Shale oil reservoir imbibition oil extraction agent, preparation method and application

Abstract

The invention discloses a shale oil reservoir imbibition oil extraction agent. The problems that the wettability of a shale reservoir is difficult to change and the imbibition efficiency is low when a single surfactant system is adopted in the prior art are mainly solved. The cleaning agent is characterized by comprising the following components in percentage by mass: a nonionic surfactant, a sulfate-based anionic surfactant and a sulfonic acid-based anionic surfactant, wherein the total mass concentration of the nonionic surfactant, the sulfate-based anionic surfactant and the sulfonic acid-based anionic surfactant is 0.5-1%; the mass ratio is 1: (0.5-3): (0.5-3); the concentration of the mineralized water is 1000 to 5000 ppm; the preparation method comprises the following steps: 1) adding a nonionic surfactant alkyl glycoside, a sulfate-based anionic surfactant and a sulfonic-based anionic surfactant into mineralized water in proportion to prepare a high-concentration surfactant system; and 2) diluting the high-concentration surfactant to a target concentration, and completely dissolving the solution by stirring at 45 DEG C. The imbibition oil extraction agent can effectively reduce the oil-water interfacial tension, change the wettability of a reservoir and improve the imbibition efficiency of shale oil reservoirs.

Description

Technical field:

[0001] The present invention relates to the technical field of shale oil extraction, and in particular to a shale oil reservoir imbibition oil extraction agent, a preparation method and an application thereof. Background technology:

[0002] The development and utilization of shale oil and gas reservoirs is a major revolution in the field of fossil energy. my country has rich shale oil and gas reserves, ranking third in the world. Shale oil reservoirs widely develop nanoscale pore throat systems, with pore diameters generally ranging from 50nm to 300nm, and are characterized by low porosity and low permeability. Under conventional drilling conditions, it is difficult for oil in the pores to seep out, and fracturing transformation technology is an effective means of shale oil extraction.

[0003] Fracturing transformation technology is a method of large-scale volume fracturing that increases the oil-water replacement area. The fluid undergoes oil-water imbibition displacement in the reservoir, displacing non-wetting phase crude oil to achieve the purpose of increasing shale oil recovery. Current research shows that imbibition displacement is one of the most important mechanisms for shale oil production. The premise for oil-water imbibition displacement is that the wettability of the shale oil reservoir is neutral or hydrophilic. Shale oil is a typical source-reservoir system. Shale is both an oil-producing rock and a reservoir, and is often oil-wet. Therefore, changing the wettability of the reservoir is the key to improving the efficiency of imbibition displacement of shale oil reservoirs.

[0004] In recent years, people have found that injecting surfactants into the reservoir can effectively change the wettability of the shale reservoir, give full play to the oil-water imbibition and replacement effect of the shale reservoir, and improve the recovery rate of shale oil.

[0005] At present, it is difficult for a single surfactant system to change the wettability of shale reservoirs, and the imbibition efficiency is low.

[0006] Therefore, the present invention uses nonionic surfactant and anionic surfactant as raw materials to develop a compound surfactant system as an imbibition oil recovery agent, which can effectively reduce the oil-water interfacial tension and change the wettability of the reservoir, and is of great significance to improving the recovery rate of shale oil reservoirs. Summary of the invention:

[0007] The purpose of the present invention is to overcome the problem that it is difficult to change the wettability of shale reservoirs and the imbibition efficiency is low in the existing single surfactant system in the background technology, and to provide a shale oil reservoir imbibition oil recovery agent. The shale oil reservoir imbibition oil recovery agent can effectively reduce the oil-water interfacial tension and change the wettability of the reservoir, thereby improving the recovery rate of the shale oil reservoir. The present invention also provides a preparation method and application of the shale oil reservoir imbibition oil recovery agent.

[0008] In order to achieve the above-mentioned purpose, the first aspect of the present invention provides a shale oil reservoir imbibition oil recovery agent, wherein the components and proportions thereof are as follows in terms of mass ratio: the total mass concentration of nonionic surfactant, sulfate-based anionic surfactant and sulfonic acid-based anionic surfactant is 0.5-1%, and the mass ratio is 1:(0.5-3):(0.5-3); the concentration of mineralized water is 1000-5000ppm.

[0009] Preferably, the nonionic surfactant is alkyl polyglycoside (APG), and its molecular structure is as follows:

[0010]

[0011] R1 is C 10 ~C 12 Any of the alkyl groups.

[0012] Preferably, the sulfate-based anionic surfactant is one or a mixture of two or more of sodium dodecyl sulfate (SLS), sodium hexadecyl sulfate (SCS), and sodium dodecyl alcohol polyoxyethylene ether sulfate (AES).

[0013] Preferably, the sulfonic acid anionic surfactant is one or a mixture of two or more of sodium dodecyl sulfonate (SDS), sodium dodecylbenzene sulfonate (SDBS), and sodium hexadecyl sulfonate (SHS).

[0014] Preferably, the total mass concentration of the nonionic surfactant, the sulfate-based anionic surfactant, and the sulfonic acid-based anionic surfactant is 0.6-0.8%.

[0015] Preferably, the mass ratio of the nonionic surfactant alkyl polyglycoside to the sulfate-based anionic surfactant and the sulfonic acid-based anionic surfactant is 1:(1-2):(1-2).

[0016] Preferably, the concentration of the mineralized water is 1000-4000 ppm.

[0017] Another aspect of the present invention provides a method for preparing a shale oil reservoir imbibition oil recovery agent, comprising the following steps:

[0018] (1) adding nonionic surfactant alkyl polyglycoside (APG), sulfate-based anionic surfactant and sulfonic acid-based anionic surfactant to mineralized water in proportion to prepare a high-concentration surfactant system;

[0019] (2) The high concentration surfactant is then diluted to the target concentration, and the solution is stirred at 40-50°C and 400 rpm for 1 hour to completely dissolve it.

[0020] Preferably, the target concentration is 0.01-0.4%.

[0021] A third aspect of the present invention provides an application of a shale oil reservoir imbibition oil recovery agent in a fracturing and oil recovery process.

[0022] Preferably, the specific application method is:

[0023] The above-mentioned shale imbibition agent is injected into the ground to reduce the oil-water interfacial tension, and the shale reservoir with oil-wet wettability is treated to water-wet wettability, which effectively improves the imbibition efficiency of the shale oil reservoir.

[0024] Compared with the above background technology, the present invention has the following beneficial effects:

[0025] 1. The present invention selects nonionic surfactant alkyl polyglycoside (APG) and sulfate / sulfonate anionic surfactant to construct a composite surfactant system. Compared with cationic surfactants and amphoteric surfactants, the composite surfactant system can effectively reduce the oil-water interfacial tension, change the lipophilicity of shale to hydrophilicity, and improve the imbibition efficiency.

[0026] 2. The product of the present invention introduces sulfonic acid groups to improve salt resistance and temperature resistance.

[0027] 3. The product of the present invention introduces a highly hydrophilic sulfate-based anionic surfactant, which makes it easier to change the wettability of the reservoir.

[0028] 4. The raw materials of the present invention are easily available, the preparation process is simple, and industrial production can be easily realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0030] Figure 1 The rock-water-oil contact angle of the embodiment of the present invention;

[0031] Figure 2 This is the imbibition oil recovery efficiency curve of the composite surfactant system implemented in the present invention. Specific implementation method:

[0032] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0033] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0034] The present invention is further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0035] The present invention provides a shale oil reservoir imbibition oil recovery agent, wherein the components and proportions thereof are as follows in terms of mass ratio: the total mass concentration of nonionic surfactant, sulfate-based anionic surfactant and sulfonic acid-based anionic surfactant is 0.5-1%, preferably 0.6-0.8%; the mass ratio is 1:(0.5-3):(0.5-3), preferably 1:(1-2):(1-2); the concentration of mineralized water is 1000-5000ppm, preferably 1000-4000ppm.

[0036] The nonionic surfactant is alkyl polyglycoside (APG), and its molecular structure is as follows:

[0037]

[0038] R1 is C 10 ~C 12 Any of the alkyl groups.

[0039] The sulfate-based anionic surfactant is one or a mixture of two or more of sodium dodecyl sulfate, sodium hexadecyl sulfate, and sodium dodecyl alcohol polyoxyethylene ether sulfate. The sulfonic acid-based anionic surfactant is at least one of sodium dodecyl sulfonate, sodium dodecylbenzene sulfonate, and sodium hexadecyl sulfonate.

[0040] The method for preparing a shale oil reservoir imbibition oil recovery agent comprises the following steps:

[0041] (1) adding a nonionic surfactant alkyl glucoside, a sulfate-based anionic surfactant and a sulfonic acid-based anionic surfactant to mineralized water in proportion to prepare a high-concentration surfactant system;

[0042] (2) The high concentration surfactant is then diluted to a target concentration of 0.01 to 0.4%; the solution is stirred at 40 to 50° C. to completely dissolve it.

[0043] Embodiment 1:

[0044] A nonionic surfactant, decyl glucoside APG10, a sulfate-based anionic surfactant, sodium dodecyl alcohol polyoxyethylene ether sulfate (AES), and a sulfonic acid-based anionic surfactant, sodium dodecyl sulfate (SDS), were selected and added into 2000ppm mineralized water to prepare a surfactant system with a concentration of 0.8%; wherein the mass ratio of APG10, AES, and SDS was 1:0.5:0.5; and then the high-concentration surfactant was diluted to 0.05%, and the solution was stirred at 45°C at a rotation speed of 400rpm for 1h to completely dissolve it, thereby obtaining an imbibition oil displacement agent system.

[0045] Embodiment 2:

[0046] A nonionic surfactant decyl glucoside APG10, a sulfate-based anionic surfactant sodium dodecyl sulfate (SLS) and a sulfonic acid-based anionic surfactant sodium dodecyl sulfate (SDS) were selected and added into 2000ppm mineralized water to prepare a surfactant system with a concentration of 0.8%; wherein the mass ratio of APG10, SLS and SDS was 1:0.5:0.5; and then the high-concentration surfactant was diluted to 0.05%, and the solution was stirred at 45°C and 400rpm for 1h to completely dissolve it, thereby obtaining an imbibition oil-displacing agent system.

[0047] The difference between this embodiment and embodiment 1 is that the sulfate-based anionic surfactant is SLS.

[0048] Embodiment 3:

[0049] A nonionic surfactant decyl glucoside APG10, a sulfate-based anionic surfactant sodium hexadecyl sulfate (SCS) and a sulfonic acid-based anionic surfactant sodium hexadecyl sulfonate (SHS) were selected and added into 2000ppm mineralized water to prepare a surfactant system with a concentration of 0.8%; wherein the mass ratio of APG10, SLS and SDS was 1:0.5:0.5; and then the high-concentration surfactant was diluted to 0.05%, and the solution was stirred at 45°C and 400rpm for 1h to completely dissolve it, thereby obtaining an imbibition oil displacement agent system.

[0050] The difference between this embodiment and embodiment 1 is that the sulfate-based anionic surfactant is SCS and the sulfonic acid-based anionic surfactant is SHS.

[0051] Embodiment 4:

[0052] A nonionic surfactant decyl glucoside APG10, a sulfate-based anionic surfactant sodium dodecyl alcohol polyoxyethylene ether sulfate (AES) and a sulfonic acid-based anionic surfactant sodium dodecyl sulfate (SDS) were selected and added into 2000ppm mineralized water to prepare a surfactant system with a concentration of 0.8%; wherein the mass ratio of APG10, AES and SDS was 1:1:0.5; then the high concentration surfactant was diluted to 0.05%, and the solution was stirred at 45°C at a rotation speed of 400rpm for 1h to completely dissolve it, thereby obtaining an imbibition oil displacement agent system.

[0053] The difference between this embodiment and embodiment 1 is that the mass ratio of APG10, AES and SDS is 1:1:0.5.

[0054] Comparative Example 1:

[0055] A nonionic surfactant, decyl glucoside APG10, was selected and added to 2000ppm mineralized water to prepare a surfactant system with a concentration of 0.8%. The high-concentration surfactant was then diluted to 0.05%, and the solution was stirred at 45°C and 400rpm for 1 hour to completely dissolve it, thereby obtaining a nonionic surfactant system.

[0056] Comparative Example 2:

[0057] A sulfate-based anionic surfactant, sodium dodecyl sulfate (SLS), was selected and added to 2000ppm mineralized water to prepare a surfactant system with a concentration of 0.8%. The high-concentration surfactant was then diluted to 0.05%, and the solution was stirred at 45°C and 400rpm for 1 hour to completely dissolve it, thereby obtaining an anionic surfactant system.

[0058] Performance evaluation of the products obtained in the above examples and comparative examples

[0059] (1) Test on the wettability of shale rock by imbibition oil displacement agent

[0060] The contact angle of the core before and after the imbibition test was measured using the Dataphysics OCA 15Pro device according to the trapped bubble method. In this method, there is usually an oil phase and a water phase, forming a rock-water-oil contact angle. All contact angle values ​​in this study are the angles from the core surface through the water phase to the tangent line of the three-phase junction (such as Figure 1 ). The wettability test results of different surfactant systems are shown in Table 1:

[0061] Table 1

[0062]

[0063] (2) Static absorption test

[0064] Referring to the volumetric method, the sample was subjected to an absorption test. The specific steps are as follows:

[0065] ① Dry the standard core in an oven at 85°C for 24 hours, cool it in a dryer for 0.5 hours, and then measure the dry weight of the core;

[0066] ② Use the method of pressurizing and vacuuming to saturate the simulated oil and calculate the core quality difference before and after saturation with oil;

[0067] ③ Preheat the core and imbibition solution in an oven at 80°C for 1 h;

[0068] ④ Place the core in the infiltration bottle, inject the sample solution into the infiltration bottle, and record the scale of the infiltration solution at this time;

[0069] ⑤Put the permeation bottle in a constant temperature water bath at 80℃ and record the volume of the precipitated oil at regular intervals. Figure 2 shown.

[0070] It can be seen from the experimental results that the samples of Examples 1-4 have better effects than the samples of Comparative Examples 1-2; by comparing Example 3 with Example 1, it can be seen that surfactants with longer carbon chains are more conducive to achieving higher imbibition efficiency; by comparing Example 2 with Example 1, it can be seen that the introduction of ethylene oxide groups can effectively improve the ability of surfactants to change wettability; the composite surfactant system, as a shale imbibition oil displacement agent, can effectively transform shale from oil-wet to water-wet, thereby improving the shale imbibition efficiency by 5-10%.

[0071] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to perform equivalent replacements on parts thereof. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention. Although the above describes the specific implementation methods of the present invention, it is not intended to limit the protection scope of the present invention. Those skilled in the art should understand that, based on the technical solution of the present invention, various modifications or deformations that can be made by those skilled in the art without creative labor are still within the protection scope of the present invention.

Claims

1. A shale oil reservoir imbibition oil recovery agent, characterized in that: The components and proportions thereof are calculated by mass ratio as follows: the mass ratio of nonionic surfactant, sulfate-based anionic surfactant and sulfonic acid-based anionic surfactant is 1:(0.5-3):(0.5-3), the concentration of mineralized water is 1000-5000ppm; the total mass concentration of nonionic surfactant, sulfate-based anionic surfactant and sulfonic acid-based anionic surfactant is 0.5-1%.

2. The shale oil reservoir imbibition oil recovery agent according to claim 1, characterized in that: The nonionic surfactant is alkyl polyglycoside (APG), and its molecular structure is as follows: R1 is C 10 ~C 12 Any of the alkyl groups.

3. The shale oil reservoir imbibition oil recovery agent according to claim 1, characterized in that: The sulfate-based anionic surfactant is one or a mixture of two or more of sodium dodecyl sulfate, sodium hexadecyl sulfate and sodium dodecyl alcohol polyoxyethylene ether sulfate.

4. The shale oil reservoir imbibition oil recovery agent according to claim 1, characterized in that: The sulfonic acid anionic surfactant is at least one of sodium dodecyl sulfonate, sodium dodecylbenzene sulfonate and sodium hexadecyl sulfonate.

5. The shale oil reservoir imbibition oil recovery agent according to claim 1, characterized in that: The total mass concentration of the nonionic surfactant, the sulfate-based anionic surfactant and the sulfonic acid-based anionic surfactant is 0.6-0.8%.

6. The shale oil reservoir imbibition oil recovery agent according to claim 1, characterized in that: The mass ratio of the nonionic surfactant alkyl polyglycoside to the sulfate-based anionic surfactant and the sulfonic acid-based anionic surfactant is 1:(1-2):(1-2).

7. The shale oil reservoir imbibition oil recovery agent according to claim 1, characterized in that: The concentration of the mineralized water is 1000-4000 ppm.

8. A method for preparing a shale oil reservoir imbibition oil recovery agent according to any one of claims 1 to 7, characterized in that: The following steps are involved: (1) adding a nonionic surfactant alkyl glucoside, a sulfate-based anionic surfactant and a sulfonic acid-based anionic surfactant to mineralized water in proportion to prepare a high-concentration surfactant system; (2) The high concentration surfactant is then diluted to the target concentration and the solution is stirred at 40-50°C to completely dissolve it.

9. The preparation method according to claim 8, characterized in that: The target concentration is 0.01-0.4%.

10. Use of the shale oil reservoir imbibition oil recovery agent according to any one of claims 1 to 7 in a fracturing and oil recovery process.

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