CN111322052A - Method for injecting oil displacement agent and plugging agent into thick oil layer by fracturing to drive and wash low-water-content part and plug strong-water-washing strip - Google Patents

Abstract

The invention relates to a method for injecting an oil displacement agent and a plugging agent into a thick oil layer by fracturing to drive and wash a low-water-content part and plug a strong washing strip. The problems that the conventional development and excavation method cannot effectively block the strong water washing strip in the thick oil layer, the inefficient ineffective circulation is caused, and the residual oil in the low water-containing part cannot be effectively used are mainly solved. The method is characterized in that: the method comprises the following steps: (1) determining a construction target position; (2) determining the dosage of the plugging agent at the target layer; (3) determining the consumption of the oil displacement agent at the target layer; (4) determining well fracturing construction displacement; (5) determining a pump injection construction program; (6) and mixing and injecting the oil displacement agent and the plugging agent. The method utilizes fracturing to inject an oil displacement agent and a plugging agent into a thick oil layer to wash a low water-containing part and plug a strong water washing strip, and realizes effective excavation of residual oil at middle and weak water washing and unwashed parts in the thick oil layer after subsequent injection-production displacement recovery.

Description

Method for injecting oil displacement agent and plugging agent into thick oil layer by fracturing to drive and wash low-water-content part and plug strong-water-washing strip

The technical field is as follows:

the invention relates to the technical field of oil exploitation, in particular to a method for injecting an oil displacement agent and a plugging agent into a thick oil layer by fracturing to flush a low water-containing part and plug a strong water washing strip.

Background art:

after tertiary oil recovery development, the first-class oil layer and the second-class oil layer of the Daqing oil field are gradually transferred to subsequent water drive, a plurality of high-permeability strong water washing strips far exceeding the original oil layer condition are formed in the oil layer after years of injection, production and washing, and the strong water washing strips are expressed as low-efficiency and ineffective circulation in the subsequent water drive development process, so that residual oil at the top of a thick positive rhythm oil layer or at the middle-upper low water washing part of a composite rhythm oil layer cannot be effectively displaced and cannot be effectively used.

The development and excavation methods commonly used for oil fields at present comprise oil layer plugging, intermittent water injection adjustment and the like. The common oil layer plugging process of the oil field at present comprises chemical plugging and mechanical plugging: the chemical plugging is realized by injecting a plugging agent into pores of an oil layer through a conventional surface pump, and is influenced by the pressure bearing performance of the surface pump and the dilution of formation water, so that the plugging radius is small, the plugging strength is low, and the effect is not ideal. Mechanical plugging is to plug a blast hole by applying a mechanical tool in a shaft, and the vertical flow channeling still exists in an oil layer during the subsequent water injection development of a low water-containing part, so that the problem of ineffective circulation of a strong water washing strip cannot be solved. Intermittent water injection is realized by changing a water injection system, the ineffective circulating water injection amount can be controlled to a certain degree, but the problem of displacement of residual oil at a low water-cut part cannot be solved. At present, a process technology which can effectively control the low-efficiency ineffective circulation of a strong water washing strip in a thick oil layer and can drive and wash residual oil at a low water-containing part does not exist.

The invention content is as follows:

the invention aims to solve the problems that the conventional development and excavation method in the background technology can not effectively control the inefficient ineffective circulation of the strong water washing strip in the thick oil layer and the residual oil at the low water-containing part can not be effectively used, and provides a method for injecting an oil displacement agent and a plugging agent into the thick oil layer by means of fracturing to drive and wash the low water-containing part and plug the strong water washing strip. The method for injecting the oil displacement agent and the plugging agent into the thick oil layer to drive and wash the low water-containing part and plug the strong water washing strip by utilizing fracturing can realize that the oil displacement agent is pre-arranged in an oil inlet layer in a front hole cleaning mode in a certain longitudinal range of the wall surface of a fracturing fracture, the subsequent plugging agent is injected immediately, effective plugging of the thick oil layer strong water washing strip with certain thickness is realized, injection and production are recovered after plugging is successful, the oil displacement agent which is pre-arranged in the oil inlet layer forms flow-around extraction along the low water-containing part under the action of injection and production pressure, and the effect of driving and washing residual oil in the low water-containing part is.

The invention can solve the problems by the following technical scheme: the method for injecting the oil displacement agent and the plugging agent into a thick oil layer by fracturing to drive and wash a low water-containing part and plug a strong water washing strip comprises the following steps:

(1) the target well is preferably selected from the following steps: comprehensively optimizing a target well according to the position of an isolated well point, the combination of well cementation quality, perforation interpretation data, a reservoir stratum fine description result, a fine residual oil research result, reservoir stratum exploitation condition evaluation data and the like;

(2) determining the potential digging time of a target well: determining the excavation and submergence time according to the development dynamic trend, the decreasing rule and the current production condition of the target well, and selecting the time when the liquid amount decreases rapidly and the liquid supply is nearly insufficient to perform excavation and submergence;

(3) interval-making for the well of interest preferably: comprehensively optimizing the submerged layer section according to the single-layer jet-opening thickness, the hole seepage condition, the sand body development, the residual oil distribution condition, the single-layer historical utilization condition and the like;

(4) determining a diving scheme:

determining the fracturing half-seam length of the target interval according to the sand body distribution range, the isolated well point position and the residual oil enrichment range of the target interval;

II, calculating the amount of fracturing injection displacement fluid according to the half-seam length determined in the step I, the injection thickness, the porosity and the extraction degree of the target interval, and adjusting according to the heterogeneous condition of the sand body of the interval;

III, according to the half seam length determined in the step I, taking 3/4 of the half seam length as a supporting radius, and calculating the fracturing sand adding scale;

IV, determining a pump injection construction program: determining the number of injection slugs according to the amount of injected displacement fluid, determining a sand adding step according to the size of the sand adding scale, and replacing fracturing fluid to carry out sand adding support after the injection of the displacement fluid is finished;

(5) carrying out field implementation: the injected oil displacement agent consists of water and a surfactant, the injection displacement is determined according to the field small-scale test ground pressure condition after the oil displacement agent is mixed in proportion, the oil displacement fluid is injected according to the determined dosage by a determined pumping program, and the fracturing fluid is replaced after the injection is finished to carry out sand adding support according to the designed sand adding step.

The formula for calculating the oil displacement liquid consumption in the step (4) is as follows:

Q＝π×r²×H×Φ*β

wherein: r-fracture half-seam length m;

q-amount of flooding fluid m³；

H-the target layer opening thickness m;

phi-oil layer porosity%;

β -volume ratio of target layer.

The single-layer fracturing sand adding scale calculation formula of the step (4) is as follows:

q＝π×(3r/4)²×h；

wherein: r-fracture half-seam length m;

q-single layer section fracturing sand adding scale m³；

h-fracture horizontal crack height m.

The method for injecting the oil displacement agent and the plugging agent into a thick oil layer to drive and wash low-water-content parts and plug strong washing strips by utilizing fracturing comprises the steps of utilizing artificial hydraulic fracturing to press out cracks with a certain length in the oil layer, injecting a large-volume oil displacement liquid into a stratum to supplement energy through reasonable injection discharge capacity, injection scale and pump injection program, enabling the displacement liquid to be replaced with original fluid of the stratum, and meanwhile, adding sand to support and form a seepage passage with high flow conductivity after the injection of the oil displacement liquid is finished, so that the purpose of improving the residual reserve extraction degree of an isolated well point is achieved.

Compared with the background technology, the invention has the following beneficial effects: according to the method for injecting the oil-displacing agent and the plugging agent into the thick oil layer by using fracturing to displace and wash the low-water-content part and plug the strong-water-washing strip, the used oil-displacing agent and plugging agent system can meet the performance requirement of hydraulic fracturing joint-making working fluid, and the problems that the conventional development excavation and submergence technology is incomplete in plugging, ineffective in adjustment and incapable of displacing residual oil in the low-water-content part are solved.

The method utilizes fracturing to inject an oil displacement agent and a plugging agent into a thick oil layer to wash a low water-containing part and plug a strong water washing strip, and realizes effective excavation of residual oil at middle and weak water washing and unwashed parts in the thick oil layer after subsequent injection-production displacement recovery.

After the process is implemented, the well opening wellhead liquid production amount is reduced by 16.3 tons and the water content is reduced by 0.6 percent after the coagulation and diffusion are carried out for 72 hours, the plugging effect is obvious, after the subsequent water injection displacement is carried out for 7 months, the daily liquid production amount is reduced by 45.7 percent and the water content is reduced by 3.5 percent, and the problem of excavation of residual potential of middle and weak water-washed and unwashed parts in a thick oil layer after the polymer flooding is solved.

Description of the drawings:

FIG. 1 is a dynamic diagram of the L9-PS2133 well production in example 1 of the present invention;

FIG. 2 is a production dynamic diagram of the well communicating well of L9-PS2133 in example 1 of the present invention;

FIG. 3 is an explanatory view of the L9-PS2133 well water flooded layer in example 1 of the present invention;

FIG. 4 is a graph of the results of the four-parameter combination well log data interpretation of the L9-PS2133 well production profile in example 1 of the present invention;

FIG. 5 is a graph showing the identification of the dominant pathway of the L9-PS2133 well in example 1 of the present invention;

FIG. 6 is an explanatory evaluation chart of well cementation quality in example 1 of the present invention;

FIG. 7 is a transverse view of the development of a L9-PS2133 well lamina in example 1 of the present invention;

FIG. 8 is a phase diagram of a wellSIII 6+7 cell of L9-PS2133 in example 1 of the present invention;

FIG. 9 is a graph showing oil saturation levels of SIII4+5,SIII 6+7,SIII 8 and SIII9+10 units in example 1 of the present invention;

FIG. 10 is a chart of L9-PS2133 well plugging agent dosage optimization in example 1 of the present invention;

FIG. 11 is a chart of L9-PS2133 well sealer dosage optimization in example 1 of the present invention;

FIG. 12 is a chart showing the relationship between different displacement amounts and different liquid friction resistances inembodiment 1 of the present invention;

FIG. 13 is a time-varying graph of construction displacement and cumulative injection quantity in example 1 of the present invention;

FIG. 14 is an explanatory graph of L10-P181 downhole pressure testing in example 1 of the present invention;

FIG. 15 is a graphical representation of a fracturing job for a Bragg 9-PS2133 well in example 1 of the present invention;

FIG. 16 is a dynamic diagram of fracturing construction of a Horn 9-PS2133 well in example 1 of the present invention;

FIG. 17 is a schematic view of the process principle of the Bragg 9-PS2133 well in the example 1 of the present invention.

The specific implementation mode is as follows:

the invention will be further explained with reference to the following figures and examples:

example 1

The invention is further described in connection with the Daqing Changyuan class of thick oil layer L9-PS2133 well.

The technical principle of the well is shown in fig. 17, the evaluated dominant channel at the bottom of the thick oil layer is plugged from the end of the extraction well by using a plugging agent, and the injection well is normally injected after plugging, so that residual oil flows around from the top of the thick oil layer and is displaced into the extraction well.

L9-PS2133, putting into production in 2008 and 9 months, producing liquid 52t daily in the initial period of putting into production, producing oil 1t daily and containing 98.8% of water. 13000t of the current accumulated oil production, 53.3 percent of stage production degree, 92t of current daily oil production, 2.2t of daily oil production and 97.6 percent of water. The L9-PS2133 well production dynamics are shown in FIG. 1.

The well is provided with 4 ports which are communicated with an injection well, namely L9-PS2132, L9-PS2134, L9-PS2124 and L9-PS2202 respectively, the injection condition is stable, and the average daily injection is 305m³And 2 months for controlling ineffective injection, the daily injection amount is adjusted down to 235m³. The L9-PS2133 well communicating well production kinetic diagram is shown in FIG. 2.

Determining a construction target layer position

1. Interpretation of water flooded layer

The thin reservoir dissection of the thick oil layer Sa 3-7 is a first-class oil layer with good connectivity, after theSulIII 3 unit subdivides the structural units, the upper sand body is changed from first-class communication to second-class communication in the injection and production direction of the 9-PS2134 well, the high-water-content part is mainly concentrated at the bottom of the layer section, and the water flooded layer of the LPS2133 well is explained as shown in figure 3.

2. Well group water absorption profile data

The water absorption profile data of the L9-PS2133 well group before and after 2015 are shown in Table 1, when the block is in the polymer injection oil extraction stage, the statistical condition of the water absorption profile of the polymer injection well at the 4 ports of the well group shows that the water absorption proportion of the lower part of the SIII3-7 oil layer is 55.5%, and is 41.5% higher and 25.0% higher than that of the upper part and the middle part respectively, and the water absorption part is the main water absorption part. And when the block enters a subsequent water flooding stage in 2017, the invalid circulation of the oil layer III3-7 is serious, and water injection is controlled on the oil layer III3-7 of the well group in order to achieve the purpose of stabilizing oil and controlling water.

TABLE 1

3. Fluid production profile test data

And 6, carrying out a liquid production profile test in an L9-PS2133 well by six oil extraction plants in 4 and 11 days in 2018, and explaining a result diagram by four-parameter combination logging data of the production profile. FIG. 4 is a graph showing the results of the interpretation of the L9-PS2133 well production profile four-parameter combination log data.

L9-PS2133 well SIII3-7^{Lower part}The interval depth is 1021.6-1028 m, see the boxed well section of the figure, and the liquid production data shows SIII3-7^{Lower part}Interval liquid production capacity 17.4m³The/d, which accounts for only 22.2% of the total well fluid volume, is not the major fluid production zone, indicating that SIII3-7 was in the last two years^{Lower part}The oil layer has obvious effect of controlling water injection. Currently SIII3-7^{On the upper part}And SIII9+10 fluid production rose to 54.3% and 23.5% of the total well fluid volume, respectively, considering SIII3-7^{On the upper part}Oil layer was transformed by fracturing in 2013 and affected by waterflooding, SIII3-7^{On the upper part}The oil layer forms partial dominant permeability, and the four-parameter combination logging data interpretation data of the well production profile of the finished L9-PS2133 well are shown in the table 2.

TABLE 2

The identification of the dominant channel position of a thick oil layer, the explanation of well cementation quality test and the analysis result of a physical property interlayer are comprehensively analyzed, and the two dominant seepage channels exist in the current well. The L9-PS2133 well dominant channel identification is shown in FIG. 5.

4. Interpretation and evaluation of pre-cementing quality

In order to evaluate the well cementation quality of a high-water-flooded part finely and realize effective control of the process, sector cement bond logging is carried out on the well before pressing. According to analysis of the latest interpretation result, the depth of a perforated well section of an SIII3-7 oil layer is 1014.8-1028.0 m, the well cementation quality of upper and lower interval sections is good, the cementing index is greater than 0.8 at 1019-1021 m in the perforated well section, the consolidation quality is good, and the two sections with the well depth of 1010-1019 m and 1021-1028 m respectively correspond to the SIII3-7 oil layer and the cement cementing index is larger than 0.8^{On the upper part}And SIII3-7^{Lower part}The cementing index of the well cementation in the interval is less than 0.4, the consolidation quality is poor, and the position with good cementing quality is selected as much as possible by the fracture layer selection shadowAnd the channeling of the fracturing fluid outside the casing is avoided. The well cementation quality explanation and evaluation chart is shown in figure 6.

5. Fracture plugging horizon determination

Consider that SIII3-7 is currently available^{Lower part}The stratum reduces the liquid production strength of the stratum through well group water injection regulation, the construction time of 2 layers of one-time fracturing plugging is long, plugging agents seep into pipe columns and tool gaps to form gel, the risk of pipe column blocking exists, and research confirms that the fracturing plugging SIII3-7 of the time is carried out^{On the upper part}The layer is advantageous to be a seepage channel, the layer depth is 1014.8-1018.0 m, and the plugging thickness is 3.2 m. An transverse view of the development of the L9-PS2133 well lamina is shown in FIG. 7.

6. Potential identification

L9-PS2133 well development SIII3-10 horizon, total 3 sedimentation units, wherein the SIII3-7 layer is a river sand body which develops in a connected mode and belongs to a first oil layer, and SIII9+10 is a second oil layer, and as can be seen from the recognition of the dominant seepage channel and the chart of the Sal pattern sedimentation sand body in the figures 7-8, residual oil exists in the middle-low water-containing part at the upper part of the thick oil layer. The phase diagram of the L9-PS2133 well SIII 6+7 cell is shown in FIG. 8.

From the numerical and analog results of FIG. 9, the oil saturation of the unit SIII4+5 of the L9-PS2133 well is higher, about 40%, and the residual oil is richer than that of other units, and the comprehensive analysis shows that a certain amount of residual oil exists in the thick oil layer of the well SIII 3-7. The oil saturation map of the SIII4+5,SIII 6+7,SIII 8 and SIII9+10 units is shown in FIG. 9.

L9-PS2133 well carbon to oxygen ratio test results Table 3. The carbon-oxygen ratio test result before pressing shows that: the oil saturation degree is relatively high at the depth of 1018.0-1020.0mm, the oil saturation degree is shown as medium water flooding, and the residual oil is relatively enriched.

TABLE 3

Secondly, determining the dosage of the target layer plugging agent

The plugging agent is divided into a part for plugging stratum and a part for plugging aseam 2, and the dosage is respectively calculated by the following formula according to the plugging radius

By the formula Q ═ pi × r²×H×Φ

(1) Optimization of dosage of medicament for plugging stratum

An L9-PS2133 well plugging agent dosage optimization chart is obtained through calculation, and is shown in the attached figure 10.

The well has oil-water well spacing of 150m and reservoir porosity of 30%, and is optimized according to 35% fracture penetration ratio, the plugging thickness is calculated according to 3.2m, the plugging strength is considered, and the dosage of the plugging agent is finally optimized to be 8300m³。

(2) Dosage optimization of medicament for sealing seams

Calculating to obtain optimized plate for sealing agent dosage according to the above formula, as shown in FIG. 11, calculating according to the sealing thickness of 3.2m, considering the sealing strength, designing the sealing radius of 10m, and optimizing the sealing agent dosage of 300m³。

According to the characteristic that the requirement of the plugging strength of the deep part of the stratum is from low to high, by combining the gelling performance evaluation result of the polymer crosslinked gel prepared on site, two plugging agent slugs of the injected gel plugging agent and the sealing agent are designed, and the dosage optimization design results of the slugs of the L9-PS2133 well plugging agent slug and the dosage design table are shown in the table 4:

TABLE 4

Thirdly, determining the consumption of the oil displacement agent at the target layer position

The formula for calculating the dosage of the oil-displacing agent is that q is pi × (L/2)²×H×Φ-Q；

Calculate q 16986-³

Fourthly, determining the well fracturing construction discharge capacity:

performing on-site small fracturing test according to the physical property condition of the reservoir, and determining the construction displacement;

(1) blocking agent construction discharge capacity optimization

FIG. 12 is a chart of the relationship between the construction displacement and the friction resistance of different types of fracturing fluids.

And obtaining by combining a horizontal fracture reservoir filtration rate calculation formula: the construction discharge capacity is 3.5-5.0 m³At/min, the formation fluid loss is large and the fracture can be effectively extended.

In the formula:

pressure conductivity coefficient;

and (4) dimensionless quantity.

On-site step-lift displacement fracturing test results need to be combined, construction pressure is considered, and injection displacement of the medicament is optimized.

Meanwhile, in the stratum extension process of the fracture, along with the increase of the fracture radius r, the contact area of the fracture and the oil reservoir is increased, the filtration rate is increased, the injection displacement is optimized to be increased in a stepped mode, and a chart of the construction displacement and the accumulated injection displacement along with time is shown in fig. 13.

(2) Sealant discharge capacity construction optimization

In order to ensure that the sealing agent is evenly pushed along the whole invalid circulation part in the fracturing pump injection process, the pump should be stopped to diffuse pressure after the pumping of the plugging agent slug is finished, and the construction displacement pumping of the sealing agent slug is controlled after the artificial crack is fully closed. The stratum rupture pressure of a 1000m deep reservoir stratum of the Daqing Changyuan is generally between 24 and 32MPa, and a test fracturing analysis result shows that when the fracturing construction displacement is lower than 2.0m³At the time of/min, the bottom hole pressure is close to the reservoir fracture pressure, and the fracture extends slowly, so the injection displacement of the sealing agent is designed to be 1.5-2.0 m³And/min. The interpretation curve of the L10-P181 downhole pressure test is shown in FIG. 14.

Fifthly, determining pump injection construction program

The pump injection procedure is shown in table 5.

TABLE 5

Sixthly, mixing and injecting the oil displacement agent and the plugging agent

The oil displacement agent stock solution and water are stirred and mixed by a sand mixing truck according to a certain proportion, and then the target layer position is determined according to a certain using amount by a determined construction displacement and pumping procedure.

The dry powder component of the blocking agent is mixed with water at a polymer preparation station according to different stage design concentrations, then is conveyed to the site through a ground pipeline, and is stirred and mixed with the liquid cross-linking agent through a sand mixer so as to be injected into a target layer according to determined construction discharge capacity and pump injection procedures and determined dosage.

Seventh, fracturing construction effect

The fracturing site construction of the loudspeaker 9-PS2133 well is carried out in 2018, 05, month and 12, and a fracturing construction curve chart of the loudspeaker 9-PS2133 well is shown in figure 15; the fracturing construction dynamics of the Bragg 9-PS2133 well are shown in figure 16. The daily liquid yield of the initial stage after the well pressure is reduced by 163 tons, the water content is reduced by 0.6 percent, the daily oil increase is 0.04 ton, better plugging liquid reduction and water reduction trends are seen, the daily liquid yield is 44.9 tons in 2018 in 12 months, the water content is 94.3 percent, the daily oil yield is 2.57 tons, the production data is obviously improved, the daily liquid yield is reduced by 37.9 tons, the water content is reduced by 3.5 percent, and the daily oil increase is 0.77 ton.

Claims (6)

1. A method for injecting an oil displacement agent and a plugging agent into a thick oil layer by fracturing to drive and wash a low-water-content part and plug a strong washing strip is characterized by comprising the following steps of: the method comprises the following steps:

(1) the target well is preferably selected from the following steps:

comprehensively selecting a target well according to the position of the isolated well point, the combination of well cementation quality, perforation interpretation data, a reservoir stratum fine description result, a fine residual oil research result and reservoir stratum exploitation condition evaluation data;

(2) determining the potential digging time of a target well:

determining the excavation and submergence time according to the optimized dynamic trend, the descending rule and the current production condition of the target well development in the step 1, and selecting the time when the liquid amount is quickly reduced and the liquid supply is nearly insufficient to perform excavation and submergence;

(3) interval-making for the well of interest preferably:

comprehensively optimizing the submerged layer section according to the single-layer jet-opening thickness, the hole seepage condition, the sand body development, the residual oil distribution condition and the single-layer historical utilization condition;

(4) determining a diving scheme:

determining the fracturing half-seam length of the target interval according to the sand body distribution range, the isolated well point position and the residual oil enrichment range of the target interval;

II, calculating the using amount of the fracturing injection flooding fluid according to the injection opening thickness, the porosity and the extraction degree of the target interval;

III, taking 3/4 with the length of the half seam as a support radius, and calculating the single-layer fracturing sand adding scale;

IV, determining a pump injection construction program: determining the number of injection slugs according to the amount of injected displacement fluid, determining a sand adding step according to the size of the sand adding scale, and injecting the displacement fluid firstly and then adding sand for supporting;

(5) carrying out field implementation:

and determining the injection displacement of the flooding fluid according to the field small-scale test ground pressure condition so as to determine a well pump injection construction program to implement corresponding layer construction.

2. The method for flooding and washing low-water-content parts and plugging strong-water-washing strips by injecting an oil-displacing agent and a plugging agent into a thick oil layer by fracturing as claimed in claim 1, characterized in that: the formula for calculating the oil displacement liquid consumption in the step (4) is as follows:

Q=π×r²×H×Φ*β

wherein: r-fracture half-seam length m;

q-amount of flooding fluid m³；

H-the target layer opening thickness m;

phi-oil layer porosity%;

β -volume ratio of target layer.

3. The method for flooding and washing low-water-content parts and plugging strong-water-washing strips by injecting an oil-displacing agent and a plugging agent into a thick oil layer by fracturing as claimed in claim 1, characterized in that: the single-layer fracturing sand adding scale calculation formula of the step (4) is as follows:

q=π×（3r/4）²×h；

wherein: r-fracture half-seam length m;

q-single layer section fracturing sand adding scale m³；

h-fracture horizontal crack height m.

4. The method for flooding and washing low-water-content parts and plugging strong-water-washing strips by injecting an oil-displacing agent and a plugging agent into a thick oil layer by fracturing as claimed in claim 1, characterized in that: the number of the slugs injected with the flooding fluid in the step (4) is more than or equal to 3, and the pump stopping interval time among the slugs is more than or equal to 10 minutes.

5. The method for flooding and washing low-water-content parts and plugging strong-water-washing strips by injecting an oil-displacing agent and a plugging agent into a thick oil layer by fracturing as claimed in claim 1, characterized in that: the flooding liquid in the step (4) comprises a surfactant and water; the volume percentage of the surfactant is 0.6 percent and the volume percentage of the water is 100 percent.

6. The method for flooding and washing low-water-content parts and plugging strong-water-washing strips by injecting an oil-displacing agent and a plugging agent into a thick oil layer by fracturing as claimed in claim 5, wherein the method comprises the following steps: the water is clear water or sewage after oil field treatment; the surfactant is petroleum sulfonate or HLX surfactant.

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