In-situ degradation temporary plugging composition and application thereof, reagent composition for shaft plugging and shaft plugging method

Abstract

The invention belongs to the technical field of oilfield chemistry, and particularly relates to an in-situ degradation temporary plugging composition and application thereof, a reagent composition for shaft plugging and a shaft plugging method. The in-situ degradation temporary plugging composition comprises a temporary plugging solution and an initiator solution, the temporary plugging liquid is prepared from the following components in percentage by mass: 7 to 12 percent of acrylamide, 1 to 4 percent of acrylic acid, 0.2 to 0.5 percent of cross-linking agent, 0.002 to 0.005 percent of gelatinizing agent, 0.02 to 0.05 percent of gel breaker and the balance of water. The gelatinizing agent comprises one or more of ferric sulfate, ferrous sulfate, copper sulfate and zinc sulfate; the gel breaker comprises one or more of sodium propoxide, polyethyleneimine and ethylenediamine. Acrylamide, acrylic acid and a cross-linking agent are subjected to free radical polymerization reaction at 2-20 DEG C under the action of a gelatinizing agent to form gel of a three-dimensional network structure, and gelatinizing at low temperature is realized; then, under the action of a gel breaker, the three-dimensional network structure collapses, gel is gradually broken, and in-situ degradation at the low temperature is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of oilfield chemistry, and in particular relates to an in-situ degradation temporary plugging composition and application thereof, a reagent composition for wellbore plugging and a wellbore plugging method. Background Art

[0002] With the continuous development of offshore oil fields, the number of oil and gas wells entering the middle and late stages of development has gradually increased, and production facilities are seriously aging, requiring well repair tasks such as damaged pipe repair and troubleshooting. Before well repair, for the sake of well control safety, the target well section is often temporarily plugged first. Gel temporary plugging agents have the advantages of controllable gelation time and degradation time, and high gel strength, and are often used for temporary plugging of wellbores. However, the gelation temperature of existing gel temporary plugging agents is generally high (above 25°C), and it is difficult to achieve gelation at low temperatures (2-20°C) and degradation at low temperatures, which limits their application. Summary of the invention

[0003] In view of this, the purpose of the present invention is to provide an in-situ degradable temporary plugging composition and its application, a reagent composition for wellbore plugging and a wellbore plugging method. The in-situ degradable temporary plugging composition of the present invention can gel and degrade at low temperature.

[0004] The present invention provides an in-situ degradation temporary plugging composition, comprising a packaged temporary plugging liquid and an initiator solution;

[0005] The temporary plugging fluid comprises the following components in percentage by mass: 7-12% acrylamide, 1-4% acrylic acid, 0.2-0.5% cross-linking agent, 0.002-0.005% gelling agent, 0.02-0.05% gelling agent, and the balance water;

[0006] The gelling agent includes one or more of ferric sulfate, ferrous sulfate, copper sulfate and zinc sulfate;

[0007] The debonding agent includes one or more of sodium propoxide, polyethyleneimine and ethylenediamine;

[0008] The initiator solution comprises the following components in mass percentage: 0.04-0.1% initiator and the balance water.

[0009] Preferably, the mass percentage of the gelling agent in the temporary plugging fluid is 0.003-0.004%.

[0010] Preferably, the mass percentage of the breaker in the temporary plugging fluid is 0.03-0.04%.

[0011] Preferably, the cross-linking agent is polyethylene glycol diacrylate.

[0012] Preferably, the temporary plugging fluid comprises the following components in percentage by mass:

[0013] Acrylamide 7%, acrylic acid 3%, polyethylene glycol diacrylate 0.5%, ferrous sulfate 0.002-0.005%, ethylenediamine 0.02-0.05%, balance water;

[0014] Or including the following components in mass percentage:

[0015] Acrylamide 8%, acrylic acid 2%, polyethylene glycol diacrylate 0.5%, ferrous sulfate 0.004%, ethylenediamine 0.03%, and the balance water.

[0016] Preferably, the mass ratio of the temporary plugging liquid to the initiator solution is 1 to 3:1.

[0017] The present invention also provides the use of the in-situ degradable temporary plugging composition described in the above technical solution in wellbore plugging.

[0018] The present invention also provides a reagent composition for wellbore plugging, comprising a pre-fluid, a temporary plugging fluid, an isolation fluid and an initiator solution in separate packages;

[0019] The pre-fluid comprises the following components in percentage by mass: 0.1-0.4% acrylamide polymer, 1-10% weighting agent, and the balance water;

[0020] The temporary plugging liquid is the temporary plugging liquid in the in-situ degradation temporary plugging composition described in the above technical solution;

[0021] The isolation liquid comprises the following raw materials in percentage by mass: 0.4-0.8% thixotropic polymer, 0.1-0.6% surfactant, and the balance water; the thixotropic polymer is sodium polyacrylate;

[0022] The initiator solution is the initiator solution in the in-situ degradation temporary plugging composition described in the above technical solution.

[0023] Preferably, the mass ratio of the pre-fluid, temporary plugging liquid, spacer liquid and initiator solution is 1:2:2:1 to 1:2:4:1.

[0024] The present invention also provides a method for plugging a wellbore using the reagent composition for plugging a wellbore according to the above technical solution, comprising the following steps:

[0025] S1: injection of pre-fluid;

[0026] S2: inject temporary plugging fluid;

[0027] S3: inject isolation fluid;

[0028] S4: Inject the initiator solution.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The invention provides an in-situ degradation temporary plugging composition, comprising a temporary plugging liquid and an initiator solution which are packaged separately; the temporary plugging liquid comprises the following components in mass percentage: 7-12% acrylamide, 1-4% acrylic acid, 0.2-0.5% crosslinking agent, 0.002-0.005% gelling agent, 0.02-0.05% gelling agent, and the balance is water; the gelling agent comprises one or more of ferric sulfate, ferrous sulfate, copper sulfate and zinc sulfate; the gelling agent comprises one or more of sodium propoxide, polyethyleneimine and ethylenediamine; the initiator solution comprises the following components in mass percentage: 0.04-0.1% initiator, and the balance is water.

[0031] The in-situ degradation temporary plugging composition of the present invention comprises acrylamide monomer, acrylic acid functional monomer, crosslinking agent, gelling agent and gelling agent. The gelling agent of the present invention can reduce the activation energy of chemical reaction. Under the action of the gelling agent, a three-dimensional network structure gel can be formed by free radical polymerization at a temperature of 2 to 20°C, thereby achieving gelling at low temperature, and solving the problem that the existing gel temporary plugging agent is difficult to gel at a low temperature of 2 to 20°C. Afterwards, under the action of the gelling agent, the ester group breaks, the three-dimensional network structure collapses, the temporary plugging gel breaks, and low-temperature in-situ degradation is achieved.

[0032] Furthermore, the present invention achieves controllable gelling time by adjusting the dosage of gelling agent, and the gelling time is shortened by increasing the dosage of gelling agent; and the gelling time is controllable by adjusting the dosage of gelling agent, and the gelling time is shortened by increasing the dosage of gelling agent.

[0033] The present invention also provides a method for plugging a wellbore, which uses a "four-stage" injection process method to sequentially inject a pre-liquid, a temporary plugging liquid, an isolation liquid, and an initiator solution, and adjusts the amount of injected liquid to adjust the length of the liquid column, thereby adjusting the contact time between the temporary plugging liquid and the initiator solution, thereby achieving controllable gelation time; at the same time, it avoids the problem of gelation at room temperature on the ground during the liquid preparation process, or gelation before the pump reaches the specified position in the wellbore. DETAILED DESCRIPTION

[0034] The present invention provides an in-situ degradation temporary plugging composition, comprising a packaged temporary plugging liquid and an initiator solution;

[0035] The temporary plugging fluid comprises the following components in percentage by mass: 7-12% acrylamide, 1-4% acrylic acid, 0.2-0.5% cross-linking agent, 0.002-0.005% gelling agent, 0.02-0.05% gelling agent, and the balance water;

[0036] The gelling agent includes one or more of ferric sulfate, ferrous sulfate, copper sulfate and zinc sulfate;

[0037] The debonding agent includes one or more of sodium propoxide, polyethyleneimine and ethylenediamine;

[0038] The initiator solution comprises the following components in mass percentage: 0.04-0.1% initiator and the balance water.

[0039] In the present invention, unless otherwise specified, the materials and equipment used are commercially available products in the art.

[0040] In the present invention, the mass percentage of acrylamide in the temporary plugging liquid is preferably 8-10%; the acrylamide, as a reaction monomer, has a relatively low viscosity, and low-viscosity injection can be achieved during plugging.

[0041] In the present invention, the mass percentage of acrylic acid in the temporary plugging fluid is preferably 2-3%; the acrylic acid is a functional monomer, and the carboxyl group in the acrylic acid can enhance the adhesion between the gel and the inner wall of the wellbore and improve the plugging strength.

[0042] In the present invention, the crosslinking agent is preferably polyethylene glycol diacrylate. The crosslinking agent of the present invention forms covalent bonds with acrylamide and acrylic acid monomers, and is more conducive to gelling at low temperature (2-20°C) under the action of a gelling agent compared with crosslinking agents that form ionic bonds such as chromium acetate.

[0043] In the present invention, the mass percentage of polyethylene glycol diacrylate in the temporary plugging fluid is preferably 0.3-0.4%, and the weight average molecular weight of the polyethylene glycol diacrylate is preferably 10,000.

[0044] In the present invention, the gelling agent is preferably ferrous sulfate, and the mass percentage of the gelling agent in the temporary plugging liquid is preferably 0.003-0.004%. The gelling agent of the present invention can reduce the reaction activation energy and achieve gelling at low temperature (2-20°C).

[0045] In the present invention, the breaker is preferably ethylenediamine; the mass percentage of the breaker in the temporary plugging liquid is preferably 0.03-0.04%. The breaker of the present invention can break the ester group of the gel at low temperature and can achieve in-situ gel breaking at low temperature (2-20°C).

[0046] In the present invention, the temporary plugging fluid preferably includes the following components in mass percentage:

[0047] Acrylamide 7%, acrylic acid 3%, polyethylene glycol diacrylate 0.5%, ferrous sulfate 0.002-0.005%, ethylenediamine 0.02-0.05%, balance water;

[0048] Or including the following components in mass percentage:

[0049] Acrylamide 8%, acrylic acid 2%, polyethylene glycol diacrylate 0.5%, ferrous sulfate 0.004%, ethylenediamine 0.03%, and the balance water.

[0050] In the present invention, the initiator in the initiator solution preferably includes one or more of ammonium persulfate, potassium persulfate, sodium persulfate and sodium bisulfite, and more preferably ammonium persulfate.

[0051] In the present invention, the mass percentage of the initiator in the initiator solution is preferably 0.05-0.08%.

[0052] In the present invention, the mass ratio of the temporary plugging liquid to the initiator solution is preferably 1 to 3:1, more preferably 2:1.

[0053] In the present invention, the temporary plugging liquid and the initiator solution in the in-situ degradable temporary plugging composition are mixed for polymerization reaction to obtain an in-situ degradable temporary plugging gel. The polymerization reaction temperature is preferably 2 to 20° C., more preferably 5 to 15° C., and the time is preferably 3 to 12 hours, more preferably 4 to 6 hours.

[0054] The in-situ degradable temporary plugging gel of the present invention has a low gelling temperature and a controllable gelling time. The gelling agent in the in-situ degradable temporary plugging composition of the present invention acts faster, while the gelling agent acts slower. After gelling, the gelling agent is contained inside the gel. At low temperatures, the gelling agent begins to attack the ester group, causing the ester group to break, thereby achieving gel breaking.

[0055] The present invention also provides the use of the in-situ degradable temporary plugging composition described in the above technical solution in wellbore plugging.

[0056] The present invention also provides a reagent composition for wellbore plugging, comprising a pre-fluid, a temporary plugging fluid, an isolation fluid and an initiator solution in separate packages;

[0057] The pre-fluid comprises the following components in percentage by mass: 0.1-0.4% acrylamide polymer, 1-10% weighting agent, and the balance water;

[0058] The temporary plugging liquid is the temporary plugging liquid in the in-situ degradation temporary plugging composition described in the above technical solution;

[0059] The isolation liquid comprises the following raw materials in percentage by mass: 0.4-0.8% thixotropic polymer, 0.1-0.6% surfactant, and the balance water; the thixotropic polymer is sodium polyacrylate;

[0060] The initiator solution is the initiator solution in the in-situ degradation temporary plugging composition described in the above technical solution.

[0061] In the present invention, the mass ratio of the pre-fluid, temporary plugging liquid, cleaning spacer liquid and initiator solution is preferably 1:2:2:1 to 1:2:4:1, more preferably 1:2:3:1.

[0062] In the present invention, the acrylamide polymer is preferably polyacrylamide, and the weight average molecular weight of the polyacrylamide is 5 to 8 million; the weighting agent preferably includes one or more of calcium chloride, potassium chloride and magnesium chloride.

[0063] In the present invention, the pre-fluid preferably comprises the following raw materials in percentage by mass: 0.2% polyacrylamide, 5% calcium chloride, and the balance water.

[0064] In the present invention, the surfactant preferably includes one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, polyoxyethylene dodecylphenol ether (OP-10), polysorbate 80 (Tween 80) and Span 80.

[0065] In the present invention, the isolation liquid preferably comprises the following raw materials in percentage by mass: 0.5% sodium polyacrylate, 0.4% sodium dodecyl sulfate, and the balance water.

[0066] The present invention also provides a method for plugging a wellbore using the reagent composition for plugging a wellbore as described in the above technical solution, comprising the following steps:

[0067] S1: injection of pre-fluid;

[0068] S2: inject temporary plugging fluid;

[0069] S3: inject isolation fluid;

[0070] S4: Inject the initiator solution.

[0071] The present invention first injects a pre-fluid to clean the wellbore.

[0072] The present invention injects an isolation fluid to separate the temporary plugging fluid and the initiator solution to control the gelling time. Through mass transfer, the initiator solution infiltrates into the temporary plugging fluid to initiate a polymerization reaction, thereby forming a plugging layer and plugging the wellbore.

[0073] In the present invention, the reservoir temperature in the wellbore is preferably 2 to 20° C., more preferably 15 to 20° C., the gelling time is preferably 3 to 12 hours, and the degradation time is preferably 2 to 7 days.

[0074] The low-temperature in-situ degradable temporary plugging gel provided by the present invention gels at a temperature of 2 to 20° C., has low viscosity before gelling, is easy to pump into the wellbore, and has controllable gelling time and degradation time. In addition, the method for wellbore plugging provided by the present invention can avoid the problems of gelling at room temperature and gelling during the pumping process.

[0075] To further illustrate the present invention, the in-situ degradation temporary plugging composition and its application, the reagent composition for wellbore plugging and the wellbore plugging method provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be understood as limiting the scope of protection of the present invention.

[0076] Example 1

[0077] In terms of mass percentage, 7% acrylamide, 3% acrylic acid, 0.5% cross-linking agent (polyethylene glycol diacrylate), different mass percentages (0, 0.002%, 0.003%, 0.004%, 0.005%) of low-temperature gelling agent (ferrous sulfate), and 0.04% directional gelling agent (ethylenediamine) were weighed and added into distilled water to prepare 100g temporary plugging liquid;

[0078] In terms of mass percentage, 0.06% initiator (ammonium persulfate) was weighed and added to distilled water to prepare 100 g initiator solution;

[0079] The temporary plugging liquid and the initiator solution were mixed in a mass ratio of 2:1 and placed at 15°C to form a gel. After a period of time, a low-temperature in-situ degradation temporary plugging gel was obtained.

[0080] The gelation time and degradation time of the low-temperature in-situ degradation temporary plugging gel were tested by the bottle test method. The prepared low-temperature in-situ degradation temporary plugging gel reaction solution was placed in a blue-capped bottle, and the blue-capped bottle was inverted at regular intervals. The time when the reaction solution loses its ability to flow was defined as the gelation time; the time required for the gel to flow again after solidification was defined as the degradation time. The effects of different low-temperature gelling agent concentrations on the performance of the low-temperature in-situ degradation temporary plugging gel are shown in Table 1:

[0081] Table 1 Effect of different low-temperature gelling agent concentrations on the performance of low-temperature in-situ degradation temporary plugging gel

[0082]

[0083] It can be seen from Table 1 that with the increase of the concentration of the low-temperature gelling agent, the gelling time of the temporary plugging gel is shortened and the degradation time remains almost unchanged. By changing the concentration of the low-temperature gelling agent, the gelling time can be controlled within a certain range.

[0084] Example 2

[0085] In terms of mass percentage, 7% acrylamide, 3% acrylic acid, 0.5% cross-linking agent (polyethylene glycol diacrylate), 0.004% low-temperature gelling agent (ferrous sulfate), and different mass percentages (0, 0.02%, 0.03%, 0.04%, 0.05%) of directional gel breaker (ethylenediamine) were weighed in sequence and added into distilled water to prepare 100g temporary plugging liquid;

[0086] In terms of mass percentage, 0.05% initiator (ammonium persulfate) was weighed and added to distilled water to prepare 100 g initiator solution;

[0087] The temporary plugging liquid and the initiator solution were mixed in a mass ratio of 2:1 and placed at 15°C to form a gel. After a period of time, a low-temperature in-situ degradation temporary plugging gel was obtained.

[0088] The effects of different directional breaker concentrations on the performance of low-temperature in-situ degradation temporary plugging gel are shown in Table 2:

[0089] Table 2 Effect of different directional breaker concentrations on the performance of low-temperature in-situ degradation temporary plugging gel

[0090]

[0091] It can be seen from Table 2 that with the increase of directional breaker concentration, the degradation time is shortened and the effect on the gelation time is small. By changing the directional breaker concentration, the degradation time can be controlled within a certain range.

[0092] Example 3

[0093] In terms of mass percentage, the pre-fluid (composed of 0.2% polyacrylamide and 5% calcium chloride), temporary plugging liquid (composed of 8% acrylamide, 2% acrylic acid, 0.5% polyethylene glycol diacrylate, 0.004% ferrous sulfate, 0.03% ethylenediamine), cleaning isolation liquid (composed of 0.5% sodium polyacrylate and 0.4% sodium dodecyl sulfate), and initiator solution (0.1% ammonium persulfate solution) were prepared respectively.

[0094] Add pre-liquid, temporary plugging liquid, cleaning isolation liquid and initiator solution to a 500mL blue-cap bottle in sequence, with the mass ratios set to 1:2:2:1, 1:2:3:1 and 1:2:4:1 respectively. React at 15°C and observe the gelation time.

[0095] When the mass ratios of prefill solution, temporary plugging solution, cleaning isolation solution and initiator solution are 1:2:2:1, 1:2:3:1 and 1:2:4:1, the gelling time of the three groups are 3.2h, 7.5h and 11h respectively, and the gelling strength is H measured by the gel code method.

[0096] Although the above-mentioned embodiments have made a detailed description of the present invention, they are only some embodiments of the present invention, rather than all embodiments. People can also obtain other embodiments based on the embodiments of the present invention without creative work, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. An in-situ degradation temporary plugging composition, characterized in that: Including packaged temporary plugging liquid and initiator solution; The temporary plugging fluid comprises the following components in percentage by mass: 7-12% acrylamide, 1-4% acrylic acid, 0.2-0.5% cross-linking agent, 0.002-0.005% gelling agent, 0.02-0.05% gelling agent, and the balance water; The gelling agent includes one or more of ferric sulfate, ferrous sulfate, copper sulfate and zinc sulfate; The debonding agent includes one or more of sodium propoxide, polyethyleneimine and ethylenediamine; The initiator solution comprises the following components in mass percentage: 0.04-0.1% initiator and the balance water.

2. The in-situ degradation temporary plugging composition according to claim 1, characterized in that: The mass percentage of the gelling agent in the temporary plugging fluid is 0.003-0.004%.

3. The in-situ degradation temporary plugging composition according to claim 1, characterized in that: The mass percentage of the gel breaker in the temporary plugging fluid is 0.03-0.04%.

4. The in-situ degradation temporary plugging composition according to claim 1, characterized in that: The cross-linking agent is polyethylene glycol diacrylate.

5. The in-situ degradation temporary plugging composition according to claim 1, characterized in that: The temporary plugging fluid includes the following components in percentage by mass: Acrylamide 7%, acrylic acid 3%, polyethylene glycol diacrylate 0.5%, ferrous sulfate 0.002-0.005%, ethylenediamine 0.02-0.05%, balance water; Or including the following components in mass percentage: Acrylamide 8%, acrylic acid 2%, polyethylene glycol diacrylate 0.5%, ferrous sulfate 0.004%, ethylenediamine 0.03%, and the balance water.

6. The in-situ degradation temporary plugging composition according to claim 1, characterized in that: The mass ratio of the temporary plugging liquid to the initiator solution is 1 to 3:

1.

7. Use of the in-situ degradable temporary plugging composition according to any one of claims 1 to 6 in wellbore plugging.

8. A reagent composition for wellbore plugging, characterized in that: Including pre-filled solution, temporary plugging solution, isolation solution and initiator solution; The pre-fluid comprises the following components in percentage by mass: 0.1-0.4% acrylamide polymer, 1-10% weighting agent, and the balance water; The temporary plugging liquid is the temporary plugging liquid in the in-situ degradation temporary plugging composition according to any one of claims 1 to 6; The isolation liquid comprises the following raw materials in percentage by mass: 0.4-0.8% thixotropic polymer, 0.1-0.6% surfactant, and the balance water; the thixotropic polymer is sodium polyacrylate; The initiator solution is the initiator solution in the in-situ degradation temporary plugging composition according to any one of claims 1 to 6.

9. The reagent composition according to claim 8, characterized in that The mass ratio of the pre-fluid, temporary plugging liquid, isolation liquid and initiator solution is 1:2:2:1 to 1:2:4:

1.

10. A method for plugging a wellbore using the reagent composition for plugging a wellbore according to claim 8 or 9, characterized in that: The following steps are involved: S1: injection of pre-fluid; S2: inject temporary plugging fluid; S3: inject isolation fluid; S4: Inject the initiator solution.

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