CN115260416B - Nano composite filtrate reducer for high-temperature-resistant water-based drilling fluid and preparation method thereof - Google Patents
Nano composite filtrate reducer for high-temperature-resistant water-based drilling fluid and preparation method thereof Download PDFInfo
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- C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
- C09K8/02—Well-drilling compositions
- C09K8/03—Specific additives for general use in well-drilling compositions
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- C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
- C09K8/02—Well-drilling compositions
- C09K8/04—Aqueous well-drilling compositions
- C09K8/14—Clay-containing compositions
- C09K8/18—Clay-containing compositions characterised by the organic compounds
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- C09K8/24—Polymers
Abstract
The invention relates to the technical field of petroleum drilling fluid, in particular to a nano composite filtrate reducer for high temperature resistant water-based drilling fluid and a preparation method thereof, wherein the filtrate reducer comprises acrylamide, N-vinyl pyrrolidone, 2-acrylamide-2-methylpropanesulfonic acid, cationic monomers and nanomaterial carbon points; the mass of the carbon dots of the nano material is 1.8-3% of the total mass of the monomer. The filtrate reducer and the preparation method thereof can effectively solve the problems of complex preparation process, high cost and easy hydrolysis of modified carbon dot ester groups in the prior art.
Description
Technical Field
The invention relates to the technical field of petroleum drilling fluid, in particular to a high-temperature-resistant water-based drilling fluid nano composite filtrate reducer and a preparation method thereof.
Background
The level of drilling fluid technology is directly related to the quality, progress and cost of drilling construction. Especially in the drilling process of deep wells and ultra-deep wells, the severe environment of high temperature and high pressure in the well can bring a plurality of complicated and troublesome problems to the construction process. In order to ensure smooth high-temperature drilling, the drilling fluid has good temperature resistance, and ensure that the drilling fluid can maintain various rheological parameter indexes without severe change even in an environment with the underground temperature exceeding 230 ℃. Meanwhile, under the high-temperature and high-salt complex environment, the polymer treating agent in the well drilling fluid of the well bore can generate high-temperature degradation, high-temperature crosslinking, high-temperature desorption, high-temperature dehydration and other high-temperature damage effects, so that the well drilling fluid is poor or even deteriorated, the requirements of the well drilling engineering cannot be met, the normal operation of the well drilling operation is seriously influenced, and the safety risk of the well drilling engineering of the deep well is greatly increased. The drilling fluid has large filtration loss, so that the water-sensitive stratum can absorb water and expand, the diameter is reduced, the drilling fluid is blocked, and a large section of hole is scratched; the hard brittle stratum (shale, broken dolomite and igneous rock) with micro-crack development collapses; the invasion of filtrate can cause the expansion of clay minerals in reservoirs, reduce seepage channels, increase the resistance of oil gas flowing into wells, reduce the relative permeability of the oil gas, and finally reduce the yield of the oil gas wells.
Compared with the conventional reservoir, the unconventional tight reservoir has strong heterogeneity, small pores and throats, mainly a nanoscale pore system, locally developed micron-millimeter pores, complex and various pore-throat structures with different microscale, various pore types, including intra-grain pores in organic matters, intra-grain pores in minerals, inter-grain pores between minerals and organic matters or between mineral particles and mineral particles, and microcracks.
The filtrate reducer is a treating agent which can be applied to the drilling process of an oil field and can effectively reduce the filtrate loss, and is a key material in the drilling fluid treating agent. The current research on polymer filtrate loss additives is mainly focused on improving the temperature resistance and salt resistance of the polymer filtrate loss additives. Most of the conventional filtrate reducers are applied below 180 ℃, when the bottom hole temperature is higher than 200 ℃, the performance of the filtrate reducers is obviously reduced, the consumption of the filtrate reducers can be increased to meet the requirements, and the drilling cost is increased. The current drilling is usually carried out by using a filtrate reducer Driscal-D, dristemp imported abroad at higher cost.
In the prior art, a Chinese invention patent document with a publication number of CN101691485 and a publication date of 2010, 04 and 07 is proposed, and the technical scheme disclosed in the patent document is as follows: the zwitterionic polymer filtrate reducer has weak salt resistance, and after 2% PAADS is aged in 4% sodium chloride salt water slurry at 200 ℃ at high temperature, FLAPI=65 mL and has larger filtrate loss; in the evaluation of the heat resistance of PAADS, flapi=14.4 mL after 1.5% PAADS has been aged for 16 hours at 200 ℃ did not meet the >220 ℃ requirement.
In summary, the filtrate reducer is an important component of drilling fluid, and at present, three problems mainly exist:
1. the polymer filtrate reducer is easy to degrade, flocculate and desorb when facing to severe environments with the temperature of more than 230 ℃, and the protective capability of clay particles is weakened, so that the performances of drilling fluid such as rheology, filtration, stability and the like are out of control, and the treating agent can not play a role when being invalid.
2. The salt resistance is poor and the drilling requirements cannot be met in certain formations.
3. Some filtrate reducers with better performance are imported and have high cost.
In the prior art, a Chinese patent document with publication number of CN113150754A and publication date of 2021, 07 and 23 is proposed to solve the above technical problems, and the technical scheme disclosed in the patent document is as follows: the invention provides a temperature-resistant and brine-resistant drilling fluid filtrate reducer and a preparation method thereof, wherein the filtrate reducer is prepared by copolymerizing raw materials comprising acrylamide, N-vinyl pyrrolidone, 2-acrylamide-dimethyl propane sulfonic acid and zwitterionic monomers under the action of an initiator.
In the practical use process, the following problems can occur:
in the technical scheme, the raw materials for synthesizing the zwitterionic monomer are complex, the cost is high, the synthesis process is complex, the purification step of the synthesized product is complex, the synthesis yield is low, and industrial production is difficult to carry out.
In the prior art, a Chinese invention patent document with publication number of CN114702632A and publication date of 2022, month 07 and 05 is also proposed to solve the above technical problems, and the technical scheme disclosed in the patent document is as follows: a fluid loss additive for water-base drilling fluid is prepared from monomer containing sulfonate group of water-resistant hydrolytic group, pyridyl group of rigid group, and N, N-dimethyl amide group with better rigidity and heat resistance through copolymerizing monomer and modified carbon point under the action of trigger.
In the practical use process, the following problems can occur:
the modified carbon point is modified by adopting a silane coupling agent KH570, and a rotary evaporator is used for removing the ethanol which is a reaction solvent, so that the ethanol is possibly completely untreated, and the modification is affected; and the ester group connected with C=C double bond on the modified carbon point is greatly influenced by pH and is easy to hydrolyze, so that the action of the modified carbon point is influenced.
Disclosure of Invention
In order to solve the technical problems, the invention provides a nano composite filtrate reducer for a high-temperature-resistant water-based drilling fluid and a preparation method thereof, which can effectively solve the problems of complex preparation process, high cost and easy hydrolysis of modified carbon-point ester groups in the prior art.
The invention is realized by adopting the following technical scheme:
the nano composite filtrate reducer for the high temperature resistant water-based drilling fluid comprises monomers, wherein the monomers comprise acrylamide, N-vinyl pyrrolidone and 2-acrylamide-2-methylpropanesulfonic acid, and the nano composite filtrate reducer is characterized in that: the nano-material also comprises a cationic monomer and nano-material carbon dots; the mass of the carbon dots of the nano material is 1.8-3% of the total mass of the monomer;
the molecular structural formula of the cationic monomer is as follows:
the filtrate reducer is prepared by copolymerization of monomers and nanomaterial carbon dots under the action of an initiator; the chemical structural formula of the filtrate reducer is as follows:
wherein n, m, x, y is a natural number.
The preparation method of the cationic monomer comprises the following steps: triethylamine and 4-vinylbenzyl chloride are used as reaction raw materials, tetrahydrofuran is used as a solvent, water bath is heated to 50 ℃, and reflux reaction is carried out for 12 hours; and then carrying out suction filtration on the reacted mixture to obtain a solid sample, and carrying out vacuum drying at 50 ℃ to obtain the cationic monomer.
The molar ratio of the acrylamide to the 2-acrylamide-2-methylpropanesulfonic acid is 70 (12-20); the molar ratio of the acrylamide to the N-vinyl pyrrolidone is 35 (1-5); the molar ratio of the acrylamide to the cationic monomer is 30 (2-5).
The initiator is an ammonium persulfate and sodium bisulfite oxidation-reduction system; wherein the molar ratio of ammonium persulfate to sodium bisulfite is 1:0.7-1.
The ratio of the total mass of the four monomers and the carbon dots of the nano material to the mass of the ammonium persulfate is 100:0.1-0.7.
A preparation method of a high-temperature-resistant water-based drilling fluid nanocomposite filtrate reducer is characterized by comprising the following steps of: the method comprises the following steps:
S 1 dissolving 2-acrylamido-dimethylpropanesulfonic acid in water;
S 2 go to step S 1 Adding NaOH into the prepared solution to adjust the pH value to 5-9, then adding acrylamide, N-vinyl pyrrolidone and cationic monomer to dissolve, stirring for 15min by using a magnet, adding nano material carbon dots, performing ultrasonic dispersion for 10min, then introducing nitrogen for 20-30 min, and heating at the same time;
S 3 go to step S 2 Adding an initiator into the treated solution, continuously introducing nitrogen, stirring and reacting for 4-9h, extracting a product by using ethanol after the reaction is finished, shearing, granulating, drying and crushing to obtain the high-temperature-resistant water-based drilling fluid nano composite filtrate reducer.
The mass ratio of the total mass of the acrylamide, the 2-acrylamide-dimethyl propane sulfonic acid, the N-vinyl pyrrolidone and the cationic monomer to water is 1 (3-6).
Said step S 2 After the temperature is raised, the temperature is controlled to be 45-65 ℃.
Said step S 3 The particle size of the filtrate reducer prepared in the method is 100-300 meshes.
Compared with the prior art, the invention has the beneficial effects that:
1. compared with the patent document with the publication number of CN113150754A, the cationic monomer synthesized by the invention has a simple structure and does not have a sulfonic acid group; 2-acrylamido-dimethyl propane sulfonic acid monomer contains sulfonic acid group, so that the cationic monomer does not need to introduce sulfonic acid group; the sulfonic acid group is not introduced, so that the synthetic steps of the synthetic monomer are simpler, the cationic monomer can be obtained without purification, and the engineering practice is convenient. Moreover, experiments prove that the cationic monomer does not introduce sulfonic acid groups, has a simpler structure, and has no influence on the performance of the synthesized polymer filtrate reducer.
Compared with the patent document with the publication number of CN114702632A, the nano material carbon dots are not modified, because the nano material carbon dots are provided with hydroxyl, carboxyl and other functional groups, the nano material carbon dots are directly polymerized with monomers, are wrapped in polymer chains through a series of hydrogen bond action and physical acting force, are compounded in a large number of polymer chain-shaped and net-shaped structures of the polymer filtrate reducer, can still keep the morphology and the action after being subjected to deep high-temperature environment, can continuously exert the temperature resistance, and can assist in forming compact and tough thin mud cakes when forming filter cakes, thereby exerting the filtrate reducer performance. The invention does not modify the carbon dots of the nano material, uses the existing material, has wide raw material sources, and can avoid the defect that the silane coupling agent modified ester group is hydrolyzed and cannot exert the function. Compared with modified carbon dots, the fluid loss additive prepared by adopting the nano material carbon dot compounding mode has the advantages that the preparation process is simpler, the addition amount of the nano material carbon dots is increased, and the temperature resistance and the fluid loss reduction performance can be also increased.
In addition, the carbon dot quality of the nano material is greatly improved, the nano material has stronger wrapping effect with the polymer fluid loss additive, more hydrogen bonds and stronger space network structure formed by compounding, so that the apparent viscosity and the plastic viscosity of the drilling fluid can be improved, the capacity of regulating and controlling the rheological property of the drilling fluid by the polymer fluid loss additive is improved, and meanwhile, the fluid loss of the drilling fluid after the viscosity is increased is also reduced.
The invention additionally sets the cationic monomer and the nanomaterial carbon dots, and as the cationic monomer contains benzene ring and quaternary ammonium cations, the rigid structures of the benzene ring and the nanomaterial carbon dots provide temperature resistance for the composite filtrate reducer together, and the benzene ring and the nanomaterial carbon dots act cooperatively; the quaternary ammonium cation and hydroxyl and carboxyl on the carbon dots of the nano material produce adsorption and encapsulation effects, so that the carbon dots of the nano material are inserted into polymer chain links to play the role of the carbon dots. From the aspect of performance, the two are adopted to carry out free radical copolymerization, so that the temperature resistance of the synthesized composite polymer fluid loss additive is improved, and the water-based drilling fluid base slurry also has better rheological property and fluid loss reducing property after being subjected to hot rolling aging at 240 ℃ for 16 hours.
2. In the prior art, for example, the publication number CN113150754 discloses that the preparation of the zwitterionic monomer is divided into 2 steps, the intermediate is obtained by the first step of reaction, the intermediate needs to be purified by column chromatography, the purification process is complex, the target product can be obtained after the second step of reaction, and the target product needs to be stored at 2-8 ℃, and the storage condition requirement is strict. In contrast, the preparation method of the cationic monomer adopted in the invention has simple reaction monomer and reaction process, and the cationic monomer obtained after the reaction is insoluble in the reaction solvent, so that the cationic monomer can be obtained through suction filtration, and a pure reaction product can be obtained through nuclear magnetic analysis without purification, wherein the storage temperature is normal temperature, the storage is convenient, and the method provides a basis for the subsequent synthesis of the filtrate reducer.
3. The invention optimizes the proportion of each component, so that the invention is more suitable for the addition of cationic monomers and nano material carbon dots, has better effect when the nano material carbon dots are copolymerized with other monomers in a composite mode, and improves the integral performance of the filtrate reducer.
4. When the filtrate reducer is prepared, the pH value is adjusted in advance, the rest of monomers and nano material carbon dots are added, and then magnetic stirring and ultrasonic dispersion are utilized, so that the effect of copolymerizing the nano material carbon dots with other monomers in a composite mode is good.
5. The particle size of the filtrate reducer is 100-300 meshes, so that the filtrate reducer is easy to dissolve in water-based drilling fluid base slurry and plays a role.
Drawings
The invention will be described in further detail with reference to the drawings and detailed description, wherein:
FIG. 1 is a nuclear magnetic resonance spectrum of a cationic monomer prepared in the present invention;
FIG. 2 is a TEM image of carbon dots prepared by the hydrothermal method of the present invention;
FIG. 3 is an infrared spectrum of carbon dots prepared by the hydrothermal method of the present invention;
FIG. 4 is a graph showing the morphology of the filtrate reducer prepared in example 3 after drying;
FIG. 5 is a graph of a medium pressure API filter cake of fresh water and brine base slurry with the fluid loss additive prepared in example 3 added at ambient temperature;
FIG. 6 is a graph comparing the medium pressure API filter cakes before and after aging of fresh water base slurries incorporating the fluid loss additives of examples 3 and 4;
FIG. 7 is a high temperature, high pressure filter cake of fresh water base slurry containing the filtrate reducer of example 3;
FIG. 8 is a high temperature, high pressure filter cake of fresh water base slurry containing the filtrate reducer of example 4;
FIG. 9 is a graph comparing the medium pressure API filter cake before and after aging of the brine-based slurry incorporating the fluid loss additives of examples 3 and 4;
FIG. 10 is a graph of the medium pressure API filter cake, the high temperature high pressure filter cake, before and after aging of the fresh water base slurry with the filtrate reducer of example 4;
FIG. 11 is a graph of the medium pressure API filter cake, the high temperature high pressure filter cake before and after aging of a fresh water base slurry with conventional filtrate reducer A added;
FIG. 12 is a graph of the medium pressure API filter cake before and after aging of fresh water base slurry with conventional filtrate reducer B added, the high temperature and high pressure filter cake;
FIG. 13 is a graph of the medium pressure API filter cake, the high temperature high pressure filter cake before and after aging of a fresh water base slurry with conventional filtrate reducer C added;
fig. 14 shows the medium pressure API filter cake, high temperature high pressure filter cake before and after aging of fresh water base slurry with conventional filtrate reducer D added.
Detailed Description
Example 1
The nanomaterial carbon dots for preparing the filtrate reducer of the present invention can be obtained by the following preparation method.
(1) The carbon dots can be synthesized by adopting urea and citric acid by using a microwave reaction method, and the synthesis method refers to ' Yuechen ', the preparation and application of fluorescent composite materials based on the carbon dots [ D ]. The university of Chinese academy of sciences (the institute of optical precision machinery and physics of China academy of sciences), 2020 ', and carbon dot particles with different particle size distribution of 5-10 nm can be prepared by controlling the power of microwave reaction. The specific synthesis method comprises the following steps: weighing 3g of anhydrous citric acid and 6g of urea, pouring into a 100mL beaker, adding 20mL of pure water, placing the beaker with the solution on a magnetic stirrer for stirring and dissolving, placing the beaker with the solution into a microwave oven, heating by microwaves for 5 minutes to obtain a black solid mixture, taking out the beaker, and adding 40mL of pure water to dissolve the solid to obtain a dark brown solution; then placing the solution into a centrifuge tube, centrifuging twice on the centrifuge at 8000r/min for 5min each time, retaining the solution, and removing solids; and finally, sequentially passing the centrifuged solution through a water-based filter membrane with the diameter of 0.45 and a water-based filter membrane with the diameter of 0.22 mu m to finally obtain a carbon dot solution, and finally, obtaining the carbon dot by freeze drying.
(2) The carbon dots can also be prepared by a hydrothermal method: 1.15g of citric acid was weighed and dissolved in 20mL of deionized water and sonicated to dissolve it thoroughly. The prepared solution is transferred into a 30mL hydrothermal reaction kettle with a polytetrafluoroethylene lining, and reacted for 4 hours at 200 ℃ in a muffle furnace. After the reaction is finished, naturally cooling the reaction system to room temperature, and removing supernatant; then 1.5g of sulfanilic acid is weighed and added into the supernatant, the sulfanilic acid is fully dissolved by ultrasonic, and the solution is transferred into a hydrothermal reaction kettle to react for 5 hours at 135 ℃ in a muffle furnace. After the reaction is finished, naturally cooling the reaction system to room temperature again, removing supernatant, sequentially passing through water-based filter membranes of 0.45 and 0.22 mu m to finally obtain carbon dot solution, and finally obtaining carbon dots through freeze drying.
Referring to FIG. 2 of the drawings, it can be seen from FIG. 2 that the particle diameter of carbon dots is 1 to 20nm. Referring to FIG. 3 of the specification, it can be seen from FIG. 3 that the flow rate is 3409cm -1 And 3118cm -1 The telescopic vibration absorption peaks at the positions are respectively corresponding to O-H of hydroxyl and carboxyl on the surface of the carbon dot; 2775cm -1 、2368cm -1 、777cm -1 、596cm -1 And 543cm -1 The telescopic vibration absorption peak at the position corresponds toC-H in the carbon dot; 1720cm -1 And 1624cm -1 The telescopic vibration absorption peak at the position corresponds to c=o in the carbon dot; 1400cm -1 And 1066cm -1 The telescopic vibration absorption peaks at the positions correspond to C-C and C-N in carbon points. According to the infrared data of the carbon point, a plurality of hydroxyl groups and carboxyl groups are available on the carbon point, and the carbon point is mainly formed by C-C and C-N connection, so that mutual identification with a literature can be realized, and the successful synthesis of the carbon point is shown.
Example 2
The cationic monomer for preparing the filtrate reducer is prepared by the following preparation method:
60mL of tetrahydrofuran was weighed into a three-necked flask, 9.91g of triethylamine and 5.0g of 4-vinylbenzyl chloride were added, stirred by a thermostat water bath magnet, oxygen was removed by a three-way device, and the reactant was heated to 50℃and connected to a reflux apparatus for reflux reaction for 12 hours. The reacted mixture was suction filtered, a solid sample was recovered, and the solid product was dried in a vacuum oven at 50 ℃ and stored at 2-8 ℃. The products are subjected to relevant nuclear magnetic hydrogen spectrum test, and the test results refer to figure 1 of the specification. It can be seen that δ7.50, δ7.39 are hydrogen on the benzene ring; delta 6.73, 5.85, 5.32 is hydrogen on vinyl; delta 4.28 and 3.12 are corresponding peaks of several methylene groups on the monomer; δ1.29 is 3 methyl corresponding peaks, demonstrating the success of cationic monomer synthesis.
Example 3
A nano-composite filtrate reducer for high-temperature-resistant water-based drilling fluid and a preparation method thereof. The filtrate reducer comprises 40g of acrylamide, 1.78g of N-vinyl pyrrolidone, 20g of 2-acrylamido-2-methylpropanesulfonic acid, 13.662g of cationic monomer and 1.358g of nanomaterial carbon dots. Wherein the nanomaterial carbon dots were prepared by the hydrothermal method of example 1 above. Wherein the cationic monomer is prepared by the preparation method in the above example 2, and the molecular structural formula of the cationic monomer is as follows:
the chemical structural formula of the filtrate reducer is as follows:
wherein n, m, x, y is a natural number.
The preparation method of the filtrate reducer comprises the following steps: to a four-necked flask equipped with a stirrer, reflux condenser, thermometer and heating device, 301.86g of deionized water and 20g of 2-acrylamido-2-methylpropanesulfonic acid were added; naOH is added to adjust the pH value to 5.0, 40g acrylamide, 1.78-g N-vinyl pyrrolidone and 13.662g cationic monomer are added to dissolve, the mixture is stirred for 15min by a magnet, 1.358g nano material carbon dots are added to carry out ultrasonic dispersion for 10min, nitrogen is added for 20-30 min, and the temperature is raised to 45 ℃. 0.259g of ammonium persulfate was added, 0.118g of sodium hydrogensulfite was added, and the nitrogen was continuously introduced, and after half an hour, the introduction of nitrogen was stopped. The reaction lasts for 4 hours, after 4 hours, the semi-solid polymer is poured into ethanol solution for purification, sheared and granulated, so that the particle size of the filtrate reducer is 100-300 meshes, and then the filtrate reducer is put into a 65 ℃ oven for drying; the yellow powder can be obtained after drying and crushing, and the nano composite filtrate reducer is named as filtrate reducer 1 with specific reference to figure 4 in the specification.
Example 4
A nano-composite filtrate reducer for high-temperature-resistant water-based drilling fluid and a preparation method thereof. The filtrate reducer comprises 30.01g of acrylamide, 6.7g of g N-vinyl pyrrolidone, 25g of 2-acrylamido-2-methylpropanesulfonic acid, 25.604g of cationic monomer and 2.62g of nanomaterial carbon dots. Wherein the nanomaterial carbon dots were prepared by the microwave method described in example 1 above. Wherein the cationic monomer is prepared by the preparation method in the above example 2, and the molecular structural formula of the cationic monomer is as follows:
the chemical structural formula of the filtrate reducer is as follows:
wherein n, m, x, y is a natural number.
The preparation method of the filtrate reducer comprises the following steps: to a four-necked flask equipped with a stirrer, reflux condenser, thermometer and heating device, 349.27g of deionized water and 25g of 2-acrylamido-2-methylpropanesulfonic acid were added; naOH is added to adjust the pH value to 9.0, 30.01g acrylamide, 6.7-g N-vinyl pyrrolidone and 25.604g cationic monomer are added to dissolve, the mixture is stirred for 15min by a magnet, 2.62g nano material carbon dots are added to carry out ultrasonic dispersion for 10min, nitrogen is added for 20-30 min, and the temperature is raised to 65 ℃. 0.2998g of ammonium persulfate was added, 0.1368g of sodium hydrogensulfite was added, and the nitrogen was continuously introduced, and after half an hour, the introduction of nitrogen was stopped. The reaction lasts for 8 hours, after 8 hours, the semi-solid polymer is poured into ethanol solution for purification, sheared and granulated, so that the particle size of the filtrate reducer is 100-300 meshes, and then the filtrate reducer is put into a 65 ℃ oven for drying; and (3) drying and crushing to obtain yellow powder, namely the nano composite filtrate reducer, namely the filtrate reducer 2.
Example 5
A nano-composite filtrate reducer for high-temperature-resistant water-based drilling fluid and a preparation method thereof. The filtrate reducer comprises 37.515g of acrylamide, 5.865g N-vinyl pyrrolidone, 25g of 2-acrylamido-2-methylpropanesulfonic acid, 25.506g of cationic monomer and 2.065g of nanomaterial carbon dots. Wherein the nanomaterial carbon dots were prepared by the microwave method described in example 1 above. Wherein the cationic monomer is prepared by the preparation method in the above example 2, and the molecular structural formula of the cationic monomer is as follows:
the chemical structural formula of the filtrate reducer is as follows:
wherein n, m, x, y is a natural number.
The preparation method of the filtrate reducer comprises the following steps: to a four-necked flask equipped with a stirrer, reflux condenser, thermometer and heating device, 375.54g of deionized water and 25g of 2-acrylamido-2-methylpropanesulfonic acid were added; naOH is added to adjust the pH value to 7.0, 37.515g acrylamide, 5.865g N-vinyl pyrrolidone and 25.506g cationic monomer are added to dissolve, the mixture is stirred for 15min by a magnet, 2.065g nano material carbon dots are added to carry out ultrasonic dispersion for 10min, nitrogen is added for 20-30 min, and the temperature is raised to 55 ℃. 0.322g of ammonium persulfate was added, 0.147g of sodium hydrogensulfite was added, and the nitrogen was continued to be fed, and after half an hour, the feeding of nitrogen was stopped. The reaction lasts for 5 hours, after 5 hours, the semi-solid polymer is poured into ethanol solution for purification, sheared and granulated, so that the particle size of the filtrate reducer is 100-300 meshes, and then the filtrate reducer is put into a 65 ℃ oven for drying; and (3) drying and crushing to obtain yellow powder, namely the nano composite filtrate reducer, namely the filtrate reducer 3.
Performance testing experiments were performed on the fluid loss additives prepared in examples 3, 4 and 5 as follows.
The related performance test method comprises the following steps:
(1) The preparation method of the drilling fluid base slurry comprises the following steps:
4% bentonite slurry preparation: tap water, 4.0% bentonite (mass fraction), 0.2% sodium carbonate (mass fraction), stirring in a slurry cup at 600r/min for 20min by using a low-speed stirrer; stirring at 12000r/min for 10min by using a high-speed stirrer, and then standing for hydration for 16-24h, wherein the product can be used for experiments after hydration for 16 h.
And taking out the pre-hydrated bentonite slurry, placing the bentonite slurry in a low-speed stirrer for stirring, adding the prepared filtrate reducer, stirring the bentonite slurry for 10min by the low-speed stirrer, and stirring the bentonite slurry for 5min at a high speed to obtain the bentonite slurry for evaluation experiments.
15% brine slurry base slurry: tap water, 4.0% bentonite (mass fraction) +0.2% sodium carbonate (mass fraction) +15% sodium chloride (mass fraction), stirring at 600r/min for 20min, transferring into a high stirring cup, stirring at 12000r/min for 10min, and maintaining at room temperature for 16-24h to obtain brine-based slurry.
(2) Detection of routine performance.
Drilling fluidThe rheological property test and the pressure loss test in normal temperature are carried out according to the national standard GB/T16783.1-2014 detection method. Detecting parameters: AV (apparent viscosity), PV (plastic viscosity), YP (dynamic shear force), GEL (static shear force), FL API (Normal temperature Medium pressure fluid loss) FL HTHP (high temperature high pressure fluid loss).
(3) And testing the temperature resistance of the drilling fluid.
The temperature resistance test of the drilling fluid is a high-temperature high-pressure filtration test and a high-temperature hot rolling aging test. According to the national standard GB/T16783.1-2014 detection method, the drilling fluid is detected.
The high-temperature hot rolling aging experimental process comprises the following steps: taking out the drilling fluid after ageing at 240 ℃/16h by hot rolling, and measuring the related performance of the drilling fluid at 30 ℃ after stirring the drilling fluid at a high speed for 10 min.
Rheology and fluid loss of filtrate reducer at normal temperature
Taking two pre-hydrated fresh water base pulps and two pre-hydrated brine base pulps, adding 1wt% of filtrate reducer 1 (the product of example 3) into the fresh water base pulps and the brine base pulps under the condition of continuous stirring, and uniformly stirring at a high speed, wherein the mixture is recorded as filtrate reducer 1 fresh water base pulps and filtrate reducer 1 brine base pulps. Rheological tests and fluid loss tests were performed on fresh water-based slurry, brine-based slurry, fluid loss additive 1 fresh water-based slurry, fluid loss additive 1 brine-based slurry, respectively, and the results are shown in table 1. In Table 1, AV is apparent viscosity, PV is plastic viscosity, YP is dynamic shear force, FL API Refers to the filtration loss of normal temperature and normal pressure drilling fluid.
TABLE 1 rheological properties and fluid loss test table for fluid loss additives at normal temperature
| Experimental pulp | AV(mPa . S) | PV(mPa . S) | YP(Pa) | FL API (mL) |
| Fresh water-based slurry | 8 | 6 | 2 | 45.6 |
| Brine-based slurry | 4 | 3 | 1 | 71.8 |
| Fluid loss additive 1 dilute water-based slurry | 50 | 27 | 23 | 6.5 |
| Fluid loss additive 1 brine-based slurry | 36 | 26 | 10 | 11.6 |
As can be seen from Table 1, the filtrate reducer of the present invention has good filtrate reducing performance with small addition amount, and the formed API medium-pressure filter cake has smooth, thin and compact surface after the filtrate reducer is added, and the specific reference is made to the accompanying figure 5 of the specification.
Rheology and fluid loss of filtrate reducer at high temperature
Three parts of prehydrated fresh water-based slurry, one part is taken as a blank, no filtrate reducer is added, and 1wt% of filtrate reducer 1 (prepared in example 3), filtrate reducer 2 (prepared in example 4) and filtrate reducer 3 (prepared in example 5) are respectively added into the other two parts of fresh water-based slurry under the condition of continuous stirring, and the mixture is stirred uniformly at a high speed and is marked as filtrate reducer 1 fresh water-based slurry, filtrate reducer 2 fresh water-based slurry and filtrate reducer 3 fresh water-based slurry. And respectively carrying out a 240 ℃/16h hot rolling aging experiment on the fresh water base slurry blank, the fluid loss additive 1 fresh water base slurry, the fluid loss additive 2 fresh water base slurry and the fluid loss additive 3 fresh water base slurry, taking out after the experiment, and carrying out rheological property test and fluid loss test, wherein the results are shown in Table 2.
TABLE 2 rheological and fluid loss test tables for fluid loss additives at high temperature
As shown in Table 2, the nano composite filtrate reducer has good filtrate reducing performance after fresh water base slurry and hot rolling aging at 240 ℃, has stable sedimentation performance and good rheological property and filtrate reducing performance after aging for 16 hours at 240 ℃, and shows that the nano composite filtrate reducer can form a compact hydration film, can form a stronger space grid structure on the basis of improving electronegativity of soil particles, improves coalescence stability of the soil particles, and can maintain a better space structure after aging at high temperature, thereby achieving the effect of reducing the filtrate loss. The surface of the high-temperature high-pressure cake formed after aging is smooth and compact, and the specific reference is made to the accompanying drawings 6-8 in the specification.
Rheological property and filtration loss of filtrate reducer under high temperature and high salt
Three parts of pre-hydrated brine-based slurry are taken, one part is taken as a blank sample, no filtrate reducer is added, and 1wt% of filtrate reducer 1 (prepared in example 3) and filtrate reducer 2 (prepared in example 4) and filtrate reducer 3 (prepared in example 5) are respectively added into the other two parts of brine-based slurry under the condition of continuous stirring, and are stirred uniformly at high speed, and are marked as filtrate reducer 1 brine-based slurry, filtrate reducer 2 brine-based slurry and filtrate reducer 3 brine-based slurry. And respectively carrying out 240 ℃/16h hot rolling ageing experiments on a brine base slurry blank, a filtrate reducer 1 brine base slurry, a filtrate reducer 2 brine base slurry and a filtrate reducer 3 brine base slurry, taking out after the experiments, and carrying out rheological property tests and filtrate loss tests, wherein the results are shown in Table 3 and figure 9 of the specification.
TABLE 3 rheological and fluid loss test table for fluid loss additives under high temperature and high salt conditions
As can be seen from Table 3 and the attached drawing 9 in the specification, the filtrate reducer of the invention has good rheological property and filtrate reducing property after being aged for 16 hours at 240 ℃ in brine-based slurry, which proves that the filtrate reducer has good temperature resistance and salt resistance.
Fourth, compared with the performance of the common filtrate reducer at home and abroad
5 parts of fresh water base slurry are taken, 1wt% of filtrate reducer 2 prepared in example 4 and four common filtrate reducers (A, B, C, D) at home and abroad are respectively added into the pre-hydrated fresh water base slurry under the condition of continuous stirring, wherein A, B is acrylamide polymer filtrate reducer, C is nitrile-silicon polymer filtrate reducer, D is sulfonated polymer filtrate reducer, and the mixture is uniformly stirred at a high speed. And respectively carrying out 240 ℃ hot rolling aging experiments on the five fresh water base slurries, and respectively testing rheological properties and fluid loss after aging. The results are shown in Table 4.
TABLE 4 comparison of the performance of the fluid loss additives of the present invention and existing conventional fluid loss additives
As shown in Table 4, compared with 4 other commonly used filtrate reducers at home and abroad, the temperature-resistant salt-resistant nano composite filtrate reducer prepared by the invention is obviously superior to an imported filtrate reducer after aging, has good temperature resistance and good filtrate reducer performance, and can keep good rheological property. Referring to fig. 10 to 14 of the specification, the drawings are respectively real figures of medium-pressure API filter cakes and high-temperature high-pressure filter cakes before and after aging of each experimental slurry.
In a word, the invention adopts self-made novel cationic monomers, simultaneously introduces rigid nanomaterial carbon points, and adopts an aqueous solution free radical polymerization mode to prepare the novel high-temperature-resistant water-based drilling fluid nanocomposite filtrate reducer with common monomers of acrylamide, 2-acrylamide-2-methylpropanesulfonic acid and N-vinyl pyrrolidone. The cationic monomer contains a rigid group benzene ring and a quaternary ammonium cationic group, so that the temperature resistance and salt resistance of the synthetic polymer can be improved; the carbon dots are inorganic nano materials, the nano particles have small particle size and large specific surface area, the surface force, van der Waals force and molecular force are dominant, the interaction between the nano particles or the interaction between the nano particles and a medium becomes more severe, and the unique characteristics are obtained. The carbon dots are used as a rigid plugging material, so that the nano-sized gaps can be effectively plugged, and the instability of drilling fluid flow and a well wall can be prevented. Meanwhile, the nano particles can enhance the structure and the temperature resistance of the clay, and improve the performance of the polymer and the performance of the drilling fluid.
In view of the foregoing, it will be appreciated by those skilled in the art that, after reading the present specification, various other modifications can be made in accordance with the technical scheme and concepts of the present invention without the need for creative mental efforts, and the modifications are within the scope of the present invention.
Claims (8)
1. The preparation raw materials of the high-temperature-resistant water-based drilling fluid nanocomposite filtrate reducer comprise monomers, wherein the monomers comprise acrylamide, N-vinyl pyrrolidone and 2-acrylamide-2-methylpropanesulfonic acid, and the preparation method is characterized in that: the nano-material carbon dots are also included, and the monomer also includes a cationic monomer; the mass of the carbon dots of the nano material is 1.8-3% of the total mass of the monomer; the molar ratio of the acrylamide to the 2-acrylamide-2-methylpropanesulfonic acid is 70 (12-20); the molar ratio of the acrylamide to the N-vinyl pyrrolidone is 35 (1-5); the molar ratio of the acrylamide to the cationic monomer is 30 (2-5);
the molecular structural formula of the cationic monomer is as follows:
the filtrate reducer is prepared by copolymerization of monomers and nanomaterial carbon dots under the action of an initiator; the chemical structural formula of the filtrate reducer is as follows:
wherein n, m, x, y is a natural number.
2. The high temperature resistant water-based drilling fluid nanocomposite filtrate reducer of claim 1, wherein: the preparation method of the cationic monomer comprises the following steps: triethylamine and 4-vinylbenzyl chloride are used as reaction raw materials, tetrahydrofuran is used as a solvent, water bath is heated to 50 ℃, and reflux reaction is carried out for 12 hours; and then carrying out suction filtration on the reacted mixture to obtain a solid sample, and carrying out vacuum drying at 50 ℃ to obtain the cationic monomer.
3. The high temperature resistant water-based drilling fluid nanocomposite filtrate reducer of claim 2, wherein: the initiator is an ammonium persulfate and sodium bisulfite oxidation-reduction system; wherein the molar ratio of ammonium persulfate to sodium bisulfite is 1:0.7-1.
4. The high temperature resistant water-based drilling fluid nanocomposite filtrate reducer of claim 3, wherein: the ratio of the total mass of the four monomers and the carbon dots of the nano material to the mass of the ammonium persulfate is 100:0.1-0.7.
5. A preparation method of a high-temperature-resistant water-based drilling fluid nanocomposite filtrate reducer is characterized by comprising the following steps of: a process for preparing a fluid loss additive according to any one of claims 1 to 4, comprising the steps of:
S 1 dissolving 2-acrylamido-dimethylpropanesulfonic acid in water;
S 2 go to step S 1 Adding NaOH into the prepared solution to adjust the pH value to 5-9, then adding acrylamide, N-vinyl pyrrolidone and cationic monomer to dissolve, stirring for 15min by using a magnet, adding nano material carbon dots, performing ultrasonic dispersion for 10min, then introducing nitrogen for 20-30 min, and heating at the same time;
S 3 go to step S 2 Adding an initiator into the treated solution, continuously introducing nitrogen, stirring and reacting for 4-9h, extracting a product by using ethanol after the reaction is finished, shearing, granulating, drying and crushing to obtain the high-temperature-resistant water-based drilling fluid nano composite filtrate reducer.
6. The method for preparing the high-temperature-resistant water-based drilling fluid nanocomposite filtrate reducer, which is characterized in that: the mass ratio of the total mass of the acrylamide, the 2-acrylamide-dimethyl propane sulfonic acid, the N-vinyl pyrrolidone and the cationic monomer to water is 1 (3-6).
7. The method for preparing the high-temperature-resistant water-based drilling fluid nanocomposite filtrate reducer, which is disclosed in claim 5, is characterized in that: said step S 2 After the temperature is raised, the temperature is controlled to be 45-65 ℃.
8. The method for preparing the high-temperature-resistant water-based drilling fluid nanocomposite filtrate reducer, which is disclosed in claim 5, is characterized in that: said step S 3 The particle size of the filtrate reducer prepared in the method is 100-300 meshes.
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