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CN-121972229-A - Bentonite-based metal catalyst for viscosity reduction of thick oil while drilling and preparation method and application thereof

CN121972229ACN 121972229 ACN121972229 ACN 121972229ACN-121972229-A

Abstract

The invention provides a bentonite-based metal catalyst for viscosity reduction of thick oil while drilling, and a preparation method and application thereof, and belongs to the field of oilfield chemistry in petroleum industry. The preparation method of the catalyst comprises the steps of hydrating bentonite, dropwise adding a hydrophilic monomer aqueous solution, sequentially adding a reducing agent aqueous solution and an initiator aqueous solution, reacting to obtain a polymer modified bentonite aqueous phase, dropwise adding a first transition metal ligand solution for reacting, and then adding a second transition metal ligand solution for reacting. The catalyst can be used for efficiently catalyzing and cracking thick oil while drilling, so that the high-efficiency viscosity reduction of the thick oil is realized, and meanwhile, the lasting high-efficiency viscosity reduction effect of the thick oil can be maintained. In addition, the catalyst and the drilling fluid have good compatibility, avoid negative influence on the solid wall and the chip carrying capacity of the drilling fluid, and can be integrated into water-based drilling fluid to maintain or enhance the chip carrying efficiency, rheological stability and high-temperature adaptability.

Inventors

  • LI MEICHUN
  • CHENG WENQING
  • ZHONG JIE
  • SUN JINSHENG
  • LV KAIHE

Assignees

  • 中国石油大学(华东)

Dates

Publication Date
20260505
Application Date
20260331

Claims (10)

  1. 1. The preparation method of the bentonite-based metal catalyst for viscosity reduction of thick oil while drilling is characterized by comprising the following steps: (1) Dropwise adding a first transition metal salt aqueous solution into a first water-soluble ligand aqueous solution, reacting, and regulating the pH value to obtain a first transition metal ligand solution; (2) After hydration of bentonite, dropwise adding a hydrophilic monomer aqueous solution, fully and uniformly mixing, sequentially adding a reducer aqueous solution and an initiator aqueous solution, and reacting to obtain a polymer modified bentonite aqueous phase; (3) And then adding a second transition metal ligand solution, reacting, centrifuging, washing and drying to obtain the bentonite-based metal catalyst for reducing viscosity of thick oil while drilling.
  2. 2. The method for preparing a bentonite-based metal catalyst for viscosity reduction of thick oil while drilling according to claim 1, wherein in the step (1), one or more of the following conditions are included: i. The first transition metal salt and the second transition metal salt are respectively and independently selected from one of manganese chloride, nickel chloride, copper chloride, ferric chloride or cobalt chloride; ii. The first water-soluble ligand and the second water-soluble ligand are respectively and independently selected from one of disodium ethylenediamine tetraacetate, citric acid, ethylenediamine di-o-phenylacetic acid, 8-hydroxyquinoline, ethylenediamine, N '-ethylbis (2- [ 2-hydroxyphenyl ] glycine or 2,2' -bipyridine; iii, the mole ratio of the first transition metal salt to the first water-soluble ligand is 0.45-0.9:1, and the mole ratio of the second transition metal salt to the second water-soluble ligand is 0.43-0.85:1; iv the concentration of the first transition metal salt water solution is 0.045-0.09 mol/L, the concentration of the first water-soluble ligand water solution is 0.1-0.5mol/L, the molar concentration of the second transition metal salt water solution is 0.032-0.064mol/L, and the molar concentration of the second water-soluble ligand water solution is 0.05-0.1mol/L.
  3. 3. The method for preparing a bentonite-based metal catalyst for viscosity reduction of thick oil while drilling according to claim 2, wherein in the step (1), one or more of the following conditions are included: i. the first transition metal salt is ferric chloride, nickel chloride or cupric chloride, and the second transition metal salt is manganese chloride or cobalt chloride; ii. The first water-soluble ligand is disodium ethylenediamine tetraacetate, 2 '-bipyridine or ethylenediamine, and the second water-soluble ligand is citric acid or N, N' -ethylbis (2- [ 2-hydroxyphenyl ] glycine.
  4. 4. The method for preparing a bentonite-based metal catalyst for viscosity reduction of thick oil while drilling according to claim 1, wherein in the step (1), one or more of the following conditions are included: i. in the preparation process of the first transition metal ligand solution and the second transition metal ligand solution, the reaction temperature is room temperature, the reaction time is 40-60min, and the reaction is carried out under the stirring condition; ii. The first transition metal salt aqueous solution and the first water-soluble ligand aqueous solution react, then the pH is regulated to 5.5-6.5 to obtain the first transition metal ligand solution, and the second transition metal salt aqueous solution and the second water-soluble ligand aqueous solution react, then the pH is regulated to 6.0-6.8 to obtain the second transition metal ligand solution.
  5. 5. The method for preparing a bentonite-based metal catalyst for viscosity reduction of thick oil while drilling according to claim 1, wherein in the step (2), one or more of the following conditions are included: i. the bentonite is sodium bentonite or calcium bentonite; ii. The bentonite hydration method comprises the steps of adding bentonite into water, and stirring and hydrating at room temperature for 0.5-2 hours, wherein the mass ratio of bentonite to water is 1:5-50; iii, the hydrophilic monomer is one or two of 2-acrylamide-2-methylpropanesulfonic Acid (AMPS) or acrylamide, and the mass concentration of the hydrophilic monomer aqueous solution is 0.067-0.17g/mL; iv, bentonite and hydrophilic monomer in the mass ratio of 1:0.05-1.25.
  6. 6. The method for preparing a bentonite-based metal catalyst for viscosity reduction of thick oil while drilling according to claim 1, wherein in the step (2), one or more of the following conditions are included: i. The initiator is K 2 S 2 O 8 or (NH 4 ) 2 S 2 O 8 ; the mass of the initiator is 8-75wt% of the mass of hydrophilic monomer; the reducing agent is NaHSO 3 or Na 2 S 2 O 5 ; the mass of the reducing agent is 8-75wt% of the mass of hydrophilic monomer; the mass concentration of the aqueous solution of the initiator and the aqueous solution of the reducing agent is 10-50 g/L; ii. The reaction temperature is 40-50 ℃, the reaction time is 2-4h, and the reaction is carried out under the condition of stirring.
  7. 7. The method for preparing a bentonite-based metal catalyst for viscosity reduction of thick oil while drilling according to claim 1, wherein in the step (3), one or more of the following conditions are included: i. The mass ratio of the transition metal salt in the first transition metal ligand solution to the bentonite in the polymer modified bentonite water phase is 1:4.13-82.6, and the mass ratio of the transition metal salt in the second transition metal ligand solution to the bentonite in the polymer modified bentonite water phase is 1:15.87-317.5; ii. The reaction temperature after the first transition metal ligand solution is dripped is room temperature, the reaction time is 40-60min, the reaction is carried out under the stirring condition, the pH value is regulated to 5-6 after the reaction, the reaction temperature after the second transition metal ligand solution is dripped is room temperature, the reaction time is 1-3h, and the reaction is carried out under the stirring condition.
  8. 8. A bentonite-based metal catalyst for viscosity reduction of thick oil while drilling, prepared by the method of any one of claims 1-7.
  9. 9. The use of a bentonite-based metal catalyst for viscosity reduction of thick oil while drilling according to claim 8, as a viscosity reducer while drilling in drilling fluid to achieve viscosity reduction of thick oil.
  10. 10. The use according to claim 9, comprising one or more of the following conditions: i. The mass of the bentonite-based metal catalyst for viscosity reduction of the thick oil while drilling is 0.1-1% of the mass of the drilling fluid; ii. The bentonite-based metal catalyst for reducing viscosity of thick oil while drilling has an applicable temperature range of 130-300 ℃.

Description

Bentonite-based metal catalyst for viscosity reduction of thick oil while drilling and preparation method and application thereof Technical Field The invention belongs to the field of oilfield chemistry in petroleum industry, and particularly relates to a bentonite-based metal catalyst for viscosity reduction of thick oil while drilling, and a preparation method and application thereof. Background Carbonate reservoirs are important hydrocarbon producing formations, however, carbonate reservoir fracture openings develop severely and heavy oil tends to flow into the wellbore along the fracture openings during drilling. Because the density of the thick oil is lower than that of the drilling fluid, the thick oil gradually floats upwards after entering the shaft. Along with gradual reduction of the temperature in the shaft from bottom to top, the floating thick oil can be condensed at the upper part of the shaft, so that the problems of shaft blockage, pipe condensation, drilling sticking and the like are caused, and the safe and efficient development of the thick oil is seriously restricted. In order to solve the problem of stuck thick oil in a shaft, metal ions or metal-based catalysts are generally introduced as viscosity reducers in the prior art. However, the metal catalytic viscosity reducer has the problem of insufficient stability in practical application, and active metals are easy to subside, agglomerate or deactivate in an aqueous phase, so that the catalytic efficiency is difficult to maintain for a long time. Meanwhile, high-valence metal ions easily enter a bentonite interlayer structure and replace original hydration cations in the process of contacting bentonite, so that interlayer hydration capacity is weakened, bentonite expansibility and pulping performance are obviously reduced, and even instability of a drilling fluid system is caused. The catalyst is used for absorbing metal complex by taking bentonite which is a main component of drilling fluid as a carrier, and can lead the catalyst to have better compatibility with the drilling fluid on the basis of catalysis and viscosity reduction, and the baseline rheology and the loss of control of the fluid loss of control of a less disturbance system. In addition, the existing metal viscosity reducer adopts a single metal system, the catalytic path is relatively single, the existing metal viscosity reducer is easily influenced by temperature, salinity and shearing conditions in a complex underground environment, the viscosity reducing duration is limited, and a stable and durable viscosity reducing effect is difficult to realize. For example, patent document CN 110743552A discloses a clay-supported zero-valent metal thick oil thermal cracking catalyst and a preparation method thereof. Dissolving transition metal salt in water, adding polyamine compound, stirring, adding bentonite into transition metal complex, stirring, adding borohydride into the above mixture, filtering, washing with deionized water until no transition metal ion is detected in the first step, oven drying, cooling, and mixing with urea as cocatalyst. The catalyst can reduce the condensation point of thick oil by more than 6 ℃ and the viscosity by more than 50% by catalyzing the hydrothermal cracking of the thick oil. The metal in the residual catalyst in the crude oil after the reaction is less than 1 mug/kg, and the effective rate of the catalyst for repeated use is higher than 90%. The viscosity reducing effect of the thick oil needs to be further improved by taking bentonite which is a main component of the drilling fluid as a carrier, and the viscosity reducing agent adopts a single metal system, has a relatively single catalytic path, is easily influenced by temperature, salinity and shearing conditions in a complex underground environment, has a limited viscosity reducing effect duration, and is difficult to realize a stable and durable viscosity reducing effect. Therefore, there is a need to develop a catalyst material with good compatibility with drilling fluid, multiple catalytic paths, and capable of realizing excellent, stable and durable catalytic viscosity reduction, so as to meet the requirements of high-performance drilling fluid. Disclosure of Invention Aiming at the defects existing in the prior art, the invention provides a bentonite-based metal catalyst for viscosity reduction of thick oil while drilling, and a preparation method and application thereof. The catalyst of the invention gives consideration to the drilling fluid system requirement and the viscous oil viscosity reduction requirement, and has the attribute of 'one-dose-multiple-use'. The catalyst disclosed by the invention can be used for efficiently catalyzing and cracking thick oil while drilling, so that the high-efficiency viscosity reduction of the thick oil is realized, the catalyst can be suitable for the temperature lower than 150 ℃ in a shaft environment, can be suitable for the effective vis