CN100395429C - Injection pretreatment method for oil water well - Google Patents

Abstract

The present invention relates to an oil-water well shifting injection pretreatment method which relates to the oil extraction technique of oil fields. The present invention has the following steps: a pump truck is used for successively squeezing the prepad fluid composed of an expansion-resistant expansion-reducing agent, a visbreaking thickness-reducing agent and a water-soluble demulsifying agent, aqueous solution-working solution composed of hydrochloric acid, fluohydric acid, corrosion inhibitor-mud acid, iron ion stabilizing agent-NTA, cleanup additive, an expansion-resisting expansion-reducing agent, ethylene glycol butyl ether, and a visbreaking thickness-reducing agent and clear water overflush fluid into the stratum, and a well is closed to react for 4-6 h; backflow is carried out, pH test paper is used for detecting pH, when the pH is equal to 7, the backflow is ended, and the well is opened to carry out normal production. The oil-water well shifting injection pretreatment method of the present invention can effectively relieve the blocking of the oil field stratum, and can perform effects of depressurization and injection increasing. After a shifting injection water well is pre-treated, the injection pressure slowly rises, and the energy degradation can be well delayed. Compared with ten squeezing expansion-resistant water injection wells, 45 wells built at present has the advantage that the pressure drops to 2.4Mpa; the present invention is a technological process treating inner and outer problems.

Description

Injection pretreatment method for oil water well

Technical field:

The invention belongs to oil recovery technique field, oil field, especially relate to a kind of injection pretreatment method for oil water well that improves oil production.

Background technology:

In oilfield development process, because stratum energy weakens gradually, a large amount of crude oil is trapped on the stratum in and can't exploits, thereby make the recovery ratio decline of crude oil.Therefore, in order to recover stratum energy, make residual oil exploit out as much as possible, at present, the most frequently used method is to adopt waterflooding extraction.The following two kinds of forms of the basic at present employing of waterflooding extraction: 1) new well stake:, adopt the early flooding mode or carry out waterflooding extraction with the exploitation method of synchronization promptly at new probing block brill water injection well.2) oil well metaideophone: promptly owing to the growth of some block oil well along with the exploitation time, the stratum energy fall is very fast, and some oil well has not had extraction value, but because this block also exists not exploitation of remaining oil, promptly recovery percent of reserves is lower.Therefore transfer some pumpingh well of this block to water injection well, increase stratum energy by water filling, improve recovery percent of reserves with this.But in the waterflooding extraction process, there are two problems: the one, inject the water absorbing capacity that water has reduced well, changed the fluid behaviour of oil reservoir, the stratum, near wellbore zone has formed obstruction, causes that injection pressure rises year by year; The 2nd, the chemical compatibility that injects water and formation water is poor, and corrosion and scaling is serious, and the reservoir geology condition is poor in addition, permeability is low, and shale content is higher, and it is fast to cause injection pressure to rise, and causes the oil reservoir injury.Because the problem of above-mentioned two aspects makes water injection well pressure constantly soaring, the existing 42 mouthfuls of well saliva well injection pressures of the big feelings word of Jilin Oil Field well surpass 10Mpa at present, 24 mouthfuls of wherein black 79 blocks, and 4 mouthfuls of black 75 blocks, 10 mouthfuls of black 46 blocks, the highest injection pressure reaches 18.1Mpa.So high water injection pressure finally causes water injection well to be shorted, even annotates not advance, and stratum energy can not get replenishing, and oil well output descends on every side.

At present, at fast this problem of pressure rising behind water injection well stake and the metaideophone, each oil recovery factory mainly takes these main means of swollen processing are prevented in stake and metaideophone well.This method can play a role to new stake well, but this effect is temporary transient.This be since for new stake well because the clay mineral on stratum clay swell speed under the expansion-resisting agent effect reduces, but along with the effect of long waterflooding extraction expansion-resisting agent fades away, the water injection pressure of water injection well will soon rise.And for the increase of metaideophone well along with the exploitation time, clay mineral is under the effect of surface hydration power, infiltration aquation and capillary force, crystals of clay surface (the expansive clay surface comprises external surface and inner surface) adsorbed water molecule, first floor are that the oxygen atom of the hexagon grid of hydrone and surface of clay forms hydrogen bond and keeps from the teeth outwards.Hydrone also is combined into the hexagonal ring by hydrogen bond, and the second layer also is connected with hydrogen bond with first floor with analogue, and later water layer continues like this, and the intensity of hydrogen bond increases with the distance of leaving the surface and reduces.In addition, owing to the concentration of the cation concn between the crystal layer greater than solution inside, therefore, the diffusion of water generation concentration difference enters interlayer, increases lattice spacing thus, thereby forms diffuse double layer.The volume that osmotic swelling causes increases more much bigger than lattice dilatation, and volume can increase 20-50 doubly.Because metaideophone well clay mineral Long contact time water, clay mineral has expanded fully already.Therefore, behind the adding expansion-resisting agent clay has not been had effect, in addition, because long-time exploitation, the stratum of near wellbore zone has formed organic and the inorganic scale class already, and the dirty class of this kind is not removed, and only depends on expansion-resisting agent not have antihypertensive effect.

Summary of the invention:

Technical problem to be solved by this invention provides a kind of effective releasing oil field stratum and stops up, can play the injection pretreatment method for oil water well of step-down augmented injection effect, use this method to carry out for moving on to water injection well that injection pressure rises slowly after the preliminary treatment, can delay energy well and successively decrease, be a kind of technique processing method for the treatment of both principal and secondary aspect of disease.

Injection pretreatment method for oil water well of the present invention comprises the following steps:

A) preparation prepad fluid, the percentage by weight of prepad fluid consists of: anti-swollenly contract swollen dose: viscosity reduction is separated thick dose: water-soluble demulsifier=6-10: 3-15: 0.5-3, wherein, the anti-swollen percentage by weight that contracts swollen dose consists of: ammonium chloride 3-8%, small cation polymer DDHC 30-50%, dodecyl benzyl dimethyl ammonium chloride 1227 is 8-10%, surplus is a water, and viscosity reduction is separated thick dose percentage by weight and consisted of: benzene mixed 75-85%, emulsifier op-10 is 3-6%, emulsifier SP-80 is 4-5%, ethene and vinyl acetate co-polymer EVA are 2-3%, methyl alcohol is 5-10%, surplus is a water;

B) preparation working solution, the percentage by weight of working solution consists of: hydrochloric acid 8-15%, hydrofluoric acid 2-6%, corrosion inhibiter-mud acid 1.5-2%, ferrous stability NTA 0.5-3%, cleanup additive ZA-5 are 0.3-1%, prevent that swollen contract swollen dose of 0.5-1%, butyl glycol ether 0.3-1%, viscosity reduction are separated thick dose of 2-10%, surplus is;

C) after: clear water;

D) with pump truck prepad fluid, working solution, after are clamp-oned the stratum successively, closing well reaction 4-6 hour;

E) row of returning returns row and finishes when measuring PH=7 with the PH test paper, ordinary production drives a well.

Water-soluble demulsifier is LG938.

Injection pretreatment method for oil water well of the present invention is to set about from solving the soaring fast problem root of pressure, can effectively remove oil field stratum and stop up, and can play step-down augmented injection effect.Carry out for moving on to water injection well that injection pressure rises slowly after the preliminary treatment, can delay energy well and successively decrease.The 45 mouthfuls of wells of totally constructing at present, the pressure decline 2.4Mpa that compares with the water injection well of 10 mouthfuls of crowded expansion-resisting agents is a kind of process for the treatment of both principal and secondary aspect of disease.

Description of drawings:

Fig. 1 adds expansion-resisting agent effect correlation curve figure before preceding preliminary treatment of universe Bei60-19Jing stake and the universe Bei18-2Jing stake;

Fig. 2 is the preceding preliminary treatment of black 98 blocks stake and adds expansion-resisting agent effect correlation curve figure;

Fig. 3 adds expansion-resisting agent effect correlation curve figure before preceding preliminary treatment of black 98 blocks stake and the stake;

Fig. 4 adds expansion-resisting agent effect correlation curve figure before black preceding preliminary treatment of 123-4-4 well stake and the stake of black 123-5-5 well.

Further specify the present invention below by the test example.

Experimental example 1 dirty alanysis and the countermeasure of taking

1, dirty class is formed

We have chosen Qianan water injection well dirt sample, and after calcining and acid solution corrosion, it is composed as follows to record dirty class: table 1

The dirt class is formed	Organic deposition (%)	Inorganic scale (%)	Acid non-soluble substance (%)
				Dirt sample 1#	21.56％	76.30％	2.14％
Dirt sample 2#	42.60％	54.77％	2.63％

2, the countermeasure of taking

According to the dirty sample analysis result in area, Qianan as can be seen, in dirty sample, exist organic deposition, inorganic scale and acid non-soluble substance three class materials.At the composition of these dirty classes, reach the experience of acidifying measure over the years according to the scene, we have taked different laboratory tests.

(1) at the test of organic deposition class

Take by weighing the dirty sample of 1#, two mouthfuls of water injection wells of 2#, put into the beaker that variable concentrations changes preceding pretreating agent respectively, under 50 ℃, the cleaning efficiency in the record different time.Experimental data sees the following form 2.Data are separated in the thick agent solution at the viscosity reduction of 2%-11% variable concentrations for the organic deposition class as can be seen from table, under the temperature of setting, clean basically in the 3h and finish.

(the cleaning rate of dirty sample of 1#/2#) under the variable concentrations different time

Table 2

(2) at the test of inorganic scale class

Get the dirty sample of 1#, two mouthfuls of water injection wells of 2#, put into respectively the beaker that variable concentrations changes preceding pretreating agent is housed, under 50 ℃, the phenomenon after corrosion rate in the record different time and corrosion are finished, experimental data sees the following form 3.

(the cleaning rate of dirty sample of 1#/2#) under the variable concentrations different time

Table 3

(3) selection of auxiliary agent

For in order to be effective, by laboratory experiment prescription is screened, in pretreatment fluid, added cleanup additive, corrosion inhibiter, stabilizing agent.

1. the selection of cleanup additive

The cleanup additive of adding 1.0% in the treatment fluid proportioning can make reacted raffinate be easy to return and discharge the stratum, and can make rock keep water-wet, and contact angle descends, thereby greatly reduces the interfacial tension of rock and crude oil, improves oleic permeability.

2. anti-swollen swollen dose the selection of contracting

Because there are the sensitiveness mineral in the oil field, Qianan, because the exploitation clay mineral expands fully already for a long time, therefore for the clay mineral completely that expands, simple expansion-resisting agent is inoperative, and in view of this kind situation, we have developed and have prevented swollenly contracting swollen dose.The adding of this agent, the swollen while stabilizing agent that not only clay that expands completely can be contracted adsorbs at particle surface, makes its particle be difficult for being combined into bulky grain and stops up the duct.The mechanism and the characteristics of this agent are as follows:

2.1

The anti-swollen swollen dose of mechanism of action that contracts

2.1.1

Compression double electric layer mechanism

Enter between the clay particle crystal layer through designing synthetic molecule, it has sufficient positive charge ion and relies in its electrostatic attraction absorption and negative electrical charge, and superfluous positive charge makes sex reversal in the clay particle, compression double electric layer, and crystal layer shrinks, and has reduced the argillic horizon spacing.

For the clay that has expanded, use suitable molecule to change the charged character of clay effectively, be to make clay produce the dominant mechanism of shrinking.And unexpanded clay, generally electronegative at its forming process medium clay soil crystal, according to " elrectroneutrality pcharge-neutrality principle ", promptly have the counter ion of equivalent to be adsorbed on surface of clay, the positive electricity group in the clay treatment agent molecule just can with the lip-deep low price cation of clay crystal layer generation cation exch ange adsorption.

2.1.2

Clay mechanism transition

Composition in the clay treating chemicals can make the transition the expansive clay mineral, makes it dehydration.Can weaken or eliminate the cation exchange capacity (CEC) of clay mineral, make the expansive clay mineral show non-expansibility.

2.1.3

" bag quilt " mechanism

Should prevent swollen swollen agent molecule and the strong electrostatic attraction of clay particle of contracting, and macromolecule was adsorbed on clay or other particulate securely form layer protective layer, thereby stoped the hydration of clay effectively.

2.1.4

The multiple spot adsorption mechanism

Make full use of on the chain length of the appropriateness that has of the anti-swollen swollen dose of branch that contract and the chain and have specific functional group, be adsorbed onto simultaneously on a plurality of crystal layers and the particulate, thereby suppressed Dispersion of Clay and migration effectively.This mechanism also can be referred to as " bridging " mechanism.

Should anti-swollen contracting swollen dose be the multi-functional clay mineral inorganic agent that comprehensive above four big mechanism designs are synthesized, it by with clay mineral generation physical-chemical reaction, make the clay lattice modification, do not expand after making its chance water; The clay lattice that has expanded, by discharging hydrone after the chemical reaction modification, lattice dwindles.And make the clay material and the former stratum mineral strong bonded of these modifications by the multiple spot suction-operated, thus avoided clay mineral water-swellable, migration to damage to the stratum, improve the oil and gas development effect, and saved a large amount of stratum improvement expenseses.

2.2 main feature

2.2.1 anti-swollen, swollen the uniting two into one of contracting to the expansive clay mineral;

2.2.2 the particle diameter of clay suspension is diminished;

2.2.3 excellent compatibility is arranged with formation water, fresh water;

2.2.4 excellent compatibility is arranged with acidifying composition, pressure break composition and inorganic salts;

2.2.5 the prepad fluid as acidifying, pressure break has good synergistic effect.

3. ferrous stability is selected

During the acid treatment stratum, it is generally acknowledged when residual sour pH value reaches 2.2, begin to form gel Fe (OH) ₃Precipitation, precipitation is just complete when PH is 3.2, in order to prevent the generation of secondary precipitation, in treatment fluid, add ferrous stability, this stabilizing agent and main body acid solution compatibility, in acid medium and in the neutral medium, with the iron complexing advantages of higher stability is arranged all, still have stablizing effect preferably during greater than 90 ℃ in temperature.

4. the selection of corrosion inhibiter

Characteristics at Qianan oil field individual well production capacity, adopt the fixed tubular column construction technology, in order to guarantee that tubing string is not corroded in work progress, we have carried out preferably acidification corrosion inhibitor, by corrosion inhibition rate test and compatibility test, we have selected corrosion inhibiter-mud acid, corrosion inhibition rate reaches more than 98%, and also proves the use of this corrosion inhibiter in the field conduct process, guarantee the enforcement of fixed tubular column acidification to dispel block construction technology, reached economic validity.

Experimental example 2

Choose the preceding 6 mouthfuls of wells of preliminary treatment of the stake with contrast property, squeeze 12 mouthfuls of wells of expansion-resisting agent.Statistics shows: adopt the initial stage injection pressure of the crowded expansion-resisting agent well of well initial stage injection pressure of the preceding preconditioning technique of stake to reduce 3.5MPa.

Project	Statistics well number	Initial stage pressure	Average water injection time	Present oil pressure	Present water injection rate
						Preliminary treatment	6	0.9	278 days	6.7	50.0
Squeeze expansion-resisting agent	11	5.8	343 days	10.2	45.9

Experimental example 3

Alternative is got the preceding 4 mouthfuls of wells of preliminary treatment of the stake with contrast property, squeezes 8 mouthfuls of wells of expansion-resisting agent.Statistics shows: the injection pressure that adopts the well initial stage injection pressure of preconditioning technique before the stake to squeeze the expansion-resisting agent well reduces 5.3MPa, water filling after 120 days pressure still reduce 3.9MPa.

Project	Statistics well number	Initial stage pressure	Average water injection time	Oil pressure
					Preliminary treatment	4	0.9	120 days	5.8
Squeeze expansion-resisting agent	8	6.2	120 days	9.7

Experimental example 4

The northern 60-19 of two mouthfuls of well universes and two mouthfuls of wells of universe north 18-2 that development layer position, universe north is identical compare.These two mouthfuls of well injection intervals are blue or green three VI, VII sand group, squeeze expansion-resisting agent during the stake on January 27th, 2005 of universe north 18-2 well, adopt preconditioning technique during the stake on April 28th, 2005 of universe north 60-19 well.

15 days injection pressures of universe north 18-2 well water filling are 5.2MPa, and 15 days injection pressures of universe north 60-19 well water filling are 0.2MPa, the initial stage injection pressure obviously reduces 5MPa, water filling after 270 days universe north 60-19 well injection pressure only be 5.4MPa, and universe north 60-19 well injection pressure is 7.5MPa, reduces 2.1MPa by contrast.Fig. 1 is seen in its effect contrast.

Experimental example 5

Black 98-6-2 and black 98-7-1, black 98-15-9, black 98-7-5 four-hole well, this four-hole well injection interval is blue or green three XI, XII sand group, adopts preconditioning technique during the stake on April 28th, 2005 of black 98-6-2 well, squeeze note expansion-resisting agent before other three mouthfuls of well stakes.

Black 15 days injection pressures of 98-6-2 well water filling are 0.9MPa, average injection pressure 6.5MPa reduces 5.6MPa than other three mouthfuls of wells, it is 6.1MPa that water filling was deceived 98-6-2 well injection pressure after 195 days, and other three mouthfuls of average injection pressures of well are 10.9MPa, reduce 4.8MPa by contrast.Fig. 2 is seen in its effect contrast.

Experimental example 6

Black 98-5-4, black 98-2-4 and black 98-11-17, black 98-11-5, black 98-11-9, black 98-13-6, black 98-15-13, black eight mouthfuls of wells of 98-7-9, injection interval is blue or green three X, XI, XII sand group, adopt preconditioning technique during two mouthfuls of well stakes of black 98-5-4, black 98-2-4, squeeze note expansion-resisting agent before other six mouthfuls of well stakes.

Six mouthfuls of well water fillings of squeeze note expansion-resisting agent 15 days, average injection pressure 5.4MPa, two mouthfuls of well water fillings of employing preconditioning technique 15 days, injection pressure average out to 1.2MPa, compare and reduce 3.9MPa, water filling is after 270 days, and six mouthfuls of average injection pressures of well of squeeze note expansion-resisting agent are 10.4MPa, adopting two mouthfuls of average injection pressures of well of preconditioning technique is 6.9MPa, reduces 3.5MPa by contrast.Fig. 3 is seen in its effect contrast.

Experimental example 7

Black 123-5-5 and two mouthfuls of well injection intervals of black 123-4-4 are blue or green two IV, V sand group, and a blue or green III sand group is squeezed expansion-resisting agent during the stake on March 31st, 2005 of black 123-5-5 well, adopt preconditioning technique during the stake on August 21st, 2005 of black 123-4-4 well.

Black 15 days injection pressures of 123-5-5 water filling are 6.5MPa, and black 15 days injection pressures of 123-4-4 well water filling are 0MPa, the initial stage injection pressure obviously reduces 6.5MPa, it is 10.2MPa that water filling was deceived 123-5-5 well injection pressure after 150 days, and black 123-4-4 well injection pressure only is 8.2MPa, reduces 2.0MPa by contrast.Fig. 4 is seen in its effect contrast

Conclusion: by above contrast, we can draw the present invention and have following effect:

1. can obviously reduce the initial stage injection pressure;

2. can effectively slow down the too fast problem of pressure rising;

3. injection pressure held stationary in a very long time can reduce to a certain extent owing to the high expense of taking the step-down augmented injection of injection pressure.

Embodiment 1 injection pretreatment method for oil water well comprises the steps:

A) preparation prepad fluid, the percentage by weight of prepad fluid consists of: anti-swollenly contract swollen dose: viscosity reduction is separated thick dose: water-soluble demulsifier=6: 3: 0.5, wherein, the anti-swollen percentage by weight that contracts swollen dose consists of: ammonium chloride 3%, small cation polymer DDHC 30%, dodecyl benzyl dimethyl ammonium chloride 1227 is 8%, surplus is a water, viscosity reduction is separated thick dose percentage by weight and is consisted of: benzene mixed 75%, emulsifier op-10 is 3%, emulsifier SP-80 is 4%, ethene and vinyl acetate co-polymer EVA are 2%, methyl alcohol is 5%, surplus is a water, and water-soluble demulsifier is LG938;

B) preparation working solution, the percentage by weight of working solution consists of: hydrochloric acid 8%, hydrofluoric acid 2%, corrosion inhibiter mud acid 1.5%, ferrous stability NTA 0.5%, cleanup additive ZA-5 be 0.3%, anti-swollen contract swollen dose 0.5%, butyl glycol ether 0.3%, viscosity reduction are separated thick dose 2%, surplus and be;

C) after: clear water;

D) with pump truck prepad fluid, working solution, after are clamp-oned the stratum successively, closing well reaction 4-6 hour;

E) row of returning returns row and finishes when measuring PH=7 with the PH test paper, ordinary production drives a well.

Embodiment 2 injection pretreatment method for oil water well comprise the steps:

A) preparation prepad fluid, the percentage by weight of prepad fluid consists of: anti-swollenly contract swollen dose: viscosity reduction is separated thick dose: water-soluble demulsifier=10: 15: 3, wherein, the anti-swollen percentage by weight that contracts swollen dose consists of: ammonium chloride 8%, small cation polymer DDHC 50%, dodecyl benzyl dimethyl ammonium chloride 1227 is 10%, surplus is a water, viscosity reduction is separated thick dose percentage by weight and consisted of: benzene mixed is 85%, emulsifier op-10 is 6%, emulsifier SP-80 is 5%, ethene and vinyl acetate co-polymer EVA are 3%, methyl alcohol is 10%, surplus is a water, and water-soluble demulsifier is LG938;

B) preparation working solution, the percentage by weight of working solution consists of: hydrochloric acid 15%, hydrofluoric acid 6%, corrosion inhibiter mud acid 2%, ferrous stability NTA 3%, cleanup additive ZA-5 be 1%, anti-swollen contract swollen dose 1%, butyl glycol ether 1%, viscosity reduction are separated thick dose 10%, surplus and be;

C) after: clear water;

D) with pump truck prepad fluid, working solution, after are clamp-oned the stratum successively, closing well reaction 4-6 hour;

E) row of returning returns row and finishes when measuring PH=7 with the PH test paper, ordinary production drives a well.Embodiment 3 injection pretreatment method for oil water well comprise the steps:

A) preparation prepad fluid, the percentage by weight of prepad fluid consists of: anti-swollenly contract swollen dose: viscosity reduction is separated thick dose: water-soluble demulsifier=8: 10: 2, wherein, the anti-swollen percentage by weight that contracts swollen dose consists of: ammonium chloride 5%, small cation polymer DDHC 40%, dodecyl benzyl dimethyl ammonium chloride 1227 is 9%, surplus is a water, viscosity reduction is separated thick dose percentage by weight and consisted of: benzene mixed is 80%, emulsifier op-10 is 5%, emulsifier SP-80 is 5%, ethene and vinyl acetate co-polymer EVA are 2.5%, methyl alcohol is 8%, surplus is a water, and water-soluble demulsifier is LG938;

B) preparation working solution, the percentage by weight of working solution consists of: hydrochloric acid 12%, hydrofluoric acid 4%, corrosion inhibiter mud acid 2%, ferrous stability NTA 2%, cleanup additive ZA-5 be 0.5%, anti-swollen contract swollen dose 0.8%, butyl glycol ether 0.5%, viscosity reduction are separated thick dose 5%, surplus and be;

C) after: clear water;

D) with pump truck prepad fluid, working solution, after are clamp-oned the stratum successively, closing well reaction 4-6 hour;

E) row of returning returns row and finishes when measuring PH=7 with the PH test paper, ordinary production drives a well.

Claims (2)

1. an injection pretreatment method for oil water well is characterized in that: comprise the following steps:

A) preparation prepad fluid, the percentage by weight of prepad fluid consists of: anti-swollenly contract swollen dose: viscosity reduction is separated thick dose: water-soluble demulsifier=6-10: 3-15: 0.5-3, wherein, the anti-swollen percentage by weight that contracts swollen dose consists of: ammonium chloride 3-8%, small cation polymer DDHC 30-50%, dodecyl benzyl dimethyl ammonium chloride 1227 is 8-10%, surplus is a water, and viscosity reduction is separated thick dose percentage by weight and consisted of: benzene mixed is 75-85%, emulsifier op-10 is 3-6%, emulsifier SP-80 is 4-5%, ethene and vinyl acetate co-polymer EVA are 2-3%, methyl alcohol is 5-10%, surplus is a water;

B) preparation working solution, the percentage by weight of working solution consists of: hydrochloric acid 8-15%, hydrofluoric acid 2-6%, corrosion inhibiter mud acid 1.5-2%, ferrous stability NTA 0.5-3%, cleanup additive ZA-5 are 0.3-1%, prevent that swollen contract swollen dose of 0.5-1%, butyl glycol ether 0.3-1%, viscosity reduction are separated thick dose of 2-10%, surplus is;

C) after: clear water;

D) with pump truck prepad fluid, working solution, after are clamp-oned the stratum successively, closing well reaction 4-6 hour;

E) row of returning returns row and finishes when measuring PH=7 with the PH test paper, ordinary production drives a well.

2. injection pretreatment method for oil water well according to claim 1 is characterized in that: water-soluble demulsifier is LG938.

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