Diverting acid for carbonate rock stratum
By using steering acid prepared by methylsulfonic acid, inorganic hydrochloric acid and distilled water in the acidification and production transformation of oil fields, the problem of uneven injection of acid is solved, and the uniform distribution and effective steering of acid in carbonate formations is achieved, satisfying the satisfaction of satisfying the The demand for acidification treatment in oil fields.
Patent Information
- Application Number
- CN202411257377.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-09
- Publication Date
- 2025-01-03
AI Technical Summary
In the transformation of acidification and production of oil fields, the heterogeneity of carbonate formations leads to uneven injection of acid liquid, and it is impossible to effectively treat areas with low permeability, resulting in an increase in the gap in the permeability of the formation and intensification of contradictions within and between layers. Chemical steering technology has its advantages and disadvantages, and it is difficult to accurately place the acid solution.
The steering acid prepared in a specific proportion of methylsulfonic acid, inorganic hydrochloric acid and distilled water is used to realize the steering and slowing effect of the acid liquid by reacting with the carbonate rock to ensure the effective distribution of the acid liquid in the carbonate rock formation.
The uniform distribution of acid liquid is achieved, which can effectively break down the core of low permeability, avoid damage to the formation, and meet the uniform treatment needs of carbonate formations.
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Abstract
Description
Technical Field
[0001] The invention relates to the technical field of oil field acidification production enhancement and transformation, in particular to a diverting acid used for carbonate rock formations. Background Art
[0002] In oilfield production technology, acidizing and production enhancement is an important technology. Due to the heterogeneity of carbonate reservoirs, after the acid is injected into the formation, it will follow the principle of least resistance, bypassing the area with low permeability and severe damage, and enter the area with high permeability and less damage, which will eventually cause most of the acid to flow into a small number of pore throats, while the contaminated areas are not effectively treated, resulting in a widening of the permeability gap in the formation and intensified conflicts within and between layers. Therefore, when performing acidizing treatment, the core issue is how to effectively and accurately place the acid in the target layer, which is directly related to the success or failure of the acidizing operation. In order to achieve uniform treatment of the formation, the acid must be diverted.
[0003] At present, there are several types of chemical diversion methods: (1) polymer diversion technology (2) supersaturated brine to form precipitation particles (3) foam diversion technology (4) surfactant self-diversion technology. Each of the above chemical diversion technologies has its own advantages and disadvantages. Summary of the invention
[0004] The purpose of the present invention is to provide a diverting acid for carbonate formations in view of the above-mentioned defects in the prior art, which can not only react with carbonate rocks to play the role of the main acid system, but also effectively divert the acid, and at the same time it can also play a retarding role.
[0005] The present invention mentions a diverting acid for carbonate formations, and its technical solution is: the following mass ratio concentration, weight parts: The method is prepared by mixing an organic compound strong acid, an inorganic hydrochloric acid and distilled water in a certain proportion, wherein the organic compound strong acid is 33-47 parts of methanesulfonic acid, and the concentration of methanesulfonic acid is 70% or 99%; the concentration of the inorganic hydrochloric acid is 31%, and the concentration is 43-58 parts, and the distilled water is 9-10 parts.
[0006] The present invention provides a diverting acid for carbonate formations, and the preparation method thereof comprises the following steps: the following mass ratio concentrations are obtained: (1) At room temperature, 10 parts by weight of distilled water and 43 parts by weight of 31% hydrochloric acid were added to a reaction kettle in sequence, and stirred at 1500 rpm for 1 minute; (2) adding 47 parts by weight of 70% methanesulfonic acid and stirring at 1500 rpm for 3 minutes; (3) Leave the prepared liquid in the steering fluid storage tank.
[0007] The present invention provides a diverting acid for carbonate formations, and the preparation method thereof comprises the following steps: the following mass ratio concentrations are obtained: (1) At room temperature, 9 parts by weight of distilled water and 58 parts by weight of 31% hydrochloric acid were added to a reaction kettle in sequence, and stirred at 1500 rpm for 1 minute; (2) adding 33 parts by weight of 99% methanesulfonic acid and stirring at 1500 rpm for 3 minutes; (3) Leave the prepared liquid in the steering fluid storage tank.
[0008] Compared with the prior art, the beneficial effects of the present invention are as follows: The methanesulfonic acid used in the present invention can react with carbonate rock to serve as the main acid solution system; the methanesulfonic acid can effectively realize the acid solution diversion; in addition, in the carbonate rock formation, the methanesulfonic acid can play a retarding role after being added with hydrochloric acid; therefore, the methanesulfonic acid used in the present invention plays a three-purpose effect in the hydrochloric acid solution, and can meet the demand for effective diversion of the carbonate rock formation. DETAILED DESCRIPTION
[0009] The preferred embodiments of the present invention are described below. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.
[0010] Example 1: A diverting acid for carbonate formations mentioned in the present invention is prepared by the following steps: The following concentrations are expressed in mass percentages and in parts by weight: (1) At room temperature, 10 parts by weight of distilled water and 43 parts by weight of 31% hydrochloric acid were added to a reaction kettle in sequence, and stirred at 1500 rpm for 1 minute; (2) adding 47 parts by weight of 70% methanesulfonic acid and stirring at 1500 rpm for 3 minutes; (3) Place the prepared liquid in a liquid storage tank; (4) Add calcium carbonate to the above solution to react and observe the changes in the solution; (5) If solid product precipitates, add 15% hydrochloric acid to the mixture and observe the changes in the solution; (6) Repeat the above experiment at a temperature of 80°C.
[0011] Comparative experiment 1-1: (1) At room temperature, 57 parts by weight of distilled water and 43 parts by weight of 31% hydrochloric acid were added to a reaction kettle in sequence, and stirred at 1500 rpm for 1 minute; (2) Place the prepared hydrochloric acid solution in a storage tank; (3) Add calcium carbonate to the above solution to react and observe the changes in the solution; (4) If solid product precipitates, add 15% hydrochloric acid to the mixture and observe the changes in the solution; (5) Repeat the above experiment at a temperature of 80°C.
[0012] Example 2: A diverting acid for carbonate formations mentioned in the present invention is prepared by the following steps: The following mass percentage concentrations are in parts by weight: (1) At room temperature, 10 parts by weight of distilled water and 43 parts by weight of 31% hydrochloric acid were added to a reaction kettle in sequence, and stirred at 1500 rpm for 1 minute; (2) adding 47 parts by weight of 70% methanesulfonic acid and stirring at 1500 rpm for 3 minutes; (3) Place the prepared liquid in a liquid storage tank; (4) Place two cores with different permeabilities in the dual core flowmeter device, one with a permeability of 1 mD and the other with a permeability of 10 mD, and preheat them to 80°C. Inject the ammonium chloride solution and the prepared acid solution into the intermediate container, start the displacement pump, first displace the ammonium chloride solution at a rate of 1 mL / min, and then displace the acid solution after the pressure stabilizes. Observe the pressure change and whether the low permeability core of 1 mD is penetrated by the acid solution, and record the breakthrough volume.
[0013] Comparative experiment 2-1: (1) At room temperature, 57 parts by weight of distilled water and 43 parts by weight of 31% hydrochloric acid were added to a reaction kettle in sequence, and stirred at 1500 rpm for 1 minute; (2) Place the prepared hydrochloric acid solution in a storage tank; (3) Place two cores with different permeabilities in the dual core flowmeter device, one with a permeability of 1 mD and the other with a permeability of 10 mD, and preheat them to 80°C. Inject the ammonium chloride solution and the prepared acid solution into the intermediate container, start the displacement pump, first displace the ammonium chloride solution at a rate of 1 mL / min, and then displace the acid solution after the pressure stabilizes. Observe the pressure change and whether the low permeability core of 1 mD is penetrated by the acid solution, and record the breakthrough volume.
[0014] Example 3: A diverting acid for carbonate formations mentioned in the present invention is prepared by the following steps: The following mass percentage concentrations are in parts by weight: (1) At room temperature, 9 parts by weight of distilled water and 58 parts by weight of 31% hydrochloric acid were added to a reaction kettle in sequence, and stirred at 1500 rpm for 1 minute; (2) adding 33 parts by weight of 99% methanesulfonic acid and stirring at 1500 rpm for 3 minutes; (3) Place the prepared liquid in a liquid storage tank; (4) Add calcium carbonate to the above solution to react and observe the changes in the solution; (5) If solid product precipitates, add 20% hydrochloric acid to the mixture and observe the changes in the solution; (6) Repeat the above experiment at a temperature of 80°C.
[0015] Comparative experiment 3-1: (1) At room temperature, 42 parts by weight of distilled water and 58 parts by weight of 31% hydrochloric acid were added to a reaction kettle in sequence, and stirred at 1500 rpm for 1 minute; (2) Place the prepared hydrochloric acid solution in a storage tank; (3) Add calcium carbonate to the above solution to react and observe the changes in the solution; (4) If solid product precipitates, add 20% hydrochloric acid to the mixture and observe the changes in the solution; (5) Repeat the above experiment at a temperature of 80°C.
[0016] Example 4: A diverting acid for carbonate formations mentioned in the present invention is prepared by the following steps: The following mass percentage concentrations are in parts by weight: (1) At room temperature, 9 parts by weight of distilled water and 58 parts by weight of 31% hydrochloric acid were added to a reaction kettle in sequence, and stirred at 1500 rpm for 1 minute; (2) adding 33 parts by weight of 99% methanesulfonic acid and stirring at 1500 rpm for 3 minutes; (3) Place the prepared liquid in a liquid storage tank; (4) Place two cores with different permeabilities in the dual core flowmeter device, one with a permeability of 1 mD and the other with a permeability of 10 mD, and preheat them to 80°C. Inject the ammonium chloride solution and the prepared acid solution into the intermediate container, start the displacement pump, first displace the ammonium chloride solution at a rate of 1 mL / min, and then displace the acid solution after the pressure stabilizes. Observe the pressure change and whether the low permeability core of 1 mD is penetrated by the acid solution, and record the breakthrough volume.
[0017] Comparative experiment 4-1: (1) At room temperature, 42 parts by weight of distilled water and 58 parts by weight of 31% hydrochloric acid were added to a reaction kettle in sequence, and stirred at 1500 rpm for 1 minute; (2) Place the prepared hydrochloric acid solution in a storage tank; (3) Place two cores with different permeabilities in the dual core flowmeter device, one with a permeability of 1 mD and the other with a permeability of 10 mD, and preheat them to 80°C. Inject the ammonium chloride solution and the prepared acid solution into the intermediate container, start the displacement pump, first displace the ammonium chloride solution at a rate of 1 mL / min, and then displace the acid solution after the pressure stabilizes. Observe the pressure change and whether the low permeability core of 1 mD is penetrated by the acid solution, and record the breakthrough volume.
[0018] At room temperature and 80°C, calcium carbonate is added to the acid solution. As the pH value increases, solid particles precipitate from the solution. After being diluted by the hydrochloric acid solution, the solid product dissolves into the solution again. At 80°C, the acid solution is displaced by a dual core flow meter. The acid solution containing methanesulfonic acid can effectively penetrate the 1 mD low permeability core, while the acid solution without methanesulfonic acid cannot effectively penetrate the 1 mD low permeability core. Wherein the breakthrough volume = flow rate * breakthrough time / pore volume of the tested core sample. The diverting acid of the present invention can meet the demand for effective diversion of carbonate formations.
[0019] The performance test of the diverting acid for carbonate formation mentioned in the present invention is as follows: 1) The acid performance of Example 1 and Comparative Experiment 1-1 is shown in Table 1. The experimental data show that under the conditions of 25°C and 80°C, as calcium carbonate is added, calcium carbonate reacts with the acid solution, the pH value of the solution increases, and solid particles precipitate from the solution. Subsequently, 15% hydrochloric acid solution is used for dilution, and the solid product dissolves in the solution again.
[0020] Table 1
[0021] 2) The acid performance of Example 2 and Comparative Experiment 2-1 is shown in Table 2. The experimental data show that at 80°C, The acid solution containing methanesulfonic acid can effectively penetrate both the 1 mD low permeability core and the 10 mD high permeability core, with a breakthrough volume of 0.55-0.67 PV. However, the acid solution without methanesulfonic acid cannot effectively penetrate the 1 mD low permeability core, but can only penetrate the 10 mD high permeability core.
[0022] Table 2
[0023] 3) The acid performance of Example 3 and Comparative Experiment 3-1 is shown in Table 3. The experimental data show that under the conditions of 25°C and 80°C, as calcium carbonate is added, calcium carbonate reacts with the acid solution, the pH value of the solution increases, and solid particles precipitate from the solution. Subsequently, 20% hydrochloric acid solution is used for dilution, and the solid product dissolves in the solution again.
[0024] Table 3
[0025] 4) The acid performance of Example 4 and Comparative Experiment 4-1 is shown in Table 4. The experimental data show that at 80°C, The acid solution containing methanesulfonic acid can effectively penetrate both the 1 mD low permeability core and the 10 mD high permeability core, with a breakthrough volume of 0.46-0.59 PV. However, the acid solution without methanesulfonic acid cannot effectively penetrate the 1 mD low permeability core, but can only penetrate the 10 mD high permeability core.
[0026] Table 4
[0027] It can be seen from the performance evaluation data in Tables 1 and 3 that methanesulfonic acid has excellent solubility in hydrochloric acid. When the acid reacts with calcium carbonate to increase the pH value of the residual acid solution, the generated calcium methanesulfonate will precipitate from the solution, and solid particles will precipitate and block the rock pores in the high permeability layer, thereby achieving the diversion of the acid. The precipitated calcium methanesulfonate can be diluted and dissolved by the subsequent acid, thereby avoiding damage to the formation.
[0028] It can be seen from the performance evaluation data in Table 2 and Table 4 that when displacing acid in the dual core flow meter, as the reaction proceeds, the acid containing methanesulfonic acid can form precipitation, and the precipitated solid particles can block the pores of the 10 mD high permeability core, thereby diverting the acid to the pores of the 1 mD low permeability core, achieving effective penetration of two cores with different permeabilities at the same time. However, the acid without methanesulfonic acid lacks this chemical mechanism and cannot effectively penetrate the 1 mD low permeability core, but can only penetrate the 10 mD high permeability core.
[0029] The above are only some preferred embodiments of the present invention. Any person skilled in the art may modify the above technical solutions or modify them into equivalent technical solutions. Therefore, the corresponding simple modifications or equivalent transformations made according to the technical solutions of the present invention shall fall within the scope of protection claimed by the present invention.
Claims
1. A diverting acid for carbonate formations, characterized by: By mass ratio concentration, parts by weight: The method is prepared by mixing an organic compound strong acid, an inorganic hydrochloric acid and distilled water in a certain proportion, wherein the organic compound strong acid is 33-47 parts of methanesulfonic acid, and the concentration of methanesulfonic acid is 70% or 99%; the concentration of the inorganic hydrochloric acid is 31%, and the concentration is 43-58 parts, and the distilled water is 9-10 parts.
2. The diverting acid for carbonate formations according to claim 1, characterized in that: The preparation method of the diverting acid comprises the following steps: the following concentrations are prepared according to mass ratio: (1) At room temperature, 10 parts by weight of distilled water and 43 parts by weight of 31% hydrochloric acid were added to a reaction kettle in sequence, and stirred at 1500 rpm for 1 minute; (2) adding 47 parts by weight of 70% methanesulfonic acid and stirring at 1500 rpm for 3 minutes; (3) Leave the prepared liquid in the steering fluid storage tank.
3. The diverting acid for carbonate formations according to claim 1, characterized in that: The preparation method of the diverting acid comprises the following steps: the following concentrations are prepared according to mass ratio: (1) At room temperature, 9 parts by weight of distilled water and 58 parts by weight of 31% hydrochloric acid were added to a reaction kettle in sequence, and stirred at 1500 rpm for 1 minute; (2) adding 33 parts by weight of 99% methanesulfonic acid and stirring at 1500 rpm for 3 minutes; (3) Leave the prepared liquid in the steering fluid storage tank.