Biodiesel drilling fluid and preparation method and application thereof

Abstract

The present application provides a kind of biodiesel drilling fluid and its preparation method and application, the biodiesel drilling fluid includes the combination of water phase, oil phase, emulsifier, wetting agent, organic soil, filtrate reducer and quicklime, and the oil phase is biodiesel;With the biodiesel as oil phase, water phase and other additives are matched, so that the biodiesel drilling fluid obtained has the advantages of environmental protection, low price, low biological toxicity and easy degradation;And under the low addition amount of emulsifier, stable water-in-oil emulsion can still be formed, and it also has the advantages of low oil-water ratio, high viscosity and shear, strong rock-carrying capacity, good rheological property and good suspension stability.

Description

Technical Field

[0001] This invention belongs to the field of drilling fluid technology, specifically relating to a biodiesel drilling fluid, its preparation method, and its application. Background Technology

[0002] Oil-based drilling fluids possess advantages such as strong inhibition, good lubrication, protection of oil and gas reservoirs, and low filtration loss, and are widely used in the construction of high-temperature deep wells, highly deviated directional wells, horizontal wells, and various complex well sections. Oil-based drilling fluids generally use oil as the continuous phase and water as the dispersed phase, with appropriate additions of emulsifiers, wetting agents, oleophilic colloids, and weighting agents to form a stable emulsion system. Currently, commonly used base fluid systems mainly include diesel (0#), mineral oil (white oil), gas grease, and synthetic base fluids. The aqueous phase system generally uses calcium chloride brine. Emulsifiers are key components in the formulation of oil-based drilling fluids; their main function is to reduce the interfacial tension between the oil and water liquids, forming a robust interfacial film and increasing the viscosity of the outer phase to form a stable emulsion. Oleophilic colloids, mainly asphalt and organic clay, are generally dispersed in the oil phase to increase the viscosity of the oil-based drilling fluid, reducing filtration loss and suspending barite.

[0003] CN114806518A discloses an oil-based drilling fluid composition and an oil-based drilling fluid; the oil-based drilling fluid composition includes an oil phase and an aqueous phase, wherein the oil phase is 35# diesel oil. Based on a total mass of 100 parts for the oil and aqueous phases, the oil-based drilling fluid further includes: 2.0–3.5 parts of a primary emulsifier, 0.2–0.4 parts of a secondary emulsifier, 2.0–4.0 parts of a wetting agent, 0.4–1.0 parts of an organo-earth, and 1.0–3.0 parts of a reducing agent. The invention uses 1.0 to 2.0 parts of calcium oxide or calcium hydroxide as a base oil, which is low in pour point and can adapt to low temperature environment. This not only solves the problem that the consistency of oil-based drilling fluid increases and the rheological properties deteriorate due to the thickening of the oil phase in low temperature environment, making it impossible to formulate, but also meets the problem that it becomes thinner (viscosity and shear force decrease) due to the increase of temperature under high temperature conditions (180℃).

[0004] However, the aforementioned common oil-based drilling fluids with diesel, white oil, etc. as base oils have problems such as high cost and easy environmental pollution. In addition, common oil-based drilling fluid systems also have the problem of difficult rheological control, which limits the use of oil-based drilling fluids.

[0005] Therefore, developing an environmentally friendly, low-cost, and easily rheologically controllable biodiesel drilling fluid is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a biodiesel drilling fluid, its preparation method, and its application. The biodiesel drilling fluid comprises a combination of an aqueous phase, an oil phase, an emulsifier, a wetting agent, organic clay, a filtration reducer, and quicklime. By selecting biodiesel as the oil phase, the resulting oil drilling fluid has the advantages of being environmentally friendly, low-cost, and having easily controllable rheological properties. It also features high viscosity-shearing capacity, strong rock-carrying capacity, good rheological properties, and good suspension stability.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a biodiesel drilling fluid comprising a combination of an aqueous phase, an oil phase, an emulsifier, a wetting agent, an organic clay, a filtration reducer, and quicklime.

[0009] The oil phase is biodiesel.

[0010] The biodiesel drilling fluid provided by this invention comprises a combination of an aqueous phase, an oil phase, an emulsifier, a wetting agent, an organoclay, a filtration reducer, and quicklime. Biodiesel is used as the oil phase. Biodiesel is produced by chemically processing waste edible oil and methanol or ethanol, and has the advantage of lower price compared to white oil and diesel. Therefore, the oil-based drilling fluid prepared using the biodiesel has the advantage of lower price than drilling fluids prepared with diesel or white oil, thus effectively reducing the application cost of drilling fluids. Furthermore, the biodiesel has the advantages of a high flash point, easy storage and transportation, and easy biodegradability. Therefore, the biodiesel drilling fluid prepared using it also has the advantages of low biotoxicity and easy degradation. Simultaneously, by combining the biodiesel with the aqueous phase, emulsifier, wetting agent, organoclay, filtration reducer, and quicklime, a stable water-in-oil emulsion can still be formed even with a low emulsifier addition amount, exhibiting advantages such as low oil-water ratio, high viscosity-shearing capacity, strong rock-carrying capacity, good rheological properties, and good suspension stability.

[0011] Preferably, the volume ratio of the aqueous phase to the oil is (10-45):(55-90), such as 10:90, 20:80, 30:70, 40:60, or 50:50.

[0012] Preferably, the aqueous phase is a calcium chloride solution.

[0013] Preferably, the calcium chloride solution contains 20% to 50% by mass, for example, 25%, 30%, 35%, 40% or 45%, and specific values ​​between the above values ​​are not exhaustively listed here for space limitations and for the sake of brevity.

[0014] Preferably, based on a total volume of 100 mL for the aqueous and oil phases, the amount of emulsifier added is 1.5 to 4.5 g, for example, 2 g, 2.5 g, 3 g, 3.5 g, or 4 g, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0015] Preferably, the emulsifier comprises a combination of fatty acid sorbitan ester nonionic surfactants and fatty acid alcohol amine nonionic surfactants.

[0016] As a preferred technical solution of the present invention, selecting a combination of fatty acid sorbitan ester nonionic surfactants and fatty acid alcohol amine nonionic surfactants as emulsifiers can make the generated emulsion system more stable, thereby making the prepared drilling fluid have better rheological properties.

[0017] Preferably, the mass ratio of the fatty acid sorbitan ester nonionic surfactant to the fatty acid alcohol amine nonionic surfactant is 1:(1-2.5), for example, 1:1.2, 1:1.4, 1:1.6, 1:1.8, 1:2, 1:2.2 or 1:2.4, etc.

[0018] Preferably, the fatty acid sorbitan ester nonionic surfactant includes any one or a combination of at least two of sorbitan monooleate, sorbitan trioleate, or sorbitan monostearate.

[0019] Preferably, the fatty acid alcohol amine nonionic surfactant includes any one or a combination of at least two of oleic acid diethanolamine, coconut oil diethanolamine, oleic acid triethanolamine, or oleic acid monoethanolamine.

[0020] Preferably, based on a total volume of 100 mL for the aqueous and oil phases, the amount of wetting agent added is 0.2–1 g, for example, 0.3 g, 0.4 g, 0.5 g, 0.6 g, 0.7 g, 0.8 g, or 0.9 g, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0021] Preferably, the wetting agent comprises dodecyltrimethylammonium bromide and / or polyoxypropylene stearate.

[0022] Preferably, based on a total volume of 100 mL for the aqueous and oil phases, the amount of organic soil added is 1 to 4 g, for example, 1.5 g, 2 g, 2.5 g, 3 g, or 3.5 g, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific values ​​included in the range.

[0023] Preferably, based on a total volume of 100 mL for the aqueous and oil phases, the amount of the filtration loss reducing agent added is 1 to 5 g, for example, 1.5 g, 2 g, 2.5 g, 3 g, 3.5 g, 4 g, or 4.5 g, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0024] Preferably, the filtration loss reducing agent comprises humic acid amide and / or oxidized bitumen.

[0025] Preferably, based on a total volume of 100 mL for the aqueous and oil phases, the amount of quicklime added is 1 to 3 g, for example, 1.2 g, 1.4 g, 1.6 g, 1.8 g, 2 g, 2.2 g, 2.4 g, 2.6 g, or 2.8 g, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific values ​​included in the range.

[0026] Preferably, the biodiesel drilling fluid also includes a weighting agent.

[0027] It should be noted that the weighting agent is an optional component, and its amount added is determined according to the density requirements of the drilling fluid.

[0028] Preferably, the weighting agent includes barite and / or lime powder.

[0029] In a second aspect, the present invention provides a method for preparing biodiesel drilling fluid as described in the first aspect, the method comprising the following steps:

[0030] (1) Mix the oil phase, emulsifier and wetting agent to obtain mixture A;

[0031] (2) Mix the mixture A obtained in step (1) with the aqueous phase to obtain mixture B;

[0032] (3) Mix the mixture B obtained in step (2), organic soil, filtration reducer, quicklime and optionally weighting agent to obtain the biodiesel drilling fluid.

[0033] The method for preparing biodiesel drilling fluid according to the present invention first mixes the oil phase, emulsifier and wetting agent, and then adds the aqueous phase to obtain a relatively stable water-in-oil emulsion. After the stable water-in-oil emulsion is formed, solid particles such as organic clay, filtration loss reducer, lime and optional weighting agent are added respectively. The water-in-oil emulsion is uniformly dispersed by stirring and mixing to form a stable biodiesel drilling fluid.

[0034] Preferably, the mixing time in steps (1) to (3) is 20 to 30 minutes each, for example 21 minutes, 22 minutes, 23 minutes, 24 minutes, 25 minutes, 26 minutes, 27 minutes, 28 minutes or 29 minutes, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0035] Preferably, the mixing in steps (1) to (3) is carried out independently at a speed of 10,000 to 12,000 rpm (e.g., 10,200 rpm, 10,400 rpm, 10,600 rpm, 10,800 rpm, 11,000 rpm, 11,200 rpm, 11,400 rpm, 11,600 rpm or 11,800 rpm, etc.).

[0036] As a preferred technical solution of the present invention, the present invention uses a mixing process with a stirring speed of 10,000 to 12,000 rpm to form a stable water-in-oil emulsion from immiscible oil and water phases under the action of emulsifiers and wetting agents. The higher the mixing speed, the more beneficial it is to disperse the aqueous phase into smaller droplets, and the higher the stability of the emulsion. At the same time, high-speed stirring and mixing also facilitates the uniform dispersion of solid particles such as oleophilic colloids, filtration loss reducers, lime, and optional weighting agents in the emulsion, thereby forming a stable oil-based drilling fluid.

[0037] Thirdly, the present invention provides an application of the biodiesel drilling fluid as described in the first aspect in deep wells, highly deviated directional wells, or horizontal wells.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] (1) The biodiesel drilling fluid provided by the present invention comprises a combination of an aqueous phase, an oil phase, an emulsifier, a wetting agent, an organic clay, a filtration loss reducer and quicklime, wherein the oil phase is biodiesel. With the biodiesel as the oil phase, the drilling fluid can still form a stable water-in-oil emulsion with a low amount of emulsifier added, and the resulting drilling fluid has the advantages of stable rheological properties, good emulsion stability, and low filtration loss at high temperature and high pressure. It also has the advantages of low oil-water ratio, high viscosity and shearing, strong rock carrying capacity, good rheological properties and good suspension stability.

[0040] (2) The biodiesel drilling fluid provided by the present invention also has good safety and environmental protection; and because the biodiesel has the advantages of high flash point and easy storage and transportation, the biodiesel drilling fluid made therefrom is easy to biodegrade and has the advantages of low biotoxicity and easy degradation.

[0041] (3) Since the biodiesel is an ester biodiesel, which is made from waste edible oil and methanol or ethanol through chemical processing, it has a price advantage compared to white oil and diesel. Therefore, the low oil-to-water ratio drilling fluid prepared with biodiesel has a lower price than the drilling fluid prepared with diesel or white oil, which can reduce the application cost of drilling fluid. Detailed Implementation

[0042] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0043] The following is some information about the raw materials involved in the specific embodiments of this invention:

[0044] Biodiesel: sourced from Tangshan Jinlihai Company, is a type of fatty acid ethyl ester;

[0045] White oil: sourced from Shandong Taichang Petrochemical Technology Co., Ltd., and is No. 3 white oil;

[0046] Diesel fuel: sourced from China National Petroleum Corporation (CNPC), grade 0# diesel.

[0047] Example 1

[0048] A biodiesel drilling fluid, comprising an aqueous phase, an oil phase, an emulsifier, a wetting agent, an organic clay, a filtration reducer, quicklime, and a weighting agent;

[0049] The volume ratio of the oil phase to the water phase is 55:45, the water phase is a 30% calcium chloride solution, and the oil phase is biodiesel.

[0050] Based on a total volume of 100 mL for the oil and aqueous phases, the following amounts were added: 4.5 g of emulsifier (composed of sorbitan monooleate and diethanolamine oleate in a mass ratio of 1:2); 1.8 g of wetting agent (dodecyltrimethylammonium bromide); 2 g of organoaluminum; 3 g of filtration loss reducer (humic acid amide); and 2.5 g of quicklime.

[0051] The method for preparing biodiesel drilling fluid provided in this embodiment includes the following steps:

[0052] (1) Mix the oil phase, emulsifier and wetting agent under stirring at 11000 rpm for 20 min to obtain mixture A;

[0053] (2) Mix the mixture A obtained in step (1) and the aqueous phase for another 20 minutes under stirring at 11000 rpm to obtain mixture B;

[0054] (3) The mixture B obtained in step (2), organic soil, filtration loss reducer, and quicklime were mixed for 20 minutes under stirring at 11,000 rpm. Finally, a weighting agent was added to adjust the density of the drilling fluid to 2.0 g / cm³. 3 Stir at high speed for 30 minutes to obtain the biodiesel drilling fluid.

[0055] Example 2

[0056] A biodiesel drilling fluid, comprising an aqueous phase, an oil phase, an emulsifier, a wetting agent, an organic clay, a filtration reducer, quicklime, and a weighting agent;

[0057] The volume ratio of the oil phase to the water phase is 55:45, the water phase is a 30% calcium chloride solution, and the oil phase is biodiesel.

[0058] Based on a total volume of 100 mL for the oil and aqueous phases, the following amounts were added: 3 g of emulsifier (composed of sorbitan monooleate and diethanolamine oleate in a 1:1 mass ratio); 1.8 g of wetting agent (dodecyltrimethylammonium bromide); 2 g of organoaluminum; 3 g of filtration loss reducer (humic acid amide); and 2.5 g of quicklime.

[0059] The method for preparing biodiesel drilling fluid provided in this embodiment includes the following steps:

[0060] (1) Mix the oil phase, emulsifier and wetting agent under stirring at 12000 rpm for 20 min to obtain mixture A;

[0061] (2) Mix the mixture A obtained in step (1) and the aqueous phase for another 20 minutes under stirring at a speed of 12000 rpm to obtain mixture B;

[0062] (3) The mixture B obtained in step (2), organic soil, filtration loss reducer, and quicklime were mixed for 20 minutes under stirring at 12000 rpm. Finally, a weighting agent was added to adjust the density of the drilling fluid to 2.0 g / cm³. 3 Stir at high speed for 30 minutes to obtain the biodiesel drilling fluid.

[0063] Example 3

[0064] A biodiesel drilling fluid, comprising an aqueous phase, an oil phase, an emulsifier, a wetting agent, an organic clay, a filtration reducer, quicklime, and a weighting agent;

[0065] The volume ratio of the oil phase to the water phase is 55:45, the water phase is a 30% calcium chloride solution, and the oil phase is biodiesel.

[0066] Based on a total volume of 100 mL for the oil and aqueous phases, the following amounts were added: 4.5 g of emulsifier (composed of sorbitan monooleate and diethanolamine oleate in a mass ratio of 1:2.5); 1.8 g of wetting agent (dodecyltrimethylammonium bromide); 2 g of organoaluminum; 3 g of filtration loss reducer (humic acid amide); and 2.5 g of quicklime.

[0067] The method for preparing biodiesel drilling fluid provided in this embodiment includes the following steps:

[0068] (1) Mix the oil phase, emulsifier and wetting agent under stirring at 10000 rpm for 20 min to obtain mixture A;

[0069] (2) Mix the mixture A obtained in step (1) and the aqueous phase for 20 minutes under stirring at a speed of 10000 rpm to obtain mixture B;

[0070] (3) The mixture B obtained in step (2), organic soil, filtration loss reducer, and quicklime were mixed for 20 minutes under stirring at 10,000 rpm. Finally, a weighting agent was added to adjust the density of the drilling fluid to 2.0 g / cm³. 3 Stir at high speed for 30 minutes to obtain the biodiesel drilling fluid.

[0071] Example 4

[0072] A biodiesel drilling fluid differs from Example 1 only in that it does not contain sorbitan monooleate and the emulsifier is only diethanolamine oleate. The other components, dosages, and preparation methods are the same as in Example 1.

[0073] Example 5

[0074] A biodiesel drilling fluid differs from Example 1 only in that it does not contain diethanolamine oleate, and the emulsifier is only sorbitan monooleate. The other components, dosages, and preparation methods are the same as in Example 1.

[0075] Comparative Example 1

[0076] An oil-based drilling fluid differs from Example 1 only in that white oil is used instead of bio-based diesel oil; all other components, dosages, and preparation methods are the same as in Example 1.

[0077] Comparative Example 2

[0078] An oil-based drilling fluid differs from Example 1 only in that diesel fuel is used instead of bio-based diesel fuel; all other components, dosages, and preparation methods are the same as in Example 1.

[0079] Performance testing:

[0080] First, the drilling fluid was tested at 50°C. Then, the drilling fluid was placed in a high-temperature aging tank and aged at 180°C for 16 hours. After cooling to 50°C, the performance of the aged drilling fluid was tested.

[0081] (1) Plastic viscosity: The test was conducted in accordance with GB / T 16783.2 Field testing of drilling fluids for the oil and gas industry - Part 2: Oil-based drilling fluids;

[0082] (2) Dynamic shear force: The test shall be conducted in accordance with GB / T 16783.2 Field testing of drilling fluids for oil and gas industry - Part 2: Oil-based drilling fluids;

[0083] (3) Initial / Final cut: Refer to GB / T 16783.2 Field testing of drilling fluids for oil and gas industry - Part 2: Oil-based drilling fluids for testing;

[0084] (4) High temperature and high pressure filtration loss: The test shall be conducted in accordance with GB / T 16783.2 Field testing of drilling fluids for oil and gas industry - Part 2: Oil-based drilling fluids;

[0085] (5) Demulsification voltage: The test shall be conducted in accordance with GB / T 16783.2 Field test of drilling fluids for oil and gas industry - Part 2: Oil-based drilling fluids.

[0086] The drilling fluids provided in Examples 1-5 and Comparative Examples 1-2 were tested according to the above test methods. The test results are shown in Table 1.

[0087] Table 1

[0088]

[0089] According to the data in Table 1:

[0090] The bio-based drilling fluids provided in Examples 1-5 have a plastic viscosity of 41-72 mPa·s at 50°C, a dynamic shear force of 8-15 Pa, an initial / final shear ratio of 5 / 8-9 / 15, and a demulsification voltage of 438-965 V. At 180°C for 16 hours, the plastic viscosity is 39-63 mPa·s, the dynamic shear force is 7-12 Pa, the initial / final shear ratio is 4.5 / 7-9 / 14, the filtration loss is 2.2-6.2 mL, and the demulsification voltage is 532-843 V. Comparing the data from Example 1 and Comparative Examples 1-2 reveals that the oil-based drilling fluids prepared by replacing bio-based diesel with white oil (Comparative Example 1) or replacing bio-based diesel with diesel (Comparative Example 2) have higher plastic viscosity, lower demulsification voltage, and higher high-temperature, high-pressure filtration loss, indicating poorer rock-carrying capacity and rheological properties.

[0091] Comparing the data from Examples 1 and 4-5, it can also be found that the choice of nonionic surfactants also affects the rock-carrying capacity and rheological properties of the final oil-based drilling fluid.

[0092] The applicant declares that this invention illustrates a biodiesel drilling fluid, its preparation method, and its application through the above embodiments. However, this invention is not limited to the above embodiments, meaning that this invention does not necessarily rely on the above embodiments for implementation. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials for the product, addition of auxiliary components, and selection of specific methods, etc., all fall within the protection and disclosure scope of this invention.

Claims

1. A biodiesel drilling fluid, characterized in that, The biodiesel drilling fluid comprises a combination of an aqueous phase, an oil phase, an emulsifier, a wetting agent, an organic clay, a filtration reducer, and quicklime. The oil phase is biodiesel; The volume ratio of the aqueous phase to the oil phase is (10~45):(55~90); Based on a total volume of 100 mL for the aqueous and oil phases, the amount of emulsifier added is 1.5-4.5 g, the amount of wetting agent added is 0.2-1 g, the amount of filtration loss reducer added is 1-5 g, the amount of organic soil added is 1-4 g, and the amount of quicklime added is 1-3 g. The aqueous phase is a calcium chloride solution with a calcium chloride mass percentage of 20-50%. The emulsifier comprises a combination of fatty acid sorbitan ester nonionic surfactants and fatty acid alcohol amine nonionic surfactants; the mass ratio of the fatty acid sorbitan ester nonionic surfactants to the fatty acid alcohol amine nonionic surfactants is 1:(1.2~2.5); The fatty acid sorbitan ester nonionic surfactants include any one or a combination of at least two of sorbitan monooleate, sorbitan trioleate, or sorbitan monostearate. The fatty acid alcohol amine nonionic surfactants include any one or a combination of at least two of diethanolamine oleate, diethanolamine coconut oil, triethanolamine oleate, or monoethanolamine oleate. The wetting agent includes dodecyltrimethylammonium bromide and / or polyoxypropylene stearate; The filtration loss reducing agent includes humic acid amide and / or oxidized bitumen.

2. The biodiesel drilling fluid according to claim 1, characterized in that, The biodiesel drilling fluid also includes a weighting agent.

3. The biodiesel drilling fluid according to claim 2, characterized in that, The weighting agent includes barite and / or lime powder.

4. A method for preparing biodiesel drilling fluid as described in any one of claims 1 to 3, characterized in that, The preparation method includes the following steps: (1) Mix the oil phase, emulsifier and wetting agent to obtain mixture A; (2) Mix the mixture A obtained in step (1) with the aqueous phase to obtain mixture B; (3) Mix the mixture B obtained in step (2), organic soil, filtration reducer, quicklime and optionally weighting agent to obtain the biodiesel drilling fluid.

5. The preparation method according to claim 4, characterized in that, The mixing time for each step (1) to (3) is 20 to 30 minutes.

6. The preparation method according to claim 4, characterized in that, The mixing in steps (1) to (3) is carried out independently at a speed of 10,000 to 12,000 rpm.

7. The application of a biodiesel drilling fluid as described in any one of claims 1 to 3 in deep wells, highly deviated directional wells, or horizontal wells.

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