An anti-collapse composition and fracture formation wellbore strengthening water-based drilling fluid

Abstract

The present invention provides an anti-collapse composition and a water-based drilling fluid for strengthening wellbore in fractured formations. The anti-collapse composition is composed of a high-temperature resistant anti-collapse agent HTFT, a modified asphalt anti-collapse agent GLA, and C9 petroleum resin. The water-based drilling fluid for strengthening wellbore in fractured formations provided by the present invention has the following advantages: ① strong inhibition and good filtration loss reduction performance; ② strong plugging performance and a wide effective plugging range, which can effectively plug cracks and pores in the range of submicron to 200 microns; ③ outstanding bonding ability, which can enhance the bonding force between broken rocks and maintain the stability of the wellbore wall; ④ strong rock-carrying ability, which can resist the high shear effect of the drill bit water hole, ensure the removal of rock cuttings and fallen blocks in the well section near the drill bit, and is used in drilling in fractured formations.

Description

Technical Field

[0001] The invention belongs to the technical field of tight sandstone oil and gas reservoir development, and in particular relates to an anti-collapse composition and a fractured formation wellbore strengthening water-based drilling fluid. Background Art

[0002] Fault bodies are controlled by the combined effects of faults and associated folds. Near faults (or zones), they form a network of fractured pores and reservoirs that are not distributed along a layered pattern, formed by the superposition of matrix pores associated with faults and folds. The development of large-scale matrix micropores and large-scale effective fracture communication are the primary factors in the formation of these reservoirs. Fault bodies have poor stratigraphic integrity, with wells and fractures, and are characterized by sequence anomalies, formation fragmentation, and pressure anomalies. Tight sandstone exploration and development targets fault bodies, and well deployment follows a "close-to-large fault" approach, penetrating small faults. This can lead to poor wellbore stability, resulting in block loss, drill bit burial, frequent lost circulation, and secondary well control risks. Prominent wellbore instability becomes a fatal weakness, posing extreme challenges to drilling operations.

[0003] To address the problem of wellbore instability in faulted formations, a variety of drilling fluid systems are currently in use, such as potassium-based polysulfone drilling fluid, composite salt-strongly inhibited polysulfone anti-collapse drilling fluid, and strong plugging oil-based drilling fluid. However, none of these can effectively solve the problem of wellbore instability in faulted formations. Therefore, it is necessary to develop a water-based drilling fluid system suitable for faulted formations. Summary of the Invention

[0004] A first aspect of the present invention provides an anti-collapse composition, which comprises a high-temperature resistant anti-collapse agent HTFT, a modified asphalt anti-collapse agent GLA and a C9 petroleum resin.

[0005] According to a specific embodiment of the present invention, the anti-collapse composition includes 10 to 20 parts by mass of the high temperature resistant anti-collapse agent HTFT, 10 to 20 parts by mass of the modified asphalt anti-collapse agent GLA and 10 to 25 parts by mass of the C9 petroleum resin.

[0006] According to a specific embodiment of the present invention, the particle size of the C9 petroleum resin is not greater than 80 mesh.

[0007] A second aspect of the present invention provides a water-based drilling fluid comprising a polyamine inhibitor SMJA-1, a plugging agent, an anti-collapse composition, a tackifier TQ-1, a fluid loss additive, bentonite, and water;

[0008] The anti-collapse composition is the anti-collapse composition described in the first aspect of the present invention.

[0009] According to a specific embodiment of the present invention, the water-based drilling fluid comprises 5 to 20 parts by mass of the polyamine inhibitor SMJA-1, 50 to 100 parts by mass of the plugging agent, 35 to 60 parts by mass of the anti-collapse composition, 10 to 20 parts by mass of the tackifier TQ-1, 50 to 80 parts by mass of the fluid loss additive, 30 to 60 parts by mass of the bentonite and 1000 parts by mass of water;

[0010] Preferably, the water-based drilling fluid comprises 5 to 20 parts by mass of the polyamine inhibitor SMJA-1, 50 to 100 parts by mass of the plugging agent, 35 to 60 parts by mass of the anti-collapse composition, 10 to 15 parts by mass of the viscosity enhancer TQ-1, 50 to 80 parts by mass of the fluid loss additive, 60 parts by mass of the bentonite and 1000 parts by mass of water.

[0011] According to a specific embodiment of the present invention, the plugging agent includes nano plugging agent NP-1, film-forming plugging agent FDM-1, ultrafine calcium carbonate and asphalt; and / or

[0012] The fluid loss additive comprises polyanionic cellulose, sulfonated phenolic resin and lignite resin SPNH for drilling fluid.

[0013] According to a specific embodiment of the present invention, the plugging agent includes 5 to 10 parts by mass of the nano plugging agent NP-1, 5 to 20 parts by mass of the film-forming plugging agent FDM-1, 20 to 50 parts by mass of the ultrafine calcium carbonate and 10 to 30 parts by mass of the asphalt;

[0014] and / or

[0015] The fluid loss additive comprises 10 to 20 parts by mass of the polyanionic cellulose, 20 to 40 parts by mass of the sulfonated phenolic resin, and 20 to 40 parts by mass of the lignite resin SPNH for drilling fluid;

[0016] Preferably, the plugging agent comprises 5 to 10 parts by mass of the nano plugging agent NP-1, 5 to 20 parts by mass of the film-forming plugging agent FDM-1, 25 to 50 parts by mass of the ultrafine calcium carbonate and 15 to 20 parts by mass of the asphalt;

[0017] and / or

[0018] The fluid loss additive includes 10 to 20 parts by mass of the polyanionic cellulose, 20 to 25 parts by mass of the sulfonated phenolic resin, and 20 to 35 parts by mass of the lignite resin SPNH for drilling fluid.

[0019] According to a specific embodiment of the present invention, the median particle size of the nano plugging agent NP-1 is 200 to 500 nm; and / or

[0020] The ultrafine calcium carbonate includes ultrafine calcium carbonate with an average particle size of 2500 meshes and ultrafine calcium carbonate with an average particle size of 1200 meshes; and / or

[0021] The average particle size of the asphalt is 7 to 100 μm;

[0022] Preferably, the ultrafine calcium carbonate comprises 10 to 25 parts by mass of ultrafine calcium carbonate having an average particle size of 2500 meshes and 10 to 30 parts by mass of ultrafine calcium carbonate having an average particle size of 1200 meshes; and / or

[0023] The average particle size of the asphalt is 6 to 80 μm;

[0024] Preferably, the ultrafine calcium carbonate comprises 15 to 25 parts by mass of ultrafine calcium carbonate having an average particle size of 2500 meshes and 10 to 25 parts by mass of ultrafine calcium carbonate having an average particle size of 1200 meshes; and / or

[0025] The sulfonated phenolic resin is sulfonated phenolic resin SMP-1.

[0026] According to a specific embodiment of the present invention, it is characterized in that the water-based drilling fluid further includes sodium carbonate and a lubricant;

[0027] Preferably, the amount of sodium carbonate used is 20 parts by mass; and / or the amount of the lubricant used is 10 parts by mass;

[0028] Preferably, the water-based drilling fluid further comprises a weighting agent; and / or

[0029] The weighting agent is barite; and / or

[0030] The density of the water-based drilling fluid is 1.2 g / cm 3 Up to 2g / cm 3 ;

[0031] Preferably, the lubricant is SRH-101.

[0032] According to a specific embodiment of the present invention, the water-based drilling fluid is prepared by the following method:

[0033] 1) mixing water and the bentonite, pre-hydrating, to obtain a base slurry;

[0034] 2) The polyamine inhibitor SMJA-1, the plugging agent, the anti-collapse composition, the tackifier TQ-1 and the fluid loss additive are mixed to obtain the water-based drilling fluid.

[0035] According to a specific embodiment of the present invention, in step 1), water, sodium carbonate and bentonite are mixed and then prehydrated; and / or

[0036] In step 2), the polyamine inhibitor SMJA-1, the plugging agent, the anti-collapse composition, the tackifier TQ-1, the fluid loss additive and the lubricant are mixed, and then a weighting agent is added and mixed to obtain the water-based drilling fluid;

[0037] Preferably, the temperature of the water is 60° C.; and / or the prehydration time is 24 hours;

[0038] Preferably, in step 1), the mixture is stirred at a speed of 600 r / min; and / or

[0039] In step 2), the mixture is stirred and mixed at a rotation speed of 5000 r / min.

[0040] The application of the anti-collapse composition according to the first aspect of the present invention and the water-based drilling fluid according to the second aspect of the present invention in the development of tight sandstone oil and gas reservoirs, especially in drilling in fractured formations.

[0041] The high temperature resistant anti-collapse agent HTFT of the present invention is purchased from Beijing Sanhe Runjing Technology Co., Ltd., and has a temperature resistance of 160°C;

[0042] The modified asphalt anti-collapse agent GLA of the present invention is purchased from Beijing Sanhe Runjing Technology Co., Ltd. and has a temperature resistance of 180°C;

[0043] The C9 petroleum resin of the present invention is obtained by crushing C9 petroleum resin particles with a softening point of 140° C. purchased from Jinan Dahui Chemical Technology Co., Ltd. using a grinder and passing the particles through an 80-mesh sieve.

[0044] The bentonite described in the present invention: bentonite for drilling fluid, purchased from Xinjiang Zhongfei Xiazijie Bentonite Co., Ltd.;

[0045] The polyamine inhibitor SMJA-1 described in the present invention was purchased from Jiujiang Lanzhuo New Material Technology Co., Ltd.

[0046] The nano plugging agent NP-1 of the present invention was purchased from Shak (Tianjin) Petroleum Technology Service Co., Ltd., with a D50 of 200 to 500 nm;

[0047] The film-forming plugging agent FDM-1 for drilling fluid of the present invention was purchased from Chengdu Xiyou Huawei Technology Co., Ltd.

[0048] The lignite resin SPNH for drilling fluid of the present invention was purchased from Chengdu Chuanfeng Chemical Engineering Co., Ltd.

[0049] The tackifier TQ-1 described in the present invention was purchased from Hongda Chemical Manufacturing Co., Ltd.

[0050] The lubricant SRH-101 described in the present invention was purchased from Tianjin Samit Chemical Co., Ltd.

[0051] Beneficial effects of the present invention:

[0052] To address the problems of existing drilling fluid systems used in drilling fractured formations, such as poor wellbore stability, poor suspension and rock-carrying properties, and insufficient clay mineral hydration inhibition and fractured rock cementation, the present invention provides an anti-collapse composition and a water-based drilling fluid for strengthening fractured formation wellbores. The anti-collapse composition comprises a high-temperature-resistant anti-collapse agent HTFT, a modified asphalt anti-collapse agent GLA, and C9 petroleum resin, and is capable of enhancing the cementation between fractured rocks under the influence of formation temperature and pressure. The water-based drilling fluid for strengthening fractured formation wellbores provided by the present invention primarily comprises a polyamine inhibitor SMJA-1, a plugging agent, the anti-collapse composition, a viscosity enhancer TQ-1, a fluid loss additive, bentonite, and water. Furthermore, it also comprises sodium carbonate, a lubricant, and a weighting agent. The plugging agent comprises a nano-plugging agent NP-1, a film-forming plugging agent FDM-1, ultrafine calcium carbonate with an average particle size of 2500 mesh, ultrafine calcium carbonate with an average particle size of 1200 mesh, and asphalt. In the fractured formation wellbore strengthening water-based drilling fluid, the anti-collapse composition and the plugging agent synergistically enhance each other, which is beneficial to improving the wellbore stability and wellbore strengthening performance of the fractured formation wellbore strengthening water-based drilling fluid: the high-temperature and high-pressure filtration loss (150°C, 3.5MPa) of the fractured formation wellbore strengthening water-based drilling fluid after hot rolling aging in a roller heating furnace at 150°C for 24 hours is 27.9 to 35.7mL; the fractured formation wellbore strengthening water-based drilling fluid blocks 50μm, 100μm, and 200μm cracks and leaks only in the pressure stabilization stage when the pressure reaches 3MPa to 3.5MPa. Before that, the plugging is successful, and for cracks in the submicron to 200μm range, the anti-collapse composition and the plugging agent synergistically enhance each other, which is beneficial to improving the wellbore stability and wellbore strengthening performance of the fractured formation wellbore strengthening water-based drilling fluid: the high-temperature and high-pressure filtration loss (150°C, 3.5MPa) of the fractured formation wellbore strengthening water-based drilling fluid is 27.9 to 35.7mL after hot rolling aging in a roller heating furnace at 150°C for 24 hours; the fractures in the fractured formation wellbore strengthening water-based drilling fluid block leakage only in the pressure stabilization stage when the pressure reaches 3MPa to 3.5MPa, and the plugging is successful before that. The fractures have a strong plugging ability; in a hot rolling test conducted after the fracture body formation wellbore reinforced water-based drilling fluid was hot-rolled and aged in a roller heating furnace at 150°C for 24 hours, the first rolling recovery rate of the Xujiahe outcrop core in the fracture body formation wellbore reinforced water-based drilling fluid was 95.18% to 98.53%; further, the second rolling recovery rate of the Xujiahe outcrop core in clean water after the first rolling recovery was still 87.29% to 95.11%; the rock samples soaked in the fracture body formation wellbore reinforced water-based drilling fluid have higher compressive strength and smaller needle penetration, specifically the compressive strength is 190.522 to 205.133KPa, and the needle penetration is 3.162 to 3.588mm. In summary, the water-based drilling fluid for strengthening the wellbore of the fractured formation provided by the present invention has the following advantages: ① strong inhibition and good filtration loss reduction performance; ② strong plugging ability and a wide effective plugging range, which can effectively plug cracks and pores in the range of submicron to 200 microns; ③ outstanding bonding ability, which can enhance the bonding force between broken rocks and maintain the stability of the well wall; ④ strong rock carrying capacity, which can resist the high shear effect of the drill bit water hole, ensure the removal of rock cuttings and fallen blocks in the near-drill bit well section, and is suitable for application in drilling in fractured formations. DETAILED DESCRIPTION

[0053] The present invention will be further described below with reference to examples. However, the examples are merely illustrative and do not limit the present invention in any way.

[0054] The polyanionic cellulose used in Examples 1 to 3 was purchased from Sichuan Mai Tewei New Materials Co., Ltd.

[0055] Example 1

[0056] The anti-collapse composition used in this embodiment includes 20g of high temperature resistant anti-collapse agent HTFT, 15g of modified asphalt anti-collapse agent GLA and 10g of C9 petroleum resin particles;

[0057] Preparation of water-based drilling fluid for fractured formation wellbore reinforcement:

[0058] Step 1: Measure 1000g of water, raise the water temperature to 60°C, add 60g of drilling fluid bentonite while stirring at 600r / min, stir for 30min, add 20g of Na2CO3 and continue stirring for 30min, and prehydrate at room temperature and pressure for 24h to obtain base slurry;

[0059] Step 2: Add 20 g of polyamine inhibitor SMJA-1 while stirring at a speed of 5000 r / min, and continue stirring for 30 minutes after the addition is completed;

[0060] Step 3: Add 10g of nano plugging agent NP-1, 10g of drilling fluid film-forming plugging agent FDM-1, 20g of ultrafine calcium carbonate with an average particle size of 2500 mesh, 20g of ultrafine calcium carbonate with an average particle size of 1200 mesh, and 20g of asphalt with an average particle size of 6 to 80μm while stirring at a speed of 5000r / min. Continue stirring for 30 minutes after the addition is completed;

[0061] Step 4: Add 45g of the anti-collapse composition while stirring at a speed of 5000r / min, and continue stirring for 30min after the addition is completed;

[0062] Step 5: Add 10 g of polyanionic cellulose, 20 g of sulfonated phenolic resin SMP-1, and 20 g of lignite resin SPNH for drilling fluid while stirring at a speed of 5000 r / min. Continue stirring for 30 minutes after the addition is completed;

[0063] Step 6: Add 10g of tackifier TQ-1 and 10g of lubricant SRH-101 while stirring at a speed of 5000r / min. Continue stirring for 30 minutes after the addition is complete.

[0064] Step 7: Add barite to adjust the system density to 1.5g / cm 3, and a water-based drilling fluid for strengthening the fracture formation wellbore was obtained, with a pH of 9.

[0065] Example 2

[0066] The anti-collapse composition used in this embodiment includes 15g of high temperature resistant anti-collapse agent HTFT, 20g of modified asphalt anti-collapse agent GLA and 25g of C9 petroleum resin particles;

[0067] Preparation of water-based drilling fluid for fractured formation wellbore reinforcement:

[0068] Step 1: Measure 1000g of water, raise the water temperature to 60°C, add 60g of drilling fluid bentonite while stirring at 600r / min, stir for 30min, add 20g of Na2CO3 and continue stirring for 30min, and prehydrate at room temperature and pressure for 24h to obtain base slurry;

[0069] Step 2: Add 5 g of polyamine inhibitor SMJA-1 while stirring at a speed of 5000 r / min, and continue stirring for 30 minutes after the addition is completed;

[0070] Step 3: Add 5g of nano plugging agent NP-1, 5g of drilling fluid film-forming plugging agent FDM-1, 15g of ultrafine calcium carbonate with an average particle size of 2500 mesh, 10g of ultrafine calcium carbonate with an average particle size of 1200 mesh, and 15g of asphalt with an average particle size of 6 to 80μm while stirring at a speed of 5000r / min. Continue stirring for 30 minutes after the addition is completed;

[0071] Step 4: Add 60g of the anti-collapse composition while stirring at a speed of 5000r / min, and continue stirring for 30min after the addition is completed;

[0072] Step 5: Add 20 g of polyanionic cellulose, 25 g of sulfonated phenolic resin SMP-1, and 35 g of lignite resin SPNH for drilling fluid while stirring at a speed of 5000 r / min, and continue stirring for 30 minutes after the addition is completed;

[0073] Step 6: Add 15g of tackifier TQ-1 and 10g of lubricant SRH-101 while stirring at a speed of 5000r / min. Continue stirring for 30 minutes after the addition is complete;

[0074] Step 7: Add barite to adjust the system density to 1.5g / cm 3 , and a water-based drilling fluid for strengthening the fracture formation wellbore was obtained, with a pH of 9.

[0075] Example 3

[0076] The anti-collapse composition used in this embodiment includes 10g of high temperature resistant anti-collapse agent HTFT, 10g of modified asphalt anti-collapse agent GLA and 15g of C9 petroleum resin particles;

[0077] Preparation of water-based drilling fluid for fractured formation wellbore reinforcement:

[0078] Step 1: Measure 1000g of water, raise the water temperature to 60°C, add 60g of drilling fluid bentonite while stirring at 600r / min, stir for 30min, add 20g of Na2CO3 and continue stirring for 30min, and prehydrate at room temperature and pressure for 24h to obtain base slurry;

[0079] Step 2: Add 15 g of polyamine inhibitor SMJA-1 while stirring at a speed of 5000 r / min, and continue stirring for 30 minutes after the addition is completed;

[0080] Step 3: Add 10g of nano plugging agent NP-1, 20g of drilling fluid film-forming plugging agent FDM-1, 25g of ultrafine calcium carbonate with an average particle size of 2500 mesh, 25g of ultrafine calcium carbonate with an average particle size of 1200 mesh, and 20g of asphalt with an average particle size of 6 to 80μm while stirring at a speed of 5000r / min. Continue stirring for 30 minutes after the addition is completed;

[0081] Step 4: Add 35g of the anti-collapse composition while stirring at a speed of 5000r / min, and continue stirring for 30min after the addition is completed;

[0082] Step 5: Add 15 g of polyanionic cellulose PAC, 20 g of sulfonated phenolic resin SMP-1, and 25 g of lignite resin SPNH for drilling fluid while stirring at a speed of 5000 r / min. Continue stirring for 30 minutes after the addition is completed;

[0083] Step 6: Add 15g of tackifier TQ-1 and 10g of lubricant SRH-101 while stirring at a speed of 5000r / min. Continue stirring for 30 minutes after the addition is complete;

[0084] Step 7: Add barite to adjust the system density to 1.5g / cm 3 , and a water-based drilling fluid for strengthening the fracture formation wellbore was obtained, with a pH of 9.

[0085] Experimental evaluation

[0086] 1. Basic performance evaluation of water-based drilling fluid for fractured formation wellbore reinforcement and determination of rolling recovery rate

[0087] The high-temperature and high-pressure filtration meter GGS42-2A from Kence Instruments (Shanghai) Co., Ltd. and the ZNN-D6B six-speed rotational viscometer from the Special Instrument Factory of Qingdao Hisense Optical Communication Co., Ltd. were used to measure the basic properties of the high-temperature and high-pressure filtration and rheological properties of the water-based drilling fluid for wellbore reinforcement in fractured formations. The rolling recovery rate was measured using the XGRL-2 digital roller heating furnace from the Special Instrument Factory of Qingdao Hisense Optical Communication Co., Ltd. and the LHG-2 aging tank from Kence Instruments (Shanghai) Co., Ltd. The specific steps are as follows:

[0088] 1) Determination of high-temperature and high-pressure filtration loss of reinforced water-based drilling fluid in fractured formation wellbore:

[0089] a. The fractured body formation wellbore enhanced water-based drilling fluid is added to the aging tank, and then the aging tank is placed in a roller heating furnace heated to 150°C for 24 hours to obtain the fractured body formation wellbore enhanced water-based drilling fluid after aging;

[0090] b. The aged drilling fluid obtained in step a was cooled to 60°C and then added to a high-temperature, high-pressure fluid loss meter GGS42-2A with a temperature set at 150°C and a pressure differential set at 3.5 MPa to measure the high-temperature, high-pressure fluid loss of the fractured formation wellbore after aging;

[0091] 2) Determination of basic properties such as rheology:

[0092] ⅰ. The fractured body wellbore strengthening water-based drilling fluid is added to the aging tank, and then the aging tank is placed in a roller heating furnace heated to 150 ° C for 24 hours to obtain the aged fractured body wellbore strengthening water-based drilling fluid;

[0093] ⅱ The aged fractured body obtained in step ⅰ was cooled to 60 ℃, and the rheological properties of the fractured body wellbore water-based drilling fluid were measured at 60 ℃ using a six-speed rotary viscometer ZNN-D6B after aging and strengthening the formation. Basic parameters such as the water-based drilling fluid;

[0094] 3) Rolling recovery rate determination:

[0095] A. Screen the Xujiahe outcrop core using a 6-10 mesh sieve, dry it at 105°C for 4 hours, and obtain the experimental rock chips, which are then placed in a desiccator for later use.

[0096] B. Pour 350 mL of fractured formation wellbore reinforced water-based drilling fluid into the aging tank, then add 50 g of rock cuttings while stirring to evenly disperse the rock cuttings in the fractured formation wellbore reinforced water-based drilling fluid. Immediately place the aging tank in a roller heating furnace heated to 150°C for 24 hours.

[0097] C. After the hot rolling is completed, immediately pour the hot-rolled fracture formation wellbore reinforced water-based drilling fluid carrying rock chips in the aging tank into a 40-mesh (0.425mm) sieve, place it in a water tank and rinse it repeatedly with water until the rinsed water is clear (if the rock chips are clumped together, gently separate them to disperse them into granules). Collect the rock chips after the hot rolling and place them in a 105℃ oven to dry for 4 hours. Place them in a desiccator to cool to room temperature and weigh them. Calculate the single rolling recovery rate R1 according to formula (1);

[0098]

[0099] Wherein, R1 is the one-time rolling recovery rate, %;

[0100] m1 is the mass of the rock chips after drying after rolling recovery, g;

[0101] m is the initial mass of cuttings, g.

[0102] D. The dried rock chips obtained after the first hot rolling in step C are passed through a 40-mesh sieve and weighed. The rock chips are dispersed into an aging tank filled with water at a mass volume ratio of 350 mL of water per 50 g of the dried rock chips after the first hot rolling. The aging tank is immediately placed in a roller heating furnace heated to 150°C for hot rolling for 16 hours. After the hot rolling is completed, the fracture formation wellbore reinforced water-based drilling fluid carrying rock chips in the aging tank is immediately poured into a 40-mesh (0.425 mm) sieve and placed in a water tank for repeated washing with water until the washed water is clear (if the rock chips are clumped together, gently separate them to disperse them into granules). The rock chips after the second hot rolling are collected and placed in a 105°C oven for drying for 4 hours. They are placed in a desiccator for cooling to room temperature and weighed. The secondary rolling recovery rate R2 is calculated according to formula (2);

[0103]

[0104] Wherein, R2 is the secondary rolling recovery rate, %;

[0105] m2 is the mass of the secondary rolling recovered cuttings after drying, g;

[0106] m3 is the mass of the residue after the rock chips are dried and sieved through a 40-mesh sieve, g.

[0107] According to the above method, the basic properties such as high temperature and high pressure fluid loss, rheological properties and rolling recovery of the fracture formation wellbore strengthening water-based drilling fluid prepared in Examples 1 to 3 were measured respectively. The specific results are shown in Table 1.

[0108] Table 1. Basic properties and rolling recovery rates of water-based drilling fluids for strengthening wellbore in fractured formations

[0109] index Example 1 Example 2 Example 3 <![CDATA[Φ 600 ]]> 112 107 115 <![CDATA[Φ 300 ]]> 79 75 80 Plastic viscosity (PV) / mPa.s 30 34 30 Dynamic shear force (YP) / Pa 21 24 22 <![CDATA[Initial shear force (G1) / Pa]]> 4 3 4 <![CDATA[Final cutting force (G2) / Pa]]> 9 9 10 <![CDATA[High Temperature High Pressure Fluid Loss (HTHP) 150℃ / mL]]> 29.3 35.7 27.9 One-time rolling recovery rate / % 98.53 95.18 98.21 Secondary rolling recovery rate / % 95.11 87.29 94.19

[0110] From the data in Table 1, it can be seen that the fracture formation wellbore reinforced water-based drilling fluid prepared in Examples 1 to 3 has good rheological energy and other basic properties. The high-temperature and high-pressure filtration loss (150°C, 3.5MPa) after hot rolling aging in a roller heating furnace at 150°C for 24 hours is 27.9 to 35.7mL, and the anti-filtration performance is good; in the hot rolling test of the fracture formation wellbore reinforced water-based drilling fluid prepared in Examples 1 to 3 after hot rolling aging in a roller heating furnace at 150°C for 24 hours, the Xujiahe outcrop core The primary rolling recovery rate in the fractured formation wellbore reinforced water-based drilling fluid is 95.18% to 98.53%; further, the secondary rolling recovery rate of the Xujiahe outcrop core in clean water after the primary rolling recovery is still 87.29% to 95.11%, indicating that the fractured formation wellbore reinforced water-based drilling fluid prepared in Examples 1 to 3 can effectively enhance the stability of the core surface, and the anti-collapse composition and the plugging agent therein synergistically enhance the effectiveness, and the fractured formation wellbore reinforced water-based drilling fluid has good wellbore stability improvement performance.

[0111] 2. Evaluation of the plugging performance of water-based drilling fluid in fractured formation wellbore reinforcement

[0112] The sealing performance of the fracture formation wellbore reinforced water-based drilling fluid prepared in Examples 1 to 3 on fractures of different widths was measured. The specific steps are as follows:

[0113] The 3D printer used in this experiment is the DesktopXLPlus 3D printer from EnvisionTEC, Germany.

[0114] (1) Preparation of cores with different fracture widths: rock samples made of polyphthalamide (PPA) were selected and cores with fracture widths of 50 μm, 100 μm, and 200 μm were prepared using a 3D printer;

[0115] (2) Plugging strength measurement: The prepared core with a specific fracture width was fixed in a core holder. Then, fracture body formation wellbore reinforced water-based drilling fluid was added to the core holder. The core holder was pressurized with a gradient at room temperature (specifically, starting from 0.5 MPa, pressurizing by 0.5 MPa every 5 minutes, and then pressurizing to 4 MPa and stabilizing for 5 minutes). The cumulative leakage was observed and recorded every 5 minutes before pressurization. The specific results are shown in Table 2.

[0116] Table 2. Plugging performance of water-based drilling fluid in fractured formation wellbore reinforcement

[0117]

[0118]

[0119]

[0120] Combined with the data and notes in Table 2, it can be seen that when the water-based drilling fluid for strengthening the wellbore of the fractured formation prepared in Example 1 is used to plug 50 μm cracks, 100 μm cracks, and 200 μm cracks, leakage only occurs during the steady pressure stage when the pressure reaches 3 MPa, 3.5 MPa, and 3.5 MPa respectively; when the water-based drilling fluid for strengthening the wellbore of the fractured formation prepared in Example 2 and Example 3 is used to plug 50 μm cracks, 100 μm cracks, and 200 μm cracks, leakage only occurs during the steady pressure stage when the pressure reaches 3 MPa. It can be seen that the reinforced water-based drilling fluid for the fractured formation wellbore prepared in Examples 1 to 3 only leaked during the pressure stabilization stage when the pressure reached 3 MPa to 3.5 MPa, and was successfully blocked before that. This shows that the reinforced water-based drilling fluid for the fractured formation wellbore prepared in Examples 1 to 3 can effectively block cracks of 50 μm, 100 μm, and 200 μm, and has a strong blocking ability for cracks in the submicron to 200 μm range.

[0121] 3. Evaluation of the Wellbore Strengthening Performance of Water-Based Drilling Fluids for Fault Formation Wellbore Strengthening

[0122] The rock samples of the Xujiahe Group II core material were immersed in conventional anti-collapse fault formation wellbore strengthening water-based drilling fluid and the fault formation wellbore strengthening water-based drilling fluid prepared in Examples 1 to 3, respectively. Their compressive strength was measured using a microporous electro-hydraulic servo concrete pressure testing machine produced by Shanghai Sansi Measuring Instrument Manufacturing Co., Ltd., and their penetration was measured using an intelligent needle penetration tester RP-2801B produced by Hebi Ruipu Instrument Co., Ltd., to evaluate the wellbore strengthening performance of the fault formation wellbore strengthening water-based drilling fluid.

[0123] The specific method is as follows:

[0124] The conventional anti-collapse fracture formation wellbore strengthening water-based drilling fluid used in this experiment includes 60g bentonite for drilling fluid, 40g soda ash, 4g quicklime, 5g polyamine inhibitor SMJA-1, 8g polyanionic cellulose, 20g sulfonated phenolic resin SMP-1, 20g lignite resin SPNH for drilling fluid, 1g zwitterionic polymer coating agent FA367, 40g lubricant SRH-101 and 1000mL water;

[0125] The zwitterionic polymer coating agent FA367 is a high molecular weight linear polymer containing cationic, anionic and nonionic groups, purchased from Puyang Meijing Chemical Materials Co., Ltd.

[0126] The core sample preparation machine used in this experiment is RHA-27640 core sample preparation machine, purchased from Beijing Runhengao Instrument Equipment Co., Ltd.

[0127] The microporous electro-hydraulic servo concrete pressure testing machine used in this experiment was purchased from Shanghai Sansi Measuring Instrument Manufacturing Co., Ltd.

[0128] The needle penetration tester used in this experiment: Intelligent needle penetration tester RP-2801B, purchased from Hebi Ruipu Instrument Co., Ltd.

[0129] ① Rock sample preparation: The cores of the second group of Xujiahe were crushed by a rock crusher and passed through 300-mesh, 240-mesh, and 80-mesh sieves to obtain core particles with particle sizes of 300-mesh, 240-mesh, and 80-mesh. The core particles of 300-mesh, 240-mesh, and 80-mesh were then mixed in a mass ratio of 3:3:4 and placed in a core sample preparation machine. The temperature was set to 100°C and the pressure was set to 50 MPa to prepare cylindrical rock samples with a length of 5 cm and a diameter of 2.54 cm. Several rock samples of the same specifications were prepared according to the above method for future use.

[0130] ② Control group: The prepared rock samples were immersed in conventional anti-collapse water-based drilling fluid for 12 hours. After being taken out, the water on the surface of the rock samples was absorbed with absorbent paper. The compressive strength was measured using a microporous electro-hydraulic servo concrete pressure testing machine at room temperature and normal pressure, and the penetration was measured using a needle penetration tester.

[0131] ③ Experimental group: Three prepared rock samples were taken and immersed in the fracture formation wellbore reinforced water-based drilling fluid prepared in Examples 1 to 3 for 12 hours, then taken out. The water on the surface of the rock samples was dried with absorbent paper, and the compressive strength was measured using a microporous electro-hydraulic servo concrete pressure testing machine at room temperature and normal pressure, and the penetration was measured using a needle penetration tester.

[0132] See Table 3 for specific results.

[0133] Table 3. Wellbore strengthening properties of water-based drilling fluid for wellbore strengthening in fractured formations

[0134] Serial number Compressive strength / KPa Needle penetration / mm control group 131.522 17.201 Example 1 201.377 3.162 Example 2 190.522 3.588 Example 3 205.133 3.211

[0135] Table 3 shows that the rock samples in the experimental group after being soaked in the fracture formation wellbore strengthening water-based drilling fluid prepared in Examples 1 to 3 have higher compressive strength and smaller penetration, with specific compressive strength of 190.522 to 205.133 kPa and penetration of 3.162 to 3.588 mm; while the rock samples of the same specifications in the control group after being soaked in the conventional anti-collapse fracture formation wellbore strengthening water-based drilling fluid have lower compressive strength and higher penetration, with specific compressive strength of only 131.522 kPa and penetration of up to 17.201 mm. The compressive strength of the rock samples in the experimental group after being soaked in the water-based drilling fluid for strengthening the fractured formation prepared in Examples 1 to 3 was 1.45 to 1.56 times that of the control group, while the penetration of the rock samples of the same specifications in the control group after being soaked in the conventional anti-collapse water-based drilling fluid for strengthening the fractured formation was 4.79 to 5.44 times that of the rock samples in the experimental group. This proves that the water-based drilling fluid for strengthening the fractured formation prepared in Examples 1 to 3 can effectively enhance the strength of the rock samples compared with the conventional anti-collapse water-based drilling fluid for strengthening the fractured formation. This indicates that the anti-collapse composition and the plugging agent in the water-based drilling fluid for strengthening the fractured formation prepared in Examples 1 to 3 synergistically enhance the effect, which helps to enhance the wellbore strengthening ability of the water-based drilling fluid for strengthening the fractured formation.

[0136] Based on the above experimental results, it can be seen that the fractured formation wellbore reinforced water-based drilling fluid prepared in Examples 1 to 3 has the following advantages: ① strong inhibition and good filtration loss reduction performance; ② strong plugging ability and a wide effective plugging range, which can effectively plug cracks and pores in the range of submicron to 200 microns; ③ outstanding bonding ability, which can enhance the bonding force between broken rocks and maintain the stability of the well wall; ④ strong rock carrying capacity, which can resist the high shear effect of the drill bit water hole, ensure the removal of rock cuttings and fallen blocks in the near-drill bit well section, and is suitable for application in fractured formation drilling.

[0137] Although the present invention has been described with reference to specific embodiments, it will be understood by those skilled in the art that various modifications may be made without departing from the true spirit and scope of the invention. Furthermore, the subject matter, spirit, and scope of the invention may be modified in various ways to adapt to specific circumstances, materials, material anti-collapse compositions, and methods. All such modifications are intended to be within the scope of the claims of the present invention.

Claims

1. An anti-collapse composition comprising a high-temperature resistant anti-collapse agent HTFT, a modified asphalt anti-collapse agent GLA and a C9 petroleum resin.

2. The anti-collapse composition according to claim 1, characterized in that The anti-collapse composition includes 10 to 20 parts by mass of the high-temperature resistant anti-collapse agent HTFT, 10 to 20 parts by mass of the modified asphalt anti-collapse agent GLA, and 10 to 25 parts by mass of the C9 petroleum resin.

3. The anti-collapse composition according to claim 1 or 2, characterized in that The particle size of the C9 petroleum resin is not greater than 80 meshes.

4. A water-based drilling fluid comprising a polyamine inhibitor SMJA-1, a plugging agent, an anti-collapse composition, a tackifier TQ-1, a fluid loss additive, bentonite, and water; The anti-collapse composition is the anti-collapse composition according to any one of claims 1 to 3.

5. The water-based drilling fluid according to claim 4, characterized in that: The water-based drilling fluid includes 5 to 20 parts by mass of the polyamine inhibitor SMJA-1, 50 to 100 parts by mass of the plugging agent, 35 to 60 parts by mass of the anti-collapse composition, 10 to 20 parts by mass of the viscosity enhancer TQ-1, 50 to 80 parts by mass of the fluid loss additive, 30 to 60 parts by mass of the bentonite and 1000 parts by mass of water.

6. The water-based drilling fluid according to claim 4 or 5, characterized in that: The plugging agent includes nano plugging agent NP-1, film-forming plugging agent FDM-1, ultrafine calcium carbonate and asphalt; and / or The fluid loss additive comprises polyanionic cellulose, sulfonated phenolic resin and lignite resin SPNH for drilling fluid.

7. The water-based drilling fluid according to claim 6, characterized in that: The plugging agent comprises 5 to 10 parts by mass of the nano plugging agent NP-1, 5 to 20 parts by mass of the film-forming plugging agent FDM-1, 20 to 50 parts by mass of the ultrafine calcium carbonate and 10 to 30 parts by mass of the asphalt; and / or The fluid loss additive includes 10 to 20 parts by mass of the polyanionic cellulose, 20 to 40 parts by mass of the sulfonated phenolic resin, and 20 to 40 parts by mass of the lignite resin SPNH for drilling fluid.

8. The water-based drilling fluid according to claim 6, characterized in that: The median particle size of the nano plugging agent NP-1 is 200 to 500 nm; and / or The ultrafine calcium carbonate includes ultrafine calcium carbonate with an average particle size of 2500 meshes and ultrafine calcium carbonate with an average particle size of 1200 meshes; and / or The average particle size of the asphalt is 7 to 100 μm.

9. The water-based drilling fluid according to claim 8, characterized in that: The ultrafine calcium carbonate includes 10 to 25 parts by mass of ultrafine calcium carbonate with an average particle size of 2500 meshes and 10 to 30 parts by mass of ultrafine calcium carbonate with an average particle size of 1200 meshes.

10. The water-based drilling fluid according to claim 4 or 5, characterized in that: The water-based drilling fluid also includes sodium carbonate and a lubricant.

11. The water-based drilling fluid according to claim 10, characterized in that: The amount of the sodium carbonate used is 20 parts by mass; and / or the amount of the lubricant used is 10 parts by mass.

12. The water-based drilling fluid according to claim 4 or 5, characterized in that: The water-based drilling fluid further comprises a weighting agent; and / or The weighting agent is barite; and / or The density of the water-based drilling fluid is 1.2 g / cm 3 Up to 2g / cm 3 .

13. Use of the anti-collapse composition according to any one of claims 1 to 3 or the water-based drilling fluid according to any one of claims 4 to 12 in the development of tight sandstone oil and gas reservoirs.

14. The use according to claim 13, characterized in that The application is application in drilling in fractured formations.

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