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CN-122014177-A - Method for improving carbon dioxide oil displacement effect

CN122014177ACN 122014177 ACN122014177 ACN 122014177ACN-122014177-A

Abstract

The invention relates to the technical field of oil field development and discloses a method for improving carbon dioxide oil displacement effect, which comprises the following steps of (1) injecting a first composition into an oil reservoir, and then injecting carbon dioxide; the method comprises the steps of (1) injecting a first composition comprising xanthan gum, silicate and an optional first solvent into an oil reservoir, and (2) injecting carbon dioxide into the oil reservoir, wherein the second composition comprises fatty alcohol polyoxyethylene ether sulfate, alkyl hydroxypropyl phosphate betaine, alkyl glycoside, coconut diethanolamide and an optional second solvent. The method can effectively solve the problem of oil extraction rate reduction caused by gas channeling in the oil field. The method can effectively reduce the fluidity of the carbon dioxide gas in the high-permeability area or the crack of the reservoir, and expand the gas flooding range, thereby improving the carbon dioxide flooding effect.

Inventors

  • WANG HAITAO
  • MA TAO
  • LUN ZENGMIN
  • ZHU YANGWEN
  • XIAO PUFU
  • XU GUANLI

Assignees

  • 中国石油化工股份有限公司
  • 中国石油化工股份有限公司石油勘探开发研究院

Dates

Publication Date
20260512
Application Date
20241112

Claims (11)

  1. 1.A method for displacing carbon dioxide, comprising the steps of: (1) Injecting a first composition into the reservoir, followed by injecting carbon dioxide, wherein the first composition comprises xanthan gum, silicate, and optionally a first solvent; (2) And injecting a second composition into the oil reservoir, and then injecting carbon dioxide, wherein the second composition comprises fatty alcohol polyoxyethylene ether sulfate, alkyl hydroxypropyl phosphate betaine, alkyl glycoside, coconut diethanolamide and an optional second solvent.
  2. 2. The process according to claim 1, wherein the weight ratio of xanthan gum to silicate is 1:30-300, preferably 1:33-100; And/or the first solvent is water, wherein the content of the xanthan gum is 0.01-0.3 wt%, preferably 0.05-0.25 wt%, and the content of the silicate is 2-15 wt%, preferably 4-12 wt%, based on the total weight of the first composition; and/or the silicate comprises at least one of sodium silicate, lithium silicate and potassium silicate.
  3. 3. The method of claim 2, wherein the first composition is used in an amount of 0.05-0.3cm 3 and the carbon dioxide is used in an amount of 0.05-0.2cm 3 relative to a reservoir void volume of 1cm 3 .
  4. 4. The method of claim 1, wherein the weight ratio of fatty alcohol polyoxyethylene ether sulfate, alkyl hydroxypropyl phosphate betaine, alkyl glycoside, and coconut diethanolamide is 1:0.01-60:0.008-20, more preferably 1:0.01-0.6:0.01-60:0.008-0.01; And/or the second solvent is water, wherein the fatty alcohol polyoxyethylene ether sulfate is present in an amount of 0.005 to 0.5 wt%, preferably 0.4 to 0.5 wt%, the alkyl hydroxypropyl phosphate betaine is present in an amount of 0.005 to 0.5 wt%, preferably 0.1 to 0.3 wt%, the alkyl glycoside is present in an amount of 0.005 to 0.3 wt%, preferably 0.005 to 0.008 wt%, and the coconut diethanolamide is present in an amount of 0.004 to 0.1 wt%, preferably 0.004 to 0.008 wt%, based on the total weight of the second composition.
  5. 5. The method according to claim 4, wherein the anionic structural formula in the fatty alcohol polyoxyethylene ether sulfate is RO (CH 2 CH 2 O) n SO 3 - , wherein n is 2-3, r is a C8-C18 alkyl group, preferably a C12-C14 alkyl group; and/or the alkyl in the alkyl hydroxypropyl phosphate betaine is a C8-C16 alkyl, preferably a C12-C14 alkyl; and/or the alkyl in the alkyl glycoside is a C8-C16 alkyl, preferably a C8-C14 alkyl.
  6. 6. The method of claim 4 or 5, wherein the second composition is used in an amount of 0.05-0.3cm 3 relative to a reservoir void volume of 1cm 3 .
  7. 7. The method of claim 1, further comprising, prior to step (1), performing step (1-A), injecting montmorillonite-modified rubber into the reservoir, followed by injecting carbon dioxide; Preferably, the preparation method of the montmorillonite modified rubber comprises the following steps: (a) The montmorillonite is hydrated and stripped, then latex is added for mixing, and then drying is carried out; (b) Crushing the dried product, mixing with a cross-linking agent, an accelerator, an activator and an anti-aging agent, plasticating and/or mixing, and vulcanizing; Preferably, the montmorillonite-modified rubber is injected into the reservoir as an aqueous suspension, the concentration of the montmorillonite-modified rubber aqueous suspension being 0.01-10 wt.%; More preferably, the aqueous suspension of montmorillonite modified rubber is used in an amount of 0.05-0.3cm 3 and carbon dioxide is used in an amount of 0.05-0.2cm 3 relative to a reservoir void volume of 1cm 3 .
  8. 8. The process according to claim 7, wherein the montmorillonite has a particle size of 100-500 mesh, preferably 200-300 mesh; and/or the latex has a solids content of 50 to 80 wt.%; and/or the montmorillonite is used in an amount of 1 to 50g, preferably 5 to 40g, per 100g of latex; And/or the hydration stripping is performed under alkaline conditions provided by an alkali metal hydroxide and/or an alkali metal weak acid salt.
  9. 9. A method according to claim 7 or 8, wherein the crushing conditions are such that the particles have a particle size of 20-500 mesh, preferably 50-200 mesh; and/or the cross-linking agent is sulfur, and the dosage of the cross-linking agent is 1-5g, preferably 1-3g, for each 100g of latex; and/or the accelerator is N-cyclohexyl-2-benzothiazole sulfenamide, and the usage amount of the accelerator is 0.2-3g, preferably 0.2-2g, for every 100g latex; And/or the activator comprises a first activator and a second activator, wherein the first activator is stearic acid, the dosage of the first activator is 1-3g, preferably 0.1-2g, for each 100g of latex, the dosage of the second activator is ZnO, and the dosage of the second activator is 1-8g, preferably 1-6g, for each 100g of latex; And/or the anti-aging agent is 2, 4-trimethyl-1, 2-dihydroquinoline polymer, and the amount of the anti-aging agent is 0.2-3g, preferably 0.2-2.5g, for each 100g of latex; and/or the vulcanization conditions include a temperature of 120-155 ℃, preferably 135-150 ℃, and a pressure of 12-18MPa, preferably 14-16MPa.
  10. 10. The method of claim 1, wherein the method of carbon dioxide flooding comprises steps (1-a), (1) and (2) when the width of the fracture of the reservoir is greater than 100 μm; and/or, when the width of the cracks of the oil reservoir is less than or equal to 100 mu m or no cracks are generated, the carbon dioxide flooding method comprises the steps (1) and (2).
  11. 11. Use of the montmorillonite modified rubber according to any one of claims 7-9 in carbon dioxide flooding.

Description

Method for improving carbon dioxide oil displacement effect Technical Field The invention relates to the technical field of oilfield development, in particular to a method for improving a carbon dioxide oil displacement effect. Background With the worldwide emphasis on CO 2 emissions reduction in recent years, more and more CO 2 is being injected or is about to be injected into the ground, and it is desirable to achieve emissions reduction while increasing crude oil recovery. The shortages of gas injection oil displacement are that the density and viscosity difference between CO 2 and crude oil are large, so that the fluidity ratio of CO 2 to crude oil is too large, viscosity fingering and gravity differentiation are easy to generate, the gas sweep volume is affected, and the displacement efficiency is reduced. The main methods for improving the CO 2 oil displacement effect at present are water-gas-drive alternate injection (WAG), foam injection, gel injection and the like. The domestic and foreign practices prove that the foam is one of effective methods for delaying the gas channeling, and the foaming agent is the key for success of the foam surface measures, so that a great deal of research and practice are carried out on the CO 2 foam foaming agent at home and abroad, especially on lignin sulfonate introduced by USP4086964, alpha-olefin sulfonate introduced by USP4393937, CD1045 of Lathanol LAL70 and Chevrn of STEPAN CHEMICAL Co. However, for reservoirs containing fissures and large pore channels, the effectiveness of the foam is greatly reduced. Disclosure of Invention The invention aims to overcome the defects that after carbon dioxide injection is carried out for a certain time in the prior art, a high-permeability area or a crack of an oil reservoir is filled with carbon dioxide, the fluidity of the carbon dioxide in the high-permeability area or the crack is very high, and the carbon dioxide cannot displace crude oil in a larger range, so that the oil extraction rate is reduced. In order to achieve the above object, a first aspect of the present invention provides a method for displacing carbon dioxide, comprising the steps of: (1) Injecting a first composition into the reservoir, followed by injecting carbon dioxide, wherein the first composition comprises xanthan gum, silicate, and optionally a first solvent; (2) And injecting a second composition into the oil reservoir, and then injecting carbon dioxide, wherein the second composition comprises fatty alcohol polyoxyethylene ether sulfate, alkyl hydroxypropyl phosphate betaine, alkyl glycoside, coconut diethanolamide and an optional second solvent. The second aspect of the invention provides application of the montmorillonite modified rubber in carbon dioxide displacement. The method has the beneficial effects that the method can effectively solve the problem of oil extraction rate reduction caused by gas channeling in the oil field. According to the invention, the first composition and the second composition are sequentially injected into the oil reservoir, so that the oil recovery rate of the low-permeability oil reservoir can be effectively improved. Preferably, the montmorillonite modified rubber, the first composition and the second composition are sequentially injected into the oil reservoir, so that the problem of gas channeling in the oil reservoir with cracks and large pore canals can be effectively solved, and the oil recovery rate is improved. The preferred embodiment of the invention can improve the oil extraction rate by more than 16 percent. The method can effectively reduce the fluidity of the carbon dioxide gas in the high-permeability area or the crack of the reservoir, and expand the gas flooding range, thereby improving the carbon dioxide flooding effect. Detailed Description The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein. The first aspect of the invention provides a method for displacing carbon dioxide, which comprises the following steps: (1) Injecting a first composition into the reservoir, followed by injecting carbon dioxide, wherein the first composition comprises xanthan gum, silicate, and optionally a first solvent; (2) And injecting a second composition into the oil reservoir, and then injecting carbon dioxide, wherein the second composition comprises fatty alcohol polyoxyethylene ether sulfate, alkyl hydroxypropyl phosphate betaine, alkyl glycoside, coconut diethanolamide and an optional second solvent. According to the invention, preferably the weight ratio of xanthan gum to silicate is f