CN115614010A - Hydrophobic modification method of rock surface in carbonate rock reservoir - Google Patents

Abstract

The invention discloses a method for hydrophobizing and modifying the rock surface of carbonate rock reservoirs, which belongs to the field of oil and gas field reservoir transformation and is used to solve the problem of long well sections and low reservoir permeability during the acidification process of carbonate rock reservoirs. , serious heterogeneity and other problems caused by the acid liquid’s sweeping distance in the reservoir is small, and it is difficult to control the distribution of acid, so as to improve the effect of reservoir acidification transformation. The surface hydrophobization modification method of carbonate rock reservoir rocks is as follows: prepare a mixture of organic acid (or organic acid salt) and water and inject it into carbonate rock reservoir rocks to promote organic acid (or organic acid salt) and water The surface material of the reservoir rock reacts and forms a stable hydrophobic precipitate on the surface of the reservoir rock, making the rock surface hydrophobic. The hydrophobicity of the modified reservoir rock surface can isolate the rock surface from the water-based acid solution and achieve the purpose of anti-acid corrosion. The method has the advantages of simple process, low cost, no pollution, etc., and is widely applicable to reservoir stimulation treatment of carbonate rock type oil and gas reservoirs.

Description

A Hydrophobic Modification Method of Carbonate Reservoir Rock Surface

technical field

The invention belongs to the field of reservoir transformation of oil and gas fields, and in particular relates to a method for hydrophobizing and modifying the rock surface of carbonate rock reservoirs.

Background technique

The oil and gas resources contained in carbonate oil and gas reservoirs account for about half of the global reserves, and the current production accounts for more than 60% of the total production. my country's carbonate rock oil and gas resources are about 38.5 billion tons of oil equivalent, and the distribution is very wide, with great potential for exploration and development. However, due to the complex geological conditions and strong heterogeneity of carbonate reservoirs, the development of fracture-cavity systems in carbonate reservoirs cannot be described in detail using current geophysical prospecting techniques, and drilling can only reach the fracture-cave systems predicted by earthquakes. Therefore, the development of carbonate oil and gas reservoirs is still relatively difficult. Usually, carbonate reservoirs need to undergo reservoir transformation to achieve the purpose of understanding the reservoir and increasing reserves and production.

Acidizing is one of the most important technologies for carbonate rock reservoir reconstruction. Its main principle is to restore or improve reservoir pores and Permeability of cracks. Since the main components of carbonate reservoirs are dolomite and calcite, acidizing them can produce better reservoir stimulation effect. However, problems such as long well intervals or extremely thick layers are often encountered in acidizing carbonate reservoirs, resulting in poor acid deployment effects. At the same time, the acid liquid reacts rapidly with the reservoir rock near the wellbore, causing a large amount of acid liquid to be consumed in the near wellbore area, and the dissolution of the reservoir near the wellbore is intensified, resulting in the problem that the acid liquid does not spread far enough. In order to improve the effect of acid distribution and increase the acid liquid sweeping distance, it is necessary to carry out acid prevention treatment for the reservoir near the wellbore and reduce the consumption of acid liquid near the wellbore.

In view of the above problems, the present invention discloses a method for hydrophobizing and modifying the rock surface of carbonate rock reservoirs, which improves the acid resistance of rocks in near-wellbore reservoirs, thereby improving the distribution and spread of acid liquid in carbonate rock reservoirs. distance, improve reservoir permeability and achieve the purpose of increasing oil and gas production.

Contents of the invention

The object of the invention is to provide a method for hydrophobizing and modifying the rock surface of a carbonate rock reservoir. Carbonate reservoir rocks are modified with organic acids (or organic acid salts) to make the surface become hydrophobic, so as to achieve the effect of acid corrosion resistance.

In order to achieve the above object, the present invention provides a method for hydrophobizing the surface of carbonate reservoir rock, comprising the following steps:

(1) Preparation of organic acid (or organic acid salt)/water mixture

Take an appropriate amount of water, add an appropriate amount of organic acid (or organic acid salt) therein; heat the mixture to a certain temperature, and stir the mixture to make the two evenly mixed.

Wherein: the molecular structure of organic acids (or organic acid salts) includes hydrophobic groups and carboxyl groups, such as stearic acid, sodium caprate, perfluorododecanoic acid, etc.; organic acids (or organic acid salts) can be An organic acid (or organic acid salt), or a mixture of two or more organic acids (or organic acid salts), or a mixture of organic acids and organic acid salts; organic acid (or organic acid salt) The mass percentage in the mixed solution formed with water is 0.0001wt%-20wt%; the heating temperature is -60°C-150°C.

(2) Reaction of organic acid (or organic acid salt)/water mixture with carbonate reservoir rocks

Inject the organic acid (or organic acid salt)/water mixture prepared in step (1) into the carbonate reservoir rock, so that the organic acid (or organic acid salt)/water mixture and carbonate The material on the rock surface of the rock reservoir reacts at a certain temperature to form a stable hydrophobic precipitation on the rock surface, so that the wettability of the rock surface is hydrophobic.

Among them: the reaction temperature between the organic acid (or organic acid salt)/water mixture and the reservoir rock is -60°C to 150°C; the reaction time between the organic acid (or organic acid salt)/water mixture and the reservoir rock is 5 Minutes to 30 days.

The beneficial effects of the present invention are:

1. The method for hydrophobizing and modifying the rock surface of carbonate rock reservoirs provided by the present invention has the advantages of simple process, low cost, and no pollution, and is widely applicable to the reservoir modification treatment of carbonate rock reservoirs.

2. The carbonate reservoir rock treated by the method for hydrophobizing the surface of the carbonate reservoir rock provided by the present invention has good hydrophobicity, and water droplets do not spread on the rock surface, so that it has good anti-corrosion properties. Corrosive properties of water-based acids.

Description of drawings

Fig. 1 is a picture of the contact angle of water droplets on the surface of carbonate rock reservoir treated by the method for modifying the surface of carbonate rock reservoir rock according to the present invention.

detailed description

Example 1

Take 300mL of clear water and put it in a 1L beaker, add 0.3g of stearic acid into it, and stir vigorously at 80°C to make the stearic acid and water mix evenly.

Place the carbonate rock core sample in the core displacement device, and inject the prepared stearic acid/water mixture into the core through high-pressure displacement under the condition of 80°C, keep the core temperature at 80°C, Let stand for 1 hour.

The treated core was taken out, dried, and the water droplet contact angle on the surface of the core was measured. As shown in Fig. 1 (left), the modified carbonate rock core has good hydrophobicity, and the water droplet contact angle is 146°.

Example 2

Take 300mL of formation salt water and put it in a 1L beaker, add 0.1g of sodium caprate to it, and stir vigorously at 40°C to make the capric acid and water evenly mixed.

The carbonate rock core samples were placed in the core displacement device, and the prepared sodium caprate/water mixture was injected into the core through high-pressure displacement at 40°C, and the core temperature was kept at 40°C. Let stand for 3 hours.

The treated core was taken out, dried, and the water droplet contact angle on the surface of the core was measured. As shown in Fig. 1 (right), the modified carbonate rock core has good hydrophobicity, and the water droplet contact angle is 134°.

Example 3

Under the condition of 25° C., prepare 1000 tons of pelargonic acid/low salinity water mixed solution with a pelargonic acid concentration of 0.03 wt%.

The above mixed solution is injected into the carbonate rock reservoir through the oil well, and the well is shut down for 24 hours under the reservoir temperature condition, so that the surface of the reservoir rock near the wellbore is modified into a hydrophobic surface.

Although the specific implementation manner of the present invention has been described in detail in conjunction with the accompanying drawings, it should not be construed as limiting the protection scope of this patent. Within the scope described in the claims, various modifications and deformations that can be made by those skilled in the art without creative work still belong to the protection scope of this patent.

Claims (7)

1. a method for hydrophobizing modification of carbonate rock reservoir rock surface, is characterized in that, described method comprises the steps: (1) Add an appropriate amount of organic acid (or organic acid salt) to an appropriate amount of water, control the temperature of the mixture and stir, so that the organic acid (or organic acid salt) and water are evenly mixed to make an organic acid (or organic acid salt) )/water mixture; (2) Inject the organic acid (or organic acid salt)/water mixture prepared in step (1) into carbonate reservoir rocks, so that the organic acid (or organic acid salt) and carbon The substances on the rock surface of salt rock reservoirs react at a certain temperature to form stable hydrophobic precipitates on the rock surface, thereby realizing the hydrophobic modification of the rock surface. 2. A method for hydrophobizing and modifying the surface of carbonate rock reservoir rocks according to claim 1, characterized in that: in the step (1), the structure of the organic acid (or organic acid salt) includes Hydrophobic groups and carboxyl groups. 3. A method for hydrophobizing and modifying the surface of carbonate rock reservoir rocks according to claim 1, characterized in that: in the step (1), the organic acid (or organic acid salt) can be a Organic acids (or organic acid salts) can also be a mixture of two or more organic acids (or organic acid salts), or a mixture of organic acids and organic acid salts. 4. A method for hydrophobizing and modifying the surface of carbonate rock reservoir rocks according to claim 1, characterized in that: the organic acid (or organic acid salt) in the mixture formed in the step (1) ) concentration is 0.0001wt% ~ 20wt%. 5. The method for hydrophobizing and modifying the surface of carbonate rock reservoir rocks according to claim 1, characterized in that: in the step (1), the temperature is -60°C ~ 150°C. 6. The method for hydrophobizing and modifying the rock surface of carbonate rock reservoirs according to claim 1, characterized in that: in the step (2), the reaction temperature is -60°C ~ 150°C. 7. The method for hydrophobizing and modifying the surface of carbonate rock reservoir rocks according to claim 1, characterized in that: in the step (2), the reaction time is 5 minutes to 30 days.

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