Strong blocking biomass synthetic base drilling fluid and preparation method thereof

Abstract

The invention provides a strong plugging biomass synthetic base drilling fluid, which comprises: 65-100 parts by weight of a biomass synthetic base fluid; 0-35 parts by weight of an aqueous phase solution; 3-5 parts by weight of organic soil; 4-6 parts by weight of an emulsifier; 3-5 parts by weight of a filtrate reducer; 3-5 parts by weight of a rigid blocking agent; 2-4 parts by weight of modified lignin; 0.5 to 1.5 parts by weight of graphite oxide; and 2-3 parts of calcium oxide. Compared with the prior art, the strong-plugging biomass synthetic base drilling fluid provided by the invention adopts components with specific contents, the components have better interaction, and meanwhile, the plugging property is enhanced by utilizing scientific and reasonable combination of rigid materials, soft materials and sheet materials, so that the system has excellent lubricating, inhibiting and plugging properties and the like; and meanwhile, the drilling fluid has the advantages of greenness, biodegradability and environmental protection, and can meet the drilling construction requirements of shale oil / gas horizontal wells in southwest, China province and the like and environment-sensitive areas.

Description

Technical Field

[0001] The invention belongs to the technical field of drilling engineering, and in particular relates to a strong plugging biomass synthetic-based drilling fluid and a preparation method thereof. Background Art

[0002] With the increasing number of shale oil and gas horizontal wells and high-angle directional wells, synthetic-based drilling fluids are widely used due to their excellent lubrication and inhibition properties. At the same time, with the increasingly stringent national environmental protection requirements, the development of environmentally friendly synthetic-based drilling fluids has become the main direction of drilling fluid research and application.

[0003] In addition, from the perspective of reducing the risk of leakage and preventing the risk of groundwater environmental pollution, strengthening the plugging performance of drilling fluid is also a key consideration. Therefore, developing a drilling fluid system that has strong lubrication, inhibition, and plugging properties, and is green, environmentally friendly, and biodegradable has become a technical problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0004] In view of this, the technical problem to be solved by the present invention is to provide a strong plugging biomass synthetic-based drilling fluid and a preparation method thereof which has good lubrication, inhibition and plugging performance and is green, environmentally friendly and biodegradable.

[0005] The present invention provides a strong plugging biomass synthetic-based drilling fluid, comprising:

[0006]

[0007] The biomass synthesis base liquid includes one or more of dodecyl methyl ether, dodecyl ethyl ether and dodecyl butyl ether;

[0008] The modified lignin contains long-chain alkyl groups and amino groups.

[0009] Preferably, the aqueous phase solution contains an aqueous phase inhibitor; the aqueous phase inhibitor is selected from calcium chloride and / or potassium sulfate; and the mass concentration of the aqueous phase inhibitor in the aqueous phase solution is 20% to 40%.

[0010] Preferably, the organic soil is selected from alkyl quaternary ammonium salt modified bentonite;

[0011] The emulsifier has a structure shown in formula (I) or is prepared from polyene polyamine, cyclic acid anhydride, polyformaldehyde and cardanol:

[0012]

[0013] In formula (I), R1 is a C5-C12 alkyl group; R2 is a C10-C18 alkyl group; n is an integer of 1 to 4;

[0014] The fluid loss reducer is selected from humic acid amide;

[0015] The rigid plugging agent is selected from ultrafine calcium carbonate and nano calcium carbonate; the mass ratio of the ultrafine calcium carbonate to the nano calcium carbonate is (3-9):1.

[0016] Preferably, the carbon number of the alkyl group in the alkyl quaternary ammonium salt modified bentonite is 12-30.

[0017] Preferably, R1 is a C8 alkyl group; the polyene polyamine is selected from triethylenetetramine and / or tetraethylenepentamine; the cyclic acid anhydride is selected from maleic anhydride and / or succinic anhydride; and the molar ratio of the polyene polyamine, cyclic acid anhydride, polyformaldehyde and cardanol is 1:(2-2.1):2:(2.2-2.3):(4-5).

[0018] Preferably, the ultrafine calcium carbonate includes 500-800 mesh ultrafine calcium carbonate, 1000-1500 mesh ultrafine calcium carbonate and 2000-3000 mesh ultrafine calcium carbonate; the mass ratio of the 500-800 mesh ultrafine calcium carbonate, 1000-1500 mesh ultrafine calcium carbonate and 2000-3000 mesh ultrafine calcium carbonate is (0.5-2):(0.5-2):1.

[0019] Preferably, the invention further comprises 0.1 to 412 parts by weight of barite.

[0020] Preferably, the strong plugging biomass synthetic drilling fluid has a temperature of 90°C to 180°C and a density of 0.87 to 2.3 g / cm 3 The apparent viscosity within the range is less than 66 mPa·s, the medium-pressure filtration loss is less than 1 mL, and the high-temperature and high-pressure filtration loss is less than 2.8 mL.

[0021] The present invention also provides a method for preparing the above-mentioned strong plugging biomass synthetic-based drilling fluid, comprising the following steps:

[0022] S) mixing the biosynthetic base fluid, the aqueous solution, the organic soil, the emulsifier, the fluid loss reducer, the rigid plugging agent, the modified lignin, the graphite oxide and the calcium oxide to obtain the strong plugging biomass synthetic base drilling fluid.

[0023] Preferably, the step S) is specifically:

[0024] S1) mixing the biosynthetic base liquid with organic soil to obtain a first mixture;

[0025] S2) mixing the first mixture with an emulsifier to obtain a second mixture;

[0026] S3) mixing the second mixture with an aqueous solution to obtain a third mixture;

[0027] S4) Adding a fluid loss reducer, a rigid plugging agent, a modified lignin, graphite oxide and calcium oxide to the third mixture in sequence and mixing them to obtain a strong plugging biomass synthetic-based drilling fluid.

[0028] The invention provides a strong plugging biomass synthetic drilling fluid, comprising: 65-100 parts by weight of biomass synthetic base fluid; 0-35 parts by weight of aqueous phase solution; 3-5 parts by weight of organic soil; 4-6 parts by weight of emulsifier; 3-5 parts by weight of fluid loss reducer; 3-5 parts by weight of rigid plugging agent; 2-4 parts by weight of modified lignin; 0.5-1.5 parts by weight of graphite oxide; 2-3 parts by weight of calcium oxide; the biomass synthetic base fluid comprises one or more of dodecyl methyl ether, dodecyl ethyl ether and dodecyl butyl ether; the modified lignin comprises long-chain alkyl and amino groups. Compared with the prior art, the strong plugging biomass synthetic drilling fluid provided by the invention adopts specific content components, and each component has good interaction with each other. At the same time, the plugging property is enhanced by the scientific and reasonable combination of rigid materials, soft materials and flaky materials, so that the system has excellent lubrication, inhibition, plugging and other properties, and has the environmental advantages of green and biodegradable, which can meet the drilling construction needs of shale oil / gas horizontal wells in southwest and central plains and environmentally sensitive areas.

[0029] The experimental results show that the strong plugging biomass synthetic drilling fluid provided by the present invention has a high sealing performance at a temperature of 90°C to 180°C and a density of 0.87 g / cm 3 ~2.3g / cm 3 Within the range, the apparent viscosity is less than 66mPa·s, the medium pressure filtration loss is less than 1mL, and the high temperature and high pressure filtration loss is less than 2.8mL; and EC 50 >1×10 6 mg / L, good environmental safety, BOD5 / COD Cr Reaching 0.26, it has good biodegradability. DETAILED DESCRIPTION

[0030] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0031] The present invention provides a strong plugging biomass synthetic-based drilling fluid, comprising:

[0032]

[0033] The biomass synthesis base liquid includes one or more of dodecyl methyl ether, dodecyl ethyl ether and dodecyl butyl ether;

[0034] The modified lignin contains long-chain alkyl groups and amino groups.

[0035] The present invention uses one or more of dodecyl methyl ether, dodecyl ethyl ether and dodecyl butyl ether as the biosynthesis base liquid, wherein the structural formula of dodecyl methyl ether is CH3CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2OCH3; the structural formula of dodecyl ethyl ether is CH3CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2OCH2CH3; the structural formula of dodecyl butyl ether is CH3CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2OCH2CH3. Dodecyl methyl ether, dodecyl ethyl ether and dodecyl butyl ether all belong to plant alcohol alkyl ethers, are biomass alcohol ether organic compounds, and do not belong to mineral oils; the compound is a class of green and non-toxic substances, and the compound itself and the decomposition products have no irritating effect on the human body and the environment, have good ecological safety, and are green and non-toxic; at the same time, the dodecyl methyl ether, dodecyl ethyl ether and dodecyl butyl ether structures contain saturated long-chain fatty groups and alkyl ether groups, do not contain unsaturated bonds (ester bonds and carbon-carbon double bonds), do not belong to alkanes, have excellent inhibition, low viscosity, strong temperature resistance, safety, environmental protection characteristics, hydrolysis stability and biodegradability, and can be used as the base fluid of synthetic drilling fluids. Moreover, dodecyl methyl ether, dodecyl ethyl ether and dodecyl butyl ether have similar structures and properties, especially their polarity is equivalent, and polarity is one of the important performance indicators that affect the optimization of drilling fluid treatment agents and the construction of drilling fluid systems; only when the polarity of the mixture is within a small range of variation, can the subsequent supporting organic soil, emulsifier, filtrate reducer and other treatment agents play a stabilizing role, and then the performance of the prepared drilling fluid system can be kept stable. In addition, in accordance with JT / T617-2018 "Road Transport Rules for Dangerous Goods", dodecyl methyl ether, dodecyl ethyl ether and dodecyl butyl ether were identified, and the identification conclusion was: the product is non-dangerous goods, and the goods are not restricted by JT / T617-2018 "Road Transport Rules for Dangerous Goods". This means that the product is highly safe and environmentally friendly, and has higher transportation safety, and can be transported as general industrial goods.

[0036] In the present invention, the biosynthetic base liquid can be one of dodecyl methyl ether, dodecyl ethyl ether and dodecyl butyl ether, or a combination of two or three of them in any proportion, without special restrictions; in some embodiments provided by the present invention, the biosynthetic base liquid is specifically dodecyl methyl ether and dodecyl ethyl ether in a volume ratio of 8:2, dodecyl methyl ether and dodecyl ethyl ether in a volume ratio of 1:9, dodecyl methyl ether and dodecyl butyl ether in a volume ratio of 7:3, and dodecyl methyl ether and dodecyl butyl ether in a volume ratio of 5:5. , dodecyl methyl ether and dodecyl butyl ether in a volume ratio of 2:8, dodecyl ethyl ether and dodecyl butyl ether in a volume ratio of 6:4, or dodecyl ethyl ether and dodecyl butyl ether in a volume ratio of 5:5; in other embodiments provided by the present invention, the biosynthetic base liquid is specifically dodecyl methyl ether, dodecyl ethyl ether and dodecyl butyl ether in a volume ratio of 3:5:2; in other embodiments provided by the present invention, the biosynthetic base liquid is specifically dodecyl methyl ether, dodecyl ethyl ether and dodecyl butyl ether in a volume ratio of 6:1:3.

[0037] According to the present invention, the lubricity coefficient of the biomass synthetic base fluid is preferably 0.08 to 0.10; the kinematic viscosity of the biomass synthetic base fluid at 40°C is preferably 2.31 mm 2 / s~2.92mm 2 / s. The biomass synthetic base fluid used in the present invention has the appearance of a colorless transparent liquid or a light yellow transparent liquid, has no unsaturated bonds (ester bonds and carbon-carbon double bonds) in its structure, and has high temperature resistance and hydrolysis stability. In the present invention, the content of the biosynthetic base fluid in the strong plugging biomass synthetic base drilling fluid is preferably 85 to 95 parts by weight, more preferably 90 parts by weight; in some embodiments provided by the present invention, the content of the biosynthetic base fluid in the strong plugging biomass synthetic base drilling fluid is specifically 90 parts by weight, 85 parts by weight, 100 parts by weight, 80 parts by weight, 70 parts by weight or 75 parts by weight.

[0038] According to the present invention, the aqueous phase solution is an aqueous solution containing an aqueous phase inhibitor; the aqueous phase inhibitor can be an aqueous phase inhibitor well known to those skilled in the art without any special restrictions. In the present invention, calcium chloride and / or potassium sulfate are preferably used to enhance the inhibition of the system; the mass concentration of the aqueous phase inhibitor in the aqueous phase solution is preferably 20% to 40%; in some embodiments provided by the present invention, the mass concentration of the aqueous phase inhibitor in the aqueous phase solution is specifically 30%, 20%, 25%, 35% or 40%; the content of the aqueous phase solution in the strong plugging biomass synthetic-based drilling fluid is preferably 5 to 30 parts by weight, more preferably 5 to 20 parts by weight, and more preferably 5 to 10 parts by weight; in some embodiments provided by the present invention, the content of the aqueous phase solution in the strong plugging biomass synthetic-based drilling fluid is specifically 10 parts by weight, 15 parts by weight, 35 parts by weight, 0 parts by weight, 20 parts by weight, 30 parts by weight or 25 parts by weight.

[0039] According to the present invention, the organic soil is preferably quaternary ammonium salt modified bentonite; the carbon number of the alkyl group in the quaternary ammonium salt modified bentonite is preferably 12 to 30, more preferably 18 to 25, and even more preferably 20 to 22; in the embodiments provided by the present invention, the commercially available organic soil HFGEL-120 for drilling fluid is specifically used as an example for illustration; the content of the organic soil in the strong plugging biomass synthetic-based drilling fluid is preferably 3.5 to 4.5 parts by weight, more preferably 4 parts by weight; in some embodiments provided by the present invention, the content of the organic soil in the strong plugging biomass synthetic-based drilling fluid is specifically 3 parts by weight, 4 parts by weight or 5 parts by weight.

[0040] According to the present invention, the emulsifier preferably has a structure shown in formula (I) or is prepared from polyene polyamine, cyclic anhydride, polyformaldehyde and cardanol; the polyene polyamine is preferably triethylenetetramine and / or tetraethylenepentamine; the cyclic anhydride is preferably maleic anhydride and / or succinic anhydride; the molar ratio of the polyene polyamine, cyclic anhydride, polyformaldehyde and cardanol is preferably 1: (2-2.1): 2: (2.2-2.3): (4-5), more preferably 1: 2: 2: 2.3; the reaction temperature of polyene polyamine, cyclic anhydride, polyformaldehyde and cardanol is preferably 50°C-90°C, more preferably 60°C-80°C; the reaction time is preferably 3-5h, more preferably 4h. The emulsifier used in the present invention is a gemini emulsifier, which contains hydrophilic groups such as carboxyl, amine, hydroxyl, and lipophilic groups such as cardanol, and has good emulsifying properties. The emulsifier contains a temperature-resistant group and has a branched structure, and the emulsion has good stability. At the same time, the branched structure improves the shear force of the drilling fluid, thereby maintaining the emulsification stability of the entire drilling fluid system and maintaining good rheological properties. The content of the emulsifier in the strong plugging biomass synthetic-based drilling fluid is preferably 5 to 6 parts by weight, more preferably 5 parts by weight; in some embodiments provided by the present invention, the content of the emulsifier in the strong plugging biomass synthetic-based drilling fluid is specifically 6 parts by weight, 4 parts by weight, 5 parts by weight or 4.5 parts by weight.

[0041]

[0042] In formula (I), R1 is a C5-C12 alkyl group, preferably a C6-C10 alkyl group, and more preferably a C8 alkyl group; R2 is a C10-C18 alkyl group; and n is an integer of 1-4.

[0043] According to the present invention, the fluid loss reducer is preferably humic acid amide; using humic acid amide as a fluid loss reducer can reduce the invasion of drilling fluid filtrate into the well wall and form a good mud cake; in the embodiments provided by the present invention, humic acid amide prepared by reacting humic acid and hexadecene amine is specifically used for illustration; in some embodiments provided by the present invention, the content of the fluid loss reducer in the strong plugging biomass synthetic-based drilling fluid is specifically 3 parts by weight, 5 parts by weight, 4 parts by weight or 4.5 parts by weight.

[0044] According to the present invention, the rigid plugging agent is preferably ultrafine calcium carbonate and nano calcium carbonate; the particle size of the ultrafine calcium carbonate is preferably 500-3000 mesh; the mass ratio of the ultrafine calcium carbonate to the nano calcium carbonate is preferably (3-9):1, more preferably (4-8):1, and more preferably 6:1; in the present invention, it is further preferred that the ultrafine calcium carbonate includes 500-800 mesh ultrafine calcium carbonate, 1000-1500 mesh ultrafine calcium carbonate and 2000-3000 mesh ultrafine calcium carbonate, more preferably includes 600-800 mesh ultrafine calcium carbonate, 1100-1300 mesh ultrafine calcium carbonate and 2200-2600 mesh ultrafine calcium carbonate, and more preferably includes 800 mesh ultrafine calcium carbonate, 1200 mesh ultrafine calcium carbonate and 2500 mesh ultrafine calcium carbonate; The mass ratio of the 500-800 mesh ultrafine calcium carbonate, the 1000-1500 mesh ultrafine calcium carbonate and the 2000-3000 mesh ultrafine calcium carbonate is preferably (0.5-2): (0.5-2): 1, more preferably (0.8-1.5): (0.8-1.5): 1, further preferably (0.8-1.2): (0.8-1.2): 1, and most preferably 1: 1: 1; the present invention utilizes particle size gradings of different mesh numbers as rigid plugging agents to fill microcracks of different pore sizes, which on the one hand strengthens the plugging, and on the other hand has the effect of improving the mud cake and reducing the filtration loss; in some embodiments provided by the present invention, the content of the rigid plugging agent in the strong plugging biomass synthetic-based drilling fluid is specifically 3 parts by weight, 5 parts by weight, 4 parts by weight or 3.5 parts by weight.

[0045] According to the present invention, the modified lignin contains long-chain alkyl and amino groups. By introducing long-chain alkyl and amino groups into the lignin structure, a modified lignin with good lipophilic dispersibility can be obtained. It has both the rigid structure of lignin and the flexible lipophilic structure of the long alkyl chain. It can adhere to the gaps in the well wall to form a film, and use its own flexible deformation to squeeze into micropores and microcracks to improve the density of the plugging layer. At the same time, the lipophilic structure of the long alkyl chain also has the effect of increasing the demulsification voltage, making the drilling fluid performance more stable. In some embodiments provided by the present invention, the content of the modified lignin in the strong plugging biomass synthetic-based drilling fluid is specifically 2 parts by weight, 4 parts by weight, 3 parts by weight or 3.5 parts by weight.

[0046] According to the present invention, the particle size of the graphite oxide is preferably 100-500 mesh, more preferably 200-400 mesh, and even more preferably 300 mesh; the graphite oxide can be any graphite oxide well known to those skilled in the art, and there is no special limitation. In the present invention, the graphite oxide is specifically obtained by oxidative modification; adding graphite oxide to the drilling fluid can achieve mesh coating plugging by utilizing its large specific surface area; in some embodiments provided by the present invention, the content of the graphite oxide in the strong plugging biomass synthetic-based drilling fluid is specifically 1.5 parts by weight, 0.5 parts by weight or 1 part by weight.

[0047] The strong plugging biomass synthetic-based drilling fluid provided by the present invention achieves a strong plugging effect by utilizing the organic and scientific combination of three aspects: rigid plugging of a rigid plugging agent, film-forming plugging of modified lignin, and mesh-coated plugging of graphite oxide.

[0048] In some embodiments provided by the present invention, the content of calcium oxide in the strong plugging biomass synthetic-based drilling fluid is specifically 3 parts by weight or 2 parts by weight.

[0049] According to the present invention, the strong plugging biomass synthetic drilling fluid preferably further comprises 0.1 to 412 parts by weight of barite; the density of the barite is preferably 4.1 to 4.4 g / cm 3 , more preferably 4.3 g / cm 3 In the present invention, the content of barite added can be adjusted according to the density of the required strong plugging biomass synthetic-based drilling fluid.

[0050] According to the present invention, the density of the strong plugging biomass synthetic drilling fluid is preferably 0.87-2.3 g / cm 3 .

[0051] According to the present invention, the strong plugging biomass synthetic drilling fluid has a temperature of 90°C to 180°C and a density of 0.87 to 2.3 g / cm 3 The apparent viscosity within the range is preferably less than 66 mPa·s, the medium-pressure filtration loss is preferably less than 1 mL, and the high-temperature and high-pressure filtration loss is preferably less than 2.8 mL.

[0052] The strong plugging biomass synthetic-based drilling fluid provided by the present invention adopts components with specific contents, and the components have good interaction with each other. At the same time, the plugging property is enhanced by a scientific and reasonable combination of rigid materials, soft materials and flaky materials, so that the system has excellent lubrication, inhibition, plugging and other properties, and has the environmental protection advantages of being green and biodegradable.

[0053] The present invention also provides a method for preparing the above-mentioned strong plugging biomass synthetic-based drilling fluid, comprising the following steps: S) mixing a biosynthetic base fluid, an aqueous solution, organic soil, an emulsifier, a filtrate reducer, a rigid plugging agent, modified lignin, graphite oxide and calcium oxide to obtain a strong plugging biomass synthetic-based drilling fluid.

[0054] Among them, the present invention has no special restrictions on the sources of all raw materials, as long as they are commercially available; the contents and types of the biosynthetic base liquid, aqueous solution, organic soil, emulsifier, fluid loss reducer, rigid plugging agent, modified lignin, graphite oxide and calcium oxide are the same as described above and will not be repeated here.

[0055] The present invention has no special restrictions on the sources of the dodecyl methyl ether, dodecyl ethyl ether and dodecyl butyl ether, and commercially available products or self-made products known to those skilled in the art can be used; for example, the following preparation method can be used, specifically: chlorododecane and potassium alcoholate are heated and reacted under stirring in a closed container to obtain one or more of dodecyl methyl ether, dodecyl ethyl ether and dodecyl butyl ether; the potassium alcoholate is preferably one or more of potassium methoxide, potassium ethoxide and potassium butoxide; the molar ratio of chlorododecane to potassium alcoholate is preferably 1:1.2; the stirring speed is preferably 380-420 rpm; the reaction temperature is preferably 110°C-130°C; the reaction time is preferably 10-12h.

[0056] The biosynthetic base fluid, aqueous solution, organic soil, emulsifier, fluid loss reducer, rigid plugging agent, modified lignin, graphite oxide and calcium oxide are mixed to obtain a strong plugging biomass synthetic base drilling fluid; the present invention has no special restrictions on the mixing method, and mechanical stirring or manual stirring well known to those skilled in the art can be used, and mechanical stirring is preferred in the present invention; the mixing speed is preferably 8000-10000r / min; the mixing temperature is preferably 45°C-50°C.

[0057] In the present invention, the above steps are preferably specifically as follows: S1) mixing a biosynthetic base fluid with an organic soil to obtain a first mixture; S2) mixing the first mixture with an emulsifier to obtain a second mixture; S3) mixing the second mixture with an aqueous solution to obtain a third mixture; S4) sequentially adding a fluid loss reducer, a rigid plugging agent, modified lignin, graphite oxide and calcium oxide to the third mixture to obtain a strongly plugging biomass synthetic-based drilling fluid.

[0058] Among them, the mixing speed in the step S1) is preferably 8000-10000 r / min, and the mixing time is preferably 15-20 min; the mixing speed in the step S2) is preferably 8000-10000 r / min, and the mixing time is preferably 20-30 min; the mixing speed in the step S3) is preferably 8000-10000 r / min, and the mixing time is preferably 20-30 min; the mixing speed in the step S4) is preferably 8000-10000 r / min, and the mixing time is preferably 20-30 min.

[0059] According to the present invention, after the mixing in step S4), barite is preferably added and mixed continuously to obtain a strong plugging biomass synthetic-based drilling fluid; the rotation speed of the continued mixing is preferably 8000-10000 r / min, and the continued mixing time is preferably 30-35 min.

[0060] The preparation method of the strong plugging biomass synthetic base drilling fluid provided by the present invention has simple process steps and is easy to operate. By adopting the above specific steps, various treatment agents can be fully mixed and dissolved in the biomass synthetic base fluid to form a stable emulsion.

[0061] In order to further illustrate the present invention, the following describes in detail the strong plugging biomass synthetic-based drilling fluid and the preparation method thereof provided by the present invention in combination with the embodiments.

[0062] The reagents used in the following examples are all commercially available; the volume fraction composition of the biomass synthetic base fluid used is shown in Table 1; the rigid plugging agent used in the examples is compounded from 800-mesh ultrafine calcium carbonate, 1200-mesh ultrafine calcium carbonate, 2500-mesh ultrafine calcium carbonate and nano-calcium carbonate, and the mass ratio of the 800-mesh ultrafine calcium carbonate, 1200-mesh ultrafine calcium carbonate, 2500-mesh ultrafine calcium carbonate and nano-calcium carbonate is 2:2:2:1; the organic soil used is HFGEL-120 for drilling fluid, produced by Zhejiang Fenghong New The emulsifier (model SWRH), rigid plugging agent (model OBFD-1), modified lignin (model FOM), and filtration reducer (model AOF, which is prepared by the reaction of humic acid and hexadecene mixed amine) used were all provided by the Drilling Engineering Technology Research Institute of Sinopec Zhongyuan Petroleum Engineering Co., Ltd.; the oxidized graphite plugging agent used was provided by Hebei Yangyi Graphite Products Co., Ltd.; the barite was provided by Puyang Yufei Industrial Co., Ltd.; and the oxidized asphalt used was provided by Sichuan Xinchuangneng Petroleum Engineering Technology Co., Ltd.

[0063] Table 1 Volume fraction composition of the biomass synthesis base liquid used in the following examples of the present invention

[0064]

[0065]

[0066] Example 1

[0067] (1) The strong plugging biomass synthetic-based drilling fluid provided in this embodiment is prepared according to the following raw materials by weight: 90 parts by weight of biomass synthetic base fluid (B1), 10 parts by weight of calcium chloride aqueous solution, 3 parts by weight of organic soil, 6 parts by weight of emulsifier, 3 parts by weight of fluid loss reducer, 3 parts by weight of rigid plugging agent, 2 parts by weight of modified lignin, 1.5 parts by weight of graphite oxide plugging agent, and 3 parts by weight of calcium oxide. 412 g of barite is added to every 100 mL of the above raw material mixture; wherein the mass concentration of the calcium chloride aqueous solution is 20%.

[0068] (2) The preparation method is carried out according to the following preparation steps: adding the required amount of biomass synthesis base liquid and organic soil into a stirring container and stirring for 15 to 20 minutes to obtain a first mixture; adding the required amount of emulsifier to the first mixture and stirring for 20 to 30 minutes to obtain a second mixture; adding an aqueous phase solution to the second mixture and stirring for 20 to 30 minutes to obtain a third mixture; adding a fluid loss reducer, a rigid plugging agent, a modified lignin, an oxidized graphite plugging agent, and calcium oxide to the third mixture in sequence and stirring for 20 to 30 minutes to obtain a density of 2.3 g / cm 3 A strong plugging biomass synthetic-based drilling fluid; wherein the stirring speed is 8000r / min, and the temperature of the mixture is controlled at 45°C to 50°C during the preparation process.

[0069] Example 2

[0070] (1) The strong plugging biomass synthetic-based drilling fluid provided in this embodiment is prepared according to the following raw materials in parts by weight: 85 parts by weight of biomass synthetic base fluid (B2), 15 parts by weight of potassium sulfate aqueous solution, 5 parts by weight of organic soil, 4 parts by weight of emulsifier, 5 parts by weight of fluid loss reducer, 5 parts by weight of rigid plugging agent, 4 parts by weight of modified lignin, 0.5 parts by weight of graphite oxide plugging agent, and 3 parts by weight of calcium oxide. 268 g of barite is added to every 100 mL of the above raw material mixture; wherein the mass concentration of the potassium sulfate aqueous solution is 30%.

[0071] (2) The preparation method was carried out in the same manner as in Example 1 to obtain a density of 2.0 g / cm 3 Strong plugging biomass synthetic based drilling fluid.

[0072] Example 3

[0073] (1) The strong plugging biomass synthetic-based drilling fluid provided in this embodiment is prepared according to the following raw materials by weight: 65 parts by weight of biomass synthetic base fluid (B3), 35 parts by weight of calcium chloride aqueous solution, 3 parts by weight of organic soil, 6 parts by weight of emulsifier, 5 parts by weight of fluid loss reducer, 3 parts by weight of rigid plugging agent, 3 parts by weight of modified lignin, 1 part by weight of graphite oxide plugging agent, and 3 parts by weight of calcium oxide. 125 g of barite is added to every 100 mL of the above raw material mixture; wherein the mass concentration of the calcium chloride aqueous solution is 40%.

[0074] (2) The preparation method was carried out in the same manner as in Example 1 to obtain a density of 1.6 g / cm 3 Strong plugging biomass synthetic based drilling fluid.

[0075] Example 4

[0076] (1) The strong plugging biomass synthetic-based drilling fluid provided in this embodiment is prepared according to the following raw materials in parts by weight: 100 parts by weight of biomass synthetic base fluid (B4), 3 parts by weight of organic soil, 4 parts by weight of emulsifier, 3 parts by weight of filtrate reducer, 4 parts by weight of rigid plugging agent, 3 parts by weight of modified lignin, 0.5 parts by weight of graphite oxide plugging agent, and 2 parts by weight of calcium oxide. 1.8 g of barite is added to every 100 mL of the above raw material mixture.

[0077] (2) The preparation method was carried out in the same manner as in Example 1 to obtain a density of 0.87 g / cm 3 Strong plugging biomass synthetic based drilling fluid.

[0078] Example 5

[0079] (1) The strong plugging biomass synthetic-based drilling fluid provided in this embodiment is prepared according to the following raw materials by weight: 80 parts by weight of biomass synthetic base fluid (B5), 20 parts by weight of calcium chloride aqueous solution, 4 parts by weight of organic soil, 5 parts by weight of emulsifier, 4 parts by weight of fluid loss reducer, 3 parts by weight of rigid plugging agent, 4 parts by weight of modified lignin, 1.5 parts by weight of graphite oxide plugging agent, and 2 parts by weight of calcium oxide. 91 g of barite is added to every 100 mL of the above raw material mixture; wherein the mass concentration of the calcium chloride aqueous solution is 35%.

[0080] (2) The preparation method was carried out in the same manner as in Example 1 to obtain a density of 1.4 g / cm 3 Strong plugging biomass synthetic based drilling fluid.

[0081] Example 6

[0082] (1) The strong plugging biomass synthetic-based drilling fluid provided in this embodiment is prepared according to the following raw materials by weight: 70 parts by weight of biomass synthetic base fluid (B6), 30 parts by weight of potassium sulfate aqueous solution, 3.5 parts by weight of organic soil, 4.5 parts by weight of emulsifier, 4.5 parts by weight of fluid loss reducer, 3.5 parts by weight of rigid plugging agent, 3.5 parts by weight of modified lignin, 1 part by weight of graphite oxide plugging agent, and 3 parts by weight of calcium oxide. 182 g of barite is added to every 100 mL of the above raw material mixture; wherein the mass concentration of the potassium sulfate aqueous solution is 25%.

[0083] (2) The preparation method was carried out in the same manner as in Example 1 to obtain a density of 1.8 g / cm 3 Strong plugging biomass synthetic based drilling fluid.

[0084] Example 7

[0085] (1) The strong plugging biomass synthetic-based drilling fluid provided in this embodiment is prepared according to the following raw materials by weight: 85 parts by weight of biomass synthetic base fluid (B7), 15 parts by weight of calcium chloride aqueous solution, 3 parts by weight of organic soil, 5 parts by weight of emulsifier, 4 parts by weight of fluid loss reducer, 4 parts by weight of rigid plugging agent, 3 parts by weight of modified lignin, 1 part by weight of graphite oxide plugging agent, and 2.5 parts by weight of calcium oxide, 5 g of barite is added to every 100 mL of the above raw material mixture; wherein the mass concentration of the calcium chloride aqueous solution is 30%.

[0086] (2) The preparation method was carried out in the same manner as in Example 1 to obtain a density of 1.0 g / cm 3 Strong plugging biomass synthetic based drilling fluid.

[0087] Example 8

[0088] (1) The strong plugging biomass synthetic-based drilling fluid provided in this embodiment is prepared according to the following raw materials by weight: 75 parts by weight of biomass synthetic base fluid (B8), 25 parts by weight of calcium chloride aqueous solution, 4 parts by weight of organic soil, 6 parts by weight of emulsifier, 5 parts by weight of fluid loss reducer, 3 parts by weight of rigid plugging agent, 4 parts by weight of modified lignin, 1.5 parts by weight of graphite oxide plugging agent, and 3 parts by weight of calcium oxide. 44 g of barite is added to every 100 mL of the above raw material mixture; wherein the mass concentration of calcium chloride water-soluble is 40%.

[0089] (2) The preparation method was carried out in the same manner as in Example 1 to obtain a density of 1.2 g / cm 3 Strong plugging biomass synthetic based drilling fluid.

[0090] Example 9

[0091] According to the raw material ratio and preparation steps provided in Example 2, a density of 2.0 g / cm 3 The strong plugging biomass synthetic base drilling fluid is different in that: Example 9 uses a biomass synthetic base fluid (B9).

[0092] Example 10

[0093] According to the raw material ratio and preparation steps provided in Example 2, a density of 2.0 g / cm 3 The strong plugging biomass synthetic base drilling fluid is different in that: Example 10 uses a biomass synthetic base fluid (B10).

[0094] Embodiment 11

[0095] According to the raw material ratio and preparation steps provided in Example 2, a density of 2.0 g / cm 3 The strong plugging biomass synthetic base drilling fluid is different in that: Example 11 uses a biomass synthetic base fluid (B11).

[0096] Example 12

[0097] According to the raw material ratio and preparation steps provided in Example 2, a density of 2.0 g / cm 3 A strong plugging biomass synthetic-based drilling fluid; the difference is that Example 12 uses a biomass synthetic-based fluid (B12).

[0098] Comparative Example 1

[0099] According to the preparation method provided in Example 2, a density of 2.0 g / cm 3 The strong plugging biomass synthetic drilling fluid is different in that the emulsifier added in comparative example 1 is span80.

[0100] Comparative Example 2

[0101] According to the preparation method provided in Example 2, a density of 2.0 g / cm 3 The strong plugging biomass synthetic-based drilling fluid is different in that the filtrate reducer in Comparative Example 2 is oxidized asphalt.

[0102] Comparative Example 3

[0103] According to the preparation method provided in Example 2, a density of 2.0 g / cm 3 The strong plugging biomass synthetic-based drilling fluid is different in that: Comparative Example 3 does not add rigid composite plugging agent, modified lignin and graphite oxide.

[0104] According to the method of national standard GB / T 16783.2-2012 "Field Test of Drilling Fluids in Petroleum and Natural Gas Industry Part 2: Oil-based Drilling Fluids", the various properties of the strong plugging biomass synthetic-based drilling fluids prepared in Examples 1 to 12 and Comparative Examples 1 to 3 were tested, specifically: hot rolling at 150°C and 180°C for 16 hours, and then measuring the rheological properties, API filtration loss (FL), electrical stability (ES) and high temperature and high pressure filtration loss (HTHP). The results are shown in Table 2.

[0105] Table 2 Performance data of the strong plugging biomass synthetic-based drilling fluid prepared in Examples 1 to 12 and Comparative Examples 1 to 3

[0106]

[0107]

[0108] Note: PV is plastic viscosity, YP is dynamic shear force.

[0109] As shown in Table 2, in terms of performance, the strong plugging biomass synthetic drilling fluid provided by the present invention can be used at a temperature of 150°C to 180°C and a density of 0.87 g / cm3 ~2.3g / cm 3 Within the range, the apparent viscosity is less than 66 mPa·s, the medium-pressure filtration loss is less than 1 mL, and the high-temperature and high-pressure filtration loss is less than 2.8 mL; this indicates that the strong plugging biomass synthetic-based drilling fluid of the present invention has good rheological properties, small filtration loss, little change in viscosity due to temperature, stable performance after high temperature, and can meet the needs of exploration and development.

[0110] By comparing the data of Example 2 and Comparative Examples 1 to 3, it can be seen that the specific emulsifier, fluid loss reducer and plugging agent used in the present invention have good interaction, especially the addition of the plugging agent, which not only reduces the high temperature and high pressure fluid loss reduction performance of the system, but also improves the emulsification and increases the demulsification voltage of the system, so that the drilling fluid provided by the present invention can have better performance.

[0111] According to the formulation of Example 3 of the present invention, the strong plugging biomass synthetic-based drilling fluid in Table 3 was prepared, while the prior art diesel-based drilling fluid and the prior art synthetic-based drilling fluid were prepared by replacing the base oil with 0# diesel and gas-to-liquid Saraline 185V, respectively.

[0112] The test for biological toxicity evaluation of the strong plugging biomass synthetic drilling fluid provided by the present invention is based on the national standard GB / T 15441-1995 "Determination of acute toxicity of water quality - Luminescent bacteria method" to measure and compare the toxicity of four drilling fluids; the BOD5 / COD Cr The biodegradability of the three drilling fluids was compared using a DXY-2 biological acute toxicity tester and referring to the mysid shrimp biotoxicity grading standard confirmed by the U.S. Environmental Protection Agency. The experimental results are shown in Table 3.

[0113] Table 3 Comparison of biological toxicity and degradability of drilling fluids

[0114]

[0115] It can be seen from Table 3 that the strong plugging biomass synthetic-based drilling fluid provided by the present invention has no biological toxicity, strong biodegradability, and is green and environmentally friendly; and its biodegradability is easy and meets the emission standards.

[0116] To sum up, the strong plugging biomass synthetic-based drilling fluid provided by the present invention combines the advantages of traditional mineral oil drilling fluid and existing synthetic-based cobalt drilling fluid, and also has: good plugging performance; high adhesion and cutting, strong rock carrying capacity; low biological toxicity and good environmental safety; and the preparation process is simple, and can be applied to shale gas horizontal wells, highly water-sensitive mud shale formations and other complex wells and drilling in environmentally sensitive areas.

[0117] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention, but the present invention is not limited thereto. Those skilled in the art can understand that within the technical concept of the present invention, the technical solution of the present invention can be modified, or some technical features can be combined in any other way. These modifications or combinations do not make the essence of the corresponding technical solution deviate from the spirit and scope of each implementation of the technical solution of the present invention, and should be regarded as the contents disclosed by the present invention, which belong to the protection scope of the present invention.

Claims

1. A strong plugging biomass synthetic-based drilling fluid, characterized in that: include: The biomass synthesis base liquid includes one or more of dodecyl methyl ether, dodecyl ethyl ether and dodecyl butyl ether; The modified lignin contains long-chain alkyl groups and amino groups.

2. The strong plugging biomass synthetic-based drilling fluid according to claim 1, characterized in that: The aqueous phase solution contains an aqueous phase inhibitor; the aqueous phase inhibitor is selected from calcium chloride and / or potassium sulfate; the mass concentration of the aqueous phase inhibitor in the aqueous phase solution is 20% to 40%.

3. The strong plugging biomass synthetic-based drilling fluid according to claim 1, characterized in that: The organic soil is selected from alkyl quaternary ammonium salt modified bentonite; The emulsifier has a structure shown in formula (I) or is prepared from polyene polyamine, cyclic acid anhydride, polyformaldehyde and cardanol: In formula (I), R1 is a C5-C12 alkyl group; R2 is a C10-C18 alkyl group; n is an integer of 1 to 4; The fluid loss reducer is selected from humic acid amide; The rigid plugging agent is selected from ultrafine calcium carbonate and nano calcium carbonate; the mass ratio of the ultrafine calcium carbonate to the nano calcium carbonate is (3-9):

1.

4. The strong plugging biomass synthetic-based drilling fluid according to claim 3, characterized in that: The carbon number of the alkyl group in the alkyl quaternary ammonium salt modified bentonite is 12-30.

5. The strong plugging biomass synthetic-based drilling fluid according to claim 3, characterized in that: The R1 is a C8 alkyl group; the polyene polyamine is selected from triethylenetetramine and / or tetraethylenepentamine; the cyclic acid anhydride is selected from maleic anhydride and / or succinic anhydride; the molar ratio of the polyene polyamine, cyclic acid anhydride, polyformaldehyde and cardanol is 1:(2-2.1):2:(2.2-2.3):(4-5).

6. The strong plugging biomass synthetic-based drilling fluid according to claim 3, characterized in that: The ultrafine calcium carbonate includes 500-800 mesh ultrafine calcium carbonate, 1000-1500 mesh ultrafine calcium carbonate and 2000-3000 mesh ultrafine calcium carbonate; the mass ratio of the 500-800 mesh ultrafine calcium carbonate, 1000-1500 mesh ultrafine calcium carbonate and 2000-3000 mesh ultrafine calcium carbonate is (0.5-2):(0.5-2):

1.

7. The strong plugging biomass synthetic-based drilling fluid according to claim 1, characterized in that: It also includes 0.1 to 412 parts by weight of barite.

8. The strong plugging biomass synthetic-based drilling fluid according to claim 1, characterized in that: The strong plugging biomass synthetic drilling fluid has a temperature of 90°C to 180°C and a density of 0.87 to 2.3 g / cm 3 The apparent viscosity within the range is less than 66 mPa·s, the medium-pressure filtration loss is less than 1 mL, and the high-temperature and high-pressure filtration loss is less than 2.8 mL.

9. A method for preparing the strong plugging biomass synthetic-based drilling fluid according to claim 1, characterized in that: The following steps are involved: S) mixing the biosynthetic base fluid, the aqueous solution, the organic soil, the emulsifier, the fluid loss reducer, the rigid plugging agent, the modified lignin, the graphite oxide and the calcium oxide to obtain the strong plugging biomass synthetic base drilling fluid.

10. The preparation method according to claim 9, characterized in that: The step S) is specifically: S1) mixing the biosynthetic base liquid with organic soil to obtain a first mixture; S2) mixing the first mixture with an emulsifier to obtain a second mixture; S3) mixing the second mixture with an aqueous solution to obtain a third mixture; S4) Adding a fluid loss reducer, a rigid plugging agent, a modified lignin, graphite oxide and calcium oxide to the third mixture in sequence and mixing them to obtain a strong plugging biomass synthetic-based drilling fluid.

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