A high-efficiency, ultra-high temperature-resistant, rock-carrying water-based drilling fluid

Abstract

This invention provides a high-efficiency, ultra-high temperature-resistant, rock-carrying water-based drilling fluid. The water-based drilling fluid includes a cutting agent and a filtration loss reducer. The cutting agent is made from sepiolite and silica. This water-based drilling fluid exhibits excellent rheological properties and superior filtration loss reduction capabilities, meeting the requirements for reducing filtration loss under ultra-high temperature conditions. This satisfies the needs of drilling in ultra-high temperature formations and is of great significance for the development of hot dry rock.

Description

Technical Field

[0001] This invention belongs to the field of drilling technology, and relates to a water-based drilling fluid, and further to a high-efficiency, ultra-high temperature-resistant, rock-carrying water-based drilling fluid. Background Technology

[0002] Geothermal energy is vast and renewable. With comprehensive utilization, rational development, and sound planning, geothermal energy can be used by humankind indefinitely. Along with wind, solar, and hydropower, it is considered one of the "four major green, renewable, and clean energy resources." Developing a rational, multi-level, and cascaded utilization of geothermal resources plays a crucial role in adjusting my country's energy supply structure, ensuring energy security, alleviating energy supply pressure, and promoting regional economic development.

[0003] Compared with traditional hydrothermal geothermal resources, hot dry rock geothermal resources have advantages such as large energy reserves, wide distribution, renewability, safety, cleanliness, and no pollution, and are not limited by seasons or day / night cycles, making them an important target for geothermal energy development. However, hot dry rock drilling has three main characteristics: First, hot dry rock masses are hard, highly abrasive, and have poor drillability, resulting in low drilling efficiency, especially for large-diameter wells. Second, hot dry rock formations have high temperatures, generally between 180-650℃. Upon entering the high-temperature rock mass, the temperature inside the well rises sharply. Prolonged high temperatures will cause drastic changes in the properties of the drilling fluid, affecting cuttings carrying capacity and drill string cooling, easily leading to wellbore instability and accelerated high-temperature corrosion of the drill string. Third, hot dry rock formations have high in-situ stress. Under the alternating effects of hot and cold drilling fluid cycles, the borehole wall is prone to creep and stress release, causing wellbore spalling and inducing well accidents such as stuck drill bits. High-temperature resistant, high-efficiency rock-carrying water-based drilling fluid is key to the safe and efficient development of hot dry rock, but existing drilling fluids are insufficient to meet the needs of hot dry rock drilling.

[0004] CN 107629768 A discloses a water-based drilling fluid resistant to ultra-high temperatures. By employing a rheology stabilizer, the drilling fluid can withstand temperatures up to 260℃. This technology can effectively suppress the decomposition of drilling fluid treatment agents under ultra-high temperatures, but it does not consider the problem of thickening of the drilling fluid under ultra-high temperatures. CN 103160259 A discloses a water-based drilling fluid resistant to ultra-high temperatures of 255℃ and its construction process. This technology can effectively solve the problem of drilling fluid performance control under ultra-high temperatures, but its temperature resistance is less than 260℃, and it does not consider the performance of water-based drilling fluid under ultra-high temperatures. Therefore, the research on a high-efficiency, rock-carrying water-based drilling fluid resistant to ultra-high temperatures and its preparation method is of significant practical importance. Summary of the Invention

[0005] To address the aforementioned technical problems, this application provides a high-efficiency, ultra-high temperature-resistant, rock-carrying water-based drilling fluid. This water-based drilling fluid possesses excellent rheological properties and superior filtration loss reduction capabilities, enabling it to meet the requirements for reducing filtration loss under ultra-high temperature conditions and fulfilling the needs of drilling in ultra-high temperature formations. This is of great significance for the development of hot dry rock.

[0006] To achieve the above-mentioned technical effects, the present invention adopts the following technical solution:

[0007] This invention provides a high-efficiency, ultra-high temperature-resistant, rock-carrying water-based drilling fluid. The water-based drilling fluid includes a cutting agent and a filtration loss reducer. The raw materials of the cutting agent include sepiolite and silica.

[0008] As a preferred embodiment of the present invention, the raw material of the cutting agent further includes montmorillonite.

[0009] As a preferred embodiment of the present invention, the cutting agent comprises 1-10 parts sepiolite, 2-20 parts montmorillonite, and 1-10 parts silica by weight. The sepiolite may be in the following weight ranges: 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, or 10 parts; the montmorillonite may be in the following weight ranges: 2 parts, 3 parts, 5 parts, 8 parts, 10 parts, 12 parts, 15 parts, 18 parts, or 20 parts; and the silica may be in the following weight ranges: 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, or 10 parts. However, these are not limited to the listed values; other unlisted values ​​within the above ranges are also applicable.

[0010] As a preferred embodiment of the present invention, the preparation method of the cutting agent includes:

[0011] After the sepiolite and montmorillonite are first sieved, they are mixed with silica and ball-milled. After washing and drying, they are sieved a second time to obtain the cutting agent.

[0012] As a preferred technical solution of the present invention, the first sieving involves passing the sepiolite and montmorillonite through a sieve of 100 to 200 mesh, such as 100 mesh, 115 mesh, 120 mesh, 125 mesh, 130 mesh, 140 mesh, 150 mesh, 160 mesh, 170 mesh, 175 mesh, 180 mesh, or 200 mesh, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0013] As a preferred embodiment of the present invention, the ball mill operates at a rotational speed of 200–300 rpm for a time of 3–6 hours. The rotational speed can be 200 rpm, 210 rpm, 220 rpm, 230 rpm, 240 rpm, 250 rpm, 260 rpm, 270 rpm, 280 rpm, 290 rpm, or 300 rpm, etc., and the time can be 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours, or 6 hours, etc., but is not limited to the listed values; other unlisted values ​​within the above ranges are also applicable.

[0014] As a preferred technical solution of the present invention, the second sieving is sieve sieve of 150 to 200 mesh, such as 150 mesh, 160 mesh, 170 mesh, 175 mesh, 180 mesh or 200 mesh, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0015] As a preferred embodiment of the present invention, the filtration loss reducing agent includes sulfonated phenolic resin, sulfonated lignite resin, sulfonated pitch, and polymeric alcohol.

[0016] As a preferred embodiment of the present invention, the water-based drilling fluid further includes a pH adjuster, a reservoir protectant, an inhibitor, a lubricant, a weighting agent, and water.

[0017] As a preferred technical solution of the present invention, the water-based drilling fluid comprises, by weight, 100 parts water, 0.1-1 parts pH adjuster, 1-4 parts cutting agent, 2-6 parts sulfonated phenolic resin, 2-6 parts sulfonated lignite resin, 1-4 parts sulfonated bitumen, 1-4 parts polyol, 2-8 parts reservoir protectant, 5-10 parts inhibitor, 0.5-3 parts lubricant, and 0-100 parts weighting agent.

[0018] The pH adjuster can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1 part by weight; the shearing agent can be 1, 1.5, 2, 2.5, 3, 3.5, or 4 parts by weight; the sulfonated phenolic resin can be 2, 2.5, 3, 3.5, 4, 4.5, 5.5, or 6 parts by weight; the sulfonated lignite resin can be 2, 2.5, 3, 3.5, 4, 4.5, 5.5, or 6 parts by weight; the sulfonated bitumen can be 1, 1.5, 2, 2.5, 3, 3.5, or 4 parts by weight; and the polymeric alcohol... The mass fractions of reservoir protectants can be 1, 1.5, 2, 2.5, 3, 3.5, or 4 parts, etc.; the mass fractions of reservoir protectants can be 2, 3, 4, 5, 6, 7, or 8 parts, etc.; the mass fractions of inhibitors can be 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, or 10 parts, etc.; the mass fractions of lubricants can be 0.5, 1, 1.5, 2, 2.5, or 3 parts, etc.; and the mass fractions of weighting agents can be 1, 2, 5, 10, 15, 20, 30, 50, 80, or 100 parts, etc., but are not limited to the listed values. Other unlisted values ​​within the above ranges also apply.

[0019] Compared with the prior art, the present invention has at least the following beneficial effects:

[0020] This application provides a high-efficiency, ultra-high temperature-resistant, rock-carrying water-based drilling fluid. The water-based drilling fluid has good rheological properties and excellent filtration loss reduction capability, which can meet the requirements for reducing filtration loss under ultra-high temperature conditions and meet the needs of drilling in ultra-high temperature formations. It is of great significance for the development of hot dry rocks. Detailed Implementation

[0021] The technical solution of the present invention will be further illustrated below through specific embodiments.

[0022] This invention provides a high-efficiency, ultra-high temperature-resistant, rock-carrying water-based drilling fluid. The water-based drilling fluid includes a cutting agent and a filtration loss reducer. The raw materials for the cutting agent include sepiolite and silica.

[0023] In this invention, the cutting agent component in the water-based drilling fluid improves the hydration stability of clay at ultra-high temperatures through the introduction of sepiolite, while the introduction of silica improves the quality of the mud cake and the sealing performance of the drilling fluid.

[0024] In one specific embodiment of the present invention, the particle size of silica in the cutting agent is 50-200 nm.

[0025] In one specific embodiment of the present invention, in the preparation method of the cutting agent, 50 to 100 parts of ethanol are added to the ball milling device before ball milling.

[0026] In one specific embodiment of the present invention, in the preparation method of the cutting agent, ethanol is used to wash the ball-milled material. The drying temperature can be 50-60°C.

[0027] In one specific embodiment of the present invention, the molecular weight of the sulfonated phenolic resin can be 10,000 to 50,000, the molecular weight of the sulfonated lignite resin can be 10,000 to 50,000, the weight-average molecular weight of the sulfonated pitch can be 1,000 to 10,000, and the molecular weight of the polymeric alcohol can be 200 to 400.

[0028] In one specific embodiment of the present invention, the pH adjuster includes sodium hydroxide and / or sodium carbonate.

[0029] In one specific embodiment of the present invention, the reservoir protection agent includes any one or a combination of at least two of ultrafine calcium carbonate, unidirectional pressure shielding plugging agent, or oil film plugging agent, preferably ultrafine calcium carbonate.

[0030] In one specific embodiment of the present invention, the inhibitor includes potassium chloride and / or potassium formate.

[0031] In this invention, the introduction of inhibitors can effectively prevent formation hydration swelling and improve wellbore stability.

[0032] In one specific embodiment of the present invention, the lubricant comprises graphite and / or white mineral oil.

[0033] In this invention, the lubricant can reduce the flow loss of drilling fluid and the friction loss between the tubing and the formation.

[0034] In one specific embodiment of the present invention, the weighting agent includes any one or a combination of at least two of iron ore powder, calcium carbonate powder, barite, hematite or galena powder, preferably barite.

[0035] In one specific embodiment of the present invention, the method for preparing water-based drilling fluid includes: adding a cutting agent to water and stirring at low speed for 20-30 minutes, followed by sequentially adding a pH adjuster, sulfonated phenolic resin, sulfonated lignite resin, sulfonated pitch, polyol, reservoir protectant, inhibitor, lubricant, and weighting agent, with each treatment agent being stirred at high speed for 20 minutes after addition; the low-speed stirring is 3000-4000 r / min, and the high-speed stirring is 6000-8000 r / s.

[0036] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0037] Example 1

[0038] This embodiment provides a high-efficiency, ultra-high temperature resistant, rock-carrying water-based drilling fluid, the preparation method of which includes the following steps:

[0039] Two parts by mass of cutting agent and 0.5 parts by mass of sodium hydroxide were added to 100 parts of water. After high-speed stirring for 20 minutes, the mixture was allowed to stand at room temperature for 24 hours. The slurry was then stirred at high speed for another 20 minutes. Two parts by mass of sulfonated phenolic resin, two parts by mass of sulfonated lignite resin and one part by mass of sulfonated asphalt were added and stirred at high speed for 20 minutes. Two parts by mass of polyol, two parts by mass of ultrafine calcium carbonate, one part by mass of white mineral oil and five parts by mass of potassium chloride were added and stirred at high speed for 20 minutes. Fifty parts by mass of weighting agent were added and stirred at high speed for 20 minutes. The drilling fluid was then loaded into an aging tank and hot-rolled at 260°C for 16 hours to obtain the water-based drilling fluid F1.

[0040] The preparation method of the cutting agent includes the following steps:

[0041] Weigh 1 part sepiolite, 2 parts montmorillonite, and 1 part silica with a particle size of 50 nm and add them to a ball mill jar containing 50 parts ethanol. After ball milling at 200 rpm for 3 hours, wash the resulting composite material with anhydrous ethanol, dry it at 60°C for 2 hours, and finally sieve it through a 150-mesh sieve to obtain the cutting agent.

[0042] Example 2

[0043] This embodiment provides a high-efficiency, ultra-high temperature resistant, rock-carrying water-based drilling fluid, the preparation method of which includes the following steps:

[0044] Two parts by mass of cutting agent and 0.5 parts by mass of sodium hydroxide were added to 100 parts by mass of water. After high-speed stirring for 20 minutes, the mixture was allowed to stand at room temperature for 24 hours. The slurry was then stirred at high speed for 20 minutes. Two parts by mass of sulfonated phenolic resin, two parts by mass of sulfonated lignite resin and one part by mass of sulfonated asphalt were added and stirred at high speed for 20 minutes. Two parts by mass of polyol, two parts by mass of ultrafine calcium carbonate, one part by mass of white mineral oil and five parts by mass of potassium chloride were added and stirred at high speed for 20 minutes. Fifty parts by mass of weighting agent were added and stirred at high speed for 20 minutes. The drilling fluid was then loaded into an aging tank and hot-rolled at 260°C for 16 hours to obtain the water-based drilling fluid F2.

[0045] The preparation method of the cutting agent includes the following steps:

[0046] Five parts of sepiolite, 10 parts of montmorillonite, and 5 parts of silica with a particle size of 100 nm were weighed and added to a ball mill jar containing 100 parts of ethanol. After ball milling at 300 rpm for 3 hours, the resulting composite material was washed with anhydrous ethanol, dried at 60°C for 2 hours, and finally sieved through a 200-mesh sieve to obtain the cutting agent.

[0047] Example 3

[0048] This embodiment provides a high-efficiency, ultra-high temperature resistant, rock-carrying water-based drilling fluid, the preparation method of which includes the following steps:

[0049] Two parts by mass of cutting agent and 0.5 parts by mass of sodium carbonate were added to 100 parts by mass of water. After high-speed stirring for 20 minutes, the mixture was allowed to stand at room temperature for 24 hours. The slurry was then stirred at high speed for 20 minutes. Two parts by mass of sulfonated phenolic resin, five parts by mass of sulfonated lignite resin and four parts by mass of sulfonated asphalt were added and stirred at high speed for 20 minutes. Four parts by mass of polyol, five parts by mass of ultrafine calcium carbonate, one part by mass of modified graphite and ten parts by mass of potassium formate were added and stirred at high speed for 20 minutes. Eighty parts by mass of weighting agent were added and stirred at high speed for 20 minutes. The drilling fluid was then loaded into an aging tank and hot-rolled at 260°C for 16 hours to obtain the water-based drilling fluid F3.

[0050] The preparation method of the cutting agent includes the following steps:

[0051] Two parts sepiolite, five parts montmorillonite, and two parts silica with a particle size of 70 nm were weighed and added to a ball mill jar containing 50 parts ethanol. After ball milling at 200 rpm for 3 hours, the resulting composite material was washed with anhydrous ethanol, dried at 60°C for 2 hours, and finally sieved through a 200-mesh sieve to obtain the cutting agent.

[0052] Comparative Example 1

[0053] This comparative example provides a high-efficiency, ultra-high temperature-resistant, rock-carrying water-based drilling fluid, the preparation method of which includes the following steps:

[0054] Two parts by mass of sodium-based bentonite were added to 100 parts of water, stirred at high speed for 20 minutes, and then allowed to stand at room temperature for 24 hours. The bentonite slurry was stirred at high speed for another 20 minutes. Two parts of sulfonated phenolic resin, five parts of sulfonated lignite resin, and four parts of sulfonated asphalt were added, and stirred at high speed for 20 minutes. Four parts of polyol, five parts of ultrafine calcium carbonate, one part of modified graphite, and ten parts of potassium formate were added, and stirred at high speed for 20 minutes. Eighty parts of weighting agent were added, and stirred at high speed for 20 minutes. The drilling fluid was then loaded into an aging tank and hot-rolled at 260°C for 16 hours to obtain the water-based drilling fluid DF1.

[0055] Comparative Example 2

[0056] Except for the absence of sepiolite in the cutting agent, the conditions in this comparative example were the same as in Example 3, resulting in the water-based drilling fluid DF2.

[0057] Comparative Example 3

[0058] Except for the absence of silica in the cutting agent, the conditions in this comparative example were the same as in Example 3, resulting in the water-based drilling fluid DF3.

[0059] The sulfonated phenolic resin, with a molecular weight of about 20,000, the sulfonated lignite resin, with a molecular weight of about 20,000, the sulfonated pitch, with a molecular weight of about 8,000, and the polymeric alcohol, with a molecular weight of about 300, were used in Examples 1-3 and Comparative Examples 1-3.

[0060] The rheological and filtration properties of the water-based drilling fluids provided in Examples 1-3 and Comparative Examples 1-3 were tested, and the results are shown in Table 1.

[0061] Test method for rheological properties: Pour the drilling fluid to be tested into the sample cup and place it on the sample cup holder of the instrument. Adjust the height so that the liquid level of the drilling fluid is exactly at the measuring line of the rotating drum. Set the speed of the six-speed selective viscometer to 600 r / min. After the reading stabilizes, read and record the value. Read and record the readings at 300, 200, 100, 6, and 3 r / min in the same way. Stir at 600 r / min for 10 seconds, let stand for 10 seconds, and then read and record the maximum reading at 3 r / min. Stir again at 600 r / min for 10 seconds, let stand for 10 minutes, and then read and record the maximum reading at 3 r / min.

[0062]

[0063] PV = Φ 600 -Φ 300

[0064] YP = 0.511(Φ 300 -PV)

[0065] in:

[0066] Φ 600 —The reading at 600 r / min on the viscometer;

[0067] Φ 300 —The reading of 300 r / min on the viscometer;

[0068] AV—apparent viscosity, mPa·s;

[0069] PV—plastic viscosity, mPa·s;

[0070] YP—Dynamic shear force, Pa.

[0071] Test methods for filtration performance:

[0072] ①API medium pressure filtration (FL) API )

[0073] Filtration loss was measured using a medium-pressure filtration loss meter manufactured by Qingdao Tongchun Instrument Co., Ltd. The filter screen cover, filter paper, and rubber ring were installed on the base in sequence according to the operating procedure. Drilling fluid was poured into the tank to the graduation mark, the fixing nut was tightened, the venting device was connected, the measuring cylinder was placed at the liquid outlet at the bottom of the container, the pressure was adjusted to 0.69 MPa, and the venting valve was opened simultaneously with the start of timing. The drilling fluid filtration loss over 30 minutes was taken as the measurement result.

[0074] ② High temperature and high pressure filtration loss (FL) HTHP )

[0075] Filtration loss was determined using a high-temperature, high-pressure filtration loss meter manufactured by Qingdao Tongchun Instrument Co., Ltd. The vent valve stem on the top of the pressure tank was installed, and the vent valve was closed by rotating it. The drilling fluid to be tested was poured into the tank from the bottom to the mark. The sealing ring, filter paper, and filter screen were installed in sequence. The cover was then tightened, and the internal hex screws were turned off, and the vent valve was closed. The tank was placed face up into the heating device, and the preset temperature was adjusted. The metal thermometer was inserted into the pre-drilled measuring hole, and the sealing of all valve stems was checked. The upper and lower pressurization vent hoses were connected. According to the standard, the upper pressure was adjusted to the specified value corresponding to the temperature. The vent valve on the sealed tank was opened, and venting was performed for 10 seconds, then the upper vent valve was closed. After the temperature reached the set temperature, the upper and lower pressures were adjusted to the specified values ​​under the set test temperature conditions. The upper and lower vent valves were opened (note that the upper vent valve should be opened first, then the lower vent valve), and the timing was started. Intermittently and slowly open the filtrate outlet valve at the bottom of the tank, collect the filtrate with a graduated cylinder, and record the total filtrate loss within 30 minutes. Multiply the obtained filtrate loss by 2 to obtain the final filtrate loss.

[0076] Table 1

[0077] Drilling fluid AV,mPa.s PV, mPa.s YP,Pa 10s / 10min <![CDATA[FL API ,mL]]> <![CDATA[FL HTHP ,mL]]> F1 62 45 17 5 / 9 3.4 19.6 F2 68 49 19 6 / 9.5 2.8 16.8 F3 77 57 20 8 / 11 2.4 13.2 DF1 40 32 8 2 / 5 5.6 36.0 DF2 32 26 6 2 / 4 6.2 39.8 DF3 52 39 13 4 / 8 8.3 50.2

[0078] As can be seen from the rheological and filtration performance test results in Table 1, the drilling fluid of the present invention has good rheological properties and excellent filtration reduction capability. It can meet the requirements for reducing filtration under ultra-high temperature conditions, meet the needs of drilling in ultra-high temperature formations, and is of great significance for the development of hot dry rocks.

[0079] The applicant declares that the detailed process equipment and process flow of this invention are illustrated through the above embodiments, but this invention is not limited to the above detailed process equipment and process flow, that is, it does not mean that this invention must rely on the above detailed process equipment and process flow to be implemented. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials for the products of this invention, additions of auxiliary components, and selection of specific methods, all fall within the protection scope and disclosure scope of this invention.

Claims

1. A high-efficiency, ultra-high temperature-resistant, rock-carrying water-based drilling fluid, characterized in that, The water-based drilling fluid includes a cutting agent and a filtration loss reducer, wherein the raw materials for the cutting agent include sepiolite and silica; The raw materials for the cutting agent also include montmorillonite; The cutting agent, by weight, comprises 1-10 parts sepiolite, 2-20 parts montmorillonite, and 1-10 parts silica. The filtration loss reducing agent includes sulfonated phenolic resin, sulfonated lignite resin, sulfonated pitch, and polymeric alcohol.

2. The water-based drilling fluid according to claim 1, characterized in that, The preparation method of the cutting agent includes: After the sepiolite and montmorillonite are first sieved, they are mixed with silica and ball-milled. After washing and drying, they are sieved a second time to obtain the cutting agent.

3. The water-based drilling fluid according to claim 2, characterized in that, The first sieving involves passing the sepiolite and montmorillonite through a 100-200 mesh sieve.

4. The water-based drilling fluid according to claim 2, characterized in that, The ball milling speed is 200~300 rpm, and the time is 3~6 h.

5. The water-based drilling fluid according to claim 2, characterized in that, The second sieving process involves passing the material through a 150-200 mesh sieve.

6. The water-based drilling fluid according to claim 1, characterized in that, The water-based drilling fluid also includes pH adjusters, reservoir protectants, inhibitors, lubricants, weighting agents, and water.

7. The water-based drilling fluid according to claim 6, characterized in that, The water-based drilling fluid, by weight, comprises 100 parts water, 0.1-1 parts pH adjuster, 1-4 parts cutting agent, 2-6 parts sulfonated phenolic resin, 2-6 parts sulfonated lignite resin, 1-4 parts sulfonated bitumen, 1-4 parts polyol, 2-8 parts reservoir protectant, 5-10 parts inhibitor, 0.5-3 parts lubricant, and 0-100 parts weighting agent.

Images