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CN-122012139-A - Low-maturity shale oil conversion method based on in-situ electrochemical hydrocracking

CN122012139ACN 122012139 ACN122012139 ACN 122012139ACN-122012139-A

Abstract

The invention belongs to the technical field of oil gas exploitation, and particularly relates to a low-maturity shale oil conversion method based on in-situ electrochemical hydrocracking; by using formation water/injected water as a hydrogen source, a deep reaction bed is constructed through a conductive catalytic fracturing fluid, three-in-one coordination of active hydrogen production by electrolysis, joule heat assistance and catalytic hydrocracking is realized under the action of a direct current electric field, the reaction activation energy is reduced by more than 50%, and the in-situ conversion of low-temperature (< 250 ℃) shale oil with high speed, high quality and low maturity is realized.

Inventors

  • ZHANG WENTONG
  • ZHANG JUNXI
  • JIA QIXIN
  • HUANG HAI
  • SHI JUNTAI
  • XIE TIAN
  • WEI SHIMING
  • WANG YANWEI

Assignees

  • 西安石油大学

Dates

Publication Date
20260512
Application Date
20260403

Claims (10)

  1. 1. The low-maturity shale oil conversion method based on in-situ electrochemical hydrocracking is characterized by comprising the following steps of: S1, constructing a deep conductive catalytic network, namely setting at least two fracturing horizontal wells in a target shale layer section, wherein one well is set as an injection well, and the other well is set as a production well, and forming a communicated slotted network in reservoirs of the two wells through a staged fracturing process; S2, applying an in-situ electric field, namely taking a sleeve of an injection well as an anode, taking the sleeve of a production well or the surface of the side of the production well as a cathode, connecting a high-voltage direct-current power supply, and establishing an electric field on the three-dimensional conductive catalytic network; S3, in-situ hydrocracking reaction, namely enabling formation water endowed in the three-dimensional reaction network to undergo electrochemical reaction by an electric field formed by S2 to generate active hydrogen in situ, wherein the active hydrogen is used as a hydrogen source and undergoes in-situ hydrocracking reaction with cheese roots in low-maturity shale oil in a target shale section to generate light hydrocarbon oil gas reaction products; S4, product displacement and production, namely producing reaction products through the production well.
  2. 2. The conversion method according to claim 1, wherein the bifunctional conductive catalytic fracturing fluid comprises 5-15% of a conductive propping agent, 0.5-3% of a hydrogen evolution-cracking bifunctional catalyst and 1-5% of an electrolyte by mass percent.
  3. 3. The conversion process according to claim 2, wherein the conductive proppant comprises at least any one of nano-graphite powder, multi-walled carbon nanotubes, modified petroleum coke powder, or a combination thereof.
  4. 4. The conversion process according to claim 2, wherein the hydrogen evolution-cleavage bifunctional catalyst comprises at least one of nano molybdenum sulfide or nickel cobalt alloy or a combination thereof.
  5. 5. The conversion process according to claim 2, wherein the electrolyte is a potassium chloride solution or a sodium bicarbonate solution.
  6. 6. The method of claim 1, wherein the applied electric field of S2 results in an effective electric field strength in the formation of 0.5 to 2.0V/cm.
  7. 7. The conversion process of claim 1, wherein the formation temperature at which S3 is reacted is 150-250 ℃.
  8. 8. The transformation method according to claim 1, wherein the time for maintaining the applied electric field at S2 is 3 to 6 months.
  9. 9. The transformation method according to claim 1, wherein S1 the target formation interval is a shale formation with a vitrinite reflectance Ro < 0.7%.
  10. 10. A system for carrying out the conversion process of any one of claims 1-9, comprising: an injection well with a casing as an anode, and a production well with a casing or earth surface as a cathode; the injection device is used for injecting conductive catalytic fracturing fluid into the injection well; The positive and negative output ends of the high-voltage direct current power supply are respectively connected to the injection well and the production well through cables.

Description

Low-maturity shale oil conversion method based on in-situ electrochemical hydrocracking Technical Field The invention belongs to the technical field of oil gas exploitation, and particularly relates to a low-maturity shale oil conversion method based on in-situ electrochemical hydrocracking. Background At present, an in-situ modification technology (ICP) for low-maturity shale oil (Ro < 0.7%) mainly relies on an electric heating rod to carry out simple thermal cracking (Pyrolysis) to generate light oil gas. However, the technology has the following three general defects of high temperature ① and high energy consumption, that is, the shale needs to be heated to 300-500 ℃, the shale has low heat conduction and can be produced after being heated for a plurality of years, the energy return rate (EROI) is extremely low, ② has poor oil quality, coking weight, pure thermal cracking belongs to a dehydrogenation carbonization process, the content of olefin in the product is high and unstable, coke is easy to generate in a stratum, pores are blocked, ③ lacks a hydrogen source, that is, hydrogen is not available underground, hydrogenation upgrading cannot be carried out, and the crude oil has high API gravity and poor fluidity. Thus, there is a need for a low cost, high quality in situ conversion process for low maturity shale oils. Disclosure of Invention Based on the analysis, the application discloses a low-maturity shale oil conversion method based on in-situ electrochemical hydrocracking, which utilizes formation water/injection water as a hydrogen source, constructs a deep reaction bed through a conductive catalytic fracturing fluid, realizes three-in-one coordination of active hydrogen production by electrolysis and joule heat assistance and catalytic hydrocracking under the action of a direct current electric field, reduces the reaction activation energy by more than 50%, and realizes in-situ conversion of low-temperature (< 250 ℃) high-quality low-maturity shale oil. In order to achieve the aim, the technical scheme of the application discloses a low-maturity shale oil conversion method based on in-situ electrochemical hydrocracking, which comprises the following steps of: S1, constructing a deep conductive catalytic network, namely setting at least two fracturing horizontal wells in a target shale layer section, wherein one well is set as an injection well, and the other well is set as a production well, and forming a communicated slotted network in reservoirs of the two wells through a staged fracturing process; S2, applying an in-situ electric field, namely taking a sleeve of an injection well as an anode, taking the sleeve of a production well or the surface of the side of the production well as a cathode, connecting a high-voltage direct-current power supply, and establishing an electric field on the three-dimensional conductive catalytic network; S3, in-situ hydrocracking reaction, namely enabling formation water endowed in the three-dimensional reaction network to undergo electrochemical reaction by an electric field formed by S2 to generate active hydrogen in situ, wherein the active hydrogen is used as a hydrogen source and undergoes in-situ hydrocracking reaction with cheese roots in low-maturity shale oil in a target shale section to generate light hydrocarbon oil gas reaction products; S4, product displacement and production, namely producing reaction products through the production well. Further, the bifunctional conductive catalytic fracturing fluid comprises 5-15% of a conductive propping agent, 0.5-3% of a hydrogen evolution-cracking bifunctional catalyst and 1-5% of an electrolyte by mass percent. Further, the conductive propping agent at least comprises any one of nano graphite powder, multi-wall carbon nano tubes and modified petroleum coke powder or a combination thereof. Further, the hydrogen evolution-cracking bifunctional catalyst at least comprises one or a combination of nano molybdenum sulfide or nickel-cobalt alloy. Further, the electrolyte is potassium chloride solution or sodium bicarbonate solution. Further, the applied electric field in S2 enables the effective electric field intensity formed in the stratum to be 0.5-2.0V/cm. Further, the formation temperature at the time of the reaction described in S3 is 150-250 ℃. Further, the time for maintaining the applied electric field in S2 is 3-6 months. Further, the target stratum segment in S1 is a shale stratum with a specular reflectivity Ro < 0.7%. And, a system for carrying out the above conversion process, comprising: an injection well with a casing as an anode, and a production well with a casing or earth surface as a cathode; the injection device is used for injecting conductive catalytic fracturing fluid into the injection well; The positive and negative output ends of the high-voltage direct current power supply are respectively connected to the injection well and the production well through cables. The beneficial effects ar