Reverse wetting agent as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of oil and gas field exploitation, and particularly relates to a reverse wetting agent and a preparation method and application thereof. The reverse wetting agent is prepared from the following raw materials in percentage by weight: 40 to 45 percent of Gemini surfactant solution, 45 to 50 percent of chelating agent solution and the balance of water. The reverse wetting agent is suitable for high-temperature high-salt low-permeability / tight oil reservoirs, the degree of mineralization of water for preparation is 5 * 10 < 4 > mg / L-10 * 10 < 4 > mg / L, calcium and magnesium ions are smaller than or equal to 1000 mg / L, the temperature is smaller than or equal to 95 DEG C, and the permeability is smaller than or equal to 10 mD; and good imbibition efficiency is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas field development, and in particular relates to a wettability reversal agent and a preparation method and application thereof. Background Art

[0002] China's low-permeability / tight oil is widely distributed and has huge recoverable resources. It is the most important oil successor resource in the future. The most prominent problems exposed in the exploitation of low-permeability / tight oil are: low single-well production, rapid production decline, and low recovery rate. Compared with conventional oil and gas reservoirs, the production decline of low-permeability / tight oil exploitation is very fast, and the cycle of exploitation using natural energy and water injection is very short. Although the use of horizontal wells, multi-stage volume fracturing and other technologies can effectively increase the single-well production in the early stage of development, after fracturing is put into production, the single-well production usually drops to less than 20% of the initial production within one year, and gradually enters a stable production stage with low decline rate and low production after 9-12 months. The rapid decline in oil well production will inevitably lead to extremely low recovery rate of low-permeability / tight oil: the recovery rate of the first elastic exploitation of foreign low-permeability / tight oil reservoir evaluation volume fracturing development is only 5%-10%, and some scholars believe that it can even be as low as 1%-2%. After the first development, there is still a huge amount of crude oil left underground. Even if secondary water injection is carried out, due to the influence of crossflow, the recovery rate of low permeability / tight oil is ineffective or has little effect. Therefore, significantly improving the recovery rate of low permeability / tight oil reservoirs is the only way to develop.

[0003] Due to the dense reservoir, it is often difficult for injected water to directly enter the low permeability / tight matrix and displace crude oil, but it mainly flows in fracturing or natural fractures. In this way, the fluid replacement between the water phase in the fracture and the low permeability / tight matrix crude oil based on the "imbibition effect" becomes the key to improving the recovery of low permeability / tight oil. In the traditional water injection development of medium / high permeability oil reservoirs, people also emphasize the imbibition and oil discharge mechanism of the water phase, and have carried out a lot of research on surfactant-assisted enhancement of the water phase imbibition effect, and obtained some high-efficiency imbibition systems. However, for the low permeability / tight oil reservoir range, it is more dense and has lower permeability. The main driving force of imbibition has undergone a significant change compared with the traditional medium / high permeability oil reservoir, and there are significant differences. This has led to some existing imbibition systems cannot be directly used to improve the recovery of low permeability / tight oil reservoirs. At the same time, general surfactant systems are no longer suitable for high temperature and high salt conditions.

[0004] Chinese invention patent application CN201911011026.5 discloses a biological wettability reversal agent for high-temperature and high-salinity heavy oil reservoirs, whose composition and components are as follows: 20-30wt% rhamnolipid fermentation broth; 15-20wt% sophorolipid fermentation broth; 3-5wt% alkyl polyglycosides; 0.1-0.3wt% alcohol adjuvant; water balance; suitable for heavy oil reservoirs with reservoir temperatures greater than 80°C and mineralization greater than 30,000 mg / L, especially for oil wells with a comprehensive water content of more than 95% after multiple rounds of cold production, but its adaptability to low-permeability / tight reservoirs with a higher mineralization of 100,000 mg / L is unclear.

[0005] Chinese invention patent application CN110467912A discloses a high-temperature triggered wettability reversal agent and its preparation method and application. The wettability reversal agent is protected by the reaction of phthalic anhydride and primary amine to generate phthalimide, and a high-temperature triggered wettability reversal agent is obtained by reacting alkane bromide with secondary amine to combine long-chain alkyl with amino group. Under the high temperature of oil and gas layer, it is transformed into an anionic surfactant carrying multiple carboxyl groups, and forms a mixed adsorption layer with the polar substances originally adsorbed on the surface at the reversal layer to produce an emulsification effect, thereby changing the wettability of the rock wall to a certain extent, thereby improving the final recovery rate. However, it is only suitable for high-temperature reservoirs, and its adaptability to high-mineralization low-permeability / tight reservoirs is unclear.

[0006] Chinese invention patent application CN106634894A provides a dicationic fluorocarbon surfactant used as a wettability reversal agent in oil and gas drilling, which makes the rock have hydrophobic and oleophobic properties. It is a double-repellent treatment agent that achieves hydrophobic and oleophobic properties on the rock surface. Especially when drilling shale that is easy to be hydrated, it can effectively prevent the entry of water and oil, prevent the occurrence of capillary phenomena, and achieve the effect of stabilizing the well wall and protecting the reservoir. However, it is only suitable for oil and gas drilling, and cannot be used to improve the recovery rate of high-temperature, high-mineralization, low-permeability / tight oil reservoirs. Summary of the invention

[0007] In view of the lack of wettability reversal agents under high-temperature and high-salinity reservoir conditions, the present invention provides a wettability reversal agent and its preparation method and application. The present invention combines a highly active Gemini surfactant with a chelating agent to establish a preparation method for a high-temperature, high-mineralization, low-permeability / tight oil reservoir wettability reversal agent, constructs a wettability reversal imbibition system, and solves the key problem of the lack of wettability reversal agents under low-permeability, high-temperature, and high-salinity oil reservoir conditions. The system effectively changes the wettability of high-temperature, high-mineralization, low-permeability / tight oil reservoirs, achieves the purpose of efficient imbibition and oil drainage, and thus improves the recovery rate of low-permeability / tight oil reservoirs.

[0008] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0009] A wettability reversal agent, characterized in that the raw materials of the wettability reversal agent include Gemini surfactant solution, chelating agent solution and water.

[0010] Preferably, in terms of weight percentage, the raw materials of the wettability reversal agent include 40%-45% of Gemini surfactant solution, 45%-50% of chelating agent solution and the balance of water.

[0011] Preferably, the mass concentration of the Gemini surfactant solution is 40%-60%.

[0012] Preferably, the mass concentration of the chelating agent solution is 50%-70%.

[0013] Preferably, the Gemini surfactant is a diquaternary ammonium salt surfactant, and the molecular formula structure of the diquaternary ammonium salt surfactant is as follows:

[0014]

[0015] Among them, n is 8-12.

[0016] Preferably, the chelating agent is selected from one or both of hydroxyethylidene diphosphonic acid and aminotrimethylene phosphonic acid, and the structural formula thereof is as follows:

[0017]

[0018] The present invention also relates to a method for preparing the wettability reversal agent, comprising the following steps:

[0019] (1) Adding the Gemini surfactant solution into water and stirring to obtain solution A;

[0020] (2) Add the chelating agent solution into solution A and stir to obtain a wettability reversal agent.

[0021] Preferably, the stirring speed in step (1) and step (2) is 300-600 rpm, the stirring time is 10-20 min, and the stirring temperature is 20-30°C.

[0022] The present invention also relates to the application of the wettability reversal agent in oil and gas drilling.

[0023] Preferably, the wettability reversal agent is used in an amount of 0.1-0.5 parts by weight relative to 100 parts by weight of water in the water-based drilling fluid.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The wettability reversal agent of the present invention is suitable for high-temperature, high-salinity, low-permeability / tight oil reservoirs. The salinity of the water used for preparation is 5×104 mg / L-10×10 4 mg / L, calcium and magnesium ions ≤1000mg / L, temperature ≤95℃, permeability ≤10mD;

[0026] (2) The wettability reversal agent of the present invention has a good absorption efficiency of 30.0%-40.0%. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present invention are further clearly described. The described embodiments are only a part of the present invention and are used to explain the present invention but not to limit the present invention. Therefore, other embodiments obtained by other technicians in the field without creative work all belong to the protection scope of the present invention.

[0028] Gemini surfactant, purchased from Zhengzhou Yihe Fine Chemicals Co., Ltd.;

[0029] Chelating agents HEDP and ATMP were purchased from Shanghai MacLean Biochemical Technology Co., Ltd.

[0030] Example 1

[0031] A wettability reversal agent for high-temperature, high-salinity, low-permeability / tight oil reservoirs, wherein the raw materials are, by mass percentage, 40% Gemini surfactant solution (the mass concentration of Gemini surfactant is 50%), 50% hydroxyethylidene diphosphonic acid (HEDP) solution (the mass concentration of HEDP solution is 60%) and 10% water.

[0032] Among them, the structure of Gemini surfactant is:

[0033]

[0034] Preparation method:

[0035] (1) Add the above Gemini surfactant solution into water and stir at 25°C and 500 rpm for 15 min to obtain solution A;

[0036] (2) The HEDP solution was added to solution A and stirred at 25°C and 500 rpm for 15 min to obtain a wettability reversal agent.

[0037] Example 2

[0038] A wettability reversal agent for high-temperature, high-salinity, low-permeability / tight oil reservoirs, wherein the raw materials are, by mass percentage, 40% Gemini surfactant solution (the mass concentration of Gemini surfactant is 60%), 50% aminotrimethylenephosphonic acid (ATMP) solution (the mass concentration of ATMP solution is 50%) and 10% water.

[0039] Among them, the structure of Gemini surfactant is:

[0040]

[0041] Preparation method:

[0042] (1) Add the above Gemini surfactant solution into water, stir at 20°C and 600 rpm for 10 min to obtain solution A;

[0043] (2) The HEDP solution was added to solution A and stirred at 30°C and 400 rpm for 20 min to obtain a wettability reversal agent.

[0044] Example 3

[0045] A wettability reversal agent for high-temperature, high-salinity, low-permeability / tight oil reservoirs, wherein the raw materials are, by mass percentage, 40% Gemini surfactant solution (the mass concentration of Gemini surfactant is 60%), 25% aminotrimethylenephosphonic acid (ATMP) solution, 25% hydroxyethylidene diphosphonic acid (HEDP) solution (the mass concentrations of ATMP solution and HEDP solution are both 60%) and 10% water.

[0046] Among them, the structure of Gemini surfactant is:

[0047]

[0048] Preparation method:

[0049] (1) Add the above Gemini surfactant solution into water and stir at 25°C and 500 rpm for 15 min to obtain solution A;

[0050] (2) Add the HEDP solution and the ATMP solution into solution A, and stir at 25° C. and 500 rpm for 15 min to obtain a wettability reversal agent.

[0051] Example 4

[0052] A wettability reversal agent for high-temperature, high-salinity, low-permeability / tight oil reservoirs, wherein the raw materials are, by mass percentage, 40% Gemini surfactant solution (the mass concentration of Gemini surfactant is 40%), 25% aminotrimethylenephosphonic acid (ATMP) solution, 25% hydroxyethylidene diphosphonic acid (HEDP) solution (the mass concentrations of ATMP solution and HEDP solution are both 70%) and 10% water.

[0053] Among them, the structure of Gemini surfactant is:

[0054]

[0055] Preparation method:

[0056] (1) Add the above Gemini surfactant solution into water and stir at 30°C and 500 rpm for 15 min to obtain solution A;

[0057] (2) Add the HEDP solution and the ATMP solution into solution A, and stir at 30° C. and 500 rpm for 15 min to obtain a wettability reversal agent.

[0058] Comparative Example 1

[0059] A wettability reversal agent comprises, by weight percentage, 40% sodium dodecyl sulfate (SDS) surfactant solution (mass concentration is 60%), 50% hydroxyethylidene diphosphonic acid (HEDP) solution (mass concentration of HEDP solution is 60%) and 10% water.

[0060] Preparation method:

[0061] (1) Add the SDS surfactant solution into water and stir at 30°C and 500 rpm for 15 min to obtain solution A;

[0062] (2) Add the chelating agent to solution A, stir at 30° C. and 500 rpm for 15 min to obtain a wettability reversal agent.

[0063] Comparative Example 2

[0064] A wettability reversal agent for high-temperature, high-salinity, low-permeability / tight oil reservoirs, wherein the raw materials are, by mass percentage, 40% Gemini surfactant solution (the mass concentration of the Gemini surfactant is 50%), 50% ethylenediaminetetraacetic acid (EDTA) solution (the mass concentration of the EDTA solution is 60%) and 10% water.

[0065] Among them, the structure of Gemini surfactant is:

[0066]

[0067] Preparation method:

[0068] (1) Add the above Gemini surfactant solution into water and stir at 25°C and 500 rpm for 15 min to obtain solution A;

[0069] (2) Add EDTA solution to solution A and stir at 25°C and 500 rpm for 15 min to obtain a wetting reversal agent.

[0070] Comparative Example 3

[0071] A wettability reversal agent for high-temperature, high-salinity, low-permeability / tight oil reservoirs, wherein the raw materials are, by mass percentage, 30% Gemini surfactant solution (the mass concentration of Gemini surfactant is 50%), 60% hydroxyethylidene diphosphonic acid (HEDP) solution (the mass concentration of HEDP solution is 60%) and 10% water.

[0072] Among them, the structure of Gemini surfactant is:

[0073]

[0074] The preparation method is consistent with that in Example 1.

[0075] Effect test

[0076] Test Example 1 Contact Angle Test

[0077] Preparation of simulated formation water: prepare the mineralization degree of 5×10 4 mg / L and 10×10 4 mg / L of simulated water.

[0078] 500 mL of wettability reversal agent was filtered with filter paper, and the core was soaked in the filtrate at 95 °C for 8 hours. The core was taken out and aged at 85 °C for 10 hours, then cooled under natural conditions. The wettability angle of the wettability reversal agent on the rock surface was measured using a contact angle meter DSA30, and the wettability changes before and after imbibition were compared. Tables 1 and 2 are respectively the mineralization degree of 10×10 4 mg / L and 5×10 4 mg / L simulated formation water with 0.3% wettability reversal agent added. Table 3 shows the test results of the mineralization of 10×10 4 The test results of adding different concentrations of the wettability reversal agent in Example 1 into mg / L simulated formation water.

[0079] Table 1 Mineralization degree is 10×10 4 Contact angle test results of mg / L simulated formation water

[0080] Wetting reversal agent Contact angle before adding (°) Contact angle after adding for 8h (°) Example 1 123.3 40.3 Example 2 120.6 39.3 Example 3 128.7 43.3 Example 4 125.6 36.4 Comparative Example 1 127.7 79.6 Comparative Example 2 125.5 63.6 Comparative Example 3 124.6 49.3

[0081] Table 2 Mineralization degree is 5×10 4 Contact angle test results of mg / L simulated formation water

[0082]

[0083]

[0084] Table 3 Mineralization is 10×10 4 Test results of adding different concentrations of wetting reversal agent to mg / L simulated formation water

[0085]

[0086] Test Example 2 Oil recovery test by imbibition drainage

[0087] Place the core with a diameter of about 2.5 cm in a 95°C oven and dry it for 24 hours, then take out the core, cool the core to room temperature, weigh the core, record it as m0, and use a vernier caliper to measure the core diameter D and core length L to measure the core porosity. The permeability K is measured by gas. The core is vacuumed and saturated with oil and weighed, recorded as m1, and the oil saturation of the core is calculated. The core is placed in an imbibition bottle, and the wetting reversal agent is injected into the imbibition bottle using a constant pressure and constant speed pump. The imbibition bottle is placed in a 95℃ constant temperature water bath. After 24 hours, the upper and lower scales of the oil column in the scale glass tube above the imbibition bottle are read, and the oil phase volume V0 is recorded to calculate the imbibition oil recovery rate E. R , the calculation formula is as follows:

[0088]

[0089] Where: ER——imbibition oil recovery, expressed as percentage (%);

[0090] V0——oil phase volume, in milliliters (mL);

[0091] ρ0——density of crude oil, in grams per cubic centimeter (g / cm 3 );

[0092] m1——weight of the core after vacuum evacuation and saturation with oil, in grams (g);

[0093] m0——dry weight of core, in grams (g);

[0094] The test results of oil recovery by imbibition drainage are shown in Table 4.

[0095] Table 4 Test results of oil recovery factor of wetting reversal system

[0096]

[0097]

[0098] With 5×10 4 mg / L, 10×10 4 Compared with the imbibition rate of mg / L simulated water (7.9%, 8.3%), the wetting reversal system has a relatively high imbibition efficiency of 30.0%-40.0%. In the process of pressure displacement of low permeability / tight reservoirs, it can deepen the imbibition displacement effect and improve the oil displacement rate of fracturing fluid.

[0099] It can be seen that after being soaked in the compositions of Examples 1-8, the water contact angles on the core surfaces are all <50°, indicating that the compositions can reverse the wettability of the rock to water-wetness, thereby making the capillary force the driving force of the imbibition, deepening the imbibition replacement effect, and achieving an imbibition oil removal efficiency of more than 30%.

[0100] The above detailed description is a specific description of one feasible embodiment of the present invention. The embodiment is not intended to limit the patent scope of the present invention. Any equivalent implementation or modification that does not deviate from the present invention should be included in the scope of the technical solution of the present invention.

Claims

1. A wettability reversal agent, characterized in that: The raw materials of the wettability reversal agent include Gemini surfactant solution, chelating agent solution and water.

2. The wettability reversal agent according to claim 1, characterized in that: Calculated by weight percentage, the raw materials of the wettability reversal agent include 40%-45% Gemini surfactant solution, 45%-50% chelating agent solution and the balance water.

3. The preparation method according to claim 1, characterized in that: The mass concentration of the Gemini surfactant solution in step (1) is 40%-60%.

4. The preparation method according to claim 1, characterized in that: The mass concentration of the chelating agent solution in step (2) is 50%-70%.

5. The wettability reversal agent according to claim 1, characterized in that: The Gemini surfactant is a diquaternary ammonium salt surfactant, and the molecular formula structure of the diquaternary ammonium salt surfactant is as follows: Among them, n is 8-12.

6. The wettability reversal agent according to claim 1, characterized in that: The chelating agent is selected from one or both of hydroxyethylidene diphosphonic acid and aminotrimethylene phosphonic acid.

7. A method for preparing the wettability reversal agent according to any one of claims 1 to 6, characterized in that: The following steps are involved: (1) Adding the Gemini surfactant solution into water and stirring to obtain solution A; (2) Add the chelating agent solution into solution A and stir to obtain a wettability reversal agent.

8. The preparation method according to claim 7, characterized in that: The stirring speed in step (1) and step (2) is 300-600 rpm, the stirring time is 10-20 min, and the stirring temperature is 20-30°C.

9. Use of the wettability reversal agent according to any one of claims 1 to 6 in oil and gas drilling.

10. The use according to claim 9, characterized in that: The wettability reversal agent is used in an amount of 0.1-0.5 parts by weight relative to 100 parts by weight of water in the water-based drilling fluid.

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