CN111257159A - Evaluation method for dispersion and removal effects of carbonaceous asphalt in carbonate reservoir - Google Patents

Abstract

The invention discloses an evaluation method for the dispersion and removal effects of carbonaceous asphalt in a carbonate reservoir, which comprises the following steps of extracting the carbonaceous asphalt in the carbonate reservoir, weighing the carbonaceous asphalt with initial mass, stirring and mixing the carbonaceous asphalt with a dispersant solution or a remover solution to obtain a suspension, testing the turbidity and particle size of the suspension, calculating the dispersion value lambda of the carbonaceous asphalt according to the turbidity and the particle size, wherein the larger the dispersion value lambda is, the better the dispersion effect is, testing the residual mass of the carbonaceous asphalt after filtering, washing and drying the suspension, and calculating the removal rate η of the carbonaceous asphalt, wherein the larger the removal rate η is, the better the removal effect is.

Description

A method for evaluating the dispersion and removal effect of carbonaceous asphalt in carbonate reservoirs

technical field

The invention relates to the technical field of dispersion and removal of carbonaceous pitch, in particular to a method for evaluating the effect of dispersion and removal of carbonaceous pitch in carbonate rock reservoirs.

Background technique

Asphalt is a mixture of extremely complex macromolecular hydrocarbons and non-metallic derivatives of these hydrocarbons. It is a kind of high-viscosity organic liquid. It is liquid with a black surface and is soluble in carbon disulfide. Generally, it can be divided into three categories: coal tar pitch, petroleum pitch and natural pitch. Among them, coal tar pitch is a by-product of coking. Petroleum bitumen is the residue after the distillation of crude oil. Natural bitumen is stored underground, and some form mineral layers or accumulate on the surface of the earth's crust.

Reservoir bitumen is a kind of natural bitumen, which is widely distributed in carbonate reservoirs as an associated product of oil and gas. It plays an important role in controlling the physical properties of the reservoir and the migration and accumulation of oil and gas in the later stage. Asphalt filling reduces the porosity and permeability of the reservoir and enhances the heterogeneity.

Carbonaceous pitch is the product of further carbonization of reservoir pitch. It is black solid, rich in carbon and depleted in hydrogen, no fluorescence, high reflectivity, and high maturity. In the process of acid fracturing of carbonate reservoirs, acid corrosion cracks are generated and bitumen is freed at the same time. The existence of free bitumen will lead to the reduction of acid corrosion conductivity. In order to improve the effect of acid fracturing, various methods have been developed. A carbonaceous pitch dispersant or remover is added to the acid system as an additive.

For low-maturity asphalt such as colloidal asphalt, its dissolution rate or viscosity is often used as an evaluation index for dispersants or removers; however, high-maturity carbonaceous asphalt is not gelatinous like other asphalts, but It is in the form of solid particles. For the dispersion and removal of this kind of asphalt, the current idea is to partially dissolve and disperse it, but there is no systematic evaluation method for this, and it is obviously not applicable to the evaluation of colloidal asphalt. method.

SUMMARY OF THE INVENTION

In view of the above problems, the present invention aims to provide a method for evaluating the effect of dispersing and removing carbonaceous pitch in carbonate rock reservoirs.

The technical scheme of the present invention is as follows:

A method for evaluating the dispersion and removal effect of carbonaceous pitch in carbonate rock reservoirs, comprising the following steps:

extracting carbonaceous pitch in the carbonate reservoir;

Weigh the initial mass of carbonaceous pitch, stir and mix it with the dispersant solution or the remover solution to obtain a suspension;

Carry out the test of turbidity and particle diameter to described suspension, according to described turbidity and particle diameter, calculate the dispersion value λ of described carbonaceous pitch, the bigger described dispersion value λ, the better dispersion effect;

The residual mass of the carbonaceous pitch is tested after the suspension is filtered, washed and dried, and the removal rate η of the carbonaceous pitch is calculated. The larger the removal rate η is, the better the removal effect is.

Preferably, when the carbonaceous pitch is extracted, excess hydrochloric acid is used to acid-dissolve the carbonate rock reservoir, and then the carbonaceous pitch is obtained by washing, filtering and drying.

Preferably, the rotating speed when the carbonaceous pitch is stirred and mixed with the dispersant solution or the remover solution is 125r/min～375r/min.

Preferably, the stirring time when the carbonaceous pitch is stirred and mixed with the dispersant solution or the remover solution is 10 min to 45 min.

Preferably, when the suspension is tested for turbidity and particle size, the liquid in the middle of the suspension is extracted for testing.

Preferably, it also includes the following steps: weighing the carbonaceous pitch of the same initial quality, preparing a comparative suspension by using clear water, carrying out a comparative experiment, and calculating the dispersion value λ ₀ and the removal rate η ₀ of the carbonaceous pitch under the action of clear water. .

Preferably, the calculation method of the dispersion value λ is as follows:

λ=N/D (1)

In the formula: λ is the dispersion value, NTU/μm; N is the turbidity, NTU; D is the particle size, μm.

As preferably, the calculation method of described removal rate η is as follows:

In the formula: η is the removal rate, %; m is the initial mass of carbonaceous pitch, g; M is the remaining mass of carbonaceous pitch, g.

Compared with the prior art, the present invention has the following advantages:

The invention can quantitatively evaluate the effect of the dispersant or the remover on the carbonaceous pitch, and has various evaluation indexes, good stability, high accuracy, good reproducibility, easy operation, and can be used for various carbonaceous pitch dispersants or removers. It can detect the effect of the agent, and at the same time facilitate the research and development of the carbonaceous asphalt dispersant or remover.

Detailed ways

The present invention will be further described below in conjunction with the examples. It should be noted that the embodiments in this application and the technical features in the embodiments may be combined with each other under the condition of no conflict.

The invention provides a method for evaluating the dispersion and removal effect of carbonaceous pitch in carbonate rock reservoirs, comprising the following steps:

First, the carbonaceous pitch in the carbonate reservoir is extracted. In a specific embodiment, when the carbonaceous pitch is extracted, excess hydrochloric acid is used to acid-dissolve the carbonate reservoir, and then the carbonaceous pitch is obtained by washing, filtering and drying.

Next, weigh the initial mass of carbonaceous pitch, stir and mix it with the dispersant solution or the remover solution to obtain a suspension.

In a specific embodiment, the rotating speed during stirring and mixing is 125r/min～375r/min, and the stirring time is 10min～45min.

Then, test the turbidity and particle size of the suspension. According to the turbidity and particle size, formula (1) is used to calculate the dispersion value λ of the carbonaceous pitch. The larger the dispersion value λ, the better the dispersion. The better the effect.

Finally, the residual mass of the carbonaceous pitch is tested after the suspension is filtered, washed and dried, and formula (2) is used to calculate the removal rate η of the carbonaceous pitch. The larger the removal rate η, the better the removal effect. .

In a specific embodiment, the suspension for the dispersion value test and the suspension for the removal rate test are the same suspension. During the specific operation, the dispersion value test is first performed on it, and then the tested suspension is combined with the rest of the suspension. The suspension is mixed and then tested for removal rate.

In another specific embodiment, the suspension for the dispersion value test and the suspension for the removal rate test are two suspensions prepared by the same method, and the dispersion value test is performed on one of the suspensions, and the other A portion of the suspension is subjected to the removal rate test, and at this time, the steps of the dispersion value test and the removal rate test can be interchanged.

Optionally, the present invention also includes the following steps: weighing the carbonaceous pitch of the same initial quality, using clear water to prepare a comparative suspension, carrying out a comparative experiment, calculating the dispersion value λ ₀ of the carbonaceous pitch under the action of clear water and removing it. rate η ₀ ;

If the dispersion value λ under the action of the dispersant solution or the remover solution is less than or equal to λ ₀ , the dispersion effect of the dispersant or the remover solution is not good;

If the dispersion value λ under the action of the dispersant solution or remover solution is greater than λ ₀ , the greater the difference between λ and λ ₀ , the better the dispersion effect of the dispersant or remover;

If the removal rate η under the action of the dispersant solution or the remover solution is less than or equal to η ₀ , the removal effect of the dispersant or the remover is not good;

If the removal rate η under the action of the dispersant solution or remover solution is greater than η ₀ , the larger the difference between η and η ₀ is, the better the removal effect of the dispersant or remover is.

In a specific embodiment, adopt the evaluation method of the present invention to evaluate the removal effect of carbon disulfide, toluene and sodium hypochlorite, specifically comprising the following steps:

1) Extraction of carbonaceous pitch: use excess hydrochloric acid to dissolve the carbonate rock of Longwangmiao Formation in Longnüsi block in central Sichuan, filter, wash the residue twice with distilled water, and dry it in an oven at 105 ° C, the obtained residue is carbon Asphalt. During concrete operation, according to the reaction equation of hydrochloric acid and carbonate rock and the weight of described carbonate rock, the consumption of described hydrochloric acid is determined, and the consumption of described hydrochloric acid is greater than the consumption of the hydrochloric acid reacted with described carbonate rock.

2) take by weighing four parts of the carbonaceous pitch that is 2g in quality, put into four 250mL beakers respectively, then add 200mL of clear water, carbon disulfide solution, toluene solution, 15% sodium hypochlorite solution to the beaker respectively, then in the The suspension was obtained by stirring at 280 r/min for 25 min at room temperature.

3) the suspension is filtered, the residue is washed twice with distilled water, then the residue is dried in an oven at 105°C, and the remaining mass of carbonaceous pitch under the action of clear water, carbon disulfide solution, toluene solution, and sodium hypochlorite solution is recorded to be 2g respectively. , 1.9945g, 1.9951g, 1.9647g, according to formula (2), the removal rates of the carbonaceous pitch under the action of clear water, carbon disulfide solution, toluene solution, and sodium hypochlorite solution were calculated as 0%, 0.275%, 0.245%, 1.765 %. According to the removal rate results, it can be known that the carbon sulfide solution and the toluene solution have a slightly better removal effect on the carbonaceous pitch than clear water, and the sodium hypochlorite solution has a better removal effect on the carbonaceous pitch.

The above are only preferred embodiments of the present invention, and do not limit the present invention in any form. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Technical personnel, within the scope of the technical solution of the present invention, can make some changes or modifications to equivalent examples of equivalent changes by using the technical content disclosed above, but any content that does not depart from the technical solution of the present invention, according to the present invention. The technical essence of the invention Any simple modifications, equivalent changes and modifications made to the above embodiments still fall within the scope of the technical solutions of the present invention.

Claims (8)

1. The method for evaluating the dispersion and removal effects of the carbonaceous asphalt in the carbonate reservoir is characterized by comprising the following steps of:

extracting carbonaceous bitumen in the carbonate reservoir;

weighing carbonaceous asphalt with initial mass, and stirring and mixing the carbonaceous asphalt with a dispersant solution or a remover solution to obtain a suspension;

carrying out turbidity and particle size tests on the suspension, and calculating the dispersion value lambda of the carbonaceous asphalt according to the turbidity and the particle size, wherein the larger the dispersion value lambda is, the better the dispersion effect is;

and (3) filtering, washing and drying the suspension, testing the residual mass of the carbonaceous asphalt, and calculating the removal rate η of the carbonaceous asphalt, wherein the removal effect is better when the removal rate η is larger.

2. The method for evaluating the dispersing and removing effects of the carbonaceous asphalt in the carbonate reservoir according to claim 1, wherein during the extraction of the carbonaceous asphalt, the carbonaceous asphalt is obtained by acid-dissolving the carbonate reservoir with an excessive amount of hydrochloric acid, and then washing, filtering and drying the carbonate reservoir.

3. The method for evaluating the dispersing and removing effect of the carbonaceous asphalt in the carbonate reservoir according to claim 1, wherein the rotation speed of the carbonaceous asphalt when the carbonaceous asphalt is stirred and mixed with the dispersant solution or the remover solution is 125 to 375 r/min.

4. The method for evaluating the dispersing and removing effects of the carbonaceous asphalt in the carbonate reservoir according to claim 3, wherein the stirring time for stirring and mixing the carbonaceous asphalt with the dispersant solution or the remover solution is 10 to 45 minutes.

5. The method for evaluating the dispersing and removing effect of carbonaceous asphalt in a carbonate reservoir according to claim 1, wherein when the suspension is subjected to turbidity and particle size tests, a liquid in the middle of the suspension is extracted for the test.

6. The method for evaluating the dispersing and removing effect of the carbonaceous asphalt in the carbonate reservoir according to claim 1, further comprising the steps of: weighing carbonaceous asphalt with the same initial mass, preparing a comparative suspension by adopting clear water, carrying out a comparative experiment, and calculating the dispersion value lambda of the carbonaceous asphalt under the action of the clear water₀And removal rate η₀。

7. The method for evaluating the dispersing and removing effect of the carbonaceous asphalt in the carbonate reservoir according to any one of claims 1 to 6, wherein the dispersion value λ is calculated by the following method:

λ＝N/D (1)

in the formula: λ is the dispersion value, NTU/μm; n is turbidity, NTU; d is the particle size, μm.

8. The method for evaluating the dispersing and removing effect of the carbonaceous asphalt in the carbonate reservoir according to any one of claims 1 to 6, wherein the removing rate η is calculated by the following method:

wherein η is the removal rate,%, M is the initial mass of the carbonaceous asphalt, g, and M is the residual mass of the carbonaceous asphalt, g.