A method for increasing production of a high-viscosity oil well

Abstract

The application discloses a high-viscosity oil well stimulation method, and relates to a high-viscosity oil well, thickened oil well development and utilization technology in the field of oil and gas field stimulation reconstruction. The high-viscosity oil well stimulation method comprises the following steps: obtaining reservoir data, including the content of gum bitumen in crude oil components, the viscosity of crude oil and the formation fracture pressure; injecting an organic cleaning agent into the formation under the fracture pressure; injecting acid liquid into the formation to unblock under the fracture pressure, shutting down for 0.5-2 hours; sequentially injecting a crack wall modifier and a synergist into the formation under the fracture pressure, shutting down for 0.5-1 hour; opening the well to flow back and recovering production. The application has reliable principles and simple process, adopts the synergistic effect of multiple schemes such as organic unblocking, inorganic unblocking, crack formation and consolidation modification of main flow channels, forms integrated operation of high-viscosity oil well unblocking, stimulation and long-term effect, solves the problems of high-viscosity oil well plugging damage and low production caused by the deposition of asphaltene components in the process of crude oil exploitation, realizes high-viscosity oil well unblocking, stimulation and the extension of the effective period of stimulation, and has wide application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of high-viscosity oil well development and utilization, and particularly relates to a high-viscosity oil well stimulation method. BACKGROUND

[0002] In the development and production process of an oilfield, due to the complex nature of the formation fluid, some components will be deposited and precipitated to block the oil well pipe and electric pump during the production process due to reasons such as degassing, temperature drop, pressure mutation, irregular agitation, cementing stratum sand production and corrosion products, which causes the electric submersible pump to be stuck, the wellbore to be blocked, the well bottom to be blocked and the like during the production process of the oil well, and thus the oil well cannot be normally produced, and the production capacity is reduced.

[0003] Preliminary statistical analysis shows that the organic components of the blocking materials are mostly asphaltene and long-chain alkane wax, among which asphaltene is the heaviest, most viscous, most complex and most polar component in crude oil. The intermolecular interaction of asphaltene is extremely complex, and has a strong "clustering" tendency, thereby causing deposition to block the wellbore or cause the pump to be stuck, which seriously affects the production and brings great influence to the oilfield production operation. Therefore, how to unblock these blocking materials and increase the unblocking effective period is a problem to be solved in the development process of high-viscosity wells.

[0004] With the rapid development of the world economy, the demand for oil is increasing, the global oil reserves are decreasing, and the trend of crude oil becoming heavier and poorer is obvious. However, the demand for oil has not decreased, and therefore the exploitation of high-viscosity oil is increasingly valued. High-viscosity oil is thick because of high asphaltene content, and currently asphaltene deposition can be treated by physical, chemical and mechanical treatment technologies. The physical method is to maintain the stability of temperature and pressure to avoid sharp drop, low temperature and low pressure. The chemical method is usually to add a dispersant to prevent deposition and to use an aromatic solvent for dissolution treatment. The mechanical treatment method is mechanical stripping, steel wire rope scraping and pipe cleaning. The chemical method is a recognized low-cost, simple process and high-efficiency treatment method. However, these methods have a common characteristic that the unblocking effective period is short and it is difficult to achieve production increase.

[0005] Patent "a catalytic heating auxiliary thickened oil in-situ upgrading method for mining deep heavy oil" (CN202210232284.1), through the hydrothermal cracking reaction of heavy oil to produce non-condensation gas and light hydrocarbon diffusion to the reservoir around, gradually dissolved in heavy oil, so that the viscosity of crude oil is reduced; Patent "ultra-heavy oil recovery method and ultra-heavy oil recovery system" (CN201711284545.X), through the way of mixing thin to realize the viscosity reduction of wellbore; Patent "thickened oil emulsification viscosity reducer, preparation method and thickened oil emulsification viscosity reduction method, application in thickened oil reservoir mining and mining method" (CN201810378210.2), adopt the way of emulsification to realize viscosity reduction; Patent "a method for reducing the viscosity of thickened oil in a thickened oil reservoir and application thereof" (CN202011205673.2), adopt organic solvent to reduce viscosity.

[0006] At present, the research related to high viscosity oil and thickened oil well mostly focuses on how to reduce viscosity, without considering how to make the thickened oil flow into the wellbore more effectively and quickly. The present application provides a high viscosity oil modification method which is integrated with plug removal and yield increase and has a long effective period. SUMMARY

[0007] The present application aims to provide a high viscosity oil well yield increase method which is reliable in principle, simple to operate, integrated with plug removal and yield increase, makes the high viscosity and thickened oil flow into the wellbore quickly, has a long effective period, and solves the problems of pipeline plugging caused by the deposition of asphaltene components in the process of crude oil mining, high viscosity oil well plugging damage and low yield caused by electric pump plugging, etc.

[0008] In order to achieve the above technical purposes, the present application adopts the following technical solutions.

[0009] A high viscosity oil well yield increase method, comprising the following steps in sequence:

[0010] (1) obtaining reservoir data, including the content of gum and asphalt in crude oil components, the viscosity of crude oil and the formation fracture pressure;

[0011] (2) injecting an organic cleaning agent into the formation under the fracture pressure, the organic cleaning agent is composed of the following components by weight: 5-20 parts of demulsifier, 80-95 parts of organic solvent, and the total amount is 100 parts;

[0012] (3) injecting acid liquid into the formation under the fracture pressure to remove the plug, and shutting down for 0.5-2h;

[0013] (4) sequentially injecting a crack wall modifier and a synergist into the formation under the fracture pressure, and shutting down for 0.5-1h;

[0014] The modifier is composed of the following components by weight: 10-20 parts of nano silicon dioxide, 20-30 parts of organic resin, 20-30 parts of organic alcohol, 10-20 parts of ammonium chloride, and the rest is water, and the total amount is 100 parts;

[0015] The synergist is composed of the following components in parts by weight: 5-30 parts of fluorosilane, 20-30 parts of organic alcohol, 10-20 parts of sodium nitrite, and the rest is water, with a total of 100 parts.

[0016] (5) Open well flowback, restore production.

[0017] In step (1), the present application is applicable to the content of colloid pitch of 10-40% or the viscosity of crude oil of 40-3000 mPa·s.

[0018] In step (2), the demulsifier is one or more of ethylene oxide propylene oxide block copolymer ether, polyoxyethylene polyoxypropylene octadecanol ether, and polyoxyethylene polyoxypropylene polyether; the organic solvent is water-soluble organic alcohol, light oil, or a mixture thereof, the organic alcohol is methanol, ethanol, ethylene glycol, or propylene glycol, and the light oil is diesel, kerosene, or low-viscosity crude oil less than 20 mPa·s.

[0019] Further, when the content of colloid pitch is 10-25% or the viscosity is 40-1000 mPa·s, 5-15 parts of demulsifier and 85-95 parts of organic solvent are contained in the organic cleaning agent, the organic solvent is one or more of organic alcohol and light oil; when the content of colloid pitch is 25-40% or the viscosity is 1000-3000 mPa·s, 10-20 parts of demulsifier and 80-90 parts of organic solvent are contained in the organic cleaning agent, and the content of light oil in the organic solvent is greater than or equal to 50%.

[0020] In step (3), the acid liquid is a conventional acid liquid system for reservoir acidification, including: a mud acid system, a fluoroboric acid system, or a retarded mud acid system.

[0021] The mud acid system is 6-15% HCl+1-2% HF+3-6% additive, and the rest is water.

[0022] The fluoroboric acid system is 6-15% HCl+3-6% HBF4+3-6% additive, and the rest is water.

[0023] The retarded mud acid system is 6-15% HCl+2-5% NH4F+3-6% additive, and the rest is water.

[0024] The additive includes conventional acid corrosion inhibitors, iron ion stabilizers, clay stabilizers, surfactants, etc.

[0025] In step (4), the organic resin is one or more of an acrylic resin, tetraethyl orthosilicate, a low-viscosity epoxy resin, a water-based polyurethane resin, a methyl silicone resin, and trimethylsiloxy silicate; the fluorosilane is one or more of heptadecafluorodecyltrimethoxysilane, per(trideca)fluorooctyltriethoxysilane, and perfluorohexadecyltrimethoxysilane; and the organic alcohol is one or more of methanol, ethanol, ethylene glycol, and propylene glycol.

[0026] Organic plugging is prone to occur in the production of high-viscosity oil wells. Currently, the common plugging removal method is organic plugging removal, but the organic matter is prone to rapid deposition and re-plugging after plugging removal. In the production of oil and gas wells, due to the migration of particles, the hydration and expansion of clay, and inorganic scaling, the acidizing plugging removal method is often used, and periodic operations are generally required. Simple matrix acidizing can only remove plugging, and it is difficult to have a good stimulation effect. High-viscosity oil wells are generally loosely cemented, and in the production of heavy oil, inorganic particles are easily carried and accumulated at the bottom of the well. Therefore, the cracks formed by conventional methods are prone to rapid plugging due to the embedding of particles in the wall surface caused by looseness. High-viscosity oil is prone to low-temperature precipitation, and is prone to rapid plugging at low output. Therefore, effective modification measures can be used to improve the single-well output and delay the plugging time of the oil well.

[0027] Compared with conventional plugging removal and stimulation measures, the present application adds a step of injecting a crack wall modifier. According to the self-selection of fluid flow during injection, the fluid flows into cracks, micro-cracks, and large pores. The modifier makes the main flow channels of cracks, micro-cracks, and large pores form hydrophobic and oleophobic flow surfaces, which can effectively improve the stimulation effect of high-viscosity oil wells, prolong the effective period, and have practical value and broad application prospects.

[0028] The present application uses the synergistic effect of multiple schemes of organic plugging removal, inorganic plugging removal, crack formation, and consolidation modification of main flow channels to realize the stimulation of high-viscosity oil wells and prolong the effective period of stimulation. Organic plugging removal can clean the pipelines and equipment, improve the effect of inorganic plugging removal, and provide the basis for stimulation. The synergy of organic plugging removal and inorganic plugging removal can clean the near-wellbore zone, and the cleaning and plugging can provide protection for effective consolidation and modification of main flow channels. The consolidation and modification of main flow channels can not only reduce the damage caused by particle migration and effectively prevent the rapid deposition of high-viscosity oil, but also improve the yield through hydrophobic and oleophobic effects. The multiple synergistic modification method provided by the present application can not only realize the plugging removal and stimulation of high-viscosity oil wells, but also prolong the effective period of stimulation.

[0029] Compared with the prior art, the present application has the following advantages:

[0030] Because the content of colloid and asphalt in high viscosity oil is high, the conventional plugging removal measure is usually in a short effective period after plugging removal because of organic deposition in a short time. The application integrates plugging removal and yield increase, i.e. forming cracks to make high viscosity oil flow into wellbore quickly at the same time of plugging removal, and modifying the flow surface by using hydrophobic and oleophobic modification measures, which makes the organic deposition not form quickly after the completion of construction, thereby effectively prolonging the yield increase modification period. The application solves the problems of pipeline plugging, electric pump plugging caused by the deposition of asphaltene components in the process of crude oil production, and the problems of high viscosity oil well plugging damage and low yield. The application has simple construction process, multiple modification methods are completed in one operation, and the integrated operation of plugging removal, yield increase and long-term effect is realized. Because of long-term effect, the modification frequency is reduced, thereby effectively saving manpower, financial resources and material resources. The application has wide application prospect. DETAILED DESCRIPTION

[0031] The application will be further described below according to examples, so that those skilled in the art can understand the application. It should be clear that the application is not limited in the scope of the specific embodiments, and any changes within the spirit and scope of the application defined and determined by the appended claims are within the protection scope of the application.

[0032] Example 1

[0033] (1) Obtain reservoir data, and take well K-1 as the implementation object. The content of colloid and asphalt in the crude oil of the well is 26%, the viscosity of the crude oil is about 1600 mPa·s, and the fracture pressure is 23 MPa;

[0034] (2) Inject organic cleaning agent A1 into the formation under the fracture pressure, and A1 is composed of 15 parts of epoxy ethane epoxy propylene block copolyether, 35 parts of ethanol and 50 parts of diesel oil by weight;

[0035] (3) Inject acid plugging remover B1 into the formation under the fracture pressure, and shut in for 2 hours;

[0036] B1 is a fluoroboric acid system: 8% HCl+4% HBF4+1% corrosion inhibitor+1% iron ion stabilizer+1% clay stabilizer+1% surfactant;

[0037] (4) Sequentially inject crack wall modifier C1 and synergist D1 into the formation under the fracture pressure, and shut in for 1 hour;

[0038] C1 is composed of 10 parts of nano silicon dioxide, 15 parts of acrylic resin, 15 parts of ethyl silicate, 20 parts of ethanol, 15 parts of ammonium chloride and 25 parts of water by weight;

[0039] D1 is composed of 15 parts of heptadecafluorodecyl trimethoxysilane, 20 parts of ethanol, 15 parts of sodium nitrite and 50 parts of water by weight.

[0040] (5) Open well and flow back, restore production.

[0041] Example 2:

[0042] (1) Obtain reservoir data, take well K-2 as the implementation object, the crude oil in the well contains 17% of colloid pitch, the crude oil viscosity is about 730 mPa·s, and the fracture pressure is 25 MPa;

[0043] (2) Inject organic cleaning agent A2 into the formation below the fracture pressure, A2 is composed of 10 parts of ethylene oxide propylene oxide block copolymer ether, 50 parts of ethanol, and 40 parts of diesel oil by weight;

[0044] (3) Inject acid liquid plugging remover B2 into the formation above the fracture pressure, and shut in for 2 hours;

[0045] B2 is a slow-release mud acid system: 8% HCl + 4% NH4F + 1% corrosion inhibitor + 1% iron ion stabilizer + 1% clay stabilizer + 1% surfactant;

[0046] (4) Sequentially inject fracture wall modifier C2 and synergist D2 into the formation below the fracture pressure, and shut in for 1 hour;

[0047] C2 is composed of 15 parts of nano silicon dioxide, 10 parts of low viscosity epoxy resin, 15 parts of ethyl silicate, 20 parts of ethanol, 15 parts of ammonium chloride, and 25 parts of water by weight;

[0048] D2 is composed of 20 parts of perfluorohexadecyl trimethoxysilane, 20 parts of ethanol, 15 parts of sodium nitrite, and 45 parts of water by weight;

[0049] (5) Open well and flow back, restore production.

[0050] Example 3:

[0051] (1) Obtain reservoir data, take well K-3 as the implementation object, the crude oil in the well contains 30% of colloid pitch, the crude oil viscosity is about 2100 mPa·s, and the fracture pressure is 21 MPa;

[0052] (2) Inject organic cleaning agent A3 into the formation below the fracture pressure, A3 is composed of 20 parts of ethylene oxide propylene oxide block copolymer ether, 30 parts of ethanol, and 50 parts of diesel oil by weight;

[0053] (3) Inject acid liquid plugging remover B3 into the formation above the fracture pressure, and shut in for 2 hours;

[0054] B3 is a fluoroboric acid system: 8% HCl + 6% HBF4 + 1% corrosion inhibitor + 1% iron ion stabilizer + 1% clay stabilizer + 1% surfactant;

[0055] (4) injecting the fracture wall modifier C3 and the synergist D3 into the formation sequentially under the lower fracturing pressure, and shutting in the well for 1 h;

[0056] C3 is composed of 15 parts of nano-silicon dioxide, 10 parts of acrylic resin, 5 parts of low viscosity epoxy resin, 15 parts of ethyl silicate, 20 parts of ethanol, 15 parts of ammonium chloride, and 20 parts of water by weight;

[0057] D3 is composed of 20 parts of heptadecafluorodecyltrimethoxysilane, 30 parts of ethanol, 15 parts of sodium nitrite, and 35 parts of water by weight;

[0058] (5) opening the well to flow back and restoring the production.

[0059] The production conditions of the wells K-1, K-2 and K-3 before the modification are recorded, and the production conditions after the modification are recorded. The data are shown in Table 1.

[0060] Table 1: Modification effect statistics of K-1, K-2 and K-3

[0061]

[0062] The data in Table 1 shows that: (1) the production of the three wells decreases rapidly after the production, which indicates that the high-viscosity oil with high content of colloid bitumen is easy to cause the plugging near the well; (2) the conventional plugging removal measures used in the early stage can effectively remove the plugging near the well, but the maintaining effect is poor, and the production decreases rapidly after the plugging removal, which is similar to the initial production stage; (3) the modification measures provided by the present application have excellent modification effect, and most importantly, the method provided by the present application has good long-term stability.

Claims

1. A method for increasing production in high-viscosity oil wells, comprising the following steps: (1) Obtain reservoir data, including the content of asphalt in crude oil components, crude oil viscosity and formation fracture pressure; (2) Inject an organic cleaning agent into the formation at a pressure below the rupture pressure. The organic cleaning agent is composed of the following components in parts by weight: 5-20 parts of demulsifier, 80-95 parts of organic solvent, and a total of 100 parts. (3) Inject acid into the formation at a pressure higher than the fracturing pressure to unblock the blockage, and shut in the well for 0.5~2 hours; (4) Inject fracture wall modifier and synergist sequentially into the formation below the fracture pressure, and shut in the well for 0.5-1h; the modifier is composed of the following components in parts by weight: 10-20 parts nano silica, 20-30 parts organic resin, 20-30 parts organic alcohol, 10-20 parts ammonium chloride, the remainder being water, with a total of 100 parts; the synergist is composed of the following components in parts by weight: 5-30 parts fluorosilane, 20-30 parts organic alcohol, 10-20 parts sodium nitrite, the remainder being water, with a total of 100 parts; (5) Open the well and return the water to the source to resume production.

2. The method for increasing production in high-viscosity oil wells as described in claim 1, characterized in that, In step (1), the content of asphalt resin is 10 ~ 40% or the viscosity of crude oil is 40 ~ 3000 mPa·s.

3. The method for increasing production in high-viscosity oil wells as described in claim 1, characterized in that, In step (2), the demulsifier is one or more of ethylene oxide-propylene oxide block copolymer ether, polyoxyethylene-polyoxypropylene octadecyl alcohol ether, and polyoxyethylene-polyoxypropylene polyether; the organic solvent is a water-soluble organic alcohol, light oil, or a mixture thereof, wherein the organic alcohol is methanol, ethanol, ethylene glycol, or propylene glycol, and the light oil is diesel, kerosene, or low-viscosity crude oil with a viscosity of less than 20 mPa·s.

4. The method for increasing production in high-viscosity oil wells as described in claim 2, characterized in that, When the content of asphalt resin is 10-25% or the viscosity is 40-1000 mPa·s, the organic cleaning agent contains 5-15 parts of demulsifier and 85-95 parts of organic solvent, wherein the organic solvent is one or more of organic alcohol and light oil; when the content of asphalt resin is 25-40% or the viscosity is 1000-3000 mPa·s, the organic cleaning agent contains 10-20 parts of demulsifier and 80-90 parts of organic solvent, wherein the content of light oil in the organic solvent is greater than or equal to 50%.

5. The method for increasing production in high-viscosity oil wells as described in claim 1, characterized in that, In step (3), the acid solution is a conventional acid solution system for reservoir acidification, including: a soil acid system, a fluoroboric acid system, or a slow-release soil acid system; the soil acid system is 6~15% HCl + 1~2% HF + 3-6% additives, with the remainder being water; the fluoroboric acid system is 6~15% HCl + 3~6% HBF4 + 3-6% additives, with the remainder being water; the slow-release soil acid system is 6~15% HCl + 2~5% NH4F + 3-6% additives, with the remainder being water; the additives include conventional acid corrosion inhibitors, iron ion stabilizers, clay stabilizers, and surfactants.

6. The method for increasing production in high-viscosity oil wells as described in claim 1, characterized in that, In step (4), the organic resin is one or more of acrylic resin, tetraethyl orthosilicate, low viscosity epoxy resin, waterborne polyurethane resin, methyl silicone resin, and trimethylsiloxysilicate; the fluorosilane is one or more of heptadecafluorodecyltrimethoxysilane, per(tetrafluorooctyl)triethoxysilane, and perfluorohexadecyltrimethoxysilane; and the organic alcohol is one or more of methanol, ethanol, ethylene glycol, and propylene glycol.

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