A polycyclic polymer viscosity increasing and filtration reducing agent for temperature and salt resistant drilling fluid and its preparation method and application

Abstract

The present invention provides a polycyclic polymer viscosity-enhancing fluid loss reducer for temperature-resistant and salt-resistant drilling fluid and its preparation method and application, belonging to the field of drilling technology. The viscosity-enhancing fluid loss reducer of the present invention includes the following raw materials in parts by mass: 8-10 parts of 2-acrylamido-2-methylpropanesulfonic acid, 15-17 parts of acrylamide, 4-6 parts of diallyldimethylammonium chloride, 2-4 parts of 1,8-ethylenenaphthalene, 9-13 parts of octavinyl POSS, 0.1-0.2 parts of initiator, 0.1-0.2 parts of Span 80, 0.1-0.2 parts of Tween 80, and 80-120 parts of deionized water. The viscosity-enhancing fluid loss reducer of the present invention can effectively reduce the drilling fluid loss, increase the drilling fluid viscosity and maintain the rheological stability of the drilling fluid under high temperature and high salt conditions, and can be applied to oil and gas drilling in deep high-salt formations.

Description

Technical Field

[0001] The invention belongs to the technical field of drilling, and in particular relates to a multi-ring polymer viscosity increasing and fluid loss reducing agent for temperature and salt resistant drilling fluid, and a preparation method and application thereof. Background Art

[0002] my country's deep and ultra-deep reservoirs are rich in oil and natural gas resources. The exploration of deep and ultra-deep oil and gas is the only way for the future development of oil and gas. The depth of these deep reservoirs generally exceeds 6000m, the bottom hole temperature is high, and the salt-gypsum layer is widely distributed, which puts higher requirements on the temperature and salt resistance of the drilling fluid. As an important additive to drilling fluid, filtrate reducers play a key role in safe, rapid and efficient drilling. However, the current filtrate reducers are difficult to meet the requirements of high temperature and salt resistance in deep well drilling. At the same time, under high temperature and high salt conditions, the filtrate reducers are prone to degradation and curling, resulting in a significant decrease in the viscosity of the drilling fluid, which seriously affects the drilling fluid's ability to maintain well wall stability, carry cuttings and suspend weighting materials, and cause major safety accidents such as well kicks and blowouts. Therefore, it is necessary to improve the performance of water-based drilling fluid filtrate reducers at high temperature and high salt (Na + , K + , Ca 2+ ) conditions and fluid loss reduction performance are crucial for safe and efficient drilling in deep formations.

[0003] There are many patent literature reports on fluid loss reducers. For example, Chinese patent document CN111303356A discloses a non-sulfonated temperature-resistant fluid loss reducer, which has good filter reduction performance at room temperature and 180℃~200℃, but its temperature resistance needs to be further improved. Chinese patent document CN114989351A discloses a low molecular weight fluid loss reducer for drilling fluid, which has a temperature resistance of 200℃ and a saturated salt resistance, but the ester monomer is easily degraded at high temperature, and the temperature resistance of the polymer needs to be improved. Chinese patent document CN106432632A discloses a calcium salt-resistant amino polymer fluid loss reducer, which is resistant to 180℃, but has a low viscosity after hot rolling under high temperature and high salt conditions. Chinese patent document CN115850578A discloses a polymer fluid loss reducer, which is resistant to temperature up to 230℃, but has a salt resistance of only 4%, and its salt resistance needs to be improved. Chinese patent document CN116082570A discloses a nano-composite fluid loss reducer that can withstand temperatures up to 240°C in fresh water, but its salt and calcium resistance needs to be further improved.

[0004] Therefore, it is urgent to develop a temperature-resistant and salt-resistant (Na + , K + , Ca 2+ ) Excellent performance viscosity increasing and fluid loss reducing agent to meet the requirements of ultra-deep well drilling. Summary of the invention

[0005] Aiming at the deficiencies of the prior art, especially the shortcomings of the existing polymer fluid loss reducers for water-based drilling fluids: poor temperature resistance, easy degradation and loss of function in high-temperature environments of deep and ultra-deep formations; poor salt resistance, and the fluid loss reduction effect of the drilling fluid system is greatly reduced when drilling into deep salt-gypsum layers; under high temperature and high salt conditions, the curling and aggregation of polymer molecular chains significantly reduce the viscosity of the drilling fluid. The present invention provides a multi-ring polymer viscosity-enhancing fluid loss reducer for temperature-resistant and salt-resistant drilling fluids, and a preparation method and application thereof. The viscosity-enhancing fluid loss reducer of the present invention can effectively reduce the filtration loss of drilling fluids, increase the viscosity of drilling fluids and maintain the rheological stability of drilling fluids under high temperature and high salt conditions, can withstand temperatures above 220°C, resist NaCl concentrations of up to 36wt%, resist KCl concentrations of up to 5.0wt%, and resist CaCl2 concentrations of up to 3.0wt%, and can be applied to oil and gas drilling in deep high-salt formations.

[0006] The present invention is achieved through the following technical solutions:

[0007] A polycyclic polymer viscosity increasing and fluid loss reducing agent for temperature and salt resistant drilling fluid is prepared by comprising the following raw materials in parts by weight: 8-10 parts of 2-acrylamido-2-methylpropanesulfonic acid, 15-17 parts of acrylamide, 4-6 parts of diallyldimethylammonium chloride, 2-4 parts of 1,8-ethylenenaphthalene, 9-13 parts of octavinyl POSS, 0.1-0.2 parts of initiator, 0.1-0.2 parts of Span 80, 0.1-0.2 parts of Tween 80 and 80-120 parts of deionized water.

[0008] Preferably, the polycyclic polymer viscosity increasing and filtration reducing agent for temperature and salt resistant drilling fluid is prepared by including the following raw materials in parts by weight: 9 parts of 2-acrylamido-2-methylpropanesulfonic acid, 16 parts of acrylamide, 5 parts of diallyldimethylammonium chloride, 2-4 parts of 1,8-ethylenenaphthalene, 9-13 parts of octavinyl POSS, 0.15 parts of initiator, 0.15 parts of Span 80, 0.15 parts of Tween 80, and 100 parts of deionized water.

[0009] Preferably according to the present invention, the initiator is azobisisobutyramidine hydrochloride.

[0010] The preparation method of the above-mentioned multi-ring polymer viscosity increasing and fluid loss reducing agent for temperature and salt resistant drilling fluid comprises the steps of:

[0011] (1) 1,8-ethylenenaphthalene, Span 80 and Tween 80 are fully mixed and emulsified to obtain emulsion A;

[0012] (2) Add 2-acrylamido-2-methylpropanesulfonic acid to deionized water, adjust the pH to 7-8, then add acrylamide, diallyldimethylammonium chloride, and octavinyl POSS, and stir until fully dispersed; add emulsion A and initiator, stir to react, and then wash, dry, and crush to obtain a polycyclic polymer viscosity-enhancing and fluid loss reducer for temperature-resistant and salt-resistant drilling fluid.

[0013] Preferably, according to the present invention, in step (2), a NaOH aqueous solution with a mass fraction of 30%-40% is used to adjust the pH of the system to 7-8.

[0014] Preferably, according to the present invention, in step (2), the reaction temperature is 65-75° C. and the reaction time is 4-6 h.

[0015] Preferably, in step (2), washing is performed using acetone; and drying is performed at 80-100° C. for 20-30 hours.

[0016] The above-mentioned multi-ring polymer viscosity increasing and filtration reducing agent for temperature-resistant and salt-resistant drilling fluid is used in drilling reservoirs at a depth of 6000-9000m.

[0017] Preferably, according to the present invention, the polycyclic polymer viscosity increasing and fluid loss reducing agent for temperature and salt resistant drilling fluid is added to the drilling fluid at a concentration of 1-5wt%.

[0018] The technical features and beneficial effects of the present invention are as follows:

[0019] 1. The polycyclic polymer viscosity increasing and filtration reducing agent for temperature-resistant and salt-resistant drilling fluid of the present invention is a polycyclic strong rigid polymer viscosity increasing and filtration reducing agent for drilling fluid prepared by emulsion polymerization of 2-acrylamido-2-methylpropanesulfonic acid, acrylamide, diallyldimethylammonium chloride, 1,8-ethylenenaphthalene, and octavinyl POSS monomer. The polycyclic polymer viscosity increasing and filtration reducing agent for temperature-resistant and salt-resistant drilling fluid of the present invention has an NaCl concentration resistance of 36wt%, a KCl concentration resistance of 5wt%, and a CaCl2 concentration resistance of 3wt% at 220°C, and has excellent high temperature and salt resistance performance.

[0020] 2. The rigid groups used in the multi-ring strong rigid polymer viscosity increasing and fluid loss reducing agent for anti-ultra-high temperature and high salt drilling fluid of the present invention, such as naphthyl and its derivatives, increase the rigidity of the chain segments in the polymer chain. This rigidity limits the movement and vibration of the molecular chain at high temperature, reduces the possibility of segment breakage, and when the polymer is heated, the movement of the molecular chain intensifies, and the presence of the rigid group can resist this movement, thereby improving the ability of the polymer to resist thermal deformation and thermal decomposition. The increase in polymer rigidity makes the polymer more resistant to ion penetration and swelling in a saline environment, thereby improving the salt resistance of the polymer. The rigid group occupies a large space in the polymer molecular chain, forming a steric effect. This steric effect reduces the contact and collision of the chain segments at high temperatures, further reducing the risk of segment breakage. The steric effect can also prevent the occurrence of some chemical reactions that may cause polymer degradation, thereby improving the thermal stability of the polymer. At the same time, the steric effect can hinder the diffusion and penetration of salt ions inside the polymer, reducing the influence of salt ions on polymer properties, thereby improving the salt resistance of the polymer. At the same time, the introduction of rigid groups can avoid the appearance of weak bonds and unstable structures in the polymer chain to a certain extent, which are easy to break at high temperatures, causing the polymer to degrade, thus affecting the viscosity of the drilling fluid. On the contrary, rigid groups tend to form more stable chemical bonds and molecular structures, improving the stability of the polymer at high temperatures and the viscosity of the drilling fluid.

[0021] 3. 1,8-ethylenenaphthalene is added to the multi-ring strong rigid polymer viscosity increasing and filtration reducing agent for ultra-high temperature and high salt drilling fluid of the present invention. The aromatic benzene ring of the monomer provides hydrophobic properties and rigidity, thereby improving the thermal stability of the polymer; the cyclic functional group has a steric hindrance effect, and there is no need to add a chain transfer agent, which can not only control the molecular weight of the polymer itself, but also reduce the synthesis cost; at the same time, the naphthyl group can make the spatial structure formed by the polymer not easy to deform, curl up and fail under high temperature and high pressure conditions.

[0022] 4. Octavinyl POSS is added to the polycyclic strong rigid polymer viscosity increasing and filtration reducing agent for ultra-high temperature and high salt drilling fluid of the present invention. Cage-shaped oligomeric silsesquioxane (POSS) is a very stable organic / inorganic hybrid nanomaterial with an inorganic core of Si-O-Si structure. The core is composed of a silicon oxygen skeleton alternately connected by Si-O, and the shape is like a "cage", which can significantly enhance the rigidity of the polymer molecular chain. The increase in this rigidity restricts the movement of the molecular chain when the polymer is subjected to external stress or temperature changes, reduces the movement of the chain segment, and reduces the possibility of chain segment breakage, thereby improving the stability of the polymer. The rigid group occupies a large space in the polymer molecular chain, forming a steric effect. This steric effect can hinder the diffusion and penetration of salt ions inside the polymer, reduce the influence of salt ions on the performance of the polymer, and thus improve the salt resistance of the polymer. At the same time, the octavinyl POSS itself has a spatial network structure, which can improve the viscosity of the drilling fluid under high temperature and high salt conditions. The three-dimensional size of this monomer is between 1 and 3 nm, and it is called the "smallest silicon oxide structure". The special structure makes the POSS particles have extremely high thermal stability, structural designability, nanosize effect, good compatibility, environmental protection and non-toxicity, and good solubility.

[0023] 5. The components of the fluid loss reducer of the present invention work together in a specific ratio to achieve the excellent effect of the present invention, that is, the fluid loss reducer of the present invention has excellent fluid loss reduction performance under ultra-high temperature and high salt conditions, meeting the drilling requirements of high temperature and high salt formations. The lack of any component, the inappropriate type of raw materials and the inappropriate ratio of raw materials will reduce the performance of the fluid loss reducer. DETAILED DESCRIPTION

[0024] The present invention is further described below in conjunction with specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0025] Unless otherwise specified, the reagents, materials and equipment used in the examples can be obtained from commercial sources; the experimental methods described below are all conventional methods unless otherwise specified.

[0026] Example 1

[0027] A polycyclic polymer viscosity increasing and fluid loss reducing agent for temperature-resistant and salt-resistant drilling fluid is prepared by comprising the following raw materials in parts by weight: 9 parts of 2-acrylamido-2-methylpropanesulfonic acid, 16 parts of acrylamide, 5 parts of diallyldimethylammonium chloride, 2 parts of 1,8-ethylenenaphthalene, 9 parts of octavinyl POSS, 0.15 parts of initiator azobisisobutylamidine hydrochloride, 0.15 parts of Span 80, 0.15 parts of Tween 80, and 100 parts of deionized water.

[0028] The preparation method of the polycyclic polymer viscosity increasing and fluid loss reducing agent for temperature-resistant and salt-resistant drilling fluid comprises the following steps: mixing 1,8-ethylenenaphthalene with Spann 80 and Tween 80, and then putting the mixture into a stirring and dispersing machine for stirring for 20 minutes to emulsify the 1,8-ethylenenaphthalene, and fully emulsify the monomers to fully disperse the monomers, thereby obtaining emulsion A; adding 2-acrylamido-2-methylpropanesulfonic acid to deionized water, adjusting the pH to 7 using a 35% mass fraction NaOH aqueous solution, and then adding acrylamide, diallyldimethylammonium chloride, and octavinyl POSS, and stirring until fully dispersed; adding emulsion A, and then heating to 70°C, adding an initiator, and performing emulsion polymerization and stirring reaction for 4 hours to obtain a viscous polymer crude product; washing the polymer crude product with acetone twice, drying at 85°C for 24 hours, and crushing it with a crusher (15 seconds at a time, and crushing it 4 times) to obtain a white powder, namely the polycyclic polymer viscosity increasing and fluid loss reducing agent A1 for temperature-resistant and salt-resistant drilling fluid.

[0029] Example 2

[0030] A polycyclic polymer viscosity increasing and fluid loss reducing agent for temperature and salt resistant drilling fluid is as described in Example 1, except that octavinyl POSS is changed to 11 parts; other raw material compositions are the same as those in Example 1.

[0031] The preparation method of the polycyclic polymer viscosity increasing and fluid loss reducing agent for temperature-resistant and salt-resistant drilling fluid is as described in Example 1, and the polycyclic polymer viscosity increasing and fluid loss reducing agent A2 for temperature-resistant and salt-resistant drilling fluid is obtained.

[0032] Example 3

[0033] A polycyclic polymer viscosity increasing and fluid loss reducing agent for temperature and salt resistant drilling fluid is as described in Example 1, except that 1,8-ethylenenaphthalene is changed to 3 parts; the other raw material compositions are the same as those in Example 1.

[0034] The preparation method of the polycyclic polymer viscosity increasing and fluid loss reducing agent for temperature-resistant and salt-resistant drilling fluid is as described in Example 1, and the polycyclic polymer viscosity increasing and fluid loss reducing agent A3 for temperature-resistant and salt-resistant drilling fluid is obtained.

[0035] Example 4

[0036] A polycyclic polymer viscosity increasing and fluid loss reducing agent for temperature and salt resistant drilling fluid is as described in Example 1, except that octavinyl POSS is changed to 13 parts; and the other raw material compositions are the same as those in Example 1.

[0037] The preparation method of the polycyclic polymer viscosity increasing and fluid loss reducing agent for temperature-resistant and salt-resistant drilling fluid is as described in Example 1, and the polycyclic polymer viscosity increasing and fluid loss reducing agent A4 for temperature-resistant and salt-resistant drilling fluid is obtained.

[0038] Example 5

[0039] A polycyclic polymer viscosity increasing and fluid loss reducing agent for temperature and salt resistant drilling fluid is as described in Example 1, except that 1,8-ethylenenaphthalene is replaced by 4 parts; the other raw material compositions are the same as those in Example 1.

[0040] The preparation method of the polycyclic polymer viscosity increasing and fluid loss reducing agent for temperature-resistant and salt-resistant drilling fluid is as described in Example 1, and the polycyclic polymer viscosity increasing and fluid loss reducing agent A5 for temperature-resistant and salt-resistant drilling fluid is obtained.

[0041] Example 6

[0042] A polycyclic polymer viscosity increasing and fluid loss reducing agent for temperature and salt resistant drilling fluid is prepared by comprising the following raw materials in parts by weight: 8 parts of 2-acrylamido-2-methylpropanesulfonic acid, 15 parts of acrylamide, 4 parts of diallyldimethylammonium chloride, 2 parts of 1,8-ethylenenaphthalene, 9 parts of octavinyl POSS, 0.1 parts of initiator azobisisobutylamidine hydrochloride, 0.1 parts of Span 80, 0.1 parts of Tween 80 and 80 parts of deionized water.

[0043] The preparation method of the polycyclic polymer viscosity increasing and fluid loss reducing agent for temperature-resistant and salt-resistant drilling fluid is as described in Example 1, and the polycyclic polymer viscosity increasing and fluid loss reducing agent A6 for temperature-resistant and salt-resistant drilling fluid is obtained.

[0044] Example 7

[0045] A polycyclic polymer viscosity increasing and fluid loss reducing agent for temperature and salt resistant drilling fluid is prepared by comprising the following raw materials in parts by weight: 10 parts of 2-acrylamido-2-methylpropanesulfonic acid, 17 parts of acrylamide, 6 parts of diallyldimethylammonium chloride, 2 parts of 1,8-ethylenenaphthalene, 9 parts of octavinyl POSS, 0.2 parts of initiator azobisisobutylamidine hydrochloride, 0.2 parts of Span 80, 0.2 parts of Tween 80 and 120 parts of deionized water.

[0046] The preparation method of the polycyclic polymer viscosity increasing and fluid loss reducing agent for temperature-resistant and salt-resistant drilling fluid is as described in Example 1, and the polycyclic polymer viscosity increasing and fluid loss reducing agent A7 for temperature-resistant and salt-resistant drilling fluid is obtained.

[0047] Comparative Example 1

[0048] A fluid loss reducer, as described in Example 1, except that: octavinyl POSS is changed to 7 parts; other raw material compositions are the same as in Example 1.

[0049] The preparation method of the polycyclic polymer viscosity increasing and fluid loss reducing agent for temperature-resistant and salt-resistant drilling fluid is as described in Example 1, and the polycyclic polymer viscosity increasing and fluid loss reducing agent D1 for temperature-resistant and salt-resistant drilling fluid is obtained.

[0050] Comparative Example 2

[0051] A fluid loss reducer, as described in Example 1, except that 1,8-ethylenenaphthalene is replaced by 1 part; the other raw material compositions are the same as those in Example 1.

[0052] The preparation method of the polycyclic polymer viscosity increasing and fluid loss reducing agent for temperature-resistant and salt-resistant drilling fluid is as described in Example 1, and the polycyclic polymer viscosity increasing and fluid loss reducing agent D2 for temperature-resistant and salt-resistant drilling fluid is obtained.

[0053] Comparative Example 3

[0054] A fluid loss reducer, as described in Example 1, except that 1,8-ethylenenaphthalene is replaced by maleic anhydride; other raw material compositions are the same as in Example 1.

[0055] The preparation method of the above-mentioned fluid loss reducer is as described in Example 1, except that the difference is the same as above, and the fluid loss reducer D3 is obtained.

[0056] Comparative Example 4

[0057] A fluid loss reducer is as described in Example 1, except that 1,8-ethylenenaphthalene is not added; other raw material compositions are the same as in Example 1.

[0058] The preparation method of the above-mentioned fluid loss reducer is as described in Example 1, except that the difference is the same as above, and the fluid loss reducer D4 is obtained.

[0059] Comparative Example 5

[0060] A fluid loss reducer is as described in Example 1, except that octavinyl POSS is not added; other raw material compositions are the same as in Example 1.

[0061] The preparation method of the above-mentioned fluid loss reducer is as described in Example 1, except that the difference is the same as above, and the fluid loss reducer D5 is obtained.

[0062] Comparative Example 6

[0063] A fluid loss reducer is as described in Example 1, except that 1,8-ethylenenaphthalene is replaced by 2-vinylnaphthalene; and the other raw material compositions are the same as those in Example 1.

[0064] The preparation method of the above-mentioned fluid loss reducer is as described in Example 1, except that the difference is the same as above, and the fluid loss reducer D6 is obtained.

[0065] Comparative Example 7

[0066] A fluid loss reducer, as described in Example 1, except that: the amount of 2-acrylamido-2-methylpropanesulfonic acid is 10 parts, the amount of acrylamide is 25 parts, and the amount of octavinyl POSS is 3 parts; other raw material compositions are the same as in Example 1.

[0067] The preparation method of the above-mentioned fluid loss reducer is as described in Example 1, except that the difference is the same as above, and the fluid loss reducer D7 is obtained.

[0068] Comparative Example 8

[0069] A fluid loss reducer, as described in Example 1, except that diallyldimethylammonium chloride is not added; other raw material compositions are the same as in Example 1.

[0070] The preparation method of the above-mentioned fluid loss reducer is as described in Example 1, except that the difference is the same as above, and the fluid loss reducer D8 is obtained.

[0071] Comparative Example 9

[0072] A fluid loss reducer, as described in Example 1, except that diallyldimethylammonium chloride is replaced by acryloyloxyethyltrimethylammonium chloride; and the other raw material compositions are the same as in Example 1.

[0073] The preparation method of the above-mentioned fluid loss reducer is as described in Example 1, except that the difference is the same as above, and the fluid loss reducer D9 is obtained.

[0074] Comparative Example 10

[0075] A fluid loss reducer, as described in Example 1, except that diallyldimethylammonium chloride and 1,8-ethylenenaphthalene are not added; other raw material compositions are the same as those in Example 1.

[0076] The preparation method of the above-mentioned fluid loss reducing agent is as described in Example 1, except that the above-mentioned fluid loss reducing agent D is obtained. 10 .

[0077] Application Examples

[0078] 1. Drilling fluid F1: 4 parts by weight of sodium bentonite were added to 100 parts of water, stirred at high speed for 20 minutes and then allowed to stand at room temperature for 24 hours. The bentonite slurry was stirred for another 20 minutes, and 3 parts of the fluid loss reducer A1 prepared in Example 1 were added, and the mixture was fully mixed and dispersed evenly.

[0079] 2. Drilling fluid F2: 4 parts by weight of sodium bentonite were added to 100 parts of water, stirred at high speed for 20 minutes and then allowed to stand at room temperature for 24 hours. The bentonite slurry was stirred for another 20 minutes, 3 parts of the fluid loss reducer A1 prepared in Example 1 were added, and then NaCl (accounting for 36 wt % of the bentonite slurry) was added, and the mixture was fully mixed and dispersed evenly.

[0080] 3. Drilling fluid F3: 4 parts by weight of sodium bentonite were added to 100 parts of water, stirred at high speed for 20 minutes and then allowed to stand at room temperature for 24 hours. The bentonite slurry was stirred for another 20 minutes, 3 parts of the fluid loss reducer A1 prepared in Example 1 and KCl (accounting for 5 wt% of the bentonite slurry) were added, and the mixture was fully mixed and dispersed evenly.

[0081] 4. Drilling fluid F4: Add 4 parts by weight of sodium bentonite to 100 parts of water, stir at high speed for 20 minutes and then stand at room temperature for 24 hours. Stir the bentonite slurry for another 20 minutes, add 3 parts of the fluid loss reducer A1 prepared in Example 1, add CaCl2 (accounting for 3wt% of the bentonite slurry), mix well and disperse evenly.

[0082] 5. Drilling fluid F5: 4 parts by weight of sodium bentonite were added to 100 parts of water, stirred at high speed for 20 minutes and then allowed to stand at room temperature for 24 hours. The bentonite slurry was stirred for another 20 minutes, 3 parts of the fluid loss reducer A2 prepared in Example 2 were added, and then NaCl (accounting for 36 wt % of the bentonite slurry) was added, and the mixture was fully mixed and dispersed evenly.

[0083] 6. Drilling fluid F6: 4 parts by weight of sodium bentonite were added to 100 parts of water, stirred at high speed for 20 minutes and then allowed to stand at room temperature for 24 hours. The bentonite slurry was stirred for another 20 minutes, 3 parts of the fluid loss reducer A2 prepared in Example 2 and KCl (accounting for 5 wt% of the bentonite slurry) were added, and the mixture was fully mixed and dispersed evenly.

[0084] 7. Drilling fluid F7: Add 4 parts by weight of sodium bentonite to 100 parts of water, stir at high speed for 20 minutes and then stand at room temperature for 24 hours. Stir the bentonite slurry for another 20 minutes, add 3 parts of the fluid loss reducer A2 prepared in Example 2, add CaCl2 (accounting for 3wt% of the bentonite slurry), mix well and disperse evenly.

[0085] 8. Drilling fluid F8: 4 parts by weight of sodium bentonite were added to 100 parts of water, stirred at high speed for 20 minutes and then allowed to stand at room temperature for 24 hours. The bentonite slurry was stirred for another 20 minutes, 3 parts of the fluid loss reducer A3 prepared in Example 3 were added, and then NaCl (accounting for 36 wt % of the bentonite slurry) was added, and the mixture was fully mixed and dispersed evenly.

[0086] 9. Drilling fluid F9: Add 4 parts by weight of sodium bentonite to 100 parts of water, stir at high speed for 20 minutes and then stand at room temperature for 24 hours. Stir the bentonite slurry for another 20 minutes, add 3 parts of the fluid loss reducer A3 prepared in Example 3, add KCl (accounting for 5 wt% of the bentonite slurry), mix well and disperse evenly.

[0087] 10. Drilling fluid F10: Add 4 parts by weight of sodium bentonite to 100 parts of water, stir at high speed for 20 minutes and then stand at room temperature for 24 hours. Stir the bentonite slurry for another 20 minutes, add 3 parts of the fluid loss reducer A3 prepared in Example 3, add CaCl2 (accounting for 3wt% of the bentonite slurry), mix well and disperse evenly.

[0088] 11. Drilling fluid F11: 4 parts by weight of sodium bentonite were added to 100 parts of water, stirred at high speed for 20 minutes and then allowed to stand at room temperature for 24 hours. The bentonite slurry was stirred for another 20 minutes, 3 parts of the fluid loss reducer A4 prepared in Example 4 were added, and NaCl (accounting for 36 wt % of the bentonite slurry) was added, and the mixture was fully mixed and dispersed evenly.

[0089] 12. Drilling fluid F12: Add 4 parts by weight of sodium bentonite to 100 parts of water, stir at high speed for 20 minutes and then stand at room temperature for 24 hours. Stir the bentonite slurry for another 20 minutes, add 3 parts of the fluid loss reducer A5 prepared in Example 5, add NaCl (accounting for 36 wt% of the bentonite slurry), mix well and disperse evenly.

[0090] 13. Drilling fluid F13: 4 parts by weight of sodium bentonite were added to 100 parts of water, stirred at high speed for 20 minutes and then allowed to stand at room temperature for 24 hours. The bentonite slurry was stirred for another 20 minutes, 3 parts of the fluid loss reducer A6 prepared in Example 6 and NaCl (accounting for 36 wt% of the bentonite slurry) were added, and the mixture was thoroughly mixed and dispersed evenly.

[0091] 14. Drilling fluid F14: 4 parts by weight of sodium bentonite were added to 100 parts of water, stirred at high speed for 20 minutes and then allowed to stand at room temperature for 24 hours. The bentonite slurry was stirred for another 20 minutes, 3 parts of the fluid loss reducer A7 prepared in Example 7 and NaCl (accounting for 36 wt% of the bentonite slurry) were added, and the mixture was thoroughly mixed and dispersed evenly.

[0092] 15. Drilling fluid DF1: Add 4 parts by weight of sodium bentonite to 100 parts of water, stir at high speed for 20 minutes, then stand and cure at room temperature for 24 hours, and stir the bentonite slurry for another 20 minutes.

[0093] 16. Drilling fluid DF2: Add 4 parts by weight of sodium bentonite to 100 parts of water, stir at high speed for 20 minutes, then stand and cure at room temperature for 24 hours. Stir the bentonite slurry for another 20 minutes, add NaCl (36wt% of the bentonite slurry), mix thoroughly and disperse evenly.

[0094] 17. Drilling fluid DF3: Add 4 parts by weight of sodium bentonite to 100 parts of water, stir at high speed for 20 minutes, then stand and cure at room temperature for 24 hours. Stir the bentonite slurry for another 20 minutes, add KCl (accounting for 5wt% of the bentonite slurry), mix thoroughly and disperse evenly.

[0095] 18. Drilling fluid DF4: Add 4 parts by weight of sodium bentonite to 100 parts of water, stir at high speed for 20 minutes, then stand and cure at room temperature for 24 hours. Stir the bentonite slurry for another 20 minutes, add CaCl2 (3wt% of the bentonite slurry), mix thoroughly and disperse evenly.

[0096] 19. Drilling fluid DF5: Add 4 parts by weight of sodium bentonite to 100 parts of water, stir at high speed for 20 minutes and then stand at room temperature for 24 hours. Stir the bentonite slurry for another 20 minutes, add 3 parts of the filtrate reducer D1 prepared in Comparative Example 1, add NaCl (accounting for 36wt% of the bentonite slurry), mix well and disperse evenly.

[0097] 20. Drilling fluid DF6: Add 4 parts by weight of sodium bentonite to 100 parts of water, stir at high speed for 20 minutes and then stand at room temperature for 24 hours. Stir the bentonite slurry for another 20 minutes, add 3 parts of the filtration reducer D2 prepared in Comparative Example 2, add NaCl (accounting for 36wt% of the bentonite slurry), mix well and disperse evenly.

[0098] 21. Drilling fluid DF7: Add 4 parts by weight of sodium bentonite to 100 parts of water, stir at high speed for 20 minutes and then stand at room temperature for 24 hours. Stir the bentonite slurry for another 20 minutes, add 3 parts of the filtration reducer D3 prepared in Comparative Example 3, add NaCl (accounting for 36wt% of the bentonite slurry), mix well and disperse evenly.

[0099] 22. Drilling fluid DF8: Add 4 parts by weight of sodium bentonite to 100 parts of water, stir at high speed for 20 minutes and then stand at room temperature for 24 hours. Stir the bentonite slurry for another 20 minutes, add 3 parts of filtration reducer D4 prepared in Comparative Example 4, add NaCl (accounting for 36wt% of the bentonite slurry), mix well and disperse evenly.

[0100] 23. Drilling fluid DF9: Add 4 parts by weight of sodium bentonite to 100 parts of water, stir at high speed for 20 minutes and then stand at room temperature for 24 hours. Stir the bentonite slurry for another 20 minutes, add 3 parts of the filtration reducer D5 prepared in Comparative Example 5, add NaCl (accounting for 36wt% of the bentonite slurry), mix well and disperse evenly.

[0101] 24. Drilling fluid DF10: Add 4 parts by weight of sodium bentonite to 100 parts of water, stir at high speed for 20 minutes and then stand at room temperature for 24 hours. Stir the bentonite slurry for another 20 minutes, add 3 parts of filtration reducer D6 prepared in Comparative Example 6, add NaCl (accounting for 36wt% of the bentonite slurry), mix well and disperse evenly.

[0102] 25. Drilling fluid DF11: Add 4 parts by weight of sodium bentonite to 100 parts of water, stir at high speed for 20 minutes and then stand at room temperature for 24 hours. Stir the bentonite slurry for another 20 minutes, add 3 parts of filtration reducer D7 prepared in Comparative Example 7, add NaCl (accounting for 36wt% of the bentonite slurry), mix well and disperse evenly.

[0103] 26. Drilling fluid DF12: Add 4 parts by weight of sodium bentonite to 100 parts of water, stir at high speed for 20 minutes and then stand at room temperature for 24 hours. Stir the bentonite slurry for another 20 minutes, add 3 parts of filtration reducer D8 prepared in Comparative Example 8, add NaCl (accounting for 36wt% of the bentonite slurry), mix well and disperse evenly.

[0104] 27. Drilling fluid DF13: Add 4 parts by weight of sodium bentonite to 100 parts of water, stir at high speed for 20 minutes and then stand at room temperature for 24 hours. Stir the bentonite slurry for another 20 minutes, add 3 parts of filtration reducer D9 prepared in Comparative Example 9, add NaCl (accounting for 36 wt% of the bentonite slurry), mix well and disperse evenly.

[0105] 28. Drilling fluid DF14: 4 parts by weight of sodium bentonite were added to 100 parts of water, stirred at high speed for 20 minutes, and then allowed to stand at room temperature for 24 hours. The bentonite slurry was stirred for another 20 minutes, and 3 parts of the fluid loss reducer D prepared in Comparative Example 10 were added. 10 , add NaCl (accounting for 36wt% of bentonite slurry), mix thoroughly and disperse evenly.

[0106] 29. Drilling fluid DF15: Add 4 parts by weight of sodium bentonite to 100 parts of water, stir at high speed for 20 minutes, then stand and cure at room temperature for 24 hours. Stir the bentonite slurry for another 20 minutes, add 3 parts of high temperature and salt resistance filtration reducer DSP-1, add NaCl (accounting for 36wt% of the bentonite slurry), mix thoroughly and disperse evenly.

[0107] 30. Drilling fluid DF16: Add 4 parts by weight of sodium bentonite to 100 parts of water, stir at high speed for 20 minutes, then stand and cure at room temperature for 24 hours. Stir the bentonite slurry for another 20 minutes, add 3 parts of high temperature and salt resistant filtration reducer Driscal D, add NaCl (accounting for 36wt% of the bentonite slurry), mix thoroughly and disperse evenly.

[0108] 31. Drilling fluid DF17: Add 4 parts by weight of sodium bentonite to 100 parts of water, stir at high speed for 20 minutes, then stand and cure at room temperature for 24 hours. Stir the bentonite slurry for another 20 minutes, add 3 parts of high temperature and salt resistant filtration reducer SMP-II, add NaCl (accounting for 36wt% of the bentonite slurry), mix thoroughly and disperse evenly.

[0109] Test Example 1

[0110] Take 400mL of drilling fluid F1-F14 and DF1-DF17 and stir them at 8000rpm for 20min, then put them into a stainless steel aging tank and roll them at a constant temperature of 220℃ for 16 hours. After aging, cool them to room temperature and take them out, and stir them at 8000rpm for 20min. According to the petroleum and natural gas industry standard GB / T 29170-2012 "Petroleum and Natural Gas Industry-Drilling Fluid Laboratory Test", the apparent viscosity (AV, mPa·s), plastic viscosity (PV, mPa·s), dynamic shear force (YP, Pa), API filtration loss FL of the above drilling fluids were measured. API , high temperature and high pressure filtration loss FL HTHP (220℃, 3.45MPa), the results are shown in Tables 1 and 2.

[0111] Table 1 Drilling fluid performance test

[0112]

[0113] Table 2 Drilling fluid performance test

[0114]

[0115] From the experimental results of F1-F4 and DF1-DF4, it is known that after adding 3% of the fluid loss reducer of the present invention, the API fluid loss of fresh water base slurry can be reduced from 48.0mL to 5.0mL, and the high temperature and high pressure fluid loss can be reduced from 113.0mL to 26.8mL. The API fluid loss of drilling fluid DF2 after high temperature aging is as high as 256.0mL, and FL HTHP Total filtration loss; DF3 API and FL HTHP Total filtration loss; the API filtration loss of the drilling fluids F2, F3 and F4 added with the filtration reducer of the present invention after high-temperature aging were 5.6mL, 5.8mL and 9.6mL respectively, and the high-temperature and high-pressure filtration loss were 36.6mL, 32.4mL and 39.6mL respectively; the apparent viscosity of the drilling fluid added with the filtration reducer of the present invention after high-temperature aging increased significantly, and the drilling fluids F2, F3 and F4 were 31.0mPa·s, 31.5mPa·s and 28.0mPa·s respectively, and the apparent viscosity of the drilling fluids DF2, DF3 and DF4 without the filtration reducer of the present invention after high-temperature aging were 6.5mPa·s, 10.5mPa·s and 5.0mPa·s respectively.

[0116] From the test results of F2-F4, F5-F7 and F11, it can be seen that appropriately increasing the proportion of octavinyl POSS in the polymer can further reduce the filtration loss and increase the viscosity of the drilling fluid. Because octavinyl POSS is a very stable organic / inorganic hybrid nanomaterial, it can be evenly dispersed in the polymer matrix. This nano-scale dispersion allows a large number of interfaces to be formed between POSS particles and polymer chains, thereby enhancing the interaction between polymer chains. This interaction force can form a stable cross-linked network in the drilling fluid, thereby effectively improving the viscosity of the drilling fluid. At the same time, the inorganic core with Si-O-Si structure, the POSS particles with its special structure enhance the rigidity of the polymer and improve the overall thermal stability of the polymer. On the contrary, from the experimental results of DF5, it is known that reducing the proportion of octavinyl POSS in the polymer will reduce the composition of the silicon-oxygen skeleton connected alternately by Si-O, and the polymer rigidity will be reduced, resulting in insufficient temperature and salt resistance of the polymer.

[0117] From the test results of F2-F4, F8-F10 and F12, it can be seen that appropriately increasing the proportion of 1,8-ethylenenaphthalene in the monomer can also reduce the fluid loss. More aromatic benzene rings provide hydrophobic properties and rigidity for the polymer, thereby improving the thermal stability of the polymer; the π electron cloud density of the aromatic benzene ring is large, which makes its molecules have a strong interaction force. In the drilling fluid, this interaction may promote the aggregation and cross-linking of the drilling fluid molecules, thereby increasing the viscosity of the drilling fluid. From the test results of DF6 and DF11, it can be seen that reducing the proportion of 1,8-ethylenenaphthalene in the polymer will also lead to a decrease in the fluid loss reduction performance of the polymer. Because the benzene ring content in the polymer is reduced, the high temperature resistance of the polymer is weakened. However, when the proportion of 1,8-ethylenenaphthalene monomer is further increased, due to the steric effect of the benzene ring of the 1,8-ethylenenaphthalene monomer, the excessive number will hinder the polymerization between the monomers. The polymerization result is that the reaction product has a low molecular weight, low viscosity, or even cannot be polymerized, and has poor fluid loss reduction performance; if the proportion of 1,8-ethylenenaphthalene in the monomer is too high, the proportion of other groups such as sulfonic acid groups will decrease, which will also weaken the adsorption, temperature resistance and salt resistance of the polymer, resulting in an increase in fluid loss. Therefore, the proportion of 1,8-ethylenenaphthalene needs to be controlled within the scope of the present invention, at which time the polymerization effect of 1,8-ethylenenaphthalene monomer and other monomers is good, and the fluid loss reduction performance is excellent.

[0118] It can be seen from the test results of DF7 that when 1,8-ethylenenaphthalene is replaced by maleic anhydride, the fluid loss reduction performance and viscosity are significantly reduced. This is because the thermal decomposition temperature of the polymer fluid loss reducer synthesized by maleic anhydride is low. During high-temperature drilling, it is easy to thermally decompose and generate small molecular substances, thereby losing its original fluid loss reduction and viscosity increasing functions.

[0119] From the test results of DF8-DF9, it can be seen that when 1,8-ethylenenaphthalene or octavinyl POSS is not added, the fluid loss reduction performance decreases, because the rigid groups are reduced, the thermal stability of the fluid loss reducer is reduced, the molecular chains are destroyed under high temperature conditions, the fluid loss amount increases, the interaction force between molecules decreases, and the viscosity of the drilling fluid decreases.

[0120] From the test results of F1-F14, DF1-DF4, DF5-DF9, it can be seen that the performance of the viscosity increasing and fluid loss reducing agent of the present invention is reduced after being added to 36% NaCl, 5% KCl, and 3% CaCl2, but it can still remain stable within a certain range; compared with the 36% NaCl, 5% KCl, and 3% CaCl2 salt slurry without adding fluid loss reducing agent, the fluid loss is significantly reduced, and the apparent viscosity, plastic viscosity, and dynamic shear force are significantly improved. From the experimental results, it can be seen that due to the presence of rigid groups in 1,8-ethylenenaphthalene and octavinyl POSS, while enhancing the thermal stability of the polymer, the rigid strength of the side chain of the polymer molecule can be enhanced. The molecule is not easy to curl up or deform in a high temperature and high salt environment, and can still stretch in water to form a spatial structure to increase the viscosity of the drilling fluid.

[0121] From the test results of DF10, it can be seen that when 1,8-ethylenenaphthalene is replaced by 2-vinylnaphthalene, the fluid loss reduction performance decreases, because the vinyl group in 1,8-ethylenenaphthalene is connected between the 1st and 8th positions of the naphthalene ring to form a special conjugated structure, which is more rigid and thermally stable than 2-vinylnaphthalene.

[0122] From the test results of DF13, it can be seen that when diallyl dimethyl ammonium chloride is replaced by acryloyloxyethyl trimethyl ammonium chloride, the viscosity decreases and the filtration loss reduction performance decreases slightly. This is because the thermal stability of the two is similar, but diallyl dimethyl ammonium chloride can provide two sites for reaction, and the spatial grid structure formed by the polymerization reaction is more complex and has higher strength.

[0123] From the test results of DF12 and DF14, it can be seen that without adding diallyldimethylammonium chloride, diallyldimethylammonium chloride and 1,8-ethylenenaphthalene, the filtration loss reduction performance and viscosity are significantly reduced, because the reduction of quaternary ammonium salt groups and rigid groups reduces the adsorption amount of the polymer on the surface of the viscosity particles and the thermal stability under high temperature and high salt conditions.

[0124] From the experimental results of DF15, DF16 and DF17, it is known that under the condition of 36% NaCl, the API filtration loss of the drilling fluid after high temperature aging with 3% DSP-1, DriscalD and SMP-II is 9.8mL, 14.6mL and 80.4mL respectively, and the high temperature and high pressure filtration loss is 63.8mL, 55.2mL and 230.0mL respectively. The API filtration loss of the drilling fluid with the filtration loss reducer of the present invention under the same conditions is 5.6mL, and the high temperature and high pressure filtration loss is 36.6mL. The apparent viscosity of DSP-1, DriscalD and SMP-II after aging is 10.5mPa·s, 10.0mPa·s and 11.5mPa·s respectively, and the apparent viscosity of the drilling fluid with the filtration loss reducer of the present invention under the same conditions is 31.0mPa·s. The viscosity-increasing filtration loss reducer of the present invention can increase the viscosity of the drilling fluid while providing excellent filtration loss reduction performance for the drilling fluid, and its performance is better than similar oilfield commonly used products.

[0125] In summary, the multi-ring strong rigid polymer viscosity increasing and filtration reducer for ultra-high temperature and high salt resistant drilling fluid of the present invention has a temperature resistance of up to 220°C, a NaCl resistance of 36%, a KCl resistance of 5%, and a CaCl2 resistance of 3%. It has excellent filtration reduction performance under high temperature and high salt conditions and meets the drilling needs of deep wells with high temperature and high salt formations.

[0126] The preferred embodiments of the fluid loss reducer of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0127] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0128] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A polycyclic polymer viscosity increasing and fluid loss reducing agent for temperature and salt resistant drilling fluid, characterized in that: The invention is prepared by the following raw materials in parts by weight: 8-10 parts of 2-acrylamido-2-methylpropanesulfonic acid, 15-17 parts of acrylamide, 4-6 parts of diallyldimethylammonium chloride, 2-4 parts of 1,8-ethylenenaphthalene, 9-13 parts of octavinyl POSS, 0.1-0.2 parts of initiator, 0.1-0.2 parts of Span 80, 0.1-0.2 parts of Tween 80 and 80-120 parts of deionized water.

2. The multi-ring polymer viscosity increasing and fluid loss reducing agent for temperature and salt resistant drilling fluid according to claim 1, characterized in that: The polycyclic polymer viscosity increasing and fluid loss reducing agent for temperature and salt resistant drilling fluid is prepared by including the following raw materials in parts by weight: 9 parts of 2-acrylamido-2-methylpropanesulfonic acid, 16 parts of acrylamide, 5 parts of diallyldimethylammonium chloride, 2-4 parts of 1,8-ethylenenaphthalene, 9-13 parts of octavinyl POSS, 0.15 parts of initiator, 0.15 parts of Span 80, 0.15 parts of Tween 80 and 100 parts of deionized water.

3. The multi-ring polymer viscosity increasing and fluid loss reducing agent for temperature and salt resistant drilling fluid according to claim 1, characterized in that: The initiator is azobisisobutyramidine hydrochloride.

4. The method for preparing the temperature-resistant and salt-resistant multi-ring polymer viscosity-increasing and fluid loss reducing agent for drilling fluid according to any one of claims 1 to 3, comprising the steps of: (1) 1,8-ethylenenaphthalene, Span 80 and Tween 80 are fully mixed and emulsified to obtain emulsion A; (2) Add 2-acrylamido-2-methylpropanesulfonic acid to deionized water, adjust the pH to 7-8, then add acrylamide, diallyldimethylammonium chloride, and octavinyl POSS, and stir until fully dispersed; add emulsion A and initiator, stir to react, and then wash, dry, and crush to obtain a polycyclic polymer viscosity-enhancing and fluid loss reducer for temperature-resistant and salt-resistant drilling fluid.

5. The method for preparing the temperature-resistant and salt-resistant multi-ring polymer viscosity-increasing and fluid loss reducing agent for drilling fluid according to claim 4, characterized in that: In step (2), a 30%-40% by mass NaOH aqueous solution is used to adjust the pH of the system to 7-8.

6. The method for preparing the temperature-resistant and salt-resistant multi-ring polymer viscosity-increasing and fluid loss reducing agent for drilling fluid according to claim 4, characterized in that: In step (2), the reaction temperature is 65-75°C and the reaction time is 4-6h.

7. The method for preparing the temperature-resistant and salt-resistant multi-ring polymer viscosity-increasing and fluid loss reducing agent for drilling fluid according to claim 4, characterized in that: In step (2), washing is performed using acetone; and drying is performed at 80-100° C. for 20-30 hours.

8. The use of the multi-ring polymer viscosity increasing and fluid loss reducing agent for temperature and salt resistance drilling fluid as claimed in any one of claims 1 to 3 in reservoir drilling at a depth of 6000 to 9000 m, characterized in that: The concentration of the polycyclic polymer viscosity increasing and fluid loss reducing agent for temperature and salt resistant drilling fluid added to the drilling fluid is 1-5wt%.

Images