A method for plugging the channeling of a production well after ASP flooding

Abstract

The method for plugging the channeling of the production well after the ASP flooding relates to the field of oilfield development, and solves the problems of serious formation pollution, casing damage and poor long-term plugging stability caused by the channeling plugging agent used in the existing plugging method. The method comprises the following steps: S1: selecting a channeling plugging well and determining a channeling plugging layer; S2: preparing a temporary plugging agent system according to the well condition, injecting the temporary plugging agent into a low-permeability layer, and controlling the gel breaking time of the temporary plugging agent; S3: injecting a channeling plugging agent into a high-permeability layer of the channeling plugging well; S4: injecting a sealing agent into the channeling plugging well; S5: performing a test injection on the channeling plugging well, measuring the injection volume of the layer, performing a production profile test, and then opening the well for production. The method does not pollute the formation and has low casing damage, and the channeling plugging agent system can ensure the long-term stability in the ASP flooding environment after plugging the channeling position of the production well after the ASP flooding, the plugging effect is continuous and effective, the daily liquid production and water content are significantly reduced, and the daily oil production is significantly increased.

Description

Technical Field

[0001] This invention relates to the field of oilfield development technology, and in particular to a method for plugging crossflow in production wells after ternary composite flooding. Background Technology

[0002] Currently, the commonly used chemical plugging method for production wells involves injecting cement-based or cyanide-based plugging agents into the channeling formations under certain injection pressure conditions to plug the deep and near-wellbore areas of the channeling formations. This method causes severe formation contamination, damages the casing, and is costly. Furthermore, the plugging agents used in this method, after prolonged contact with the post-flooding environment of ternary composite materials, undergo embrittlement and cracking, reducing the plugging and channeling strength and significantly impacting long-term stability. Summary of the Invention

[0003] This invention addresses the problems of existing plugging methods using channeling agents that cause severe formation contamination, casing damage, and poor long-term stability. It provides a method for plugging channeling in production wells after ternary composite flooding. This method does not contaminate the formation, causes minimal casing damage, and has controllable costs. Furthermore, after the channeling agent system enters the formation and plugs the channeling sites in the production well after ternary composite flooding, its long-term stability in the ternary flooding fluid environment is guaranteed, resulting in sustained and effective plugging, a significant decrease in daily fluid production and water cut, and a significant increase in daily oil production.

[0004] The present invention solves its problem through the following technical solution: The method for plugging crossflow in production wells after ternary composite flooding includes the following steps:

[0005] S1: Select the well to be sealed and determine the sealing layer;

[0006] S2: Based on the well conditions, prepare a temporary plugging agent system, inject the temporary plugging agent into the low-permeability layer, and control the breaking time of the temporary plugging agent;

[0007] S3: After the temporary plugging agent is injected into the low-permeability layer, the plugging and sealing agent is injected into the high-permeability layer of the well to be sealed.

[0008] S4: After the sealing and plugging agent is injected, the sealing agent is injected into the well to be sealed.

[0009] S5: After conducting a test injection of the sealed well, measuring the injection volume of the layer, and testing the production profile, the well is opened for production.

[0010] Furthermore, in step S1, the method for selecting wells to seal off the flow channels is as follows: in well areas with well-developed river sand, good connectivity, perfect injection-production relationship and a certain pressure space, production wells with successor layers, significant differences in oil saturation or water flooding between layers, dominant seepage channels and serious inefficient and ineffective circulation are preferred.

[0011] Furthermore, step S1 determines the sealing layer by selecting a layer with an effective thickness of more than 2m, a permeability greater than the average level of the whole area, and a high water flooding layer thickness ratio of less than 60% as the sealing layer.

[0012] Furthermore, the temporary plugging agent system in step S2 includes a polymer, a crosslinking agent, a depolymerizer, and a stabilizer;

[0013] The polymer is partially hydrolyzed polyacrylamide; molecular weight 3 million to 25 million, degree of hydrolysis 1% to 18%, concentration: 0.3-0.5%;

[0014] The crosslinking agent is an organic chromium crosslinking agent, which is chromium lactate or chromium acetate; the ratio of the amount of polymer and crosslinking agent can be expressed by the crosslinking ratio, which is between 20:1 and 60:1.

[0015] The degreasing agent is potassium permanganate or sodium hypochlorite, with a concentration of 0.01-0.02%;

[0016] The stabilizer is urea, with a concentration of 0.02-0.04%;

[0017] Furthermore, the preparation method of the temporary plugging agent includes the following steps:

[0018] c1. Dissolve 0.3% to 0.5% of partially hydrolyzed polyacrylamide in water at room temperature by stirring.

[0019] c2. Add the crosslinking agent to the solution obtained in c1 and stir to dissolve;

[0020] c3. Add 0.01% to 0.02% of the decolloid to the solution obtained in c2 and stir to dissolve;

[0021] c4. Add 0.02% to 0.04% of stabilizer to the solution obtained in c3 and stir until completely dissolved to obtain the temporary plugging agent.

[0022] Furthermore, the method for injecting the blocking and channeling agent in step S3 is as follows: the injection pressure is slowly increased by varying the injection volume and concentration; the specific method includes:

[0023] First, inject 1000 mg / L of plugging and channeling agent. If the injection pressure rises rapidly, reduce the concentration of the plugging and channeling agent to 500 mg / L. If the pressure continues to rise, reduce the daily injection volume of the plugging and channeling agent. If the injection pressure rises slowly, increase the concentration of the plugging and channeling agent to 1500–3000 mg / L. The injection pressure is then increased slowly by varying the injection volume and concentration.

[0024] Furthermore, the rapid increase in injection pressure refers to a pressure increase of more than 1.0 MPa within 5 days;

[0025] Slow pressure rise refers to a pressure increase of less than 1.0 MPa within 5 days.

[0026] Furthermore, the method for determining the injection volume of the plugging and blocking agent in step S3 is as follows:

[0027] The sealing agent is designed to have a sealing radius depth of 10m and a sealing thickness that is half the thickness of the high-water-flooding layer.

[0028] The dosage of the blocking agent is calculated using the injection volume formula of the blocking agent;

[0029] The injection volume formula for the blocking and intercepting agent is as follows:

[0030]

[0031] Among them: Q 封窜剂 —Injection volume of the blocking and intercepting agent, m 3 ;R 封窜 —The sealing radius is a fixed value of 10m; H 水淹 —Thickness of the high-water-flooded layer, m; φ—Porosity of the sealing layer, %;

[0032] Substituting the sealing radius of 10m into the formula, the simplified formula for calculating the amount of sealing agent injected is obtained as follows:

[0033] Q 封窜剂 =50×π×H 水淹 ×φ.

[0035] Furthermore, the daily dosage of the sealing and blocking agent is designed, and the construction period is calculated based on the injection volume and daily dosage of the sealing and blocking agent.

[0036] The daily dosage of the blocking and intercepting agent is designed to be 30-70 mg / day. 3 .

[0037] Furthermore, the blocking agent is an alkali-resistant multi-component complex gel blocking agent;

[0038] The alkali-resistant multi-component complexing gel blocking agent is made of partially hydrolyzed polyacrylamide, organic chromium crosslinking agent, thiourea stabilizer and water; the mass ratio of partially hydrolyzed polyacrylamide, organic chromium crosslinking agent and thiourea stabilizer is 0.05-0.3% : 0.2-0.35% : 0.04-0.08%;

[0039] The partially hydrolyzed polyacrylamide has a molecular weight of 3 million to 25 million and a degree of hydrolysis of 1% to 18%; the organic chromium crosslinking agent is chromium lactate or chromium acetate.

[0040] Furthermore, the preparation method of the alkali-resistant multi-component complexed gel blocking and channeling agent includes the following steps:

[0041] b1. Dissolve 0.05% to 0.3% of partially hydrolyzed polyacrylamide in water at room temperature by stirring.

[0042] b2. Add 0.2-0.35% of organic chromium crosslinking agent to the solution obtained in step b1 and stir to dissolve;

[0043] b3. Add 0.04% to 0.08% of a stabilizer to the solution obtained in step b2 to obtain the temporary plugging agent.

[0044] Furthermore, the sealing agent in step S4 is a micro-expansion type sealing agent; the micro-expansion type sealing agent is composed of the following components by weight percentage:

[0045] 14%–17% main agent; 0.3%–0.4% crosslinking agent; 0.15%–0.18% reinforcing agent; 4%–9% micro-expansion additive; balance: water;

[0046] The main agent is a mixture of irradiated acrylamide and bentonite;

[0047] The micro-expansion additive is OP-10 or sodium dodecylbenzenesulfonate;

[0048] The crosslinking agent is one or a mixture of sodium persulfate and potassium persulfate;

[0049] The reinforcing agent is N,N-methylenebisacrylamide.

[0050] Furthermore, the preparation method of the micro-expansion plugging agent includes the following steps:

[0051] a1. Dissolve the main agent in 14%–17% water at room temperature by stirring.

[0052] a2. Add 0.3% to 0.4% of crosslinking agent to the solution obtained in step a1 and stir to dissolve;

[0053] a3. Add 0.15% to 0.18% of the reinforcing agent to the solution obtained in step a2 and stir to dissolve;

[0054] a4. Add 4% to 9% of the micro-expansion additive to the solution obtained in step a3 and stir until completely dissolved to obtain the micro-expansion type sealing agent.

[0055] Furthermore, the method for determining the amount of sealing agent injected in step S4 includes the following steps:

[0056] The sealing agent is designed to have a sealing radius of 2 meters, with a 2-meter oil drainage channel reserved.

[0057] Calculate the amount of sealing agent to be injected using a formula;

[0058] The formula for calculating the amount of sealing agent injected is as follows:

[0059]

[0060] Among them: Q 封口剂 —The amount of sealing agent injected, m 3 ;R 封口 —The sealing radius of the sealant is a fixed value of 2m; R 泄油 —The radius of the oil drain channel is a fixed value of 2m; H 水淹 —Thickness of the high-water-flooded layer, m; φ—Porosity of the sealing layer, %;

[0061] R 封口 For fixed values ​​2m and R 泄油 Substituting the fixed value 2m into the formula, we obtain the simplified formula for the sealing agent injection amount:

[0062] Q 封口剂 =6×π×H 水淹 ×φ.

[0064] Furthermore, in step S4, a sealing agent is injected into the well to seal the blockage. During the injection, the injection rate and injection pressure are accurately recorded, and the well is shut in under pressure for 24 hours to allow the sealant to solidify.

[0065] Compared with the above-mentioned background technology, the present invention has the following beneficial effects:

[0066] The present invention provides a method for sealing crossflow in production wells after ternary composite flooding, which does not pollute the formation, causes minimal damage to the casing, and has controllable costs. The water-blocking and crossflow-sealing agent used in this invention is in contact with the ternary composite flooding environment for a long time without a decrease in sealing and crossflow-sealing strength, ensuring the long-term stability of the sealing and crossflow-sealing effect. Attached Figure Description

[0067] Figure 1 This is a flowchart of a method for sealing crossflow in a production well after ternary composite flooding according to the present invention. Detailed Implementation

[0068] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0069] like Figure 1 As shown, this invention discloses a method for plugging crossflow in a production well after ternary composite flooding. The method mainly includes the following steps:

[0070] S1: Select the well to be sealed and determine the sealing layer;

[0071] a. Selection of wells for sealing: In well areas with well-developed river sand, good connectivity, perfect injection-production relationship and a certain pressure space, production wells with successor layers, significant differences in oil saturation or water flooding between layers, dominant seepage channels and serious inefficient and ineffective circulation are preferred.

[0072] b. Determine the sealing layer: Select the layer with an effective thickness of more than 2m, a permeability greater than the average level of the whole area, and a high water flooding layer thickness ratio of less than 60% as the sealing layer;

[0073] S2: Depending on the well conditions, inject the temporary plugging agent into the low-permeability layer and control the breaking time of the temporary plugging agent;

[0074] Prepare 10-30m according to well conditions. 3 The temporary plugging agent system involves injecting the temporary plugging agent into a low-permeability layer and controlling the break-off time of the temporary plugging agent.

[0075] The temporary plugging agent system includes a polymer, a crosslinking agent, a desiccant, and a stabilizer;

[0076] The polymer is partially hydrolyzed polyacrylamide; molecular weight 3 million to 25 million, degree of hydrolysis 1% to 18%, concentration: 0.3% to 0.5%;

[0077] The crosslinking agent is an organic chromium crosslinking agent, which is chromium lactate or chromium acetate; the ratio of the amount of polymer and crosslinking agent can be expressed by the crosslinking ratio, which is between 20:1 and 60:1.

[0078] The degreasing agent is potassium permanganate or sodium hypochlorite, with a concentration of 0.01-0.02%;

[0079] The stabilizer is urea, with a concentration of 0.02-0.04%;

[0080] The preparation method of the temporary plugging agent includes the following steps:

[0081] a. Dissolve 0.3%–0.5% of partially hydrolyzed polyacrylamide in water at room temperature by stirring.

[0082] b. Add the crosslinking agent to the solution obtained in step a and stir to dissolve;

[0083] c. Add 0.01% to 0.02% of the decolloid to the solution obtained in step b and stir to dissolve;

[0084] d. Add 0.02% to 0.04% of stabilizer to the solution obtained in step c and stir until completely dissolved to obtain the temporary plugging agent.

[0085] S3: After the temporary plugging agent is injected into the low-permeability layer, the plugging and sealing agent is injected into the high-permeability layer of the well to be sealed.

[0086] 3.1 Preparation of blocking and channeling agents;

[0087] The blocking and channeling agent is an alkali-resistant multi-component complex gel-type blocking and channeling agent;

[0088] The alkali-resistant multi-component complexing gel blocking agent is made of partially hydrolyzed polyacrylamide, organic chromium crosslinking agent, thiourea stabilizer and water; the mass ratio of partially hydrolyzed polyacrylamide, organic chromium crosslinking agent and thiourea stabilizer is 0.05-0.3% : 0.2-0.35% : 0.04-0.08%;

[0089] The partially hydrolyzed polyacrylamide has a molecular weight of 3 million to 25 million and a degree of hydrolysis of 1% to 18%.

[0090] The organic chromium crosslinking agent is chromium lactate or chromium acetate;

[0091] The preparation method of the alkali-resistant multi-component complexed gel blocking and channeling agent includes the following steps:

[0092] a. Dissolve 0.05%–0.3% of partially hydrolyzed polyacrylamide in water at room temperature by stirring.

[0093] b. Add 0.2-0.35% of the organic chromium crosslinking agent to the solution obtained in step a and stir to dissolve;

[0094] c. Add 0.04% to 0.08% of a stabilizer to the solution obtained in step b to obtain the temporary plugging agent.

[0095] 3.2 The alkali-resistant multi-component complexed gel-type sealing agent is designed with a sealing radius depth of 10m and a sealing thickness of half the thickness of the high-water-flooding agent;

[0096] Using formula Calculate the amount of sealing agent injected;

[0097] Among them: Q 封窜剂 —Injection volume of the blocking and intercepting agent, m 3 ;R 封窜 —The sealing radius is a fixed value of 10m; H 水淹 —Thickness of the high-water-flooded layer, m; φ—Porosity of the sealing layer, %.

[0098] The formula for calculating the amount of sealing agent injected can be simplified to: Q 封窜剂 =50×π×H 水淹 ×φ.

[0099] The daily dosage of the alkali-resistant multi-component complexed gel plugging and sealing agent is designed to be 30–70 mg / L. 3 The construction period is calculated based on the amount of sealing agent injected and the daily mixing volume.

[0100] 3.3. For wells designed to prevent channeling, inject an alkali-resistant multi-component complex gel plugging agent. The injection method is as follows:

[0101] First, inject 1000 mg / L of plugging and channeling agent. If the injection pressure rises rapidly (pressure rise greater than 1.0 MPa within 5 days), reduce the concentration of the plugging and channeling agent to 500 mg / L. If the pressure continues to rise, reduce the daily injection volume of the plugging and channeling agent. If the injection pressure rises slowly (pressure rise less than 1 MPa within 5 days), increase the concentration of the plugging and channeling agent to 1500–3000 mg / L. The injection pressure is gradually increased by varying the injection volume and concentration.

[0102] S4: After the sealing and plugging agent is injected, the sealing agent is injected into the well to be sealed.

[0103] 4.1. A micro-expansion plugging agent is prepared as a sealing agent. The plugging agent is composed of the following components by weight percentage: main agent: 14%~17%, crosslinking agent: 0.3%~0.4%, reinforcing agent: 0.15%~0.18%, micro-expansion additive: 4%~9%, and the balance is water. The micro-expansion plugging agent and its preparation method have been patented, patent number ZL 201910727723.4; patent title: "A micro-expansion plugging agent and its preparation method".

[0104] 4.2 The sealing radius of the sealant is designed to be 2 meters, with a 2-meter oil drainage channel reserved. The formula is used... Calculate the amount of sealing agent to be injected;

[0105] Among them: Q 封口剂 —The amount of sealing agent injected, m 3 ;R 封口 —The sealing radius of the sealant is a fixed value of 2m; R 泄油 —The radius of the oil drain channel is a fixed value of 2m; H 水淹 —Thickness of the high-water-flooded layer, m; φ—Porosity of the sealing layer, %.

[0106] The formula for calculating the amount of sealing agent injected can be simplified to: Q 封口剂 =6×π×H 水淹 ×φ.

[0107] 4.3. Inject sealing agent into the well to seal the blockage. During the injection, accurately record the injection rate and injection pressure, and shut in the well under pressure for 24 hours to allow it to solidify.

[0108] S5: After conducting a test injection of the sealed well, measuring the injection volume of the layer, and testing the production profile, the well is opened for production.

[0109] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings, using a field example from Daqing Oilfield.

[0110] Example 1

[0111] a. Select well 1 for sealing / transferring;

[0112] b. Determine the sealing layer P1;

[0113] c. Prepare 10m according to well conditions. 3 The temporary plugging agent system involves injecting the temporary plugging agent into a low-permeability layer and controlling the break-off time of the temporary plugging agent.

[0114] The temporary plugging agent system includes a polymer, a crosslinking agent, a desiccant, and a stabilizer;

[0115] The polymer is partially hydrolyzed polyacrylamide; molecular weight 3 million to 25 million, degree of hydrolysis 1% to 18%, concentration: 0.3% to 0.5%;

[0116] The crosslinking agent is an organic chromium crosslinking agent, which is chromium lactate or chromium acetate; the ratio of the amount of polymer and crosslinking agent can be expressed by the crosslinking ratio, which is 20:1-60:1.

[0117] The degreasing agent is potassium permanganate or sodium hypochlorite, with a concentration of 0.01-0.02%;

[0118] The stabilizer is urea, with a concentration of 0.02-0.04%;

[0119] The preparation method of the temporary plugging agent includes the following steps:

[0120] c1. Dissolve 0.3% to 0.5% of partially hydrolyzed polyacrylamide in water at room temperature by stirring.

[0121] c2. Add the crosslinking agent to the solution obtained in step c1 and stir to dissolve;

[0122] c3. Add 0.01% to 0.02% of the decolloid to the solution obtained in step c2 and stir to dissolve;

[0123] c4. Add 0.02% to 0.04% of stabilizer to the solution obtained in step c3 and stir until completely dissolved to obtain the temporary plugging agent.

[0124] d. Preparation of alkali-resistant multi-component complexed gel-type blocking and channeling agent;

[0125] The alkali-resistant multi-component complexing gel blocking agent is made of partially hydrolyzed polyacrylamide, organic chromium crosslinking agent, thiourea stabilizer and water; the mass ratio of partially hydrolyzed polyacrylamide, organic chromium crosslinking agent and thiourea stabilizer is 0.05-0.3% : 0.2-0.35% : 0.04-0.08%;

[0126] The partially hydrolyzed polyacrylamide has a molecular weight of 3 million to 25 million and a degree of hydrolysis of 1% to 18%; the organic chromium crosslinking agent is chromium lactate or chromium acetate.

[0127] The preparation method of the alkali-resistant multi-component complexed gel blocking and channeling agent includes the following steps:

[0128] d1. Dissolve 0.05%–0.3% of partially hydrolyzed polyacrylamide in water at room temperature by stirring.

[0129] d2. Add 0.2-0.35% of organic chromium crosslinking agent to the solution obtained in step d1 and stir to dissolve;

[0130] d3. Add 0.04% to 0.08% of a stabilizer to the solution obtained in step d2 to obtain the temporary plugging agent.

[0131] e. The alkali-resistant multi-component complexed gel-type sealing agent is designed with a sealing radius depth of 10m, a high water flooding thickness of 6.8m, a porosity of 29.1% in the sealing layer, and a sealing agent dosage of Q. 封窜剂 =50×π×H 水淹 ×φ=50×3.14×6.8×0.291=310m 3 The daily injection volume is designed to be 40-70m³. 3 The construction period is 5-8 days;

[0132] f. Inject alkali-resistant multi-component complex gel plugging and sealing agent into the well to be sealed. First, inject 1000 mg / L of the plugging and sealing agent, and slowly increase the injection pressure (to 0.6 MPa within 5 days), then increase the gel concentration to 1500 mg / L. The injection pressure is slowly increased by varying the injection volume and concentration.

[0133] g. Prepare a micro-expansion plugging agent as a sealing agent, and prepare the sealing agent according to the patent number ZL 201910727723.4 "A micro-expansion plugging agent and its preparation method";

[0134] h. Design the sealing agent to have a sealing radius of 2 meters, and reserve a 2-meter oil drainage channel. The amount of sealing agent used is Q. 封口剂 =6×π×H 水淹 ×φ=6×3.14×6.8×0.291=37m 3 ;

[0135] i. Inject sealing agent into the well to seal the blockage. During the injection, accurately record the injection volume and injection pressure, and shut the well under pressure for 24 hours to allow it to solidify.

[0136] j. After conducting a test injection of the sealed well, measuring the injection volume of each layer, and performing a production profile test, the well is opened for production.

[0137] Test Example 1

[0138] After plugging using the method in Example 1, the daily fluid production of a single well increased from 48m³. 3 Dropped to 37m 3Daily oil production increased by 2.28 tons, and water content decreased by 6.2 percentage points, with good results from the field test.

[0139] Example 2

[0140] a. Select well 2 for sealing;

[0141] b. Determine the sealing layer P2;

[0142] c. Prepare 20m according to well conditions. 3 The temporary plugging agent system (preparation method is the same as in Example 1) involves injecting the temporary plugging agent into a low-permeability layer and controlling the breaking time of the temporary plugging agent.

[0143] d. Preparation of alkali-resistant multi-component complexed gel-type blocking and channeling agent (preparation method is the same as in Example 1);

[0144] e. The alkali-resistant multi-component complexed gel-type sealing agent is designed with a sealing radius depth of 10m, a high water flooding thickness of 9.6m, a porosity of 29.9% in the sealing layer, and a sealing agent dosage of Q. 封窜剂 =50×π×H 水淹 ×φ=50×3.14×9.6×0.299=450m 3 The daily injection volume is designed to be 30-60m³. 3 The construction period is 8 to 15 days;

[0145] f. Inject alkali-resistant multi-component complex gel plugging and sealing agent into the well to be sealed. First, inject 1000 mg / L of the plugging and sealing agent, and the injection pressure rises rapidly (to 1.3 MPa within 5 days). Then, reduce the gel concentration to 500 mg / L. By varying the injection volume and concentration, the injection pressure is increased slowly.

[0146] g. Prepare a micro-expansion type sealing agent as a sealing agent (preparation method is the same as in Example 1);

[0147] h. Design the sealing agent to have a sealing radius of 2 meters, and reserve a 2-meter oil drainage channel. The amount of sealing agent used is Q. 封口剂 =6×π×H 水淹 ×φ=6×3.14×9.6×0.299=54m 3 ;

[0148] i. Inject sealing agent into the well to seal the blockage. During the injection, accurately record the injection volume and injection pressure, and shut the well under pressure for 24 hours to allow it to solidify.

[0149] j. After conducting a test injection of the sealed well, measuring the injection volume of each layer, and performing a production profile test, the well is opened for production.

[0150] Test Example 2

[0151] After plugging using the method in Example 2, the daily fluid production of a single well increased from 55m³.3 Reduced to 34m 3 Daily oil production increased by 3.58 tons, and water content decreased by 8.7 percentage points, with good results from the field test.

[0152] Example 3

[0153] a. Select well 3 for sealing;

[0154] b. Determine the sealing layer P3;

[0155] c. Prepare 30m according to well conditions. 3 The temporary plugging agent system (preparation method is the same as in Example 1) involves injecting the temporary plugging agent into a low-permeability layer and controlling the breaking time of the temporary plugging agent.

[0156] d. Preparation of alkali-resistant multi-component complexed gel-type blocking and channeling agent (preparation method is the same as in Example 1);

[0157] e. The alkali-resistant multi-component complexed gel-type sealing agent is designed with a sealing radius depth of 10m, a high water flooding thickness of 13.6m, a porosity of 30.5% in the sealing layer, and a sealing agent dosage of Q. 封窜剂 =50×π×H 水淹 ×φ=50×3.14×13.6×0.305=651m 3 The daily injection volume is designed to be 40-70m³. 3 The construction period is 10 to 17 days;

[0158] f. Inject alkali-resistant multi-component complex gel plugging and sealing agent into the well to be sealed. First, inject 1000 mg / L of the plugging and sealing agent, and slowly increase the injection pressure (to 0.8 MPa within 5 days), then increase the gel concentration to 3000 mg / L. The injection pressure is slowly increased by varying the injection volume and concentration.

[0159] g. Prepare a micro-expansion type sealing agent as a sealing agent (preparation method is the same as in Example 1). The sealing agent is composed of the following components by weight percentage: main agent: 17%, crosslinking agent: 0.4%, reinforcing agent: 0.18%, micro-expansion additive: 9%, and the balance is water;

[0160] h. Design the sealing agent to have a sealing radius of 2 meters, and reserve a 2-meter oil drainage channel. The amount of sealing agent used is Q. 封口剂 =6×π×H 水淹 ×φ=6×3.14×13.6×0.305=78m 3 ;

[0161] i. Inject sealing agent into the well to seal the blockage. During the injection, accurately record the injection volume and injection pressure, and shut the well under pressure for 24 hours to allow it to solidify.

[0162] j. After conducting a test injection of the sealed well, measuring the injection volume of each layer, and performing a production profile test, the well is opened for production.

[0163] Test Example 3

[0164] After plugging using the method in Example 3, the daily fluid production of a single well increased from 83m³. 3 Dropped to 69m 3 Daily oil production increased by 5.22 tons, and water content decreased by 7.6 percentage points, with good results from the field test.

[0165] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the implementation methods of the present invention, and should be understood that the scope of protection of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed in this invention without departing from the spirit of the invention, and these modifications and combinations are still within the scope of protection of the present invention.

Claims

1. A method for plugging crossflow in a production well after ternary composite flooding, characterized in that: Includes the following steps: S1: Select the well to be sealed and determine the sealing layer; S2: Based on the well conditions, prepare a temporary plugging agent system, inject the temporary plugging agent into the low-permeability layer, and control the breaking time of the temporary plugging agent; S3: After the temporary plugging agent is injected into the low-permeability layer, the plugging and sealing agent is injected into the high-permeability layer of the well to be sealed. S4: After the sealing and plugging agent is injected, the sealing agent is injected into the well to be sealed. S5: After conducting a test injection of the sealed well, measuring the injection volume of the layer, and testing the production profile, the well is opened for production.

2. The method for plugging crossflow in a production well after ternary composite flooding according to claim 1, characterized in that: Step S1: Selecting the method for sealing out cross-flow wells: In well areas with well-developed river sand, good connectivity, perfect injection-production relationship and a certain pressure space, production wells with successor layers, significant differences in oil saturation or water flooding between layers, dominant seepage channels and serious inefficient and ineffective circulation are preferred.

3. The method for plugging crossflow in a production well after ternary composite flooding according to claim 2, characterized in that: Step S1: Method for determining the sealing layer: Select the layer with an effective thickness of more than 2m, a permeability greater than the average level of the whole area, and a high water flooding layer thickness ratio of less than 60% as the sealing layer.

4. The method for plugging crossflow in a production well after ternary composite flooding according to claim 1, characterized in that: Step S2 temporary plugging agent system includes polymer, crosslinking agent, depolymerizer and stabilizer; The polymer is partially hydrolyzed polyacrylamide; molecular weight 3 million to 25 million, degree of hydrolysis 1% to 18%, concentration: 0.3-0.5%; The crosslinking agent is an organic chromium crosslinking agent, which is either chromium lactate or chromium acetate. The relationship between the amounts of the polymer and the crosslinking agent can be expressed by the crosslinking ratio, which is between 20:1 and 60:

1. The degreasing agent is potassium permanganate or sodium hypochlorite, with a concentration of 0.01-0.02%; The stabilizer is urea at a concentration of 0.02-0.04%.

5. The method for plugging crossflow in a production well after ternary composite flooding according to claim 4, characterized in that: The preparation method of the temporary plugging agent includes the following steps: c1. Dissolve 0.3%-0.5% of partially hydrolyzed polyacrylamide in water at room temperature by stirring. c2. Add the crosslinking agent to the solution obtained in c1 and stir to dissolve; c3. Add 0.01%-0.02% of the decolloid to the solution obtained in c2 and stir to dissolve; c4. Add 0.02%-0.04% of stabilizer to the solution obtained in c3 and stir until completely dissolved to obtain the temporary plugging agent.

6. The method for plugging crossflow in a production well after ternary composite flooding according to claim 1, characterized in that: Step S3 involves injecting the blocking and channeling agent by slowly increasing the injection pressure through variations in injection volume and concentration. Specific methods include: First, inject 1000 mg / L of plugging and channeling agent. If the injection pressure rises rapidly, reduce the concentration of the plugging and channeling agent to 500 mg / L. If the pressure continues to rise, reduce the daily injection volume of the plugging and channeling agent. If the injection pressure rises slowly, increase the concentration of the plugging and channeling agent to 1500–3000 mg / L. The injection pressure is then increased slowly by varying the injection volume and concentration.

7. The method for plugging crossflow in a production well after ternary composite flooding according to claim 6, characterized in that: Rapid pressure rise refers to a pressure increase of more than 1.0 MPa within 5 days; Slow pressure rise refers to a pressure increase of less than 1.0 MPa within 5 days.

8. The method for plugging crossflow in a production well after ternary composite flooding according to claim 1, characterized in that: The method for determining the injection volume of the plugging and channeling agent in step S3 is as follows: The sealing agent is designed to have a sealing radius depth of 10m and a sealing thickness that is half the thickness of the high-water-flooding layer. The dosage of the blocking agent is calculated using the injection volume formula of the blocking agent; The injection volume formula for the blocking and intercepting agent is as follows: Among them: Q 封窜剂 —Injection volume of the blocking and intercepting agent, m 3 ;R 封窜 —The sealing radius is a fixed value of 10m; H 水淹 —Thickness of the high-water-flooded layer, m; φ—Porosity of the sealing layer, %; Substituting the sealing radius of 10m into the formula, the simplified formula for calculating the amount of sealing agent injected is obtained as follows: Q 封窜剂 =50×π×H 水淹 ×φ。 9. A method for plugging crossflow in a production well after ternary composite flooding according to claim 8, characterized in that: Design the daily injection volume of the sealing and blocking agent, and calculate the construction period based on the injection volume and daily injection volume of the sealing and blocking agent; The daily dosage of the blocking and intercepting agent is designed to be 30-70 mg / day. 3 .

10. A method for plugging crossflow in a production well after ternary composite flooding according to claim 8, characterized in that: The blocking and sealing agent is an alkali-resistant multi-component complex gel blocking and sealing agent; The alkali-resistant multi-component complexing gel blocking agent is made of partially hydrolyzed polyacrylamide, organic chromium crosslinking agent, thiourea stabilizer and water; the mass ratio of partially hydrolyzed polyacrylamide, organic chromium crosslinking agent and thiourea stabilizer is 0.05-0.3% : 0.2-0.35% : 0.04-0.08%; The partially hydrolyzed polyacrylamide has a molecular weight of 3 million to 25 million and a degree of hydrolysis of 1% to 18%; the organic chromium crosslinking agent is chromium lactate or chromium acetate.

11. A method for plugging crossflow in a production well after ternary composite flooding according to claim 10, characterized in that: The preparation method of the alkali-resistant multi-component complexed gel blocking and channeling agent includes the following steps: b1. Dissolve 0.05%-0.3% of partially hydrolyzed polyacrylamide in water at room temperature by stirring. b2. Add 0.2-0.35% of organic chromium crosslinking agent to the solution obtained in step b1 and stir to dissolve; b3. Add 0.04%-0.08% of a stabilizer to the solution obtained in step b2 to obtain the temporary plugging agent.

12. The method for plugging crossflow in a production well after ternary composite flooding according to claim 1, characterized in that: Step S4 uses a micro-expansion sealing agent; the micro-expansion sealing agent is composed of the following components by weight percentage: 14%-17% main agent; 0.3%-0.4% crosslinking agent; 0.15%-0.18% reinforcing agent; 4%-9% micro-expansion additive; balance is water; The main agent is a mixture of irradiated acrylamide and bentonite; The micro-expansion additive is OP-10 or sodium dodecylbenzenesulfonate; The crosslinking agent is one or a mixture of sodium persulfate and potassium persulfate; The reinforcing agent is N,N-methylenebisacrylamide.

13. A method for plugging crossflow in a production well after ternary composite flooding according to claim 12, characterized in that: The preparation method of the micro-expansion plugging agent includes the following steps: a1. Dissolve the main agent in 14%-17% water at room temperature by stirring. a2. Add 0.3%-0.4% of crosslinking agent to the solution obtained in step a1 and stir to dissolve; a3. Add 0.15%-0.18% of the reinforcing agent to the solution obtained in step a2 and stir to dissolve; a4. Add 4%-9% of micro-expansion additive to the solution obtained in step a3 and stir until completely dissolved to obtain the micro-expansion plugging agent.

14. The method for plugging crossflow in a production well after ternary composite flooding according to claim 1, characterized in that: Step S4, determining the amount of sealing agent injected, includes the following steps: The sealing agent is designed to have a sealing radius of 2 meters, with a 2-meter oil drainage channel reserved. Calculate the amount of sealing agent to be injected using a formula; The formula for calculating the amount of sealing agent injected is as follows: Among them: Q 封口剂 —The amount of sealing agent injected, m 3 ;R 封口 —The sealing radius of the sealant is a fixed value of 2m; R 泄油 —The radius of the oil drain channel is a fixed value of 2m; H 水淹 —Thickness of the high-water-flooded layer, m; φ—Porosity of the sealing layer, %; R 封口 For fixed values ​​2m and R 泄油 Substituting the fixed value 2m into the formula, we obtain the simplified formula for the sealing agent injection amount: Q 封口剂 =6×π×H 水淹 ×φ。 15. The method for plugging crossflow in a production well after ternary composite flooding according to claim 1, characterized in that: Step S4 involves injecting a sealing agent into the well. During the injection process, the injection rate and pressure are accurately recorded. The well is then shut in under pressure and allowed to solidify for 24 hours.

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