CN102877820A - A Method for Reducing Water Injection Pressure of Reservoir Water Wells - Google Patents

Abstract

The invention relates to a method for reducing the water injection pressure of a reservoir water well; replacing cleaning liquid with the liquid amount of 1-2 square, closing the well, reacting for 50min, cleaning impurities of a shaft, an oil pipe and an eyelet, and replacing residual acid with the shaft; secondly, injecting a first preposed acid slug with the liquid amount being 1 time of the volume of the shaft; the third step is to positively squeeze a second main acid slug, and the liquid amount is 2 times of the volume of the shaft; fourthly, positively extruding and injecting a third postposition acid slug, wherein the liquid amount is 2 times of the volume of the shaft; fifthly, positively extruding and injecting a fourth surfactant slug, wherein the liquid amount is 5-6 times of the volume of the shaft, the concentration of the surfactant is 0.15-0.05 percent, and the balance is clear water; the water injection pressure of the ultra-low-permeability compact water injection well is reduced through the comprehensive effect formed by different action mechanisms of the four slugs.

Description

A Method for Reducing Water Injection Pressure of Reservoir Water Wells

Technical field:

The invention relates to a method for reducing the water injection pressure of a water well in an ultra-low permeability tight reservoir.

Background technique:

At present, the Changqing ultra-low permeability reservoir has a wide development area, many development strata, and complex reservoir characteristics. Water injection is the key to the economical and effective development of ultra-low permeability reservoirs. In the process of large-scale production, it was found that some blocks had high water injection pressure, which could not meet the requirements of injection injection. Conventional single acidification stimulation techniques were adopted, such as conventional soil acid, retarded acid, continuous acid, self-generated weak acid, and polyhydric acid. Note that the effect is not obvious.

Invention content:

The purpose of the present invention is to provide a method for reducing the water injection pressure of reservoir water wells. Specifically, five steps are adopted to inject four different liquid slugs, and the combined effect formed by the different action mechanisms of the four slugs reduces the conventional increase. Water injection pressure of ultra-low permeability tight water injection wells where injection measures are difficult to be effective.

A method for reducing the water injection pressure of reservoir water wells according to the present invention, specifically, adopts five steps, injects four different liquid slugs, and reduces conventional injection enhancement measures through the comprehensive effect formed by the different functions of the four slugs. Injection pressure of a refractory injection well characterized by:

The first step is to replace the cleaning fluid, the liquid volume is 1-2 cubic meters, and the well is closed for 50 minutes to clean the wellbore, tubing and hole impurities, and the residual acid is replaced by the wellbore;

The second step is to inject the first pre-acid slug, and the liquid volume is 1 times the wellbore volume;

In the third step, the acid slug is injected into the second main body by positive extrusion, and the liquid volume is twice the volume of the wellbore;

The fourth step is to squeeze into the third post-acid slug, and the liquid volume is 2 times the wellbore volume;

The fifth step is to squeeze into the fourth ultra-low interfacial tension surfactant slug, the liquid volume is 5-6 times the wellbore volume, the surfactant concentration is 0.15%-0.05%, and the rest is clear water;

The cleaning solution is: 7-8% hydrochloric acid, 2-4% glacial acetic acid, 2-4% comprehensive additives, 2-4% ammonium chloride, and the rest is clear water.

The preceding acid is: 11-13% hydrochloric acid, 2-4% glacial acetic acid, 2-4% comprehensive additives, 2-4% ammonium chloride, and the rest is clear water.

The main acid is: 11-13% hydrochloric acid, 4-6% glacial acetic acid, 1-3% hydrofluoric acid, 2-4% comprehensive additives, 2-4% ammonium chloride, and the rest is clear water.

The post acid is: 11-13% hydrochloric acid, 2-4% glacial acetic acid, 2-4% comprehensive additives, 2-4% ammonium chloride, and the rest is clear water.

The preparation method of the ultra-low interfacial tension surfactant: select the low-condensation naphthenic decompression distillate oil in Xinjiang as raw material, sulfonate with gaseous sulfur trioxide; Put 500-650 grams of distillate oil into the reaction bottle, stir and heat up to 60°C, and weigh the required amount of liquid sulfur trioxide in another 500 ml three-necked bottle equipped with a thermometer. The mass ratio of oil and sulfur trioxide is 1:1.4, water bath heat preservation to control the production of sulfur trioxide gas; the air in the air cylinder is dried and measured by a gas flow meter, and then enters the sulfur trioxide bottle, and the sulfur trioxide is gradually blown out, and the blown gas is heated by the buffer bottle After heating up to 60-70°C, import it into the sulfonation reaction bottle until all the sulfur trioxide has reacted; continue to react at 60°C for half an hour, stop stirring; keep warm and settle for half an hour, release unreacted oil and petroleum sulfonic acid, and keep stirring at 60°C Neutralize to pH 7-7.5 with 20% sodium hydroxide aqueous solution by mass, add 300 ml of 50% ethanol/water solution by mass for extraction, obtain petroleum sulfonate, separate after layering, and evaporate the alcoholic water layer to obtain the product.

The comprehensive additive is: a compound of clay stabilizer, drainage aid and iron ion stabilizer, specifically composed of 20% clay stabilizer, 30% drainage aid, 20% iron ion stabilizer, and the rest is clear water.

The clay stabilizer is: small cationic quaternary ammonium salt, product code COP-1, molecular weight 500-600, manufactured by Xi'an Changqing Chemical Group Co., Ltd.

Said drainage aid: fluorocarbon surfactant, product code CF-5D, manufactured by Xi'an Changqing Chemical Group Co., Ltd.

The iron ion stabilizer is: mercaptoacetic acid.

Invention features:

The present invention is a pressure-reducing and increasing-injection method suitable for low-permeability tight reservoirs. Specifically, five steps are adopted to inject four different liquid slugs, and the comprehensive effect formed by the different functions of the four slugs reduces the conventional increasing-injection method. The water injection pressure of water injection wells where the measures are difficult to work is characterized in that: the first step is to replace the cleaning fluid, the liquid volume is 1-2 cubic meters, the well is closed for 50 minutes, the wellbore, oil pipe and hole impurities are cleaned, and the residual acid is replaced by the wellbore; the second Injection into the first front acid slug in the first step, the fluid volume is 1 times the wellbore volume; in the third step, the acid slug is injected into the second main body, and the fluid volume is 2 times the wellbore volume; Set the acid slug, the liquid volume is 2 times the wellbore volume; the fifth step is to squeeze and inject the fourth ultra-low interfacial tension surfactant slug, the liquid volume is 5-6 times the wellbore volume, and the surfactant concentration is 0.05%-0.15 %.

The present invention carries out innovations in three aspects in the fracturing fluid technology.

1. New method of note

One cleaning solution plus three acid slugs with different concentrations, and the last surfactant slug injection method.

2. Three new slug recipes

Pre-acid: 11%-13% hydrochloric acid, 2%-4% glacial acetic acid, 2%-4% comprehensive additives, 2%-4% ammonium chloride.

Main acid: 11%-13% hydrochloric acid, 4%-6% glacial acetic acid, 1%-3% hydrofluoric acid, 2%-4% comprehensive additives, 2%-4% ammonium chloride.

Post acid: 11%-13% hydrochloric acid, 2%-4% glacial acetic acid, 2%-4% comprehensive additives, 2%-4% ammonium chloride.

3. New surfactants

A new type of anionic surfactant has been developed, which has ultra-low interfacial tension. The interfacial tension between an aqueous solution with a mass fraction of 0.15% and aviation kerosene is 0.021mN/m. The specific performance indicators are shown in Attached Table 1. The preparation method of the ultra-low interfacial tension surfactant: select the low-condensation naphthenic decompression distillate oil in Xinjiang as raw material, sulfonate with gaseous sulfur trioxide; Put 500-650 grams of distillate oil into the reaction bottle, stir and heat up to 60°C, and weigh the required amount of liquid sulfur trioxide in another 500 ml three-necked bottle equipped with a thermometer. The mass ratio of oil and sulfur trioxide is 1:1.4, water bath heat preservation to control the production of sulfur trioxide gas; the air in the air cylinder is dried and measured by a gas flow meter, and then enters the sulfur trioxide bottle, and the sulfur trioxide is gradually blown out, and the blown gas is heated by the buffer bottle After heating up to 60-70°C, import it into the sulfonation reaction bottle until all the sulfur trioxide has reacted; continue to react at 60°C for half an hour, stop stirring; keep warm and settle for half an hour, release unreacted oil and petroleum sulfonic acid, and keep stirring at 60°C Neutralize to pH 7-7.5 with 20% sodium hydroxide aqueous solution by mass, add 300 ml of 50% ethanol/water solution by mass for extraction, obtain petroleum sulfonate, separate after layering, and evaporate the alcoholic water layer to obtain the product.

Description of drawings

Fig. 1 Well example 1 of five-step four-slug method for increasing injection

Fig. 2 Well example 2 of five-step four-slug method for increasing injection

Detailed ways:

Example 1:

Well No. 1 was pumped on August 7, 2006. The initial daily injection was 20m ³ , the actual daily injection was 22m ³ , the oil pressure was 16.3MPa, and the casing pressure was 16.0MPa. With the extension of the water injection time, injection began in November 2009. However, conventional soil acid boost injection and polyhydric acid boost injection have been carried out successively, and the water injection pressure has not dropped significantly. Currently, the oil pressure is 16.5MPa, the casing pressure is 16.5MPa, and the daily water injection volume is only 5m ³ . In March 2010, the five-step four-slug method was implemented: the first step is to replace the cleaning solution, the formula is: 7% hydrochloric acid, 2% glacial acetic acid, 2% comprehensive additives, 2% ammonium chloride, the liquid volume is 1 square, Shut in the well for 50 minutes, and the residual acid is replaced in the wellbore; the second step is to inject the first pre-acid slug, the pre-acid formula is: 11% hydrochloric acid, 2% glacial acetic acid, 2% comprehensive additives, 2% ammonium chloride, liquid The amount is 1 times the wellbore volume; the third step is to squeeze and inject the second main acid slug, the main acid: 11% hydrochloric acid, 4% glacial acetic acid, 1% hydrofluoric acid, 2% comprehensive additives, 2% ammonium chloride, liquid The volume is 2 times the wellbore volume; the fourth step is to squeeze and inject the third post-acid slug, post-acid: 13% hydrochloric acid, 4% glacial acetic acid, 4% comprehensive additives, 4% ammonium chloride, the liquid volume is 2 times Wellbore volume; the fifth step is positively squeezed into the fourth ultra-low interfacial tension surfactant slug, the liquid volume is 5 times the wellbore volume, and the surfactant concentration is 0.5%. After the injection increase, the water injection pressure drops to 9.5MPa for oil pressure, 9.5MPa for casing pressure, and the daily water injection volume is 20m ³ , which meets the injection requirements and is effective so far, as shown in Figure 1.

Example 2:

Well No. 2 was pumped on August 10, 2006. The initial daily injection was 20m ³ , the actual daily injection was 20m ³ , the oil pressure was 13.5MPa, and the casing pressure was 13.5MPa. With the extension of the water injection time, injection began in January 2010. If not, conventional soil acid injection and retarded acid injection were carried out successively, and the water injection pressure did not drop significantly. Currently, the oil pressure is 18.0MPa, and the casing pressure is 17.8MPa, and the injection cannot be made. In April 2010, the five-step four-slug method of the present invention was implemented: the first step is to replace the cleaning solution, the formula is: 8% hydrochloric acid, 4% glacial acetic acid, 4% comprehensive additives, 4% ammonium chloride, liquid volume 2 squares, shut down the well for 50 minutes, and replace the residual acid in the wellbore; the second step is to inject the first pre-acid slug, the pre-acid formula is: 13% hydrochloric acid, 4% glacial acetic acid, 4% comprehensive additives, 4% chlorination Ammonium, the liquid volume is 1 times the wellbore volume; the third step is positive extrusion injection into the second main acid slug, main acid: 13% hydrochloric acid, 6% glacial acetic acid, 3% hydrofluoric acid, 4% comprehensive additives, 4% chlorination Ammonium, the liquid volume is 2 times the wellbore volume; the fourth step is positive extrusion injection and the third post-acid slug, post-acid: 13% hydrochloric acid, 4% glacial acetic acid, 4% comprehensive additives, 4% ammonium chloride, liquid volume 2 times the volume of the wellbore; in the fifth step, positive extrusion injects the fourth ultra-low interfacial tension surfactant slug, the liquid volume is 5 times the volume of the wellbore, and the concentration of the surfactant is 0.15%. After the injection increase, the water injection pressure drops to 10.5MPa for oil pressure, 10.5MPa for casing pressure, and 25m ³ water injection per day, which meets the injection requirements and is effective so far, as shown in Figure 2.

Attached to the manual:

Table 1 Anionic surfactant performance evaluation

Claims (5)

1. method that reduces reservoir well water injection pressure is characterized in that:

The first step is just being replaced cleaning fluid, liquid measure 1-2 side, and closing well reaction 50min cleans pit shaft, oil pipe and eyelet impurity, and pit shaft is replaced out in residual acid;

Second step injects the first preposition sour slug, and liquid measure is 1 times of hole volume;

The 3rd step was just squeezing into the second main acid slug, and liquid measure is 2 times of hole volumes;

The 4th step was just squeezing into the 3rd rearmounted sour slug, and liquid measure is 2 times of hole volumes;

The 5th step was just squeezing into the 4th surfactant slug, and liquid measure is 5-6 times of hole volume, and the surfactant mass concentration is 0.15-0.05%, and all the other are clear water;

Described cleaning fluid is by mass%: 7-8% hydrochloric acid, and the 2-4% glacial acetic acid, the 2-4% composite additive, 2-4% ammonium chloride, all the other are clear water;

Described preposition acid is by mass%: 11-13% hydrochloric acid, and the 2-4% glacial acetic acid, the 2-4% composite additive, 2-4% ammonium chloride, all the other are clear water;

Described main acid is by mass%: 11-13% hydrochloric acid, and the 4-6% glacial acetic acid, 1-3% hydrofluoric acid, the 2-4% composite additive, 2-4% ammonium chloride, all the other are clear water;

Described rearmounted acid is by mass%: 11-13% hydrochloric acid, and the 2-4% glacial acetic acid, the 2-4% composite additive, 2-4% ammonium chloride, all the other are clear water;

Described surfactant preparation method: select the low solidifying cycloalkyl vacuum distillate in Xinjiang to be raw material, SO 3 sulfonated with gas; Take 1000 milliliters of there-necked flasks that agitator, thermometer are housed as the sulfonating reaction bottle, put into 500-650 gram fraction oil, agitating heating is warming up to 60 ℃, be weighed into required sulfan amount with 500 milliliters of there-necked flasks that thermometer is housed in addition, the mass ratio of oil and sulfur trioxide is 1: 1.4, and water bath heat preservation is with the generation of control sulfur trioxide gas; The air drying of air steel cylinder also enters in the sulfur trioxide bottle by after the gas flowmeter metering, and sulfur trioxide is blown out gradually, and the gas that blows out imports the sulfonating reaction bottle until the sulfur trioxide total overall reaction is complete after surge flask is heated to 60-70 ℃; Continue to react half an hour in 60C, stop to stir; Insulation sedimentation half an hour, emit unreacted oil and mahogany acid, be neutralized to pH7-7.5 with quality 20% sodium hydrate aqueous solution at 60 ℃ under constantly stirring, add 300 milliliters of quality 50% ethanol/water solution extractions, get petroleum sulfonate, separate after the placement layering, evaporate to dryness alcohol water layer namely gets product.

2. the method for reduction reservoir well water injection pressure according to claim 1, it is characterized in that: described composite additive is the compound of clay stabilizer, cleanup additive and ferrous stability, concrete 20% clay stabilizer, 30% cleanup additive, 20% ferrous stability of forming, all the other are clear water.

3. the method for reduction reservoir well water injection pressure according to claim 2, it is characterized in that: described clay stabilizer is: small cation quaternary ammonium salt, product designation COP-1, molecular weight 500-600, manufacturer Xi'an long celebrating Chemical Group Co., Ltd.

4. the method for reduction reservoir well water injection pressure according to claim 2 is characterized in that: described cleanup additive: fluorocarbon surfactant, product designation CF-5D, manufacturer Xi'an long celebrating Chemical Group Co., Ltd.

5. the method for reduction reservoir well water injection pressure according to claim 2, it is characterized in that: described ferrous stability is: TGA.

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