A wetting reversal agent, its preparation method and application

Abstract

This invention belongs to the field of oil and gas field development technology, specifically relating to a wetting reversal agent, its preparation method, and its application. The wetting reversal agent, by weight percentage, comprises 40%-45% Gemini surfactant solution, 45%-50% chelating agent solution, and the balance being water. The wetting reversal agent of this invention is suitable for high-temperature, high-salinity, low-permeability / tight oil reservoirs, and the salinity of the water used in its preparation is 5 × 10⁻⁶. 4 mg / L-10×10 4 mg / L, calcium and magnesium ions ≤1000 mg / L, temperature ≤95℃, permeability ≤10mD; and it has good permeation efficiency.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas field development technology, specifically relating to a wetting reversal agent, its preparation method, and its application. Background Technology

[0002] China has a wide distribution of low-permeability / tight oil and a huge amount of recoverable resources, making it the most important future oil resource. The most prominent problems exposed in the development 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 is very rapid, and the cycle of production using natural energy and water injection is very short. Although technologies such as horizontal wells and multi-stage volumetric fracturing can effectively increase single-well production in the early stages of development, after fracturing and commissioning, single-well production usually drops to less than 20% of the initial production within one year, gradually entering a stable production stage with low decline rate and low production after 9-12 months. The rapid decline in well production inevitably leads to extremely low recovery rates for low-permeability / tight oil: In foreign countries, the recovery rate of single-stage elastic production in low-permeability / tight oil reservoir evaluation volumetric fracturing development is only 5%-10%, and some scholars believe it can even be as low as 1%-2%, leaving a huge amount of crude oil underground after the first development. Even with secondary water injection, the effects of crossflow are minimal or no effective means of improving oil recovery in low-permeability / tight oil reservoirs. Therefore, significantly improving the recovery rate of low-permeability / tight oil reservoirs is the only way forward for their development.

[0003] Due to the tightness of reservoirs, injected water often cannot directly penetrate the low-permeability / tight matrix to displace crude oil. Instead, it mainly flows within fracturing or natural fractures. Thus, the fluid displacement between the aqueous phase in the fractures and the crude oil in the low-permeability / tight matrix, based on the "permeation effect," becomes crucial for improving the recovery rate of low-permeability / tight oil. In traditional medium / high-permeability reservoir water injection development, the permeation and drainage mechanism of the aqueous phase has been emphasized, and numerous studies have been conducted on surfactant-assisted enhancement of the aqueous phase permeation effect, resulting in some highly efficient permeation systems. However, for low-permeability / tight reservoirs, which are even denser and have lower permeability, the main driving force for permeation changes significantly compared to traditional medium / high-permeability reservoirs. This means that some existing permeation systems cannot be directly used to improve the recovery rate of low-permeability / tight reservoirs. Furthermore, general surfactant systems are no longer suitable for high-temperature and high-salinity conditions.

[0004] Chinese invention patent application CN201911011026.5 discloses a biological wetting reversal agent for high-temperature, high-salinity heavy oil reservoirs. Its composition and components are as follows: 20-30 wt% rhamnolipin fermentation broth; 15-20 wt% sophorolipid fermentation broth; 3-5 wt% alkyl polyglycosides; 0.1-0.3 wt% alcohol auxiliaries; and water as the balance. It is suitable for heavy oil reservoirs with a temperature greater than 80℃ and a salinity greater than 30,000 mg / L, especially for oil wells with a comprehensive water cut of more than 95% after multiple rounds of cold production. However, its adaptability to low-permeability / tight reservoirs with a salinity of 100,000 mg / L is unclear.

[0005] Chinese invention patent application CN110467912A discloses a high-temperature triggered wetting reversal agent, its preparation method, and its application. This wetting reversal agent protects the primary amine by reacting phthalic anhydride with a primary amine to generate phthalimide, and then combines long-chain alkyl groups with amino groups through the reaction of bromoalkane with a secondary amine. Under the high temperature of the oil and gas reservoir, it transforms into an anionic surfactant carrying multiple carboxyl groups. At the reversal layer, it forms a mixed adsorption layer with the polar substances originally adsorbed on the surface, producing an emulsification effect, thereby changing the wettability of the rock wall to a certain extent and improving the final recovery rate. However, it is only suitable for high-temperature reservoirs, and its adaptability to low-permeability / tight reservoirs with high salinity is unclear.

[0006] Chinese invention patent application CN106634894A discloses a dual-cationic fluorocarbon surfactant used as a wetting reversal agent in oil and gas drilling, which imparts hydrophobic and oleophobic properties to rocks. It is a dual-repellent agent that achieves hydrophobic and oleophobic treatment of rock surfaces, particularly effective in drilling easily hydrated shale and mudstone, preventing water and oil ingress, inhibiting capillary action, and stabilizing the wellbore and protecting the reservoir. However, it is only suitable for oil and gas drilling and cannot be used to enhance oil recovery in high-temperature, high-salinity, low-permeability / tight oil reservoirs. Summary of the Invention

[0007] To address the lack of wetting reversal agents in high-temperature, high-salinity reservoirs, this invention provides a wetting reversal agent, its preparation method, and its application. This invention establishes a method for preparing a wetting reversal agent for high-temperature, high-salinity, low-permeability / tight reservoirs by combining a highly active Gemini surfactant with a chelating agent, constructing a wetting reversal permeation system. This solves the key problem of the lack of wetting reversal agents in low-permeability, high-temperature, high-salinity reservoirs. This system effectively alters the wettability of high-temperature, high-salinity, low-permeability / tight reservoirs, achieving efficient permeation and drainage, thereby improving the recovery rate of low-permeability / tight reservoirs.

[0008] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

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

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

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

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

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

[0014]

[0015] Where n is 8-12.

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

[0017]

[0018] This invention also relates to a method for preparing the above-mentioned wetting reversal agent, comprising the following steps:

[0019] (1) Add the Gemini surfactant solution to water and stir to obtain solution A;

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

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

[0022] This invention also relates to the application of the above-mentioned wetting reversal agent in oil and gas drilling.

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

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

[0025] (1) The wetting reversal agent of the present invention is suitable for high-temperature, high-salinity, low-permeability / tight oil reservoirs, and the salinity of the water used for preparation is 5×10.4 mg / L-10×10 4 mg / L, calcium and magnesium ions ≤1000 mg / L, temperature ≤95℃, permeability ≤10mD;

[0026] (2) The wetting reversal agent of the present invention has a good penetration efficiency of 30.0%-40.0%. Detailed Implementation

[0027] The technical solutions in the embodiments of the present invention will be further described in detail below. The described embodiments are only a part of the present invention and are used to explain the present invention, but are not intended to limit the present invention. Therefore, other embodiments obtained by other people skilled in the art without creative labor are all within the protection scope of the present invention.

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

[0029] The chelating agents HEDP and ATMP were both purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0030] Example 1

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

[0032] The structure of the Gemini surfactant is as follows:

[0033]

[0034] Preparation method:

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

[0036] (2) Add HEDP solution to solution A, stir at 25°C and 500 rpm for 15 min to obtain wetting reversal agent.

[0037] Example 2

[0038] A wetting reversal agent for high-temperature, high-salinity, low-permeability / tight oil reservoirs, comprising, by mass percentage: 40% Gemini surfactant solution (Gemini surfactant mass concentration is 60%), 50% aminotrimethylenephosphonic acid (ATMP) solution (ATMP solution mass concentration is 50%), and 10% water.

[0039] The structure of the Gemini surfactant is as follows:

[0040]

[0041] Preparation method:

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

[0043] (2) Add HEDP solution to solution A, stir at 30°C and 400 rpm for 20 min to obtain wetting reversal agent.

[0044] Example 3

[0045] A wetting reversal agent for high-temperature, high-salinity, low-permeability / tight oil reservoirs, comprising, by mass percentage: 40% Gemini surfactant solution (Gemini surfactant mass concentration is 60%), 25% aminotrimethylenephosphonic acid (ATMP) solution, 25% hydroxyethylidene diphosphonic acid (HEDP) solution (ATMP solution and HEDP solution both mass concentration is 60%), and 10% water.

[0046] The structure of the Gemini surfactant is as follows:

[0047]

[0048] Preparation method:

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

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

[0051] Example 4

[0052] A wetting reversal agent for high-temperature, high-salinity, low-permeability / tight oil reservoirs, comprising, by mass percentage: 40% Gemini surfactant solution (Gemini surfactant mass concentration is 40%), 25% aminotrimethylenephosphonic acid (ATMP) solution, 25% hydroxyethylidene diphosphonic acid (HEDP) solution (ATMP solution and HEDP solution both mass concentration is 70%), and 10% water.

[0053] The structure of the Gemini surfactant is as follows:

[0054]

[0055] Preparation method:

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

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

[0058] Comparative Example 1

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

[0060] Preparation method:

[0061] (1) Add the SDS surfactant solution to 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 the wetting reversal agent.

[0063] Comparative Example 2

[0064] A wetting reversal agent for high-temperature, high-salinity, low-permeability / tight oil reservoirs, comprising, by mass percentage: 40% Gemini surfactant solution (Gemini surfactant mass concentration is 50%), 50% ethylenediaminetetraacetic acid (EDTA) solution (EDTA solution mass concentration is 60%), and 10% water.

[0065] The structure of the Gemini surfactant is as follows:

[0066]

[0067] Preparation method:

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

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

[0070] Comparative Example 3

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

[0072] The structure of the Gemini surfactant is as follows:

[0073]

[0074] The preparation method is the same as in Example 1.

[0075] Effect test

[0076] Test Example 1: Contact Angle Test

[0077] Preparation of simulated formation water: Prepare water with a salinity of 5×10⁻⁶. 4 mg / L and 10×10 4 Simulated water at mg / L.

[0078] 500 mL of wetting reversal agent was filtered through filter paper. The core sample was soaked in the filtrate at 95℃ for 8 hours. The core sample was then removed and aged at 85℃ for 10 hours. After cooling under natural conditions, the wetting angle of the wetting reversal agent on the rock surface was measured using a DSA30 contact angle meter to compare the changes in wettability before and after infiltration. Tables 1 and 2 show the results for a mineralization degree of 10 × 10⁻⁶. 4 mg / L and 5×10 4 The test results were obtained by adding 0.3% wetting reversal agent to simulated formation water at a concentration of mg / L. Table 3 shows the results for a salinity of 10 × 10⁻⁶ mg / L. 4 Test results of adding different concentrations of the wetting reversal agent from Example 1 to simulated formation water at mg / L.

[0079] Table 1 shows a mineralization degree of 10×10. 4 mg / L Simulated Formation Water Contact Angle Test Results

[0080] Wetting reversal agent Add front contact angle (°) Contact angle (°) after 8 hours of application 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 shows a mineralization degree of 5×10. 4 mg / L Simulated Formation Water Contact Angle Test Results

[0082]

[0083]

[0084] Table 3 shows a mineralization degree of 10×10. 4 Test results of adding different concentrations of wetting reversal agent to simulated formation water at mg / L

[0085]

[0086] Test Example 2: Oil Recovery Test

[0087] After drying the core sample (approximately 2.5 cm in diameter) in a 95℃ oven for 24 hours, remove the core and allow it to cool to room temperature. Weigh the core and record the weight as m0. Measure the core diameter D and length L using calipers, and also measure the core porosity. Permeability K was measured using gas extraction. After vacuum-saturating the core with oil, the core was weighed and recorded as m1. The oil saturation of the core was calculated. The core was then placed in an adsorption flask, and a wetting reversal agent was injected into the flask using a constant pressure and constant speed pump. The adsorption flask was placed in a 95℃ constant temperature water bath. After 24 hours, the upper and lower scales of the oil column in the graduated glass tube above the adsorption flask were read, and the oil phase volume V0 was recorded. The oil recovery rate E was calculated. R The calculation formula is as follows:

[0088]

[0089] Where: ER——oil recovery rate from seepage, expressed as a percentage (%);

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

[0091] ρ0 — Crude oil density, in grams per cubic centimeter (g / cm³) 3 );

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

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

[0094] The results of the oil recovery rate test for seepage drainage are shown in Table 4.

[0095] Table 4 Results of oil recovery tests for the wetting reversal system.

[0096]

[0097]

[0098] With 5×10 4 mg / L, 10×10 4 Compared to simulated water permeation (7.9% and 8.3%), this wetting reversal system exhibits a relatively high permeation efficiency, reaching 30.0%-40.0%. During hydraulic displacement in low-permeability / tight reservoirs, it can deepen the permeation and displacement process, thereby increasing the fracturing fluid permeation and oil discharge rate.

[0099] As can be seen, after soaking with the compositions of Examples 1-8, the contact angle of the water phase on the core surface is all <50°. This indicates that the composition can reverse the wettability of the rock to water wettability, thereby making the capillary force the driving force for percolation and deepening the percolation and replacement effect, with a percolation and oil discharge efficiency of over 30%.

[0100] The above detailed description is a specific description of one of the feasible embodiments of the present invention. This embodiment is not intended to limit the patent scope of the present invention. All equivalent implementations or modifications that do not depart from the present invention should be included within the scope of the technical solution of the present invention.

Claims

1. A wetting reversal agent, characterized in that, By weight percentage, the raw materials of the wetting reversal agent include 40%-45% of Gemini surfactant solution, 45%-50% of chelating agent solution and the balance water; The Gemini surfactant is a bisquaternary ammonium salt surfactant, and the molecular formula of the bisquaternary ammonium salt surfactant is as follows: ； Where n is 8-12; The chelating agent is selected from one or both of hydroxyethylidene diphosphonic acid and aminotrimethylene phosphonic acid.

2. The wetting reversal agent according to claim 1, characterized in that, The mass concentration of the Gemini surfactant solution is 40%-60%.

3. The wetting reversal agent according to claim 1, characterized in that, The chelating agent solution has a mass concentration of 50%-70%.

4. A method for preparing the wetting reversal agent according to any one of claims 1-3, characterized in that, Includes the following steps: (1) Add the Gemini surfactant solution to water and stir to obtain solution A; (2) Add the chelating agent solution to solution A and stir to obtain the wetting reversal agent.

5. The preparation method according to claim 4, characterized in that, The stirring speed in steps (1) and (2) is 300-600 rpm, the stirring time is 10-20 min, and the stirring temperature is 20-30℃.

6. The application of the wetting reversal agent according to any one of claims 1-3 in oil and gas drilling.

7. The application according to claim 6, characterized in that, When using water-based drilling fluid in oil and gas drilling, the amount of the wetting reversal agent is 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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