Highly dispersible fibrous lost circulation material for water-based drilling fluids, and applications and methods thereof

Abstract

The application discloses a high-dispersion fiber leak-stopping agent for water-based drilling fluid and application and application method thereof, and relates to the technical field of drilling fluid leak-stopping used in oil and gas exploitation. The high-dispersion fiber leak-stopping agent for water-based drilling fluid contains 10.0-20.0% of high-dispersion high-aspect-ratio synthetic fiber, 10.0-40.0% of high-temperature-resistant natural fiber, 10.0-20.0% of wood fiber, 10.0-30.0% of spina date kernel particles and 5.0-10.0% of microporous foam aluminum particles in percentage of mass. The high-dispersion fiber leak-stopping agent for water-based drilling fluid can be directly added into the water-based drilling fluid, can pass through the internal gap of the rotary steering tool and will not block the rotary steering tool, and the rotary steering drilling tool does not need to be first tripped out. The application solves the problem of leak-stopping while drilling under the condition of the rotary steering drilling tool. The application provides technical support for the exploration and development of unconventional oil and gas resources such as shale gas, coalbed gas and tight gas.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of oil and gas exploitation, in particular to the field of drilling fluid plugging used in the process of oil and gas exploitation, and more particularly to a high-dispersible fiber plugging agent for water-based drilling fluid, and an application method and method thereof. BACKGROUND

[0002] With the rapid development of the national economy, the demand for natural gas continues to increase. Under the new goal of "double carbon", China's demand for natural gas is more obvious, and it is expected to reach 420-500 billion cubic meters in 2025. Under the driving of strong demand, shale gas, coalbed methane, and other unconventional oil and gas resources have ushered in a good development opportunity. At present, shale gas, coalbed methane, and other unconventional oil and gas resources are explored and exploited by using horizontal wells. Directional drilling is required during the drilling process of horizontal wells. The rotary steerable drilling tool solves the defects of sliding directional technology and is widely used in the construction of large displacement wells, long horizontal wells, high-difficulty directional wells, and multi-branch horizontal wells.

[0003] The rotary steerable drilling tool has a small internal gap, usually not more than 3mm, and the conventional plugging agent cannot pass through the internal gap of the rotary steerable drilling tool, which easily causes internal plugging of the rotary steerable drilling tool. Therefore, when well leakage occurs, plugging cannot be performed at the first time, and the rotary steerable drilling tool must be pulled out first, then the ordinary drilling tool is lowered to plug. Frequent tripping not only causes low drilling efficiency, but also may cause rapid decrease of the liquid column pressure in the wellbore, resulting in rapid decrease of the liquid column pressure of the horizontal section rock layer, large-scale collapse of the well bottom, and serious well control risk.

[0004] Therefore, the problem of plugging while drilling using the rotary steerable drilling tool is a bottleneck problem restricting the application of the rotary steerable drilling tool, and is also a key technical problem restricting the exploration and development of shale gas, coalbed methane, and other unconventional oil and gas resources.

[0005] In summary, when the rotary steerable drilling tool is used, the following problems exist in the construction process when well leakage occurs, which need to be overcome:

[0006] 1. The rotary steerable drilling tool has a small internal gap, usually not more than 3mm, and the size specification of the plugging agent is strictly required, so most of the conventional plugging agents used at present cannot be applied to the plugging of the horizontal section using the rotary steerable drilling tool.

[0007] 2. When the rotary steerable drilling tool is used, only fine-grained plugging agents for drilling while plugging can be used, but the conventional plugging agents for drilling while plugging are mostly powdery, and the plugging effect for fractured well leakage is poor, which cannot meet the plugging needs.

[0008] 3. In the past, when using rotary steerable drilling tools and encountering severe well leakage, it was impossible to plug the leakage immediately (conventional lost circulation plugging agents were ineffective). The drill string had to be pulled out first, the rotary steerable drilling tool discarded, and then a conventional drill string had to be run in for plugging. This process was complex and inefficient.

[0009] 4. If plugging operations cannot be carried out immediately in case of severe well leakage, it will cause a significant reduction in the pressure of the drilling fluid column at the bottom of the well, leading to the collapse of the bottom rock and potentially causing oil and gas to enter the well, resulting in serious well control risks.

[0010] Therefore, there is an urgent need to develop a water-based drilling fluid plugging agent that can be used for plugging leaks while drilling with rotary steerable drilling tools. This plugging agent must have good dispersibility, not clump together, and be able to pass through the internal gaps of rotary steerable drilling tools, providing good plugging performance for fractured well losses, and meeting the requirements of horizontal wells such as shale gas, coalbed methane, and tight gas for plugging agents while drilling. Summary of the Invention

[0011] To overcome the shortcomings of the existing technology, this invention provides a highly dispersed fiber plugging agent for water-based drilling fluids, its application, and a method thereof. The purpose of this invention is to solve the problem of conventional plugging agents being insufficient for plugging leaks in horizontal sections of shale gas, coalbed methane, and tight gas wells using rotary steerable drilling tools (STOs). The highly dispersed fiber plugging agent for water-based drilling fluids provided by this invention is prepared by mixing highly dispersed, high aspect ratio synthetic fibers, high-temperature resistant natural fibers, wood fibers, jujube kernel particles, and microporous aluminum foam particles. This highly dispersed fiber plugging agent can be directly added to water-based drilling fluids, can pass through the internal gaps of STOs without clogging them, and eliminates the need for tripping out the drill string and discarding the STO. It solves the problem of plugging leaks while drilling under conditions with STOs. This provides technical support for the exploration and development of unconventional oil and gas resources such as shale gas, coalbed methane, and tight gas.

[0012] To address the problems existing in the prior art, the present invention is achieved through the following technical solution.

[0013] The first aspect of this invention provides a highly dispersed fiber plugging agent for water-based drilling fluids, the plugging agent comprising...

[0014] Highly dispersed, high aspect ratio synthetic fibers of 10.0%-20.0%;

[0015] 10.0%-40.0% high-temperature resistant natural fibers;

[0016] 10.0%-20.0% wood fiber;

[0017] 10.0%-30.0% of the Chinese date kernel particles;

[0018] 5.0%-10.0% of the microporous aluminum foam particles.

[0019] Further preferably, the high-dispersion high-aspect-ratio synthetic fiber is any one or a combination of polyester fiber, polyvinyl alcohol fiber, and polyacrylonitrile fiber.

[0020] More preferably, the high-dispersion high-aspect-ratio synthetic fiber has an aspect ratio of 300-1000.

[0021] Further preferably, the high-temperature-resistant natural fiber is any one or a combination of sepiolite fiber and basalt fiber.

[0022] More preferably, the high-temperature-resistant natural fiber has an average length of 1.0 mm-3.0 mm.

[0023] Further preferably, the Chinese date kernel particles have an average particle size of 10-40 mesh.

[0024] Further preferably, the microporous aluminum foam has an average particle size of 10-40 mesh and a density of 1.0 g / cm 3 -1.3 g / cm 3 .

[0025] The second aspect of the present application provides a high-dispersion fiber plugging agent for water-based drilling fluid for use in drilling operations with a rotary steerable drilling tool.

[0026] The third aspect of the present application provides a method for using a high-dispersion fiber plugging agent for water-based drilling fluid in drilling operations with a rotary steerable drilling tool. In the drilling operation with a rotary steerable drilling tool, when a loss occurs, the drilling does not need to be raised, and the high-dispersion fiber plugging agent for water-based drilling fluid is directly added to the water-based drilling fluid for drilling plugging.

[0027] Further, under stirring conditions, the high-dispersion fiber plugging agent for water-based drilling fluid is added to the water-based drilling fluid, which can pass through the internal gap of the rotary steerable tool and will not block the rotary steerable drilling tool.

[0028] Compared with the prior art, the present application has the beneficial technical effects of:

[0029] 1. The high-dispersion fiber leak-stopper for water-based drilling fluid provided by the present application has the advantages of fast dispersion, no aggregation, good leak-stopping effect, high pressure-bearing capacity, high temperature resistance, no easy re-leakage after leak-stopping, simple operation, no need to trip and change the drilling tool, and the ability to be added into the drilling fluid for leak-stopping while drilling at the first time of discovering the leakage, thus solving the problem of low efficiency and easy downhole collapse caused by the necessity of tripping and changing the drilling tool before leak-stopping under the condition of using the rotary steering drilling tool, improving the efficiency of leak-stopping operation, and meeting the needs of safe and fast drilling of horizontal wells in shale gas, coalbed methane and tight gas.

[0030] 2. The high-dispersion fiber leak-stopper for water-based drilling fluid provided by the present application has good dispersibility in the water-based drilling fluid, can be dispersed by simple stirring, and thus can smoothly pass through the internal gap of the rotary steering drilling tool without blocking the rotary steering drilling tool.

[0031] 3. The high-dispersion fiber leak-stopper for water-based drilling fluid provided by the present application is simple to apply and does not need to trip and change the drilling tool. When the leakage is encountered, the rotary steering drilling tool does not need to be tripped, and the high-dispersion fiber leak-stopper can be directly added into the water-based drilling fluid for simple stirring and then injected into the well for leak-stopping, thus overcoming the defect that the rotary steering drilling tool needs to be tripped and changed before leak-stopping when the leakage is encountered.

[0032] 4. The high-dispersion fiber leak-stopper for water-based drilling fluid provided by the present application can immediately leak-stop at the first time of discovering the leakage, thus solving the problem of downhole rock collapse caused by the rapid drop of the drilling fluid level in the wellbore and the reduction of the liquid column pressure at the bottom of the well due to long-time tripping.

[0033] 5. The leak-stopper for water-based drilling fluid provided by the present application contains high-dispersion fibers to play a role of reinforcing bars and has good leak-stopping effect on crack leakage. When the rotary steering drilling tool is used, only leak-stopping agents with fine particles can be used, but the conventional leak-stopping agents are powdery and have poor leak-stopping effect on crack leakage, thus failing to meet the leak-stopping needs.

[0034] 6. The high-dispersion fiber leak-stopper for water-based drilling fluid provided by the present application has a high-temperature resistance of up to 200 DEG C, and the synthetic fibers, high-temperature resistant natural fibers and aluminum foam particles all have good temperature resistance. In the past, the bottom hole temperature was high, 130 DEG C to 160 DEG C, during the construction of deep shale gas horizontal wells. Most leak-stoppers decomposed at high temperatures, which easily caused re-leakage. Frequent leak-stopping consumed a large amount of leak-stopping materials.

[0035] 7. The leak-stopper for water-based drilling fluid provided by the present application contains aluminum foam particles and spina date particles, has strong pressure-bearing capacity, and has a pressure-bearing capacity of 12 MPa for 1-5 mm cracks. The leak-stopping strength is high, and re-leakage is not easy. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 Figure 1 is a schematic diagram of the comparison of the transparent tube sand bed invasion depth of the test slurry 10 and the test slurries 11, 12, 13 and 14 in the test example 1 of the present application;

[0037] Figure 2 Figure 2 is a schematic diagram of the comparison of the water loss of the test slurry 10 and the test slurries 11, 12, 13 and 14 in the test example 1 of the present application;

[0038] Figure 3 Figure 3 is a schematic diagram of the comparison of the plugging filtration loss of the test slurry 10 and the test slurries 11, 12, 13 and 14 in the test example 1 of the present application;

[0039] Figure 4 Figure 4 is a schematic diagram of the comparison of the filtration loss of the test slurry 20 and the test slurry 21 under different fracture plate widths in the test example 2 of the present application;

[0040] Figure 5 Figure 5 is a schematic diagram of the comparison of the filtration loss of the test slurry 20 and the test slurry 22 under different filtration pressures in the test example 2 of the present application;

[0041] Figure 6 Figure 6 is a schematic diagram of the comparison of the filtration loss of the test slurry 20 and the test slurry 23 after hot rolling at different temperatures in the test example 2 of the present application. DETAILED DESCRIPTION

[0042] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the specification of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0043] It should be noted that the terms "comprise", "comprising", "include", "including" and any variations thereof in the specification and claims of the present application and the above-mentioned drawings are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device comprising a series of steps or units does not have to be limited to only those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0044] The "range" disclosed in the present application is given in the form of lower limit and upper limit. There can be one or more lower limits, and one or more upper limits. The given range is limited by selecting a lower limit and an upper limit. The selected lower limit and upper limit define the boundary of a particular range. All ranges defined in this way are combinable, i.e. any lower limit can be combined with any upper limit to form a range.

[0045] In the present application, all the embodiments and preferred embodiments mentioned in the present application can be combined with each other to form new technical solutions if no special instructions are given.

[0046] In the present application, all the technical features and preferred features mentioned in the present application can be combined with each other to form new technical solutions if no special instructions are given.

[0047] In order to make the purpose, technical solutions and advantages of the present application more clear, the present application is further described in detail below in combination with the accompanying tables, drawings and examples. The examples described below are part of the examples of the present application, not all the examples, and are only used to illustrate the present application, and should not be regarded as limiting the scope of the present application. Based on the examples in the present application, all the other examples obtained by those skilled in the art without making creative efforts fall within the scope of protection of the present application. If no specific conditions are mentioned in the examples, the conventional conditions or the conditions recommended by the manufacturers are used. If the reagents or instruments used are not mentioned by the manufacturers, they are all conventional products that can be purchased in the market.

[0048] Since 2019, experimental drilling of deep shale gas horizontal wells has been carried out in Ordos Basin. Serious well leakage occurs during drilling of the horizontal section. Due to the limitation of rotary steering drilling tools, most conventional plugging agents cannot be used directly, and the drilling tools must be replaced before plugging. During the tripping process, the wellbore fluid level drops rapidly due to well leakage, the liquid column pressure at the bottom of the well is reduced, and shale collapse is caused. Forced well filling and sidetracking are carried out, and the geological exploration target is not completed.

[0049] Therefore, we have developed a high-dispersion fiber plugging agent technology for horizontal wells, which has been successfully applied in ZP-2, QT-10 and other wells, solving the problem of drilling plugging under the condition of rotary steering drilling tools. It provides technical support for the exploration and development of unconventional oil and gas resources such as shale gas, coalbed methane and tight gas.

[0050] Example 1

[0051] As a preferred embodiment of the present application, the present embodiment provides a high-dispersion fiber plugging agent for water-based drilling fluid, which comprises

[0052] 10.0% of high-dispersion high-aspect-ratio synthetic fiber;

[0053] 40.0% of high-temperature-resistant natural fiber;

[0054] 20.0% of wood fiber;

[0055] 25.0% of Chinese wingnut kernel particles;

[0056] 5.0% of microporous aluminum foam particles;

[0057] In the present embodiment, the high-dispersion high-aspect-ratio synthetic fiber is polyester fiber; the high-aspect-ratio synthetic fiber has an aspect ratio of 600; the high-temperature-resistant natural fiber is sepiolite fiber; the average length of the high-temperature-resistant natural fiber is 2.0-3.0 mm; the average particle size of the spina-christi particles is 10-20 mesh; the average particle size of the microporous aluminum foam is 10-20 mesh; the density is 1.1 g / cm 3 .

[0058] Comparative Example 1

[0059] The present comparative example provides a blank water-based drilling fluid without high-dispersion fiber plugging agent, wherein the blank water-based drilling fluid comprises, based on the total weight of the clean water used in preparing the blank water-based drilling fluid, by weight:

[0060] bentonite: 3.0%, sodium hydroxide: 0.3%, limestone powder 325 mesh: 5.0%, and clean water.

[0061] The blank water-based drilling fluid provided in the present comparative example is prepared by a preparation method comprising the following specific steps:

[0062] Under the condition of high-speed stirring, the bentonite, sodium hydroxide, limestone powder 325 mesh are sequentially added to the clean water according to the proportion, and the blank water-based drilling fluid is prepared after stirring uniformly, which is recorded as test slurry 10.

[0063] Comparative Example 2

[0064] The present comparative example provides a water-based drilling fluid with high-dispersion fiber plugging agent, wherein the water-based drilling fluid comprises, based on the total weight of the clean water used in preparing the water-based drilling fluid, by weight:

[0065] bentonite: 3.0%, sodium hydroxide: 0.3%, limestone powder 325 mesh: 5.0%, fiber plugging agent: 5%, and clean water.

[0066] The water-based drilling fluid provided in the present comparative example is prepared by a preparation method comprising the following specific steps:

[0067] Under the condition of high-speed stirring, the bentonite, sodium hydroxide, limestone powder 325 mesh, fiber plugging agent are sequentially added to the clean water according to the proportion, and the water-based drilling fluid is prepared after stirring uniformly, which is recorded as test slurry 11.

[0068] Comparative Example 3

[0069] The present comparative example provides a water-based drilling fluid with single seal (commonly used while drilling plugging agent), wherein the water-based drilling fluid comprises, based on the total weight of the clean water used in preparing the water-based drilling fluid, by weight:

[0070] Bentonite: 3.0%, Sodium hydroxide: 0.3%, Limestone powder 325 mesh: 5.0%, Single seal: 5% and water.

[0071] The water-based drilling fluid provided in this comparative example was prepared by a preparation method comprising the following specific steps:

[0072] Under the condition of high-speed stirring, the bentonite, sodium hydroxide, limestone powder 325 mesh, and single seal were sequentially added into water according to the proportion, and the water-based drilling fluid was prepared after uniform stirring, which was recorded as test slurry 12.

[0073] Comparative Example 4

[0074] This comparative example provides a water-based drilling fluid added with walnut shell particles (a commonly used plugging agent), wherein the water-based drilling fluid comprises, based on the total weight of water used for preparing the water-based drilling fluid as 100%:

[0075] Bentonite: 3.0%, Sodium hydroxide: 0.3%, Limestone powder 325 mesh: 5.0%, Walnut shell particles: 5% and water.

[0076] The water-based drilling fluid provided in this comparative example was prepared by a preparation method comprising the following specific steps:

[0077] Under the condition of high-speed stirring, the bentonite, sodium hydroxide, limestone powder 325 mesh, and single seal were sequentially added into water according to the proportion, and the water-based drilling fluid was prepared after uniform stirring, which was recorded as test slurry 12.

[0078] Comparative Example 5

[0079] This comparative example provides a water-based drilling fluid added with mica flakes (a commonly used plugging agent), wherein the water-based drilling fluid comprises, based on the total weight of water used for preparing the water-based drilling fluid as 100%:

[0080] Bentonite: 3.0%, Sodium hydroxide: 0.3%, Limestone powder 325 mesh: 5.0%, Mica flakes: 5% and water.

[0081] The water-based drilling fluid provided in this comparative example was prepared by a preparation method comprising the following specific steps:

[0082] Under the condition of high-speed stirring, the bentonite, sodium hydroxide, limestone powder 325 mesh, and single seal were sequentially added into water according to the proportion, and the water-based drilling fluid was prepared after uniform stirring, which was recorded as test slurry 12.

[0083] Example 2

[0084] As a preferred embodiment of the present application, this example provides a high-dispersion fiber plugging agent for water-based drilling fluid, which comprises

[0085] 15.0% of high-dispersion high-aspect-ratio synthetic fiber;

[0086] 35.0% of high-temperature-resistant natural fiber;

[0087] 20.0% of wood fiber;

[0088] 20.0% of Chinese wingnut kernel particles;

[0089] 10.0% of microporous aluminum foam particles;

[0090] In this embodiment, the high-dispersion high-aspect-ratio synthetic fiber is polyester fiber; the aspect ratio of the high-dispersion high-aspect-ratio synthetic fiber is 800; the high-temperature-resistant natural fiber is sepiolite fiber; the average length of the high-temperature-resistant natural fiber is 2.0-3.0 mm; the average particle size of the Chinese wingnut kernel particles is 20-30 mesh; the average particle size of the microporous aluminum foam is 20-30 mesh; and the density is 1.2 g / cm3.

[0091] The plugging agent is added to a water-based drilling fluid, wherein the water-based drilling fluid comprises, based on the total weight of the clean water used to prepare the water-based drilling fluid, 3.0% bentonite, 0.3% sodium hydroxide, 5.0% limestone powder 325 mesh, 5% of the plugging agent, and clean water.

[0092] The water-based drilling fluid provided in this comparative example is prepared by a preparation method comprising the following specific steps:

[0093] Under the condition of high-speed stirring, the bentonite, the sodium hydroxide, the limestone powder 325 mesh, and the plugging agent are sequentially added to the clean water in a proportioning manner, and the water-based drilling fluid is prepared after uniform stirring, which is recorded as test slurry 20.

[0094] Comparative Example 6

[0095] This embodiment provides a plugging agent without using polyester fiber, and the plugging agent without using polyester fiber is added to a water-based drilling fluid, wherein the water-based drilling fluid comprises, based on the total weight of the clean water used to prepare the water-based drilling fluid, 3.0% bentonite, 0.3% sodium hydroxide, 5.0% limestone powder 325 mesh, and 5% of the plugging agent without using polyester fiber.

[0096] The water-based drilling fluid provided in this comparative example is prepared by a preparation method comprising the following specific steps:

[0097] The plugging agent comprises, in mass percentage, 40.0% sepiolite fiber, 20.0% wood fiber, 30.0% Chinese wingnut kernel particles, and 10.0% microporous aluminum foam particles.

[0098] The plugging agent comprises, in mass percentage, 40.0% sepiolite fiber, 20.0% wood fiber, 30.0% Chinese wingnut kernel particles, and 10.0% microporous aluminum foam particles.

[0099] The water-based drilling fluid provided in the present comparative example is prepared by a preparation method comprising the following specific steps:

[0100] Under the condition of high-speed stirring, the bentonite, sodium hydroxide, limestone powder 325 mesh, and plugging agent are sequentially added into the clean water in the proportion, and the water-based drilling fluid is prepared after uniform stirring, which is recorded as test slurry 21.

[0101] Comparative Example 7

[0102] The present embodiment provides a plugging agent without using microporous aluminum foam particles, and the plugging agent without using microporous aluminum foam particles is added into a water-based drilling fluid, wherein the water-based drilling fluid comprises, based on the total weight of the clean water used when the water-based drilling fluid is prepared as 100%:

[0103] Bentonite: 3.0%, sodium hydroxide: 0.3%, limestone powder 325 mesh: 5.0%, plugging agent: 5%, and clean water.

[0104] The plugging agent comprises, based on the mass percentage:

[0105] 20.0% polyester fiber, 40.0% sepiolite fiber, 20.0% wood fiber, and 20.0% zizyphus jujuba mill particle.

[0106] The water-based drilling fluid provided in the present comparative example is prepared by a preparation method comprising the following specific steps:

[0107] Under the condition of high-speed stirring, the bentonite, sodium hydroxide, limestone powder 325 mesh, and plugging agent are sequentially added into the clean water in the proportion, and the water-based drilling fluid is prepared after uniform stirring, which is recorded as test slurry 22.

[0108] Comparative Example 8

[0109] The present embodiment provides a plugging agent using only wood fiber and zizyphus jujuba mill particle, and the plugging agent is added into a water-based drilling fluid, wherein the water-based drilling fluid comprises, based on the total weight of the clean water used when the water-based drilling fluid is prepared as 100%:

[0110] Bentonite: 3.0%, sodium hydroxide: 0.3%, limestone powder 325 mesh: 5.0%, plugging agent: 5%, and clean water.

[0111] The plugging agent comprises, based on the mass percentage: 50.0% wood fiber and 50.0% zizyphus jujuba mill particle.

[0112] The water-based drilling fluid provided in the present comparative example is prepared by a preparation method comprising the following specific steps:

[0113] The water-based drilling fluid was prepared by adding bentonite, sodium hydroxide, limestone powder 325 mesh, and plugging agent into water in the proportion under high-speed stirring, and was recorded as test slurry 23.

[0114] Example 3

[0115] The plugging agent of the present example is prepared by using polyester fiber with aspect ratio of 300-1000 and fiber diameter of 6 µm, sepiolite fiber, wood fiber, zizyphus jujuba mill particle, and microporous aluminum foam particle.

[0116] The plugging agent comprises, in mass percentage:

[0117] 20.0% polyester fiber, 40.0% sepiolite fiber, 25.0% wood fiber, 10.0% zizyphus jujuba mill particle, and 5.0% microporous aluminum foam particle.

[0118] Comparative Example 9

[0119] The plugging agent of the present example is prepared by using polyester fiber with aspect ratio of 3000 and fiber diameter of 6 µm, sepiolite fiber, wood fiber, zizyphus jujuba mill particle, and microporous aluminum foam particle.

[0120] The plugging agent comprises, in mass percentage:

[0121] 20.0% polyester fiber, 40.0% sepiolite fiber, 25.0% wood fiber, 10.0% zizyphus jujuba mill particle, and 5.0% microporous aluminum foam particle.

[0122] The plugging agent of the present example is prepared by using polyester fiber with aspect ratio of 3000 and fiber diameter of 6 µm, sepiolite fiber, wood fiber, zizyphus jujuba mill particle, and microporous aluminum foam particle.

[0123] Comparative Example 10

[0124] The plugging agent of the present example is prepared by using polyester fiber with aspect ratio of 5000 and fiber diameter of 6 µm, sepiolite fiber, wood fiber, zizyphus jujuba mill particle, and microporous aluminum foam particle.

[0125] The plugging agent comprises, in mass percentage:

[0126] 20.0% polyester fiber, 40.0% sepiolite fiber, 25.0% wood fiber, 10.0% zizyphus jujuba mill particle, and 5.0% microporous aluminum foam particle.

[0127] The plugging agent of the present example is prepared by using polyester fiber with aspect ratio of 5000 and fiber diameter of 6 µm, sepiolite fiber, wood fiber, zizyphus jujuba mill particle, and microporous aluminum foam particle.

[0128] Test Example 1

[0129] This test example uses a portable non-permeable drilling fluid filtration meter to test the penetration depth of test fluids 10, 11, 12, 13, and 14 in a 0.7 MPa transparent tubular sand bed (a commonly used evaluation method in this field). This is used to analyze and compare the plugging performance of water-based drilling fluids with different plugging agents.

[0130] Pour 180 mL of 60-80 mesh fine sand into a portable non-permeable drilling fluid filtration meter. Shake the sand surface to level it, then slowly inject 180 mL of test slurry. Connect and fix the glass tube and the air source. Turn on the air source, pressurize to 0.7 MPa, hold the pressure for 5 minutes, and then slowly open the outlet valve. Perform the experiment for 30 minutes, and measure and record the depth of the test slurry immersing in the sand bed.

[0131] The comparison of the penetration depth of test slurries 10 to 14 is as follows: Figure 1 As shown. From Figure 1 As can be seen, the penetration depth of test slurry 11 obtained by adding fiber plugging agent in Example 1 is the smallest, and the penetration depth of test slurry 11 is significantly lower than that of test slurries 12, 13, and 14. This indicates that the drilling fluid with added fiber plugging agent has a better plugging effect than the drilling fluid with added single sealant, walnut shell, and mica flakes.

[0132] This indicates that while adding three types of sealant—single sealant, walnut shell sealant, and mica sheet sealant—can reduce the penetration depth to varying degrees and achieve some sealing effect, it is far less effective than using fiber sealant simultaneously.

[0133] Test Example 2

[0134] This test example uses a GGS-42 high-temperature and high-pressure fluid loss meter to test the filtration loss of test slurries 10, 11, 12, 13, and 14 at 3.5 MPa and 120°C, which is the permeable water loss of the test slurry (a commonly used evaluation method in this field). This is used to analyze and compare the plugging performance of water-based drilling fluids with different plugging agents.

[0135] The test slurries were loaded into the high-temperature tank of the GGS-42 high-temperature and high-pressure water loss meter. The pressurization device was installed (without back pressure), and the temperature was raised to 120℃±3℃. The upper valve was opened, the pressure was adjusted to 3.5MPa, and the lower valve was opened. The time was set for 30 minutes, and the high-temperature and high-pressure filtration loss at 3.5MPa and 120℃±3℃ was measured. Then, the test slurry was slowly poured out. 10mL of distilled water was slowly added to the top of the slurry cup using a syringe. The test slurry on the top of the cake was gently shaken (3-4 times) without damaging the cake. The upper layer of washed test slurry was slowly poured out, leaving the cake. Distilled water was slowly refilled into the top of the slurry cup using a syringe, and the high-temperature and high-pressure filtration loss at 3.5MPa and 120℃±3℃ was measured again. This is the permeable water loss of the base slurry.

[0136] The invasion depth comparison of the test slurry 10 to the test slurry 14 is shown in Figure 2 As can be seen from Figure 2 , the test slurry 11 obtained by adding the fiber plugging agent in the embodiment 1 has the lowest water loss, and the water loss of the test slurry 11 is significantly less than that of the test slurry 12, the test slurry 13 and the test slurry 14. It shows that the plugging effect of the drilling fluid added with the fiber plugging agent is better than that of the drilling fluid added with the single seal, the walnut shell and the mica sheet.

[0137] Compared with the test slurry 10, although the three plugging agents of the single seal, the walnut shell and the mica sheet can reduce the invasion depth to different degrees and have a certain plugging effect, the plugging effect is far less than that of the fiber plugging agent.

[0138] Test Example 3

[0139] In this test example, the PPA sand disc filtration loss of the test slurry 10, the test slurry 11, the test slurry 12, the test slurry 13 and the test slurry 14 under 3.5 MPa and 120℃ is tested by using a permeability sealing instrument, that is, the sealing filtration loss (a commonly used evaluation method in the art). The plugging performance of the water-based drilling fluid added with different plugging agents is analyzed and compared. The sand disc specification is 210542, and the permeability is 13.5 Darcy.

[0140] The PPA sand disc filtration loss comparison of the test slurry 10 to the test slurry 14 is shown in Figure 3 As can be seen from Figure 3 , the test slurry 11 obtained by adding the fiber plugging agent in the embodiment 1 has the lowest PPA sand disc filtration loss, and the PPA sand disc filtration loss of the test slurry 11 is significantly less than that of the test slurry 12, the test slurry 13 and the test slurry 14. It shows that the plugging effect of the drilling fluid added with the fiber plugging agent is better than that of the drilling fluid added with the single seal, the walnut shell and the mica sheet.

[0141] Compared with the test slurry 10, although the three plugging agents of the single seal, the walnut shell and the mica sheet can reduce the invasion depth to different degrees and have a certain plugging effect, the plugging effect is far less than that of the fiber plugging agent.

[0142] Test Example 4

[0143] In this test example, the slot plate filtration loss of the test slurry 20 and the test slurry 21 under 5.0 MPa and 30 min is tested by using a QD-2 type drilling fluid plugging instrument, that is, the leakage loss (a commonly used evaluation method in the art). The plugging performance of the water-based drilling fluid added with different plugging agents on different crack sizes is analyzed and compared. The slot plates with slot widths of 1 mm, 2 mm, 3 mm and 5 mm are used for determination, and the selected slot plate is placed in the inner cavity of the plugging device.

[0144] 4000 mL of the prepared sample slurry was measured and injected into the plugging material device, the can lid was screwed tightly, the pressurizing pipeline was connected, it was left for 5 min, the discharge port was opened, the gas source was opened for pressurization, 0.7 MPa pressure was added first, the experimental slurry loss was collected, after stabilization, the pressure was increased by 0.5 MPa every 2 min, until the pressure was increased to 4 MPa, and the pressure was stabilized for 30 min, and the total sample slurry loss was read.

[0145] The loss amount comparison of the test slurry 20 and the test slurry 21 under different slit plate widths is shown in Figure 4 From Figure 4 it can be seen that the loss amount of the test slurry 20 obtained by adding the plugging agent with polyester fibers in Example 2 is obviously smaller than that of the test slurry 21 obtained by not adding the plugging agent with polyester fibers, and the difference between the two is greater as the slit plate width increases.

[0146] The test shows that for the crack type loss, the plugging effect of the plugging agent with polyester fibers is significantly higher than that of the plugging agent without fibers due to the tensile reinforcement effect of the fibers.

[0147] Test Example 5

[0148] This test example uses a QD-2 type drilling fluid plugging instrument to test the slit plate filtration loss of the test slurry 20 and the test slurry 21 under different pressures, i.e., the loss amount (a commonly used evaluation method in the art) under the condition of a 3 mm slit plate, 30 min. The plugging performance of water-based drilling fluids with different plugging agents under different pressure sizes is analyzed and compared. The selected 3 mm slit plate is placed in the inner cavity of the plugging device, and the pressure is determined by 2 MPa, 4 MPa, 6 MPa, and 8 MPa, respectively.

[0149] 4000 mL of the prepared sample slurry was measured and injected into the plugging material device, the can lid was screwed tightly, the pressurizing pipeline was connected, it was left for 5 min, the discharge port was opened, the gas source was opened for pressurization, 0.7 MPa pressure was added first, the experimental slurry loss was collected, after stabilization, the pressure was increased by 0.5 MPa every 2 min, until the pressure was increased to the set test pressure, and the pressure was stabilized for 30 min, and the total sample slurry loss was read.

[0150] The loss amount comparison of the test slurry 20 and the test slurry 22 under different pressures is shown in Figure 5 From Figure 5 it can be seen that the loss amount of the test slurry 20 obtained by adding the plugging agent with polyester fibers in Example 2 is obviously smaller than that of the test slurry 21 obtained by not adding the plugging agent with polyester fibers, and the difference between the two is greater as the slit plate width increases.

[0151] Experiments show that microporous aluminum foam particles have high hardness for crack-type leakage. With the addition of microporous aluminum foam particles, the pressure resistance of the sealant is greatly improved, and the sealing effect is significantly enhanced.

[0152] Test Example 6

[0153] This test example uses a QD-2 drilling fluid plugging instrument to test the filtration loss of test slurries 20 and 23 after hot rolling at different temperatures, under a 3mm wide slot plate, for 30 minutes, and a pressure of 4MPa. This is the leakage loss (a commonly used evaluation method in this field). This is used to analyze and compare the temperature resistance of water-based drilling fluids with different plugging agents. Hot rolling temperatures of 90℃, 120℃, 150℃, and 180℃ were used.

[0154] Measure 4000 mL of the hot-rolled sample slurry and inject it into the sealing material device. Tighten the cap, connect the pressurization line, let it stand for 5 minutes, open the discharge port, turn on the air source to pressurize, first apply a pressure of 0.7 MPa, collect the leakage of the test slurry, and after stabilization, increase the pressure by 0.5 MPa every 2 minutes until the pressure is increased to the set test pressure. Stabilize the pressure for 30 minutes and read the total leakage of the sample slurry.

[0155] The comparison of leakage of test slurry 20 and test slurry 23 after hot rolling is as follows: Figure 6 As shown. From Figure 6 As can be seen, the leakage of test slurry 20 obtained by adding polyester fiber, sepiolite fiber, wood fiber, jujube kernel particles and microporous aluminum foam particles in Example 2 is significantly less than that of test slurry 23 obtained by not adding polyester fiber, sepiolite fiber and microporous aluminum foam particles. In particular, the difference in leakage between the two increases with the increase of hot rolling temperature.

[0156] Experiments show that polyester fiber, sepiolite fiber, and microporous aluminum foam particles all possess good temperature resistance. Pouring agents using these three raw materials exhibit high temperature resistance. Under conditions of high bottom-hole temperature and pressure, plant fibers decompose rapidly and are prone to re-leaking, leading to frequent plugging during drilling operations, resulting in wasted time and materials. The plugging agent of this invention possesses superior temperature resistance, solving the problems of poor temperature resistance and easy decomposition and re-leaking associated with natural plant-based plugging agents.

[0157] Test Example 7

[0158] In this test, 400 mL of water was added to a beaker and stirred at 200 rpm using an electromagnetic stirrer. 4.0 g each of sealant 30, sealant 31, and sealant 32 were weighed and added to the beaker, and the time it took for each sealant to disperse into the water was recorded.

[0159] The dispersion of sealant 30, sealant 31, and sealant 32 is shown in Table 1.

[0160] Table 1 Dispersion time of the fiber plugging agent in water

[0161]

[0162] As can be seen from Table 1, the plugging agent 30 obtained by adding polyester fibers with a length-diameter ratio of 300-1000 in Example 4 has the lowest dispersion time in clean water, and the dispersion time is only 6s. The dispersion time of the plugging agent 31 is 45s, which is significantly longer than that of the plugging agent 30, and the dispersion time may cause the internal part of the rotary steering drilling tool to be stuck under the premise of using the rotary steering drilling tool. The plugging agent 32 cannot be dispersed and is gathered into a group, indicating that the dispersion effect of the fiber plugging agent drilling fluid is related to the length-diameter ratio of the fiber, and the larger the length-diameter ratio of the fiber, the worse the dispersion performance.

[0163] A too small length-diameter ratio may weaken the reinforcing effect of the fiber and thus reduce the plugging effect of the plugging agent, so the optimal length-diameter ratio of the fiber is 300-1000 under the premise of using the rotary steering drilling tool.

[0164] Example 4

[0165] As another preferred embodiment of the present application, the present embodiment discloses the application of the water-based drilling fluid high-dispersion fiber plugging agent in the above examples and comparative examples in the drilling operation with a rotary steering drilling tool.

[0166] Specifically, in the drilling operation with a rotary steering drilling tool, when loss occurs, the water-based drilling fluid high-dispersion fiber plugging agent is directly added to the water-based drilling fluid for plugging while drilling.

[0167] Further, the water-based drilling fluid high-dispersion fiber plugging agent is added to the water-based drilling fluid, and the water-based drilling fluid high-dispersion fiber plugging agent can pass through the internal gap of the rotary steering tool and will not block the rotary steering drilling tool.

[0168] First step: The mosaic plugging material rapidly enters the microfracture to form a preliminary plugging and quickly forms an internal plugging layer to rapidly reduce the invasion of filtrate into the rock formation. Second step: The film-forming plugging material performs micro-crosslinking deformable plugging on the basis of the mosaic particle layer to enhance the plugging strength and strengthen the plugging effect. The main technical index comparison is as follows:

[0169]

[0170] Before the domestic main exploration of shallow coalbed methane, the exploration of deep coalbed methane with a burial depth of more than 1500m has just started. In view of the coal seam collapse problem, the technical achievement is used to successfully complete the coal seam section construction of Nalin 1H well in 2022. The well depth is 5062m, and the layer is Benxi Formation 8# coal seam. The well wall is stable (the coal seam, carbonaceous mudstone and coal gangue drilled are not collapsed), and multiple records are broken. The technical indexes created by Nalin 1H well are as follows:

[0171] (1) The maximum vertical depth record of domestic deep coalbed methane horizontal well (3246m);

[0172] (2) The maximum well depth record of domestic deep coalbed methane horizontal well (5062m);

[0173] (3) The maximum displacement record of Changqing deep coalbed methane horizontal well (2071m);

[0174] (4) The longest horizontal section record of Changqing deep coalbed methane horizontal well (1500m);

[0175] (5) The longest safe period record of Changqing deep coalbed methane horizontal well (18 days);

[0176] (6) The maximum casing depth of Changqing deep coalbed methane horizontal well (5060.25m);

[0177] (7) The shortest drilling period of Changqing deep coalbed methane horizontal well (72 days).

[0178] The above is only a specific embodiment of the present application, and cannot limit the scope of the application. Therefore, the replacement of equivalent components or equivalent changes and modifications made within the scope of the present application should still belong to the scope of the present application. In addition, the technical features in the present application can be freely combined with each other, and the technical features can be freely combined with each other.

Claims

1. A highly dispersible fibrous lost circulation material for water-based drilling fluids, characterized in that: The lost circulation material comprises 10.0%-20.0% of high-dispersion high-aspect-ratio synthetic fibers; the high-dispersion high-aspect-ratio synthetic fibers are polyester fibers; the aspect ratio of the high-dispersion high-aspect-ratio synthetic fibers is 300-1000; 10.0%-40.0% of high-temperature-resistant natural fibers; the high-temperature-resistant natural fibers are any one or combination of sepiolite fibers and basalt fibers; the average length of the high-temperature-resistant natural fibers is 1.0 mm-3.0 mm; 10.0%-20.0% of wood fibers; 10.0%-30.0% of zizyphus jujuba mill. particles; the average particle size of the zizyphus jujuba mill. particles is 10 mesh-40 mesh 5.0%-10.0% of microporous aluminum foam particles; the average particle size of the microporous aluminum foam is 10 mesh-40 mesh, and the density is 1.0 g / cm 3 -1.3 g / cm 3 .

2. The high-dispersion fiber lost circulation material for water-based drilling fluid according to claim 1 is applied in drilling operation with a rotary steerable drilling tool.

3. The application method of the high-dispersible fiber plugging agent for water-based drilling fluid in the drilling operation with the rotary steering drilling tool according to claim 1, characterized in that: In the drilling operation with the rotary steerable drilling tool, when loss occurs, the water-based drilling fluid is not needed to be pulled out, and the high-dispersion fiber lost circulation material for water-based drilling fluid is directly added into the water-based drilling fluid for drilling plugging.

4. The application method of the high-dispersible fibrous plugging agent for water-based drilling fluid in the drilling operation with the rotary steering drilling tool according to claim 3, characterized in that: Under stirring conditions, the high-dispersion fiber lost circulation material for water-based drilling fluid is added into the water-based drilling fluid, and the high-dispersion fiber lost circulation material for water-based drilling fluid can pass through the internal gap of the rotary steerable tool without blocking the rotary steerable drilling tool.

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