A new type of solid scale inhibitor for oil wells

Abstract

The invention discloses a novel solid scale inhibitor for oil wells, belongs to the technical field of petroleum extraction, and specifically relates to a preparation method of a novel solid scale inhibitor for oil wells; the preparation method comprises first mixing hydroxyethylidene diphosphonic acid and acrylic acid-2-acrylamide-2-methylpropanesulfonic acid copolymer, then adding a desiccant and a scale inhibitor dispersant, mixing evenly, drying and granulating to prepare the novel solid scale inhibitor for oil wells; the scale inhibitor dispersant comprises at least a phosphine-based polymer and a sulfonated polyaryletherketonesulfone derivative; the desiccant comprises quicklime, biotite and illite. The invention is a novel solid scale inhibitor for oil wells with a high calcium ion scale inhibition rate and excellent sustained release performance, which not only helps to improve the scale inhibition rate of inorganic salt ions, but also can hinder the formation of scale bodies for a long time.

Description

Technical Field

[0001] The invention relates to the technical field of petroleum exploitation, and in particular to a novel solid scale inhibitor for oil wells. Background Art

[0002] The exploitation of oil fields is divided into three stages, namely primary oil recovery, secondary oil recovery and tertiary oil recovery. Primary oil recovery is a method of oil recovery that relies solely on various natural energies such as rock expansion, gravity, and natural gas expansion; secondary oil recovery is a method of oil recovery that increases the pressure of the oil layer by injecting water or gas; tertiary oil recovery is a physical and chemical method that changes tension by injecting chemicals and changes viscosity by injecting fluids to displace discontinuous and difficult-to-extract crude oil in the oil layer.

[0003] With the continuous exploitation of oil fields, the natural energy of primary oil production will be exhausted over time, and it is necessary to inject water into the oil layer on the ground to drive out the oil for secondary oil production. In the process of water reinjection into the well and gathering and transportation, on the one hand, the injected water contains anions such as sulfate, carbonate, and bicarbonate, while the formation water is rich in cations such as calcium, magnesium, and barium. On the other hand, due to changes in external conditions such as temperature and pressure, the solution becomes incompatible, and carbonate scale and sulfate scale are easily formed, causing scaling and blockage of the gathering and transportation system, reducing the mining efficiency. In order to solve the scaling problem of oil wells, it is necessary to add scale inhibitors to the oil wells. There are the following problems in adding liquid scale inhibitors: First, when adding liquid agents, high-pressure injection pumps, containers, pump trucks and other equipment and facilities are required, and continuous addition on site is inconvenient; second, the liquid agent will flow away with the produced fluid or adhere to the pipe wall, and cannot reach the bottom of the well. Therefore, there is an urgent need for a new solid scale inhibitor for oil wells with a high calcium ion scale inhibition rate and excellent slow release performance. Summary of the invention

[0004] The object of the present invention is to provide a novel solid scale inhibitor for oil wells which has high calcium ion scale inhibition rate and excellent slow-release performance.

[0005] The technical solution adopted by the present invention to achieve the above-mentioned purpose is: A method for preparing a novel solid scale inhibitor for oil wells comprises the following steps: firstly mixing hydroxyethylidene diphosphonic acid and acrylic acid-2-acrylamide-2-methylpropane sulfonic acid copolymer, then adding a desiccant and a scale inhibitor dispersant, mixing evenly, and drying and granulating to prepare the novel solid scale inhibitor for oil wells; the scale inhibitor dispersant comprises at least a phosphine-based polymer and a sulfonated polyaryletherketonesulfone derivative, the phosphine-based polymer having a phosphorus element and a benzene ring group, and the sulfonated polyaryletherketonesulfone derivative having a sulfonic group and a carboxyl group.

[0006] The invention uses phosphine-based polymers and sulfonated polyaryletherketonesulfone derivatives as anti-scaling dispersants, and mixes them with hydroxyethylidene diphosphonic acid, acrylic acid-2-acrylamide-2-methylpropanesulfonic acid copolymer, quicklime, biotite and illite for granulation to prepare a novel solid scale inhibitor for oil wells; the novel solid scale inhibitor for oil wells has good scale inhibition performance and relatively excellent release performance, and can slowly release the effective components in the novel solid scale inhibitor for oil wells and finally completely integrate them into the medium, so as to achieve the purpose of long-term obstruction of scale formation and improve the scale inhibition rate of inorganic salt ions.

[0007] Preferably, the mass ratio of hydroxyethylidene diphosphonic acid to acrylic acid-2-acrylamide-2-methylpropane sulfonic acid copolymer is 1:2-5.

[0008] Preferably, the mass ratio of hydroxyethylidene diphosphonic acid to the desiccant is 1:1-5.

[0009] Preferably, the desiccant comprises quicklime, biotite and illite, the mass ratio of quicklime to biotite is 1:1-2, and the mass ratio of quicklime to illite is 1:1-2.

[0010] Preferably, the mass ratio of hydroxyethylidene diphosphonic acid to the scale inhibitor and dispersant is 1:0.2-0.6.

[0011] Preferably, the mass ratio of the phosphine-based polymer to the sulfonated poly(aryletherketonesulfone) derivative is 1:0.5-2.

[0012] Preferably, in the preparation of the phosphine-based polymer, 4-phenylvinylmagnesium bromide is first reacted with phosphorus trichloride, and then a free radical polymerization reaction is performed to obtain the phosphine-based polymer.

[0013] Preferably, the preparation of the phosphine-based polymer is specifically, Weigh 4-phenylvinylmagnesium bromide and phosphorus trichloride, add tetrahydrofuran, react for 6-18 hours in a water bath at 2-10°C, add a saturated ammonium chloride solution, shake, add n-hexane, take the supernatant, add azobisisobutyronitrile, stir evenly, pass argon for 20-40 minutes, heat at 80-120°C for 12-36 hours, wash with ethanol 2-5 times, and vacuum dry at 55-75°C to obtain a phosphine-based polymer.

[0014] More preferably, the molar ratio of 4-phenylvinylmagnesium bromide to phosphorus trichloride is 1:1-2.

[0015] More preferably, the usage ratio of 4-phenylvinylmagnesium bromide to tetrahydrofuran is 1 mmol: 1-5 mL.

[0016] More preferably, the usage ratio of 4-phenylvinylmagnesium bromide and saturated ammonium chloride solution is 1 mmol: 1-5 mL.

[0017] More preferably, the volume ratio of tetrahydrofuran to the saturated ammonium chloride solution is 1:10-30.

[0018] More preferably, the volume ratio of the saturated ammonium chloride solution to n-hexane is 1:1-2.

[0019] More preferably, the usage ratio of the saturated ammonium chloride solution to azobisisobutyronitrile is 1 mL: 1-5 mg.

[0020] Preferably, in the preparation of the sulfonated polyaryletherketonesulfone derivative, bisphenol A and 4,4'-difluorobenzophenone are first mixed, and then 3,3'-disulfonated-4,4'-dichlorophenylsulfone and 4-carboxyphenylhydroquinone are added to react to obtain the sulfonated polyaryletherketonesulfone derivative.

[0021] Preferably, the preparation of the sulfonated polyaryletherketonesulfone derivative comprises: First, bisphenol A and 4,4'-difluorobenzophenone are mixed evenly, and then 3,3'-disulfonated-4,4'dichlorophenyl sulfone and 4-carboxyphenyl hydroquinone are added, and toluene and cyclopentane are added and stirred evenly, potassium carbonate is added and stirred evenly at 30-60° C., reacted at 100-150° C. for 2-5 hours, stirred at 150-200° C. for 12-36 hours, washed with boiling water until the water is clear, and dried to obtain a sulfonated polyaryletherketonesulfone derivative.

[0022] More preferably, the mass ratio of bisphenol A to 4,4'-difluorobenzophenone is 1:1-2.

[0023] More preferably, the mass ratio of bisphenol A to 3,3'-disulfonated-4,4'-dichlorophenyl sulfone is 1:1-2.

[0024] More preferably, the mass ratio of bisphenol A to 4-carboxyphenylhydroquinone is 1:0.2-1.

[0025] More preferably, the mass ratio of bisphenol A to potassium carbonate is 1:1-5.

[0026] More preferably, the usage ratio of bisphenol A to toluene is 1 g: 2-10 mL.

[0027] More preferably, the usage ratio of bisphenol A to sulfolane is 1 g:5-15 mL.

[0028] Preferably, a novel solid scale inhibitor for oil wells is prepared by: Firstly, hydroxyethylidene diphosphonic acid and acrylic acid-2-acrylamide-2-methylpropane sulfonic acid copolymer are mixed, then a desiccant is added, mixed evenly, and then dried and granulated to obtain a new solid scale inhibitor for oil wells.

[0029] More preferably, the mass ratio of hydroxyethylidene diphosphonic acid to acrylic acid-2-acrylamide-2-methylpropane sulfonic acid copolymer is 1:2-5.

[0030] More preferably, the mass ratio of hydroxyethylidene diphosphonic acid to the desiccant is 1:1-5.

[0031] More preferably, the desiccant includes quicklime, biotite and illite, the mass ratio of quicklime to biotite is 1:1-2, and the mass ratio of quicklime to illite is 1:1-2.

[0032] Preferably, in the preparation of a novel solid scale inhibitor for oil wells, a scale inhibitor dispersant is also added, specifically, Firstly, hydroxyethylidene diphosphonic acid and acrylic acid-2-acrylamide-2-methylpropane sulfonic acid copolymer are mixed, then a desiccant and a scale inhibitor dispersant are added, mixed evenly, and then dried and granulated to obtain a new solid scale inhibitor for oil wells.

[0033] More preferably, the mass ratio of hydroxyethylidene diphosphonic acid to acrylic acid-2-acrylamide-2-methylpropane sulfonic acid copolymer is 1:2-5.

[0034] More preferably, the mass ratio of hydroxyethylidene diphosphonic acid to the desiccant is 1:1-5.

[0035] More preferably, the desiccant includes quicklime, biotite and illite, the mass ratio of quicklime to biotite is 1:1-2, and the mass ratio of quicklime to illite is 1:1-2.

[0036] More preferably, the mass ratio of hydroxyethylene diphosphonic acid to the scale inhibitor and dispersant is 1:0.2-0.6.

[0037] More preferably, the scale inhibitor dispersant includes phosphine-based polymers and sulfonated polyaryletherketonesulfone derivatives. Phosphine-based polymers and sulfonated polyaryletherketonesulfone derivatives have a large number of hydrophilic groups, which not only have good scale inhibition and dispersibility, but also help to improve the scale inhibition effect on inorganic salt ions; they also have better release performance, which can slowly release the effective ingredients and finally completely integrate them into the medium, so as to achieve the purpose of long-term prevention of scale formation.

[0038] More preferably, the mass ratio of the phosphine-based polymer to the sulfonated poly(aryletherketonesulfone) derivative is 1:0.5-2.

[0039] Preferably, in the preparation of a novel solid scale inhibitor for oil wells, the scale inhibitor dispersant further comprises polyethylene glycol triphenylphosphine. Polyethylene glycol triphenylphosphine has good swelling properties and can further improve the scale inhibition performance and slow-release performance of the novel solid scale inhibitor for oil wells.

[0040] More preferably, the scale inhibitor-dispersant includes a phosphine-based polymer, a sulfonated polyaryletherketonesulfone derivative, and polyethylene glycol triphenylphosphine.

[0041] More preferably, the mass ratio of the phosphine-based polymer to the sulfonated poly(aryletherketonesulfone) derivative is 1:0.5-2.

[0042] More preferably, the mass ratio of the phosphine-based polymer to polyethylene glycol triphenylphosphine is 1:0.5-1.

[0043] The invention also discloses a novel solid scale inhibitor for oil wells prepared by any of the above methods.

[0044] The invention also discloses the use of a novel solid scale inhibitor for oil wells in removing scale samples from oil wells.

[0045] Since the present invention adopts phosphine-based polymer, sulfonated polyaryletherketonesulfone derivative and polyethylene glycol triphenylphosphine as scale inhibitor dispersant to prepare novel solid scale inhibitor for oil well, it has the following beneficial effects: the novel solid scale inhibitor for oil well prepared by the present invention has good scale inhibition performance, and the calcium ion scale inhibition rate is more than 98%; the novel solid scale inhibitor for oil well prepared by the present invention has better slow release performance, and the average slow release rate is more than 3.8g / h. Therefore, the present invention is a novel solid scale inhibitor for oil well with good scale inhibition performance and excellent slow release performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is the calcium ion scale inhibition rate of the novel solid scale inhibitor for oil wells of the present invention.

[0047] Figure 2 It is the average sustained release rate of the novel solid scale inhibitor for oil wells of the present invention. DETAILED DESCRIPTION

[0048] The present invention is further described in detail below in conjunction with specific embodiments, and the examples provided are only for illustrating the present invention, rather than for limiting the scope of the present invention. The examples provided below can be used as a guide for further improvements by those of ordinary skill in the art, and do not constitute a limitation of the present invention in any way.

[0049] The experimental methods in the following examples are conventional methods unless otherwise specified. The materials, reagents, etc. used in the following examples are commercially available unless otherwise specified.

[0050] Embodiment 1: S1. Preparation of a new solid scale inhibitor for oil wells, comprising: First, hydroxyethylene diphosphonic acid and acrylic acid-2-acrylamide-2-methylpropane sulfonic acid copolymer are mixed, and then a desiccant is added and mixed evenly, and then dried and granulated to obtain a new solid scale inhibitor for oil wells. The mass ratio of hydroxyethylene diphosphonic acid and acrylic acid-2-acrylamide-2-methylpropane sulfonic acid copolymer is 1:3; the mass ratio of hydroxyethylene diphosphonic acid and desiccant is 1:2; the desiccant includes quicklime, biotite and illite, the mass ratio of quicklime to biotite is 1:1, and the mass ratio of quicklime to illite is 1:1.

[0051] Embodiment 2: S1. Preparation of phosphine-based polymers, comprising: Weigh 4-phenylvinylmagnesium bromide and phosphorus trichloride, add tetrahydrofuran, react for 12 hours in a water bath at 10°C, add saturated ammonium chloride solution, shake, add n-hexane, take the supernatant, add azobisisobutyronitrile, stir evenly, pass argon for 30 minutes, heat at 100°C for 24 hours, wash with ethanol 5 times, and vacuum dry at 60°C to obtain a phosphine-based polymer. The molar ratio of 4-phenylvinylmagnesium bromide and phosphorus trichloride is 1:1; the dosage ratio of 4-phenylvinylmagnesium bromide and tetrahydrofuran is 1mmol:1.5mL; the dosage ratio of 4-phenylvinylmagnesium bromide and saturated ammonium chloride solution is 1mmol:1.5mL; the volume ratio of tetrahydrofuran and saturated ammonium chloride solution is 1:20; the volume ratio of saturated ammonium chloride solution and n-hexane is 1:1; the dosage ratio of saturated ammonium chloride solution and azobisisobutyronitrile is 1mL:1.8mg.

[0052] S2. Preparation of sulfonated polyaryletherketonesulfone derivatives, comprising: First, bisphenol A and 4,4'-difluorobenzophenone are mixed evenly, then 3,3'-disulfonated-4,4'dichlorophenyl sulfone and 4-carboxyphenyl hydroquinone are added, toluene and cyclopentane are added and stirred evenly, potassium carbonate is added and stirred evenly at 40°C, reacted at 125°C for 4h, stirred at 185°C for 24h, washed with boiling water until the water is clear, and dried to obtain a sulfonated polyaryletherketonesulfone derivative. The mass ratio of bisphenol A to 4,4'-difluorobenzophenone is 1:1; the mass ratio of bisphenol A to 3,3'-disulfonated-4,4'dichlorophenyl sulfone is 1:1; the mass ratio of bisphenol A to 4-carboxyphenyl hydroquinone is 1:0.5; the mass ratio of bisphenol A to potassium carbonate is 1:2.5; the amount ratio of bisphenol A to toluene is 1g:5mL; the amount ratio of bisphenol A to cyclopentane is 1g:7mL.

[0053] S3. Preparation of a new solid scale inhibitor for oil wells, comprising: First, hydroxyethylene diphosphonic acid and acrylic acid-2-acrylamide-2-methylpropane sulfonic acid copolymer are mixed, and then a desiccant and a scale inhibitor dispersant are added. After the mixture is evenly mixed, the mixture is dried and granulated to obtain a new solid scale inhibitor for oil wells. The mass ratio of hydroxyethylene diphosphonic acid and acrylic acid-2-acrylamide-2-methylpropane sulfonic acid copolymer is 1:3; the mass ratio of hydroxyethylene diphosphonic acid and the desiccant is 1:2; the desiccant includes quicklime, biotite and illite, the mass ratio of quicklime to biotite is 1:1, and the mass ratio of quicklime to illite is 1:1; the mass ratio of hydroxyethylene diphosphonic acid and the scale inhibitor dispersant is 1:0.4; the scale inhibitor dispersant includes the phosphine-based polymer prepared in step S1 of this embodiment and the sulfonated polyaryletherketonesulfone derivative prepared in step S2 of this embodiment, and the mass ratio of the phosphine-based polymer to the sulfonated polyaryletherketonesulfone derivative is 1:1.

[0054] Embodiment 3: S1. Preparation of phosphine-based polymer, same as step S1 of Example 2.

[0055] S2. Preparation of sulfonated poly(aryl ether ketone sulfone) derivatives, same as step S2 of Example 2.

[0056] S3. Preparation of a new solid scale inhibitor for oil wells, except that the mass ratio of hydroxyethylidene diphosphonic acid to the scale inhibitor dispersant is changed to 1:0.3, the scale inhibitor dispersant includes the phosphine-based polymer prepared in step S1 of this embodiment and the sulfonated polyaryletherketonesulfone derivative prepared in step S2 of this embodiment, and the mass ratio of the phosphine-based polymer to the sulfonated polyaryletherketonesulfone derivative is 1:2, and other conditions are the same as step S3 of embodiment 2.

[0057] Embodiment 4: S1. Preparation of phosphine-based polymer, same as step S1 of Example 2.

[0058] S2. Preparation of sulfonated poly(aryl ether ketone sulfone) derivatives, same as step S2 of Example 2.

[0059] S3. Preparation of a new solid scale inhibitor for oil wells, except that the mass ratio of hydroxyethylidene diphosphonic acid to the scale inhibitor dispersant is changed to 1:0.3, the scale inhibitor dispersant includes the phosphine-based polymer prepared in step S1 of this embodiment and the sulfonated polyaryletherketonesulfone derivative prepared in step S2 of this embodiment, and the mass ratio of the phosphine-based polymer to the sulfonated polyaryletherketonesulfone derivative is 1:0.5, and other conditions are the same as step S3 of embodiment 2.

[0060] Embodiment 5: S1. Preparation of phosphine-based polymer, same as step S1 of Example 2.

[0061] S2. Preparation of sulfonated poly(aryl ether ketone sulfone) derivatives, same as step S2 of Example 2.

[0062] S3. Preparation of a new solid scale inhibitor for oil wells, comprising: First, hydroxyethylene diphosphonic acid and acrylic acid-2-acrylamide-2-methylpropane sulfonic acid copolymer are mixed, and then a desiccant and a scale inhibitor dispersant are added. After the mixture is evenly mixed, the mixture is dried and granulated to obtain a new solid scale inhibitor for oil wells. The mass ratio of hydroxyethylene diphosphonic acid and acrylic acid-2-acrylamide-2-methylpropane sulfonic acid copolymer is 1:3; the mass ratio of hydroxyethylene diphosphonic acid and the desiccant is 1:2; the desiccant includes quicklime, biotite and illite, the mass ratio of quicklime to biotite is 1:1, and the mass ratio of quicklime to illite is 1:1; the mass ratio of hydroxyethylene diphosphonic acid and the scale inhibitor dispersant is 1:0.6; the scale inhibitor dispersant includes the phosphine-based polymer prepared in step S1 of this embodiment, the sulfonated polyaryletherketonesulfone derivative and polyethylene glycol triphenylphosphine prepared in step S2 of this embodiment, the mass ratio of the phosphine-based polymer to the sulfonated polyaryletherketonesulfone derivative is 1:1, and the mass ratio of the phosphine-based polymer to the polyethylene glycol triphenylphosphine is 1:1.

[0063] Embodiment 6: S1. Preparation of phosphine-based polymer, same as step S1 of Example 2.

[0064] S2. Preparation of sulfonated poly(aryl ether ketone sulfone) derivatives, same as step S2 of Example 2.

[0065] S3. Preparation of a novel solid scale inhibitor for oil wells, except that the mass ratio of hydroxyethylidene diphosphonic acid and the scale inhibitor dispersant is changed to 1:0.5, the scale inhibitor dispersant comprises the phosphine-based polymer prepared in step S1 of this embodiment, the sulfonated polyaryletherketonesulfone derivative and polyethylene glycol triphenylphosphine prepared in step S2 of this embodiment, the mass ratio of the phosphine-based polymer to the sulfonated polyaryletherketonesulfone derivative is 1:1, and the mass ratio of the phosphine-based polymer to the polyethylene glycol triphenylphosphine is 1:0.5, and other conditions are the same as step S3 of embodiment 5.

[0066] Comparative Example 1: S1. Preparation of phosphine-based polymer, same as step S1 of Example 2.

[0067] S2. Preparation of a new solid scale inhibitor for oil wells, comprising: First, hydroxyethylene diphosphonic acid and acrylic acid-2-acrylamide-2-methylpropane sulfonic acid copolymer are mixed, and then a desiccant and a scale inhibitor dispersant are added. After the mixture is evenly mixed, the mixture is dried and granulated to obtain a new solid scale inhibitor for oil wells. The mass ratio of hydroxyethylene diphosphonic acid and acrylic acid-2-acrylamide-2-methylpropane sulfonic acid copolymer is 1:3; the mass ratio of hydroxyethylene diphosphonic acid and the desiccant is 1:2; the desiccant includes quicklime, biotite and illite, the mass ratio of quicklime to biotite is 1:1, and the mass ratio of quicklime to illite is 1:1; the mass ratio of hydroxyethylene diphosphonic acid and the scale inhibitor dispersant is 1:0.2, and the scale inhibitor dispersant includes the phosphine-based polymer prepared in step S1 of this comparative example.

[0068] Comparative Example 2: S1. Preparation of sulfonated poly(aryl ether ketone sulfone) derivatives, same as step S2 of Example 2.

[0069] S2. Preparation of a new solid scale inhibitor for oil wells, comprising: First, hydroxyethylene diphosphonic acid and acrylic acid-2-acrylamide-2-methylpropane sulfonic acid copolymer are mixed, and then a desiccant and a scale inhibitor dispersant are added. After mixing evenly, the mixture is dried and granulated to obtain a new solid scale inhibitor for oil wells. The mass ratio of hydroxyethylene diphosphonic acid and acrylic acid-2-acrylamide-2-methylpropane sulfonic acid copolymer is 1:3; the mass ratio of hydroxyethylene diphosphonic acid and the desiccant is 1:2; the desiccant includes quicklime, biotite and illite, the mass ratio of quicklime to biotite is 1:1, and the mass ratio of quicklime to illite is 1:1; the mass ratio of hydroxyethylene diphosphonic acid and the scale inhibitor dispersant is 1:0.2, and the scale inhibitor dispersant includes the sulfonated polyaryletherketonesulfone derivative prepared in step S1 of this comparative example.

[0070] Comparative Example 3: S1. Preparation of a new solid scale inhibitor for oil wells, comprising: First, hydroxyethylene diphosphonic acid and acrylic acid-2-acrylamide-2-methylpropane sulfonic acid copolymer are mixed, and then a desiccant and a scale inhibitor dispersant are added. After the mixture is evenly mixed, the mixture is dried and granulated to obtain a new solid scale inhibitor for oil wells. The mass ratio of hydroxyethylene diphosphonic acid and acrylic acid-2-acrylamide-2-methylpropane sulfonic acid copolymer is 1:3; the mass ratio of hydroxyethylene diphosphonic acid and the desiccant is 1:2; the desiccant includes quicklime, biotite and illite, the mass ratio of quicklime to biotite is 1:1, and the mass ratio of quicklime to illite is 1:1; the mass ratio of hydroxyethylene diphosphonic acid and the scale inhibitor dispersant is 1:0.2, and the scale inhibitor dispersant includes polyethylene glycol triphenylphosphine.

[0071] Experimental example: 1. Determination of scale inhibition performance of new solid scale inhibitor for oil wells In the simulated oilfield anti-scaling solution, the new solid scale inhibitor for oil wells was not added. After 72 hours of treatment, the calcium ion concentration (mg / L) of the blank group without the new solid scale inhibitor for oil wells was determined by EDTA titration method; in the simulated oilfield anti-scaling solution, the new solid scale inhibitor for oil wells was added. After 72 hours of treatment, the calcium ion concentration (mg / L) of the treatment group with the new solid scale inhibitor for oil wells was determined by EDTA titration method; the calcium ion concentration (mg / L) in the simulated oilfield anti-scaling solution was determined by EDTA titration method. Calcium ion scale inhibition rate (%) = (calcium ion concentration of the treatment group with the new solid scale inhibitor for oil wells - calcium ion concentration of the blank group without the new solid scale inhibitor for oil wells) / (calcium ion concentration in the simulated oilfield anti-scaling solution - calcium ion concentration of the blank group without the new solid scale inhibitor for oil wells) × 100%.

[0072] The composition of oil well scale samples is mainly calcium carbonate scale precipitation. When calcium carbonate precipitation is just crystallized in the oil field produced fluid, it has a large surface energy and is easily adsorbed to the surface of the oil well pipe. Therefore, only by effectively inhibiting the scaling trend of calcium ions in the oil field can the purpose of oil well scale inhibition be effectively achieved. In the oil well, the content of calcium carbonate, calcium bicarbonate and carbon dioxide maintains a certain dynamic balance. When the temperature and pressure in the oil well change, these ions may be further promoted to combine to form precipitation, resulting in increased difficulty in scale inhibition of calcium ions.

[0073] Figure 1 is the calcium ion scale inhibition rate of the novel solid scale inhibitor for oil wells of the present invention. Figure 1 It can be seen that the calcium ion scale inhibition rate of Example 2-4 is higher than that of Example 1 because in Example 2-4, an additional scale inhibitor dispersant is added in the preparation of the new solid scale inhibitor for oil wells, and the scale inhibitor dispersant includes a phosphine-based polymer and a sulfonated polyaryletherketonesulfone derivative; the calcium ion scale inhibition rate of Example 2 is higher than that of Example 3-4 because the amounts of the phosphine-based polymer and the sulfonated polyaryletherketonesulfone derivative used in the scale inhibitor dispersant are different. The calcium ion scale inhibition rate of Example 2 is higher than that of Comparative Example 2-3 because in the scale inhibitor dispersant, Comparative Example 2 only includes a phosphine-based polymer, and Comparative Example 3 only includes a sulfonated polyaryletherketonesulfone derivative. This shows that in the preparation of the new solid scale inhibitor for oil wells, the phosphine-based polymer and the sulfonated polyaryletherketonesulfone derivative are added in coordination as a scale inhibitor dispersant to prepare the new solid scale inhibitor for oil wells, so that the effect of improving the calcium ion scale inhibition rate is better.

[0074] The calcium ion scale inhibition rate of Example 5 is higher than that of Example 2 because Example 5 also includes polyethylene glycol triphenylphosphine in the scale inhibitor dispersant; the calcium ion scale inhibition rate of Example 5 is higher than that of Example 6 because the amount of polyethylene glycol triphenylphosphine used is different; the calcium ion scale inhibition rate of Example 5 is higher than that of Comparative Example 4 because Comparative Example 4 only includes polyethylene glycol triphenylphosphine in the scale inhibitor dispersant; this shows that in the preparation of the new solid scale inhibitor for oil wells, further adding polyethylene glycol triphenylphosphine as a scale inhibitor dispersant can further improve the calcium ion scale inhibition rate in the oil well.

[0075] 2. Determination of slow-release performance of new solid scale inhibitor for oil wells The sustained-release properties of the new solid scale inhibitors for oil wells prepared in Examples 1-6 and Comparative Examples 1-3 were respectively measured by the weight loss method. The measuring method is as follows: the new solid scale inhibitor for oil wells is punched with holes, weighed, and the initial mass of the new solid scale inhibitor for oil wells is recorded. A thin rope is then passed through the new solid scale inhibitor for oil wells and hung in a 1000 mL beaker, and the beaker is kept immersed in the center of the simulated scaling solution to allow the new solid scale inhibitor for oil wells to be slowly released in the simulated scaling solution. The average release rate (g / h) is calculated by the release time when the new solid scale inhibitor for oil wells is completely dissolved. The average release rate (g / h) = initial mass of the new solid scale inhibitor for oil wells / release time when the new solid scale inhibitor for oil wells is completely dissolved.

[0076] Figure 2 is the average slow release rate of the novel solid scale inhibitor for oil wells of the present invention. Figure 2 It can be seen that the average release rate of Example 2-4 is higher than that of Example 1 because in Example 2-4, an additional scale inhibitor dispersant is added in the preparation of the new solid scale inhibitor for oil wells, and the scale inhibitor dispersant includes a phosphine-based polymer and a sulfonated polyaryletherketonesulfone derivative; the average release rate of Example 2 is higher than that of Example 3-4 because the amount of the phosphine-based polymer and the sulfonated polyaryletherketonesulfone derivative used in the scale inhibitor dispersant is different. The average release rate of Example 2 is higher than that of Comparative Example 2-3 because in the scale inhibitor dispersant, Comparative Example 2 only includes a phosphine-based polymer, and Comparative Example 3 only includes a sulfonated polyaryletherketonesulfone derivative. This shows that in the preparation of the new solid scale inhibitor for oil wells, the phosphine-based polymer and the sulfonated polyaryletherketonesulfone derivative are added in coordination as a scale inhibitor dispersant to prepare the new solid scale inhibitor for oil wells, so that the effect of increasing the average release rate is better.

[0077] The average release rate of Example 5 is higher than that of Example 2 because Example 5 also includes polyethylene glycol triphenylphosphine in the scale inhibitor and dispersant; the average release rate of Example 5 is higher than that of Example 6 because the amount of polyethylene glycol triphenylphosphine used is different; the average release rate of Example 5 is higher than that of Comparative Example 4 because Comparative Example 4 only includes polyethylene glycol triphenylphosphine in the scale inhibitor and dispersant; this shows that in the preparation of the new solid scale inhibitor for oil wells, further adding polyethylene glycol triphenylphosphine as a scale inhibitor and dispersant can further improve the average release rate in the oil well.

[0078] The conventional operations in the operating steps of the present invention are well known to those skilled in the art and will not be described in detail here.

[0079] The embodiments described above provide a detailed description of the technical solutions of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, supplements or similar substitutions made within the scope of the principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a novel solid scale inhibitor for oil wells, comprising: first mixing hydroxyethylidene diphosphonic acid and acrylic acid-2-acrylamide-2-methylpropane sulfonic acid copolymer, then adding a scale inhibitor dispersant and a desiccant, mixing evenly, and drying and granulating to prepare the novel solid scale inhibitor for oil wells; the scale inhibitor dispersant at least comprises a phosphine-based polymer and a sulfonated polyaryletherketonesulfone derivative, the phosphine-based polymer has a phosphorus element and a benzene ring group, and the sulfonated polyaryletherketonesulfone derivative has a sulfonic group and a carboxyl group.

2. A novel solid scale inhibitor for oil wells according to claim 1, characterized in that: The mass ratio of the hydroxyethylidene diphosphonic acid to the acrylic acid-2-acrylamide-2-methylpropane sulfonic acid copolymer is 1:2-5.

3. The novel solid scale inhibitor for oil wells according to claim 1, characterized in that: The mass ratio of the hydroxyethylidene diphosphonic acid to the desiccant is 1:1-5.

4. The novel solid scale inhibitor for oil wells according to claim 1, characterized in that: The desiccant comprises quicklime, biotite and illite, wherein the mass ratio of the quicklime to the biotite is 1:1-2, and the mass ratio of the quicklime to the illite is 1:1-2.

5. The novel solid scale inhibitor for oil wells according to claim 1, characterized in that: The mass ratio of the hydroxyethylidene diphosphonic acid to the scale inhibitor dispersant is 1:0.2-0.

6.

6. A novel solid scale inhibitor for oil wells according to claim 1, characterized in that: The mass ratio of the phosphine-based polymer to the sulfonated polyaryletherketonesulfone derivative is 1:0.5-2.

7. A novel solid scale inhibitor for oil wells according to claim 1, characterized in that: In the preparation of the phosphine-based polymer, 4-phenylvinyl magnesium bromide is first reacted with phosphorus trichloride, and then a free radical polymerization reaction is performed to obtain the phosphine-based polymer.

8. The novel solid scale inhibitor for oil wells according to claim 1, characterized in that: In the preparation of the sulfonated polyaryletherketonesulfone derivative, bisphenol A and 4,4'-difluorobenzophenone are first mixed, and then 3,3'-disulfonated-4,4'-dichlorophenylsulfone and 4-carboxyphenylhydroquinone are added to react to obtain the sulfonated polyaryletherketonesulfone derivative.

9. A novel solid scale inhibitor for oil wells prepared by the method of any one of claims 1 to 8.

10. Use of the novel solid scale inhibitor for oil wells as claimed in claim 9 in removing scale samples from oil wells.

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