A composition, a plug removal system and a plug removal method

Abstract

The application provides a composition, a plugging removal system and a plugging removal method, the composition comprising sodium nitrite, a surfactant, sodium carbonate and ammonium hydrogen fluoride; the plugging removal system comprising a prepad, a gas generation agent, a spacer fluid, the composition and a displacement agent; and the plugging removal method comprising the following steps: sequentially injecting the prepad and the gas generation agent into a well; after 10 to 30 minutes, injecting the spacer fluid; after the injection of the spacer fluid is completed, after 10 to 30 minutes, sequentially injecting the composition and the displacement agent, and after reaction, opening the well and assisting in the removal by nitrogen.

Claims

1. A deblocking system comprising a pre-blocker, a composition, an aerator, a separator, and a displacement agent; The total mass of the pre-segment plug is taken as 100%, and the pre-segment plug includes 0.1% to 0.6% of a second surfactant, 0.1% to 0.4% of sodium carbonate, 0.1% to 0.8% of a first anti-swelling agent, and the balance being water; The composition comprises sodium nitrite, a first surfactant, sodium carbonate, and ammonium bifluoride; The total mass of the gas-generating agent is 100%, and the gas-generating agent includes 7% to 10% urea, 0.5% to 1.5% scale inhibitor, 7% to 11% hydrochloric acid, 1.0% to 1.9% corrosion inhibitor, 0.7% to 1.2% iron ion stabilizer, 1.6% to 2.5% acid slag inhibitor, 0.1% to 0.7% second anti-swelling agent, and the balance being water; The first surfactant is a first betaine-type surfactant; the first betaine-type surfactant is sulfopropyl betaine, sulfate betaine, phosphate betaine, C 12 To C 18 Alkyl betaine and C 12 To C 18 At least one of the alkylamide betaine; The second surfactant is a second betaine-type surfactant; the second betaine-type surfactant is sulfopropyl betaine, sulfate betaine, phosphate betaine, C 12 To C 18 Alkyl betaine and C 12 To C 18 At least one of the alkylamide betaine; The first anti-swelling agent and the second anti-swelling agent independently comprise 10 to 65 parts by weight of an alkyl hydroxypropyl quaternary ammonium salt, 1 to 10 parts by weight of guanidine hydrochloride, and 1 to 10 parts by weight of a nonionic surfactant; wherein the nonionic surfactant is at least one selected from OP-4, OP-6, OP-7, OP-10, OP-15, OP-20, TX-10, and AEO-3; The scale inhibitor is at least one of aminotrimethylenephosphonic acid, ethylenediaminetetramethylenephosphonic acid, and sodium ethylenediaminetetramethylene phosphate. The iron ion stabilizer comprises 1.5 to 5 parts by weight of an iron complexing agent and 0.8 to 1.2 parts by weight of an iron reducing agent; the iron complexing agent is at least one selected from sodium ethylenediaminetetramethylene phosphate, ethylenediaminetetramethylenephosphonic acid, sodium ethylenediaminetetraacetic acid, and sodium hexametaphosphate; the iron reducing agent is at least one selected from copper powder, zinc powder, and phosphorus tribromide. The acid-resistant slag agent comprises 10 to 20 parts by weight of ethylene glycol monobutyl ether and 0.8 to 1.2 parts by weight of ammonium chloride.

2. The unblocking system according to claim 1, characterized in that, The total mass of the composition is 100%, and the composition comprises 6% to 12% sodium nitrite, 0.1% to 0.6% of the first surfactant, 0.1% to 0.4% of sodium carbonate, 6% to 12% of ammonium bifluoride, and the balance being water.

3. The unblocking system according to claim 2, characterized in that, The total mass of the composition is 100%, and the composition comprises 8% to 10% sodium nitrite, 0.2% to 0.3% of the first surfactant, 0.25% to 0.3% sodium carbonate, 8% to 10% ammonium bifluoride, and the balance being water; The mass ratio of the first surfactant to the sodium carbonate is (1 to 2):

1.

4. The unblocking system according to claim 1, characterized in that, The total mass of the pre-segment plug is taken as 100%, and the pre-segment plug includes 0.15% to 0.55% of the second surfactant, 0.12% to 0.35% of the sodium carbonate, 0.15% to 0.75% of the first anti-swelling agent, and the balance being water; The total mass of the gas-generating agent is 100%, and the gas-generating agent includes 8.5% to 9.5% of the urea, 0.8% to 1.2% of the scale inhibitor, 8% to 10% of the hydrochloric acid, 1.3% to 1.6% of the corrosion inhibitor, 0.9% to 1.1% of the iron ion stabilizer, 1.8% to 2.2% of the acid slag inhibitor, 0.4% to 0.6% of the second anti-swelling agent, and the balance being water.

5. The unblocking system according to claim 4, characterized in that, The total mass of the pre-segment plug is taken as 100%, and the pre-segment plug includes 0.4% to 0.55% of the second surfactant, 0.12% to 0.25% of the sodium carbonate, 0.15% to 0.4% of the first anti-swelling agent, and the balance being water; the mass ratio of the second surfactant to the sodium carbonate is 1:(0.2 to 2.33); The total mass of the gas-generating agent is 100%, and the gas-generating agent includes 9% urea, 1% scale inhibitor, 9% hydrochloric acid, 1.5% corrosion inhibitor, 1% iron ion stabilizer, 2% acid slag inhibitor, 0.5% second anti-swelling agent, and the balance being water.

6. The unblocking system according to claim 1, characterized in that, The hydrochloric acid is a 10wt% to 15wt% aqueous solution of hydrogen chloride; The acid-resistant slag agent comprises 11.5 to 15 parts by weight of ethylene glycol monobutyl ether and 0.8 to 1.2 parts by weight of ammonium chloride; The alkyl hydroxypropyl quaternary ammonium salt is a dodecyl hydroxypropyl quaternary ammonium salt and / or a docosyl hydroxypropyl quaternary ammonium salt.

7. The unblocking system according to claim 1, characterized in that, The isolation fluid is water; the displacement agent is formation water.

8. A method for unblocking using the unblocking system as described in any one of claims 1 to 7, comprising the following steps: 1) Inject the pre-plug and the gas-generating agent into the well in sequence; 2) After the first time interval, inject the isolation fluid into the well; 3) After a second time interval, the composition and the displacement agent are injected into the well sequentially; 4) After the third time of shut-in reaction, nitrogen gas is introduced into the well for the fourth time to assist in drainage.

9. The unblocking method according to claim 8, characterized in that, The injection volume of the pre-block plug is 200m. 3 up to 800m 3 ; and / or The injection volume of the propellant and the injection volume of the composition are independently 10 mg / L. 3 up to 50m 3 ; and / or The injection volume of the isolation fluid is 1m. 3 Up to 10m 3 ; and / or The injection volume of the displacement agent is 100 mg / L. 3 up to 400m 3 .

10. The unblocking method according to claim 8 or 9, characterized in that, The first duration and the second duration are independently 10 min to 30 min; and / or The third and fourth durations are independently 24 hours to 72 hours; and / or The injection rate of the unblocking system is 200 L / min to 400 L / min; and / or The nitrogen gas is introduced at a rate of 2000 to 6000 standard m / s. 3 / h.

11. The application of the unblocking system according to any one of claims 1 to 7 or the unblocking method according to any one of claims 8 to 10 in reservoir unblocking.

12. The application according to claim 11, characterized in that, The application is in the unblocking of clastic rock reservoirs.