Viscosity-reducing and permeability-increasing non-ultralow interface dialysis oil displacement agent and preparation method thereof

Abstract

The invention discloses a viscosity-reducing and permeability-increasing non-ultralow interface dialysis oil-displacing agent and a preparation method thereof. The viscosity-reducing and permeability-increasing non-ultralow interface dialysis oil-displacing agent is prepared from the following raw materials in parts by weight: 0.1 to 0.5 percent of SS basic oil-displacing agent, 0.3 to 0.7 percent of nonionic surfactant, 0.5 to 2 percent of dialysis enhanced slow-release agent, 0.01 to 0.2 percent of cosurfactant and the balance of water, the dialysis enhanced slow-release agent is a supermolecule compound formed by combining limonene or citral with beta-cyclodextrin. The oil-displacing agent disclosed by the invention not only improves the recovery ratio, so that a large number of oil-water transition layers do not appear in produced liquid, but also reduces the interfacial tension by one order of magnitude, and improves the comprehensive oil-displacing efficiency.

Description

Technical Field

[0001] The invention relates to a technology for improving the recovery rate of viscous crude oil in low-permeability oil reservoirs, and in particular to a non-ultra-low interface dialysis oil-displacing agent for reducing viscosity and increasing permeability and a preparation method thereof. Background Art

[0002] During the development of oil fields, the low-viscosity crude oil, which was mainly composed of light components in the early stage, was affected by the chromatographic effect, and the proportion of crude oil components changed. The proportion of colloid and asphalt gradually increased, the viscosity of crude oil increased, the permeability became worse, and the oil-water viscosity ratio became larger, which had an important impact on the recovery rate, resulting in increased difficulty in mining. Faced with the problem of how to improve the recovery rate of viscous residual oil in water drive, simple water injection alone can no longer maintain a high recovery efficiency. Reasonable measures must be taken to repair the formation crude oil environment and find the most reasonable method to improve the recovery rate. With the deepening of the oil field development stage, the dialysis flooding technology can not only improve the sweep coefficient in the displacement process but also improve the oil washing efficiency of low-permeability cores, and has achieved success in industrial application and large-scale field tests.

[0003] In this context, it is necessary to study the dialysis oil displacement agent under specific formation environmental conditions. Through targeted formulation research, the corresponding oil displacement agent formula is developed, the appropriate oil displacement conditions are found, and the goal of reducing the viscosity and increasing the efficiency of crude oil under existing conditions is achieved. At present, the dialysis-fracturing method is often used to transform the formation to achieve the effect of reducing pressure and increasing permeability. However, the dialysis agents used in the dialysis-fracturing method are mostly compound agents of ultra-low interfacial tension surfactants. Its advantage is that it can quickly emulsify the low-permeability formation crude oil after a period of well soaking, and then the crude oil is extracted from the ground through water injection, with significant oil production effect. However, the ultra-low interfacial tension oil displacement agent will undergo transitional emulsification with the crude oil, producing an excessive amount of oil-water intermediate transition layer, especially for blocks in the middle and late stages of development, the viscosity of the crude oil increases, the proportion of the oil-water transition layer further increases, and the effective recovery rate decreases, resulting in an increase in the processing cost of crude oil in the later stage.

[0004] Patent CN110951473A is affected by inorganic salts, and the interfacial tension cannot be reduced to the ideal state. Due to the long stirring time, the atomic economy is greatly reduced, which increases the difficulty of product production; Patent CN116410726A is a high content of chemical agents in the formula, which is retained in the oil layer, causing pollution and blockage to the reservoir. The demulsification effect of the oil displacement agent is not considered, and a large amount of oil-water emulsified transition layer appears in the produced fluid, which will hinder the improvement of oil displacement efficiency; Patent CN102277149A has a complex formula composition, and multiple reagents are mixed or organically synthesized, which greatly increases the complexity of implementation and the difficulty of cost control. At the same time, the formula reaction conditions require complex requirements, and there are many reagent residues; Patent CN102977872A has a large water-oil mobility ratio of the oil displacement agent, and the crude oil viscosity is not reduced. Due to the increase in the viscosity of the oil displacement agent, the oil-water interfacial tension is hindered, affecting the oil displacement efficiency; Patent CN109652048B has a complex formula composition, and multiple reagents are mixed or organically synthesized, which greatly increases the complexity of implementation and the difficulty of cost control. At the same time, the formula reaction conditions require complex, and there are more reagent residues, which increases the damage to the formation and the difficulty of post-processing of the produced fluid; the patent CN107365574A oil displacement agent has harsh reaction conditions, more reaction steps, and long reaction time, which increases the difficulty of production, and is applicable to limited reservoir conditions. There are requirements for temperature, formation water mineralization, calcium and magnesium ion concentrations, and underground crude oil viscosity. The cost of some raw materials is high, and the required production cost increases exponentially, further reducing the economic efficiency, which is not conducive to the actual promotion and application. The oil displacement agent contains inorganic salts, which increases certain formation damage; the chemical agent composition in the patent CN109233779A is complex and the content is large, which increases the processing cost in the produced fluid; A large amount of oil-water emulsified transition layer appears in the produced fluid, which will hinder the improvement of oil recovery efficiency; Patent CN117736714A is affected by high alkalinity, the interfacial tension cannot be reduced to an ideal state, the demulsification time is long, the demulsification rate is low, and the corresponding demulsifier needs to be added, which increases the operating cost; Patent CN101824313B uses a large amount of salt and alkali in this formula, which will cause excessive formation damage, the cost of some raw materials is high, the demulsification effect of the oil recovery agent is poor, and a large amount of oil-water emulsified transition layer appears in the produced fluid; Patent CN105038752A oil recovery agent has many synthesis steps, a long stirring time, affected stability, high inorganic salt content, and the interfacial tension cannot be reduced to an ideal state, affecting the oil recovery efficiency.

[0005] Therefore, it is necessary to ensure that the dialysis oil-displacing agent can quickly reduce the emulsification of the crude oil in the seepage formation after a period of well soaking, and can quickly demulsify after production to prevent excessive emulsification and reduce the content of the oil-water intermediate transition layer. At the same time, the interfacial tension, compatibility, viscosity reduction effect, demulsification effect and other properties of the dialysis agent are good, and the static dialysis effect is optimized, the recovery rate is increased, and the comprehensive oil recovery efficiency is improved. It is extremely necessary to develop a monoterpene non-ultra-low interface chemical oil-displacing agent that can reduce crude oil viscosity, increase recovery rate, and produce fluids without a large amount of oil-water transition layer. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a non-ultra-low interface dialysis oil-displacing agent for reducing viscosity and increasing permeability. The dialysis enhancement slow-release agent in the non-ultra-low interface chemical oil-displacing agent can prevent the effective ingredients of the formula from prematurely releasing the dialysis enhancement agent before entering the target layer to contact with the non-ionic surfactant in the solution, so that the solubility of the two decreases, resulting in the dialysis oil-displacing agent not having a large amount of oil-water transition layer. The actual effect is greatly reduced. Slowly releasing the dialysis enhancement agent can achieve the purpose of reducing crude oil viscosity, repairing formation permeability, improving recovery, and preventing a large amount of oil-water transition layer from appearing in the produced fluid, thereby improving the effective recovery rate.

[0007] A non-ultra-low interface dialysis oil-displacing agent for reducing viscosity and increasing permeability comprises the following raw material components in parts by weight: 0.1% to 0.5% of SS basic oil-displacing agent, 0.3% to 0.7% of nonionic surfactant, 0.5% to 2% of dialysis enhancement sustained-release agent, 0.01% to 0.2% of auxiliary surfactant, and the remaining components are water.

[0008] Preferably, the dialysis enhancing sustained-release agent is a supramolecular compound of limonene or citral combined with β-cyclodextrin.

[0009] Preferably, the dialysis enhanced sustained-release agent is prepared according to the following method: an ethanol solution of limonene or citral is mixed with an aqueous solution of β-cyclodextrin, and the mixture is stirred and reacted at a temperature of 35° C. to 45° C. for 2 hours.

[0010] Preferably, the molar ratio of the limonene or citral to β-cyclodextrin is 1:(5-15).

[0011] Preferably, the nonionic surfactant is coconut oil diethanolamide.

[0012] Preferably, the concentration of the limonene or citral ethanol solution is 30%.

[0013] Preferably, the co-surfactant is ethanol, n-butanol or isobutanol.

[0014] A method for preparing a viscosity-reducing and permeability-increasing non-ultra-low interfacial dialysis oil-displacing agent, the preparation method comprising: sequentially adding an SS basic oil-displacing agent, a nonionic surfactant, a dialysis enhancement sustained-release agent and a co-surfactant into an aqueous solution, controlling the temperature at 35° C. to 45° C. and stirring the reaction for 1 hour to obtain a viscosity-reducing and permeability-increasing non-ultra-low interfacial dialysis oil-displacing agent.

[0015] Beneficial effects of the present invention: (1) The addition of the dialysis enhancer sustained-release agent effectively solves the problem that the dialysis enhancers limonene and citral are easy to volatilize and lose quickly, and produce turbid insoluble matter when mixed with other chemical agents, especially non-ionic surfactants, resulting in loss of effective ingredients and affecting the maximum effect of the dialysis oil displacement agent; (2) The oil displacement agent of the present invention not only improves the recovery rate and eliminates the presence of a large amount of oil-water transition layer in the produced fluid, but also reduces the interfacial tension by an order of magnitude, thereby improving the overall oil displacement efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a comparison diagram of the crude oil transition layer produced in Example 3 and Comparative Example 3. DETAILED DESCRIPTION

[0017] The SS base oil displacing agent in the present invention is the one described in CN116355603A.

[0018] Example 1 Slowly adding a 30% limonene ethanol solution into a β-cyclodextrin aqueous solution at a molar ratio of 1:10, and stirring the solution at 35°C for 2 hours to obtain a dialysis-enhanced sustained-release agent; A non-ultra-low interface dialysis oil displacement agent for reducing viscosity and increasing permeability, comprising 0.1% of SS basic oil displacement agent, 0.3% of nonionic surfactant, 0.75% of dialysis enhancement slow-release agent, 0.1% of co-surfactant, and the remaining components are water; The nonionic surfactant is coconut oil diethanolamide; The co-surfactant is ethanol; A method for preparing a viscosity-reducing and permeability-increasing non-ultra-low interface dialysis oil-displacing agent: an SS basic oil-displacing agent, a non-ionic surfactant, a dialysis enhancement sustained-release agent and a co-surfactant are sequentially added into an aqueous solution, the temperature is controlled at 45° C. and the reaction is stirred for 1 hour to obtain a viscosity-reducing and permeability-increasing non-ultra-low interface dialysis oil-displacing agent.

[0019] Example 2 Slowly adding a 30% limonene ethanol solution into a β-cyclodextrin aqueous solution at a molar ratio of 1:5, and stirring the mixture at 40°C for 2 hours to obtain a dialysis-enhanced sustained-release agent; A non-ultra-low interface dialysis oil displacement agent for reducing viscosity and increasing permeability, comprising 0.3% of SS basic oil displacement agent, 0.3% of nonionic surfactant, 0.5% of dialysis enhancement slow-release agent, 0.01% of co-surfactant, and the remaining components are water; The co-surfactant is n-butanol; A method for preparing a viscosity-reducing and permeability-increasing non-ultra-low interfacial dialysis oil-displacing agent: an anionic surfactant, a nonionic surfactant, a dialysis enhancing sustained-release agent and a co-surfactant are sequentially added into an aqueous solution, the temperature is controlled at 43° C. and the reaction is stirred for 1 hour to obtain a viscosity-reducing and permeability-increasing non-ultra-low interfacial dialysis oil-displacing agent.

[0020] Example 3 Slowly adding a 30% limonene ethanol solution into a β-cyclodextrin aqueous solution at a molar ratio of 1:12, and stirring the mixture at 45°C for 2 hours to obtain a dialysis-enhanced sustained-release agent; A non-ultra-low interface dialysis oil displacement agent for reducing viscosity and increasing permeability, comprising 0.5% of SS basic oil displacement agent, 0.5% of nonionic surfactant, 1% of dialysis enhancement slow-release agent, 0.1% of auxiliary surfactant, and the remaining components are water; The co-surfactant is isobutanol; A method for preparing a viscosity-reducing and permeability-increasing non-ultra-low interface dialysis oil-displacing agent: an anionic surfactant, a nonionic surfactant, a dialysis enhancing sustained-release agent and a co-surfactant are sequentially added into an aqueous solution, the temperature is controlled at 40° C. and the reaction is stirred for 1 hour to obtain a viscosity-reducing and permeability-increasing non-ultra-low interface dialysis oil-displacing agent.

[0021] Example 4 Limonene was replaced by citral, and the molar ratio of citral to β-cyclodextrin was 1:8. Other details were the same as in Example 3.

[0022] Example 5 Limonene was replaced by citral, and the molar ratio of citral to β-cyclodextrin was 1:15. Others were the same as in Example 3.

[0023] Example 6 A viscosity-reducing and permeability-increasing non-ultra-low interface dialysis oil-displacing agent comprises 0.5% of SS basic oil-displacing agent, 0.7% of nonionic surfactant, 1% of dialysis enhancement sustained-release agent, 0.2% of co-surfactant, and the remaining components are water; the other components are the same as those in Example 3.

[0024] Example 7 A viscosity-reducing and permeability-increasing non-ultra-low interface dialysis oil-displacing agent comprises 0.4% SS basic oil-displacing agent, 0.4% nonionic surfactant, 2% dialysis enhancement sustained-release agent, 0.2% co-surfactant, and the remaining components are water; the other components are the same as those in Example 3.

[0025] Example 8 A viscosity-reducing and permeability-increasing non-ultra-low interface dialysis oil-displacing agent comprises 0.5% of SS basic oil-displacing agent, 0.5% of nonionic surfactant, 2% of dialysis enhancement sustained-release agent, 0.2% of co-surfactant, and the remaining components are water; the other components are the same as those in Example 3.

[0026] Comparative Example 1 No dialysis enhancement sustained release agent was added, and the rest was the same as in Example 3.

[0027] Comparative Example 2 No β-cyclodextrin was added to the dialysis enhanced sustained release agent, and the other steps were the same as those in Example 3.

[0028] Comparative Example 3 No nonionic surfactant was added, and the rest was the same as in Example 3.

[0029] Comparative Example 4 The SS basic oil-displacing agent was replaced by fatty alcohol polyoxypropylene polyoxyethylene ether sulfate, and the rest was the same as in Example 3.

[0030] Performance testing: K100 surface tension meter, at 25℃, add 30ml oil displacement agent and 20ml kerosene into a beaker, and test the results. See Table 1. Detection of interfacial tension: Use KRUSS, Germany; Viscosity test: Using a six-speed viscometer at 200 rpm, the crude oil with a viscosity of 21 MPa·s and the oil displacement agent with an oil-water ratio of 20% were tested. The results are shown in Table 1. Analysis of displacement experiment: Simulating the dialysis oil displacement environment, the dialysis oil displacement agent was slowly injected into the core 3.5mD (less than 5mD) device filled with low permeability saturated crude oil with a viscosity of 21mPa·s. Under the condition of displacement speed of 0.017mm / s (less than 0.78mm / s), it was able to simultaneously meet the evaluation of its dialysis and oil displacement performance. In the core with a viscosity of 21mPa·s and a permeability of 3.5mD at 30℃, under the condition of low speed (0.017mm / s), the recovery factors of the embodiment and comparative examples 1, 2, and 3 are shown in Table 1; Table 1 Interfacial tension, emulsion viscosity and recovery factor test Example 3 increases the recovery rate by 6.4%, 5.1% and 8.7% relative to Comparative Example 1, Comparative Example 2 and Comparative Example 3, and the increase ratio reaches 65.31%, 45.95% and 116%. The recovery rate of Example 3 increases by only 11.0% relative to Comparative Example 4, indicating that when the oil displacement agent increases the recovery rate of crude oil with a certain viscosity, it is less affected by the SS basic oil displacement agent or fatty alcohol polyoxypropylene polyoxyethylene ether sulfate, but is affected by the ability of non-ionic surfactants to reduce interfacial tension and demulsification, and the ability of dialysis enhanced sustained-release agents to dissolve colloids and asphaltene, the main factors affecting viscosity.

[0031] At the same time, the crude oil transition layer produced in Example 3 and Comparative Example 3 is compared. Figure 1 ,from Figure 1It can be seen that in the comparative example 3 without adding nonionic surfactant, a large number of transition layers appeared, which had a significant impact on the final recovery rate results. However, there was almost no transition layer in the example 3, and the emulsion was naturally stratified during the floating process, with excellent performance.

Claims

1. A non-ultra-low interface dialysis oil displacement agent for reducing viscosity and increasing permeability, characterized in that: The invention is composed of the following raw materials in parts by weight: 0.1% to 0.5% of SS basic oil displacement agent, 0.3% to 0.7% of nonionic surfactant, 0.5% to 2% of dialysis enhanced slow-release agent, 0.01% to 0.2% of auxiliary surfactant, and the remaining components are water.

2. According to claim 1, a non-ultra-low interfacial dialysis oil displacement agent for reducing viscosity and increasing permeability, characterized in that: The dialysis enhanced sustained-release agent is a supramolecular compound of limonene or citral combined with beta-cyclodextrin.

3. A non-ultra-low interfacial dialysis oil displacement agent for reducing viscosity and increasing permeability according to claim 2, characterized in that: The dialysis enhanced sustained-release agent is prepared according to the following method: an ethanol solution of limonene or citral is mixed with an aqueous solution of β-cyclodextrin, and the mixture is stirred and reacted for 2 hours under the condition of controlling the temperature at 35° C. to 45° C.

4. A non-ultra-low interfacial dialysis oil displacement agent for reducing viscosity and increasing permeability according to claim 3, characterized in that: The molar ratio of the limonene or citral to β-cyclodextrin is 1:(5-15).

5. A non-ultra-low interfacial dialysis oil displacement agent for reducing viscosity and increasing permeability according to claim 4, characterized in that: The nonionic surfactant is coconut oil diethanolamide.

6. A non-ultra-low interfacial dialysis oil displacement agent for reducing viscosity and increasing permeability according to claim 5, characterized in that: The concentration of the ethanol solution of limonene or citral is 30%.

7. A non-ultra-low interfacial dialysis oil displacement agent for reducing viscosity and increasing permeability according to claim 6, characterized in that: The co-surfactant is ethanol, n-butanol or isobutanol.

8. A method for preparing the viscosity-reducing and permeability-increasing non-ultra-low interfacial dialysis oil-displacing agent according to claim 1, characterized in that: The preparation method comprises the following steps: adding an SS basic oil displacement agent, a nonionic surfactant, a dialysis enhancement sustained-release agent and a co-surfactant into an aqueous solution in sequence, stirring and reacting for 1 hour under the condition of controlling the temperature at 35° C. to 45° C., and obtaining a non-ultra-low interface dialysis oil displacement agent for reducing viscosity and increasing permeability.

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