud cake, forming a semi-permeable membrane between the drilling fluid column and the formation. The following are reference ranges for key performance indicators: Filtration loss (FLAPI): Measured by API filtration loss test, the filtration loss should be less than 10 mL (7.5 MPa differential pressure, 30 min). Plant-based film-forming agents for drilling fluids can control FLAPI levels between 5 and 8 mL, effectively reducing drilling fluid filtration loss.

[0024] Mud cake permeability coefficient: Measured by pressure osmosis test, the permeability coefficient of the mud cake should be less than 1×10⁻⁶. -7 In this scheme, the permeability coefficient of the mud cake is controlled between 0.5 and 0.8 × 10 cm / s. -7 The speed of cm / s demonstrates a good sealing effect.

[0025] The plant-based film-forming agent in this drilling fluid formulation can form a dense, semi-permeable membrane between the drilling fluid column and the formation. This not only effectively reduces early filtration loss and the permeability coefficient of the mud cake during its initial formation process, but also significantly reduces friction between the drill string and the wellbore, ensuring safe and smooth drilling operations. Furthermore, these indicators meet industry standards for high-performance water-based drilling mud, adapting to the demands of complex formations and operations with stringent environmental requirements.

[0026] Third, the plant-based adhesive film-forming agent powder for drilling fluids prepared using this method exhibits stable performance and significant advantages in film-forming properties, filtration loss control, lubricity, and environmental friendliness. It is particularly suitable for use in the preparation of drilling fluids for oil fields in eastern Ecuador.

[0027] IV. This invention also proposes a drilling fluid formulation and preparation method based on a plant-based film-forming agent for drilling fluids. The resulting drilling fluid exhibits excellent wellbore stability, low filtration loss, and high lubricity, making it suitable for drilling operations in complex formations and with stringent environmental requirements in oilfields in eastern Ecuador. This drilling fluid is particularly suitable for high-permeability formations, extended reach wells, deviated wells, and horizontal wells. The pH adjuster is used to raise the pH value of the system, maintaining it in a slightly alkaline state (pH 8-9), which is beneficial for the performance of other reagents, prevents precipitation and instability of components in the drilling fluid, and ensures the stability of the drilling fluid during long-term use. The preferred filtration reducer is carboxymethyl starch (CMS), also known as sodium carboxymethyl starch. It is odorless, non-toxic, and resistant to mold growth, making it an environmentally friendly and efficient filtration reducer. It effectively reduces the filtration loss of the drilling fluid and improves the agglomeration stability of clay particles in the drilling fluid, thereby improving mud cake quality and enhancing wellbore stability. Viscosifiers are used to maintain appropriate viscosity in the system, ensuring sufficient rheological properties in the drilling fluid to effectively carry cuttings to the surface, clean the wellbore, and prevent wellbore narrowing and blockage. The selection of viscosifiers can be adjusted according to operational needs to ensure the drilling fluid maintains good proppant carrying capacity and fluidity under various formation conditions. Weighting agents maintain the drilling fluid system density at a level of 1.05~1.15 g / cm³, maintaining bottomhole pressure and preventing overflows and blowouts. They also help maintain wellbore stability and prevent wellbore collapse, making them particularly suitable for high-pressure, high-temperature, and other special operating environments. For vegetable oil lubricants, Ecuadorian palm oil-based lubricants are preferred. These lubricants are formulated with locally produced palm oil as the base oil and domestically produced additives, offering advantages such as wide availability of raw materials, low cost, and environmental safety. This lubricant provides excellent lubrication and drag reduction in highly deviated and horizontal well drilling, reducing friction between the drill string and the wellbore, decreasing torque, improving drilling efficiency, and simultaneously reducing wellbore damage and protecting the reservoir.

[0028] V. In this invention, a water-based drilling fluid prepared using a plant-based film-forming agent for drilling fluids is employed. This fluid exhibits moderate viscosity, low filtration loss, high mud cake quality, and excellent lubrication performance. This drilling fluid is particularly suitable for drilling operations in the lower ISSPHINGO section of eastern Ecuador. Its moderate viscosity allows it to meet reservoir protection requirements while providing stable rheological properties and good wellbore cleaning.

[0029] Furthermore, this drilling fluid can meet the needs of both the upper TENA formation and the lower NAPO formation. In the TENA formation, the drilling fluid effectively prevents formation fluid intrusion into the highly permeable sandstone layers through its excellent filtration control performance and mud cake quality; in the NAPO formation, its film-forming properties and shear resistance are significant, preventing wellbore collapse and hydration instability of the shale layers.

[0030] All materials used are commonly used in the petroleum industry, such as carboxymethyl starch (CMS), high-viscosity anionic cellulose, xanthan gum, and palm oil-based lubricants. They are widely available, inexpensive, meet environmental protection requirements and engineering needs, and are particularly suitable for promotion and use in environmentally sensitive areas and complex formations.

[0031] VI. In this invention, the water-based drilling fluid exhibits significant advantages in drilling operations in both inclined and horizontal sections. It boasts high drilling speed, low torque, excellent wellbore cleaning effect, and smooth tripping and casing running processes, saving substantial non-productive time. Through field experiments and application tests, the water-based drilling fluid obtained using this method demonstrates advantages such as high drilling speed, low torque, and excellent wellbore cleaning effect, while also ensuring smooth tripping and casing running: In field tests, tripping speed was increased by 10%, resistance during casing running was significantly reduced, casing reached the designed depth in one go, and construction time was shortened by 6-8 hours, saving considerable non-productive time.

[0032] Superior lubrication performance: Through lubrication coefficient testing, the lubrication coefficient of this drilling fluid is controlled at 0.04~0.06, which significantly reduces the torque and friction loss of the drill string, and adapts to the special working conditions of highly deviated wells and horizontal wells.

[0033] Improved economic benefits: Comprehensive analysis shows that by using the water-based drilling fluid of this invention, the construction time of each well is shortened by an average of 10-15%, saving about 8-12% of the total cost of drilling operations.

[0034] VII. The drilling fluid system of this invention is simple to prepare and maintain, requiring no additional auxiliary equipment or costs, and has good application prospects in the oil fields of eastern Ecuador.

[0035] 8. In this invention, the main materials of the water-based drilling fluid are all environmentally friendly and biodegradable, harmless to human health and the natural environment, and meet the strict environmental protection requirements of the local area. Detailed Implementation

[0036] The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto.

[0037] In this invention, the plant-based gum film-forming agent for drilling fluid is obtained through the following preparation steps: S1. Take natural tarara gum, add an alkaline reagent at 40~60℃, stir for 30~60min to obtain alkalized tarara gum a; S2. Add sodium 2-bromoethylsulfonate to the alkalized tara gum a, and heat to 70-80℃ at a molar ratio of alkalized tara gum a to sodium 2-bromoethylsulfonate of 10-20:1. Stir the reaction for 18-24 hours to obtain solution b. S3. Add hydrochloric acid to solution b to adjust the pH to 6.5~7.5, add silane coupling agent, the mass ratio of silane coupling agent to alkaline Tara gel a is 1:15~20, stir and react at 70~80℃ for 6~12h to obtain solution c; S4. Add sodium silicate solution to solution c. The molar ratio of sodium silicate to alkalized Tara gum a is 1:10~15. Stir the reaction at 70~80℃ for 5~6 hours to obtain solution d. S5. Solution d is cooled to room temperature, washed with ethanol, and the solid precipitates out. It is then dried and pulverized to obtain a plant gum film-forming agent powder for drilling fluid.

[0038] To facilitate public understanding of this solution, the following embodiments use specific reagents as examples to further illustrate the solution.

[0039] Tara gum is a natural polysaccharide polymer extracted from the endosperm of leguminous plant seeds. Its main components are D-galactose and D-mannose, with an preferred average molecular weight of 150,000 to 200,000. After dissolution, it forms a high-viscosity solution exhibiting excellent shear-dilution properties. The following examples use tara gum with a 1:2 ratio of D-galactose and D-mannose and an average molecular weight of 180,000. The viscosity of the tara gum is 500–800 cP.

[0040] The alkaline reagent is one of sodium hydroxide, potassium hydroxide, or ammonia solution, depending on the modification requirements. The following examples use 5% sodium hydroxide and 5% potassium hydroxide as examples. Generally, a 5% to 10% alkaline reagent is preferable.

[0041] In step S3, the silane coupling agent is one of KH550 (γ-aminopropyltriethoxysilane), KH560 (γ-glycidoxypropyltrimethoxysilane), and KH570 (γ-methacryloyloxypropyltrimethoxysilane). In the following examples, the silane coupling agent is KH550.

[0042] When preparing drilling fluid using plant-based gum film-forming agents... The pH adjuster is powdered magnesium oxide. In the following examples, the magnesium oxide is a commercially available product, traded under the name REFIT, a white powder manufactured by INCOPET, a local company in Ecuador.

[0043] The filtration loss reducer is carboxymethyl starch (CMS), manufactured by Renqiu Pengyu Chemical Co., Ltd.

[0044] The thickener is a high-viscosity anionic cellulose and xanthan gum. The viscosity range of the high-viscosity anionic cellulose is 1500~2000 mPa•s (2% solution, 25℃, Brookfield viscometer), and the viscosity range of the xanthan gum is 1200~1600 mPa•s (1% solution, 25℃, Brookfield viscometer). In the following application example, a thickener with a weight ratio of high-viscosity anionic cellulose and xanthan gum of 1:1.5 was used for the experiment. The high-viscosity anionic cellulose was a commercially available product, PAC-HV, manufactured by Zibo Lianji Chemical Co., Ltd. High-viscosity anionic cellulose is usually prepared using its sodium salt. The xanthan gum was a commercially available product, XC-HV, with the molecular formula (C...). 35 H 49 O 29 Xanthan gum is an extracellular microbial polysaccharide produced by the fermentation of sugars by Xanthomonas aeruginosa. It has a special macromolecular structure and colloidal properties, making it an excellent thickening agent. The manufacturer is Zibo Zhongxuan Biochemical Co., Ltd.

[0045] In the following application examples, the weighting agent comprises 200-mesh limestone powder and 325-mesh limestone powder in a weight ratio of 1:1. The limestone powder is composed of calcium carbonate and is sourced locally in Ecuador.

[0046] The vegetable oil lubricant is a palm oil-based lubricant. The palm oil-based lubricant in the following application examples is a commercially available product, marketed as MUB-LUBE, a brownish-red liquid, manufactured by SOLINTOIL, a local company in Ecuador.

[0047] Example 1 In this embodiment, the product was obtained by using the preparation method of the plant gum film-forming agent for drilling fluid of the present invention, and the effects of each condition on the product performance were investigated by adjusting the parameters of each step according to the process conditions in Table 1.

[0048] The plant-based gum film-forming agent for drilling fluids is prepared using the following steps: S1. Take natural tara gum, add an alkaline reagent at 50°C, and stir for 45 minutes to obtain alkalized tara gum a. S2. Add sodium 2-bromoethylsulfonate to the alkalized tara gum a, and heat to 75°C at a molar ratio of alkalized tara gum a to sodium 2-bromoethylsulfonate of 10~20:1. Stir and react for 20 hours to obtain solution b. S3. Add hydrochloric acid to solution b to adjust the pH to 6.5~7.5. Add silane coupling agent according to the mass ratio of silane coupling agent to alkalized Tara gum a of 1:15~20. Stir and react at 80℃ for 8 hours to obtain solution c. S4. Add sodium silicate solution to solution c. The molar ratio of sodium silicate to alkaline Tara gum a is 1:10~1:15. Stir and react at 75℃ for 6 hours to obtain solution d. S5. Cool the solution d from step S4 to room temperature, wash it three times with ethanol, and precipitate a solid. Place the solid in an 80℃ drying oven and dry for 12 hours, then pulverize it to obtain a plant gum film-forming agent powder for drilling fluid.

[0049] Table 1: Parameter Settings for Each Step The plant-based adhesive film-forming agent powder products for drilling fluid obtained from groups 1 to 7 above were then tested. The test results are shown in Table 2.

[0050] It should be noted that, based on production experience and multiple experiments, the process conditions such as temperature and processing time in preparing the plant-based adhesive film-forming agent for drilling fluid should ideally be controlled within the aforementioned ranges. This embodiment takes the optimal process conditions (mainly considering cost and operational difficulty) as an example to examine the impact of the group distribution ratio on the product.

[0051] The detection methods and reference standards involved in this embodiment are as follows: Viscosity test: The viscosity value was measured using a Brookfield viscometer, 2% solution, at 25°C.

[0052] Film strength: The compressive strength of the film is measured using the standard compression test method.

[0053] Filtration loss test: The test was conducted according to the API standard method (API RP13B-1), and the filtration loss was recorded at 7.5 MPa for 30 minutes.

[0054] Cake permeability coefficient: The permeability coefficient of the cake is measured by the differential pressure permeability test method.

[0055] Lubrication coefficient: The friction coefficient between the drill string and the wellbore is measured using a lubrication performance testing device.

[0056] Table 2 illustrate: Steps S1-S5 describe the entire preparation process of the plant-based adhesive film-forming agent for drilling fluids. Under the same reaction conditions, different molar ratios of the reactants in each step were selected for each group, and their effects on the performance of the final product were tested.

[0057] The obtained drilling fluid film-forming agent powder is a cream-colored powder with an average particle size stable in the range of 50-100 μm. It dissolves in water to form a high-viscosity, quasi-plastic fluid. Table 2 shows that the film-forming strength of the obtained drilling fluid film-forming agent is greater than 1.5 MPa, with a maximum of 2.4 MPa; the permeability coefficient is ≤1×10⁻⁶. -7 It has excellent filtration rate of cm / s and excellent microcrack sealing capabilities.

[0058] Table 2 shows the performance test results of the plant-based film-forming agents for environmentally friendly drilling fluids prepared under different groups. By adjusting various process conditions, products with target performance parameters, such as viscosity, film strength, and filtration loss, can be obtained to ensure their application effect in drilling fluids.

[0059] Example 2 This embodiment examines the use of plant-based gum film-forming agent powder in the drilling fluids from each group in Example 1 to prepare drilling fluids, investigates the performance of the drilling fluids, and determines whether they are suitable for use in the development of oil fields in eastern Ecuador.

[0060] In this embodiment, the preparation of drilling fluid for oil fields in eastern Ecuador includes the following steps: I. By weight percentage, take the following raw materials: drilling fluid plant gum film-forming agent 0.4~1.0%, pH adjuster 0.2~0.5%, filtration loss reducer 0.6~1.2%, thickener 0.5~1.0%, weighting agent 3.0~15.0%, vegetable oil lubricant 0.5~1.0%, and water to make up the balance. In this example, the raw materials are taken according to the proportions of each application group in Table 3 and the test is carried out. II. First, add water to the mixing tank, then add pH adjuster, filtration reducer, thickener, and drilling fluid plant gum film-forming agent in sequence. Stir thoroughly and mix evenly, then let stand for 24 hours to fully hydrate. Ⅲ. Next, add vegetable oil lubricant and weighting agent to the mixing tank in sequence, and stir thoroughly to obtain plant gum film-forming drilling fluid.

[0061] Table 3 Comparative Example 1 The only difference between this comparative example and application group 3 is that the same mass of water was used instead of the plant-based film-forming agent in the drilling fluid, while all other conditions remained the same.

[0062] Comparative Example 2 The only difference between this comparative example and application group 4 is that the drilling fluid plant gum film-forming agent was replaced with an equal mass of unmodified Tara plant gum, while all other conditions remained the same.

[0063] Comparative Example 3 The only difference between this comparative example and application group 5 is that the drilling fluid film-forming agent was replaced with guar gum, while all other conditions remained the same.

[0064] The water-based drilling fluids prepared in application groups 1-6 and comparative examples 1-3 were then subjected to performance tests using methods commonly used in the field (GB / T 29170-2012 Standard for Laboratory Testing of Drilling Fluids in Petroleum and Natural Gas Industry). The test results are shown in Table 4.

[0065] Table 4 As shown in Tables 3 and 4, the water-based drilling fluids prepared in application groups 1 to 6 are superior to the comparative group in terms of density, viscosity, filtration loss, mud cake thickness, and lubrication performance, indicating that the plant-based gum film-forming agent has a significant effect on improving the performance of drilling fluids.

[0066] As shown in Table 4, the water-based drilling fluid prepared using plant-based film-forming agents for drilling fluids has the following characteristics: Moderate viscosity: The plastic viscosity (PV) of the drilling fluid is maintained at 10~15 mPa•s, and the dynamic shear force (YP) is controlled at 8~12 Pa, ensuring that it has good cuttings carrying capacity and rheological properties in complex wells.

[0067] Low filtration loss: The filtration loss (FLAPI) measured by API filtration loss test is controlled at 5~8 mL (7.5 MPa differential pressure, 30 minutes), which effectively reduces the risk of filtrate intruding into the formation.

[0068] High-quality mud cake: The thickness of the mud cake is controlled at 0.2~0.4 mm, and the strength reaches 1.5~2.0 MPa, which has good sealing performance and well wall stability.

[0069] Superior lubrication performance: The lubrication coefficient is less than 0.06, which significantly reduces friction between the drill string and the wellbore, and reduces torque and energy consumption during the drilling process.

[0070] This drilling fluid is particularly suitable for drilling operations in the lower section of the ISHPINGO well in eastern Ecuador. Its moderate viscosity provides stable rheological properties and good wellbore cleaning while meeting reservoir protection requirements.

[0071] Furthermore, this drilling fluid can meet the needs of both the upper TENA formation and the lower NAPO formation. In the TENA formation, the drilling fluid effectively prevents formation fluid intrusion into the highly permeable sandstone layers through its excellent filtration control performance and mud cake quality; in the NAPO formation, its film-forming properties and shear resistance are significant, preventing wellbore collapse and hydration instability of the shale layers.

[0072] In Comparative Example 1, the filtration loss (FLAPI value) increased significantly to 12.0 mL, the cake thickness increased to 0.6 mm, and the lubrication coefficient increased to 0.10, indicating a serious risk of wellbore instability.

[0073] In Comparative Examples 2 and 3, although some indicators were improved, the filtration loss, lubrication coefficient and mud cake thickness did not reach the level of the application group. It can be seen that the modified plant gum film-forming agent for drilling fluid is significantly better than the traditional material.

[0074] Furthermore, water-based drilling fluids exhibit significant advantages in drilling operations in both deviated and horizontal sections of wells. They offer faster drilling speeds, lower torque, better wellbore cleaning, and smoother tripping and casing installation processes, saving substantial non-productive time. Field experiments and application tests demonstrate that: Fast drilling speed: The mechanical drilling rate (ROP) of the inclined section of the well using the drilling fluid of this invention reaches 10~12 m / h, and the mechanical drilling rate of the horizontal section reaches 8~10 m / h, which is 15%~20% higher than that of traditional water-based drilling fluid.

[0075] Low torque: During horizontal drilling, the bottom hole torque is stable at 300~400 N•m, which is 10%~15% less than that of conventional water-based drilling fluid, effectively reducing friction between the drill string and the well wall and improving drilling efficiency.

[0076] The wellbore cleaning effect is good: Experiments show that the cuttings carrying rate is between 95% and 98%, the wellbore cleanliness is significantly improved, and the probability of complex situations such as wellbore narrowing and stuck pipe is reduced.

[0077] Smooth tripping and casing installation: In field tests, tripping speed was increased by 10%, resistance during casing installation was significantly reduced, casing reached the design depth in one go, construction time was shortened by 6-8 hours, and a lot of non-productive time was saved.

[0078] Superior lubrication performance: Through lubrication coefficient testing, the lubrication coefficient of this drilling fluid is controlled at 0.04~0.06, which significantly reduces the torque and friction loss of the drill string, and adapts to the special working conditions of highly deviated wells and horizontal wells.

[0079] Improved economic benefits: Comprehensive analysis shows that by using the water-based drilling fluid of this invention, the construction time of each well is shortened by an average of 10-15%, saving about 8-12% of the total cost of drilling operations.

[0080] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A plant-based gum film-forming agent for drilling fluids, characterized in that, The following preparation steps were used to obtain it: S1. Take natural tarara gum, add an alkaline reagent at 40~60℃, stir for 30~60min to obtain alkalized tarara gum a; S2. Add sodium 2-bromoethylsulfonate to the alkalized tara gum a, and heat to 70-80℃ at a molar ratio of alkalized tara gum a to sodium 2-bromoethylsulfonate of 10-20:

1. Stir the reaction for 18-24 hours to obtain solution b. S3. Add hydrochloric acid to solution b to adjust the pH to 6.5~7.5, add silane coupling agent, the mass ratio of silane coupling agent to alkaline Tara gel a is 1:15~20, stir and react at 70~80℃ for 6~12h to obtain solution c; S4. Add sodium silicate solution to solution c. The molar ratio of sodium silicate to alkalized Tara gum a is 1:10~15. Stir the reaction at 70~80℃ for 5~6 hours to obtain solution d. S5. Solution d is cooled to room temperature, washed with ethanol, and the solid precipitates out. It is then dried and pulverized to obtain a plant gum film-forming agent powder for drilling fluid.

2. The plant-based adhesive film-forming agent for drilling fluid according to claim 1, characterized in that: In step S1, natural tara gum is a natural polysaccharide macromolecule extracted from the endosperm of tara plant seeds, with an average molecular weight of 150,000 to 200,000.

3. The plant-based adhesive film-forming agent for drilling fluid according to claim 1, characterized in that: In step S1, the alkaline reagent is sodium hydroxide, potassium hydroxide, or ammonia.

4. The plant-based gum film-forming agent for drilling fluid according to claim 1, characterized in that: In step S3, the silane coupling agent is one of KH550, KH560, and KH570.

5. The plant-based adhesive film-forming agent for drilling fluid according to claim 1, characterized in that: In step S5, the drying conditions are 80~90℃ for 12 hours.

6. The plant-based adhesive film-forming agent for drilling fluid according to claim 1, characterized in that: In step S5, a plant-based adhesive film-forming agent powder for drilling fluid is obtained, with an average particle size of 50~100μm. It dissolves in water to form a high-viscosity, quasi-plastic fluid with a film-forming strength ≥1.5MPa and a permeability coefficient ≤1×10⁻⁶. -7 cm / s.

7. The application of the plant gum film-forming agent for drilling fluid as described in claim 1 in the preparation of drilling fluid for oil fields in eastern Ecuador.

8. The application according to claim 7, characterized in that, The preparation of drilling fluids for oil fields in eastern Ecuador includes the following steps: I. By weight percentage, take the following raw materials: 0.4~1.0% plant gum film-forming agent for drilling fluid, 0.2~0.5% pH adjuster, 0.6~1.2% filtration loss reducer, 0.5~1.0% thickener, 3.0~15.0% weighting agent, 0.5~1.0% vegetable oil lubricant, and the remainder is water, for later use; II. First, add water to the mixing tank, then add pH adjuster, filtration reducer, thickener, and drilling fluid plant gum film-forming agent in sequence. Stir thoroughly and mix evenly, then let stand for 24 hours to fully hydrate. Ⅲ. Next, add vegetable oil lubricant and weighting agent to the mixing tank in sequence, and stir thoroughly to obtain plant gum film-forming drilling fluid.

9. The application according to claim 8, characterized in that: The pH adjuster is powdered magnesium oxide; the filtration loss reducer is carboxymethyl starch; and the vegetable oil lubricant is palm oil-based lubricant.

10. The application according to claim 8, characterized in that: The thickener is a high-viscosity anionic cellulose and xanthan gum. The viscosity range of the high-viscosity anionic cellulose is 1500~2000 mPa•s, and the viscosity range of the xanthan gum is 1200~1600 mPa•s. The weight ratio of the high-viscosity anionic cellulose to xanthan gum is 1:1.

5.

11. The application according to claim 8, characterized in that: The weighting agent comprises 200-mesh limestone powder and 325-mesh limestone powder, with a weight ratio of 1:1 between the 200-mesh limestone powder and the 325-mesh limestone powder.

12. The application according to claim 8, characterized in that: In step I, the raw materials, by weight percentage, consist of 0.6% plant gum, 0.3% pH adjuster, 0.9% filtration loss reducer, 0.8% thickener, 10% weighting agent, 0.7% vegetable oil lubricant, and 86.7% water.

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