1. The cross-linked particle plugging agent is characterized by comprising a reagent A, a reagent B, an initiator and a cross-linking agent, wherein the reagent A comprises polyacrylamide, clay, water, acrylamide and acrylic acid, and the reagent B comprises acrylic acid a and a NaOH aqueous solution;

the mass ratio of polyacrylamide, clay, water, acrylamide, acrylic acid, a cross-linking agent and an initiator is 0.006: 0.25: 3: 1: 0.006: 0.002: 0.002;

the volume ratio of the acrylic acid a to the NaOH aqueous solution is 10: 1;

the volume ratio of water to the NaOH aqueous solution is 3: 1.

2. the cross-linked particle plugging agent suitable for the high-water-cut horizontal well of the low-permeability reservoir as claimed in claim 1, wherein the saturation degree of the NaOH aqueous solution is 0.75, the cross-linking agent is N-N methylene bisacrylamide, and the initiator is ammonium persulfate.

3. A preparation method of a cross-linked particle plugging agent suitable for a low-permeability reservoir high-water-content horizontal well is characterized by comprising the following steps:

step 1, adding polyacrylamide and clay into normal-temperature water, uniformly stirring, adding acrylamide and acrylic acid, uniformly stirring, and standing for 10min to obtain a reagent A;

step 2, adding acrylic acid a into NaOH aqueous solution, continuously stirring until no colloid exists, and standing for 5min to obtain a reagent B;

and 3, mixing the reagent A obtained in the step 1 and the reagent B obtained in the step 2, stirring until no precipitate exists, adding an initiator and a cross-linking agent after standing, heating and stirring in a water bath by using a constant-temperature heating stirrer, and obtaining the cross-linked particle plugging agent after the reaction is completed.

4. The preparation method of the cross-linked particle plugging agent suitable for the high-water-cut horizontal well of the low-permeability reservoir according to claim 1, wherein in the step 1, the mass ratio of polyacrylamide to clay to water to acrylamide to acrylic acid is 0.006: 0.25: 3: 1: 0.006.

5. the preparation method of the cross-linked particle plugging agent suitable for the high-water-cut horizontal well of the low-permeability reservoir according to claim 1, wherein in the step 2, the volume ratio of the acrylic acid a to the NaOH aqueous solution is 10: 1.

6. The method for preparing the cross-linked particle plugging agent suitable for the high-water-cut horizontal well of the low-permeability reservoir according to the claim 1, wherein in the step 2, the saturation degree of the NaOH aqueous solution is 0.75.

7. The preparation method of the cross-linked particle plugging agent suitable for the high-water-cut horizontal well of the low-permeability reservoir according to claim 1, wherein the volume ratio of water to NaOH aqueous solution is 3: 1.

8. the preparation method of the cross-linked particle plugging agent suitable for the high-water-cut horizontal well of the low-permeability reservoir according to claim 1, wherein in the step 3, the standing time is 3min, the water bath heating temperature is 70 ℃, and the water bath stirring time is 5 min.

9. The preparation method of the cross-linked particle plugging agent suitable for the high-water-cut horizontal well of the low-permeability reservoir according to claim 1, wherein the mass ratio of the polyacrylamide to the cross-linking agent to the initiator is 3: 1: 1.

10. the preparation method of the cross-linking particle plugging agent applicable to the high-water-cut horizontal well of the low-permeability reservoir according to claim 1, wherein the cross-linking agent is N-N methylene bisacrylamide, and the initiator is ammonium persulfate.

Background

After the development of oil fields enters the middle and later stages, the high water content or the rapid water content rise of the horizontal well is one of the commonly encountered problems, and the productivity loss is serious. The efficient water plugging process has important significance for ensuring normal production of an oil well. At present, the most widely applied water plugging process of each large oil field is a mechanical water plugging method, the operation is complex, and the water plugging effect cannot meet the treatment requirement of the block. On the basis of mechanical water plugging, the bidirectional plugging adjustment is further performed on the oil-water well, the effective period of water plugging is prolonged, and the water plugging effect is improved. The chemical water plugging has good adaptability to water plugging in old areas in water injection development blocks, can effectively reduce water content, and improves the single-well productivity. The selection of the formula of the plugging agent is a crucial part of chemical water plugging, the currently commonly used chemical plugging agents mainly comprise a jelly type, a resin type, a gel type, a precipitation type and a dispersion type, and the advantages and the disadvantages of various plugging agent systems are obvious: (1) the jelly glue type has the advantages of different flow resistance to oil and water, adjustable freezing time, capability of plugging different depths, and the defects of poor stability at higher temperature and mineralization and higher toxicity of common cross-linking agents; (2) the resin type has the advantages of good injectability, temperature resistance, salt resistance, high strength, long validity period and high cost; (3) the gel type has the advantages of good injectability, no pollution to the environment, adjustable gel time, capability of plugging different depths and low strength and no scouring resistance; (4) the precipitation type has the advantages of temperature resistance, salt resistance, capability of plugging different depths, low strength, large dosage and high cost; (5) the dispersion type has the advantages of high temperature resistance, salt resistance and plugging capability of the solid dispersion type, has selectivity to oil and water in a gas and gel dispersion type, and has the defect that the gas dispersion type needs a gas source and power consumption. Particularly, the amount of injected water into a horizontal well in a low-permeability reservoir fracture development area is large, and no single system can meet the water plugging requirement. Therefore, a plugging agent suitable for the high water content of the horizontal well of the low-permeability reservoir is needed to be provided, and technical support is provided for oil stabilization and water control of the oil field.

Disclosure of Invention

The invention aims to provide a cross-linked particle plugging agent suitable for a high-water-content horizontal well of a low-permeability reservoir, and solves the problem that the water plugging effect of the existing plugging agent is not ideal.

The invention also aims to provide a preparation method of the cross-linked particle plugging agent suitable for a low-permeability reservoir high-water-cut horizontal well.

The technical scheme adopted by the invention is that the cross-linked particle plugging agent suitable for the high-water-content horizontal well of the low-permeability oil reservoir comprises a reagent A, a reagent B, an initiator and cross-linking agent components, wherein the reagent A comprises polyacrylamide, clay, water, acrylamide and acrylic acid, and the reagent B comprises acrylic acid a and NaOH aqueous solution;

the mass ratio of polyacrylamide, clay, water, acrylamide, acrylic acid, a cross-linking agent and an initiator is 0.006: 0.25: 3: 1: 0.006: 0.002: 0.002;

the volume ratio of the acrylic acid a to the NaOH aqueous solution is 10: 1;

the volume ratio of water to the NaOH aqueous solution is 3: 1.

the present invention is also characterized in that,

the saturation degree of the NaOH aqueous solution is 0.75, the cross-linking agent is N-N methylene bisacrylamide, and the initiator is ammonium persulfate.

The invention adopts another technical scheme that a preparation method of the cross-linked particle plugging agent suitable for a low-permeability reservoir high-water-content horizontal well is implemented according to the following steps:

step 1, adding polyacrylamide and clay into normal-temperature water, uniformly stirring, adding acrylamide and acrylic acid, uniformly stirring, and standing for 10min to obtain a reagent A;

step 2, adding acrylic acid a into NaOH aqueous solution, continuously stirring until no colloid exists, and standing for 5min to obtain a reagent B;

and 3, mixing the reagent A obtained in the step 1 and the reagent B obtained in the step 2, stirring until no precipitate exists, adding an initiator and a cross-linking agent after standing, heating and stirring in a water bath by using a constant-temperature heating stirrer, and obtaining the cross-linked particle plugging agent after the reaction is completed.

The present invention is also characterized in that,

in the step 1, the mass ratio of polyacrylamide, clay, water, acrylamide and acrylic acid is 0.006: 0.25: 3: 1: 0.006.

in step 2, the volume ratio of acrylic acid a to the NaOH aqueous solution is 10: 1.

In step 2, the saturation of the NaOH aqueous solution was 0.75.

The volume ratio of water to the NaOH aqueous solution is 3: 1.

in step 3, the standing time is 3min, the water bath heating temperature is 70 ℃, and the water bath stirring time is 5 min.

The mass ratio of the polyacrylamide to the cross-linking agent to the initiator is 3: 1: 1.

the cross-linking agent is N-N methylene bisacrylamide, and the initiator is ammonium persulfate.

The beneficial effect of the invention is that,

(1) the cross-linked particle plugging agent prepared by the preparation method of the cross-linked particle plugging agent suitable for the high-water-content horizontal well of the low-permeability reservoir has good temperature resistance, salt resistance and shearing resistance, and has strong water plugging capability;

(2) the plugging agent prepared by the preparation method of the cross-linked particle plugging agent suitable for the low-permeability reservoir high-water-content horizontal well has the plugging rate of over 90 percent and good washout resistance.

Detailed Description

The present invention will be described in detail with reference to the following embodiments.

The invention provides a cross-linked particle plugging agent suitable for a high-water-content horizontal well of a low-permeability oil reservoir, which comprises a reagent A, a reagent B, an initiator and cross-linking agent components, wherein the reagent A comprises polyacrylamide, clay, water, acrylamide and acrylic acid, and the reagent B comprises acrylic acid a and NaOH aqueous solution;

the mass ratio of polyacrylamide, clay, water, acrylamide, acrylic acid, a cross-linking agent and an initiator is 0.006: 0.25: 3: 1: 0.006: 0.002: 0.002;

the volume ratio of the acrylic acid a to the NaOH aqueous solution is 10: 1;

the volume ratio of water to the NaOH aqueous solution is 3: 1;

the saturation degree of the NaOH aqueous solution is 0.75, the cross-linking agent is N-N methylene bisacrylamide, and the initiator is ammonium persulfate.

The invention provides a preparation method of a cross-linked particle plugging agent suitable for a low-permeability oil reservoir high-water-content horizontal well, which is implemented according to the following steps:

step 1, adding polyacrylamide and clay into normal-temperature water, uniformly stirring, adding acrylamide and acrylic acid, uniformly stirring, and standing for 10min to obtain a reagent A;

wherein the mass ratio of polyacrylamide, clay, water, acrylamide and acrylic acid is 0.006: 0.25: 3: 1: 0.006;

step 2, adding acrylic acid a into NaOH aqueous solution, continuously stirring until no colloid exists, and standing for 5min to obtain a reagent B;

the volume ratio of the acrylic acid a to the NaOH aqueous solution is 10: 1; the saturation degree of the NaOH aqueous solution is 0.75; the volume ratio of water to the NaOH aqueous solution is 3: 1;

step 3, mixing the reagent A obtained in the step 1 and the reagent B obtained in the step 2, stirring until no precipitate exists, standing for 3min, adding an initiator and a crosslinking agent, heating and stirring in a water bath at 70 ℃ for 5min by using a constant-temperature heating stirrer, and obtaining a crosslinked particle plugging agent after complete reaction;

wherein the mass ratio of the polyacrylamide to the cross-linking agent to the initiator is 3: 1: 1; the cross-linking agent is N-N methylene bisacrylamide, and the initiator is ammonium persulfate.

The working principle of the invention is as follows: after the cross-linked particle plugging agent is injected into a stratum, flexible particles deform under the action of pressure to enter the stratum, the particles expand three to six times in volume after absorbing water to plug a crack water channeling channel, the particles are transferred to the stratum with medium and low permeability under the action of injection water pressure to displace low-permeability block liquid, a dynamic pressure field at the bottom of a well is changed, the pore throat of a high-permeability crack is plugged, the flow of the injected water is changed, and the effective swept volume is improved. Wherein, the cross-linked polymer gel injected in advance plays roles of adhesion and blocking by establishing a blocking framework, forces the subsequent liquid flow to turn, and further enhances the water blocking capability of the blocking agent.

Examples

Step 1, adding 0.3g of polyacrylamide and 12.5g of clay into 150ml of normal-temperature water, uniformly stirring, adding 50g of acrylamide and 0.3g of acrylic acid, uniformly stirring, and standing for 10min to obtain a reagent A;

step 2, adding 5ml of acrylic acid a into 50ml of 0.75 saturation NaOH aqueous solution, continuously stirring until no jelly exists, and standing for 5min to obtain a reagent B;

step 3, mixing the reagent A obtained in the step 1 and the reagent B obtained in the step 2, stirring until no precipitate exists, standing for 3min, adding 0.1g of ammonium persulfate and 0.1g of N-N methylene bisacrylamide, heating and stirring in a water bath at 70 ℃ for 5min by using a constant-temperature heating stirrer, and obtaining the cross-linked particle plugging agent after complete reaction;

the field implementation effect is as follows: the X well is put into production in 2012 in 10 and 2 months, and the 3 balance average daily production liquid before the putting into production is 16.67m³3.54t of daily oil, 73.2 percent of water; after 25 days of operation, 3.12t of oil is produced daily and 75.8 percent of water is contained; water content mutation from 3 months and 1 day to 5 days in 2013 to 85.0 percent of daily juice 16.2m³9824 PPM; cut-off test time, daily product liquor 6.27m³84.4% of water; the plugging agent of the invention is used for experimental water plugging of the well.

The construction parameters are as follows: (1) injection pressure: 16.32 MPa; (2) injection flow rate: 5m³H; (3) the dosage of the plugging agent is as follows: 1300m³。

The concrete slug mode is as follows: a first section plug: the cross-linked particle plugging agent is injected to block large pores of cracks, so that the subsequent gel plugging agent is prevented from being extruded into a horizontal well, and 600m is injected³A cross-linked particulate plugging agent; a second slug: injecting the existing cross-linked gel plugging agent to block the gaps of the particles and the high-permeability pores and cracks, plugging the cracks of the water injection well which are likely to generate cross flow, and injecting the plugging agent into the water injection well for 700m³And (3) a cross-linked gel plugging agent. After the water plugging construction is carried out on the well, the water content is reduced to 70.3%, the oil production is obviously improved, the working fluid level is reduced, the daily oil increase is 2.03t, and the application effect of the plugging agent is good.