Sand consolidation type permeable plugging agent and self-fluxing temporary plugging agent

Abstract

The invention relates to a sand consolidation type permeable plugging agent and a self-fluxing temporary plugging agent, and belongs to the field of oil well sand consolidation. The sand consolidation type permeable plugging agent comprises oil well cement, a self-fluxing temporary plugging agent, a pore generating agent and a reinforcing filler, the self-melting temporary plugging agent is cured at the temperature of 40 DEG C or below and melted at the temperature of 50-90 DEG C; the self-fluxing temporary plugging agent is prepared into particles from the following raw materials in parts by weight: 85-88 parts of thickened oil, 4-5 parts of paraffin, 6-10 parts of epoxy resin and a curing agent, and 2-3 parts of aluminum powder; the pore generating agent is a calcium source compound capable of reacting with aluminum in the self-melting temporary plugging agent to generate gas. According to the sand consolidation type permeable plugging agent and the self-melting temporary plugging agent, the self-melting temporary plugging agent can be melted at the melting temperature, released aluminum powder reacts with the pore generating agent to generate a porous structure, the interior of the plugging agent is communicated, a permeable channel is formed, the permeability is increased while the sand consolidation effect is improved, and normal production of an oil well is facilitated.

Description

TECHNICAL FIELD

[0001] The present application relates to a sand consolidation type permeable plugging agent and a self-melting temporary plugging agent, and belongs to the field of oil well sand consolidation. BACKGROUND

[0002] Sand production in oil wells is one of the problems that oilfield development and exploitation often face, especially in the middle and later stages of oilfield development. Sand production in oil wells is extremely harmful, which may cause serious abrasion of surface and downhole equipment, even sand sticking, leading to a sharp increase in maintenance workload, or even cause oil well shutdown, even cause oil reservoir collapse and damage to casing, and further cause oil well abandonment. These hazards not only increase the production cost of crude oil, but also increase the difficulty of oilfield exploitation. Therefore, in order to prevent sand production in oil wells, appropriate sand control measures need to be taken according to the requirements of the oil reservoir and the exploitation process to ensure normal production of the oil well.

[0003] Mechanical sand control and chemical sand control are the two most common sand control measures. Compared with mechanical sand control, chemical sand control has the advantages of simple process flow, easy follow-up operation and treatment, and is widely used in oil wells. Chemical sand control refers to injecting chemical agents into the sand production layer, so that the loose sand particles near the wellbore are cemented under the adhesive and cementation of the chemical agents, forming a stable artificial well wall with certain strength and permeability, thereby preventing the loose sand particles from falling and migrating, to reduce sand production in oil wells.

[0004] A foam resin sand consolidation type permeable plugging agent is disclosed in Chinese patent application CN117467080A published on January 30, 2014, which comprises a cementing agent, a curing agent, a silane coupling agent, a foaming agent and a foam stabilizer. The main purpose is to modify the melamine formaldehyde resin, introduce a hyperbranched structure, build a three-dimensional network, and improve the compressive performance. The hyperbranched structure also connects the base resin and the silane coupling agent, which can enhance the affinity between the base resin and the sand particles, and further enhance the cementing degree of the base resin. The introduced dopamine has adhesion, which enhances the hydrophilicity of the base resin and also enhances its cementing degree. However, the sand consolidation effect of the sand consolidation type permeable plugging agent is poor in high temperature formation, and the permeability is low, which is not conducive to the production of oil wells after sand consolidation. SUMMARY

[0005] The purpose of the present application is to provide a sand consolidation type permeable plugging agent to solve the problem of poor sand consolidation effect and low permeability of the sand consolidation type permeable plugging agent in the prior art at high temperature.

[0006] The second purpose of the present application is to provide a self-melting temporary plugging agent to meet the use requirements of the sand consolidation type permeable plugging agent.

[0007] In order to achieve the above purposes, the technical scheme adopted by the sand consolidation type permeable plugging agent of the present application is:

[0008] The solid sand type permeable plugging agent comprises oil well cement, self-melting temporary plugging agent, pore forming agent and reinforcing filler; the self-melting temporary plugging agent is solidified below 40 DEG C and melted at 50-90 DEG C; the self-melting temporary plugging agent is made into granular form by the following raw materials: 85-88 parts of thick oil, 4-5 parts of paraffin, 6-10 parts of epoxy resin and curing agent in total, and 2-3 parts of aluminum powder; the pore forming agent is calcium source compound which can react with aluminum in the self-melting temporary plugging agent to generate gas.

[0009] The solid sand type permeable plugging agent realizes plugging to the formation by oil well cement and self-melting temporary plugging agent, wherein the oil well cement can be cemented and adhered with sand particles in the loose soil of the formation, and forms high-strength skeleton after solidification, so that the sand particles cannot migrate; under the action of the temperature of the formation or the warming of hot water in the well flushing process, the self-melting temporary plugging agent melts, releases the aluminum powder wrapped in the self-melting temporary plugging agent, and the aluminum powder reacts with the pore forming agent (such as calcium oxide, calcium hydroxide, etc.) in the water environment to generate hydrogen, to form a connected porous structure and open the solid sand body, thereby forming a permeable channel in the solid sand body. In this way, the sand particles in the formation are cemented and cannot migrate out of the oil well, and the flow of liquid and normal production of the oil well are facilitated.

[0010] In order to further improve the solid sand effect and the permeability of the solid sand body, preferably, the mass ratio of the oil well cement and the self-melting temporary plugging agent is 1:(0.08-0.22), and the mass ratio of the self-melting temporary plugging agent and the pore forming agent is (1-1.2):1; the pore forming agent is composed of calcium oxide and calcium hydroxide in a mass ratio of 3:(1-2). Further preferably, the mass ratio of the oil well cement and the self-melting temporary plugging agent is 1:(0.08-0.15).

[0011] Preferably, the solid sand type permeable plugging agent comprises carbon fiber, and the mass ratio of the oil well cement and the carbon fiber is (60-75):(0.6-0.8). Further preferably, the carbon fiber is mixed by pitch-based carbon fiber and phenolic-based carbon fiber in a mass ratio of 8:(1-2). More preferably, the carbon fiber is short fiber with a length of 0.5-2 mm and a diameter of 5-30 μm.

[0012] Preferably, the reinforcing filler is calcium carbonate, and the mass ratio of the oil well cement and the calcium carbonate is (60-75):(4-21). Further preferably, the mass ratio of the oil well cement and the calcium carbonate is (60-75):(4-13). The addition of calcium carbonate can effectively improve the strength of the solid sand body.

[0013] Preferably, the sand consolidation type permeable plugging agent comprises suspending agent bentonite, retarder ethylenediamine tetramethylene phosphonate sodium, oil well cement, suspending agent, and retarder in a mass ratio of (60-75):(7-18):(0.4-0.8). Further preferably, the oil well cement, suspending agent, and retarder are in a mass ratio of (60-75):(7-12):(0.4-0.5). The addition of bentonite can adjust the suspensibility of the sand consolidation body. The addition of the retarder can adjust the setting time in different formation environments.

[0014] In use, the sand consolidation type permeable plugging agent and water are mixed in a mass ratio of 1:(1-1.2) and then squeezed into the sanding formation.

[0015] The technical scheme of the self-melting temporary plugging agent of the present application is as follows:

[0016] A self-melting temporary plugging agent is made into granular form from the following raw materials by weight: 85-88 parts of thick oil, 4-5 parts of paraffin, 6-10 parts of epoxy resin and curing agent, and 2-3 parts of aluminum powder. The self-melting temporary plugging agent is solidified below 40℃ and melted at 50-90℃.

[0017] The self-melting temporary plugging agent of the present application is an open-type invention. The self-melting temporary plugging agent of the present application is solidified below 40℃ in high-viscosity crude oil and paraffin, the aluminum powder is wrapped therein, the solidified epoxy resin increases the strength, and a solidified body with certain strength is formed. After entering the formation, the self-melting temporary plugging agent can play a role in plugging the dominant channel of the formation. With the increase of temperature, the self-melting temporary plugging agent will melt at a temperature of 50-90℃ to form a flowable liquid, thereby completing the deblocking.

[0018] The present application adds aluminum powder to the self-melting temporary plugging agent. The aluminum powder released from the self-melting temporary plugging agent at high temperature can react with the pore former (such as calcium hydroxide, calcium oxide, and other calcium sources) in the sand consolidation type permeable plugging agent to produce gas, connect the inside of the plugging agent, form a permeable channel, increase the permeability while improving the sand consolidation effect, and facilitate the flow of liquid in the formation and the normal production of the oil well. Paraffin is a forming agent of the self-melting temporary plugging agent, with a melting point of 50-60℃, which is beneficial to the self-deblocking of the self-melting temporary plugging agent at high temperature. After deblocking, the liquid substances such as paraffin and crude oil are squeezed into the deep formation or returned to the ground.

[0019] Preferably, the thick oil has a freezing point of 30-40℃ and a viscosity of 1.0x10 4 -1.50x10 4 mPa·s at 50℃. The thick oil is produced from the Zishan Dong Oil Production Plant, and the solidification temperature is 35℃. The crude oil can change the plugging agent pores to be oil-wet after the self-melting temporary plugging agent is deblocked, which is beneficial to the subsequent oil exploitation and production.

[0020] Preferably, the epoxy resin is E-44, and the curing agent is triethylene tetramine; the mass ratio of the epoxy resin to the curing agent is 5:(0.95-1.05).

[0021] Preferably, the self-melting temporary plugging agent is a microsphere with a diameter of 3-7 mm. The self-melting temporary plugging agent of the present application is formed into a microsphere with a diameter of 3-7 mm. When the curing agent is added, the diameter of the permeable channel formed is large, which is conducive to further improving the permeability after sand consolidation. DETAILED DESCRIPTION

[0022] The technical concept of the present application is to construct a self-melting temporary plugging agent from thickened oil, paraffin, epoxy resin, epoxy resin curing agent and aluminum powder, which presents a cured body with certain strength at room temperature; and melts at a melting temperature of 50-90℃ to release aluminum powder. The aluminum powder can react with the pore-producing components in the sand consolidation type permeable plugging agent to form a permeable channel, thereby improving the sand consolidation effect and increasing the permeability, facilitating the circulation of liquid in the formation and the normal production of the oil well.

[0023] By using other components such as reinforcing agents and short fibers in the sand consolidation type permeable plugging agent, the strength, toughness and pore communication ability of the curing agent can be further optimized, thereby obtaining a sand consolidation type permeable plugging agent with excellent compressive strength and permeability.

[0024] The technical solutions of the present application will be further described below in conjunction with the specific embodiments. The raw materials used in the following examples are all commercially available conventional goods unless otherwise specified. The "%" is the mass percentage unless otherwise specified.

[0025] First, the specific embodiments of the self-melting temporary plugging agent of the present application are as follows:

[0026] Examples 1-7

[0027] The composition and amount of the self-melting temporary plugging agent of each example are shown in Table 1. The viscosity of the crude oil is 1.0x10 4 -1.50x10 4 mPa·s, the epoxy resin E-44 and the curing agent triethylene tetramine are purchased from Wenzhou An'erguxin Material Co., Ltd.

[0028] The preparation method of the self-melting temporary plugging agent in each example uses the following steps: the components are added to an injection molding machine according to the ratio, heated to 80-100℃ on the injection molding machine, stirred uniformly, then injection molded, and cooled to obtain microspheres with a diameter of 3, 5, 7 mm.

[0029] Table 1 Composition of the self-melting temporary plugging agent of Examples 1-7

[0030]

[0031] Secondly, the specific implementation of the sand consolidation type permeability plugging agent is as follows:

[0032] Examples 8-17

[0033] The composition and amount of the sand consolidation type permeability plugging agent in each example are shown in Table 2, wherein the self-fusing temporary plugging agent in the sand consolidation type permeability plugging agent of Examples 8-14 corresponds to the self-fusing temporary plugging agent in Examples 1-7, and the self-fusing temporary plugging agent in the sand consolidation type permeability plugging agent of Examples 15 and 16 is the self-fusing temporary plugging agent of Example 7.

[0034] In Examples 8-16, the calcium source is a mixture of calcium oxide and calcium hydroxide in a mass ratio of 3:1. The short fibers are a mixture of pitch-based carbon fibers and phenolic-based carbon fibers in a mass ratio of 8:2. The length of the short fibers is 0.5-2 mm, and the diameter is 5-30 μm. The use of the above short fibers can increase the strength and toughness of the sand consolidation type permeability plugging agent, and can also strengthen the communication between pores. As a comparison, no short fibers are added in Example 17.

[0035] In use, the sand consolidation type permeability plugging agent of each example in Table 2 is mixed with water in a mass ratio of 1:1.2.

[0036] Table 2 Composition table of the sand consolidation type permeability plugging agent of Examples 8-17

[0037]

[0038]

[0039] Example 18

[0040] The sand consolidation type permeability plugging agent of this example is prepared as follows: 100 g of oil well cement, 8 g of calcium oxide, 12 g of sodium hydroxide, 22 g of the self-fusing temporary plugging agent prepared in Example 2, 28 g of calcium carbonate, 24 g of bentonite, and 1 g of ethylenediamine tetramethylene phosphonate sodium are mixed to prepare a dry agent of the sand consolidation type permeability plugging agent, which is then mixed with 200 g of clean water to obtain a suspension of the sand consolidation type permeability plugging agent.

[0041] In the specific implementation of the sand consolidation type permeability plugging agent of the present application, the following steps are adopted:

[0042] (1) Clean the wellbore, lower the layered tool protection casing, and make preparation for squeezing;

[0043] (2) Squeeze the suspension of the sand consolidation type permeability plugging agent into the wellbore in an amount as designed within the safe pressure range, shut in the well for 36-48 h, and then open the well for production;

[0044] (3) Drilling plug processing wellbore residual sand type permeability plugging agent, hot water cleaning wellbore, accelerate self-melting self-melting temporary plugging agent return;

[0045] (4) Try to squeeze the production water communication pore channel, down the oil pump production formation crude oil.

[0046] III. Comparative Example

[0047] Comparative Example 1

[0048] The sand type permeability plugging agent of the present comparative example is prepared as follows: 40 g of melamine, 0.3 g of dopamine are stirred uniformly to obtain a mixture of melamine and dopamine; the mixture is mixed according to the molar amount of melamine in the mixture and the molar amount of formaldehyde in 37 wt% formaldehyde solution at a ratio of 1:2.5, stirred and heated to 50°C, and kept for 30 min to obtain a modified melamine formaldehyde solution; 0.8 g of ammonium chloride and 0.2 g of γ-aminopropyl triethoxysilane coupling agent are added to 93 g of modified melamine formaldehyde resin solution, stirred uniformly to obtain a first mixture; 0.5 g of sodium dodecyl sulfate and 1 g of carboxymethyl cellulose are added to the first mixture, stirred uniformly to obtain a second mixture, and then the second mixture is foamed through a foam generator with air at a ratio of 1:1.3 by volume to obtain a foam resin sand type permeability plugging agent.

[0049] IV. Experimental Example

[0050] Experimental Example 1

[0051] In this experimental example, the self-melting temporary plugging agent microspheres of Examples 1-7 are placed in a crude oil sample from Pudong Oil Production Plant, and are placed in constant temperature water baths at 50°C, 70°C and 90°C, respectively, and the start melting time and complete melting time are recorded, and the results are shown in Table 3. Among them, the self-melting temporary plugging agent of Example 7 is subjected to three melting experiments at 50°C, 70°C and 90°C, respectively.

[0052] Table 3 Melting of self-melting temporary plugging agent at 50-90°C

[0053] Example Working temperature (°C) Melting start time (min) Melting end time (min) Example 1 50 320 450 Example 2 70 380 490 Example 3 90 390 545 Example 4 50 450 600 Example 5 70 375 510 Example 6 90 410 550 Example 7-1 50 360 540 Example 7-2 70 350 560 Example 7-3 90 410 580

[0054] The self-melting temporary plugging agents of Examples 1-7 above solidify into particles with certain strength below 40°C. As can be seen from the data in Table 3, the self-melting temporary plugging agents of Examples 1-7 begin to melt in crude oil samples at 50-90°C for about 320-450 min, and completely melt completely within 450-600 min.

[0055] Experimental Example 2

[0056] The setting time, compressive strength and permeability of the sand consolidation permeable plugging agent of Examples 8-18 at high temperature were determined, and the compressive strength and permeability of the sand consolidation permeable plugging agent of Comparative Examples 1 and 2 at high temperature were determined, and the results are shown in Table 4.

[0057] In the setting time test, 100 g of quartz sand was measured and filled into a glass tube, water was injected to wet the quartz sand, the sand consolidation permeable plugging agent was injected into the sand mold made of the glass tube, the sand consolidation permeable plugging agent filled the pores of the sand particles, and the initial setting and final setting times of the sand consolidation permeable plugging agent were determined in a constant temperature box at 60°C, 70°C and 90°C, respectively.

[0058] The pore volume of the quartz sand mold was 25±5%, the amount of the plugging agent was 2 times the calculated amount of the test pores, the front end of the plugging agent displaced the water in the pores and was partially mixed with the water, the concentration was reduced, and the plugging agent was collected at the outlet by a collector, the rear end of the plugging agent was retained in the sand mold, and effective plugging was formed. After the simulated plugging agent entered the formation pores, the water in the near-wellbore zone was displaced to the deep part of the formation, the high-concentration plugging agent was retained in the near-wellbore zone, and in actual application, the treatment radius was 2.0-2.5 m.

[0059] The compressive strength was determined as follows: the test sample obtained after 48 h of curing in the constant temperature box was cut to form a core with a diameter of 50 mm and a length of 100 mm, the prepared core was placed in a compressive strength tester, an equal rate load was applied by the testing machine, the relationship curve between the load and displacement was recorded, and the pressure at the time of load drop was obtained.

[0060] The permeability was determined as follows: the prepared core was placed in a permeameter, a pressure of 5 MPa was applied to one end of the core, and the volume and time of the fluid passing through the core were measured to calculate the permeability.

[0061] Table 4 Determination results of the sand consolidation permeable plugging agent of Examples 8-18

[0062] Experimental group Working temperature (°C) Initial setting time (h) Final setting time (h) Compressive strength (MPa) Permeability (mD) Example 8 60 26 47 20 566 Example 9 70 24 40 25 180 Example 10 90 20 42 28 125 Example 11 60 23 40 26 260 Example 12 70 22 42 28 240 Example 13 90 20 45 31 260 Example 14 60 24 46 30 220 Example 15 70 22 42 29 260 Example 16 90 18 40 29 240 Example 17 90 22 42 16 110 Example 18 90 22 40 13.2 760 Comparative Example 1 90 48 90 7.8 2.78

[0063] As shown in Table 4, the sand consolidation permeable plugging agent of Examples 8-16 of the present application began to set at 18-26 h and reached final setting at 40-47 h at 60-90°C. Meanwhile, the broken strength of the solidified body of the sand consolidation permeable plugging agent was high, and the permeability was good, which could well meet the requirements of conventional sand control construction of oil and water wells. The compressive strength and permeability of Examples 17 and 18 were reduced due to the absence of short fibers. In Example 18, the mass ratio of oil well cement to self-fusing temporary plugging agent was 100:22, although the permeability was high, the compressive strength was reduced. The compressive strength of the core of Comparative Example 1 was only 7.8 MPa, the permeability was only 2.78 mD, and the overall sand consolidation effect was poor.

Claims

1. A sand consolidation permeability plug, characterized in that, The oil well cement, self-melting temporary plugging agent, pore forming agent and reinforcing filler; the self-melting temporary plugging agent is solidified below 40 DEG C and melted at 50-90 DEG C; the self-melting temporary plugging agent is made into granular by the following raw materials: thick oil 85-88 parts, paraffin 4-5 parts, epoxy resin and curing agent 6-10 parts in total, aluminum powder 2-3 parts; the pore forming agent is calcium source compound which can react with aluminum in the self-melting temporary plugging agent to generate gas.

2. The sand-consolidating permeability plug of claim 1, wherein, The mass ratio of the oil well cement and the self-melting temporary plugging agent is 1:(0.08-0.22), and the mass ratio of the self-melting temporary plugging agent and the pore forming agent is (1-1.2):1; the pore forming agent is composed of calcium oxide and calcium hydroxide with a mass ratio of 3:(1-2).

3. The sand-fixing permeable plugging agent as described in claim 2, characterized in that, The mass ratio of the oil well cement and the self-melting temporary plugging agent is 1:(0.08-0.15).

4. The sand-consolidating permeability plug of claim 1, wherein the sand-consolidating permeability plug is formed from a mixture of a resin and a particulate material. The sand-fixing permeable plugging agent comprises carbon fiber, and the mass ratio of the oil well cement and the carbon fiber is (60-75):(0.6-0.8).

5. The sand-fixing permeable plugging agent as described in claim 4, characterized in that, The carbon fiber is made by mixing pitch-based carbon fiber and phenolic-based carbon fiber with a mass ratio of 8:(1-2).

6. The sand-consolidating permeability plug of claim 1, wherein, The reinforcing filler is calcium carbonate, and the mass ratio of the oil well cement and the calcium carbonate is (60-75):(4-21).

7. A self-soluble temporary plugging agent, characterized in that, The self-melting temporary plugging agent is made into granular by the following raw materials: thick oil 85-88 parts, paraffin 4-5 parts, epoxy resin and curing agent 6-10 parts in total, aluminum powder 2-3 parts; the self-melting temporary plugging agent is solidified below 40 DEG C and melted at 50-90 DEG C.

8. The self-soluble bridging agent of claim 7, wherein, The solidification point of the thick oil is 30-40℃; the viscosity at 50℃ is 1.0x10 4 -1.50x10 4 mPa-s.

9. The self-soluble bridging agent of claim 7, wherein the at least one bridging agent is selected from the group consisting of guar gum, guar derivatives, cellulose derivatives, polysaccharides, and mixtures thereof. The epoxy resin is epoxy resin E-44, and the curing agent is triethylene tetramine; the mass ratio of the epoxy resin and the curing agent is 5:(0.95-1.05).

10. The self-soluble bridging agent according to any one of claims 7 to 9, wherein the bridging agent is characterized in that, The self-melting temporary plugging agent is microsphere, and the diameter of the microsphere is 3-7 mm.

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