Method for increasing production and injection of reservoir coupled with flue gas desulfurization and denitrification

Abstract

The last sentence of the abstract has been deleted because it refers to purported merits of the invention. The abstract should not refer to purported merits or speculative applications of the invention and should not compare the invention with the prior art, therefore the abstract has been amended to delete the last sentence by Examiner's amendment.

Claims

1. A method for increasing production and injection of a carbonate reservoir coupled with flue gas desulfurization and denitrification, characterized in that: a desulfurizing and denitrating agent is mixed uniformly with H.sub.2O.sub.2 solution to prepare a solution, and the solution is sprayed into a flue gas in an opposite direction of flue gas flow to obtain a waste liquor; or O.sub.3 is mixed into the flue gas in the opposite direction of flue gas flow, and simultaneously the desulfurizing and denitrating agent is sprayed into the flue gas to obtain the waste liquor; when the pH of the solution system reaches 6 to 6.5, the waste liquor is collected as an acid liquor and injected into a reservoir to increase production and injection thereof; the desulfurizing and denitrating agent comprises Tetrahydroxyethyl Ethylenediamine (THEED) or 2,2-Bipyridine (bipy) solution with a mass fraction of 0.010% to 0.025%.

2. The method for increasing production and injection of a carbonate reservoir coupled with flue gas desulfurization and denitrification according to claim 1, characterized in that the desulfurizing and denitrating agent is THEED solution with a mass fraction of 0.020% or bipy solution with a mass fraction of 0.020%.

3. The method for increasing production and injection of a carbonate reservoir coupled with flue gas desulfurization and denitrification according to claim 1, characterized in that the H.sub.2O.sub.2 solution has a mass fraction of 10% to 25%.

4. The method for increasing production and injection of a carbonate reservoir coupled with flue gas desulfurization and denitrification according to claim 3, characterized in that the H.sub.2O.sub.2 solution has a mass fraction of 15%.

5. The method for increasing production and injection of a carbonate reservoir coupled with flue gas desulfurization and denitrification according to claim 1, characterized in that a volume ratio of THEED solution with a mass fraction of 0.015% to H.sub.2O.sub.2 solution with a mass fraction of 15% is 100:1 to 200:1; a volume ratio of bipy solution with a mass fraction of 0.015% to the H.sub.2O.sub.2 solution with a mass fraction of 15% is 100:1 to 200:1; and a volume ratio of THEED or bipy with a mass fraction of 0.015% to O.sub.3 is 200:3 to 400:3.

6. The method for increasing production and injection of a carbonate reservoir coupled with flue gas desulfurization and denitrification according to claim 5, characterized in that a volume ratio of the bipy solution with a mass fraction of 0.015% to the H.sub.2O.sub.2 solution with a mass fraction of 15% is 400:3.

7. The method for increasing production and injection of a carbonate reservoir coupled with flue gas desulfurization and denitrification according to claim 5, characterized in that a volume ratio of the THEED or bipy with a mass fraction of 0.015% to the O.sub.3 is 100:1.

8. The method for increasing production and injection of a carbonate reservoir coupled with flue gas desulfurization and denitrification according to claim 1, characterized in that a volume ratio of the THEED solution with a mass fraction of 0.015% to H.sub.2O.sub.2 solution with a mass fraction of 15% is 75:1.

9. The method for increasing production and injection of a carbonate reservoir coupled with flue gas desulfurization and denitrification according to claim 1, characterized in that chemical reaction equations of the flue gas desulfurization and denitrification are: $\begin{array}{cc}2{\mathrm{NO}}_x+\left(5-2x\right)H_2{O}_2+\mathrm{bipy}={\left[H_2\mathrm{bipy}\right]}^{2+}+2{\mathrm{NO}}_3^{-}+\left(4-2x\right)H_{2}O& \left(1\right)\end{array}$ $\begin{array}{cc}{\mathrm{SO}}_x+\left(3-x\right)H_2{O}_2+\mathrm{THEED}={\left[H_2\mathrm{THEED}\right]}^{2+}+{\mathrm{SO}}_4^{2-}+\left(2-x\right)H_{2}O& \left(2\right)\end{array}$ $\begin{array}{cc}2{\mathrm{NO}}_x+\left(5-2x\right)O_3+\mathrm{THEED}+H_{2}O={\left[H_2\mathrm{THEED}\right]}^{2+}+2{\mathrm{NO}}_3^{-}+\left(5-2x\right)O_2& \left(3\right)\end{array}$ $\begin{array}{cc}{\mathrm{SO}}_x+\left(3-x\right)O_3+\mathrm{bipy}+H_{2}O={\left[H_2\mathrm{bipy}\right]}^{2+}+{\mathrm{SO}}_4^{2-}+\left(3-x\right)O_2.& \left(4\right)\end{array}$

10. The method for increasing production and injection of a carbonate reservoir coupled with flue gas desulfurization and denitrification according to claim 1, characterized in that chemical equations of the acid liquor being injected into the reservoir to increase production and injection thereof are: $\begin{array}{cc}{\mathrm{CaCO}}_3+{\left[H_2\mathrm{bipy}\right]}^{2+}={\left[\mathrm{Ca}\mathrm{bipy}\right]}^{2+}+{\mathrm{CO}}_2+H_{2}O& \left(5\right)\end{array}$ $\begin{array}{cc}{\mathrm{MgCO}}_3+{\left[H_2\mathrm{THEED}\right]}^{2+}={\left[\mathrm{Mg}\mathrm{THEED}\right]}^{2+}+{\mathrm{CO}}_2+H_{2}O.& \left(6\right)\end{array}$

11. The method for increasing production and injection of a carbonate reservoir coupled with flue gas desulfurization and denitrification according to claim 1, characterized in that acid injection rate of flow of the acid liquor into the reservoir is (0.5 to 5.0) m.sup.3/h.

12. The method for increasing production and injection of a carbonate reservoir coupled with flue gas desulfurization and denitrification according to claim 1, characterized in that the acid liquor contains a nitrate of the desulfurizing and denitrating agent with a mass fraction of 0.002% to 0.004% and a sulfate of the desulfurizing and denitrating agent with a mass fraction of 0.016% to 0.018%.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a graph showing variation of water injection pressure and water injection rate in C-2 water injection well of the S oil field of Application Example 2 from 2018 to 2021.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(2) The present disclosure will be explained in details with reference to the following specific examples, but is not limited thereto.

(3) It should be noted that the experimental methods described in the following examples are traditional methods unless otherwise specified. And the reagents, materials and equipment are commercially available unless otherwise specified.

Example 1

(4) A method for increasing production and injection of a reservoir coupled with flue gas desulfurization and denitrification includes the following steps: (1) Flue gas desulfurization and denitrification process: THEED with a mass fraction of 0.015% is added into H.sub.2O.sub.2 solution with a mass fraction of 15% to prepare a mixed solution, with a volume ratio of 75:1, and the mixed solution is sprayed into a flue gas in an opposite direction of flue gas flow, and when the pH of the system reaches 6.5, the waste liquor generated by desulfurization and denitrification is collected, which is the acid liquor. (2) The obtained acid liquor, with about 0.015% [H.sub.2THEED].sup.2+, may be directly injected into a formation to increase production and injection, and dissolution rate and corrosion rate of acid liquor are tested according to SY/T 5358-2002 Reservoir Sensitive Flow Test Method. The operation steps for testing the dissolution rate and corrosion rate of cuttings in different acid systems are as follows: 5 g of cuttings are respectively placed into test tubes containing 500 mL acid liquor, and then the test tubes are placed into a 90 C. water bath to fully react for 120 minutes and filter, so as to obtain the dissolution rate of cuttings. The hanging piece is descaled, degreased, dried, weighed, and immersed into the acid liquor using hanging piece weight loss method, and after 120 minutes, the hanging piece is fished out, the residual acid is washed, dried and weighed, and the corrosion rate is obtained. The results are shown in Table 1.

Example 2

(5) A method for increasing production and injection of a reservoir coupled with flue gas desulfurization and denitrification includes the following steps: (1) Flue gas desulfurization and denitrification process: bipy with a mass fraction of 0.015% is added into H.sub.2O.sub.2 solution with a mass fraction of 15% to prepare a mixed solution, with a volume ratio of 400:3, and the mixed solution is sprayed into a flue gas in an opposite direction of flue gas flow, and when the pH of the system reaches 6.5, the waste liquor generated by desulfurization and denitrification is collected, which is the acid liquor. (2) The obtained acid liquor, with about 0.015% [H.sub.2bipy].sup.2+, may be directly injected into a formation to increase production and injection, and dissolution rate and corrosion rate of the acid liquor are tested according to the method of Example 1. The results are shown in Table 1.

Example 3

(6) A method for increasing production and injection of a reservoir coupled with flue gas desulfurization and denitrification includes the following steps: (1) Flue gas desulfurization and denitrification process: O.sub.3 is mixed into a flue gas in an opposite direction of flue gas flow, and 0.015% THEED is sprayed at the same time, with a volume ratio of THEED to O.sub.3 being 100:1, and when the pH of the solution reaches 6.5, the waste liquor generated by desulfurization and denitrification is collected, which is the acid liquor. (2) The obtained acid liquor, with about 0.015% [H.sub.2THEED].sup.2+, may be directly injected into a formation to increase production and injection, and dissolution rate and corrosion rate of the acid liquor are tested according to the method of Example 1. The results are shown in Table 1.

Example 4

(7) A method for increasing production and injection of a reservoir coupled with flue gas desulfurization and denitrification includes the following steps: (1) Flue gas desulfurization and denitrification process: O.sub.3 is mixed into a flue gas in an opposite direction of flue gas flow, and bipy with a mass fraction of 0.015% is sprayed at the same time, with a volume ratio of O.sub.3 to bipy being 1:100, and when the pH of the solution reaches 6.5, the waste liquor generated by desulfurization and denitrification is collected, which is the acid liquor. (2) The obtained acid liquor, with about 0.015% [H.sub.2bipy].sup.2+, may be directly injected into a formation to increase production and injection, and dissolution rate and corrosion rate of the acid liquor are tested according to the method of Example 1. The results are shown in Table 1.

Comparative Example 1

(8) The dissolution rate and corrosion rate of hydrochloric acid with a mass fraction of 15% are tested according to the method of Example 1, and the results are shown in Table 1.

Comparative Example 2

(9) The dissolution rate and corrosion rate of traditional nitric acid powdered acid containing urea nitrate (with a mass fraction of 15%) are tested according to the method of Example 1, and the results are shown in Table 1.

(10) TABLE-US-00001 TABLE 1 Dissolution rate and corrosion rate of cuttings in different acid liquor systems Acid liquor system Dissolution rate/% Corrosion rate/% Comparative Example 1 11.05 0.75 Comparative Example 2 22.03 1.18 Example 1 40.50 0.64 Example 2 30.07 0.59 Example 3 40.70 0.65 Example 4 30.09 0.60

(11) It can be seen from Table 1 that in Example 1, THEED is used to replace a traditional curing agent, whose dissolution rate is 2 times higher than that of the above-mentioned traditional powdered nitric acid and nearly 4 times higher than that of HCl, and whose corrosion rate is 55% of that of traditional powdered nitric acid and 87% of that of HCl. In Example 2, bipy is used to replace a traditional curing agent, whose dissolution rate is 1.5 times higher than that of traditional powdered nitric acid and nearly 3 times higher than that of HCl, and whose corrosion rate is 50% of that of traditional powdered nitric acid and 80% of that of HCl. In Example 3, THEED is used to replace a traditional curing agent, whose dissolution rate is 2 times higher than that of traditional powdered nitric acid and nearly 4 times higher than that of HCl, and whose corrosion rate is 55% of that of traditional powdered nitric acid and 87% of that of HCl. In Example 4, bipy is used to replace a traditional curing agent, whose dissolution rate is 1.5 times higher than that of traditional powdered nitric acid and nearly 3 times higher than that of HCl, and whose corrosion rate is 50% of that of traditional powdered nitric acid and 80% of that of HCl.

(12) The acid liquor according to the present disclosure is better than traditional powdered acids in increase of production and injection and corrosion inhibition properties: THEED is used to replace a traditional curing agent, because it has a strong alkalinity and a longer acting distance of acid liquor, and is easily coordinated with Ca.sup.2+ and Mg.sup.2+ than bipy, showing a better performance of increasing production and injection. Bipy is used as a curing agent, because it is easily coordinated with Fe.sup.3+ and adsorbed on pipeline surface, showing a better corrosion inhibition performance.

Example 5

(13) Different concentrations of THEED curing agent are used to desulfurize and denitrify flue gas of the same mass, where oxidation system is H.sub.2O.sub.2 solution (with a mass fraction of 15%), and NO.sub.x and SO.sub.x have a concentration of 0.8% and 1.6% respectively. The waste liquor of desulfurization and denitrification process is directly used as acid liquor, and then the dissolution rate and corrosion rate of rock cuttings are evaluated by the method of Example 1. The results are shown in Table 2. As can be seen, curing agent concentration is preferably 0.020%. Although corrosion inhibition performance increases with the increase of curing agent concentration, when the curing agent concentration is 0.025%, the solution has weak acidity and poor performance of increasing production and injection, so the optimal curing agent concentration is 0.020%.

(14) TABLE-US-00002 TABLE 2 Dissolution rate and corrosion rate of acid liquors prepared by different THEED concentrations on cuttings Curing agent concentration/% Dissolution rate/% Corrosion rate/% 0.010 38.23 0.68 0.015 40.50 0.64 0.020 41.02 0.59 0.025 38.66 0.54

Example 6

(15) Different concentrations of bipy curing agent are used to desulfurize and denitrify flue gas of the same mass in Example 5, where oxidation system is H.sub.2O.sub.2 solution (with a mass fraction of 15%), and NO.sub.x and SO.sub.x have a concentration of 0.8% and 1.6% respectively. The waste liquor of desulfurization and denitrification process is directly used as acid liquor, and then the dissolution rate and corrosion rate of rock cuttings are evaluated by the method of Example 1. The results are shown in Table 3. As can be seen, curing agent concentration is preferably 0.020%. Although corrosion inhibition performance increases with the increase of curing agent concentration, when the curing agent concentration is 0.025%, the solution has weak acidity and poor performance of increasing production and injection, so the optimal curing agent concentration is 0.020%.

(16) TABLE-US-00003 TABLE 3 Dissolution rate and corrosion rate of acid liquors prepared by different bipy concentrations on cuttings Curing agent concentration/% Dissolution rate/% Corrosion rate/% 0.010 28.14 0.66 0.015 30.07 0.59 0.020 36.52 0.56 0.025 33.64 0.51

Application Example 1

(17) In 2020, H.sub.2O.sub.2 and bipy curing agent were successfully applied to flue gas desulfurization and denitrification in P thermal power plant of T oil field, which had been using the SCR method for desulfurization and denitrification before. Now different volume ratios of H.sub.2O.sub.2 and bipy are prepared as curing agent to make the flue gas pass through the curing agent. Desulfurization and denitrification efficiency is obtained by determining concentrations of NO.sub.x and SO.sub.x before and after the flue gas passing through the curing agent through gas chromatography, as shown in Table 4, and mass fractions of sulfate and nitrate in waste liquor of desulfurization and denitrification are determined through liquid chromatography. It can be seen that desulfurization and denitrification efficiency of the curing agent is higher than that of the SCR method, and water eutrophication is treated. The volume ratio of bipy to H.sub.2O.sub.2 is preferably 400:3, at which the waste liquor contains a nitrate of the desulfurizing and denitrating agent with a mass fraction of 0.004% and a sulfate of the desulfurizing and denitrating agent with a mass fraction of 0.018%. When the volume ratio is relatively low, NO.sub.x cannot be oxidized sufficiently, and is difficult to continue to react with bipy. When the volume ratio is relatively high, the generated H.sub.2SO.sub.4 and HNO.sub.3 are not completely neutralized, so the desulfurization and denitrification efficiency is low.

(18) TABLE-US-00004 TABLE 4 Desulfurization and denitrification efficiency of curing agents prepared with different volume ratios of H.sub.2O.sub.2 to bipy Desulfurization Denitrification Methods efficiency/% efficiency/% SCR method 79.09 75.50 V(bipy):V(H.sub.2O.sub.2) 50:1 80.03 76.65 in the present 100:1 88.33 86.45 disclosure 400:3 97.50 96.04 200:1 93.58 92.84

Application Example 2

(19) In 2019, H.sub.2O.sub.2 and THEED curing agent were successfully applied to flue gas desulfurization and denitrification in P thermal power plant of T oil field, which had been using the SCR method for desulfurization and denitrification before. Now different volume ratios of H.sub.2O.sub.2 and THEED are prepared as curing agent to make the flue gas pass through the curing agent. Desulfurization and denitrification efficiency is obtained by determining concentrations of NO.sub.x and SO.sub.x before and after the flue gas passing through the curing agent through gas chromatography, as shown in Table 5. The waste liquor produced by desulfurization and denitrification is collected, mass fractions of sulfate and nitrate of which are determined through liquid chromatography. It can be seen that the desulfurization and denitrification efficiency of THEED is higher than that of the SCR method and bipy due to its strong alkalinity, and water eutrophication is treated. The volume ratio of THEED to H.sub.2O.sub.2 is preferably 75:1, at which the waste liquor contains a nitrate of the desulfurizing and denitrating agent with a mass fraction of 0.002% and a sulfate of the desulfurizing and denitrating agent with a mass fraction of 0.016%.

(20) TABLE-US-00005 TABLE 5 Desulfurization and denitrification efficiency of curing agents prepared with different volume ratios of H.sub.2O.sub.2 to THEED Desulfurization Denitrification Methods efficiency/% efficiency/% SCR method 79.09 75.50 V(THEED):V(H.sub.2O.sub.2) 50:1 80.54 77.56 in the present 75:1 99.00 98.00 disclosure 100:1 91.23 89.85 200:1 95.51 94.34

Application Example 3

(21) On Mar. 8, 2018, powdered nitric acid (the main constituent is urea nitrate with a mass fraction of 15%) was used for acidizing and stimulation of C-2 injection well of the S oil field. After the construction, the water injection pressure dropped to 26 MPa, and the daily water injection rate rose to 87 m.sup.3/d, but the water injection pressure increased to 35 MPa after 210 days. On Feb. 3, 2019, the water injection pressure was 35 MPa and the daily water injection rate was 41 m.sup.3/d before the construction, and the waste liquor produced in the desulfurization and denitrification process of Example 2 was used for acidizing and stimulation with acid injection rate of flow being 5 m.sup.3/h. And the water injection pressure was 18 MPa after the construction and the daily water injection rate was 124 m.sup.3/d, as shown in FIG. 1, which is effective until now.