Reservoir modifier for low-permeability sandstone and shale oil reservoirs and preparation method thereof

Abstract

The invention relates to the field of oilfield development, and discloses a reservoir modifier for low-permeability sandstone and shale oil reservoirs and a preparation method of the reservoir modifier. The preparation method comprises the following steps: cleaning, freeze-drying and crushing Chinese usnea to obtain Chinese usnea powder; extracting effective components from the usnea diffracta powder by using a mixed solvent consisting of methanol, water and a first alkaline substance to obtain an extracting solution; mixing the extracting solution with column chromatography silica gel, and recovering methanol through reduced pressure distillation; extracting the silica gel with acid liquor; adding a second alkaline substance, a sulfonating agent, a modifier and water into the acid dissolving solution for reaction, and then adding a surfactant and a stabilizer; and drying and packaging the chemically modified product. Rock is directly dissolved by using the plant extract so as to improve the permeability, and the stratum is not damaged; no strong acid is contained, no harmful substance is generated in the using process, and good environment-friendly benefits are achieved; and the operation is simple, convenient and rapid, and good economic benefits are achieved.

Description

Technical Field

[0001] The invention relates to the field of oil field development, and in particular to a reservoir modifier for low-permeability sandstone and shale oil reservoirs and a preparation method thereof. Background Art

[0002] The existing exploitable reservoirs are mainly low-permeability and ultra-low-permeability. Due to their dense structure and low permeability, the remaining oil is mainly distributed in micron / submicron pores, which are difficult to be effectively affected by existing chemical oil recovery agents. Therefore, the current development method is acidification and fracturing, that is, using chemical substances such as hydrofluoric acid and hydrochloric acid plus pressure sufficient to destroy the formation to artificially create cracks in the formation to increase the permeability. However, the existing technology is very destructive to the formation, and the comprehensive recovery rate is generally still difficult to exceed 15%. In other words, the existing low-permeability reservoir development method is mainly aimed at the problem of low permeability of the formation. Chemical agents (acidifiers), mechanical pressure (fracturing) or combined means are used to artificially create cracks in the formation to increase the permeability of the formation. However, these methods will seriously increase the heterogeneity of the formation, and the residual chemical agents contain toxic and harmful substances and are difficult to handle (such as fluorides), which not only brings difficulties to the subsequent development of the reservoir, but also increases the cost of environmental protection treatment and restricts the development of some reservoirs.

[0003] The current chemical agents for treating low-permeability rock formations mainly use fluoride to corrode silicates under acidification conditions such as hydrochloric acid / sulfuric acid to create dissolution pores. The patents related to oilfield acidification technology are listed below: The invention patent with application number CN202111602520.6 and announcement number CN116333717B discloses a high-viscosity retarder acidifier for acidification of volcanic rock reservoirs, a preparation method and an application thereof. The high-viscosity retarder acidifier is composed of HCl, HF, a polymer thickener, an acidification corrosion inhibitor, an iron ion stabilizer, an acidification demulsifier, a high-viscosity thickener, a hydrating agent and water. It has good temperature resistance, excellent rheological properties at 120°C, good retarding effect and filtration loss reduction effect, can achieve deep penetration of the acid and remove deep formation pollution.

[0004] The invention patent with patent application number CN202211143732.7 and publication number CN117786918A discloses a clay-type shale reservoir acidification transformation design method. The method is based on clay-type shale reservoirs and lithological characteristics, gives full play to the advantages of bedding planes, maintains the rock skeleton, dredges the rock bedding, communicates pores and takes into account large-scale acidification to prevent swelling and washing oil. Quartz, feldspar and clay minerals are used as rock skeletons, and calcite, dolomite, siderite and pyrite in the dissolved bedding are mainly used. A bedding plane acidification transformation injection parameter design method is established, and the part of HCl soluble rock on the dissolved bedding plane is used as the basis for dosage design. The reservoir fracture fracturing is clearly used as the upper limit of the injection pressure, and the injection displacement under this pressure is the upper limit. The overall purpose is to achieve deep treatment of acid, form effective acid etching grooves to improve the permeability of the bedding, and obtain good oil test results of increasing fluid and oil in the field test of shale oil development in the oil field.

[0005] The above acidizing technologies all rely on strong acid and hydrofluoric acid to dissolve rocks, require complex equipment and subsequent treatment, involve harmful substances and environmental issues, and cannot be injected simultaneously with existing oil recovery agents.

[0006] There is currently no research and technology on using plant extracts to corrode silicate rocks. Summary of the invention

[0007] In order to overcome the defects of the prior art, the present invention provides a reservoir modifier for low-permeability sandstone and shale oil reservoirs and a preparation method thereof, and the technical scheme thereof is as follows: A method for preparing a reservoir modifier for low-permeability sandstone and shale oil reservoirs, comprising the following steps: (1) Raw material processing: using usnea as the raw material, washing, freeze-drying and pulverizing are performed in sequence to obtain usnea powder; (2) Methanol extraction: extracting the effective components from the usnea powder obtained in step (1) with a mixed solvent consisting of methanol, water and a first alkaline substance to obtain an extract; wherein the mass ratio of the usnea powder, methanol, water and the first alkaline substance is 20:(100-200):(30-60):(2-10); the first alkaline substance includes one or more of sodium hydroxide, potassium hydroxide, ammonia water, triethylamine, triethanolamine, ethanolamine, diethanolamine and pyridine; (3) Column chromatography silica gel adsorption: the extract obtained in step (2) is mixed with column chromatography silica gel in a mass ratio of 100:(10-20), and then methanol is recovered by vacuum distillation and the product is adsorbed on the silica gel; (4) Acid extraction: extracting the silica gel on which the product was adsorbed in step (3) with an acid solution having a mass concentration of 1 to 5%, so that the product is dissolved in the acid solution to form an acid solution; the acid solution is an aqueous solution of formic acid, acetic acid, citric acid, oxalic acid, hydrochloric acid or sulfuric acid; (5) Chemical modification: adding a second alkaline substance, a sulfonating agent, a modifier and water to the acid solution formed in step (4) to carry out a reaction, and then adding a surfactant and a stabilizer to the reaction product solution to obtain a chemically modified product; wherein the mass ratio of the acid solution, the second alkaline substance, the sulfonating agent, the modifier and water is 100:(2-15):(20-30):(10-20):(50-100); the mass ratio of the reaction product solution, the surfactant and the stabilizer is 100:(5- 10): (3-5); the second alkaline substance includes one of sodium hydroxide, potassium hydroxide and ammonia water; the sulfonating agent includes one of aminosulfonic acid, propane sultone, butane sultone, pyridine sulfur trioxide, butyrolactone, valerolactone, chloroacetic acid and its salts, bromoacetic acid and its salts, and sodium formaldehyde sulfoxylate; the modifier includes one of glutaraldehyde, formaldehyde, hexamethylenetetramine, hydroxymethyl acrylamide, dimethylol urea, dimethylol melamine, trimethylol melamine, dimethylol phenol, and trimethylol phenol; (6) Drying and packaging: The chemically modified product obtained in step (5) is dried and then packaged.

[0008] Furthermore, the extraction temperature in step (2) is 20 to 50° C., and the extraction time is 2 to 6 hours.

[0009] Furthermore, the specification of the column chromatography silica gel in step (3) is 200-400 mesh.

[0010] Furthermore, the acid extraction time in step (4) is 1 to 5 hours.

[0011] Furthermore, the reaction temperature of step (5) is 60 to 100° C., and the reaction time is 6 to 24 hours.

[0012] Furthermore, the stabilizer in step (5) includes one of sodium thiosulfate, sodium bisulfate, sodium sulfite, sodium formaldehyde sulfoxylate, D / L-(iso)ascorbic acid and its salts and esters, gallic acid and its salts and esters, tert-butylhydroquinone, sorbitol, and maltitol.

[0013] Furthermore, the surfactant in step (5) has the following characteristic structure: ; Wherein: Cx is a carbon chain, x=5-18, including alkyl chains with saturated structures, carbon chains with branched structures and carbon chains with cyclic structures, and also including mixed raw material carbon chains extracted from natural oils and petroleum; n=4-18.

[0014] A reservoir modifier for low-permeability sandstone and shale oil reservoirs is prepared according to the above-mentioned preparation method of a reservoir modifier for low-permeability sandstone and shale oil reservoirs.

[0015] The main components of the prepared reservoir modifier have the following typical structures: ; Compared with the prior art, the present invention mainly has the following beneficial technical effects: 1. The present invention utilizes plant extracts to directly dissolve rocks to increase permeability without damaging the strata.

[0016] 2. The reservoir modifier of the present invention does not contain strong acid and does not generate harmful substances during use, thus having good environmental benefits.

[0017] 3. The reservoir modifier of the present invention can be injected synchronously with the oil recovery agent, which is easy and quick to operate and has good economic benefits.

[0018] 4. The present invention has broad application prospects in the development of low-permeability sandstone and shale oil reservoirs.

[0019] In addition, in order to enable those skilled in the art to better understand the present invention, the following example extracts the chemical reaction process (this process is a conventional chemical reaction, and the reaction type and process itself do not involve innovation): . DETAILED DESCRIPTION

[0020] The present invention is described in detail below with reference to the embodiments. Example 1

[0021] 1. Preparation method of reservoir modifier: The mass ratio of usnea powder: methanol: water: ethanolamine is 20:120:30:5, heated at 50°C for 6 hours, the extract is mixed with 400 mesh column chromatography silica gel at a mass ratio of 100:10, the methanol is removed by vacuum distillation, and 1% formic acid is added for extraction. The mass ratio of acid solution, sodium hydroxide, propane sultone, 40% formaldehyde solution, and water is 100:5:20:12:100, the reaction time is 18 hours, and the temperature is 95°C. After the reaction, 5 mass parts of NP-10 and 3 mass parts of sodium D-isoascorbate are added to every 100 mass parts of the reaction solution, dried and packaged.

[0022] 2. Performance characterization results of reservoir modifiers: For sandstone cores with a water permeability of 1.4 mD, the main rock type is quartz. After continuous injection of 0.3% concentration of this product (pH=7.2) at 80°C for 24 hours, the permeability of the sandstone core increased from 1.4 mD to 2.6 mD. Example 2

[0023] 1. Preparation method of reservoir modifier: The mass ratio of usnea powder: methanol: water: diethanolamine: sodium hydroxide is 20:150:40:5:2, heated at 40°C for 3 hours, the extract is mixed with 400 mesh column chromatography silica gel at a mass ratio of 100:15, the methanol is removed by vacuum distillation, and 1% acetic acid is added for extraction. The mass ratio of acid solution, sodium hydroxide, aminosulfonic acid, 40% formaldehyde solution, and water is 100:4:25: 12:100, the reaction time is 12 hours, and the temperature is 85°C. After the reaction, 6 mass parts of OP-7 and 2 mass parts of sodium dithionite are added to every 100 mass parts of the reaction solution, dried and packaged.

[0024] 2. Performance characterization results of reservoir modifiers: For sandstone with water permeability of 5-8mD, the main rock types are quartz and feldspar. After using 0.5% concentration of this product (pH=7.2) and sealing and heating at 100℃ for 72 hours, 2-3μm dissolution cracks and pores are added on the sandstone surface, and the surface roughness Ra increases from 0.6μm to 2.3μm. Example 3

[0025] 1. Preparation method of reservoir modifier: The ratio of usnea powder: methanol: water: 25% ammonia water: triethylamine is 20:180:50:10:3, heated at 35°C for 5 hours, the extract is mixed with 300 mesh column chromatography silica gel at a mass ratio of 100:20, the methanol is removed by vacuum distillation, and 1% citric acid is added for extraction. The mass ratio of acid solution, 25% ammonia water, sodium formaldehyde sulfoxylate, 40% formaldehyde solution, and water is 100:15:30:20:80, the reaction time is 6 hours, and the temperature is 100°C. After the reaction, 10 parts of alkyl polyoxypropylene ether and 5 parts of sorbitol are added to every 100 parts of the reaction solution, dried and packaged.

[0026] 2. Performance characterization results of reservoir modifiers: For sandstone with water permeability of 5-10mD, the main rock types are feldspar and clay. After using 1.5% concentration of this product (pH=7.2) and sealing and heating at 100℃ for 48 hours, 3-4μm dissolution cracks and pores are added on the sandstone surface, and the surface roughness Ra increases from 0.7μm to 3.9μm.

Claims

1. A method for preparing a reservoir modifier for low-permeability sandstone and shale oil reservoirs, characterized in that: The following steps are involved: (1) Raw material processing: using usnea as the raw material, washing, freeze-drying and pulverizing are performed in sequence to obtain usnea powder; (2) Methanol extraction: extracting the effective components from the usnea powder obtained in step (1) with a mixed solvent consisting of methanol, water and a first alkaline substance to obtain an extract; wherein the mass ratio of the usnea powder, methanol, water and the first alkaline substance is 20:(100-200):(30-60):(2-10); the first alkaline substance includes one or more of sodium hydroxide, potassium hydroxide, ammonia water, triethylamine, triethanolamine, ethanolamine, diethanolamine and pyridine; (3) Column chromatography silica gel adsorption: the extract obtained in step (2) is mixed with column chromatography silica gel in a mass ratio of 100:(10-20), and then methanol is recovered by vacuum distillation and the product is adsorbed on the silica gel; (4) Acid extraction: extracting the silica gel on which the product was adsorbed in step (3) with an acid solution having a mass concentration of 1 to 5%, so that the product is dissolved in the acid solution to form an acid solution; the acid solution is an aqueous solution of formic acid, acetic acid, citric acid, oxalic acid, hydrochloric acid or sulfuric acid; (5) Chemical modification: adding a second alkaline substance, a sulfonating agent, a modifier and water to the acid solution formed in step (4) to carry out a reaction, and then adding a surfactant and a stabilizer to the reaction product solution to obtain a chemically modified product; wherein the mass ratio of the acid solution, the second alkaline substance, the sulfonating agent, the modifier and water is 100:(2-15):(20-30):(10-20):(50-100); the mass ratio of the reaction product solution, the surfactant and the stabilizer is 100:(5- 10): (3-5); the second alkaline substance includes one of sodium hydroxide, potassium hydroxide and ammonia water; the sulfonating agent includes one of aminosulfonic acid, propane sultone, butane sultone, pyridine sulfur trioxide, butyrolactone, valerolactone, chloroacetic acid and its salts, bromoacetic acid and its salts, and sodium formaldehyde sulfoxylate; the modifier includes one of glutaraldehyde, formaldehyde, hexamethylenetetramine, hydroxymethyl acrylamide, dimethylol urea, dimethylol melamine, trimethylol melamine, dimethylol phenol, and trimethylol phenol; (6) Drying and packaging: The chemically modified product obtained in step (5) is dried and then packaged.

2. The method for preparing a reservoir modifier for low-permeability sandstone and shale oil reservoirs according to claim 1, characterized in that: The extraction temperature in step (2) is 20 to 50° C., and the extraction time is 2 to 6 hours.

3. The method for preparing a reservoir modifier for low-permeability sandstone and shale oil reservoirs according to claim 1, characterized in that: The specification of the column chromatography silica gel in step (3) is 200-400 mesh.

4. The method for preparing a reservoir modifier for low-permeability sandstone and shale oil reservoirs according to claim 1, characterized in that: The acid extraction time in step (4) is 1 to 5 hours.

5. The method for preparing a reservoir modifier for low-permeability sandstone and shale oil reservoirs according to claim 1, characterized in that: The reaction temperature of step (5) is 60 to 100° C., and the reaction time is 6 to 24 hours.

6. The method for preparing a reservoir modifier for low-permeability sandstone and shale oil reservoirs according to claim 1, characterized in that: The stabilizer in step (5) includes one of sodium thiosulfate, sodium bisulfate, sodium sulfite, sodium formaldehyde sulfoxylate, D / L-(iso)ascorbic acid and its salts and esters, gallic acid and its salts and esters, tert-butylhydroquinone, sorbitol, and maltitol.

7. The method for preparing a reservoir modifier for low-permeability sandstone and shale oil reservoirs according to claim 1, characterized in that: The surfactant in step (5) has the following characteristic structure: ； Wherein: Cx is a carbon chain, x=5-18, including alkyl chains with saturated structures, carbon chains with branched structures and carbon chains with cyclic structures, and also including mixed raw material carbon chains extracted from natural oils and petroleum; n=4-18.

8. A reservoir modifier for low permeability sandstone and shale oil reservoirs, characterized in that: The reservoir modifier is prepared according to the preparation method of a reservoir modifier for low-permeability sandstone and shale oil reservoirs according to any one of claims 1 to 7.

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