Inorganic gel blocking agent capable of delaying crosslinking as well as preparation method and application of inorganic gel blocking agent

Abstract

The invention provides an inorganic gel blocking agent capable of delaying crosslinking and a preparation method and application thereof.The inorganic gel blocking agent is prepared from, by weight, 0.2-0.4 part of salt-resistant polymer, 0.5-2 parts of silicate and 0.1-0.4 part of complex, and the three materials are selected for matching, so that the crosslinking-delaying inorganic gel blocking agent is prepared. By means of the electrostatic repulsion effect of cations in the salt-resistant polymer and the complexation effect of the complex, the gelation time of the inorganic gel blocking agent is long, when the inorganic gel blocking agent is applied to blocking of deep high-permeability channel oil fields, injected water waves and the volume can be enlarged, the crude oil recovery rate in water flooding is effectively increased, and the inorganic gel blocking agent has important research significance.

Description

Technical Field

[0001] The invention belongs to the technical field of oil field development, and in particular relates to an inorganic gel plugging agent with delayed cross-linking, a preparation method and application thereof. Background Art

[0002] During deep well drilling, the temperature increases with the depth of the formation. As the drilling progresses deeper, the time the drilling fluid stays deep in the formation increases, which places more stringent requirements on the temperature resistance of the drilling fluid treatment agent.

[0003] At present, water flooding is the main development method for oil fields. Factors such as long-term water flooding lead to the formation of large pores with medium and high permeability in underground reservoirs, inefficient and ineffective circulation of injected water, and difficulty in effectively displacing a large amount of underground crude oil. The development and production costs of oil fields are high and the benefits are low. Deep liquid flow diversion and flooding technology is an important means to solve the inefficient and ineffective circulation of water injection in water-driven oilfields and to improve the recovery rate of water-driven development. CN109735314A discloses an organic-inorganic composite silicate high-temperature resistant film-forming drilling fluid system, which is composed of the following raw materials: bentonite-based slurry, a viscosity enhancer, a fluid loss reducer, a plugging agent, a weighting agent, an inorganic silicate and an organic silicate, wherein the amount of each raw material is based on the weight of the bentonite-based slurry, the mass fraction of the bentonite-based slurry is 1-4%, the concentration of the organic silicate is 0.05-0.5 mol / L, and the mass fraction of the inorganic silicate is 0.1-5%. The silicate high-temperature resistant film-forming drilling fluid system provided by the invention improves the ability of drilling fluid to inhibit and prevent collapse, better meets the needs of well wall stability and safe drilling, and achieves the purpose of inhibition, plugging and chemical wall consolidation.

[0004] However, in the inorganic silicate gel plugging system provided in the prior art including the above invention, in highly mineralized reservoirs, especially in reservoirs with high calcium and magnesium ion contents, silicates and divalent metal ions will quickly form precipitation after encountering each other, and the gelation rate is difficult to control, deep liquid flow diversion cannot be achieved, and the water drive development effect is deteriorated.

[0005] Therefore, in order to solve the above technical problems, it is urgent to develop an inorganic gel plugging agent that can effectively delay the gelation time. Summary of the invention

[0006] In view of the deficiencies in the prior art, the object of the present invention is to provide an inorganic gel plugging agent with delayed cross-linking, and a preparation method and application thereof. The inorganic gel plugging agent can effectively delay the gelation time of the inorganic gel plugging agent by selecting a combination of salt-resistant polymers, silicates and complexes, and by virtue of the electrical repulsion of the salt-resistant polymers and the complexation of the complexes, thereby expanding the swept volume of the injected water and effectively improving the crude oil recovery rate, which has important research significance.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides an inorganic gel plugging agent for delayed crosslinking, wherein the inorganic gel plugging agent comprises the following components in parts by weight:

[0009] 0.2-0.4 parts by weight of salt-resistant polymer;

[0010] 0.5-2 parts by weight of silicate;

[0011] Complex 0.1-0.4 parts by weight.

[0012] Wherein, the salt-resistant polymer may be 0.22 parts by weight, 0.24 parts by weight, 0.26 parts by weight, 0.28 parts by weight, 0.3 parts by weight, 0.32 parts by weight, 0.34 parts by weight, 0.36 parts by weight or 0.38 parts by weight, etc.

[0013] The silicate may be in an amount of 0.7 parts by weight, 0.9 parts by weight, 1.1 parts by weight, 1.3 parts by weight, 1.5 parts by weight, 1.7 parts by weight, 1.9 parts by weight, or the like.

[0014] The complex may be 0.15 parts by weight, 0.2 parts by weight, 0.25 parts by weight, 0.3 parts by weight, 0.35 parts by weight, 0.4 parts by weight, etc.

[0015] The inorganic gel plugging agent provided by the present invention comprises specific proportions of salt-resistant polymer, silicate and complex. By selecting the above three materials for combination, with the help of the electrical repulsion between cations and metal ions in the salt-resistant polymer and the complexation of the complex, the obtained inorganic gel plugging agent has a longer gelling time. When it is used for plugging deep hyperpermeable channels, it can expand the injected water wave and volume, improve the crude oil recovery rate in water flooding, and has important research significance.

[0016] Preferably, the raw materials for preparing the salt-resistant polymer include monomers, initiators and deionized water.

[0017] Preferably, the monomer includes any one of acrylamide, acrylic acid, sodium 3-acrylamido-3-methylbutyrate (NaNMB), sodium 2-acrylamido-2-methylpropane sulfonate (AMPS), sodium p-styrene sulfonate (NaVBS), sodium vinyl sulfonate, methacryloyloxyethyltrimethylammonium chloride (DMC), N,N-dimethyldiallylammonium chloride, acryloyloxyethyltrimethylammonium chloride (DAC), dodecyldimethylallylammonium chloride or octadecyldimethylallylammonium bromide, or a combination of at least two thereof.

[0018] Preferably, the monomer includes any one of acrylamide, sodium 3-acrylamido-3-methylbutyrate, sodium p-styrene sulfonate or octadecyl dimethyl allyl ammonium bromide, or a combination of at least two thereof.

[0019] Preferably, the initiator includes any one of ammonium persulfate, potassium persulfate, sodium pyrosulfite, sodium sulfite, ethylenediamine or triethylamine, or a combination of at least two thereof.

[0020] Preferably, the initiator comprises triethylamine, potassium persulfate and sodium metabisulfite.

[0021] Preferably, the silicate includes any one of sodium silicate, lithium silicate, potassium silicate or magnesium aluminum silicate, or a combination of at least two thereof.

[0022] Preferably, the silicate comprises sodium silicate.

[0023] Preferably, the complex comprises any one of disodium ethylenediaminetetraacetate, tetrasodium ethylenediaminetetraacetate, sodium citrate or sodium tartrate, or a combination of at least two thereof.

[0024] Preferably, the complex comprises sodium citrate and / or tetrasodium EDTA.

[0025] Preferably, the inorganic gel plugging agent also includes water.

[0026] Preferably, the water content in the inorganic gel plugging agent is 97.2-99.2 parts by weight, for example, 97.2 parts by weight, 97.4 parts by weight, 97.6 parts by weight, 97.8 parts by weight, 98 parts by weight, 98.2 parts by weight, 98.4 parts by weight, 98.6 parts by weight, 98.8 parts by weight or 99 parts by weight.

[0027] In a second aspect, the present invention provides a method for preparing the inorganic gel plugging agent as described in the first aspect, the preparation method comprising: mixing a salt-resistant polymer, a silicate and a complex in water to obtain the inorganic gel plugging agent.

[0028] In a third aspect, the present invention provides a use of the inorganic gel plugging agent as described in the first aspect in oil field development.

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

[0030] (1) The inorganic gel plugging agent provided by the present invention comprises 0.2-0.4 parts by weight of salt-resistant polymer, 0.5-2 parts by weight of silicate and 0.1-0.4 parts by weight of complex. By selecting the above three materials for combination, it has a longer gelling time. Specifically, based on a concentration of 10×10 4 mg / L simulated saline (Ca 2+=4000mg / L), at 80℃, compared with conventional HPAM polymer plugging agent, it can delay the gelation time of inorganic gel for up to 7h;

[0031] (2) The inorganic gel plugging agent provided by the present invention also has high deep migration and plugging performance. Specifically, based on 10×10 4 mg / L simulated saline (Ca 2+ =4000mg / L), using a sand filling tube with a length of 100cm and a diameter of 2.5cm (divided into three sections, namely the head end L1, the middle part L2 and the end L3), the inorganic gel plugging agent provided by the present invention has shielding and complexing effects, reducing the silicate and Ca 2+ As the inorganic gel plugging agent migrates inside the core, the cationic groups in the salt-resistant polymer in the inorganic gel plugging agent adsorb and retain the negatively charged quartz sand, and the shielding effect of the salt-resistant polymer is weakened, allowing silicate to interact with Ca 2+ Rapid gelation; compared with simulated brine, it can achieve deep migration and plugging, and expand the volume of injected water. The plugging system prepared by simulated brine + silicate is mainly used to plug the L1 section of the sand filling pipe, and only a small part of it is used to plug the L3 section, and the deep migration effect is poor. DETAILED DESCRIPTION

[0032] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0033] Preparation Example 1

[0034] A salt-resistant polymer, the preparation method of which comprises: adding 72.7 parts by weight of deionized water, 20 parts by weight of acrylamide, 3 parts by weight of sodium 3-acrylamido-3-methylbutyrate (NaNMB), 2 parts by weight of sodium p-styrene sulfonate and 2 parts by weight of octadecyl dimethyl allyl ammonium bromide in sequence into a stoppered wide-mouth bottle, introducing nitrogen for 20 minutes, controlling the polymerization temperature to be 15°C, adding 0.3 parts by weight of triethylamine, 0.2 parts by weight of potassium persulfate and 0.1 parts by weight of sodium pyrosulfite, continuing to introduce nitrogen for 10 minutes, carrying out polymerization reaction for 4 hours, granulating the polymerized colloid, drying at 70°C for 4 hours, and passing through a 50-mesh standard sieve to obtain the salt-resistant polymer.

[0035] Preparation Example 2

[0036] A salt-resistant polymer, the preparation method of which comprises: adding 71.6 parts by weight of deionized water, 20 parts by weight of acrylamide, 3 parts by weight of sodium 3-acrylamido-3-methylbutyrate (NaNMB), 3 parts by weight of sodium p-styrene sulfonate and 2 parts by weight of octadecyl dimethyl allyl ammonium bromide in sequence into a stoppered wide-mouth bottle, introducing nitrogen for 20 minutes, controlling the polymerization temperature to be 15°C, adding 0.4 parts by weight of triethylamine, 0.26 parts by weight of potassium persulfate and 0.13 parts by weight of sodium pyrosulfite, continuing to introduce nitrogen for 10 minutes, carrying out polymerization reaction for 4 hours, granulating the polymerized colloid, drying at 70°C for 4 hours, and passing through a 50-mesh standard sieve to obtain the salt-resistant polymer.

[0037] Preparation Example 3

[0038] A salt-resistant polymer, the preparation method of which comprises: adding 89.6 parts by weight of deionized water, 20 parts by weight of acrylamide, 4 parts by weight of sodium 3-acrylamido-3-methylbutyrate (NaNMB), 3 parts by weight of sodium p-styrene sulfonate and 3 parts by weight of octadecyl dimethyl allyl ammonium bromide in a stoppered wide-mouth bottle in sequence, introducing nitrogen for 20 minutes, controlling the polymerization temperature to be 15°C, adding 0.4 parts by weight of triethylamine, 0.26 parts by weight of potassium persulfate and 0.13 parts by weight of sodium pyrosulfite, continuing to introduce nitrogen for 10 minutes, carrying out polymerization reaction for 4 hours, granulating the polymerized colloid, drying at 70°C for 4 hours, and passing through a 60-mesh standard sieve to obtain the salt-resistant polymer.

[0039] Preparation Example 4

[0040] A salt-resistant polymer, the preparation method of which comprises: adding 89.6 parts by weight of deionized water, 20 parts by weight of acrylamide, 4 parts by weight of sodium 3-acrylamido-3-methylbutyrate (NaNMB), 3 parts by weight of sodium p-styrene sulfonate and 2 parts by weight of octadecyl dimethyl allyl ammonium bromide in sequence into a stoppered wide-mouth bottle, introducing nitrogen for 20 minutes, controlling the polymerization temperature to be 15°C, adding 0.5 parts by weight of triethylamine, 0.32 parts by weight of potassium persulfate and 0.16 parts by weight of sodium pyrosulfite, continuing to introduce nitrogen for 10 minutes, carrying out polymerization reaction for 4 hours, granulating the polymerized colloid, drying at 70°C for 4 hours, and passing through a 40-mesh standard sieve to obtain the salt-resistant polymer.

[0041] Example 1

[0042] A delayed cross-linking inorganic gel plugging agent, the preparation method of which comprises: adding 99.2 parts by weight of 10×10 4 mg / L simulated saline (Ca 2+=4000 mg / L), start an electric stirrer, add 0.1 parts by weight of tetrasodium ethylenediaminetetraacetate, 0.2 parts by weight of salt-resistant polymer (Preparation Example 1) and 0.5 parts by weight of sodium silicate in sequence, and stir continuously for 60 min until completely dissolved, pour it into a 100 mL blue-capped reagent bottle, and place it in a water bath at 80° C. to obtain the inorganic gel plugging agent with delayed cross-linking.

[0043] Example 2

[0044] A delayed cross-linking inorganic gel plugging agent, the preparation method of which comprises: adding 98.5 parts by weight of 10×10 4 mg / L simulated saline (Ca 2+ =4000 mg / L), start an electric stirrer, add 0.2 parts by weight of sodium citrate, 0.3 parts by weight of salt-resistant polymer (Preparation Example 2) and 1 part by weight of sodium silicate in sequence, and stir continuously for 60 min until completely dissolved, pour it into a 100 mL blue-capped reagent bottle, and place it in a water bath at 80° C. to obtain the inorganic gel plugging agent with delayed cross-linking.

[0045] Example 3

[0046] A delayed cross-linking inorganic gel plugging agent, the preparation method of which comprises: adding 98.3 parts by weight of 10×10 4 mg / L simulated saline (Ca 2+ =4000 mg / L), start an electric stirrer, add 0.3 parts by weight of sodium citrate, 0.4 parts by weight of salt-resistant polymer (Preparation Example 3) and 1 part by weight of sodium silicate in sequence, and stir continuously for 60 minutes until completely dissolved, pour it into a 100 mL blue-capped reagent bottle, and place it in a water bath at 80° C. to obtain the inorganic gel plugging agent with delayed cross-linking.

[0047] Example 4

[0048] A delayed cross-linking inorganic gel plugging agent, the preparation method of which comprises: adding 97.2 parts by weight of 10×10 4 mg / L simulated saline (Ca 2+ =4000 mg / L), start an electric stirrer, add 0.4 parts by weight of sodium citrate, 0.4 parts by weight of salt-resistant polymer (Preparation Example 4) and 2 parts by weight of sodium silicate in sequence, and stir continuously for 60 minutes until completely dissolved, pour it into a 100 mL blue-capped reagent bottle, and place it in a water bath at 80° C. to obtain the inorganic gel plugging agent with delayed cross-linking.

[0049] Comparative Example 1

[0050] An inorganic gel plugging agent, which differs from Example 1 only in that the added amount of the salt-resistant polymer is 0.5 parts by weight, the added amount of the sodium silicate is 0.2 parts by weight, and the other components, amounts and preparation methods are the same as those in Example 1.

[0051] Comparative Example 2

[0052] An inorganic gel plugging agent, which differs from Example 1 only in that the added amount of the salt-resistant polymer is 0.1 parts by weight, the added amount of the sodium silicate is 0.6 parts by weight, and the other components, amounts and preparation methods are the same as those in Example 1.

[0053] Comparative Example 3

[0054] An inorganic gel plugging agent, which differs from Example 1 only in that HPAM polymer is used to replace the salt-resistant polymer provided in Preparation Example 1, and other components, amounts and preparation methods are the same as those in Example 1.

[0055] Performance Test:

[0056] (1) Delayed gelation performance:

[0057] Under the condition of 80° C., the gelling time of the inorganic gel plugging agents provided in Examples 1 to 4 and Comparative Examples 1 to 3 was tested, and the test results are shown in Table 1:

[0058] Table 1

[0059] Delayed gelation time / h Example 1 4 Example 2 6 Example 3 7 Example 4 6 Comparative Example 1 3 Comparative Example 2 5 Comparative Example 3 3.2

[0060] (2) Deep migration and plugging performance:

[0061] Quartz sand with a mesh size of 60 to 100 was filled into a sand-filled tube with a length of 100 cm and a diameter of 2.5 cm. The sand-filled tube had four pressure measuring points (the two middle pressure measuring points were at the entrance and 30 cm from the end of the sand-filled tube, respectively). Simulated brine was injected into the saturated sand-filled tube at a rate of 0.5 mL / min to measure its permeability before plugging. Then, 1 / 3 PV polymer solution, 1 / 3 PV delayed cross-linking inorganic gel plugging agent, and 1 / 3 PV 1% sodium silicate solution were injected into the sand-filled tube, respectively. Both ends of the core tube were sealed and placed in a drying oven at 80°C for 24 hours. Then, 1 / 3 PV simulated brine displacement was injected at a rate of 0.5 mL / min to investigate the deep migration and plugging performance of the system.

[0062] The inorganic gel plugging agents provided in Examples 1 to 4 and Comparative Examples 1 to 2 were tested according to the above test method. The test results are shown in Table 2:

[0063] Table 2

[0064]

[0065]

[0066] Note: The permeability of L1 section is calculated by the pressure difference between P1 and P2 and the length of L1, the permeability of L2 section is calculated by the pressure difference between P3 and P2 and the length of L2, and the permeability of L3 section is calculated by the pressure difference between P3 and P4 and the length of L3.

[0067] According to the data in Table 1 and Table 2, we can see that:

[0068] First, the inorganic gel plugging agent provided by the present invention has excellent delayed gelation performance. This is because the salt-resistant polymer used therein has a chain hydrophobic group association effect. Compared with conventional HPAM, it has a higher apparent viscosity and greater molecular motion resistance. In addition, the shielding effect of the cationic group on the polymer chain reduces the interaction between silicate and Ca to a certain extent. 2+ The contact opportunity delays the gelation time of the inorganic silicate system, and the complexing agent contained in it has a great influence on Ca 2+ The complexation of the inorganic gel plugging agent also further slows down the gelation rate;

[0069] Secondly, the inorganic gel plugging agent provided by the present invention has excellent deep migration and plugging performance; after the inorganic gel plugging agent and silicate are injected into the sand filling pipe, the shielding effect of the cationic group in the salt-resistant polymer in the inorganic gel plugging agent provided by the present invention and the complexation of the complex reduce the silicate and Ca 2+ As the salt-resistant polymer migrates inside the core, the cationic groups of the polymer and the negatively charged quartz sand undergo adsorption and retention, the shielding effect of the salt-resistant polymer is weakened, and the silicate and Ca 2+ The inorganic gel plugging agent provided by the present invention has high plugging performance in both L2 and L3 sections, while the comparative example is relatively weak, showing poor deep migration and plugging performance;

[0070] Finally, by comparing the data of Example 1 and Comparative Examples 1 to 3, it can be seen that the amount of salt-resistant polymer added in the inorganic gel plugging agent is relatively high (Comparative Example 1). Although the gelation delay performance is improved, the plugging performance is deteriorated due to the low amount of silicate added; the amount of salt-resistant polymer added in the inorganic gel plugging agent is relatively low (Comparative Example 2), which will lead to the deterioration of the gelation delay performance; and the plugging agent prepared by the HPAM polymer provided in Comparative Example 3 has poor gelation delay performance and plugging performance.

[0071] The applicant declares that the present invention uses the above-mentioned embodiments to illustrate an inorganic gel plugging agent that can effectively delay the gelation time and its preparation method and application, but the present invention is not limited to the above-mentioned embodiments, that is, it does not mean that the present invention must rely on the above-mentioned embodiments to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A delayed cross-linking inorganic gel plugging agent, characterized in that: The inorganic gel plugging agent comprises the following components in parts by weight: 0.2-0.4 parts by weight of salt-resistant polymer; 0.5-2 parts by weight of silicate; Complex 0.1-0.4 parts by weight.

2. The inorganic gel plugging agent according to claim 1, characterized in that: The raw materials for preparing the salt-resistant polymer include monomers, initiators and deionized water.

3. The inorganic gel plugging agent according to claim 2, characterized in that: The monomers include any one of acrylamide, acrylic acid, sodium 3-acrylamido-3-methylbutyrate, sodium 2-acrylamido-2-methylpropanesulfonate, sodium p-styrenesulfonate, sodium vinylsulfonate, methacryloyloxyethyl trimethylammonium chloride, N,N-dimethyldiallylammonium chloride, acryloyloxyethyl trimethylammonium chloride, dodecyl dimethylallylammonium chloride or octadecyl dimethylallylammonium bromide, or a combination of at least two thereof; Preferably, the monomer includes any one of acrylamide, sodium 3-acrylamido-3-methylbutyrate, sodium p-styrene sulfonate or octadecyl dimethyl allyl ammonium bromide, or a combination of at least two thereof.

4. The inorganic gel plugging agent according to claim 2 or 3, characterized in that: The initiator includes any one of ammonium persulfate, potassium persulfate, sodium pyrosulfite, sodium sulfite, ethylenediamine or triethylamine, or a combination of at least two thereof; Preferably, the initiator comprises a combination of triethylamine, potassium persulfate and sodium metabisulfite.

5. The inorganic gel plugging agent according to any one of claims 1 to 4, characterized in that: The silicate includes any one of sodium silicate, lithium silicate, potassium silicate or magnesium aluminum silicate or a combination of at least two thereof; Preferably, the silicate comprises sodium silicate.

6. The inorganic gel plugging agent according to any one of claims 1 to 5, characterized in that: The complex comprises any one or a combination of at least two of disodium ethylenediaminetetraacetate, tetrasodium ethylenediaminetetraacetate, sodium citrate or sodium tartrate; Preferably, the complex comprises sodium citrate and / or tetrasodium EDTA.

7. The inorganic gel plugging agent according to any one of claims 1 to 6, characterized in that: The inorganic gel plugging agent also includes water.

8. The inorganic gel plugging agent according to claim 7, characterized in that: The water content in the inorganic gel plugging agent is 97.2 to 99.2 parts by weight.

9. A method for preparing the inorganic gel plugging agent according to any one of claims 1 to 8, characterized in that: The preparation method comprises: mixing a salt-resistant polymer, a silicate and a complex in water to obtain the inorganic gel plugging agent.

10. Use of the inorganic gel plugging agent according to any one of claims 1 to 8 in oil field development.

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