An imbibition oil displacement composition and its use

Abstract

The application provides an imbibition oil displacement composition and application thereof, and the imbibition oil displacement composition comprises a surfactant and water, and meets the conditions that the interfacial tension with tight oil is 0.01-10 mN / m and / or the water phase contact angle of the imbibition oil displacement composition when infiltrating a tight core is 15-65°. The interfacial tension between the imbibition oil displacement composition and tight oil still remains in the range of 0.01-10 mN·m ‑1 after aging for 1-7 days at 80 ℃, and the imbibition oil displacement composition plays a role in persistent and stable imbibition replacement in the process of tight reservoir fracturing; under the condition that the permeability is 0.03 mD, the imbibition oil displacement rate of the imbibition oil displacement composition to the tight core is 34%-38%, and the imbibition oil displacement composition has good stability within 120 h, and is suitable for being applied as an imbibition oil displacement agent in imbibition oil displacement of tight oil reservoirs.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of oil and gas field development, and particularly relates to a percolation oil displacement composition and application thereof. BACKGROUND

[0002] The tight oil reservoir generally refers to the oil accumulation under the condition of formation pressure, the matrix permeability is not greater than 0.1 mD (air permeability is less than 1 mD), and the porosity is less than 10%. The tight oil is widely distributed in China, and has large recoverable resources, and is an important oil resource. The most prominent problem exposed in the tight oil exploitation is low single well production, fast production decline, and low recovery. Compared with the conventional oil and gas reservoir, the production decline of the tight oil exploitation is very fast, and the period of natural energy and water injection exploitation is very short. Although the horizontal well and multi-section volume fracturing technology can effectively improve the single well production in the early development stage, the single well production usually decreases to less than 20% of the initial production within one year after the fracturing production, and gradually enters the stable production stage with low decline rate and low production after 9 to 12 months. The rapid decline of the oil well production inevitably leads to the extremely low recovery of the tight oil: the recovery of the tight oil reservoir evaluation volume fracturing development is only 5% to 10% in the first elastic production, and some scholars believe that it can be as low as 1% to 2%, and a large amount of crude oil remains in the ground after the first development. Even if the secondary water injection development is carried out, due to the influence of channeling, the tight oil enhanced recovery often does not work or has little effect. Therefore, for the tight oil reservoir, the development of the tight oil reservoir is the only way to greatly improve the recovery.

[0003] Due to the tight reservoir, the injected water is often difficult to directly enter the tight matrix and displace the crude oil, and mainly flows in the fracturing or natural fracture, so the fluid replacement between the water phase in the fracture and the tight matrix crude oil based on the "percolation effect" becomes the key to improve the recovery of the tight oil reservoir. In the water injection development of the traditional low permeability reservoir (permeability is less than 50 mD), people also emphasize the percolation oil displacement mechanism of the water phase, carry out more researches on the surfactant assisted enhanced water phase percolation effect, and obtain some efficient percolation systems. However, compared with the traditional reservoir, the tight oil reservoir (permeability is less than 0.1 mD) is more tight, the permeability is lower, and the main driving force of percolation is obviously changed compared with the traditional low permeability reservoir, which is significantly different, which leads to the fact that some existing percolation systems are not ideal for the percolation oil displacement effect of the tight oil reservoir: 1. The percolation effect of the percolation system with ultra-low interfacial tension is significantly weakened, and even lower than the percolation efficiency of the simulated water alone; 2. The nano particle percolation system is easy to form micron aggregates in the nano scale tight reservoir pore throat, which restricts the percolation of the tight matrix; 3. The carbon dioxide produced by the decomposition of the chemical substance provides the displacement energy for the oil and gas migration, and there are problems of unsatisfactory replacement effect, large amount of use, and difficult storage and transportation in the actual application process. Therefore, it is urgent to develop a more efficient percolation oil displacement system suitable for the tight oil reservoir. SUMMARY

[0004] In view of the problem that the oil absorption effect is not ideal when the existing imbibition oil displacement system is applied to the tight oil reservoir, the present application aims to provide an imbibition oil displacement composition which is a high-efficiency imbibition oil displacement agent suitable for tight oil reservoirs.

[0005] The present application provides an imbibition oil displacement composition comprising a surfactant and water.

[0006] The interfacial tension between the imbibition oil displacement composition and the tight oil is 0.01 to 10 mN / m; and / or the water phase contact angle of the imbibition oil displacement composition wetting the tight core is 15° to 65°.

[0007] According to one specific embodiment of the present application, the interfacial tension between the imbibition oil displacement composition and the tight oil is 0.01 to 1 mN / m; and / or the water phase contact angle of the imbibition oil displacement composition wetting the tight core is 20° to 65°.

[0008] In the present application, the tight oil refers to the oil resources in the shale pores and fractures and the adjacent and interbedded tight carbonate rocks or clastic rocks in the shale series, and the formation has the characteristics of developing nanoscale pore throats and microfractures, a porosity of less than 10%, and an extremely low permeability, with a matrix permeability of not greater than 0.1 mD and an air permeability of less than 1 mD.

[0009] According to one specific embodiment of the present application, the surfactant comprises an anionic surfactant and a zwitterionic surfactant.

[0010] According to one specific embodiment of the present application, the surfactant further comprises a nonionic surfactant.

[0011] According to one specific embodiment of the present application, the surfactant comprises 50wt% to 75wt% of the anionic surfactant, 25wt% to 50wt% of the zwitterionic surfactant, and 0 to 10wt% of the nonionic surfactant, based on 100% of the mass of the surfactant.

[0012] According to one specific embodiment of the present application, the imbibition oil displacement composition further comprises a cosolvent.

[0013] Preferably, the cosolvent is a lower alcohol.

[0014] Preferably, the lower alcohol is ethanol and / or isopropyl alcohol.

[0015] According to one specific embodiment of the present application, the wicking oil displacement composition comprises 0.1 wt% to 0.5 wt% of the surfactant, 99.5 wt% to 99.9 wt% of water and the balance of the co-solvent, based on 100% by mass of the wicking oil displacement composition.

[0016] According to one specific embodiment of the present application, the wicking oil displacement composition comprises 0.1 wt% to 0.3 wt% of the surfactant, 0 to 0.1 wt% of the co-solvent and 99.7 wt% of water, based on 100% by mass of the wicking oil displacement composition.

[0017] Preferably, the surfactant comprises 50 wt% to 75 wt% of the anionic surfactant and 25 wt% to 50 wt% of the zwitterionic surfactant, based on 100% by mass of the surfactant.

[0018] According to one specific embodiment of the present application, the anionic surfactant is selected from at least one of fatty alcohol polyoxyethylene ether sulfate, dodecyl benzene sulfonate and petroleum sulfonate;

[0019] Preferably, the fatty alcohol polyoxyethylene ether is sodium dodecanol polyoxyethylene ether sulfate (AES); and / or

[0020] the dodecyl benzene sulfonate is sodium dodecyl benzene sulfonate (SDBS); and / or

[0021] the petroleum sulfonate is sodium petroleum sulfonate.

[0022] According to one specific embodiment of the present application, the zwitterionic surfactant is selected from dodecyl dimethyl betaine (BS-12) and / or erucyl amido hydroxypropyl sulfonate betaine (EHSB).

[0023] According to one specific embodiment of the present application, the non-ionic surfactant is selected from at least one of octyl phenyl polyoxyethylene ether (TX-100), octyldecyl glucoside (APG0810) and coco diethanolamide (6051).

[0024] According to one specific embodiment of the present application, the water is formation simulated water.

[0025] Preferably, the formation simulated water is 0.02 wt% KCl aqueous solution.

[0026] According to one specific embodiment of the present application, the wicking oil displacement composition is prepared by the following method:

[0027] The surfactant and water are mixed and stirred at a first rotating speed to obtain the wicking oil displacement composition.

[0028] Preferably, the surfactant and the co-solvent are mixed first, stirred at the second rotation speed, and then mixed with the water;

[0029] Preferably, the first rotation speed is 350 rpm; and / or

[0030] The second rotation speed is 300 rpm to 600 rpm.

[0031] The application of the imbibition oil displacement composition according to the present application in tight oil reservoir oil production, in particular in tight oil reservoir imbibition oil displacement.

[0032] The present application has the following beneficial effects:

[0033] The present application provides an imbibition oil displacement composition and its application, the imbibition oil displacement composition comprising a surfactant and water; the interfacial tension between the imbibition oil displacement composition and tight oil is 0.01 to 10 mN / m; and / or the water phase contact angle of the imbibition oil displacement composition infiltrated tight core is 15° to 65°. It is determined that the interfacial tension between the imbibition oil displacement composition provided by the present application and tight oil is 0.02 to 0.93 mN / m, the water phase contact angle of the tight core infiltrated by the imbibition oil displacement composition is 20° to 64.8°, the interfacial tension is in the range of 0.01 to 10 mN / m, and the water phase contact angle is in the range of 15° to 65°; the imbibition oil displacement composition can still keep the interfacial tension with tight oil in the range of 0.01 to 10 mN·m -1 After aging at 80℃ for 1 to 7 days, which helps it to play a persistent and stable imbibition displacement role in the process of tight reservoir fracturing; under the condition of permeability of 0.03 mD, the imbibition oil displacement efficiency of the imbibition oil displacement composition on tight core is 34% to 38%, and it has good stability within 120h, which is about 30% higher than the imbibition oil displacement efficiency of the control group simulated water, and is suitable for application as an imbibition oil displacement agent in tight oil reservoir imbibition oil displacement. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 The imbibition oil displacement results of the imbibition oil displacement compositions and simulated water prepared for Examples 1 to 4 on cores with permeability of 0.03 mD at 80℃;

[0035] Figure 2 The imbibition oil displacement results of the imbibition oil displacement compositions and simulated water prepared for Examples 5 to 8 on cores with permeability of 0.03 mD at 80℃;

[0036] Figure 3 The imbibition oil displacement results of the imbibition oil displacement compositions and simulated water prepared for Examples 2, Example 7, Comparative Example 1 and Comparative Example 2 on cores with permeability of 0.03 mD at 80℃;

[0037] Figure 4 The imbibition oil displacement results of the imbibition oil displacement composition in Comparative Example 3 and Comparative Example 4 and simulated water on a core with a permeability of 0.03 mD at 80°C. DETAILED DESCRIPTION

[0038] The application will be further described in conjunction with the examples. However, the examples are only illustrative and do not limit the application in any way.

[0039] The sodium dodecanol polyoxyethylene ether sulfate used in Examples 1 to 4 and Comparative Example 1 is purchased from Haian Petrochemical Factory in Jiangsu Province, and its structural formula is shown in Formula I:

[0040]

[0041] wherein R is C 12 alkyl, and n is an integer of 5 to 20.

[0042] The sodium dodecanol polyoxyethylene ether sulfate used in Examples 1 to 4 and Comparative Example 1 is purchased from Haian Petrochemical Factory in Jiangsu Province, and its structural formula is shown in Formula I:

[0043]

[0044] The erucic acid amide hydroxypropyl sulfobetaine used in Examples 1 to 8 and Comparative Examples 1 and 2 has a structural formula as shown in Formula III:

[0045]

[0046] The coconut diethanolamide used in Comparative Examples 1 and 2 has a structural formula as shown in Formula IV:

[0047]

[0048] wherein R1 is a coconut group.

[0049] Example 1

[0050] The sodium dodecanol polyoxyethylene ether sulfate and the erucic acid amide hydroxypropyl sulfobetaine are mixed at a mass ratio of 5:3, stirred at a speed of 600 rpm until mixed uniformly, and then further mixed with a KCl aqueous solution with a KCl mass fraction of 0.02 wt%, stirred at a speed of 350 rpm until mixed uniformly, to obtain an imbibition oil displacement composition; wherein the total mass of the sodium dodecanol polyoxyethylene ether sulfate and the erucic acid amide hydroxypropyl sulfobetaine accounts for 0.3 wt% of the mass of the 0.02 wt% KCl aqueous solution.

[0051] Example 2

[0052] Sodium dodecylbenzenesulfonate and erucylamidehydroxypropyl sulfobetaine are mixed according to a mass ratio of 3:1, stirred at a speed of 600 rpm until mixed uniformly, and then further mixed with a KCl aqueous solution with a KCl mass fraction of 0.02wt% and stirred uniformly at a speed of 350 rpm to obtain the wicking oil displacement composition; wherein the total mass of sodium dodecylbenzenesulfonate and erucylamidehydroxypropyl sulfobetaine accounts for 0.3wt% of the mass of the 0.02wt% KCl aqueous solution.

[0053] Example 3

[0054] Sodium dodecylbenzenesulfonate, erucylamidehydroxypropyl sulfobetaine and isopropyl alcohol are mixed according to a mass ratio of 3:1:2, stirred uniformly at a speed of 600 rpm, and then further mixed with a KCl aqueous solution with a KCl mass fraction of 0.02wt% and stirred uniformly at a speed of 350 rpm to obtain the wicking oil displacement composition; wherein the total mass of sodium dodecylbenzenesulfonate, erucylamidehydroxypropyl sulfobetaine and isopropyl alcohol accounts for 0.3wt% of the mass of the 0.02wt% KCl aqueous solution.

[0055] Example 4

[0056] Sodium dodecylbenzenesulfonate, erucylamidehydroxypropyl sulfobetaine and isopropyl alcohol are mixed according to a mass ratio of 5:3:4, stirred uniformly at a speed of 600 rpm, and then further mixed with a KCl aqueous solution with a KCl mass fraction of 0.02wt% and stirred uniformly at a speed of 350 rpm to obtain the wicking oil displacement composition; wherein the total mass of sodium dodecylbenzenesulfonate, erucylamidehydroxypropyl sulfobetaine and isopropyl alcohol accounts for 0.3wt% of the mass of the 0.02wt% KCl aqueous solution.

[0057] Example 5

[0058] Sodium dodecylbenzenesulfonate and erucylamidehydroxypropyl sulfobetaine are mixed according to a mass ratio of 3:1, stirred uniformly at a speed of 600 rpm, and then further mixed with a KCl aqueous solution with a KCl mass fraction of 0.02wt% and stirred uniformly at a speed of 350 rpm to obtain the wicking oil displacement composition; wherein the total mass of sodium dodecylbenzenesulfonate and erucylamidehydroxypropyl sulfobetaine accounts for 0.3wt% of the mass of the 0.02wt% KCl aqueous solution.

[0059] Example 6

[0060] Sodium dodecyl benzene sulfonate and erucylamide MEA-sulfosuccinate were mixed in a mass ratio of 1:1, stirred uniformly at a rotating speed of 600 rpm, and then further mixed with a KCl aqueous solution with a KCl mass fraction of 0.02 wt%, stirred uniformly at a rotating speed of 350 rpm, to obtain a wicking oil displacement composition; wherein the total mass of sodium dodecyl benzene sulfonate and erucylamide MEA-sulfosuccinate accounted for 0.3 wt% of the mass of the 0.02 wt% KCl aqueous solution.

[0061] Example 7

[0062] Sodium dodecyl benzene sulfonate, erucylamide MEA-sulfosuccinate, and isopropyl alcohol were mixed in a mass ratio of 5:3:4, stirred uniformly at a rotating speed of 600 rpm, and then further mixed with a KCl aqueous solution with a KCl mass fraction of 0.02 wt%, stirred uniformly at a rotating speed of 350 rpm, to obtain a wicking oil displacement composition; wherein the total mass of sodium dodecyl benzene sulfonate, erucylamide MEA-sulfosuccinate, and isopropyl alcohol accounted for 0.3 wt% of the mass of the 0.02 wt% KCl aqueous solution.

[0063] Example 8

[0064] Sodium dodecyl benzene sulfonate, erucylamide MEA-sulfosuccinate, and isopropyl alcohol were mixed in a mass ratio of 1:1:1, stirred uniformly at a rotating speed of 600 rpm, and then further mixed with a KCl aqueous solution with a KCl mass fraction of 0.02 wt%, stirred uniformly at a rotating speed of 350 rpm, to obtain a wicking oil displacement composition; wherein the total mass of sodium dodecyl benzene sulfonate, erucylamide MEA-sulfosuccinate, and isopropyl alcohol accounted for 0.3 wt% of the mass of the 0.02 wt% KCl aqueous solution.

[0065] Comparative Example 1

[0066] Sodium dodecyl benzene sulfonate, erucylamide MEA-sulfosuccinate, and isopropyl alcohol were mixed in a mass ratio of 1:1:1, stirred uniformly at a rotating speed of 600 rpm, and then further mixed with a KCl aqueous solution with a KCl mass fraction of 0.02 wt%, stirred uniformly at a rotating speed of 350 rpm, to obtain a wicking oil displacement composition; wherein the total mass of sodium dodecyl benzene sulfonate, erucylamide MEA-sulfosuccinate, and isopropyl alcohol accounted for 0.3 wt% of the mass of the 0.02 wt% KCl aqueous solution.

[0067] Comparative Example 2

[0068] Sodium dodecyl benzene sulfonate, erucylamide propylsulfobetaine and cocodiethanolamide were mixed in a mass ratio of 1:1:1, stirred uniformly at a speed of 600 rpm, and then further mixed with a KCl aqueous solution with a KCl mass fraction of 0.02wt%, stirred uniformly at a speed of 350 rpm, to obtain the wicking oil displacement composition; wherein the total mass of sodium dodecyl benzene sulfonate, erucylamide propylsulfobetaine and cocodiethanolamide accounted for 0.3wt% of the mass of the 0.02wt% KCl aqueous solution.

[0069] Comparative Example 3

[0070] Cetyltrimethylammonium bromide (CTAB) and a KCl aqueous solution with a KCl mass fraction of 0.02wt% were mixed and stirred uniformly at a speed of 350 rpm to obtain the wicking oil displacement composition; wherein the mass of cetyltrimethylammonium bromide accounted for 0.3wt% of the mass of the 0.02wt% KCl aqueous solution.

[0071] Comparative Example 4

[0072] Dodecyltrimethylammonium chloride (DTAC) and a KCl aqueous solution with a KCl mass fraction of 0.02wt% were mixed and stirred uniformly at a speed of 350 rpm to obtain the wicking oil displacement composition; wherein the mass of dodecyltrimethylammonium chloride accounted for 0.3wt% of the mass of the 0.02wt% KCl aqueous solution.

[0073] Experimental evaluation

[0074] The tight oil used in the following experiments: tight oil of a certain block (density of 0.8g / cm 3 , viscosity of 2.7mPa.s) under the condition of underground temperature of 80℃;

[0075] The tight core used in the following experiments: average permeability of 0.03×10 -3 μm 2 , diameter of 2.5cm, average length of 3cm.

[0076] a. Measurement of interfacial tension between wicking oil displacement composition and tight oil

[0077] The interfacial tension between the imbibition oil displacement composition prepared in Examples 1 to 8 and Comparative Examples 1 and 2 and the tight oil was determined at 80°C by the rotating drop method according to the petroleum and natural gas industry standard SY / T5370-2018 "Determination method of surface and interfacial tension", and the interfacial tension between the imbibition oil displacement composition prepared in each of the examples and the comparative examples and the tight oil was determined for three times in succession, and the arithmetic mean value was taken as the determination result; the simulated water (specifically, a 0.02wt% KCl aqueous solution) was used as a control group, and the interfacial tension between the simulated water and the tight oil was determined for three times in succession, and the arithmetic mean value was taken as the determination result, and the specific results are shown in Table 1.

[0078] b. Measurement of water phase contact angle of the core after imbibition of the imbibition oil displacement composition

[0079] (1) Preparation of the core saturated with oil and aged: the tight core was saturated with tight oil using a core vacuum pressurization saturation experimental device, and was aged in an oven at 80°C for 14 days to obtain the core saturated with oil and aged;

[0080] (2) Simulated water: a 0.02wt% KCl aqueous solution;

[0081] (3) The water phase contact angle of the core saturated with oil and aged was measured according to the contact angle method in the petroleum industry standard SY / T5153-2017 "Determination method of reservoir rock wettability" and was recorded to determine the initial wettability thereof;

[0082] (4) The core saturated with oil and aged was immersed in the imbibition oil displacement composition at 80°C for imbibition, and the water phase contact angle of the surface of the core was determined again according to the same method as in step (3) and was recorded;

[0083] According to the method described in steps (3) and (4) above, the water phase contact angle of the core before and after imbibition of the imbibition oil displacement composition prepared in Examples 1 to 8 and Comparative Examples 1 and 2 was determined, and the simulated water used for testing was the 0.02wt% KCl aqueous solution in step (2). One core was used for each imbibition oil displacement composition prepared in each example to perform the experiment, and the specific results are shown in Table 1. According to the method described in steps (3) and (4), the imbibition oil displacement composition was replaced with the simulated water, and one core was used alone to determine the water phase contact angle of the core before and after imbibition of the simulated water as a control group, and the results are shown in Table 1. According to the experiment, the average value of the water phase initial contact angle of the 11 cores saturated with oil and aged used in Examples 1 to 8, Comparative Examples 1 and 2 and the control group was 117.2°.

[0084] Table 1. Interfacial tension between the imbibition oil displacement composition and the tight oil and water phase contact angle of the core after imbibition of the imbibition oil displacement composition

[0085]

[0086] The initial water phase contact angle of the core saturated with the oil and aged is 117.2°, which indicates that the initial wettability of the tight core saturated with the oil and aged is oil-wet. As shown in Table 1, the interfacial tension between the imbibition oil displacement composition prepared in Examples 1 to 8 and the tight oil is 0.02 to 0.93 mN·m -1 , in the range of 0.01 to 10 mN / m; the water phase contact angle of the core after imbibition is 20.9° to 64.8°, in the range of 15° to 65°. The interfacial tension between the imbibition oil displacement composition prepared in Comparative Example 1 and Comparative Example 2 and the tight oil is 0.001 to 0.005 mN·m -1 , which is far lower than the lower limit value of the interfacial tension range of 0.01 to 10 mN / m -1 ; the interfacial tension between the simulated water of the control group and the tight oil is 15.17 mN·m -1 , which is higher than the upper limit value of the interfacial tension range of 0.01 to 10 mN / m -1 ; the water phase contact angle of the core after imbibition of the imbibition oil displacement composition prepared in Comparative Example 1 is 70.6°, which is higher than the upper limit value of the range of 15° to 65°; the water phase contact angle of the core after imbibition of the simulated water of the control group is 89.0°, which is obviously higher than the upper limit value of the range of 15° to 65°.

[0087] 2. Temperature resistance determination of imbibition oil displacement composition

[0088] According to the rotating drop method specified in the Petroleum and Natural Gas Industry Standard SY / T5370-2018 "Method for Determining Surface and Interfacial Tension", the interfacial tension between the aged imbibition oil displacement composition and the tight oil was determined with the tight oil as the low-density phase. The specific steps are as follows:

[0089] 200 g of the imbibition oil displacement composition prepared in Example 2 and Example 7 was weighed and sealed, and then placed in an oven at 80℃ for aging. When the aging time was 1 day, 2 days, 3 days and 7 days, the interfacial tension between the imbibition oil displacement composition prepared in Example 2 and Example 7 and the tight oil was determined at 80℃ according to the rotating drop method specified in the Petroleum and Natural Gas Industry Standard SY / T5370-2018 "Method for Determining Surface and Interfacial Tension", with the tight oil as the low-density phase. The results are shown in Table 2.

[0090] Table 2. Interfacial tension between the imbibition oil displacement composition prepared in Example 2 and Example 7 and the tight oil after different aging time at 80℃

[0091]

[0092] As can be seen from the data in Table 2, the wicking oil displacement compositions prepared in Example 2 and Example 7 can still maintain the interfacial tension at 0.18 to 0.72 mN·m after aging at 80℃ for 1 to 7 days -1 , which is helpful for its long-lasting and stable wicking displacement in the process of fracturing in tight reservoirs.

[0093] 3. Wicking efficiency determination of wicking oil displacement composition

[0094] ⅰ Measurement of permeability using core displacement device: using core vacuum pressurized saturation experimental device, saturate the tight core with tight oil, and age in the oven at 80℃ for 14 days to obtain the saturated oil and the core after aging, and calculate the initial oil content after taking out;

[0095] ⅱ Spontaneous wicking experiment by volume method using Amott wicking bottle: first, preheat the wicking composition to 80℃, then put the tight core saturated with oil and aged in step i into the Amott wicking bottle with a precision of 0.01 mL, then inject 300 mL of preheated wicking oil displacement composition into the bottle to immerse the tight core, then place the Amott wicking bottle in a constant temperature water bath device at 80℃, and record the volume of tight oil floating into the measuring tube of the wicking bottle every time a counting point is reached. When the volume of tight oil in the measuring tube does not change continuously for 24 h, the experiment is ended; calculate the wicking oil displacement efficiency at different time points.

[0096] The wicking oil displacement compositions prepared in Examples 1 to 8 and Comparative Examples 1 to 4 were subjected to spontaneous wicking experiments according to the above method, with simulated water (i.e. 0.02wt% KCl aqueous solution) as the control group. The measured wicking oil displacement rates at different experimental times were plotted into wicking oil displacement rate-experimental time curve, as shown in Figures 1 to 4 , wherein the wicking oil displacement efficiency of the control group simulated water is only about 8% at most within 120 h, and the cases of Examples 1 to 8 and Comparative Examples 1 to 4 are as follows.

[0097] Figure 1 The wicking oil displacement rate-experimental time curve of the wicking oil displacement compositions prepared in Examples 1 to 4 and simulated water at 80℃ is shown. Figure 1The curves show that within the first 10 hours of the experiment, the permeation efficiency of the four permeation-drainage compositions increased at almost the same rapid rate to around 31%. Then, the permeation efficiency of the permeation-drainage composition prepared in Example 2 increased at a slightly slower rate to 38% and remained stable for 120 hours; the permeation efficiency of the permeation-drainage composition prepared in Example 1 increased at a slightly slower rate to 36% and remained stable for 120 hours; the permeation efficiency of the permeation-drainage compositions prepared in Examples 3 and 4 increased to around 33% within the 120-hour experimental period and remained stable. It is evident that the permeation-drainage compositions prepared in Examples 1 to 4 can achieve stable and efficient permeation into dense cores.

[0098] Figure 2 The diagram shows the oil-permeation and drainage compositions prepared in Examples 5 to 8, and the oil-permeation and drainage rate-experimental time curves of simulated water at 80°C. Figure 2 As can be seen, within the experimental period of 0 to 120 hours, the oil absorption and drainage rates of the oil absorption and drainage compositions prepared in Examples 5 to 8 increased rapidly in the short period after the start of the experiment and stabilized in the range of 34% to 38%. This indicates that the oil absorption and drainage compositions prepared in Examples 5 to 8 have good oil absorption and drainage effects and good stability.

[0099] Figure 3 The diagram shows the oil permeation and drainage compositions prepared in Examples 2, 7, Comparative Example 1, and Comparative Example 2, and the oil permeation and drainage rate-experimental time curves of simulated water at 80°C. From... Figure 3 As can be seen, under 80℃ conditions, the oil drainage compositions prepared in Examples 2 and 7 rapidly increased their oil drainage rate to 37% within 0 to 20 hours of the experiment, and then slowly increased to 38% within 30 to 120 hours before stabilizing, achieving efficient oil drainage of dense cores. The oil drainage efficiency of the oil drainage composition prepared in Comparative Example 1 slowly increased to 13% after 85 hours of testing, with a significantly lower drainage efficiency. The drainage efficiency of the oil drainage composition prepared in Comparative Example 2 increased slowly to 21% after 100 hours of testing. Although the drainage efficiency was higher than that of Comparative Example 1, it was still significantly lower than that of Examples 2 and 7.

[0100] Figure 4 The graphs showing the oil permeation and drainage compositions prepared in Comparative Examples 3 and 4, and simulated water, are presented as experimental time curves illustrating the oil permeation and drainage rate. Figure 4 It can be clearly observed that, under 80℃ conditions, the permeation and drainage rates of the permeation and drainage compositions prepared in Comparative Examples 3 and 4 are between 0% and 1%, even lower than the permeation and drainage rate of the simulated water in the control group. This indicates that the permeation and drainage compositions prepared in Comparative Examples 3 and 4 have poor permeation and drainage effects on tight cores and are not suitable for tight oil reservoirs.

[0101] Based on the analysis of Table 1, Table 2, Figures 1 to 4 The interfacial tension between the wicking oil displacement composition prepared in Examples 1 to 8 and the tight oil is 0.02 to 0.93 mN·m -1 in the range of 0.01 to 10 mNm -1 ; the water phase contact angle of the core after wicking is 20.9° to 64.8° in the range of 15° to 65°; the wicking oil displacement rate on the tight core reaches 34% to 38%, and has good stability within 120 h; and in Examples 1 to 8, the wicking oil displacement rates of Example 2 and Example 7 are the highest, both reaching 38%, but the interfacial tension between the two and the tight oil is not the lowest, but remains at the order of 10 -1 mNm -1 ; and the interfacial tension between the wicking oil displacement composition prepared in Comparative Example 1 and Comparative Example 2 and the tight oil reaches 10 -3 mNm -1 ultra-low interfacial tension, but the wicking oil displacement rates of the two are only 12% to 21% in turn, which is much lower than the wicking oil displacement composition prepared in Examples 1 to 8. The experimental results of Examples 1 to 8, Comparative Example 1 and Comparative Example 2 can show that the ultra-low interfacial tension of 10 -3 mNm -1 is not a sufficient condition to achieve efficient wicking of tight oil. When the interfacial tension is too high, the adhesion work increases, and the tight oil replacement is relatively difficult. When the interfacial tension is too low, the capillary force is weakened, and the wicking oil displacement efficiency is not ideal. The wicking oil displacement composition provided by the present application is suitable for wicking oil displacement operation of tight oil reservoirs.

[0102] Although the present application has been described with reference to specific embodiments, it is understood by those skilled in the art that various changes can be made without departing from the true spirit and scope of the present application. In addition, various changes can be made to the subject matter, spirit and scope of the present application to adapt to specific situations, materials, material compositions and methods. All these changes are included in the scope of the claims of the present application.

Claims

1. An oil-absorbing composition comprising a surfactant and water; The surfactant is composed of anionic surfactants and amphoteric surfactants, wherein, The anionic surfactant is sodium dodecyl polyoxyethylene ether sulfate or sodium dodecylbenzene sulfonate, and the amphoteric surfactant is erucamide hydroxypropyl sulfobetaine. The interfacial tension between the percolating and draining composition and the tight oil is 0.01 to 10 mN / m; and / or the aqueous contact angle of the percolating and draining composition in wetting the tight core is 15° to 65°.

2. The oil-absorbing and draining composition according to claim 1, characterized in that, The surfactant is 100% by mass, and the surfactant comprises 50 wt% to 75 wt% of the anionic surfactant and 25 wt% to 50 wt% of the amphoteric surfactant.

3. An oil-absorbing composition comprising a surfactant, water, and a co-solvent; The surfactant is composed of anionic surfactants and amphoteric surfactants, wherein, The anionic surfactant is sodium dodecyl polyoxyethylene ether sulfate or sodium dodecylbenzene sulfonate, and the amphoteric surfactant is erucamide hydroxypropyl sulfobetaine. The co-solvent is a lower alcohol; The interfacial tension between the percolating and draining composition and the tight oil is 0.01 to 10 mN / m; and / or the aqueous contact angle of the percolating and draining composition in wetting the tight core is 15° to 65°.

4. The oil-absorbing and draining composition according to claim 3, characterized in that, The permeation and oil-removing composition is 100% by weight, comprising 0.1 wt% to 0.5 wt% of the surfactant, 99.5 wt% to 99.9 wt% of water, and the balance being the co-solvent.

5. The oil-absorbing and draining composition according to claim 3, characterized in that, The surfactant is 100% by mass, and the surfactant comprises 50 wt% to 75 wt% of the anionic surfactant and 25 wt% to 50 wt% of the amphoteric surfactant.

6. The application of the percolation and drainage composition according to any one of claims 1 to 5 in the production of oil from tight reservoirs.

7. The use of the percolation drainage composition according to any one of claims 1 to 5 in percolation drainage of tight oil reservoirs.

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