An oil production engineering displacement emulsion preparation method and its application

Abstract

The present invention discloses a preparation method and application of an oil production engineering displacement emulsion. The oil production engineering displacement emulsion is compounded from an anionic-nonionic surfactant, a cationic surfactant, a surfactant compound synergist, an organic phase, an organic base agent, a complexing agent, an emulsifier, and an organic chlorine remover. It solves the problems of poor interfacial, wetting, and salinity tolerance properties of conventional surfactant emulsions in tertiary oil recovery.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil production engineering, and particularly relates to a method for preparing a displacement emulsion for oil production engineering and its application. Background Art

[0002] The overall recovery rate of most original oil reservoirs in oil fields is only about 40%. Moreover, with the continuous increase in exploration and development efforts, more and more low-permeability and extra-low-permeability oil reservoirs have been discovered, but the exploitation difficulty is great. How to make good use of the remaining crude oil in low-permeability and extra-low-permeability oil reservoirs has become an important factor related to the continuous rapid development of the economy. The tertiary oil recovery technology is one of the most effective means to improve oil recovery. For low-permeability and extra-low-permeability oil reservoirs, using surfactant emulsions can increase the oil recovery by reducing the oil-water interfacial tension and changing the wettability.

[0003] The interfacial tension between oil and water and the wettability of oil reservoir rocks, as two important parameters involved in the oil displacement process, play a key role in the distribution, flow and exploitation degree of crude oil underground. Conventional ionic and non-ionic surfactants have the ability to reduce the interfacial tension, reduce the capillary pressure of oil droplets at the throat, reduce the movement resistance of oil droplets, change the wettability of the rock surface, and at the same time can also improve the seepage ability of the mixed fluid and improve the oil displacement efficiency.

[0004] Changing the viscous force and capillary force has an impact on the residual oil saturation of water-wet rocks. Increasing the displacement velocity and / or viscosity of the displacing phase can change the viscous force. Reducing the interfacial tension can change the capillary force. Under normal water flooding conditions, the residual oil saturation in the core is generally high. Reducing the interfacial tension can also significantly reduce the residual oil saturation.

[0005] Liu Jianying et al. optimized the corresponding composite oil displacement agent in the "Pilot Study on Surfactant Flooding in Ansai Low-Permeability Oil Reservoir" in 2001. This oil displacement agent has a strong ability to reduce the interfacial tension and strong emulsifying activity at the same time.

[0006] Yang Jian et al. stated in the "Preparation and Application Research of High-Effective Oil Displacement Surfactants" in 2018 that in the emulsification system of the surfactant compounding system, the oil / water interfacial tension can be reduced to 1.9×10 －3 mN / m, and the final oil displacement efficiency reaches 52.5%.

[0007] Fan Huabo et al. synthesized an anionic-nonionic surfactant AN211 with alkyl alcohol polyoxyethylene ether and maleic anhydride as raw materials in the "Preparation and Performance Evaluation of Anionic-Nonionic Surfactants for Improving Imbibition Efficiency" in 2019. Its interfacial tension is 3.37 mN / m, and the imbibition efficiency of the aqueous solution in the core can reach 48%.

[0008] During the process of water flooding, water is easy to displace the oil in the water-wet oil layer, but it is difficult to displace the oil in the oil-wet oil layer completely. According to the statistical data of oilfield development practice, the recovery rate of the oil-wet oil layer is only about 45% at present, while the recovery rate of the water-wet oil layer can reach 80% in some cases. For the oil-wet oil layer, since oil preferentially wets the solid surface of the rock, there is a strong adhesion force between the oil and the solid surface. When the injected water enters the oil-wet pore channels, the adhesion force between the oil and the rock surface restricts and hinders the flow of oil on the solid surface; while the viscous resistance of water is small, and it often channels along the center of the pore. If the injection rate is increased, the water channeling and bypassing effect will be more significant. When the injected water passes through the center of the pore, a film is left on the solid surface, and this oil film is one of the forms of residual oil after water flooding. The influence of the surface properties of the oil layer on the development effect is obvious. If this adverse effect occurs in the actual oil layer with relatively serious heterogeneity, it will make the influence of the intra-layer heterogeneity on the effect more sharply manifested.

[0009] In 2000, Liu Zhongyun et al. proved through water flooding experiments in "The Influence of Wettability on Recovery Rate and Relative Permeability" that the recovery rate of water-wet rocks is higher than that of oil-wet rocks, and the recovery rate of weakly water-wet rocks is the highest, followed by neutral wettability.

[0010] In 2009, Wu Tianjiang et al. showed in "The Strong Adhesion Tension of Low-Permeability and Strong Oil-Wet Pore Walls to Crude Oil" that the oil-water interfacial tension of the composite system cannot fully activate the residual oil, so the recovery rate is very low, and the recovery rate gradually increases when the hydrophilicity of the rock increases.

[0011] In 2017, Dang Hailong showed in "Research on Imbibition Displacement in Fractured Low-Permeability Oil Reservoirs in Ordos Basin" that wettability is the most important factor affecting imbibition displacement. The more hydrophilic the rock is, the greater the driving force for oil displacement and the better the oil displacement effect; the influence of boundary conditions on imbibition displacement is mainly because it changes the imbibition contact area, and the larger the imbibition contact area, the better the imbibition effect; the viscosity has a greater influence on imbibition, and the imbibition effect improves significantly with the decrease of viscosity.

[0012] In 1991, Zhao Guoxi showed in "Physical Chemistry of Surfactants" that the compound use of anionic surfactants and non-ionic surfactants can obtain better detergency, wettability and other interfacial activities than single surfactants. Liu Dexin, Huang Hongdu and others' research shows that this is not the case in all situations. In 2007, in "The Influence of Ionic Surfactants on the Interfacial Activity of Petroleum Oxidation Soap and Its Compound System", the compound research of petroleum carboxylate and its compound system with alkylbenzene sulfonate with polyoxyethylene non-ionic surfactants was carried out, and the results show that OP-type and Tween-type non-ionic surfactants with different concentrations have negative effects on the interfacial activity of petroleum carboxylate and its compound system with alkylbenzene sulfonate and Daqing crude oil.

[0013] At present, for the surfactants applied in tertiary oil recovery, whether it is the compounding of anionic and non-ionic surfactants or the compounding of anionic, cationic or zwitterionic surfactants, due to the structural composition of ion pairs and the mutual influence of different active groups, as well as the complexity in actual oilfield applications, it is very difficult to simultaneously obtain ultra-low interfacial tension and super water-wetness in actual applications. In anionic and anionic-nonionic mixed surfactants, the anions are usually sulfonate, carboxylate, and sulfate. Sulfonate has poor water solubility and is not heat-resistant. Sulfate generally hydrolyzes rapidly above 50°C. For anionic-nonionic mixed surfactants containing carboxylate and zwitterionic surfactants, the organic chlorine content is usually difficult to meet the industry application standard of less than 0.01%. The surfactants and their compounding technologies applied in tertiary oil recovery still need to be further improved and developed.

[0014] In addition, there has long been a traditional concept that cationic surfactants and anionic surfactants cannot be mixed in aqueous solutions, otherwise they will lose their surface activity or form precipitates. However, subsequent studies have shown that under appropriate conditions, anionic surfactants and cationic surfactants can be compounded and used without generating precipitates or losing surface activity. When anionic surfactants and cationic surfactants form mixed micelles in solution, there is not only the repulsion between the same charges of the ionic heads in the case of a single surfactant, but also the attraction between positive and negative ions promotes the association between the two ions.

[0015] Compound emulsions of anionic-nonionic, cationic, nonionic surfactants, alcohols, and organic bases have advantages such as good interfacial properties, wettability, and permeability. Having ultra-low interfacial tension and super water-wetness is the key to technical research. Summary of the Invention

[0016] The purpose of the present invention is to provide a preparation method and application of a displacement emulsion for oil production engineering, so as to solve the problems of poor interfacial, wetting, and salinity tolerance properties of conventional surfactant emulsions in tertiary oil recovery.

[0017] One of the objectives of the present invention is to provide the above-mentioned preparation method of the displacement emulsion for oil production engineering, which includes the following steps: successively add anionic-nonionic surfactant, cationic surfactant, surfactant compound synergist, organic phase, organic base agent, complexing agent, emulsifier, and organic chlorine remover into a container, and their molar ratio is: N(anionic-nonionic surfactant):N(cationic surfactant):N(surfactant compound synergist):N(organic phase):N(organic base agent):N(complexing agent):N(emulsifier):N(organic chlorine remover) = (0.25 - 1):1:(0.125 - 0.5):(1 - 1.5):(0.75 - 1.5):(0.125 - 0.5):(1 - 1.375):(0.75 - 1.5). Add solvent water to prepare a solution with a mass concentration of 0.00625% - 0.4%, heat and stir to 55 - 65 °C, and continuously stir at a speed of 150 - 200 revolutions per minute for 90 - 120 minutes to obtain the product.

[0018] Preferably, the anionic-nonionic surfactant includes sodium fatty alcohol polyoxyethylene ether carboxylate AEC9Na, alkylphenol polyoxyethylene ether carboxylate, and alkylphenol polyoxyethylene ether sulfonate.

[0019] Preferably, the cationic surfactant refers to a quaternary ammonium salt cationic surfactant with an alkyl R of C8 - C18, and more preferably C8 - C18 alkyltrimethylammonium chloride or C8 - C18 alkyltrimethylammonium bromide.

[0020] Preferably, the surfactant compound synergist includes coconut fatty acid diethanolamide and alkyl diethanolamine.

[0021] Preferably, the organic phase includes n-pentanol, n-hexanol, n-heptanol, and n-octanol.

[0022] Preferably, the organic base agent includes diethanolamine and triethanolamine. [[ID=I6]]

[0023] Preferably, the complexing agent includes sodium citrate and sodium ethylenediaminetetraacetate.

[0024] Preferably, the emulsifying and dispersing agent refers to a nonionic surfactant that can evenly emulsify the compounded surfactant emulsion without precipitation, and more preferably includes fatty alcohol polyoxyethylene ether AEO-9 and polyoxyethylene ether of C12 - C14 alcohols MOA-9.

[0025] Preferably, the organic chlorine remover is sodium formate or potassium formate.

[0026] Another objective of the present invention is to provide a displacement emulsion for oil production engineering prepared by the above method, whose interfacial tension against crude oil is ≤ 10 -3 mN / m, and the contact angles against quartz glass and oil-wet quartz glass are both less than 20°.

[0027] A third object of the present invention is to provide the use of the above-mentioned oil production engineering displacement emulsion in reservoir oil displacement. The oil production engineering displacement aqueous solution is prepared by formulating it into a concentration of 0.05% to 0.4% by mass and injected into the reservoir.

[0028] Further, the concentration of the oil production engineering displacement aqueous solution is 0.2 wt%.

[0029] The present invention has the following beneficial effects:

[0030] An oil production engineering displacement emulsion provided by the present invention, which is mainly aimed at the field of improving oil recovery in oilfield production engineering, has an interfacial tension with crude oil ≤ 10 -3 mN / m in the order of magnitude, reaching an ultra-low interface; the contact angles with quartz glass sheets and oil-wet quartz glass sheets are both less than 20°, reaching super-strong water-wetting; the salinity tolerance can reach 100,000 mg / l, with high salinity tolerance; and the oil displacement effect in field application is obvious. Description of the Drawings

[0031] Figure 1 It is a schematic diagram of the interfacial tension between displacement emulsions with different concentrations prepared in Example 1 and crude oil;

[0032] Figure 2 It is a schematic diagram of the contact angle of displacement emulsions with different concentrations prepared in Example 1 with oil-wet quartz glass sheets;

[0033] Figure 3 It is a schematic diagram of the interfacial tension between displacement emulsions with different concentrations prepared in Example 2 and crude oil;

[0034] Figure 4 It is a schematic diagram of the contact angle of displacement emulsions with different concentrations prepared in Example 2 with oil-wet quartz glass sheets;

[0035] Figure 5 It is a schematic diagram of the interfacial tension between displacement emulsions with different concentrations prepared in Example 3 and crude oil;

[0036] Figure 6 It is a schematic diagram of the contact angle of displacement emulsions with different concentrations prepared in Example 3 with oil-wet quartz glass sheets. Detailed Embodiments

[0037] In order to make the objectives, technical solutions and advantages of the present invention clearer and more definite, the following describes it specifically in combination with examples. It should be noted that the following examples are only used to explain and illustrate the present invention and are not used to limit the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above-mentioned invention content still fall within the protection scope of the present invention.

[0038] Example 1

[0039] A preparation method of displacement emulsion for oil production engineering, which is compounded by sodium fatty alcohol polyoxyethylene ether carboxylate AEC9Na, octadecyl trimethyl ammonium chloride, coconut fatty acid diethanolamide, n-pentanol, triethanolamine, sodium citrate, lauryl alcohol polyoxyethylene ether MOA-9, and sodium formate. In a container, 0.005 mol of sodium fatty alcohol polyoxyethylene ether carboxylate AEC9Na, 0.02 mol of octadecyl trimethyl ammonium chloride, 0.01 mol of coconut fatty acid diethanolamide, 0.02 mol of n-pentanol, 0.015 mol of triethanolamine, 0.0025 mol of sodium citrate, 0.02 mol of lauryl alcohol polyoxyethylene ether MOA-9, and 0.015 mol of sodium formate are added in sequence. The molar ratio is: N(sodium fatty alcohol polyoxyethylene ether carboxylate AEC9Na):N(octadecyl trimethyl ammonium chloride):N(coconut fatty acid diethanolamide):N(n-pentanol):N(triethanolamine):N(sodium citrate):N(lauryl alcohol polyoxyethylene ether MOA-9):N(sodium formate) = 0.25:1:0.5:1:0.75:0.125:1:0.75. Then, the remaining solvent water is added to make the mass of the prepared emulsion 100 g. Heat and stir to 55 - 65 °C, and continuously stir at a speed of 150 - 200 revolutions per minute for 90 - 120 minutes to obtain a displacement emulsion for oil production engineering.

[0040] The aqueous solutions of the displacement emulsion for oil production engineering with different mass concentrations of 0.00625% - 0.4% are prepared, and the interfacial tension and wettability are measured respectively. Under the condition of a temperature of 95 °C, as the concentration increases, the interfacial tension changes by orders of magnitude. When the mass concentration is 0.05%, the interfacial tension between the displacement emulsion for oil production engineering and the crude oil of Z13 oilfield can reach -3 the order of magnitude of 10 -4 mN / m. When the mass concentration is 0.4%, the interfacial tension between the displacement emulsion 1 for oil production engineering and the crude oil of Z13 oilfield is Figure 1 of the order of magnitude of 10 Figure 2 mN / m, as shown in

[0041] For the oil-wet quartz glass sheet, as the concentration increases, the wetting angle gradually increases. When the mass concentration is 0.4%, the contact angle is 3°. When the mass concentration is 0.00625%, the contact angle is 44°. While the wetting angle of clear water on the oil-wet core is 80.2°, as shown in

[0042] Example 2

[0043] A preparation method of displacement emulsion for oil production engineering, which is compounded by sodium alkylphenol polyoxyethylene ether carboxylate AEC9Na, cetyl trimethyl ammonium chloride, coconut fatty acid diethanolamide, n-hexanol, diethanolamine, tetrasodium ethylenediaminetetraacetate, fatty alcohol polyoxyethylene ether AEO-9, and potassium formate. Add 0.01 mol of sodium alkylphenol polyoxyethylene ether carboxylate AEC9Na, 0.02 mol of cetyl trimethyl ammonium chloride, 0.005 mol of coconut fatty acid diethanolamide, 0.03 mol of n-hexanol, 0.02 mol of diethanolamine, 0.005 mol of tetrasodium ethylenediaminetetraacetate, 0.025 mol of fatty alcohol polyoxyethylene ether AEO-9, and 0.02 mol of potassium formate into a container in sequence. The molar ratio is: N(sodium alkylphenol polyoxyethylene ether carboxylate AEC9Na):N(cetyl trimethyl ammonium chloride 1631):N(coconut fatty acid diethanolamide 6501):N(n-hexanol):N(diethanolamine):N(tetrasodium ethylenediaminetetraacetate):N(fatty alcohol polyoxyethylene ether AEO-9):N(potassium formate)=0.5:1:0.25:1.5:1:0.25:1.25:1. Add the remaining solvent water to make the mass of the prepared emulsion 100 g. Heat and stir to 60 °C, and continuously stir at a speed of 150 revolutions per minute for 90 minutes to obtain a displacement emulsion for oil production engineering.

[0044] Prepare aqueous solutions of displacement emulsion for oil production engineering with different mass concentrations of 0.00625% - 0.4%, and measure the interfacial tension and wettability respectively. Under the condition of a temperature of 95 °C, as the concentration increases, the interfacial tension changes by orders of magnitude. When the mass concentration is 0.05%, the interfacial tension between the displacement emulsion for oil production engineering and the crude oil of Z13 oilfield can reach -3 the order of magnitude of 10 -5 mN / m. When the mass concentration is 0.4%, the interfacial tension between the displacement emulsion for oil production engineering and the crude oil of Z13 oilfield reaches Figure 3 the order of magnitude of 10 Figure 4 mN / m, as shown

[0045] Under the condition of a temperature of 95 °C, when the salinity of the aqueous solution reaches 100000 mg / l, there is no micro-turbidity phenomenon.

[0046] Example 3

[0047] A preparation method of displacement emulsion for oil production engineering, which is compounded by sodium alkylphenol polyoxyethylene ether sulfonate, dodecyl trimethyl ammonium chloride, dodecyl diethanolamine, n-octanol, diethanolamine, tetrasodium ethylenediaminetetraacetate, polyoxyethylene ether of C12-14 alcohol MOA-9, and sodium formate. In a container, 0.02 mol of sodium alkylphenol polyoxyethylene ether sulfonate, 0.02 mol of dodecyl trimethyl ammonium chloride, 0.0025 mol of dodecyl diethanolamine, 0.02 mol of n-octanol, 0.03 mol of diethanolamine, 0.01 mol of tetrasodium ethylenediaminetetraacetate, 0.0275 mol of polyoxyethylene ether of C12-14 alcohol MOA-9, and 0.03 mol of sodium formate are added in sequence. The molar ratio is: N(sodium alkylphenol polyoxyethylene ether sulfonate):N(dodecyl trimethyl ammonium chloride):N(dodecyl diethanolamine):N(n-octanol):N(diethanolamine):N(tetrasodium ethylenediaminetetraacetate):N(polyoxyethylene ether of C12-14 alcohol MOA-9):N(sodium formate) = 1:1:0.125:1:1.5:0.5:1.375:1.5. Then the remaining solvent water is added to make the mass of the prepared emulsion 100 g. Heat and stir to 65 °C, and continuously stir at a speed of 200 revolutions per minute for 120 minutes to obtain a displacement emulsion for oil production engineering.

[0048] The displacement emulsion aqueous solution for oil production engineering with different mass concentrations of 0.00625% - 0.4% is prepared, and the interfacial tension and wettability are measured respectively. Under the condition of a temperature of 95 °C, as the concentration increases, the interfacial tension changes by orders of magnitude. When the mass concentration ≥ 0.05%, the interfacial tension between the displacement emulsion for oil production engineering and the crude oil in Z13 oilfield can reach the order of magnitude of 10 -3 mN / m, as Figure 5 shown; for the oil-wet quartz glass sheet, as the concentration increases, the wetting angle gradually increases. The contact angle is 3.1° when the mass concentration is 0.4%, and the contact angle is 30.3° when the mass concentration is 0.00625%. While the wetting angle of clear water on the oil-wet core is 80.2°, as Figure 6 shown.

[0049] Under the condition of a temperature of 95 °C, there is no micro-turbidity phenomenon when the salinity of the aqueous solution reaches 100000 mg / l.

[0050] Example 4

[0051] The oil-bearing formation of Well Group S5-5 is E1f2, with an oil-bearing area of 1.13 km 2 , and the geological reserves are 60×10 4 t, and the recovery factor is 12.1%. The reservoir depth of the injection well in Well Group S5-5 is 2200 m - 2220 m, and the temperature is 87.5 °C. The reservoir porosity is 13.1%, and the permeability is 7.9×10 -3 μm 2, it is a low-porosity and extra-low permeability reservoir. Prepare an aqueous solution of the oil production engineering displacement emulsion provided in Example 2 with a mass concentration of 0.2%, and the interfacial tension with crude oil is 1.5×10 -4 mN / m, the daily water injection volume is 35m 3 / d, the injection volume is 12,000 m 3 , and the cumulative oil increment is 1528t, and the oil displacement effect is obvious.

[0052] In the description of this specification, the descriptions referring to terms such as "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0053] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification to better explain the principles and practical applications of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A preparation method for an oil production engineering displacement emulsion, characterized in that It includes the following steps: sequentially add anionic-nonionic surfactant, cationic surfactant, surfactant compound synergist, organic phase, organic base agent, complexing agent, emulsifier, and organic chlorine remover into a container, and their molar ratio is: N(anionic-nonionic surfactant):N(cationic surfactant):N(surfactant compound synergist):N(organic phase):N(organic base agent):N(complexing agent):N(emulsifier):N(organic chlorine remover) = (0.25 - 1):1:(0.125 - 0.5):(1 - 1.5):(0.75 - 1.5):(0.125 - 0.5):(1 - 1.375):(0.75 - 1.5). Add solvent water to prepare a solution with a mass concentration of 0.00625% - 0.4%, heat and stir to 55 - 65 °C, and continuously stir at a speed of 150 - 200 revolutions per minute for 90 - 120 minutes to obtain it; The anionic-nonionic surfactant includes sodium fatty alcohol polyoxyethylene ether carboxylate AEC9Na, alkylphenol polyoxyethylene ether carboxylate, and alkylphenol polyoxyethylene ether sulfonate; The cationic surfactant refers to a quaternary ammonium salt cationic surfactant with an alkyl R of C8 - C18; The surfactant compound synergist includes coconut diethanolamide and alkyl diethanolamine; The organic phase includes n-pentanol, n-hexanol, n-heptanol, and n-octanol; The organic chlorine remover is sodium formate or potassium formate; The emulsifier includes fatty alcohol polyoxyethylene ether AEO-9 and lauryl alcohol polyoxyethylene ether MOA-9; 2. The preparation method of an oil displacement emulsion for an oil production engineering according to claim 1, wherein The cationic surfactant is C8 - C18 alkyl trimethyl ammonium chloride or C8 - C18 alkyl trimethyl ammonium bromide; 3. A method for preparing a displacement emulsion in oil production engineering according to claim 1, characterized in that, The organic base agent includes diethanolamine and triethanolamine; 4. A method for preparing a displacement emulsion in oil production engineering according to claim 1, characterized in that, The complexing agent includes sodium citrate and sodium ethylenediaminetetraacetate; 5. The oil production engineering displacement emulsion prepared by any of the methods according to claims 1-4, characterized in that, When the mass concentration of the displacement emulsion in the oil production engineering is 0.05% - 0.4%, the interfacial tension against crude oil is ≤ 10 -3 mN / m, and the contact angles with the quartz glass sheet and the oil-wet quartz glass sheet are both less than 20°.

6. Use of the displacement emulsion in oil production engineering in reservoir oil displacement according to claim 5, characterized in that, Prepare it into an oil production engineering displacement aqueous solution with a mass concentration of 0.00625% - 0.4% and inject it into the reservoir; 7. The use according to claim 6, wherein The concentration of the oil production engineering displacement aqueous solution is 0.2 wt%;

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