An oil reservoir cleaning agent and a method of preparing the same

Abstract

The application belongs to the technical field of cleaning agents, and particularly relates to an oil layer cleaning agent and a preparation method thereof. The oil layer cleaning agent is composed of the following raw materials in percentage by weight: polyammonia ether sulfate 0.3-0.5%, sodium dodecyl benzene sulfonate 0.1-0.3%, tripropylene glycol 6-10%, and the rest is water. The structural formula of the polyammonia ether sulfate is as follows: wherein m=5-20, and n=5-50. The oil layer cleaning agent has the advantages of good crude oil cleaning effect, the highest oil washing rate of 98.8%, simple preparation, and no by-products.

Description

Technical Field

[0001] This invention belongs to the field of cleaning agent technology, specifically relating to an oil layer cleaning agent and its preparation method. Background Technology

[0002] Some oil resources remain trapped in reservoirs, becoming residual oil that is difficult to extract. This residual oil exists mainly in three forms: oil films or oil spots adsorbed on the pore walls of rocks, oil droplets trapped in throats due to capillary forces, and "dead oil zones" that cannot be reached by displacement water due to macroscopic and microscopic heterogeneity. How to effectively "wash" out this residual oil that is firmly attached to the rock surface is a key challenge in improving oilfield recovery. The principle is similar to applying a "detergent" to the formation to remove oil stains.

[0003] Currently, commonly used oil reservoir cleaning agents mainly consist of alkali agents, single surfactants, and conventional acids. Alkaline systems easily cause formation clay swelling and rock skeleton damage, and tend to form high-viscosity emulsions with crude oil, increasing the difficulty of flowback. Single surfactants have poor temperature and salt resistance and are easily deactivated under high salinity and high temperature formation conditions, resulting in insufficient cleaning effect on stubborn oil films. Although strong acid cleaning agents have strong scale-dissolving capabilities, they are highly corrosive to tubing and formation rocks, posing high construction risks, and some agents have poor biodegradability, presenting environmental safety hazards.

[0004] Existing composite reservoir cleaning agents generally suffer from poor compatibility, easy failure at high temperatures, and easy secondary adsorption and deposition of oil stains after cleaning, making it difficult to simultaneously achieve the goals of efficient oil removal, low damage to the reservoir, and environmental friendliness. For complex reservoirs with high wax content, high asphaltene content, and low permeability, there is still a lack of a dedicated cleaning agent that is highly efficient, has good compatibility, causes minimal damage to the formation and tubing, and is environmentally safe. Therefore, developing a novel reservoir cleaning agent with excellent performance and broad applicability, along with its preparation method, is of significant practical importance for improving oilfield unblocking effects, extending production cycles, and enhancing oil recovery rates. Summary of the Invention

[0005] This invention addresses the shortcomings of existing technologies by providing an oil reservoir cleaning agent and its preparation method. The oil reservoir cleaning agent of this invention has the advantages of good crude oil cleaning effect, simple preparation, and no by-products.

[0006] The first objective of this invention discloses an oil layer cleaning agent, which, by weight percentage, is composed of the following raw materials: Polyurethane sulfate 0.3-0.5%; Sodium dodecylbenzenesulfonate 0.1-0.3%; Tripropylene glycol 6-10%; Water balance; The structural formula of the polyurethane sulfate is as follows:

[0007] Where m = 5 - 20, n = 5 - 50.

[0008] The second objective of this invention is to provide a method for preparing the aforementioned oil layer cleaning agent, the method specifically comprising the following steps: (1) In a high-pressure reactor, add 3,5-diaminotrifluorotoluene and catalyst, purge the pipeline and reactor with nitrogen, evacuate, heat to 80-90℃, stop evacuating, add propylene oxide, continue stirring and heat to 110-160℃, then gradually reduce the pressure, and when the pressure no longer decreases, cool the reaction system to 80-90℃. (2) Slowly introduce ethylene oxide. After the introduction is complete, raise the temperature to 120-170℃. Then, gradually reduce the pressure. When the pressure no longer decreases, cool the reaction system to room temperature and neutralize the pH to 7-8 with phosphoric acid. (3) Add aminosulfonic acid powder, heat to 110-130℃, keep the reaction at this temperature for 60-120 min, cool to 40℃ or below, add 10wt% ethanolamine solution, adjust pH to 7-8, and obtain polyurethane sulfate. (4) Water, polyurethane sulfate, sodium dodecylbenzene sulfonate and tripropylene glycol are added to the reactor in sequence and stirred evenly to obtain oil layer cleaning agent.

[0009] In this invention, preferably, the molar ratio of propylene oxide, ethylene oxide, aminosulfonic acid and 3,5-diaminotrifluorotoluene is 10-40:10-100:0.8-1.2:1.

[0010] Preferably, the catalyst in step (1) is one of sodium hydroxide, potassium hydroxide, and potassium carbonate, with a mass ratio of 0.01-0.015:1 to 3,5-diaminotrifluorotoluene.

[0011] The oil layer cleaning agent of this invention is a composite cleaning agent. Polyurethane sulfate is a nonionic and anionic composite surfactant with good interfacial activity. Its fluorocarbon groups open channels with ultra-low tension, penetrating micropores. Long-chain sulfate groups can insert into highly viscous organic matter such as waxes, asphaltenes, and gums, peeling them off the rock surface. It has wetting, dispersing, and solubilizing effects, promoting better dissolution of waxes and other substances in the cleaning agent. The long-chain polyether can firmly encapsulate the peeled oil droplets, forming a stable emulsion and preventing the back-adhesion of highly viscous crude oil. Sodium dodecylbenzenesulfonate is an anionic surfactant that can disrupt intermolecular forces and weaken intermolecular interactions, allowing highly viscous organic matter such as waxes, asphaltenes, and gums to be better dispersed in the composite cleaning agent. Tripropylene glycol has a small molecular weight, therefore, strong penetrating power and good cleaning effect on the boundary layer. It also has a good dissolving effect on highly viscous crude oil, reducing its viscosity. Furthermore, its interaction with other raw materials allows for deep, rapid, and thorough cleaning of highly viscous crude oil.

[0012] The beneficial effects and advantages of this invention compared with the prior art are as follows: (1) The oil layer cleaning agent of the present invention produces no by-products during the production process, which is a green production process; (2) The oil layer cleaning agent of the present invention has a high oil washing rate, which can reach up to 98.8%. Detailed Implementation

[0013] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0014] The technical solution of the present invention will be further described below with reference to specific embodiments: Example 1 (1) In a high-pressure reactor, 0.1 mol of 3,5-diaminotrifluorotoluene and 0.176 g of sodium hydroxide were added. The pipeline and reactor were purged with nitrogen gas, a vacuum was drawn, and the temperature was raised to 80°C. The vacuum was stopped, 1 mol of propylene oxide was added, and stirring was continued and the temperature was raised to 110°C. After that, the pressure gradually decreased. When the pressure no longer decreased, the reaction system was cooled to 80°C. (2) Slowly introduce 1 mol of ethylene oxide. After the introduction is complete, raise the temperature to 120°C. Then, gradually reduce the pressure. When the pressure no longer decreases, cool the reaction system to room temperature and neutralize the pH to 7-8 with phosphoric acid. (3) Add 0.08 mol aminosulfonic acid powder, heat to 110℃, keep warm for 60 min, cool to 40℃, add 10 wt% ethanolamine solution, adjust pH to 7-8, and obtain polyurethane sulfate.

[0015] Example 2 (1) In a high-pressure reactor, 0.1 mol of 3,5-diaminotrifluorotoluene and 0.213 g of potassium carbonate were added. The pipeline and reactor were purged with nitrogen gas, a vacuum was drawn, and the temperature was raised to 80°C. The vacuum was stopped, 2 mol of propylene oxide was added, and stirring was continued and the temperature was raised to 120°C. After that, the pressure gradually decreased. When the pressure no longer decreased, the reaction system was cooled to 80°C. (2) Slowly introduce 4 mol of ethylene oxide. After the introduction is complete, raise the temperature to 140°C. Then, gradually reduce the pressure. When the pressure no longer decreases, cool the reaction system to room temperature and neutralize the pH to 7-8 with phosphoric acid. (3) Add 0.12 mol aminosulfonic acid powder, heat to 120℃, keep warm for 120 min, cool to 35℃, add 10 wt% ethanolamine solution, adjust pH to 7-8, and obtain polyurethane sulfate.

[0016] Example 3 (1) In a high-pressure reactor, 0.1 mol of 3,5-diaminotrifluorotoluene and 0.24 g of potassium hydroxide were added. The pipeline and reactor were purged with nitrogen gas, a vacuum was drawn, and the temperature was raised to 85°C. The vacuum was stopped, 3 mol of propylene oxide was added, and stirring was continued and the temperature was raised to 140°C. After that, the pressure gradually decreased. When the pressure no longer decreased, the reaction system was cooled to 90°C. (2) Slowly introduce 4 mol of ethylene oxide. After the introduction is complete, raise the temperature to 150°C. Then, gradually reduce the pressure. When the pressure no longer decreases, cool the reaction system to room temperature and neutralize the pH to 7-8 with phosphoric acid. (3) Add 0.09 mol aminosulfonic acid powder, heat to 125℃, keep warm for 60 min, cool to 30℃, add 10 wt% ethanolamine solution, adjust pH to 7-8, and obtain polyurethane sulfate.

[0017] Example 4 (1) In a high-pressure reactor, 0.1 mol of 3,5-diaminotrifluorotoluene and 0.25 g of sodium hydroxide were added. The pipeline and reactor were purged with nitrogen gas, a vacuum was drawn, and the temperature was raised to 85°C. The vacuum was stopped, 4 mol of propylene oxide was added, and stirring was continued and the temperature was raised to 160°C. After that, the pressure gradually decreased. When the pressure no longer decreased, the reaction system was cooled to 80°C. (2) Slowly introduce 6 mol of ethylene oxide. After the introduction is complete, raise the temperature to 160°C. Then, gradually reduce the pressure. When the pressure no longer decreases, cool the reaction system to room temperature and neutralize the pH to 7-8 with phosphoric acid. (3) Add 0.11 mol aminosulfonic acid powder, heat to 130℃, keep warm for 90 min, cool to 30℃, add 10 wt% ethanolamine solution, adjust pH to 7-8, and obtain polyurethane sulfate.

[0018] Example 5 (1) In a high-pressure reactor, 0.1 mol of 3,5-diaminotrifluorotoluene and 0.264 g of sodium hydroxide were added. The pipeline and reactor were purged with nitrogen gas, a vacuum was drawn, and the temperature was raised to 90°C. The vacuum was stopped, 3 mol of propylene oxide was added, and stirring was continued and the temperature was raised to 150°C. After that, the pressure gradually decreased. When the pressure no longer decreased, the reaction system was cooled to 85°C. (2) Slowly introduce 10 mol of ethylene oxide. After the introduction is complete, raise the temperature to 170°C. Then, gradually reduce the pressure. When the pressure no longer decreases, cool the reaction system to room temperature and neutralize the pH to 7-8 with phosphoric acid. (3) Add 0.1 mol of aminosulfonic acid powder, heat to 125°C, keep warm for 90 min, cool to 30°C, add 10 wt% ethanolamine solution, adjust pH to 7-8, and obtain polyurethane sulfate.

[0019] Examples 6-10, Comparative Examples 1-3 Water, polyurethane sulfate, sodium dodecylbenzene sulfonate, and tripropylene glycol were added sequentially to the reactor and stirred until homogeneous to obtain an oil layer cleaning agent.

[0020] The dosage of each component is shown in Table 1.

[0021] Table 1. Composition of Examples 6-10 and Comparative Examples 1-3 Test Example 1: Oil Washing Efficiency Test The oil washing efficiency was tested using the method described below, and the test results are shown in Table 2.

[0022] (1) Take the oil mud and sand scattered around a certain oil well, place it in an 80℃ oven, and let it stand for 7 days to age.

[0023] (2) Take 5g of aged oily mud sand and put it into a 100ml Erlenmeyer flask. Add 50g of the cleaning agent of this invention, mix thoroughly, place in an 80℃ oven, and let stand for 48h.

[0024] (3) Use clean cotton gauze to remove the crude oil floating in the sample solution and the crude oil adhering to the bottle wall after it has been allowed to stand. Pour out the sample solution and rinse the oil sand 2 to 3 times with distilled water until there is no foam. Carefully pour out the solution. Place the conical flask in a constant temperature oven at 105℃ and dry it to constant weight. Weigh it.

[0025] (4) Use petroleum ether to wash the oil sand dried in step 3 until the petroleum ether is colorless. Place the conical flask with all the crude oil washed out in a 120°C oven and dry for 2 hours before weighing.

[0026] (5) Calculate the washing efficiency η × 100% Where η is the oil washing efficiency; m is the mass of the aged oil sand, in grams; m1 is the mass of the conical flask, in grams; m2 is the total mass of the conical flask and oil sand after washing, in grams; m3 is the total mass of the conical flask and the washed formation sand, in grams.

[0027] Table 2 Results of the wash-oil ratio test

[0028] As can be seen from Table 2: The difference between Example 6 and Comparative Example 1 is that Comparative Example 1 did not add tripropylene glycol, and the wash oil rate decreased by 8.6%.

[0029] The difference between Example 8 and Comparative Example 2 is that Comparative Example 2 did not add sodium dodecylbenzenesulfonate, and the wash oil rate decreased by 7.6%.

[0030] The difference between Example 10 and Comparative Example 3 is that Comparative Example 3 did not contain polyurethane sulfate, and the wash oil rate decreased by 9.2%.

[0031] Therefore, the polyurethane sulfate, sodium dodecylbenzene sulfonate, and tripropylene glycol components in this invention all contribute to improving the wash oil yield.

[0032] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

Claims

1. An oil layer cleaning agent, characterized in that, The oil layer cleaning agent, by weight percentage, is composed of the following raw materials: Polyurethane sulfate 0.3-0.5%; Sodium dodecylbenzenesulfonate 0.1-0.3%; Tripropylene glycol 6-10%; Water balance; The structural formula of the polyurethane sulfate is as follows: ， Where m = 5 - 20, n = 5 - 50.

2. The method for preparing the oil layer cleaning agent according to claim 1, characterized in that, The preparation method specifically includes the following steps: (1) In a high-pressure reactor, add 3,5-diaminotrifluorotoluene and catalyst, purge the pipeline and reactor with nitrogen, evacuate, heat to 80-90℃, stop evacuating, add propylene oxide, continue stirring and heat to 110-160℃, then gradually reduce the pressure, and when the pressure no longer decreases, cool the reaction system to 80-90℃. (2) Slowly introduce ethylene oxide. After the introduction is complete, raise the temperature to 120-170℃. Then, gradually reduce the pressure. When the pressure no longer decreases, cool the reaction system to room temperature and neutralize the pH to 7-8 with phosphoric acid. (3) Add aminosulfonic acid powder, heat to 110-130℃, keep the reaction at this temperature for 60-120 min, cool to 40℃ or below, add 10wt% ethanolamine solution, adjust pH to 7-8, and obtain polyurethane sulfate. (4) Water, polyurethane sulfate, sodium dodecylbenzene sulfonate and tripropylene glycol are added to the reactor in sequence and stirred evenly to obtain oil layer cleaning agent.

3. The method for preparing the oil layer cleaning agent according to claim 2, characterized in that, The molar ratio of propylene oxide, ethylene oxide, aminosulfonic acid and 3,5-diaminotrifluorotoluene is 10-40:10-100:0.8-1.2:

1.

4. The method for preparing the oil layer cleaning agent according to claim 2, characterized in that, The catalyst mentioned in step (1) is one of sodium hydroxide, potassium hydroxide, and potassium carbonate, with a mass ratio of 0.01-0.015:1 to 3,5-diaminotrifluorotoluene.

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