A plugging agent for drilling fluid based on oil sludge, a preparation method thereof and a drilling fluid

Abstract

This application provides a method for preparing a drilling fluid plugging and sealing agent based on oily sludge, comprising the following steps: reacting oily sludge, a crosslinking agent, and a catalyst in an inert gas atmosphere to obtain a crosslinking product; reacting the crosslinking product again in an air atmosphere to obtain a modified material; and mixing the modified material with a plugging and sealing material matrix and a dispersant to obtain the final product. This application also provides an oily sludge-based drilling fluid plugging and sealing agent and a drilling fluid. Using oily sludge as raw material, this application not only solves the environmental and safety problems caused by oily sludge treatment and realizes its high-value utilization, but also features a simple treatment process. The prepared oily sludge-based drilling fluid plugging and sealing agent provides retention properties for the plugging agent, helping to improve formation plugging efficiency and pressure bearing capacity. Experimental results show that the oily sludge-based drilling fluid plugging and sealing agent provided by this application has a pressure bearing capacity of over 6 MPa in clean water or white oil at 180–200℃.

Description

Technical Field

[0001] This invention relates to the field of oil and gas drilling engineering technology, and in particular to a sludge-based drilling fluid plugging and sealing agent, its preparation method, and the drilling fluid thereof. Background Technology

[0002] During the development, gathering, transportation, and refining of petroleum, crude oil comes into contact with soil, water, or other impurities, forming highly hazardous oily sludge after long-term aging, posing potential environmental risks. The reduction, harmlessness, resource recovery, and clean treatment of oily sludge have become research hotspots. Patent CN202211621764.3 proposes using the deep oxidation characteristics of supercritical water oxidation to burn oily sludge and use the combustion heat for heating or power generation. Patent CN202223214613.4 proposes using devices such as booster pumps, high-efficiency tubular mixers, and three-phase separators to achieve oily sludge reduction and crude oil recovery; however, the high-temperature process may generate dioxins, causing serious environmental harm. Patent CN202210756630.6 proposes catalytic oxidation of oily sludge with transition metal oleates and / or transition metal linoleates to prepare petroleum-based sodium humate and biochar, but the obtained products do not remove heavy metals, still posing environmental risks.

[0003] On the other hand, with the advancement of the deep-earth strategy, the development of deep and ultra-deep wells has brought severe challenges to drilling fluid technology. Among them, the temperature resistance of drilling plugging and sealing materials has become a bottleneck restricting the development of deep oil and gas. Traditional inert bridging plugging materials, such as mica flakes and limestone powder, are difficult to "retain" or "hook" in large fractures with large widths and high vertical extensions, especially in karst caves, due to factors such as gravity settlement, fracture erosion, and wellbore pressure fluctuations. This results in low pressure-bearing capacity of the plugging layer and easy re-leakage. Patent CN202310345110.0 proposes a high-temperature resistant, low-viscosity polymer and a high-temperature resistant delayed crosslinking polymer gel plugging agent. This patent uses a low-viscosity polymer of acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, and N-acryloylmorpholine as a thickener, mixed with a specific crosslinking agent and retarder, and prepared through a thickening reaction. This polymer gel plugging agent has delayed crosslinking properties, but its temperature resistance can only reach 160℃. Summary of the Invention

[0004] In view of this, the present invention provides a sludge-based drilling fluid plugging and sealing agent, its preparation method and drilling fluid. The sludge-based drilling fluid plugging and sealing agent provided by the present invention has both bridging properties and certain "retention" properties, which helps to improve formation plugging efficiency and pressure bearing capacity, and has good temperature resistance.

[0005] This application provides a method for preparing a drilling fluid plugging and sealing agent based on oily mud, comprising the following steps:

[0006] In an inert gas atmosphere, sludge, crosslinking agent, and catalyst are mixed and reacted to obtain crosslinking products;

[0007] The crosslinking product was reacted again in an air atmosphere to obtain the modified material;

[0008] The modified material is mixed with a plugging and sealing material matrix and a dispersant to obtain a sludge-based drilling fluid plugging and sealing agent. The plugging and sealing material matrix is ​​selected from one or more of fibrous plugging and sealing materials, granular plugging and sealing materials, and sheet-like plugging and sealing materials.

[0009] In some specific implementations, the oily sludge undergoes pretreatment, which includes:

[0010] Stir the oily sludge at 60℃~80℃ and pass it through a 150-200 mesh sieve.

[0011] In some specific implementations, the oily sludge is one or more of the following: landed oily sludge, tank bottom oily sludge, and refinery oily sludge.

[0012] In some specific implementations, the crosslinking agent is selected from one or more of paraformaldehyde, paraformaldehyde, and benzaldehyde;

[0013] The catalyst is selected from one or more of p-toluenesulfonic acid and p-aminobenzenesulfonic acid;

[0014] The mass ratio of the oily sludge, catalyst, and crosslinking agent is 100:1 to 10:1 to 10.

[0015] In some specific implementations, the reaction temperature is 120℃~150℃, the pressure is 0.5MPa~1MPa, and the time is 0.5h~2h.

[0016] The reaction is carried out under stirring conditions, with a stirring speed of 100 r / min to 500 r / min.

[0017] In some specific implementations, the temperature of the second reaction is 150℃~200℃, and the time is 1h~5h.

[0018] In some specific implementations, the sealing and plugging material matrix is ​​selected from fibrous sealing and plugging materials, granular sealing and plugging materials, and sheet-like sealing and plugging materials with a mass ratio of 50-150:100-200:100-200.

[0019] The fibrous sealing and plugging material has a particle size of 50 mesh to 200 mesh; the granular sealing and plugging material has a particle size of 0.5 mm to 1.0 mm; and the sheet-like sealing and plugging material has a particle size of 0.5 mm to 1.0 mm.

[0020] The matrix of the sealing and plugging material is made of one or more of the following: limestone particles, plastic fragments, cottonseed hulls, wood chips, sawdust, and celluloid powder.

[0021] In some specific implementations, the dispersant is selected from one or more of calcium powder or silicon powder.

[0022] This application also provides a sludge-based drilling fluid plugging and sealing agent, which is prepared by the preparation method described in the above technical solution.

[0023] This application also provides a drilling fluid, including the oily mud-based drilling fluid plugging and sealing agent described in the above technical solution or the oily mud-based drilling fluid plugging and sealing agent prepared by the preparation method described in the above technical solution.

[0024] This application first reacts oily sludge, a crosslinking agent, and a catalyst in an inert gas atmosphere, and then reacts again in an air atmosphere to obtain a modified material. This modified material is then mixed with a plugging and sealing material matrix and a dispersant to obtain an oily sludge-based drilling fluid plugging and sealing agent. Using oily sludge as raw material, this application not only solves the environmental and safety problems associated with oily sludge treatment and achieves its high-value utilization, but also features a simple processing technology. The prepared oily sludge-based drilling fluid plugging and sealing agent enters the lost formation under pressure differential, providing bridging and plugging. Simultaneously, under high temperature, the surface-modified oily sludge provides certain adsorption and deformation capabilities, providing retention for the plugging agent and helping to improve formation plugging efficiency and pressure resistance. Experimental results show that the oily sludge-based drilling fluid plugging and sealing agent provided in this application has a pressure resistance of over 6 MPa in clean water or white oil at 180℃~200℃. Detailed Implementation

[0025] It should be understood that the expression “one or more of…” individually includes each of the objects described after the expression, as well as various different combinations of two or more of the described objects, unless otherwise understood from the context and usage. The expression “and / or” combined with three or more described objects should be understood to have the same meaning, unless otherwise understood from the context.

[0026] The terms “including,” “having,” or “containing,” including the use of their grammatical synonyms, should generally be understood as open-ended and non-restrictive, for example, not excluding other unstated elements or steps, unless otherwise specifically stated or understood from the context.

[0027] It should be understood that the order of the steps or the order in which certain actions are performed is not important as long as the invention remains operational. Furthermore, two or more steps or actions can be performed simultaneously.

[0028] The use of any and all instances or exemplary language such as “e.g.” or “including” in this document is merely intended to better illustrate the invention and is not intended to limit the scope of the invention unless the claims are made. No language in this specification should be construed as indicating that any unclaimed element is essential to the practice of the invention.

[0029] Furthermore, the numerical ranges and parameters used to define the present invention are approximate values, and the relevant values ​​in the specific embodiments have been presented as precisely as possible. However, any value inevitably contains standard deviations due to individual test methods. Therefore, unless explicitly stated otherwise, it should be understood that all ranges, quantities, values, and percentages used in this disclosure are modified with the word "approximately." Here, "approximately" generally means an actual value within plus or minus 10%, 5%, 1%, or 0.5% of a particular value or range.

[0030] This application provides a method for preparing a drilling fluid plugging and sealing agent based on oily mud, comprising the following steps:

[0031] In an inert gas atmosphere, sludge, crosslinking agent, and catalyst are mixed and reacted to obtain crosslinking products;

[0032] The crosslinking product was reacted again in an air atmosphere to obtain the modified material;

[0033] The modified material is mixed with a plugging and sealing material matrix and a dispersant to obtain a sludge-based drilling fluid plugging and sealing agent. The plugging and sealing material matrix is ​​selected from one or more of fibrous plugging and sealing materials, granular plugging and sealing materials, and sheet-like plugging and sealing materials.

[0034] This application uses oily sludge as raw material. First, it undergoes cross-linking treatment in an inert gas atmosphere, followed by oxidation treatment in an air atmosphere. This material is then used as a modifier to modify fibrous, granular, and sheet-like plugging and sealing materials. This not only achieves the reduction and resource utilization of oily sludge, but also produces an oily sludge-based drilling fluid plugging and sealing agent that combines bridging properties with certain "retention" properties, which helps improve formation plugging efficiency and pressure bearing capacity.

[0035] This application uses oily sludge as raw material. The oily sludge can be one or more of the following: landed oily sludge, tank bottom oily sludge, and refinery oily sludge. This application does not have any special restrictions on it.

[0036] In some specific implementations, the oily sludge is preferably pretreated, and the pretreatment includes:

[0037] Stir the oily sludge at 60℃~80℃ and pass it through a 150-200 mesh sieve.

[0038] This application first stirs the oily sludge at 60℃~80℃, preferably 65℃~75℃, for 15~30 minutes, and then passes it through a 150-200 mesh sieve to obtain a viscous oily sludge. This application does not impose any special limitations on the stirring, but the preferred stirring speed is 200 r / min~500 r / min.

[0039] This application involves mixing oily sludge, a crosslinking agent, and a catalyst in a reaction vessel and then conducting a crosslinking reaction under an inert gas atmosphere. In some specific implementations, the crosslinking agent includes, but is not limited to, paraformaldehyde, polyformaldehyde, and benzaldehyde, and may be one or more of these. When the crosslinking agent is a combination of multiple substances, this application does not have specific requirements regarding the amount of each specific substance. In some specific implementations, the catalyst includes, but is not limited to, p-toluenesulfonic acid and p-aminobenzenesulfonic acid, and may be one or more of these. When there are two catalysts, this application does not require specific amounts of each substance. In some specific implementations, the mass ratio of the oily sludge, catalyst, and crosslinking agent is 100:1 to 10:1 to 10, preferably 100:2 to 8:2 to 8. In some specific implementations, the inert gas can be a gas such as nitrogen. In some specific implementations, the temperature of the crosslinking reaction is preferably 120℃~150℃, such as 120℃, 130℃, 140℃, or 150℃; the pressure of the crosslinking reaction is preferably 0.5MPa~1MPa, such as 0.5MPa, 0.6MPa, 0.7MPa, 0.8MPa, 0.9MPa, or 1MPa; and the time of the crosslinking reaction is 0.5h~2h, preferably 1h~1.5h. In some specific implementations, the crosslinking reaction is preferably carried out under stirring conditions, and the stirring speed is preferably 100r / min~500r / min, more preferably 150r / min~300r / min.

[0040] After the crosslinking reaction is complete, air is introduced into the obtained crosslinking product to continue the reaction, thereby obtaining the modified material. In some specific implementations, the temperature of the second reaction is higher than the temperature of the crosslinking reaction, preferably 150℃~200℃, for example 150℃, 160℃, 170℃, 180℃, 190℃ or 200℃; the time of the second reaction is 1h~5h, preferably 2h~4h.

[0041] After obtaining the modified material, it is mixed with a sealing and plugging material matrix and a dispersant to obtain a sludge-based drilling fluid sealing and plugging agent. In some specific implementations, the sealing and plugging material matrix is ​​selected from one or more of fibrous sealing and plugging materials, granular sealing and plugging materials, and sheet-like sealing and plugging materials, preferably including fibrous sealing and plugging materials, granular sealing and plugging materials, and sheet-like sealing and plugging materials. In some specific implementations, the mass ratio of the fibrous sealing and plugging materials, granular sealing and plugging materials, and sheet-like sealing and plugging materials is 50-150:100-200:100-200, preferably 80-120:120-180:120-180. In some specific implementations, the particle size of the fibrous sealing and plugging material is 50-200 mesh; the particle size of the granular sealing and plugging material is 0.5mm-1.0mm; and the particle size of the sheet-like sealing and plugging material is 0.5mm-1.0mm. In some specific implementations, the material of the sealing and plugging material matrix includes, but is not limited to, limestone particles, plastic fragments, cottonseed hulls, wood chips, sawdust, and celluloid powder, and can be one or more of these. When it is a combination of multiple substances, this application does not impose any special restrictions on the proportion of each specific substance. In some specific implementations, the dispersant includes, but is not limited to, calcium powder or silicon powder, and can be one or more of these. In some specific implementations, the mass ratio of the sludge to the sealing and plugging material matrix is ​​100:250-550, preferably 100:300-500. In some specific implementations, the amount of the dispersant is 3 wt% to 5 wt% of the oily sludge, for example, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, and 5 wt%.

[0042] Specifically, this application first adds a plugging and sealing material matrix to the modified material, then adds a dispersant and mixes them evenly. In some specific implementations, the mixing is carried out at 150℃~200℃, that is, after obtaining the modified material, no cooling is performed, and the plugging and sealing material matrix and dispersant are directly added and mixed. After uniform mixing, the resulting product is cooled to room temperature to obtain the oily mud-based drilling fluid plugging and sealing agent.

[0043] This application also provides a sludge-based drilling fluid plugging and sealing agent, prepared by the preparation method described in the above technical solution. Specifically, the sludge-based drilling fluid plugging and sealing agent includes a plugging and sealing material matrix, a dispersant, and an oil sludge modifier that has undergone crosslinking treatment and oxidation. Specific materials and preparation processes are described above and will not be repeated here.

[0044] This application also provides a drilling fluid, including the oily mud-based drilling fluid plugging and sealing agent described in the above technical solution or the oily mud-based drilling fluid plugging and sealing agent prepared by the preparation method described in the above technical solution.

[0045] In some specific implementations, the drilling fluid may also include white oil, flow pattern regulator, barite, etc. This application does not impose any special restrictions on the specific substances and amounts of each raw material, and those skilled in the art can select them as needed.

[0046] This application first reacts oily sludge, a crosslinking agent, and a catalyst in an inert gas atmosphere, and then reacts again in an air atmosphere to obtain a modified material. This modified material is then mixed with a plugging and sealing material matrix and a dispersant to obtain an oily sludge-based drilling fluid plugging and sealing agent. Using oily sludge as raw material, this application not only solves the environmental and safety problems associated with oily sludge treatment and achieves its high-value utilization, but also features a simple processing technology. The prepared oily sludge-based drilling fluid plugging and sealing agent enters the lost formation under pressure differential, providing bridging and plugging. Simultaneously, under high temperature, the surface-modified oily sludge provides certain adsorption and deformation capabilities, providing retention for the plugging agent and helping to improve formation plugging efficiency and pressure resistance. Experimental results show that the oily sludge-based drilling fluid plugging and sealing agent provided in this application has a pressure resistance of over 6 MPa in clean water or white oil at 180℃~200℃.

[0047] The following examples further illustrate the oily mud-based drilling fluid plugging and sealing agent, its preparation method, and the drilling fluid provided in this application.

[0048] Example 1

[0049] Stir the fallen oily sludge at 80℃ for 15 minutes and pass it through a 150-mesh sieve. Take 100g of the sieved fallen oily sludge into a reactor, add 1g of p-toluenesulfonic acid and 5g of paraformaldehyde, and stir for 2 hours at 120℃ under a nitrogen atmosphere with a rotation speed of 200r / min, a reaction pressure of 0.5Mpa, and a stirring speed of 0.5Mpa. Then, introduce air into the reactor, raise the temperature to 150℃, and keep it at that temperature for 5 hours. Then, add 100g of 100-150 mesh fibrous material, 150g of 0.5-1.0mm granular material, and 150g of 0.5-1.0mm flake material, add 3% calcium powder, stir evenly, and cool to room temperature to obtain the oily sludge-based drilling fluid sealing agent of the present invention, denoted as CLA-1.

[0050] Example 2

[0051] Stir the oily sludge at the bottom of the tank at 60℃ for 30 minutes, then pass it through a 200-mesh sieve. Take 100g of the sieved oily sludge from the bottom of the tank into a reactor, add 5g of p-aminosulfonic acid, 5g of paraformaldehyde, and 5g of benzaldehyde, and stir the mixture at 150r / min, 1MPa, and 150℃ for 0.5h under a nitrogen atmosphere. Then, introduce air into the reactor, heat it to 200℃, and maintain the temperature for 1h. Add 100g of 100-150 mesh fibrous material, 150g of 0.5-1.0mm granular material, and 150g of 0.5-1.0mm sheet-like sealing and plugging material, add 5% calcium powder, stir evenly, and cool to room temperature to obtain the oily sludge-based drilling fluid sealing and plugging agent of this invention, denoted as CLA-2.

[0052] Example 3

[0053] Stir the oily sludge at the bottom of the tank at 70℃ for 20 minutes, then pass it through a 180-mesh sieve. Take 100g of the sieved oily sludge from the bottom of the tank into a reactor, add 8g of p-aminosulfonic acid and 8g of benzaldehyde, and stir for 1 hour at 130℃ under a nitrogen atmosphere with a rotation speed of 170r / min, a reaction pressure of 0.8MPa, and a stirring speed of 130℃. Then, introduce air into the reactor, raise the temperature of the reactor to 180℃, and maintain the temperature for 3 hours. Add 100g of 100-150 mesh fibrous material, 150g of 0.5-1.0mm granular material, and 150g of 0.5-1.0mm sheet-like sealing and plugging material, add 4% silica powder, stir evenly, and cool to room temperature to obtain the oily sludge-based drilling fluid sealing and plugging agent of the present invention, denoted as CLA-3.

[0054] The above detailed description of the preparation process of the sealant of the present invention is for illustrative purposes only and is not intended to limit the technical solutions described in the embodiments of the present invention. Those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention to achieve the same technical effects. Any modifications or substitutions that meet the usage requirements are within the protection scope of the present invention.

[0055] Pressure resistance test:

[0056] Sealing and plugging slurry formula: Water + 0.5% sodium bentonite powder + 40% oily mud-based drilling fluid sealing and plugging agent + barite density to 1.80 g / cm³ 3 ;or:

[0057] White oil + 0.5% organic clay powder + 40% oily mud-based drilling fluid plugging agent + barite density adjusted to 1.80 g / cm³ 3 .

[0058] The pressure-bearing capacity of plugging and sealing at 180℃, 190℃, and 200℃ in Examples 1-3 was tested using a high-pressure fracture core flow device. The results are shown in Table 1.

[0059] Table 1. Test Results of Pressure Bearing Capacity of Oily Sludge-Based Drilling Fluid Plugging and Leak-Plugging Agent

[0060]

[0061] The above results indicate that the oily sludge-based drilling fluid plugging and sealing agent obtained according to the preparation method described in this invention has a pressure resistance of over 6 MPa in clean water or white oil at 180–200°C. The plugging agent preparation process is simple, which not only helps to solve the potential environmental pollution problems of oily sludge but also realizes its high-value utilization.

[0062] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a drilling fluid plugging and sealing agent based on oily mud, comprising the following steps: In an inert gas atmosphere, sludge, crosslinking agent, and catalyst are mixed and reacted to obtain crosslinking products; The crosslinking product was reacted again in an air atmosphere to obtain the modified material; The modified material is mixed with a plugging and sealing material matrix and a dispersant to obtain a sludge-based drilling fluid plugging and sealing agent. The plugging and sealing material matrix is ​​selected from one or more of fibrous plugging and sealing materials, granular plugging and sealing materials, and sheet-like plugging and sealing materials.

2. The production method according to claim 1, characterized by, The oily sludge undergoes pretreatment, which includes: Stir the oily sludge at 60℃~80℃ and pass it through a 150-200 mesh sieve.

3. The production method according to claim 2, characterized by, The oily sludge is one or more of the following: ground-borne oily sludge, tank bottom oily sludge, and refinery oily sludge.

4. The method of claim 1, wherein, The crosslinking agent is selected from one or more of trioxymethylene, paraoxymethylene and benzaldehyde; The catalyst is selected from one or more of p-toluenesulfonic acid and p-aminobenzenesulfonic acid; The mass ratio of the oily sludge, catalyst, and crosslinking agent is 100:1 to 10:1 to 10.

5. The preparation method according to claim 4, characterized in that, The reaction temperature is 120℃~150℃, the pressure is 0.5MPa~1MPa, and the time is 0.5h~2h; The reaction is carried out under stirring conditions, with a stirring speed of 100 r / min to 500 r / min.

6. The preparation method according to claim 1, characterized in that, The temperature for the second reaction is 150℃~200℃, and the time is 1h~5h.

7. The preparation method according to claim 1, characterized in that, The sealing and plugging material matrix is ​​selected from fibrous sealing and plugging materials, granular sealing and plugging materials and sheet-like sealing and plugging materials with a mass ratio of 50-150:100-200:100-200. The fibrous sealing and plugging material has a particle size of 50 mesh to 200 mesh; the granular sealing and plugging material has a particle size of 0.5 mm to 1.0 mm; and the sheet-like sealing and plugging material has a particle size of 0.5 mm to 1.0 mm. The matrix of the sealing and plugging material is made of one or more of the following: limestone particles, plastic fragments, cottonseed hulls, wood chips, sawdust, and celluloid powder.

8. The preparation method according to claim 7, characterized in that, The dispersant is selected from one or more of calcium powder or silicon powder.

9. A sludge-based drilling fluid plugging and sealing agent, prepared by the preparation method described in any one of claims 1 to 8.

10. A drilling fluid comprising the oily mud-based drilling fluid plugging and sealing agent according to claim 9 or the oily mud-based drilling fluid plugging and sealing agent prepared by any one of claims 1 to 8.

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