Interface reinforcing agent for improving cementing quality of well cementation two interfaces, interface modification prepad fluid and preparation method of interface reinforcing agent and interface modification prepad fluid

Abstract

The invention relates to the technical field of interface reinforcing agent preparation, in particular to an interface reinforcing agent for improving the cementing quality of a well cementation two-interface, a preparation method of the interface reinforcing agent, an interface modification prepad fluid and a preparation method of the interface modification prepad fluid. The raw materials comprise styrene, acrylic acid, acrylonitrile, acrylamide, acrylic acid-2-hydroxyethyl ester, an initiator, styrene, butadiene, an initiator, calcium oxide and deionized water. The interface reinforcing agent for improving the cementing quality of the well cementation two-interface is good in compatibility with drilling fluid, and interface modified prepad fluid obtained by taking the interface reinforcing agent for improving the cementing quality of the well cementation two-interface as a raw material has good suspension stability and filtration loss control capability; the cementing strength of a well cementation interface can be effectively improved, and the cementing quality of the well cementation interface is remarkably improved, so that the purpose of preventing annulus channeling or annulus pressure is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of interface enhancer preparation, and is an interface enhancer for improving the bonding quality of cementing interfaces and a preparation method thereof, and also comprises an interface modified pre-fluid and a preparation method thereof. Background Art

[0002] As far as oil and gas fields are concerned, achieving their expected production capacity and implementing stratified exploitation both depend on the degree of interlayer isolation of the second cementing interface. If the cementing quality of the second interface is poor, it will directly affect the recovery rate and the service life of the oil and gas wells, and cause interlayer crossflow problems after production, which will have an adverse impact on the development of the oil and gas fields.

[0003] The factors that affect the bonding quality of the cementing interface are mainly formation factors, wellbore factors, drilling fluid properties, cement slurry properties, and interface contamination. Among them, the drilling fluid will form a layer of unsolidified mud cake on the well wall, which hinders the direct contact between the cementing fluid and the well wall. The existence of these cementing interface mud cakes is indispensable for drilling construction and is necessary for reducing filtration, maintaining well wall stability and protecting oil and gas reservoirs; on the other hand, the mixing of unclean drilling fluid into the cementing fluid leads to a decrease in the strength of cementing cement. Practice has proved that drilling fluid with good performance not only helps to improve the quality of the wellbore, but also forms a thin and tough mud cake on the well wall, thereby ensuring the quality of cementing. However, the thicker loose mud cake will prevent the cement slurry from directly contacting the well wall, making it difficult to form an effective bonding whole with the cement sheath after cementing, and dehydrated and powdered during the cement hydration process, and easily corroded and damaged by formation water and fracturing fluid to form microcracks, forming channels for oil, gas and water to channel, reducing the bonding quality and sealing performance of the cement sheath interface.

[0004] A Chinese patent document with publication number CN201610749332.9 discloses a carboxylated styrene butadiene latex for cement. By adding carboxylated styrene butadiene latex to cement and utilizing the high-efficiency film strength and bonding properties of carboxylated styrene butadiene latex, the bonding strength, wear resistance, compressive strength, mechanical and chemical stability of the cement are greatly enhanced. However, due to the high amount of styrene added, the latex cures slowly at room temperature to form a film, has a higher hardness, and has reduced flexibility. Summary of the invention

[0005] The present invention provides an interface enhancer, an interface modified pre-fluid and a preparation method thereof for improving the bonding quality of cementing interfaces, which overcome the deficiencies of the above-mentioned prior art and can effectively solve the problems of the existing interface enhancers, such as slow film curing at room temperature, high hardness and reduced flexibility.

[0006] One of the technical solutions of the present invention is achieved through the following measures: an interface enhancer for improving the bonding quality of the second interface of cementing, the raw materials comprising, by weight, 8450 to 9050 parts of styrene, 45 to 55 parts of acrylic acid, 2.0 to 2.5 parts of acrylonitrile, 2.0 to 2.5 parts of acrylamide, 0.5 to 1 part of 2-hydroxyethyl acrylate, 150 to 200 parts of initiator, 8000 to 8500 parts of styrene, 5000 to 5500 parts of butadiene, 300 to 400 parts of initiator, 25 to 30 parts of calcium oxide and 7000 to 11000 parts of deionized water.

[0007] The following is a further optimization and / or improvement of one of the above-mentioned technical solutions: The initiator concentration is 20wt% to 25wt% of the ammonium persulfate aqueous solution.

[0008] The above-mentioned interface enhancer for improving the bonding quality of the cementing interface is obtained by the following method: S1, adding the required amount of acrylic acid, acrylonitrile, acrylamide, 2-hydroxyethyl acrylate, a portion of styrene and a portion of deionized water into a reactor and mixing them evenly, evacuating the reactor and heating it once; S2, adding a portion of initiator to the reactor to cause a polymerization reaction; S3, add the required amount of butadiene, the remaining amount of styrene, the remaining amount of initiator and the remaining amount of deionized water into the reactor and mix them evenly, heat the reactor for a second time, and keep the temperature; S4, adding a required amount of calcium oxide to the reactor, stirring, and then cooling; S5, adjusting the pH value of the reaction product in the reaction kettle, filtering, and obtaining an interface enhancer for improving the bonding quality of the cementing interface.

[0009] In the above step S1, the temperature is 60°C to 70°C during the first heating.

[0010] In the above step S2, the reaction time is 1.0 h to 1.5 h.

[0011] In the above step S3, during the second heating, the temperature is 95° C. to 100° C., and the insulation time is 2.0 h to 2.5 h.

[0012] In the above step S5, the pH value of the reaction product in the reactor is adjusted to 7 to 9.

[0013] The second technical solution of the present invention is achieved by the following measures: A method for preparing an interface enhancer for improving the bonding quality of the cementing interface is carried out as follows: S1, adding the required amount of acrylic acid, acrylonitrile, acrylamide, 2-hydroxyethyl acrylate, a portion of styrene and a portion of deionized water into a reactor and mixing them evenly, evacuating the reactor and heating it once; S2, adding a portion of initiator to the reactor to cause a polymerization reaction; S3, adding a required amount of butadiene, a remaining amount of styrene, a remaining amount of initiator and a remaining amount of deionized water into the reactor and mixing them evenly, heating the reactor for a second time and keeping the temperature; S4, adding a required amount of calcium oxide to the reactor, stirring, and then cooling; S5, adjusting the pH value of the reaction product in the reaction kettle, filtering, and obtaining an interface enhancer for improving the bonding quality of the cementing interface.

[0014] The third technical solution of the present invention is achieved by the following measures: an interface modified pre-fluid prepared with one of the technical solutions as raw materials, the raw materials including 15 parts by weight of an interface enhancer for improving the bonding quality of the second interface of cementing, 0.4 to 0.8 parts of a suspending agent, 45 to 252 parts of a weighting agent and 100 parts of water, obtained by the following method: the interface modified pre-fluid is obtained by sequentially adding the required amount of an interface enhancer, a suspending agent and a weighting agent for improving the bonding quality of the second interface of cementing to the required amount of water and mixing them.

[0015] The following is a further optimization and / or improvement of the third technical solution of the above invention: The above-mentioned suspending agent is one or more of biopolysaccharide, cellulose derivative, clay, bentonite, microsilica powder, vinyl gum, polyvinyl alcohol and inorganic salt.

[0016] The weighting agent is one or more of quartz sand, barite, iron ore powder and iron oxide.

[0017] The fourth technical solution of the present invention is achieved through the following measures: a method for preparing an interface modified pre-fluid is carried out as follows: a required amount of an interface enhancer, a suspending agent, and a weighting agent for improving the bonding quality of the cementing interface are sequentially added to a required amount of water, and the interface modified pre-fluid is obtained after mixing.

[0018] The fifth technical solution of the present invention is achieved through the following measures: a method for using an interface modified pre-fluid, wherein the interface modified pre-fluid is mixed with a water-based drilling fluid and an oil-based drilling fluid in a volume ratio of 3:1 to 1:3 and then used.

[0019] The interface enhancer for improving the bonding quality of the second cementing interface of the present invention has good compatibility with the drilling fluid. The interface modified prefluid obtained by using the interface enhancer for improving the bonding quality of the second cementing interface of the present invention as a raw material has good suspension stability and filtration control ability, can effectively improve the bonding strength of the second cementing interface, and significantly improves the bonding quality of the second cementing interface, thereby achieving the purpose of preventing annular air channeling or annular pressure. DETAILED DESCRIPTION

[0020] The present invention is not limited by the following embodiments, and the specific implementation method can be determined according to the technical scheme of the present invention and the actual situation. Unless otherwise specified, the various chemical reagents and chemicals mentioned in the present invention are all chemical reagents and chemicals known and used in the prior art; unless otherwise specified, the percentages in the present invention are all mass percentages; unless otherwise specified, the solutions in the present invention are all aqueous solutions with water as the solvent, for example, hydrochloric acid solution is a hydrochloric acid aqueous solution; the normal temperature and room temperature in the present invention generally refer to a temperature of 15°C to 25°C, and are generally defined as 25°C.

[0021] The present invention will be further described below in conjunction with embodiments: Embodiment 1: The interface enhancer for improving the bonding quality of the cementing interface comprises, by weight, 8450 to 9050 parts of styrene, 45 to 55 parts of acrylic acid, 2.0 to 2.5 parts of acrylonitrile, 2.0 to 2.5 parts of acrylamide, 0.5 to 1 part of 2-hydroxyethyl acrylate, 150 to 200 parts of initiator, 8000 to 8500 parts of styrene, 5000 to 5500 parts of butadiene, 300 to 400 parts of initiator, 25 to 30 parts of calcium oxide and 7000 to 11000 parts of deionized water.

[0022] Example 2: As an optimization of the above example, the initiator concentration is 20 wt % to 25 wt % of the ammonium persulfate aqueous solution.

[0023] Example 3: As an optimization of the above example, an interface enhancer for improving the bonding quality of the cementing interface is obtained by the following method: S1, adding the required amount of acrylic acid, acrylonitrile, acrylamide, 2-hydroxyethyl acrylate, a portion of styrene and a portion of deionized water into a reactor and mixing them evenly, evacuating the reactor and heating it once; S2, adding a portion of initiator to the reactor to cause a polymerization reaction; S3, adding a required amount of butadiene, a remaining amount of styrene, a remaining amount of initiator and a remaining amount of deionized water into the reactor and mixing them evenly, heating the reactor for a second time and keeping the temperature; S4, adding a required amount of calcium oxide to the reactor, stirring, and then cooling; S5, adjusting the pH value of the reaction product in the reaction kettle, filtering, and obtaining an interface enhancer for improving the bonding quality of the cementing interface.

[0024] Embodiment 4: As an optimization of the above embodiment, in step S1, the temperature is 60°C to 70°C during the first heating; in step S2, the reaction time is 1.0h to 1.5h.

[0025] Example 5: As an optimization of the above example, in step S3, during the second heating, the temperature is 95°C to 100°C, and the insulation time is 2.0h to 2.5h.

[0026] The reaction temperature often determines the progress of the polymerization reaction. Too high a temperature easily causes implosion, whereas too low a temperature makes it difficult to polymerize. The reaction time affects the monomer conversion rate, thereby affecting the molecular weight and physical and chemical properties of the synthesized product. The polymerization reaction time and temperature of the present invention are optimal.

[0027] Example 6: As an optimization of the above example, in step S5, the pH value of the reaction product in the reactor is adjusted to 7 to 9.

[0028] Example 7: An interface modified prefluid is obtained using the interface enhancer for improving the bonding quality of the second interface of cementing as described in the above example as a raw material. The raw materials include, by weight, 15 parts of the interface enhancer for improving the bonding quality of the second interface of cementing, 0.4 to 0.8 parts of suspending agent, 45 to 252 parts of weighting agent and 100 parts of water. The interface modified prefluid is obtained by the following method: the required amounts of the interface enhancer for improving the bonding quality of the second interface of cementing, the suspending agent and the weighting agent are sequentially added to the required amount of water, and the mixture is mixed to obtain the interface modified prefluid.

[0029] Embodiment 8: As an optimization of the above embodiment, the suspending agent is one or more of biopolysaccharides, cellulose derivatives, clay, bentonite, microsilica powder, vinyl gum, polyvinyl alcohol, and inorganic salts.

[0030] Example 9: As an optimization of the above example, the weighting agent is one or more of quartz sand, barite, iron ore powder, and iron oxide.

[0031] The interface enhancer used in the present invention for improving the bonding quality of the cementing interface has a drainage effect on the mud cake pores and causes the surface electron binding energy and element composition of the mud cake clay particles to evolve (i.e., mud cake activation), the cement slurry hydration ions penetrate into the mud cake and react chemically with the high-valent metal ions in the mud cake to generate cementing products to produce chemical consolidation and precipitation blockage, the formation of a cross-linked network at the interface between the cement ring and the mud cake, and the solidification of the mud cake (i.e., mud cake solidification), thereby greatly improving the bonding strength of the cementing interface. The interface modified pre-fluid formed with the interface enhancer used in the present invention for improving the bonding quality of the cementing interface as a raw material can effectively improve the bonding strength of the cementing interface, and the bonding quality of the cementing interface is significantly improved, thereby achieving the purpose of preventing annular air channeling or annular pressure.

[0032] Embodiment 10: Preparation of the interface enhancer for improving the bonding quality of the cementing interface: S1, adding 45 parts of acrylic acid, 2.0 parts of acrylonitrile, 2.0 parts of acrylamide, 0.5 parts of 2-hydroxyethyl acrylate, 450 parts of styrene and 2500 parts of deionized water into a reactor and mixing them well, evacuating the reactor and heating it once to 60° C.; S2, adding 150 parts of initiator (aqueous solution of ammonium persulfate with a concentration of 20 wt%) into the reactor to cause a polymerization reaction for 1.0 h; S3, add 5000 parts of butadiene, 8000 parts of styrene, 150 parts of initiator (20 wt% ammonium persulfate aqueous solution) and 6500 parts of deionized water into the reactor and mix well, heat the reactor twice to 95°C and keep it warm for 2.0 hours; S4, adding 25 parts of calcium oxide into the reactor, stirring, and then cooling; S5, adjusting the pH value of the reaction product in the reactor to 7, filtering, and obtaining an interface enhancer for improving the bonding quality of the second interface of cementing.

[0033] Preparation of the interface modification pre-liquid: 15 parts of an interface enhancer for improving the bonding quality of the cementing interface, 0.4 parts of a suspending agent (biopolysaccharide), and 45 parts of a weighting agent (quartz sand) were added to 100 parts of water in sequence and mixed well to obtain an interface modified pre-fluid.

[0034] Embodiment 11: Preparation of the interface enhancer for improving the bonding quality of the cementing interface: S1, 55 parts of acrylic acid, 2.5 parts of acrylonitrile, 2.5 parts of acrylamide, 1.0 parts of 2-hydroxyethyl acrylate, 550 parts of styrene and 3500 parts of deionized water are added to a reactor and mixed, the reactor is evacuated, and the temperature is raised once to 70° C.; S2, adding 200 parts of initiator (aqueous solution of ammonium persulfate with a concentration of 25 wt%) into the reactor to cause a polymerization reaction for 1.5 hours; S3, add 5500 parts of butadiene, 8500 parts of styrene, 200 parts of initiator (25 wt% ammonium persulfate aqueous solution) and 7500 parts of deionized water into the reactor, mix well, heat the reactor twice to 100°C, and keep it warm for 2.5 hours; S4, adding 30 parts of calcium oxide into the reactor, stirring, and then cooling; S5, adjusting the pH value of the reaction product in the reactor to 9, filtering, and obtaining an interface enhancer for improving the bonding quality of the cementing interface.

[0035] Preparation of the interface modification pre-liquid: 15 parts of an interface enhancer for improving the bonding quality of the cementing interface, 0.8 parts of a suspending agent (clay), and 252 parts of a weighting agent (barite) were added to 100 parts of water in sequence and mixed well to obtain an interface modified pre-fluid.

[0036] Embodiment 12: Preparation of the interface enhancer for improving the bonding quality of the cementing interface: S1, 50 parts of acrylic acid, 2.2 parts of acrylonitrile, 2.2 parts of acrylamide, 0.8 parts of 2-hydroxyethyl acrylate, 500 parts of styrene and 3000 parts of deionized water are added to a reactor and mixed, the reactor is evacuated, and the temperature is raised once to 65° C.; S2, adding 180 parts of initiator (aqueous solution of ammonium persulfate with a concentration of 22 wt%) into the reactor to cause a polymerization reaction for 1.2 h; S3, add 5200 parts of butadiene, 8200 parts of styrene, 180 parts of initiator (22 wt% ammonium persulfate aqueous solution) and 7000 parts of deionized water into the reactor and mix well, heat the reactor twice to 98°C and keep it warm for 2.2 hours; S4, adding 28 parts of calcium oxide into the reactor, stirring, and then cooling; S5, adjusting the pH value of the reaction product in the reactor to 8, filtering, and obtaining an interface enhancer for improving the bonding quality of the cementing interface.

[0037] Preparation of the interface modification pre-liquid: 15 parts of an interface enhancer for improving the bonding quality of the cementing interface, 0.6 parts of a suspending agent (bentonite), and 200 parts of a weighting agent (iron ore powder) were added to 100 parts of water in sequence and mixed well to obtain an interface modified pre-fluid.

[0038] Embodiment 13: Preparation of the interface enhancer for improving the bonding quality of the cementing interface: S1, 50 parts of acrylic acid, 2.0 parts of acrylonitrile, 2.0 parts of acrylamide, 0.5 parts of 2-hydroxyethyl acrylate, 500 parts of styrene and 3000 parts of deionized water are added to a reactor and mixed, the reactor is evacuated, and the temperature is raised once to 60° C.; S2, adding 150 to 200 parts of an initiator (a 20 wt% ammonium persulfate aqueous solution) into the reactor to cause a polymerization reaction for 1.0 h; S3, adding 5000 parts of butadiene, 8000 parts of styrene, 150 parts of initiator (20 wt% ammonium persulfate aqueous solution) and 7000 parts of deionized water into the reactor and mixing them well, heating the reactor twice to a temperature of 95° C. to 100° C., and keeping the temperature for 2.0 h to 2.5 h; S4, adding 30 parts of calcium oxide into the reactor, stirring, and then cooling; S5, adjusting the pH value of the reaction product in the reactor to 8, filtering, and obtaining an interface enhancer for improving the bonding quality of the cementing interface.

[0039] Preparation of the interface modification pre-liquid: To 100 parts of water, 15 parts of an interface enhancer for improving the bonding quality of the cementing interface, 0.4 parts of a suspending agent (62 parts of bentonite, 18 parts of Wenlun gum, 10 parts of potassium chloride, 8 parts of polyvinyl alcohol), and 45 parts of a weighting agent (barite) were added in sequence and mixed evenly to obtain an interface modified pre-fluid.

[0040] Example 14: The difference from Example 13 is that the weight portion of the raw material suspending agent of the interface modification pre-liquid is changed to 0.5 parts, the weight portion of the weighting agent is changed to 60 parts, and the remaining steps are the same.

[0041] Example 15: The difference from Example 13 is that the weight portion of the raw material suspending agent of the interface modification pre-liquid is changed to 0.5 parts, the weight portion of the weighting agent is changed to 78 parts, and the remaining steps are the same.

[0042] Example 16: The difference from Example 13 is that the weight portion of the raw material suspending agent of the interface modification pre-liquid is changed to 0.55 parts, the weight portion of the weighting agent is changed to 97 parts, and the remaining steps are the same.

[0043] Example 17: The difference from Example 13 is that the weight portion of the raw material suspending agent of the interface modification pre-liquid is changed to 0.65 parts, the weight portion of the weighting agent is changed to 118 parts, and the remaining steps are the same.

[0044] Example 18: The difference from Example 13 is that the weight portion of the raw material suspending agent of the interface modification pre-liquid is changed to 0.67 parts, the weight portion of the weighting agent is changed to 140 parts, and the remaining steps are the same.

[0045] Example 19: The difference from Example 13 is that the weight portion of the raw material suspending agent of the interface modification pre-liquid is changed to 0.7 parts, the weight portion of the weighting agent is changed to 165 parts, and the remaining steps are the same.

[0046] Example 20: The difference from Example 13 is that the weight portion of the raw material suspending agent of the interface modification pre-liquid is changed to 0.75 parts, the weight portion of the weighting agent is changed to 191 parts, and the remaining steps are the same.

[0047] Example 21: The difference from Example 13 is that the weight portion of the raw material suspending agent of the interface modification pre-liquid is changed to 0.75 parts, the weight portion of the weighting agent is changed to 220 parts, and the remaining steps are the same.

[0048] Example 22: The difference from Example 13 is that the weight portion of the raw material suspending agent of the interface modification pre-liquid is changed to 0.8 parts, the weight portion of the weighting agent is changed to 252 parts, and the remaining steps are the same.

[0049] Embodiment 23: The interface enhancer for improving the bonding quality of the second interface of cementing obtained in Example 13 of the present invention was added to the isolation fluid base fluid to test its compatibility with the drilling fluid. The interface enhancer for improving the bonding quality of the second interface of cementing obtained in Example 13 of the present invention was prepared into an isolation base fluid with a concentration of 7%, 10% and 15% of the interface enhancer for improving the bonding quality of the second interface of cementing using an isolation fluid base fluid, and then the isolation fluid base fluids of the interface enhancer for improving the bonding quality of the second interface of cementing with different concentrations were mixed with water-based drilling fluid and oil-based drilling fluid in a ratio of 1:1, and the results were marked as water-based drilling fluid system 1 (water-based drilling fluid with a volume ratio of 1:1 and 7% of the interface enhancer for improving the bonding quality of the second interface of cementing), water-based drilling fluid system 2 (water-based drilling fluid with a volume ratio of 1:1 and 10% of the interface enhancer for improving the bonding quality of the second interface of cementing), and water-based drilling fluid system 1. System 3 (water-based drilling fluid with a volume ratio of 1:1 and 15% of the spacer fluid of the interface enhancer for improving the bonding quality of the second cementing interface), oil-based drilling fluid system 1 (oil-based drilling fluid with a volume ratio of 1:1 and 7% of the spacer fluid of the interface enhancer for improving the bonding quality of the second cementing interface), oil-based drilling fluid system 2 (oil-based drilling fluid with a volume ratio of 1:1 and 10% of the spacer fluid of the interface enhancer for improving the bonding quality of the second cementing interface), oil-based drilling fluid system 3 (oil-based drilling fluid with a volume ratio of 1:1 and 15% of the spacer fluid of the interface enhancer for improving the bonding quality of the second cementing interface), the performance of water-based drilling fluid system 1, 2, 3 and oil-based drilling fluid system 1, 2, 3 were tested respectively, and the performance indicators included viscosity and rheological parameters. Among them, Isolation fluid base liquid: Isolation fluid base liquid O-SP was purchased from Chengdu OMEC Petroleum Technology Co., Ltd.

[0050] The water-based drilling fluid consists of 3 parts of sorbitol laurate, 5 parts of polyoxyethylene sorbitan stearate, 1 part of sorbitol oleate and 91 parts of water.

[0051] The composition of the oil-based drilling fluid is: -35# diesel (freezing point -38°C) is used as the base oil. Based on the total mass of the oil-based drilling fluid being 100 parts, the oil-based drilling fluid also includes: 2.0 parts of tallic acid fatty amide (H1EMUL-1), 0.2 parts of OP-10 surfactant, 2.0 parts of hexadecyltrimethylammonium bromide, 0.4 parts of organic soil, 1.0 parts of oxidized asphalt and 1.0 parts of calcium oxide.

[0052] The performance test results are shown in Table 1. It can be seen from Table 1 that after the isolation fluid base fluid prepared with the interface enhancer for improving the bonding quality of the second interface of cementing with different proportions is mixed with the drilling fluid, the water loss is low and the adhesion and shearing have no obvious change, indicating that the interface enhancer for improving the bonding quality of the second interface of cementing of the present invention has good compatibility with the drilling fluid.

[0053] Embodiment 24: The interfacial modified pre-fluids obtained in Examples 13 to 22 of the present invention were evaluated for rheological properties and stability, with the test temperature being 90%. The rheological properties include density, rheological parameters (n, K) and fluidity, and the stability includes density difference, free liquid and water loss.

[0054] The test results are shown in Tables 3 and 4. It can be seen from Tables 3 and 4 that the density is 1.30 g / cm 3 Up to 2.20 g / cm 3 The interface modified pre-fluid of the present invention has good suspension stability and filtration loss control ability.

[0055] Embodiment 25: In order to cope with the situation of using oil-based drilling fluid during drilling, the interface modified pre-fluid (density 1.50 g / cm 3 ) The compatibility of downhole fluids was tested. The cement slurry is composed of Tianshan G-grade cement, 10% microsilicon, 1.0% sulfonated aldehyde ketone polycondensate dispersant, 1.0% clay high temperature stabilizer, 3.0% AMPS fluid loss agent, 1.0% polycarboxylic acid retarder and water. The water-cement ratio of the cement slurry is 0.44 and the density is 1.50g / cm 3 .

[0056] The test results are shown in Table 5. It can be seen from Table 5 that the interface modified pre-pad of the present invention has good compatibility with the oil-based drilling fluid. In a larger mutual ratio range, the performance of the oil-based drilling fluid is well maintained, with little change, and does not affect normal drilling construction. Similarly, the mixing of the interface modified pre-pad of the present invention with cement slurry will not shorten the thickening time of the cement slurry. The mixed liquid of the interface modified pre-pad, cement slurry and drilling fluid of the present invention can also maintain good rheological properties and a longer thickening time, indicating that the interface modified pre-pad of the present invention has good compatibility with cement slurry and oil-based drilling fluid.

[0057] Example 26: In the case of using water-based drilling fluid in the drilling process, the interface modified pre-fluid (density 1.50 g / cm 3 ) Compatibility of downhole fluids is tested.

[0058] The test results are shown in Table 6. It can be seen from Table 6 that the interface modified pre-pad fluid of the present invention has good compatibility with cement slurry and water-based drilling fluid.

[0059] Embodiment 27: The effect of the interface modified pre-fluid obtained in Example 13 of the present invention on the bonding strength of the cementing interface was tested. Test conditions: The spacer fluid base fluid and the interface modified pre-fluid obtained in Example 13 of the present invention were added to the water-based drilling fluid, respectively, with a ratio of 75:25, and a self-made imitation wellbore with an inner tube outer diameter of 33 mm and an outer tube inner diameter of 100 mm. The sample curing time was 3d, 7d, 15d and 30d, respectively, the curing method was bath curing, the curing temperature and pressure were 90°C × normal pressure, and the mud cake thickness was 0.3mm to 0.7mm, respectively.

[0060] The test method for the cementing interface bonding strength experiment was carried out according to the method specified in "MTA Method for Cementing Interface Overall Solidification Bonding Experiment" (Gu Jun, Qin Wenzheng, Petroleum Exploration and Development, 2010, 37 (2): 226-231). The demoulding force of the second interface of different samples was measured by a compressive strength tester, and then the second interface bonding strength was calculated by a conversion formula. The test results are shown in Table 7. It can be seen from Table 7 that in the water-based drilling fluid system, when the mud cake thickness does not exceed 0.5 mm, the cementing interface bonding strength of the mud cake formed by the drilling fluid added with the interface modified pre-fluid of the present invention is significantly improved, indicating that the interface modified pre-fluid of the present invention has a great influence on the improvement of the cementing interface bonding strength of the cementing interface, and can better improve the success rate of cementing construction.

[0061] In summary, it can be seen that the interface enhancer for improving the bonding quality of the second cementing interface of the present invention has good compatibility with the drilling fluid. The interface modified prefluid obtained by using the interface enhancer for improving the bonding quality of the second cementing interface of the present invention as a raw material has good suspension stability and filtration control ability, can effectively improve the bonding strength of the second cementing interface, and the bonding quality of the second cementing interface is significantly improved, thereby achieving the purpose of preventing annular air breakthrough or annular pressure.

[0062] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Non-essential technical features can be added or reduced according to actual needs to meet the requirements of different situations.

Claims

1. An interface enhancer for improving the bonding quality of cementing interfaces, characterized in that The raw materials include, by weight, 8450 to 9050 parts of styrene, 45 to 55 parts of acrylic acid, 2.0 to 2.5 parts of acrylonitrile, 2.0 to 2.5 parts of acrylamide, 0.5 to 1 part of 2-hydroxyethyl acrylate, 150 to 200 parts of initiator, 8000 to 8500 parts of styrene, 5000 to 5500 parts of butadiene, 300 to 400 parts of initiator, 25 to 30 parts of calcium oxide and 7000 to 11000 parts of deionized water; wherein the initiator concentration is 20wt% to 25wt% of an aqueous solution of ammonium persulfate.

2. The interface enhancer for improving the bonding quality of the cementing interface according to claim 1, characterized in that Obtained as follows: S1, adding the required amount of acrylic acid, acrylonitrile, acrylamide, 2-hydroxyethyl acrylate, a portion of styrene and a portion of deionized water into a reactor and mixing them evenly, evacuating the reactor and heating it once; S2, adding a portion of initiator to the reactor to cause a polymerization reaction; S3, adding a required amount of butadiene, a remaining amount of styrene, a remaining amount of initiator and a remaining amount of deionized water into the reactor and mixing them evenly, heating the reactor for a second time and keeping the temperature; S4, adding a required amount of calcium oxide to the reactor, stirring, and then cooling; S5, adjusting the pH value of the reaction product in the reaction kettle, filtering, and obtaining an interface enhancer for improving the bonding quality of the cementing interface.

3. The interface enhancer for improving the bonding quality of the cementing interface according to claim 1 or 2, characterized in that In step S1, the temperature is 60°C to 70°C during the first heating; or / and, in step S2, the reaction time is 1.0h to 1.5h; or / and, in step S3, the temperature is 95°C to 100°C during the second heating, and the insulation time is 2.0h to 2.5h; or / and, in step S5, the pH value of the reaction product in the reactor is adjusted to 7 to 9.

4. A method for preparing an interface enhancer for improving the bonding quality of cementing interfaces according to claim 1 or 3, characterized in that Proceed as follows: S1, adding the required amount of acrylic acid, acrylonitrile, acrylamide, 2-hydroxyethyl acrylate, a portion of styrene and a portion of deionized water into a reactor and mixing them evenly, evacuating the reactor and heating it once; S2, adding a portion of initiator to the reactor to cause a polymerization reaction; S3, adding a required amount of butadiene, a remaining amount of styrene, a remaining amount of initiator and a remaining amount of deionized water into the reactor and mixing them evenly, heating the reactor for a second time and keeping the temperature; S4, adding a required amount of calcium oxide to the reactor, stirring, and then cooling; S5, adjusting the pH value of the reaction product in the reaction kettle, filtering, and obtaining an interface enhancer for improving the bonding quality of the cementing interface.

5. An interface modified pre-fluid prepared with the interface enhancer for improving the bonding quality of the cementing interface as claimed in claim 1, 2 or 3 as one of the raw materials, characterized in that The raw materials include, by weight, 15 parts of an interface enhancer for improving the bonding quality of the second interface of cementing, 0.4 to 0.8 parts of a suspending agent, 45 to 252 parts of a weighting agent and 100 parts of water, and are obtained by the following method: the interface enhancer, suspending agent and weighting agent in required amounts are sequentially added to a required amount of water to improve the bonding quality of the second interface of cementing, and the interface modified pre-fluid is obtained after mixing.

6. The interface modified pre-fluid according to claim 5, characterized in that The suspending agent is one or more of biopolysaccharides, cellulose derivatives, clay, bentonite, microsilica powder, vinyl gum, polyvinyl alcohol, and inorganic salts.

7. The interface modified pre-fluid according to claim 5 or 6, characterized in that The weighting agent is one or more of quartz sand, barite, iron ore powder and iron oxide.

8. A method for preparing an interface modified pre-fluid according to claim 6 or 7, characterized in that The raw materials include 15 parts by weight of an interface enhancer for improving the bonding quality of the second interface of cementing, 0.4 to 0.8 parts of a suspending agent, 45 to 252 parts of a weighting agent and 100 parts of water, and are carried out in the following manner: the required amounts of the interface enhancer for improving the bonding quality of the second interface of cementing, the suspending agent and the weighting agent are sequentially added into the required amount of water, and the mixture is evenly mixed to obtain an interface modified pre-fluid.

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