An oil displacement agent and an oil displacement method

Abstract

The present invention provides a flooding agent and a flooding method. The flooding agent includes an emulsifier, and the emulsifier includes sodium oleate, glucoside and betaine.

Description

Technical Field

[0001] The present invention relates to an oil displacement agent, and particularly to an oil displacement method. Background Art

[0002] The content and composition of solid hydrocarbons, asphaltenes and resins in heavy oil are important factors affecting rheology; high resin and asphaltene contents also result in high viscosity, high density and poor rheology of heavy oil. Therefore, reducing the viscosity of heavy oil and improving its fluidity are the main problems in heavy oil exploitation and gathering and transportation.

[0003] The key to heavy oil development is to improve the fluidity of crude oil in the formation. The most effective method is to heat to reduce the viscosity of crude oil. However, due to large investment and high cost of thermal recovery and some reservoir conditions, not all heavy oils are suitable for thermal recovery.

[0004] Injecting gas or injecting chemical agents to form emulsions is also a method to improve the fluidity of crude oil in the reservoir. However, the heavy oil recovery rate needs to be improved. Summary of the Invention

[0005] One aspect of the present invention provides an oil displacement agent, which includes an emulsifier, and the emulsifier includes sodium oleate, glucoside and betaine.

[0006] In a specific embodiment, the glucoside is coconut glucoside and / or lauryl glucoside.

[0007] In a specific embodiment, the betaine is coconut amide propyl hydroxysulfobetaine and / or lauryl amide propyl betaine.

[0008] In a specific embodiment, the mass ratio of sodium oleate, glucoside and betaine is 1:(0.5 - 4):(1 - 5).

[0009] In a specific embodiment, the oil displacement agent further includes water. Based on the total mass of the oil displacement agent being 100%, the content of the emulsifier is 0.2% to 0.25%.

[0010] In a specific embodiment, the oil displacement agent further includes a dispersant and / or an emulsion stabilizer.

[0011] In a specific embodiment, the dispersant is sodium humate and / or sodium lignosulfonate.

[0012] In a specific embodiment, the mass ratio of sodium humate and sodium lignosulfonate is 1:1.

[0013] In a specific embodiment, the emulsion stabilizer is sodium carbonate and / or sodium bicarbonate.

[0014] In a specific embodiment, based on the total mass of the oil displacement agent being 100%, the content of the dispersant is 0.25% to 0.5%.

[0015] In a specific embodiment, the content of the emulsification stabilizer is 0.025% to 0.1%.

[0016] The second aspect of the present invention provides an oil displacement method, which includes the following steps:

[0017] 1) Displace with the oil displacement agent according to any one of the first aspect of the present invention.

[0018] In a specific embodiment, it further includes step 2) gas displacement.

[0019] In a specific embodiment, the gas displacement is carbon dioxide displacement.

[0020] In a specific embodiment, the total volume of the oil displacement agent displacement is 0.05 PV to 0.8 PV.

[0021] In a specific embodiment, the total volume of the gas displacement is 0.1 PV to 2 PV.

[0022] In a specific embodiment, the total volume of the oil displacement agent displacement is 0.5 PV, and the total volume of the gas displacement is 0.75 to 1 PV.

[0023] In a specific embodiment, steps 1) and 2) are alternated 5 to 15 rounds.

[0024] Advantages of the present invention:

[0025] 1) According to the instability coefficient of the oil displacement agent, it can be known that there can be a synergistic effect among the components sodium oleate, glucoside, and betaine in the oil displacement agent of the present invention, so that a stable emulsion can be formed by emulsifying with crude oil.

[0026] 2) According to the oil recovery rate obtained by alternately injecting the oil displacement agent and carbon dioxide, it can be known that the combined use of the oil displacement agent displacement and gas displacement of the present invention produces a synergistic effect, thereby greatly improving the oil recovery rate. Specific embodiments

[0027] The present invention will be further described below in conjunction with embodiments, but the embodiments of the present invention are only exemplary descriptions, and this implementation manner does not constitute a limitation to the present invention under any circumstances.

[0028] (1) Emulsification performance evaluation method

[0029] The more stable the emulsion formed by the oil displacement agent and crude oil, the better the interaction between the oil displacement agent and crude oil, and the more conducive to displacing crude oil. The oil displacement agent is distinguished by the stability of the formed emulsion.

[0030] Evaluation method: Take a 10 mL graduated test tube with a stopper, accurately add 5 mL of the crude oil for the experiment, and then accurately pipette 5 mL of the oil displacement agent with a pipette. Cover the stopper, place the test tube on a test tube rack in a 50 °C water bath and keep it at a constant temperature for 15 min, and shake it 100 times; Immediately place the shaken test tube vertically on the test tube rack, start timing at the same time, and observe and record the height of the oil-water interface every 5 min with the help of a spotlight for a total of one hour. Then use the dilution method and the filter paper method to judge the type of emulsion respectively. If it is water-in-oil type, adjust the formula; if it is oil-in-water type, measure the instability coefficient of the emulsion. The stability of the emulsion is expressed by the instability coefficient (USI). The instability coefficient is defined as follows:

[0031]

[0032] In the formula: USI - instability coefficient, mL;

[0033] V(t) - the volume of water separated at time t, calculated based on the height of the oil-water interface, mL;

[0034] t - test time, min.

[0035] According to the definition, the smaller the instability coefficient, the better the stability of the emulsion.

[0036] (2) Oil displacement recovery factor after indoor simulated water flooding

[0037] The simulated oil displacement experimental device used includes an injection pump, an intermediate container, a core holder, and a produced fluid collection device. During the experiment, the crude oil, reservoir water, oil displacement agent, and carbon dioxide are respectively filled into four different intermediate containers. The core is placed in the core holder with a permeability of 1400 millidarcies, a length of 30 cm, and a diameter of 2.54 cm. The core is evacuated and saturated with water, and the porosity of the core is calculated according to the saturated water volume. Then the water in the core is displaced with the crude oil, that is, saturated with oil, and the saturated oil volume V 饱和油 is calculated according to the displaced water volume. Then, displacement is carried out based on the experimental design to obtain the produced fluid, and the crude oil is separated from the produced fluid. The amount of separated crude oil is represented by V 采油量 . The recovery factor is calculated according to formula (1).

[0038] Recovery factor = V 采油量 / V 饱和油 *100% Formula (1).

[0039] Example 1

[0040] 1) Weigh the dispersant sodium humate, the dispersant sodium lignosulfonate, and the emulsification stabilizer sodium carbonate, and dissolve them in the reservoir water with a salinity of 8000 mg / L (the salts in it are composed of sodium chloride, calcium chloride, and magnesium chloride, and the calcium and magnesium ions are 120 mg / L) to obtain the first solution;

[0041] 2) Weigh sodium oleate emulsifier, coconut oil glucoside emulsifier and coconut oil amide propyl hydroxysulfobetaine emulsifier, dissolve them in the first solution to obtain an oil displacement agent. Among them, the content of sodium oleate emulsifier in the oil displacement agent is 0.1 wt%, the content of coconut oil glucoside emulsifier in the oil displacement agent is 0.05 wt%, the content of coconut oil amide propyl hydroxysulfobetaine emulsifier in the oil displacement agent is 0.1 wt%, the content of humic acid sodium dispersant in the oil displacement agent is 0.25 wt%, the content of sodium lignosulfonate dispersant in the oil displacement agent is 0.25 wt%, and the content of sodium carbonate emulsification stabilizer in the oil displacement agent is 0.1 wt%.

[0042] The viscosity of the experimental crude oil used for measuring the instability coefficient of the emulsion at 50 °C is 1000 mPa·s, and the measured instability coefficient is 0.25 mL.

[0043] Example 2

[0044] The operation of preparing the oil displacement agent is the same as that in Example 1.

[0045] Among them, the content of sodium oleate emulsifier in the oil displacement agent is 0.1 wt%, the content of coconut oil glucoside emulsifier in the oil displacement agent is 0.05 wt%, the content of coconut oil amide propyl hydroxysulfobetaine emulsifier in the oil displacement agent is 0.1 wt%, the content of humic acid sodium dispersant in the oil displacement agent is 0.25 wt%, the content of sodium lignosulfonate dispersant in the oil displacement agent is 0.25 wt%, and no emulsification stabilizer is contained.

[0046] The viscosity of the experimental crude oil used for measuring the instability coefficient of the emulsion at 50 °C is 1000 mPa·s, and the measured instability coefficient is 0.85 mL.

[0047] Example 3

[0048] The operation of preparing the oil displacement agent is the same as that in Example 1.

[0049] Among them, the content of sodium oleate emulsifier in the oil displacement agent is 0.1 wt%, the content of coconut oil glucoside emulsifier in the oil displacement agent is 0.05 wt%, the content of coconut oil amide propyl hydroxysulfobetaine emulsifier in the oil displacement agent is 0.1 wt%, the content of humic acid sodium dispersant in the oil displacement agent is 0.25 wt%, no dispersant and emulsification stabilizer are contained.

[0050] The viscosity of the experimental crude oil used for measuring the instability coefficient of the emulsion at 50 °C is 1000 mPa·s, and the measured instability coefficient is 1.25 mL.

[0051] Example 4

[0052] 1) weighing dispersant sodium humate, dispersant sodium lignin sulfonate, emulsion stabilizer sodium carbonate and emulsion stabilizer sodium bicarbonate, and dissolving them in reservoir water with a mineralization of 12000 mg / L (the salts consist of sodium chloride, calcium chloride and magnesium chloride, wherein the calcium and magnesium ions are 350 mg / L) to obtain a first solution;

[0053] 2) Weighing emulsifier sodium oleate, emulsifier lauryl glucoside and emulsifier lauramide propyl betaine, dissolving them in the first solution to obtain an oil-displacing agent, wherein the content of emulsifier sodium oleate in the oil-displacing agent is 0.02wt%, the content of emulsifier lauryl glucoside in the oil-displacing agent is 0.08wt%, the content of emulsifier lauramide propyl betaine in the oil-displacing agent is 0.1wt%, the content of dispersant sodium humate in the oil-displacing agent is 0.15wt%, the content of dispersant sodium lignin sulfonate in the oil-displacing agent is 0.15wt%, the content of emulsifier sodium carbonate in the oil-displacing agent is 0.025wt%, and the content of emulsifier sodium bicarbonate in the oil-displacing agent is 0.025wt%.

[0054] The viscosity of the experimental crude oil used to determine the instability coefficient of the emulsion at a temperature of 50°C is 500mPa.s, and the measured instability coefficient is 0.3mL.

[0055] Comparative Example 1

[0056] Weigh the emulsifier sodium oleate and dissolve it in 8000 mg / L reservoir water (the salts are composed of sodium chloride, calcium chloride, and magnesium chloride, and the calcium and magnesium ions are 120 mg / L) to obtain an oil displacement agent. The content of the emulsifier sodium oleate in the oil displacement agent is 0.25 wt%, and no dispersant and emulsion stabilizer are contained.

[0057] The viscosity of the experimental crude oil used to determine the instability coefficient of the emulsion at a temperature of 50°C was 1000mPa.s, and the measured instability coefficient was 4.25mL.

[0058] Comparative Example 2

[0059] Weigh the emulsifier coconut glucoside and dissolve it in 8000 mg / L reservoir water (wherein the salt consists of sodium chloride, calcium chloride, and magnesium chloride, wherein the calcium and magnesium ions are 120 mg / L) to obtain an oil displacement agent. The content of the emulsifier coconut glucoside in the oil displacement agent is 0.25 wt %, and no dispersant and emulsion stabilizer are contained.

[0060] The viscosity of the experimental crude oil used to determine the instability coefficient of the emulsion at a temperature of 50°C was 1000mPa.s, and the measured instability coefficient was 3.6mL.

[0061] Comparative Example 3

[0062] Weigh oleamide propyl hydroxysulfobetaine emulsifier and dissolve it in reservoir water with a salinity of 8000 mg / L (the salts in it are composed of sodium chloride, calcium chloride, and magnesium chloride, and the calcium and magnesium ions are 120 mg / L) to obtain an oil displacement agent. Among them, the content of oleamide propyl hydroxysulfobetaine emulsifier in the oil displacement agent is 0.25 wt%, and no dispersant and emulsion stabilizer are contained.

[0063] When measuring the instability coefficient of the emulsion, the viscosity of the experimental crude oil at 50 °C is 1000 mPa·s, and the measured instability coefficient is 2.8 mL.

[0064] Example 6

[0065] Indoor simulated oil displacement experiment:

[0066] The viscosity of the crude oil at 50 °C is 1000 mPa·s.

[0067] The salinity of the reservoir water is 8000 mg / L, and the calcium and magnesium ions are 120 mg / L.

[0068] Water drive the reservoir with reservoir water for 2 PV (simulating the reservoir conditions after water drive), and the recovery rate is 46.2%. Then inject 0.5 PV of the oil displacement agent prepared in Example 1, and then water drive with reservoir water for 1.5 PV.

[0069] The final enhanced oil recovery is 7.5%.

[0070] Example 7

[0071] Indoor simulated oil displacement experiment:

[0072] The viscosity of the crude oil at 50 °C is 500 mPa·s.

[0073] The salinity of the reservoir water is 12000 mg / L, and the calcium and magnesium ions are 350 mg / L.

[0074] Water drive the reservoir with reservoir water for 2 PV (simulating the reservoir conditions after water drive), and the recovery rate is 45.8%. First, inject 0.5 PV of the oil displacement agent prepared in Example 4, and then inject 1.5 PV of water.

[0075] The enhanced oil recovery is 7.8%.

[0076] Example 8

[0077] Indoor simulated oil displacement experiment:

[0078] The viscosity of the crude oil at 50 °C is 1000 mPa·s.

[0079] The salinity of the reservoir water is 8000 mg / L, and the calcium and magnesium ions are 120 mg / L.

[0080] Using reservoir water for water flooding of 2 PV (simulating reservoir conditions after water flooding), the oil recovery rate is 45.3%. Subsequently, 0.1 PV of the oil displacement agent prepared in Example 1 is injected in sequence, and then 0.2 PV of carbon dioxide is injected. A total of 5 cycles of alternation are carried out, where the total injection volume of the oil displacement agent is 0.5 PV and the total injection volume of carbon dioxide is 1.0 PV.

[0081] Finally, the oil recovery rate is increased by 13.8%.

[0082] Example 9

[0083] Indoor simulated oil displacement experiment:

[0084] The viscosity of the crude oil at 50 °C is 500 mPa·s.

[0085] The salinity of the reservoir water is 12000 mg / L, among which the calcium and magnesium ions are 350 mg / L.

[0086] Using reservoir water for water flooding of 2 PV (simulating reservoir conditions after water flooding), the oil recovery rate is 46.1%. First, 0.1 PV of the oil displacement agent prepared in Example 4 is injected, and then 0.15 PV of carbon dioxide is injected. 5 cycles of alternation are carried out, where the total injection volume of the oil displacement agent is 0.5 PV and the total injection volume of carbon dioxide is 0.75 PV.

[0087] The oil recovery rate is increased by 14.5%.

[0088] Comparative Example 4

[0089] Indoor simulated oil displacement experiment:

[0090] The viscosity of the crude oil at 50 °C is 1000 mPa·s.

[0091] The salinity of the reservoir water is 8000 mg / L, among which the calcium and magnesium ions are 120 mg / L.

[0092] Using reservoir water for water flooding of 2 PV (simulating reservoir conditions after water flooding), the oil recovery rate is 47.2%. Continue to use reservoir water for water flooding of 2 PV.

[0093] The oil recovery rate is increased by 5.2%.

[0094] Comparative Example 5

[0095] Indoor simulated oil displacement experiment:

[0096] The viscosity of the crude oil at 50 °C is 500 mPa·s.

[0097] The salinity of the reservoir water is 12000 mg / L, among which the calcium and magnesium ions are 350 mg / L.

[0098] Using reservoir water for water flooding of 2 PV (simulating reservoir conditions after water flooding), the oil recovery rate is 45.6%. Inject 0.75 PV of carbon dioxide, and then carry out water flooding of 1.25 PV.

[0099] The oil recovery rate is increased by 4.1%.

[0100] From the comparison of the oil recovery rates increased by Examples 6 to 9 with those increased by Comparative Examples 4 and 5, it can be seen that the use of the oil displacement agent of the present invention can significantly increase the oil recovery rate; further, by comprehensively comparing Example 9 with Examples 7 and Comparative Example 5, it can be seen that when the oil displacement agent of the present invention is used in combination with carbon dioxide, the increased oil recovery rate (14.5% in Example 9) is significantly higher than the sum of the oil displacement agent used alone (7.8% in Example 7) and carbon dioxide used alone (4.1% in Comparative Example 5). Obviously, the combined use of the two produces a synergistic effect.

[0101] Although the present invention has been described with reference to specific embodiments, those skilled in the art should understand that various changes can be made without departing from the true spirit and scope of the present invention. In addition, various changes can be made to the subject matter, spirit and scope of the present invention to adapt to specific situations, materials, material compositions and methods. All such changes are included within the scope of the claims of the present invention.

Claims

1. An oil displacement agent, which comprises an emulsifier, and the emulsifier comprises sodium oleate, glucoside and betaine; Among them, The mass ratio of sodium oleate, glucoside and betaine is 1:(0.5 - 4):(1 - 5); The glucoside is coconut glucoside and / or lauryl glucoside; The betaine is coconut amide propyl hydroxysulfobetaine and / or lauryl amide propyl betaine.

2. The oil displacement agent according to claim 1, wherein, The oil displacement agent further comprises water. Calculated based on the total mass of the oil displacement agent as 100%, the content of the emulsifier is 0.2% to 0.25%.

3. The oil displacement agent according to claim 1 or 2, characterized in that, The oil displacement agent further comprises a dispersant and / or an emulsion stabilizer.

4. The oil displacement agent according to claim 3, wherein The dispersant is sodium humate and / or sodium lignosulfonate.

5. The oil displacement agent according to claim 4, characterized in that, The mass ratio of sodium humate and sodium lignosulfonate is 1:

1.

6. The oil displacement agent according to claim 3, characterized in that, The emulsion stabilizer is sodium carbonate and / or sodium bicarbonate.

7. The oil displacement agent according to claim 3, wherein Calculated based on the total mass of the oil displacement agent as 100%, the content of the dispersant is 0.25% to 0.5%; and / or The content of the emulsion stabilizer is 0.025% to 0.1%.

8. An oil displacement method, which comprises the following steps: 1) Displace with the oil displacement agent according to any one of claims 1 to 7.

9. The oil displacement method according to claim 8, characterized in that, The oil displacement method further comprises step 2) gas displacement.

10. The oil displacement method according to claim 9, wherein, The gas displacement is carbon dioxide displacement.

11. The oil displacement method according to claim 9, wherein The total volume of the oil displacement agent displacement is 0.05PV to 0.8PV; and / or The total volume of the gas displacement is 0.1PV to 2PV.

12. The oil displacement method according to claim 11, wherein, The total volume of the oil displacement agent displacement is 0.5PV, and the total volume of the gas displacement is 0.75 to 1PV.

13. The oil displacement method according to claim 9, characterized in that, Steps 1) and 2) are alternated 5 to 15 rounds.

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