Multi-series organic salt efficient water-based drilling fluid and preparation method thereof

Abstract

The invention relates to the technical field of drilling operation, in particular to a multi-series organic salt efficient water-based drilling fluid and a preparation method thereof.The drilling fluid comprises, by weight, 100 parts of solvent water, 3-4 parts of a shear strength improving agent, 0.12-0.16 part of anhydrous sodium carbonate, 2-5.5 parts of a filtrate reducer, 2-5 parts of a plugging anti-collapse agent, 1-3 parts of a lubricant inhibitor, 5-90 parts of a soluble weighting agent and 5-346 parts of an inert weighting agent. The preparation method is simple and is prepared by sequentially adding the shear strength improving agent, the filtrate reducer, the plugging anti-collapse agent, the inhibiting lubricant and the weighting agent into the solvent under high-speed stirring. The adding time and the adding amount of the soluble weighting agent are adjusted according to different densities of the prepared drilling fluid, so that the stable performance of the drilling fluid is ensured. The drilling fluid has the advantages of formation density of 1.20-2.44 g / cm < 3 >, multi-serialization of 150-200 DEG C temperature resistance, wide application range and stable performance, forms a database in a template form for field engineers to flexibly select according to production requirements, saves production time, reduces well control risks, and realizes unification of economic benefits and social benefits.

Description

Technical Field

[0001] The present invention relates to the technical field of oil, natural gas, and coalbed methane drilling operations, and particularly relates to a multi-series organic salt-based high-efficiency water-based drilling fluid and a preparation method thereof. Background Art

[0002] As an important branch of water-based drilling fluids, organic salt drilling fluids have become internationally recognized high-efficiency and low-toxic drilling fluid systems because of their stable performance, strong anti-pollution and inhibition and anti-collapse capabilities, which have better resolved the contradiction between wellbore stability and protection of oil and gas reservoirs. They are widely used at home and abroad and have achieved very good application results. At present, there are many organic salt drilling fluid systems and supporting products at home and abroad, but the applicable density and temperature ranges are limited and no series has been formed. During the application process, engineers need to continuously adjust the formula and performance of the drilling fluid system according to the on-site situation and their own experience, which not only increases the workload, but also increases the uncertainty of the application effect and the well control risk. There are no reports in the literature or on the market for organic salt drilling fluid systems, supporting products, and technologies with a wide application range, high cost performance, and a database formed by multi-series for on-site engineers to use as a template.

[0003] The published patent CN 201710680508.4 discloses a strongly inhibitory organic salt drilling fluid, and its formula is: 500 mL of fresh water + 0.5% Na 2 CO 3 + 6% Xiazijie clay + 3% Redu2 + 0.7% NAT20 + 0.1% IND30 + 3% NFA-25 + 2% PGCS-1 + 5% strongly inhibitory organic salt + 10 g of ultrafine calcium carbonate + 150 g of barite. The density of this drilling fluid system is about 1.30 g / cm 3 or so, the apparent viscosity after aging at 150 °C / 16 h is about 25 mPa·s, and the high-temperature and high-pressure filtration loss is about 11 mL.

[0004] The published paper "Organic Salt Drilling Fluid Technology" (Exploration of Western China) discloses an organic salt drilling fluid system with a density of 1.18 - 2.60 g / cm 3 . After aging at 150 °C / 16 h, the apparent viscosity is 32.5 - 124 mPa·s, and the high-temperature and high-pressure filtration loss is 12 - 18 mL; for the system with a density of 1.46 / cm 3 , after aging at 200 °C / 16 h, the apparent viscosity is 40.5 mPa·s, and the high-temperature and high-pressure filtration loss is 18.5 mL; the resistance to bentonite, sodium chloride, and gypsum pollution reaches 5%, 4%, and 1% respectively. "Research and Application of Organic Salt Drilling Fluids" (Petroleum Drilling Techniques) discloses an organic salt drilling fluid system with a density of 1.20 - 2.42 g / cm 3The organic salt drilling fluid system has a plastic viscosity of 27 - 100 mPa·s, an API filtration loss of 0.8 - 4.0 mL, and a high-temperature and high-pressure filtration loss of 6.5 - 15.5 mL before aging; for some systems, the plastic viscosity is 20 - 97 mPa·s, and the API filtration loss is 0.8 - 4.0 mL after aging at 120°C for 16 h; the resistance to bentonite and gypsum contamination reaches 7.5% and 1% respectively.

[0005] The organic salt drilling fluid system disclosed in the above patent is only for a density of about 1.30 g / cm 3 and a temperature resistance of 150°C, with relatively narrow applicable density and temperature ranges and no serialization. Although the organic salt drilling fluid system disclosed in the above paper has been serialized with a density range of 1.18 - 2.60 g / cm 3 , its temperature resistance is 120°C and 150°C, with a relatively narrow applicable temperature range and unable to meet the production requirements of most wells on site; moreover, the iron ore powder used is currently restricted due to environmental protection requirements, and its repeatability and application effects are in doubt. Summary of the Invention

[0006] The object of the present invention is to provide a high-efficiency organic salt water-based drilling fluid with a wide application range, high cost performance, and a database formed through multiple serializations for on-site engineers to use as a template, and a preparation method thereof. The density of the multi-serialized high-efficiency organic salt water-based drilling fluid is 1.20 - 2.44 g / cm 3 and its temperature resistance is 150°C - 200°C.

[0007] To solve the above technical problems, the technical solution provided by the present invention is as follows:

[0008] In the first aspect, the present invention provides a multi-serialized high-efficiency organic salt water-based drilling fluid, which comprises 100 parts of solvent water, 3 - 4 parts of viscosity increasing agent, 0.12 - 0.16 parts of anhydrous sodium carbonate, 2 - 5.5 parts of filtration loss reducer, 2 - 5 parts of plugging and anti-collapse agent, 1 - 3 parts of inhibition and lubricant, 5 - 90 parts of soluble weighting agent, and 5 - 346 parts of inert weighting agent by weight.

[0009] Further, the viscosity increasing agent is a mixture of montmorillonite group clay minerals and sepiolite group clay minerals;

[0010] Montmorillonite group clay minerals have a large cation exchange capacity, and water molecules can easily enter the interlayer of crystal layers. Therefore, they have strong mud-making ability, can form a dense and tough mud cake, and achieve the purpose of reducing the filtration loss. However, they are prone to high-temperature thickening in a high-temperature environment, which causes the performance of the drilling fluid to deteriorate sharply. Sepiolite group clay minerals mainly have a double-chain structure. The internal polycrystalline channels can adsorb more free water, have good thermal stability, and their appearance is fibrous. After the suspension prepared from it is stirred, the fibers cross each other to form a grid structure like a "heap of disordered straws", making the suspension stable. However, its disadvantage is that it is difficult to form a mud cake with good quality, so the filtration loss is relatively large. When the two clay minerals are compounded and used, it can not only weaken the high-temperature thickening effect of montmorillonite group clay minerals, but also reduce the disadvantage of poor filtration loss and wall-building property of sepiolite group clay minerals.

[0011] Further preferably, the weight ratio of montmorillonite group clay minerals to sepiolite group clay minerals is 1:(1 - 3).

[0012] The filtration loss reducer is at least one of modified cellulose ether filtration loss reducers with a substitution degree of 0.8 - 1.5 and polymer filtration loss reducers whose molecular structure contains an associable cyclic structure, a sulfonic acid group or a silicone group.

[0013] Modified cellulose ethers have good heat resistance stability and salt tolerance. In the drilling fluid system, they can adsorb multiple clay particles to form a spatial grid structure, effectively reducing the filtration loss of the drilling fluid system; when the substitution degree is 0.8 - 1.5, they are not easily biodegradable, which can avoid performance degradation and failure. Polymer filtration loss reducers whose molecular structure contains an associable cyclic structure, a sulfonic acid group or a silicone group can, by optimizing the synthesis process, control the polymer molecular size and the proportion of hydrated groups within a reasonable range. Therefore, they can effectively block the pores of the mud cake and form a good hydrated film on the surface of the mud cake, effectively reducing the filtration loss of the drilling fluid system; on the one hand, the cyclic structure increases the rigidity and temperature resistance of the polymer molecular chain, and on the other hand, it makes the polymer molecular structure contain both hydrophilic groups and hydrophobic groups. This not only weakens the adsorption between the polymer and the solid particles in the drilling fluid system, keeping the drilling fluid system at a relatively low viscosity, but also as the temperature rises, the methylene chain segments in the side chain of the cyclic structure produce hydrophobic association, resulting in an increase in the hydrodynamic system of the polymer molecule and an increase in viscosity, offsetting the viscosity decrease caused by the thermal degradation of the polymer and the hydration of the adsorbed groups, making the drilling fluid macroscopically show a stable rheological performance. The two types of polymers can be used alone or in combination to further enhance the filtration loss and wall-building performance.

[0014] The plugging and anti-collapse agent is at least one of sulfonated asphalt and sulfonated asphalt salt formed by water-soluble modification of asphalt with a softening point of 40°C - 150°C and a water-soluble content exceeding 40%.

[0015] The asphalt with a softening point of 40°C to 150°C matches the formation temperature of most well sections to be plugged. Unmodified asphalt is oil-soluble and cannot be effectively dispersed in water-based drilling fluids, nor can it effectively combine with other components in the drilling fluid system to play a good role in plugging and preventing cave-ins. After modification to make the water-soluble content exceed 40%, it can effectively combine with other components in the drilling fluid system to form a mud cake with good quality, playing an effective role in plugging and preventing cave-ins.

[0016] The inhibitory lubricant is at least one of polyhydric alcohols with a cloud point of 40 to 90°C.

[0017] Polyhydric alcohols form a hydrophobic film similar to oil on the surface of shale through the cloud point effect, preventing shale hydration and dispersion, playing a role in stabilizing the wellbore, and improving the lubricity of the drilling fluid. The cloud point is an important performance index of polyhydric alcohol-based inhibitory lubricants, which is related to the molecular structure, dosage, and salt content of polyhydric alcohols. By controlling raw materials and synthesis processes, the molecular structure of polyhydric alcohols is adjusted to prepare a series of polyhydric alcohols with a cloud point of 40°C to 90°C. And through the action of a small amount of salt, the adsorption form of polyhydric alcohols and clay is changed from multi-layer adsorption that is not conducive to wellbore stability to single-molecule adsorption that is conducive to wellbore stability, thereby further improving its inhibitory performance. During on-site application, polyhydric alcohols with a suitable cloud point are selected according to the formation temperature to maximize their inhibitory and lubricating effects.

[0018] The soluble weighting agent is at least one of low-carbon organic salts, soluble salts of halogen elements, and soluble salts of nitrogen group elements with a saturated solution density of 1.35 to 1.55 g / cm 3 3.

[0019] Soluble weighting agents can effectively reduce the solid content of drilling fluids, which is beneficial to controlling rheology and increasing the rate of penetration. Moreover, low-carbon organic salts can keep the system performance stable by consuming oxygen in the drilling fluid system under high-temperature environments. Especially after combining with ammonium ions, their inhibitory performance is improved, which is beneficial to overcoming the deterioration of drilling fluid system performance caused by clay hydration and dispersion.

[0020] The inert weighting agent is a mixture of fine calcium with a density of 2.7 to 2.9 g / cm 3 3 and a particle size of 1250 mesh and barite with a density of 4.2 g / cm 3 3 and a residue on a 200-mesh sieve of not more than 3.0%.

[0021] Fine calcium with a particle size of 1250 mesh and uniform can not only act as a weighting agent in the drilling fluid system, but also plug the pores in the mud cake, which is beneficial to forming a high-quality mud cake. Preferably, the weight ratio of fine calcium to barite is 1:(0 to 115).

[0022] In a second aspect, the salt content in the drilling fluid affects the extended state of the polymer molecular chains and their functional groups, thereby affecting the interaction between the polymer and other components in the drilling fluid and the size of the particles formed by the polymer. By reasonably controlling the amount and addition time of the salt, the salt content in the drilling fluid can be controlled. On the one hand, the extended state of the polymer molecular chains and functional groups can be maintained within a reasonable range, maximizing the interaction between the polymer and other components in the drilling fluid and keeping the drilling fluid in good performance. On the other hand, the particles formed by the polymer can be precisely within the range of colloidal particles, blocking the pores in the mud cake through deformation and effectively reducing the filtration loss.

[0023] For this reason, the present invention provides a preparation method for a multi-series of high-efficiency water-based drilling fluids with organic salts, which is as follows:

[0024] For the preparation method of a multi-series of high-efficiency water-based drilling fluids with a density of 1.20 - 1.80 g / cm 3 , the steps are as follows:

[0025] S1. Measure 100 parts by weight of solvent water, and under high-speed electric stirring, add a viscosifier and anhydrous sodium carbonate accounting for 4 wt.% of the amount of the viscosifier, and stir for 20 min;

[0026] S2. After step S1 is completed, under high-speed electric stirring, slowly add a filtration reducer and stir for 30 min;

[0027] S3. After step S2 is completed, under high-speed electric stirring, slowly add a plugging and anti-collapse agent and an inhibition lubricant, and stir for 20 min;

[0028] S4. After step S3 is completed, under high-speed electric stirring, add a soluble weighting material and stir for 30 min;

[0029] S5. After step S4 is completed, under high-speed electric stirring, add an inert weighting material and stir for 40 min to obtain a series of high-efficiency water-based drilling fluids for drilling engineering with a density of 1.20 - 1.80 g / cm 3 .

[0030] Preferably, in steps S1 - S5, the speed of high-speed electric stirring is 11000 ± 300 r / min.

[0031] For the preparation method of a multi-series of high-efficiency water-based drilling fluids with a density of 1.81 - 2.44 g / cm 3 , the steps are as follows:

[0032] S1. Measure 100 parts by weight of solvent water, and under high-speed electric stirring, add a viscosifier and anhydrous sodium carbonate accounting for 4 wt.% of the amount of the viscosifier, and stir for 20 min;

[0033] S2. After step S1 is completed, while under high-speed electric stirring, add soluble weighting materials accounting for 50% of the occupancy, and stir for 20 min;

[0034] S3. After step S2 is completed, while under high-speed electric stirring, slowly add a filtration reducer, and stir for 30 min;

[0035] S4. After step S3 is completed, while under high-speed electric stirring, slowly add a plugging and anti-collapse agent and an inhibition lubricant, and stir for 20 min;

[0036] S5. After step S4 is completed, while under high-speed electric stirring, add soluble weighting materials accounting for 50% of the occupancy, and stir for 30 min;

[0037] S6. After step S5 is completed, while under high-speed electric stirring, add inert weighting materials, and stir for 40 min to obtain a series of high-efficiency water-based drilling fluids for drilling engineering with a density of 1.81 - 2.44 g / cm 3 ³.

[0038] Preferably, in steps S1 - S6, the speed of high-speed electric stirring is 11000 ± 300 r / min.

[0039] Integrating the above technical solutions, the technical effects that the present invention can achieve are as follows:

[0040] The density of the multi-series organic salt high-efficiency water-based drilling fluid prepared by the above method is 1.20 - 2.44 g / cm 3 ³, and the temperature resistance is 150°C - 200°C.

[0041] Compared with the prior art, the multi-series organic salt high-efficiency water-based drilling fluid provided by the present invention has the following advantages: ① It forms a multi-series organic salt drilling fluid with a density of 1.20 - 2.44 g / cm 3 ³ and a temperature resistance of 150°C - 200°C. The system has stable performance and a wide application range, filling the current technical gap. ② The system forms a database through multi-series for on-site engineers to use as a template, reducing the uncertainty of application effects and well control risks, and achieving the unity of economic and social benefits. Specific Embodiments

[0042] In order to make the purpose, technical solutions and advantages of the present invention clearer, the following further elaborates on the present invention in combination with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0043] Accordingly, the following detailed description of the provided embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0044] Unless otherwise specified, the experimental methods used in the following embodiments are all conventional methods; the reagents, materials, etc. used in the following embodiments, unless otherwise specified, can all be obtained from commercial sources, and are strictly tested in accordance with industry standards or enterprise standards during the experiment, and can only be used after passing the test.

[0045] Specifically, see Table 1:

[0046] Table 1:

[0047] Example 1

[0048] Density 1.20 g / cm 3 , high-efficiency organic salt water-based drilling fluid I with a temperature resistance of 150 °C, and its preparation method is as follows:

[0049] S1. Measure 100 parts by weight of solvent water, and add 4 parts of BZ-TQJ and 0.16 part of anhydrous sodium carbonate under high-speed electric stirring, and stir for 20 min;

[0050] S2. After step S1 is completed, slowly add 2 parts of BZ-KLS-II under high-speed electric stirring, and stir for 30 min;

[0051] S3. After step S2 is completed, slowly add 5 parts of BZ-YFT and 3 parts of BZ-YRH-I under high-speed electric stirring, and stir for 20 min;

[0052] S4. After step S3 is completed, add 5 parts of Weigh2 under high-speed electric stirring, and stir for 30 min;

[0053] S5. After step S4 is completed, add 3 parts of fine calcium and 27 parts of barite under high-speed electric stirring, and stir for 40 min to obtain a high-efficiency organic salt water-based drilling fluid with a density of 1.20 g / cm 3 and a temperature resistance of 150 °C.

[0054] Example 2

[0055] Density 1.60 g / cm 3 , high-efficiency organic salt water-based drilling fluid II with a temperature resistance of 150 °C, and its preparation method is as follows:

[0056] S1. Measure 100 parts by weight of solvent water. Under high-speed electric stirring, add 3 parts of BZ-TQJ and 0.12 part of anhydrous sodium carbonate, and stir for 20 min;

[0057] S2. After step S1 is completed, under high-speed electric stirring, slowly add 2 parts of BZ-KLS-II, and stir for 30 min;

[0058] S3. After step S2 is completed, under high-speed electric stirring, slowly add 3 parts of NFA-25 and 3 parts of BZ-YRH-I, and stir for 20 min;

[0059] S4. After step S3 is completed, under high-speed electric stirring, add 20 parts of Weigh2, and stir for 30 min;

[0060] S5. After step S4 is completed, under high-speed electric stirring, add 3 parts of fine calcium and 77.5 parts of barite, and stir for 40 min to obtain an organic salt high-efficiency water-based drilling fluid with a density of 1.60 g / cm 3 , with a temperature resistance of 150 °C.

[0061] Example 3

[0062] Density 1.84 g / cm 3 , organic salt high-efficiency water-based drilling fluid III with a temperature resistance of 150 °C, and its preparation method is as follows:

[0063] S1. Measure 100 parts by weight of solvent water. Under high-speed electric stirring, add 3 parts of BZ-TQJ and 0.12 part of anhydrous sodium carbonate, and stir for 20 min;

[0064] S2. After step S1 is completed, under high-speed electric stirring, add 25 parts of Weigh2, and stir for 20 min;

[0065] S3. After step S2 is completed, under high-speed electric stirring, slowly add 2 parts of BZ-KLS-II, and stir for 30 min;

[0066] S4. After step S3 is completed, under high-speed electric stirring, slowly add 3 parts of BZ-YFT and 3 parts of BZ-YRH-I, and stir for 20 min;

[0067] S5. After step S4 is completed, under high-speed electric stirring, add 25 parts of Weigh2, and stir for 30 min;

[0068] S6. After step S5 is completed, under high-speed electric stirring, add 3 parts of fine calcium and 131 parts of barite, and stir for 40 min to obtain an organic salt high-efficiency water-based drilling fluid with a density of 1.84 g / cm 3 , with a temperature resistance of 150 °C.

[0069] Example 4

[0070] Density 2.02 g / cm 3 , high-efficiency organic salt water-based drilling fluid Ⅳ with a temperature resistance of 150°C, and its preparation method is as follows:

[0071] S1. Measure 100 parts by weight of solvent water, and under high-speed electric stirring, add 3 parts of BZ-TQJ and 0.12 part of anhydrous sodium carbonate, and stir for 20 min;

[0072] S2. After step S1 is completed, under high-speed electric stirring, add 25 parts of BZ-YJZ-Ⅱ, and stir for 20 min;

[0073] S3. After step S2 is completed, under high-speed electric stirring, add 3 parts of BZ-KLS-Ⅱ, and stir for 30 min;

[0074] S4. After step S3 is completed, under high-speed electric stirring, slowly add 3 parts of BZ-YFT and 3 parts of BZ-YRH-Ⅰ, and stir for 20 min;

[0075] S5. After step S4 is completed, under high-speed electric stirring, add 25 parts of BZ-YJZ-Ⅱ, and stir for 30 min;

[0076] S6. After step S5 is completed, under high-speed electric stirring, add 3 parts of fine calcium and 174 parts of barite, and stir for 40 min to obtain the high-efficiency organic salt water-based drilling fluid with a density of 2.02 g / cm 3 , and a temperature resistance of 150°C.

[0077] Example 5

[0078] Density 2.25 g / cm 3 , high-efficiency organic salt water-based drilling fluid Ⅴ with a temperature resistance of 150°C, and its preparation method is as follows:

[0079] S1. Measure 100 parts by weight of solvent water, and under high-speed electric stirring, add 3 parts of BZ-TQJ and 0.12 part of anhydrous sodium carbonate, and stir for 20 min;

[0080] S2. After step S1 is completed, under high-speed electric stirring, add 15 parts of BZ-YJZ-Ⅰ and 30 parts of BZ-YJZ-Ⅱ, and stir for 20 min;

[0081] S3. After step S2 is completed, under high-speed electric stirring, slowly add 1 part of BZ-KLS-Ⅰ and 2 parts of BZ-KLS-Ⅱ, and stir for 30 min;

[0082] S4. After step S3 is completed, under high-speed electric stirring, slowly add 3 parts of BZ-YFT and 3 parts of BZ-YRH-Ⅰ, and stir for 20 min;

[0083] S5. After step S4 is completed, while under high-speed electric stirring, add 15 parts of BZ-YJZ-I and 30 parts of BZ-YJZ-II, and stir for 30 min;

[0084] S6. After step S5 is completed, while under high-speed electric stirring, add 3 parts of fine calcium and 250 parts of barite, and stir for 40 min, thus obtaining an organic salt-based high-efficiency water-based drilling fluid with a density of 2.25 g / cm 3 and a temperature resistance of 150 °C.

[0085] Example 6

[0086] An organic salt-based high-efficiency water-based drilling fluid VI with a density of 2.44 g / cm 3 and a temperature resistance of 150 °C, and its preparation method is as follows:

[0087] S1. Measure 100 parts by weight of solvent water. While under high-speed electric stirring, add 3 parts of BZ-TQJ and 0.12 part of anhydrous sodium carbonate, and stir for 20 min;

[0088] S2. After step S1 is completed, while under high-speed electric stirring, add 15 parts of BZ-YJZ-I and 30 parts of Weigh3, and stir for 20 min;

[0089] S3. After step S2 is completed, while under high-speed electric stirring, slowly add 1 part of BZ-KLS-I and 2 parts of BZ-KLS-II, and stir for 30 min;

[0090] S4. After step S3 is completed, while under high-speed electric stirring, slowly add 4 parts of NFA-25 and 3 parts of BZ-YRH-I, and stir for 20 min;

[0091] S5. After step S4 is completed, while under high-speed electric stirring, add 15 parts of BZ-YJZ-I and 30 parts of Weigh3, and stir for 30 min;

[0092] S6. After step S5 is completed, while under high-speed electric stirring, add 3 parts of fine calcium and 343 parts of barite, and stir for 40 min, thus obtaining an organic salt-based high-efficiency water-based drilling fluid with a density of 2.44 g / cm 3 and a temperature resistance of 150 °C.

[0093] Example 7

[0094] An organic salt-based high-efficiency water-based drilling fluid product VII with a density of 1.27 g / cm 3 and a temperature resistance of 180 °C, and its preparation method is as follows:

[0095] S1. Measure 100 parts by weight of solvent water. While under high-speed electric stirring, add 3 parts of BZ-TQJ and 0.12 part of anhydrous sodium carbonate, and stir for 20 min;

[0096] S2. After step S1 is completed, while under high-speed electric stirring, slowly add 1 part of BZ-KLS-I and 3 parts of BZ-KLS-III, and stir for 30 min;

[0097] S3. After step S2 is completed, while under high-speed electric stirring, slowly add 3 parts of NFA-25 and 2 parts of BZ-YRH-II, and stir for 20 min;

[0098] S4. After step S3 is completed, while under high-speed electric stirring, add 50 parts of Weigh2, and stir for 30 min;

[0099] S5. After step S4 is completed, while under high-speed electric stirring, add 5 parts of fine calcium, and stir for 40 min, thus obtaining an organic salt high-efficiency water-based drilling fluid with a density of 1.27 g / cm 3 , which can resist a temperature of 180 °C.

[0100] Example 8

[0101] with a density of 1.80 g / cm 3 , an organic salt high-efficiency water-based drilling fluid VIII that can resist a temperature of 180 °C, and its preparation method is as follows:

[0102] S1. Measure 100 parts by weight of solvent water. While under high-speed electric stirring, add 3 parts of BZ-TQJ and 0.12 part of anhydrous sodium carbonate, and stir for 20 min;

[0103] S2. After step S1 is completed, while under high-speed electric stirring, add 25 parts of Weigh2, and stir for 20 min;

[0104] S3. After step S2 is completed, while under high-speed electric stirring, slowly add 0.5 part of BZ-KLS-I and 2 parts of BZ-KLS-III, and stir for 30 min;

[0105] S4. After step S3 is completed, while under high-speed electric stirring, slowly add 3 parts of BZ-YFT and 2 parts of BZ-YRH-II, and stir for 20 min;

[0106] S5. After step S4 is completed, while under high-speed electric stirring, add 25 parts of Weigh2, and stir for 30 min;

[0107] S6. After step S5 is completed, while under high-speed electric stirring, add 3 parts of fine calcium and 130 parts of barite, and stir for 40 min, thus obtaining an organic salt high-efficiency water-based drilling fluid with a density of 1.80 g / cm 3 , which can resist a temperature of 180 °C.

[0108] Example 9

[0109] with a density of 2.23 g / cm 3, the high-efficiency organic salt water-based drilling fluid Ⅸ with a temperature resistance of 180°C, and its preparation method is as follows:

[0110] S1. Measure 100 parts by weight of solvent water, and under high-speed electric stirring, add 3 parts of BZ-TQJ and 0.12 part of anhydrous sodium carbonate, and stir for 20 min;

[0111] S2. After step S1 is completed, under high-speed electric stirring, add 15 parts of BZ-YJZ-I and 30 parts of Weigh3, and stir for 20 min;

[0112] S3. After step S2 is completed, under high-speed electric stirring, slowly add 0.5 part of BZ-KLS-I, 2 parts of BZ-KLS-II, and 3 parts of BZ-KLS-III, and stir for 30 min;

[0113] S4. After step S3 is completed, under high-speed electric stirring, slowly add 2 parts of BZ-YFT and 1 part of BZ-YRH-II, and stir for 20 min;

[0114] S5. After step S4 is completed, under high-speed electric stirring, add 15 parts of BZ-YJZ-I and 30 parts of Weigh3, and stir for 30 min;

[0115] S6. After step S5 is completed, under high-speed electric stirring, add 5 parts of fine calcium and 243 parts of barite, and stir for 40 min to obtain the organic salt high-efficiency water-based drilling fluid with a density of 2.23 g / cm 3 and a temperature resistance of 180°C.

[0116] Example 10

[0117] Density 1.60 g / cm 3 , the high-efficiency organic salt water-based drilling fluid Ⅹ with a temperature resistance of 200°C, and its preparation method is as follows:

[0118] S1. Measure 100 parts by weight of solvent water, and under high-speed electric stirring, add 3 parts of BZ-TQJ and 0.12 part of anhydrous sodium carbonate, and stir for 20 min;

[0119] S2. After step S1 is completed, under high-speed electric stirring, slowly add 0.5 part of BZ-KLS-I and 2 parts of BZ-KLS-III, and stir for 30 min;

[0120] S3. After step S2 is completed, under high-speed electric stirring, slowly add 3 parts of BZ-YFT and 2 parts of BZ-YRH-III, and stir for 20 min;

[0121] S4. After step S3 is completed, under high-speed electric stirring, add 30 parts of Weigh2, and stir for 30 min;

[0122] S5. After step S4 is completed, under high-speed electric stirring, add 3 parts of fine calcium and 55 parts of barite, and stir for 40 min to obtain an organic salt high-efficiency water-based drilling fluid with a density of 1.60 g / cm 3 , with a temperature resistance of 200 °C.

[0123] Example 11

[0124] Density 2.00 g / cm 3 , organic salt high-efficiency water-based drilling fluid XI with a temperature resistance of 200 °C, and its preparation method is as follows:

[0125] S1. Measure 100 parts by weight of solvent water. Under high-speed electric stirring, add 3 parts of BZ-TQJ and 0.12 part of anhydrous sodium carbonate, and stir for 20 min;

[0126] S2. After step S1 is completed, under high-speed electric stirring, add 25 parts of BZ-YJZ-I, and stir for 20 min;

[0127] S3. After step S2 is completed, under high-speed electric stirring, slowly add 0.5 part of BZ-KLS-I and 2 parts of BZ-KLS-III, and stir for 30 min;

[0128] S4. After step S3 is completed, under high-speed electric stirring, slowly add 4 parts of BZ-YFT and 3 parts of BZ-YRH-3-III, and stir for 20 min;

[0129] S5. After step S4 is completed, under high-speed electric stirring, add 25 parts of BZ-YJZ-I, and stir for 30 min;

[0130] S6. After step S5 is completed, under high-speed electric stirring, add 5 parts of fine calcium and 193 parts of barite, and stir for 40 min to obtain an organic salt high-efficiency water-based drilling fluid with a density of 2.00 g / cm 3 , with a temperature resistance of 200 °C.

[0131] Example 12

[0132] Density 2.22 g / cm 3 , organic salt high-efficiency water-based drilling fluid XII with a temperature resistance of 200 °C, and its preparation method is as follows:

[0133] S1. Measure 100 parts by weight of solvent water. Under high-speed electric stirring, add 3 parts of BZ-TQJ and 0.12 part of anhydrous sodium carbonate, and stir for 20 min;

[0134] S2. After step S1 is completed, under high-speed electric stirring, add 15 parts of Weigh2 and 30 parts of BZ-YJZ-II, and stir for 20 min;

[0135] S3. After step S2 is completed, 0.5 part of BZ-KLS-I and 3 parts of BZ-KLS-III are slowly added under high-speed electric stirring, and stirred for 30 min;

[0136] S4. After step S3 is completed, 4 parts of BA-YFT and 1 part of BZ-YRH-III are slowly added under high-speed electric stirring, and stirred for 20 min;

[0137] S5. After step S4 is completed, 15 parts of Weigh2 and 30 parts of BZ-YJZ-II are added under high-speed electric stirring, and stirred for 30 min;

[0138] S6. After step S5 is completed, 5 parts of fine calcium and 244 parts of barite are added under high-speed electric stirring, and stirred for 40 min, thus obtaining an organic salt high-efficiency water-based drilling fluid with a density of 2.22 g / cm 3 , and a high temperature resistance of 200 °C.

[0139] Performance test:

[0140] Referring to "GB / T16783.1-2014 Petroleum and natural gas industries - Drilling fluids - Field testing - Part 1: Water-based drilling fluids", various performances of the drilling fluid products I - XII prepared in Examples 1 - 12 before and after aging are tested. Test temperature: 50 °C; Aging conditions: 150 °C / 16 h, 180 °C / 16 h, 200 °C / 16 h.

[0141] The test results are shown in Table 2 below.

[0142] Table 2:

[0143] From the test results in the above table, it can be seen that for the drilling fluid products I - XII prepared in Examples 1 - 12, the rheological properties of the system are stable before and after high-temperature aging, the dynamic shear force is moderate, the low-temperature and low-pressure filtration loss and the high-temperature and high-pressure filtration loss are respectively within 2.5 mL and 15.0 mL, meeting the requirements of on-site application; for the high-density drilling fluid with a density exceeding 2.20 g / cm 3 , the sedimentation stability of the system is good, and there is no sedimentation phenomenon of the weighting material, meeting the on-site construction requirements of high-density wells.

[0144] Furthermore, according to the addition amounts in Examples 3, 4, and 9 and a density of 1.20 - 1.80 g / cm 3 , drilling fluids are prepared by the preparation method of the drilling fluid, as Comparative Example 1, Comparative Example 2, and Comparative Example 3.

[0145] Test the properties of the above six groups of drilling fluids before and after aging to evaluate the influence of the preparation method on the properties of the drilling fluid. Test temperature: 50 °C; aging conditions: 180 °C / 16 h, 150 °C / 16 h.

[0146] The test results are shown in Table 3 below.

[0147] Table 3:

[0148] From the test results in the above table, it can be seen that the viscosities of the drilling fluid products III, IV, and IX prepared in Examples 3, 4, and 9 are moderate. After aging, the retention rate exceeds 95%, and both the low-temperature and low-pressure filtration loss and the high-temperature and high-pressure filtration loss are maintained at a relatively reasonable level, meeting the requirements of on-site applications. However, the viscosities of the drilling fluid products prepared in Comparative Examples 1, 2, and 3 are on the high side, and they decrease significantly after aging, and the high-temperature and high-pressure filtration loss is on the high side. The comparison of the two groups of formulations proves the influence of the preparation method on the properties of the drilling fluid. By changing the addition sequence and amount of the soluble weighting agent, the preparation method of the drilling fluid is determined, and on the premise that the dosage of the drilling fluid treatment agent remains unchanged, the properties of the drilling fluid are optimized.

[0149] Furthermore, use thickening agent 1 (montmorillonite), thickening agent 2 (sepiolite), inert weighting agent 1 (barite), and inert weighting agent 2 (fine calcium: barite = 12:127) to replace the thickening agent and inert weighting agent in Example 3 respectively, as Comparative Example 4, Comparative Example 5, Comparative Example 6, and Comparative Example 7.

[0150] Test the properties of the above four groups of drilling fluids before and after aging to evaluate the influence of the thickening agent and inert weighting agent on the properties of the drilling fluid. Test temperature: 50 °C, aging conditions: 150 °C / 16 h.

[0151] The test results are shown in Table 4 below.

[0152] Table 4:

[0153] From the test results in the above table, it can be seen that the thickening agent and inert weighting agent have a great influence on the rheological and filtration and wall-building properties of the drilling fluid. In the present invention, the research personnel determined through experiments that when the weight ratio of montmorillonite group clay minerals to sepiolite group clay minerals in the thickening agent is 1:(1 - 3), and the weight ratio of fine calcium with a density of 2.70 - 2.90 g / cm 3 and a particle size of 1250 mesh to barite with a density of 4.20 g / cm 3 and a 200-mesh sieve residue not greater than 3.0% is 1:(0 - 115), the properties of the drilling fluid are optimal.

[0154] Furthermore, according to the preparation schemes similar to those of Examples 1, 2, and 8, prepare the following three groups of comparative examples:

[0155] Comparative Example 8: 100 parts by weight of water, 4 parts by weight of a commercially available similar viscosifier, 0.16 part by weight of anhydrous sodium carbonate, 0.1 part by weight of a commercially available coating agent, 1 part by weight of a commercially available similar fluid loss reducer 1, 3 parts by weight of a commercially available similar fluid loss reducer 2, 5 parts by weight of a commercially available similar plugging and anti-collapse agent, 3 parts by weight of a commercially available similar inhibitor lubricant, 20 parts by weight of a commercially available similar organic salt 1, 3 parts by weight of fine calcium, 14 parts by weight of barite.

[0156] Comparative Example 9: 100 parts by weight of water, 3 parts by weight of a commercially available similar viscosifier, 0.12 part by weight of anhydrous sodium carbonate, 1.5 parts by weight of a commercially available similar fluid loss reducer 1, 2 parts by weight of a commercially available similar fluid loss reducer 2, 3 parts by weight of a commercially available similar plugging and anti-collapse agent, 3 parts by weight of a commercially available similar inhibitor lubricant, 20 parts by weight of a commercially available similar organic salt 1, 3 parts by weight of fine calcium, 77.5 parts by weight of barite.

[0157] Comparative Example 10: 100 parts by weight of water, 3 parts by weight of a commercially available similar viscosifier, 0.12 part by weight of anhydrous sodium carbonate, 0.5 part by weight of a commercially available similar fluid loss reducer 1, 4 parts by weight of a commercially available similar fluid loss reducer 3, 3 parts by weight of a commercially available similar plugging and anti-collapse agent, 2 parts by weight of a commercially available similar inhibitor lubricant, 50 parts by weight of a commercially available similar organic salt 1, 3 parts by weight of fine calcium, 130 parts by weight of barite.

[0158] Test the properties of the above three groups of drilling fluids before and after aging to evaluate the influence of commercially available similar treatment agents on the properties of the drilling fluids. The test temperature is 50°C; aging conditions: 150°C / 16 h, 180°C / 16 h.

[0159] The test results are shown in Table 5 below.

[0160] Table 5:

[0161] It can be seen from the test results in the above table that for the drilling fluids prepared in Comparative Examples 8 to 10, after high-temperature aging, the decline rate of the apparent viscosity of the system exceeds 30%, and phenomena such as agglomeration, uneven density, and precipitation occur, which are not conducive to on-site application. Compared with Examples 1, 2, and 8, the advantages of the examples are highlighted.

[0162] Furthermore, according to the addition amounts and preparation methods of Examples 3 and 4, the following two groups of comparative examples are prepared.

[0163] Comparative Example 11: 100 parts by weight of water, 3 parts by weight of a commercially available similar viscosifier, 0.12 part by weight of anhydrous sodium carbonate, 1.5 parts by weight of a commercially available similar fluid loss reducer 1, 2 parts by weight of a commercially available similar fluid loss reducer 2, 3 parts by weight of a commercially available similar plugging and anti-collapse agent, 3 parts by weight of a commercially available similar inhibitor lubricant, 50 parts by weight of a commercially available similar organic salt 1, 3 parts by weight of fine calcium, 131 parts by weight of barite.

[0164] Comparative Example 12: 100 parts by weight of water, 3 parts by weight of a commercially available similar thixotropic agent, 0.12 part by weight of anhydrous sodium carbonate, 1.5 parts by weight of a commercially available similar fluid loss reducer 1, 2 parts by weight of a commercially available similar fluid loss reducer 2, 3 parts by weight of a commercially available similar plugging and anti-collapse agent, 3 parts by weight of a commercially available similar inhibition lubricant, 50 parts by weight of a commercially available similar organic salt 1, 30 parts by weight of a commercially available similar organic salt 2, 3 parts by weight of fine calcium, 174 parts by weight of barite.

[0165] Test the properties of the above four groups of drilling fluids before and after long-term aging to evaluate the high-temperature effectiveness of the drilling fluids. The test temperature is 50 °C; aging conditions: 150 °C / 16 h, 150 °C / 48 h, 150 °C / 72 h.

[0166] The test results are shown in Table 6 below.

[0167] Table 6:

[0168] From the test results in the above table, it can be seen that after aging at 150 °C / 16 h and 150 °C / 48 h, the drilling fluid products III and IV prepared in Examples 3 and 4 have stable rheological properties, moderate yield point, and relatively reasonable high-temperature and high-pressure fluid loss, meeting the requirements of on-site applications. After aging the drilling fluids prepared in Comparative Examples 11 and 12 at 150 °C / 48 h, both the rheology and the high-temperature and high-pressure fluid loss change greatly; during on-site application, to maintain the stability of the drilling fluid performance and ensure safe drilling, it is necessary to continuously add treatment agents. Under the same conditions, the drilling fluids prepared in the examples have a longer stable performance time and a lower adjustment and maintenance frequency than those prepared in the comparative examples, which virtually reduces the production cost and increases the profit margin.

[0169] In summary, the multi-series organic salt high-efficiency water-based drilling fluid of the present application has an applicable density of 1.20 - 2.44 g / cm 3 and an applicable temperature of 150 °C - 200 °C; its preparation method is simple, the performance is stable before and after high-temperature aging, the yield point is moderate, and the low-temperature and low-pressure as well as high-temperature and high-pressure fluid loss are all in a relatively reasonable range, meeting the requirements of on-site applications. Compared with the currently used drilling fluids in the market, on the one hand, this system covers a wide range of densities and temperatures, meeting the use requirements of most wells on site, and through multi-series formation of a database, it can be provided to on-site engineers in the form of a template for flexible selection according to production needs, saving production time and reducing well control risks; on the other hand, the system has a long stable performance time and a low adjustment and maintenance frequency, which is conducive to reducing production costs and increasing the profit margin. This technology fills the current gap and realizes the unity of economic and social benefits.

[0170] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multi - serialized organic salt high - efficiency water - based drilling fluid, characterized in that, it comprises 100 parts of solvent water by weight, 3 - 4 parts of viscosifier, 0.12 - 0.16 parts of anhydrous sodium carbonate, 2 - 5.5 parts of filtrate reducer, 2 - 5 parts of plugging and anti - collapse agent, 1 - 3 parts of inhibitor and lubricant, 5 - 90 parts of soluble weighting agent and 5 - 346 parts of inert weighting agent; Among them, the cuttings-carrying agent is a mixture of montmorillonite group clay minerals and sepiolite group clay minerals, and the weight ratio of the two is 1:(1-3); the filtration loss reducer is at least one of modified cellulose ether filtration loss reducers with a substitution degree of 0.8-1.5 and polymer filtration loss reducers containing an associable cyclic structure, a sulfonic acid group or an organosilicon group in the molecular structure; the plugging and anti-collapse agent is at least one of sulfonated asphalt and sulfonated asphalt salt with a water-soluble content of more than 40% formed by water-soluble modification of asphalt with a softening point of 40°C to 150°C; the inhibition lubricant is at least one of polyhydric alcohols with a cloud point of 40-90°C; the soluble weighting agent saturated solution density is 1.35-1.55 g / cm 3 of at least one of low-carbon organic salts, soluble salts of halogen elements, and soluble salts of nitrogen group elements; the inert weighting agent is a density of 2.7-2.9 g / cm 3 , fine calcium with a particle size of 1250 mesh and a density of 4.2 g / cm 3 , a mixture of barite with a 200-mesh screen residue of not more than 3.0%, and the weight ratio of the two is 1:(0-115).

2. The multi - serialized organic salt high - efficiency water - based drilling fluid according to claim 1, characterized in that, The density of the multi-series organic salt-based high-efficiency water-based drilling fluid is 1.20 g / cm 3 ~2.44 g / cm 3 .

3. The multi - serialized organic salt high - efficiency water - based drilling fluid according to claim 1, characterized in that, the applicable temperature of the multi - serialized organic salt high - efficiency water - based drilling fluid is 150°C - 200°C.

4. A preparation method of the multi - serialized organic salt high - efficiency water - based drilling fluid according to any one of claims 1 - 3, characterized in that, A preparation method of a multi-series organic salt high-efficiency water-based drilling fluid with a density of 1.20 to 1.80 g / cm 3 is as follows: S1. Measure 100 parts of solvent water by weight. Under high - speed electric stirring, add the viscosifier and 4 wt.% of anhydrous sodium carbonate based on the amount of the viscosifier, and stir for 20 min; S2. After step S1 is completed, under high - speed electric stirring, slowly add the filtrate reducer and stir for 30 min; S3. After step S2 is completed, under high - speed electric stirring, slowly add the plugging and anti - collapse agent and the inhibitor and lubricant, and stir for 20 min; S4. After step S3 is completed, under high - speed electric stirring, add the soluble weighting material and stir for 30 min; S5. After step S4 is completed, under high-speed electric stirring, add inert weighting materials and stir for 40 min to obtain a series of high-efficiency water-based drilling fluids for drilling engineering with a density of 1.20 - 1.80 g / cm 3 3 5. The multi - serialized organic salt high - efficiency water - based drilling fluid according to claim 4, characterized in that, in steps S1 - S5, the speed of high - speed electric stirring is 11000 ± 300 r / min.

6. A preparation method of the multi - serialized organic salt high - efficiency water - based drilling fluid according to any one of claims 1 - 3, characterized in that, A preparation method of a multi-series organic salt-based high-efficiency water-based drilling fluid with a density of 1.81 to 2.44 g / cm 3 is as follows: S1. Measure 100 parts of solvent water by weight. Under high - speed electric stirring, add the viscosifier and 4 wt.% of anhydrous sodium carbonate based on the amount of the viscosifier, and stir for 20 min; S2. After step S1 is completed, under high - speed electric stirring, add 50% of the soluble weighting material based on the occupied amount and stir for 20 min; S3. After step S2 is completed, under high - speed electric stirring, slowly add the filtrate reducer and stir for 30 min; S4. After step S3 is completed, under high - speed electric stirring, slowly add the plugging and anti - collapse agent and the inhibitor and lubricant, and stir for 20 min; S5. After step S4 is completed, under high - speed electric stirring, add 50% of the soluble weighting material based on the occupied amount and stir for 30 min; S6. After step S5 is completed, under high-speed electric stirring, an inert weighting material is added and stirred for 40 min to obtain a series of high-efficiency water-based drilling fluids for drilling engineering with a density of 1.81 - 2.44 g / cm 3 .

7. The multi - serialized organic salt high - efficiency water - based drilling fluid according to claim 6, characterized in that, in steps S1 - S6, the speed of high - speed electric stirring is 11000 ± 300 r / min.

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