Oil removal treatment method for oil-based drilling cuttings
By using tertiary amine ester compounds as deoiling agents, combined with CO2 protonation and N2 deprotonation treatment, the problem of high energy consumption in oil-based drill cuttings treatment is solved, and low-cost, efficient deoiling effect and deoiling agent recycling are achieved.
Patent Information
- Application Number
- CN202510919404.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-04
- Publication Date
- 2025-09-23
AI Technical Summary
Existing oil-based drill cuttings processing technology has high energy consumption, and traditional solvent extraction relies on evaporation and condensation, resulting in high costs.
Tertiary amine ester compounds are used as degreasing agents. Solvent separation is achieved through stirring, centrifugation, CO2 protonation and N2 deprotonation, thereby reducing energy consumption and improving degreasing efficiency.
Under the premise of ensuring the degreasing effect, it can significantly reduce energy consumption and costs, reduce environmental pollution, and realize the recycling of degreasing agents.
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Abstract
Description
Technical Field
[0001] The invention relates to the technical field of oil-based drill cuttings processing, in particular to a method for deoiling oil-based drill cuttings. Background Art
[0002] Oil-based drill cuttings are a highly hazardous solid waste generated during oil and gas drilling. They originate from the oily components that adhere to the cuttings' surface when oil-based drilling fluids are used. These materials exhibit a black, viscous physical appearance and constitute a highly complex multiphase system, primarily composed of mineral oil (typically containing up to 15%-30%), alkanes and their derivatives, heavy metal ions (such as chromium, lead, and mercury), and solid particulate matter. Because oil-based drill cuttings contain significant amounts of persistent organic pollutants and heavy metals, improper disposal can lead to the erosion of these hazardous substances through rainwater into the soil and groundwater systems, causing multifaceted ecological damage. These harmful substances can inhibit plant root development and microbial community activity, while also posing a threat to human health through enrichment within the food chain. From a resource recycling perspective, the mineral oil components found in oil-based drill cuttings possess significant recovery value. These mineral oils are essential raw materials for the formulation of oil-based drilling fluids, and their recycling and reuse can significantly reduce raw material costs in drilling operations. Therefore, developing methods for the harmless and resource-based treatment of oil-based drill cuttings has significant implications for oilfield environmental protection.
[0003] The currently commonly used technology for processing oil-based drill cuttings is solvent extraction. This method uses the principle of "like dissolves like" to dissolve and separate the oil phase in the drill cuttings with an organic solvent, and then recovers the solvent and base oil through distillation. Although solvent extraction has the advantages of high oil removal efficiency and mild operating conditions, the traditional solvent extraction process relies on evaporation and condensation to achieve solvent separation, which consumes a large amount of heat energy and leads to high costs. Summary of the Invention
[0004] In order to solve the above technical problems, the present invention provides an oil-based drill cuttings degreasing method, comprising the following steps: S1: After mixing the oil-based drill cuttings and the degreaser, water is added and the mixture is continuously stirred to obtain a mixture; S2: centrifuging the mixture and taking the upper liquid phase; S3: introducing CO2 into the liquid phase for protonation treatment, separating the layers, recovering the upper oil phase, and taking the lower aqueous phase mixture; S4: introducing N2 into the aqueous phase mixture for deprotonation, separating the layers, and recovering the degreasing agent; The degreasing agent includes tertiary amine ester compounds.
[0005] Furthermore, the tertiary amine ester compound is a tertiary amine ester compound containing a tertiary carbon group.
[0006] Furthermore, the tertiary amine ester compound containing a tertiary carbon group is 2-(dimethylamino)ethyl pivalate.
[0007] Furthermore, the mass ratio of the oil-based drill cuttings to the deoiling agent is 1:(1-3).
[0008] Furthermore, the amount of water added in step S1 does not exceed 20% of the mass of the degreasing agent.
[0009] Furthermore, introducing CO2 into the liquid phase for protonation treatment includes: introducing CO2 into the liquid phase at a flux of 0.5-1.5 L / min for protonation treatment.
[0010] Furthermore, introducing N2 into the aqueous phase mixture for deprotonation treatment includes: introducing N2 into the aqueous phase mixture at a flux of 0.5-1.5 L / min for deprotonation treatment.
[0011] Furthermore, the degreasing agent also includes a stabilizer.
[0012] Furthermore, the stabilizer is saponin.
[0013] Furthermore, the mass ratio of the tertiary amine ester compound to the stabilizer in the degreasing agent is 10:(2-5).
[0014] The embodiments of the present invention have the following technical effects: The oil-based drill cuttings degreasing treatment method provided in the present application uses tertiary amine ester compounds as degreasing agents. The degreasing agents have no irritating odor, and the degreasing treatment process conditions are mild. Solvent separation can be achieved without relying on evaporation and condensation, which greatly reduces energy consumption and reduces costs. The treatment method recovers petroleum substances by protonating the degreasing agent through the introduction of carbon dioxide, and recovers and recycles the degreasing agent by deprotonating it through the introduction of nitrogen, thereby further reducing costs while ensuring the degreasing effect, and helping to reduce environmental pollution. DETAILED DESCRIPTION
[0015] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention are described clearly and completely below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are considered to be within the scope of the present invention.
[0016] In view of the problem of high energy consumption of existing oil-based drill cuttings processing technology, the present application provides an oil-based drill cuttings deoiling processing method, comprising the following steps: S1: After mixing the oil-based drill cuttings and the degreaser, water is added and the mixture is continuously stirred to obtain a mixture; Preferably, in this step, the oil-based drill cuttings and the degreaser are mixed and stirred at a speed of 500 r / min for 30 minutes, water is added, and the mixture is further mixed and stirred at a speed of 500 r / min for 100 minutes to obtain a mixture; Oil substances such as petroleum are usually adsorbed on the surface of drill cuttings particles through hydrogen bonding, van der Waals forces, etc. In this step, the oil substances are removed from the drill cuttings by stirring; S2: centrifuge the mixture and take the upper liquid phase; Preferably, the centrifugation is carried out at 3000 rpm for 5 minutes in this step. After centrifugation, the system is divided into a solid phase and a liquid phase distributed from bottom to top. The solid phase at the bottom is drill cuttings residue, and the liquid phase includes an aqueous phase and an oil phase located above the aqueous phase. The oil phase is a mixture of a degreaser and a petroleum-based substance. S3: introducing CO2 into the liquid phase for protonation treatment, separating the layers, recovering the upper oil phase, and taking the lower aqueous phase mixture; Preferably, in this step, after mixing the water phase and the oil phase in the liquid phase, CO2 is introduced for protonation treatment, so that the deoiling agent changes from lipophilic to hydrophilic. As the CO2 is introduced, the hydrophilic deoiling agent gradually enters the water phase, and the system is separated into layers. To improve efficiency, the separation can be performed by centrifugation, and the upper layer is the petroleum-based substance, which is recovered; the lower layer of the aqueous phase mixture is a mixture of water and the deoiling agent; Preferably, carbon dioxide is introduced under stirring in this step, and preferably the carbon dioxide is introduced at a flux of 0.5-1.5 L / min for 30-90 min; S4: introducing N2 into the aqueous phase mixture for deprotonation, separating the layers, and recovering the degreasing agent; N was introduced into the aqueous mixture. 2, The degreasing agent gradually changes its lipophilicity and precipitates from the water, and the system is re-stratified. The lower layer is water, which can be recycled and reused; the upper layer is the degreasing agent, which can be recycled; Preferably, nitrogen is introduced into the mixture under stirring in this step, and preferably nitrogen is introduced into the mixture at a flow rate of 0.5-1.5 L / min for 30-90 min.
[0017] The preferred degreasing agent of the present application includes tertiary amine ester compounds.
[0018] Specifically, the tertiary amine ester compound refers to an ester compound including a tertiary amine group in its structure; when the tertiary amine ester compound is mixed and stirred with oil-based drill cuttings, the oleophilic property of the tertiary amine ester compound is utilized to dissolve oily substances such as petroleum attached to the drill cutting particles; since the oleophilic degreaser is easy to automatically aggregate under the action of surface free energy, in order to avoid interference from mutual adsorption of surface substances, the present application preferably adds water and continues to stir after the oil-based drill cuttings and degreaser are mixed and stirred, so as to promote the separation of the degreaser and the petroleum substances adsorbed on the surface of the drill cuttings from the drill cuttings, so that after centrifugal stratification in step S2, the liquid phase obtained includes water, degreaser and petroleum substances; CO2 is introduced into the liquid phase, and CO2 reacts with water in the liquid phase to generate H2CO3, which ionizes to produce H + , the tertiary amine protons in the tertiary amine ester compound are converted into amine ions, thereby causing the degreasing agent to change from lipophilic to hydrophilic, enter the water phase, and obtain an aqueous phase mixture; after nitrogen is introduced into the aqueous phase mixture, the dissolved CO2 in the aqueous phase mixture is gradually discharged, and at the same time the protonated amine ions are decomposed to provide H + , completing the deprotonation treatment and converting it into a tertiary amine group. The degreaser changes from hydrophilic to lipophilic and can be recycled.
[0019] The oil-based drill cuttings degreasing treatment method provided in the present application uses tertiary amine ester compounds as degreasing agents. The degreasing agents have a low irritating odor, and the degreasing treatment process conditions are mild. Solvent separation can be achieved without relying on evaporation and condensation, which greatly reduces energy consumption and reduces costs. The treatment method recovers petroleum substances by protonating the degreasing agent through the introduction of carbon dioxide, and recovers and recycles the degreasing agent by deprotonating it through the introduction of nitrogen, thereby further reducing costs while ensuring the degreasing effect, and helping to reduce environmental pollution.
[0020] The tertiary amine ester compound can be prepared using the corresponding existing technology; specifically, when the tertiary amine ester compound is a linear tertiary amine ester compound, the tertiary amine ester compound can be prepared according to the following method: using a linear organic acid and N,N-dimethylethanolamine as raw materials, an esterification reaction is carried out under the catalysis of p-toluenesulfonic acid to obtain a tertiary amine ester compound.
[0021] Preferably, this step is prepared as follows: A linear organic acid is mixed with N,N-dimethylethanolamine, stirred and dissolved, toluene and a catalyst p-toluenesulfonic acid are added, and the mixture is reacted at 90-150° C. for 2-10 hours under an inert gas atmosphere. The mixture is then cooled to room temperature, and a sample is collected and distilled using a rotary evaporator. A sodium carbonate solution is added dropwise to the remaining solution, and the pH is simultaneously measured. When the pH is 7, ether is added to wash the organic phase, and the process is repeated three times. Finally, excess ether is removed by reduced pressure distillation, and the mixture is dehydrated using dry anhydrous magnesium chloride to obtain a degreasing agent.
[0022] In order to take into account both the reaction rate and the conversion rate, the present application preferably has a molar ratio of N,N-dimethylethanolamine to the linear organic acid of 1:(1.1-1.5), and further preferably has a mass of p-toluenesulfonic acid of 0.5%-1.0% of the total mass of the reactants, that is, the mass of p-toluenesulfonic acid is 0.5%-1.0% of the total mass of the linear organic acid and N,N-dimethylethanolamine.
[0023] In order to improve the stability of the degreasing agent, inhibit its hydrolysis and extend its cycle times, the present application prefers that the tertiary amine ester compound is a tertiary amine ester compound containing a tertiary carbon group, so as to protect the ester bond and inhibit its hydrolysis by introducing a steric hindrance structure.
[0024] The tertiary amine ester compound containing a tertiary carbon group in the present application can be prepared using tertiary carbonic acid as a raw material; specifically, it is preferably prepared using tertiary carbonic acid and N,N-dimethylethanolamine as raw materials, so that the tertiary carbonic acid can give the tertiary amine ester compound a steric hindrance structure.
[0025] Furthermore, in order to take into account the stability of the degreaser structure and the flexibility of responding to carbon dioxide / nitrogen, the present application prefers that the tertiary carbonic acid is pivalic acid, and specifically prefers that the tertiary amine ester compound containing a tertiary carbon group is 2-(dimethylamino)ethyl pivalate.
[0026] The 2-(dimethylamino)ethyl pivalate can be prepared from pivalic acid and N,N-dimethylethanolamine by an acyl chloride method, that is, pivaloyl chloride is first generated using pivaloyl acid as a raw material, and then the pivaloyl chloride is reacted with N,N-dimethylethanolamine to prepare the 2-(dimethylamino)ethyl pivalate.
[0027] In order to take into account both the degreasing effect and economy, the present application preferably uses a mass ratio of oil-based drill cuttings to degreasing agent of 1: (1-3), and further preferably 1:2.
[0028] The present application further prefers that the amount of water added in step S1 does not exceed 20% of the mass of the deoiling agent, so as to ensure the deoiling effect while taking into account the stability of the deoiling agent and improving its cyclic stability.
[0029] The degreasing agent of the present application preferably also includes a stabilizer, so as to further improve the stability of the system and reduce costs by compounding the tertiary amine ester compound with the stabilizer.
[0030] Specifically, the preferred stabilizer in the present application is saponin, which is used to repair the oil-water interface film, reduce the molecular loss of tertiary amine ester compounds, and extend the cycle life of the degreaser.
[0031] Furthermore, the present application preferably has a mass ratio of the tertiary amine ester compound to the stabilizer in the degreasing agent of 10:(2-5).
[0032] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below.
[0033] Example 1
[0034] This embodiment provides a method for processing oil-based drill cuttings, comprising the following steps: S1: Mix oil-based drill cuttings and degreaser in a mass ratio of 1:2, stir at a speed of 500 r / min for 30 minutes, add water in an amount of 10% by mass of the degreaser, and continue stirring at a speed of 500 r / min for 100 minutes to obtain a mixture; S2: The mixture was centrifuged at 3000 rpm for 5 minutes to separate into layers, obtaining drill cuttings residue in the lower layer and a liquid phase in the upper layer. The drill cuttings residue was air-dried and its oil content was measured; the liquid phase in the upper layer was collected; S3: Protonate the liquid phase by introducing carbon dioxide at a rate of 1.0 L / min for 60 min, separate the layers, recover the upper oil phase (petroleum-based substances), and remove the lower aqueous phase mixture; S4: nitrogen was introduced into the aqueous phase mixture at a flow rate of 1.0 L / min for 60 min for deprotonation treatment, the layers were separated, and the upper oil phase, i.e., the deoiling agent, was recovered.
[0035] The degreasing agent in this embodiment is 2-(dimethylamino)ethyl pivalate, which is prepared as follows: Pivalic acid is added to a dry reaction flask, cooled to 0°C in an ice bath, and SOCl2 is slowly added dropwise (addition time is greater than 30 minutes) to obtain a reactant; the molar ratio of pivalic acid to SOCl2 is 1:1.5; DMF is added to the reactant (the ratio of pivalic acid to DMF is 100 g:1 drop), the ice bath is removed, the temperature is raised to reflux (70-80°C), and stirring is performed for approximately 2 hours until no gas escapes to obtain product I; product I is subjected to reduced pressure distillation, and the fraction at 105-107°C is collected to obtain pivaloyl chloride.
[0036] Under ice bath conditions, N,N-dimethylethanolamine, triethylamine, and anhydrous DCM are added to a reaction vessel with a temperature below 5°C to obtain a reaction mixture; pivaloyl chloride is dissolved in an equal volume of anhydrous DCM and slowly added dropwise to the reaction mixture (dropping time is greater than 30 min), maintaining the temperature below 5°C; after the dropwise addition is completed, the ice bath is removed, and the mixture is stirred at room temperature for 3 hours to obtain product II; product II is filtered to obtain a filtrate; the filtrate is washed with 5% mass concentration dilute hydrochloric acid, saturated NaHCO3 solution, and saturated brine, in sequence, and then dried over anhydrous MgSO4 for 30 minutes, and then DCM is removed by rotary evaporation to obtain 2-(dimethylamino)ethyl pivalate.
[0037] The molar ratio of pivaloyl chloride, N,N-dimethylethanolamine, and triethylamine is 1:1.1:1.2; the usage ratio of N,N-dimethylethanolamine to anhydrous DCM is 1 g:10 mL.
[0038] Example 2
[0039] This embodiment provides a method for processing oil-based drill cuttings, comprising the following steps: S1: Mix oil-based drill cuttings and degreaser in a mass ratio of 1:3, stir at a speed of 500 r / min for 30 minutes, then add water in an amount of 10% by mass of the degreaser, and continue stirring at a speed of 500 r / min for 100 minutes to obtain a mixture; S2: The mixture was centrifuged at 3000 rpm for 5 minutes to separate into layers, obtaining drill cuttings residue in the lower layer and a liquid phase in the upper layer. The drill cuttings residue was air-dried and its oil content was measured; the liquid phase in the upper layer was collected; S3: Protonate the liquid phase by introducing carbon dioxide at a rate of 1.0 L / min for 60 min, separate the layers, recover the upper oil phase (petroleum-based substances), and remove the lower aqueous phase mixture; S4: nitrogen was introduced into the aqueous phase mixture at a flow rate of 1.0 L / min for 60 min for deprotonation treatment, the layers were separated, and the upper oil phase, i.e., the deoiling agent, was recovered.
[0040] The degreasing agent in this embodiment is 2-(dimethylamino)ethyl pivalate, which is prepared as follows: Pivalic acid is added to a dry reaction flask, cooled to 0°C in an ice bath, and SOCl2 is slowly added dropwise (addition time is greater than 30 minutes) to obtain a reactant; the molar ratio of pivalic acid to SOCl2 is 1:1.5; DMF is added to the reactant (the ratio of pivalic acid to DMF is 100 g:1 drop), the ice bath is removed, the temperature is raised to reflux (70-80°C), and stirring is performed for approximately 2 hours until no gas escapes to obtain product I; product I is subjected to reduced pressure distillation, and the fraction at 105-107°C is collected to obtain pivaloyl chloride.
[0041] Under ice bath conditions, N,N-dimethylethanolamine, triethylamine, and anhydrous DCM are added to a reaction vessel with a temperature below 5°C to obtain a reaction mixture; pivaloyl chloride is dissolved in an equal volume of anhydrous DCM and slowly added dropwise to the reaction mixture (dropping time is greater than 30 min), maintaining the temperature below 5°C; after the dropwise addition is completed, the ice bath is removed, and the mixture is stirred at room temperature for 3 hours to obtain product II; product II is filtered to obtain a filtrate; the filtrate is washed with 5% mass concentration dilute hydrochloric acid, saturated NaHCO3 solution, and saturated brine, in sequence, and then dried over anhydrous MgSO4 for 30 minutes, and then DCM is removed by rotary evaporation to obtain 2-(dimethylamino)ethyl pivalate.
[0042] The molar ratio of pivaloyl chloride, N,N-dimethylethanolamine, and triethylamine is 1:1.1:1.2; the usage ratio of N,N-dimethylethanolamine to anhydrous DCM is 1 g:10 mL.
[0043] Example 3
[0044] This embodiment provides a method for processing oil-based drill cuttings, comprising the following steps: S1: Mix oil-based drill cuttings and degreaser in a mass ratio of 1:1, stir at a speed of 500 r / min for 30 minutes, add water in an amount of 10% by mass of the degreaser, and continue stirring at a speed of 500 r / min for 100 minutes to obtain a mixture; S2: The mixture was centrifuged at 3000 rpm for 5 minutes to separate into layers, obtaining drill cuttings residue in the lower layer and a liquid phase in the upper layer. The drill cuttings residue was air-dried and its oil content was measured; the liquid phase in the upper layer was collected; S3: Protonate the liquid phase by introducing carbon dioxide at a rate of 1.0 L / min for 60 min, separate the layers, recover the upper oil phase (petroleum-based substances), and remove the lower aqueous phase mixture; S4: nitrogen was introduced into the aqueous phase mixture at a flow rate of 1.0 L / min for 60 min for deprotonation treatment, the layers were separated, and the upper oil phase, i.e., the deoiling agent, was recovered.
[0045] The degreasing agent in this embodiment is 2-(dimethylamino)ethyl pivalate, which is prepared as follows: Pivalic acid is added to a dry reaction flask, cooled to 0°C in an ice bath, and SOCl2 is slowly added dropwise (addition time is greater than 30 minutes) to obtain a reactant; the molar ratio of pivalic acid to SOCl2 is 1:1.5; DMF is added to the reactant (the ratio of pivalic acid to DMF is 100 g:1 drop), the ice bath is removed, the temperature is raised to reflux (70-80°C), and stirring is performed for approximately 2 hours until no gas escapes to obtain product I; product I is subjected to reduced pressure distillation, and the fraction at 105-107°C is collected to obtain pivaloyl chloride.
[0046] Under ice bath conditions, N,N-dimethylethanolamine, triethylamine, and anhydrous DCM are added to a reaction vessel with a temperature below 5°C to obtain a reaction mixture; pivaloyl chloride is dissolved in an equal volume of anhydrous DCM and slowly added dropwise to the reaction mixture (dropping time is greater than 30 min), maintaining the temperature below 5°C; after the dropwise addition is completed, the ice bath is removed, and the mixture is stirred at room temperature for 3 hours to obtain product II; product II is filtered to obtain a filtrate; the filtrate is washed with 5% mass concentration dilute hydrochloric acid, saturated NaHCO3 solution, and saturated brine, in sequence, and then dried over anhydrous MgSO4 for 30 minutes, and then DCM is removed by rotary evaporation to obtain 2-(dimethylamino)ethyl pivalate.
[0047] The molar ratio of pivaloyl chloride, N,N-dimethylethanolamine, and triethylamine is 1:1.1:1.2; the usage ratio of N,N-dimethylethanolamine to anhydrous DCM is 1 g:10 mL.
[0048] Example 4
[0049] This embodiment provides a method for processing oil-based drill cuttings, comprising the following steps: S1: Mix oil-based drill cuttings and degreaser in a mass ratio of 1:2, stir at a speed of 500 r / min for 30 minutes, add water in an amount of 10% by mass of the degreaser, and continue stirring at a speed of 500 r / min for 100 minutes to obtain a mixture; S2: The mixture was centrifuged at 3000 rpm for 5 minutes to separate into layers, obtaining drill cuttings residue in the lower layer and a liquid phase in the upper layer. The drill cuttings residue was air-dried and its oil content was measured; the liquid phase in the upper layer was collected; S3: Protonate the liquid phase by introducing carbon dioxide at a rate of 1.0 L / min for 60 min, separate the layers, recover the upper oil phase (petroleum-based substances), and remove the lower aqueous phase mixture; S4: nitrogen was introduced into the aqueous phase mixture at a flow rate of 1.0 L / min for 60 min for deprotonation treatment, the layers were separated, and the upper oil phase, i.e., the deoiling agent, was recovered.
[0050] The degreasing agent in this embodiment is a mixture of 2-(dimethylamino)ethyl pivalate and saponin in a mass ratio of 10:3. 2-(dimethylamino)ethyl pivalate is prepared according to the following method: Pivalic acid is added to a dry reaction flask, cooled to 0°C in an ice bath, and SOCl2 is slowly added dropwise (addition time is greater than 30 minutes) to obtain a reactant; the molar ratio of pivalic acid to SOCl2 is 1:1.5; DMF is added to the reactant (the ratio of pivalic acid to DMF is 100 g:1 drop), the ice bath is removed, the temperature is raised to reflux (70-80°C), and stirring is performed for approximately 2 hours until no gas escapes to obtain product I; product I is subjected to reduced pressure distillation, and the fraction at 105-107°C is collected to obtain pivaloyl chloride.
[0051] Under ice bath conditions, N,N-dimethylethanolamine, triethylamine, and anhydrous DCM are added to a reaction vessel with a temperature below 5°C to obtain a reaction mixture; pivaloyl chloride is dissolved in an equal volume of anhydrous DCM and slowly added dropwise to the reaction mixture (dropping time is greater than 30 min), maintaining the temperature below 5°C; after the dropwise addition is completed, the ice bath is removed, and the mixture is stirred at room temperature for 3 hours to obtain product II; product II is filtered to obtain a filtrate; the filtrate is washed with 5% mass concentration dilute hydrochloric acid, saturated NaHCO3 solution, and saturated brine, in sequence, and then dried over anhydrous MgSO4 for 30 minutes, and then DCM is removed by rotary evaporation to obtain 2-(dimethylamino)ethyl pivalate.
[0052] The molar ratio of pivaloyl chloride, N,N-dimethylethanolamine, and triethylamine is 1:1.1:1.2; the usage ratio of N,N-dimethylethanolamine to anhydrous DCM is 1 g:10 mL.
[0053] Example 5
[0054] This embodiment provides a method for processing oil-based drill cuttings, comprising the following steps: S1: Mix oil-based drill cuttings and degreaser in a mass ratio of 1:2, stir at a speed of 500 r / min for 30 minutes, add water in an amount of 10% by mass of the degreaser, and continue stirring at a speed of 500 r / min for 100 minutes to obtain a mixture; S2: The mixture was centrifuged at 3000 rpm for 5 minutes to separate into layers, obtaining drill cuttings residue in the lower layer and a liquid phase in the upper layer. The drill cuttings residue was air-dried and its oil content was measured; the liquid phase in the upper layer was collected; S3: Protonate the liquid phase by introducing carbon dioxide at a rate of 1.0 L / min for 60 min, separate the layers, recover the upper oil phase (petroleum-based substances), and remove the lower aqueous phase mixture; S4: nitrogen was introduced into the aqueous phase mixture at a flow rate of 1.0 L / min for 60 min for deprotonation treatment, the layers were separated, and the upper oil phase, i.e., the deoiling agent, was recovered.
[0055] The degreasing agent in this embodiment was prepared as follows: N,N-dimethylethanolamine and n-valeric acid were mixed in a molar ratio of 1:1.2, stirred and dissolved, and toluene and p-toluenesulfonic acid were added. The amount ratio of N,N-dimethylethanolamine to toluene was 0.1 mol:20 mL, and the mass of p-toluenesulfonic acid was 0.8% of the total mass of N,N-dimethylethanolamine and n-valeric acid. After reacting at 120° C. for 4 h, a degreasing agent was obtained.
[0056] Comparative Example 1 This comparative example provides a method for processing oil-based drill cuttings, comprising the following steps: S1: Mix oil-based drill cuttings and degreaser in a mass ratio of 1:2, stir at a speed of 500 r / min for 30 minutes, add water in an amount of 30% by mass of the degreaser, and continue stirring at a speed of 500 r / min for 100 minutes to obtain a mixture; S2: The mixture was centrifuged at 3000 rpm for 5 minutes to separate into layers, obtaining drill cuttings residue in the lower layer and a liquid phase in the upper layer. The drill cuttings residue was air-dried and its oil content was measured; the liquid phase in the upper layer was collected; S3: Protonate the liquid phase by introducing carbon dioxide at a rate of 1.0 L / min for 60 min, separate the layers, recover the upper oil phase (petroleum-based substances), and remove the lower aqueous phase mixture; S4: nitrogen was introduced into the aqueous phase mixture at a flow rate of 1.0 L / min for 60 min for deprotonation treatment, the layers were separated, and the upper oil phase, i.e., the deoiling agent, was recovered.
[0057] The degreasing agent in this embodiment is 2-(dimethylamino)ethyl pivalate, which is prepared as follows: Pivalic acid is added to a dry reaction flask, cooled to 0°C in an ice bath, and SOCl2 is slowly added dropwise (addition time is greater than 30 minutes) to obtain a reactant; the molar ratio of pivalic acid to SOCl2 is 1:1.5; DMF is added to the reactant (the ratio of pivalic acid to DMF is 100 g:1 drop), the ice bath is removed, the temperature is raised to reflux (70-80°C), and stirring is performed for approximately 2 hours until no gas escapes to obtain product I; product I is subjected to reduced pressure distillation, and the fraction at 105-107°C is collected to obtain pivaloyl chloride.
[0058] Under ice bath conditions, N,N-dimethylethanolamine, triethylamine, and anhydrous DCM are added to a reaction vessel with a temperature below 5°C to obtain a reaction mixture; pivaloyl chloride is dissolved in an equal volume of anhydrous DCM and slowly added dropwise to the reaction mixture (dropping time is greater than 30 min), maintaining the temperature below 5°C; after the dropwise addition is completed, the ice bath is removed, and the mixture is stirred at room temperature for 3 hours to obtain product II; product II is filtered to obtain a filtrate; the filtrate is washed with 5% mass concentration dilute hydrochloric acid, saturated NaHCO3 solution, and saturated brine, in sequence, and then dried over anhydrous MgSO4 for 30 minutes, and then DCM is removed by rotary evaporation to obtain 2-(dimethylamino)ethyl pivalate.
[0059] The molar ratio of pivaloyl chloride, N,N-dimethylethanolamine, and triethylamine is 1:1.1:1.2; the usage ratio of N,N-dimethylethanolamine to anhydrous DCM is 1 g:10 mL.
[0060] The oil-based drill cuttings, drill cutting residues, and degreaser recovery rates of the above-mentioned embodiments were tested using the following method: Oil content: The oil content of oil-based drill cuttings and drill cutting residues shall be tested in accordance with HJ 1051-2019 "Determination of Petroleum in Soil by Infrared Spectrophotometry"; Degreaser recovery rate: calculated by the mass ratio of recovered degreaser to added degreaser.
[0061] The test results are shown in Table 1.
[0062] Table 1
[0063] As can be seen from the data in Table 1, the methods for treating oil-based drill cuttings provided in various embodiments of the present invention all have good oil removal effects, and the deoiling agent recovery rate is high, and the deoiling agent has excellent cyclic stability; among them, tertiary amine ester compounds containing tertiary carbon groups have better stability than straight-chain tertiary amine esters; as can be seen from the comparative example data, increasing the amount of water added to the system will lead to increased hydrolysis of the deoiling agent and a sharp decrease in the recovery rate.
[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the technical solutions of the embodiments of the present invention.
Claims
1. A method for degreasing oil-based drill cuttings, characterized in that: The process includes the following steps: S1: After mixing the oil-based drill cuttings and the degreaser, water is added and the mixture is continuously stirred to obtain a mixture; S2: centrifuging the mixture and taking the upper liquid phase; S3: introducing CO2 into the liquid phase for protonation treatment, separating the layers, recovering the upper oil phase, and taking the lower aqueous phase mixture; S4: introducing N2 into the aqueous phase mixture for deprotonation, separating the layers, and recovering the degreasing agent; The degreasing agent includes tertiary amine ester compounds.
2. The oil-based drill cuttings degreasing method according to claim 1, characterized in that: The tertiary amine ester compound is a tertiary amine ester compound containing a tertiary carbon group.
3. The oil-based drill cuttings degreasing method according to claim 2, characterized in that: The tertiary amine ester compound containing a tertiary carbon group is 2-(dimethylamino)ethyl pivalate.
4. The oil-based drill cuttings degreasing method according to any one of claims 1 to 3, characterized in that: The mass ratio of the oil-based drill cuttings to the deoiling agent is 1:(1-3).
5. The oil-based drill cuttings degreasing method according to any one of claims 1 to 3, characterized in that: The amount of water added in step S1 does not exceed 20% of the mass of the degreasing agent.
6. The oil-based drill cuttings degreasing method according to any one of claims 1 to 3, characterized in that: The step of introducing CO2 into the liquid phase for protonation treatment comprises: introducing CO2 into the liquid phase at a flux of 0.5-1.5 L / min for protonation treatment.
7. The oil-based drill cuttings degreasing method according to any one of claims 1 to 3, characterized in that: The step of introducing N2 into the aqueous phase mixture for deprotonation treatment comprises: introducing N2 into the aqueous phase mixture at a flux of 0.5-1.5 L / min for deprotonation treatment.
8. The oil-based drill cuttings degreasing method according to any one of claims 1 to 3, characterized in that: The degreasing agent also includes a stabilizer.
9. The oil-based drill cuttings degreasing method according to claim 8, characterized in that: The stabilizer is saponin.
10. The oil-based drill cuttings deoiling method according to claim 9, characterized in that: The mass ratio of the tertiary amine ester compound to the stabilizer in the degreasing agent is 10:(2-5).