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CN-122012071-A - Surface treatment method of high-stress fracture-resistant propping agent

CN122012071ACN 122012071 ACN122012071 ACN 122012071ACN-122012071-A

Abstract

The invention relates to the technical field of propping agents, and discloses a surface treatment method of a propping agent for resisting high stress crack, which comprises the following steps of (1) preprocessing a matrix; the invention successfully solves the problems of easy breakage of propping agent, easy falling of coating layer and quick attenuation of flow conductivity in high stress environment through cooperation and cooperative optimization of the steps, adopts quartz sand as a matrix, does not need to depend on expensive bauxite raw materials, has no high-temperature and high-energy consumption steps in the process, has controllable parameters and good repeatability, obviously reduces the production cost and industrialization difficulty, and has the advantages of high stability and long-acting flow conductivity of propping agent, can prolong the effective production period of an oil gas well and provides a solution with technical advancement and economic feasibility for the oil gas exploitation industry.

Inventors

  • GAO WEI
  • ZHAO TING
  • KONG XIANGCHEN

Assignees

  • 太原科技大学

Dates

Publication Date
20260512
Application Date
20260202

Claims (10)

  1. 1. A method for treating the surface of a high stress crack resistant propping agent, which is characterized by comprising the following steps: (1) Pre-treating a substrate, namely soaking a quartz sand substrate with the particle size of 20-40 meshes in 8-10wt% hydrochloric acid solution for 1-2 hours, washing the quartz sand substrate to be neutral by deionized water, and drying the quartz sand substrate at 80-100 ℃; (2) Plasma activation, namely placing the pretreated substrate in plasma treatment equipment, maintaining the vacuum degree in the equipment to be 0.06-0.1MPa, introducing argon and oxygen mixed gas, treating for 10-15min at the power of 150-300W, and introducing hydroxyl and carboxyl active groups on the surface of the substrate; (3) Titanate bonding pretreatment, namely uniformly spraying 5-8wt% of tetrabutyl titanate ethanol solution on the surface of the activated matrix in an atomization spraying mode, wherein the spraying amount is 0.4-0.6mL per gram of matrix, and standing at room temperature for 15-20min to enable tetrabutyl titanate to react with active groups on the surface of the matrix to generate titanate bonds; (4) Preparing an inner layer, namely preparing 25-35wt% of alumina sol, adding 50-100nm of transition metal oxide powder and 0.5-0.8wt% of citric acid dispersing agent into the alumina sol, uniformly stirring the mixture, then injecting the mixture into a high-pressure reaction kettle, putting the mixture into a substrate treated in the step (3), and reacting the substrate for 2-4 hours at 120-150 ℃ and 0.3-0.5MPa to form a compact inner layer; (5) Preparing an outer layer, namely adding 20-30wt% of silica sol prepared in advance into the high-pressure reaction kettle, and maintaining the temperature in the kettle at 90-120 ℃ and the pressure at 0.1-0.2MPa for reacting for 1-2 hours to form a porous outer layer, wherein the mass ratio of the silica in the outer layer is 85-95%; (6) And (3) post-treatment, namely drying the propping agent treated in the step (5) at 80 ℃ for 1h, then drying the propping agent at 110 ℃ for 2h, roasting for 1-2h, introducing mixed gas of hydrogen and nitrogen in the later stage of roasting, preserving heat for 30min, and cooling to room temperature.
  2. 2. The method of claim 1, wherein the argon to oxygen mixing volume ratio in step (2) is 3:1.
  3. 3. The method according to claim 1, wherein the atomization pressure of the atomized spray in step (3) is 0.2-0.3MPa; The ethanol concentration in the tetrabutyl titanate ethanol solution is 70-80vol%.
  4. 4. The method according to claim 1, wherein the alumina sol in the step (4) is prepared from aluminum isopropoxide, nitric acid and deionized water in a molar ratio of 1 (0.1-0.3) (10-20) at 60-80 ℃.
  5. 5. The method according to claim 1, wherein the transition metal oxide in the step (4) is a mixture of zirconium oxide and titanium oxide in a mass ratio of 1:1-3.
  6. 6. The method of claim 1, wherein the mass of alumina in the inner layer in step (4) is 80-90% and the transition metal oxide is doped in an amount of 3-8wt%.
  7. 7. The method of claim 1, wherein the silica sol in step (5) is prepared from ethyl orthosilicate, ethanol and deionized water in a volume ratio of 1 (3-5) (1-2), and the pH value is adjusted to 3-4 during the preparation process.
  8. 8. The method of claim 1, wherein the volume ratio of hydrogen to nitrogen in step (6) is 1:4.
  9. 9. The method according to claim 1, wherein the firing in the step (6) is performed by subsequently programming the temperature to 500-600 ℃ at a temperature increase rate of 5-6 ℃ per minute.
  10. 10. The method of claim 1, wherein the high stress crack resistant proppant inner and outer layers comprise a dual gradient composite metal oxide coating having a total coating thickness of 12-20 μm, an inner layer thickness of 60-70% and an outer layer thickness of 30-40%.

Description

Surface treatment method of high-stress fracture-resistant propping agent Technical Field The invention relates to the technical field of propping agents, in particular to a surface treatment method of a propping agent capable of resisting high stress cracks. Background As oil and gas resource exploitation gradually extends to deep and compact oil and gas reservoirs, hydraulic fracturing technology has become a core means for improving recovery efficiency, and propping agents are used as key materials for maintaining smooth cracks, and the performance of the propping agents directly determines the durability of fracturing effects. The propping agent commonly used in the current industry mainly comprises quartz sand, artificial ceramsite and a tectorial membrane propping agent, but has the defects that the source of the quartz sand propping agent is wide, the cost is low, the natural structure of the quartz sand propping agent is loose, the quartz sand propping agent is easy to break under the high closing pressure of a deep hydrocarbon reservoir, so that cracks are closed and the diversion capability is lost, the artificial ceramsite propping agent mostly uses bauxite as a raw material, the strength is higher, the supply and the demand of bauxite resources are unbalanced, the price is increased, the density of the ceramsite is high, and the pumping difficulty of a fracturing fluid and the operation cost are increased. Therefore, developing a proppant surface treatment method with moderate cost, high compressive strength and excellent diversion capability becomes a key for solving the difficult exploitation problem of deep high-stress oil and gas reservoirs. Disclosure of Invention Aiming at the problems in the prior art, the invention provides a surface treatment method of a high-stress fracture-resistant propping agent. The technical scheme adopted for solving the technical problems is that the surface treatment method of the high-stress crack resistant propping agent comprises the following steps: (1) Pre-treating a substrate, namely soaking a quartz sand substrate with the particle size of 20-40 meshes in 8-10wt% hydrochloric acid solution for 1-2 hours, washing the quartz sand substrate to be neutral by deionized water, and drying the quartz sand substrate at 80-100 ℃; (2) Plasma activation, namely placing the pretreated substrate in plasma treatment equipment, maintaining the vacuum degree in the equipment to be 0.06-0.1MPa, introducing argon and oxygen mixed gas, treating for 10-15min at the power of 150-300W, and introducing hydroxyl and carboxyl active groups on the surface of the substrate; (3) Titanate bonding pretreatment, namely uniformly spraying 5-8wt% of tetrabutyl titanate ethanol solution on the surface of the activated matrix in an atomization spraying mode, wherein the spraying amount is 0.4-0.6mL per gram of matrix, and standing at room temperature for 15-20min to enable tetrabutyl titanate to react with active groups on the surface of the matrix to generate titanate bonds; (4) Preparing an inner layer, namely preparing 25-35wt% of alumina sol, adding 50-100nm of transition metal oxide powder and 0.5-0.8wt% of citric acid dispersing agent into the alumina sol, uniformly stirring the mixture, then injecting the mixture into a high-pressure reaction kettle, putting the mixture into a substrate treated in the step (3), and reacting the substrate for 2-4 hours at 120-150 ℃ and 0.3-0.5MPa to form a compact inner layer; (5) Preparing an outer layer, namely adding 20-30wt% of silica sol prepared in advance into the high-pressure reaction kettle, and maintaining the temperature in the kettle at 90-120 ℃ and the pressure at 0.1-0.2MPa for reacting for 1-2 hours to form a porous outer layer, wherein the mass ratio of the silica in the outer layer is 85-95%; (6) And (3) post-treatment, namely drying the propping agent treated in the step (5) at 80 ℃ for 1h, then drying the propping agent at 110 ℃ for 2h, roasting for 1-2h, introducing mixed gas of hydrogen and nitrogen in the later stage of roasting, preserving heat for 30min, and cooling to room temperature. As a further technical scheme, the mixing volume ratio of argon to oxygen in the step (2) is 3:1. As a further technical scheme, the atomization pressure of the atomization spraying in the step (3) is 0.2-0.3MPa; The ethanol concentration in the tetrabutyl titanate ethanol solution is 70-80vol%. As a further technical scheme, the alumina sol in the step (4) is prepared from aluminum isopropoxide, nitric acid and deionized water according to a molar ratio of 1 (0.1-0.3) (10-20) at 60-80 ℃. As a further technical scheme, the transition metal oxide in the step (4) is a mixture of zirconium oxide and titanium oxide, and the mass ratio of the zirconium oxide to the titanium oxide is 1:1-3. As a further technical scheme, in the step (4), the mass ratio of the aluminum oxide in the inner layer is 80-90%, and the doping amount of the transition metal