Flexible particle for oil extraction as well as preparation method and application of flexible particle

Abstract

The invention discloses flexible particles for oil extraction and a preparation method and application thereof, and relates to the technical field of oilfield exploitation. The preparation method comprises the following steps: adding a plasticizer and a filler on the basis of a thermoplastic polyester elastomer, mixing, extruding, granulating, adding a dispersant, and emulsifying and dispersing to obtain flexible particles. The prepared flexible particles have good rebound resilience, flexibility and wear resistance, not only can better recover deformation after being pressed so as to adapt to an underground dynamic stress environment, but also can keep flexibility so as to avoid brittle fracture or accumulation of blocked pores when the flexible particles are used for profile control and water plugging, so that the plugging effect is influenced; the flexible particles have good wear resistance to ensure long-term effectiveness thereof. The naphthenic oil and the bisphenol fluorene epoxy resin are adopted as plasticizers and have a synergistic effect on improving the flexibility of the flexible particles.

Description

Technical Field

[0001] The present invention relates to the technical field of oilfield exploitation, and particularly to a flexible particle for oil production, a preparation method thereof and an application thereof. Background Art

[0002] In the later stage of water flooding development in oilfields, the comprehensive water cut rises rapidly, and the remaining oil underground is highly dispersed. Long-term water flooding scouring exacerbates the heterogeneity of the reservoir, large channels appear between oil and water wells, and the injected water circulates ineffectively along the large channels. The difficulty of comprehensive management of water control and oil stabilization is increasing. Profile control and water shutoff is an effective way to improve the heterogeneity of the reservoir by plugging the preferential channels between oil and water wells and improving the water flooding development effect. By using profile control and water shutoff for water control and oil stabilization, the oil recovery rate can be improved.

[0003] At present, the commonly used profile control and water shutoff materials include rigid materials and flexible materials. However, rigid materials have problems such as poor injectability and easy permanent plugging of the bottom layer, while flexible materials can better adapt to the changes in the pore structure of the formation, and can reduce the damage to the bottom layer while achieving effective plugging. Among them, flexible materials include gels, resins, volume-expandable particles, rubbers, etc. Although gels and volume-expandable particles have a certain containment effect on large channels, gel crosslinking is not easy to control and is easily sheared and broken by the formation; the water absorption and swelling rate of volume-expandable particles is too fast, the deformation ability is poor, it is easy to break, and the formation adsorption performance is poor, failing to achieve the expected application effect; resin materials are restricted in their application in profile control and water shutoff due to defects such as poor chemical stability, high cost, and poor environmental protection. Therefore, it is particularly necessary to develop a flexible material with good elasticity, wear resistance and plugging performance for profile control and water shutoff to improve the oil recovery rate.

[0004] Thermoplastic polyester elastomer (TPEE), also known as polyester rubber, is a linear block copolymer composed of a crystalline high-melting-point polyester segment as the hard segment (crystalline phase) and an amorphous polyether or polyester soft segment with a lower glass transition temperature. Among them, the hard segment material is mainly PET or PBT, and the rigidity, polarity and crystallinity of the hardness segment make TPEE have good strength, mechanical properties and thermal stability; the soft segment materials include alcohol ethers such as polyethylene glycol ether and polypropylene glycol ether, or aliphatic polyester compounds such as polycaprolactone and polylactide. The low glass transition temperature and saturation of the soft segment make TPEE have excellent low-temperature resistance, resilience and flexibility. TPEE is mostly used in the preparation of automotive parts, sports shoes, wires and cables, medical devices, rail transit, etc. At present, there is no report on using TPEE as a raw material to prepare a flexible material for profile control and water shutoff to improve the oil recovery rate. Summary of the Invention

[0005] In view of the above-mentioned prior art, the object of the present invention is to provide a flexible particle for oil production, its preparation method and application. The flexible particle of the present invention is prepared by adding a plasticizer and a filler on the basis of a thermoplastic polyester elastomer and under the emulsifying and dispersing action of a dispersant. The flexible particle can not only ensure better recovery of deformation after being compressed to adapt to the downhole dynamic stress environment, but also maintain flexibility to avoid brittle fracture or pore blockage and accumulation when it is used for profile control and water plugging, thereby affecting the plugging effect. The present invention uses naphthenic oil and bisphenol fluorene epoxy resin as plasticizers, which have a synergistic effect in improving the flexibility of the flexible particle.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] In the first aspect of the present invention, there is provided a flexible particle for oil production, comprising the following raw materials in parts by weight:

[0008] 40-70 parts of TPEE, 10-20 parts of plasticizer, 5-15 parts of filler, 2-6 parts of dispersant;

[0009] The plasticizer is a mixture of naphthenic oil and bisphenol fluorene epoxy resin in a mass ratio of (10-15):1.

[0010] In the second aspect of the present invention, there is provided a preparation method of the above flexible particle for oil production, comprising the following steps:

[0011] (1) After preheating TPEE, the plasticizer and the filler are added in sequence, and after mixing, a mixed rubber is obtained; the mixed rubber is extruded and granulated to obtain preformed particles;

[0012] (2) The preformed particles are added to the dispersant solution, stirred for emulsifying and dispersing, and after cooling, filtered, washed and dried to obtain the flexible particle for oil production.

[0013] Preferably, in step (1), the preheating temperature is 120-150 °C and the preheating time is 5-10 min.

[0014] Preferably, in step (1), the mixing temperature is 130-160 °C and the mixing time is 10-20 min.

[0015] Preferably, in step (1), the extrusion granulation temperature is 120-150 °C.

[0016] Preferably, in step (1), the particle size of the preformed particles is 1-10 mm.

[0017] Preferably, in step (2), the dispersant solution is a mixture of a dispersant and water, and its mass concentration is 2%-5%.

[0018] Preferably, in step (2), the stirring speed is 800 - 1500 rpm and the stirring time is 10 - 20 min.

[0019] In the third aspect of the present invention, an application of the above flexible particles for oil production in oilfield development is provided.

[0020] Advantages of the present invention:

[0021] The present invention uses thermoplastic polyester elastomer (TPEE) as the matrix, adds naphthenic oil and bisphenol fluorene epoxy resin as plasticizers, calcium carbonate or talcum powder as fillers, and Tween - 80 as a dispersant. The flexible particles for oil production prepared have good flexibility, elasticity, wear resistance and plugging performance.

[0022] TPEE as the matrix material provides the main structure and mechanical properties for the flexible particles. Naphthenic oil and bisphenol fluorene epoxy resin as plasticizers can penetrate between the molecular chains of TPEE, weaken the intermolecular force, and lower the glass transition temperature of the material, thereby improving the flexibility of the flexible material. This enables the flexible material to maintain flexibility during profile control and water plugging, avoiding brittle fracture or pore blockage and accumulation. At the same time, the combination of bisphenol fluorene epoxy resin and naphthenic oil as plasticizers has a synergistic effect in improving the flexibility of the flexible material. Talcum powder / calcium carbonate as fillers, the surface - treated fillers can enhance the compatibility with TPEE and optimize the wear resistance of the material. Tween - 80 as a dispersant, its hydrophilic - lipophilic structure bridges the polar fillers (fillers) and the non - polar or weakly polar matrix, enhancing the interfacial bonding force. At the same time, it can also reduce the surface energy of the plasticizer and filler, thereby promoting their uniform distribution in the TPEE matrix, avoiding agglomeration, and ensuring the uniformity of the performance of the prepared flexible material.

[0023] In summary, by adding plasticizers and fillers to modify TPEE, the flexible material can better recover its deformation after being compressed, thus adapting to the downhole dynamic stress environment. It can also prevent the flexible material from deforming and ensure its long - term effectiveness during the process of profile control and water plugging. It can be seen that the present invention selects TPEE, plasticizers, fillers and dispersants as raw materials, and the prepared flexible material achieves both the balance of flexibility and elasticity and the synergy of wear resistance and plugging. When used for profile control and plugging, its viscoelasticity enables it to enter the formation pores through deformation during injection and then achieve plugging by elastic recovery, thereby realizing the oil recovery rate of profile control and water plugging. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 : Pictures of flexible particles for oil production with different particle sizes prepared in Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] It should be noted that the following detailed description is illustrative and aims to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0026] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in conjunction with specific embodiments.

[0027] The experimental materials used in the embodiments of the present invention are all conventional experimental materials in the art and can be obtained through commercial channels.

[0028] Among them, TPEE is purchased from Keheng High Polymer (Guangdong) Co., Ltd., and bisphenol fluorene epoxy resin is purchased from Shandong Suihua Biotechnology Co., Ltd., and the product name is epoxy group bisphenol fluorene.

[0029] Example 1: Flexible particles for oil production

[0030] The flexible particles for oil production are prepared by mixing TPEE, plasticizer, filler and dispersant according to a weight ratio of 55:15:10:4.

[0031] Among them, the plasticizer is a mixture of naphthenic oil and bisphenol fluorene epoxy resin according to a mass ratio of 12:1, the filler is talcum powder with a particle size of 700 mesh, and the dispersant is Tween-80.

[0032] The specific preparation method is as follows:

[0033] (1) Preheat TPEE at 135 °C for 8 min, then sequentially add the plasticizer and filler to the preheated TPEE. After mixing evenly, knead at 145 °C for 15 min to obtain a kneaded rubber; extrude and pelletize the kneaded rubber at 135 °C to obtain preformed particles with a particle size of 1 mm;

[0034] (2) Mix the dispersant and water to prepare a dispersant solution with a mass fraction of 3.5%; add the preformed particles to the dispersant solution and stir at 1200 rpm for 15 min for emulsification and dispersion. After the dispersion is completed, cool to room temperature, filter, wash and dry to obtain the flexible particles for oil production.

[0035] Example 2: Flexible particles for oil production

[0036] The flexible particles for oil production are prepared by mixing TPEE, plasticizer, filler and dispersant according to a weight ratio of 40:10:5:2. The plasticizer is a mixture of naphthenic oil and bisphenol fluorene epoxy resin according to a mass ratio of 10:1, the filler is talcum powder with a particle size of 600 mesh, and the dispersant is Tween-80.

[0037] The specific preparation method is as follows:

[0038] (1) Place the TPEE at 120 °C for preheating for 10 min, then successively add the plasticizer and filler to the preheated TPEE. After mixing evenly, place it at 130 °C for kneading for 10 min to obtain a kneaded rubber; extrude and pelletize the kneaded rubber at 120 °C to obtain preformed pellets with a particle size of 5 mm;

[0039] (2) Mix the dispersant and water to prepare a dispersant solution with a mass fraction of 3%; add the preformed pellets to the dispersant solution, stir at 800 rpm for 15 min for emulsification and dispersion, cool to room temperature after the dispersion is completed, filter, wash, and dry to obtain the flexible particles for oil production.

[0040] Example 3: Flexible particles for oil production

[0041] The flexible particles for oil production are prepared by mixing TPEE, plasticizer, filler, and dispersant according to a weight ratio of 70:30:15:6. The plasticizer is a mixture of naphthenic oil and bisphenol fluorene epoxy resin in a mass ratio of 15:1, the filler is talcum powder with a particle size of 600 mesh, and the dispersant is Tween-80.

[0042] The specific preparation method is as follows:

[0043] (1) Place the TPEE at 150 °C for preheating for 5 min, then successively add the plasticizer and filler to the preheated TPEE. After mixing evenly, place it at 160 °C for kneading for 20 min to obtain a kneaded rubber; extrude and pelletize the kneaded rubber at 150 °C to obtain preformed pellets with a particle size of 5 - 10 mm;

[0044] (2) Mix the dispersant and water to prepare a dispersant solution with a mass fraction of 5%; add the preformed pellets to the dispersant solution, stir at 1500 rpm for 15 min for emulsification and dispersion, cool to room temperature after the dispersion is completed, filter, wash, and dry to obtain the flexible particles for oil production.

[0045] Comparative Example 1:

[0046] The difference between this comparative example and Example 1 is that TPEE is replaced by SEBS (styrene - ethylene - butene - styrene lead - acid copolymer).

[0047] The flexible particles for oil production are prepared by mixing SEBS, plasticizer, filler, and dispersant according to a weight ratio of 55:15:10:4.

[0048] Among them, the plasticizer is a mixture of naphthenic oil and bisphenol fluorene epoxy resin in a mass ratio of 12:1, the filler is talcum powder with a particle size of 700 mesh, and the dispersant is Tween-80.

[0049] The specific preparation method is as follows:

[0050] (1) Preheat SEBS at 135°C for 8 min, then successively add a plasticizer and a filler to the preheated SEBS. After mixing evenly, knead at 145°C for 15 min to obtain a kneaded rubber. Extrude and pelletize the kneaded rubber at 135°C to obtain preformed pellets with a particle size of 1 mm;

[0051] (2) Mix a dispersant and water to prepare a dispersant solution with a mass fraction of 3.5%. Add the preformed pellets to the dispersant solution and stir at 1200 rpm for 15 min for emulsification and dispersion. After the dispersion is completed, cool to room temperature, filter, wash, and dry to obtain flexible particles for oil production.

[0052] Comparative Example 2:

[0053] The difference between this comparative example and Example 1 is that no plasticizer is added when preparing the flexible particles.

[0054] In this comparative example, the flexible particles are prepared by mixing TPEE, a filler, and a dispersant in a weight ratio of 55:10:4. The dispersant is Tween-80.

[0055] The specific preparation method is as follows:

[0056] (1) Preheat TPEE at 135°C for 8 min, then add a filler to the preheated TPEE. After mixing evenly, knead at 145°C for 15 min to obtain a kneaded rubber. Extrude and pelletize the kneaded rubber at 135°C to obtain preformed pellets with a particle size of 1 mm;

[0057] (2) Mix a dispersant and water to prepare a dispersant solution with a mass fraction of 3.5%. Add the preformed pellets to the dispersant solution and stir at 1200 rpm for 15 min for emulsification and dispersion. After the dispersion is completed, cool to room temperature, filter, wash, and dry to obtain the flexible particles.

[0058] Comparative Example 3:

[0059] The difference between this comparative example and Example 1 is that the plasticizer is only naphthenic oil.

[0060] The flexible particles for oil production are prepared by mixing TPEE, a plasticizer, a filler, and a dispersant in a weight ratio of 55:15:10:4. Among them, the plasticizer is naphthenic oil, the filler is talc powder with a particle size of 700 mesh, and the dispersant is Tween-80. The preparation method of the flexible particles is the same as that of Example 1.

[0061] Comparative Example 4:

[0062] The difference between this comparative example and Example 1 is that the plasticizer is only bisphenol fluorene epoxy resin.

[0063] The flexible particles for oil production are prepared by mixing TPEE, plasticizer, filler and dispersant according to a weight ratio of 55:15:10:4. Among them, the plasticizer is bisphenol fluorene epoxy resin, the filler is talcum powder with a particle size of 700 mesh, and the dispersant is Tween-80. The preparation method of the flexible particles is the same as that of Example 1.

[0064] Test example:

[0065] The properties of the flexible particles with a particle size of 2 mm prepared in Example 1 and Comparative Examples 1-4 were detected as follows:

[0066] 1. Plugging performance

[0067] The flexible particles prepared in Example 1 and Comparative Examples 1-3 were respectively configured into a 5 wt% suspension with oilfield reinjection sewage, and then a single-core simulation experiment of the core was carried out. Among them, the specifications of the single-core of the core were a core with a diameter of 2.50 cm, a height of 6.11 cm and a pore volume of 1.42 cm 3 was tested.

[0068] Specifically, the core was saturated with water and saturated injection was carried out on the single-core of the core at a speed of 0.5 mL / min to detect the permeability k0 in the single-core of the core; then the suspension was injected into the single-core of the core to measure the permeability K1 of the core, and the plugging rate was calculated according to the permeability in the single-core of the core. The results are shown in Table 1.

[0069] Among them, the calculation formula of the temporary plugging rate is: temporary plugging rate = [(K0 - K1) / K0] × 100%.

[0070] 2. Abrasion resistance

[0071] The abrasion resistance of the flexible particles prepared in Example 1 and Comparative Examples 1-4 was tested using quartz sand with a particle size of 100 mesh as the abrasive. During the test, the abrasive flow rate was controlled at 10 g / min, the loading pressure was 1.0 MPa, the rotation speed was 50 r / min, and the wear time was 1 h. By recording the weight change of the flexible particles before and after wear, the wear rate was calculated. The results are shown in Table 1.

[0072] Among them, the wear rate (%) = [(weight before wear - weight after wear) / weight before wear] × 100%.

[0073] 3. Flexibility

[0074] The flexible particles prepared in Example 1 and Comparative Examples 1-4 were subjected to a tensile test, and the flexibility of the flexible particles was reflected by the length at the break of the flexible particles. The specific steps are as follows:

[0075] Select 10 flexible materials in each group as samples for testing. Place the flexible material at the hook of a spring tensile and compressive testing machine, and stretch the flexible particles outward from the hook point. When the flexible particles are broken, record the length of the flexible particles and take the average value. The results are shown in Table 1.

[0076] Table 1 Performance parameters of flexible particles in each group

[0077]

[0078] As can be seen from Table 1, the flexible particles prepared by the present invention using TPEE, plasticizer, filler, and dispersant as raw materials have good elasticity, plugging performance, and wear resistance. Specifically, the plugging rate of the flexible particles prepared by the present invention is 96.8%, the wear rate is 5.8%, and the elongation at break is 547.2%.

[0079] Among them, although TPEE has good resilience, its flexibility is poor. When it is used for profile control and water plugging, it cannot adapt to the deformation and creep of the formation. During the injection process into the formation, it may not easily pass through narrow pore channels and is likely to accumulate in the near-wellbore area, causing formation plugging and affecting the normal production of oil and water wells. At the same time, due to insufficient flexibility, it is difficult to form a uniform and stable plugging layer in pores and fractures after entering the formation. They may not be able to well fill irregular pore spaces, resulting in incomplete plugging and still existing water channeling paths, thereby reducing the effect of profile control and water plugging and being unable to effectively control oil well water production and improve oil recovery. The length at break of the flexible particles prepared without using a plasticizer in Comparative Example 2 is 18.51 mm, the length at break of the flexible particles prepared using only naphthenic oil as a plasticizer in Comparative Example 3 is 24.45 mm, the length at break of the flexible particles prepared using only bisphenol fluorene epoxy resin as a plasticizer in Comparative Example 3 is 20.60 mm, while the length at break of the flexible particles prepared by the present invention using naphthenic oil and bisphenol fluorene epoxy resin as plasticizers is 29.17 mm. It can be seen that naphthenic oil and bisphenol fluorene epoxy resin have a synergistic effect in improving the flexibility of flexible particles.

[0080] The above are only the preferred embodiments of the present application and are not used to limit the present application. For those skilled in the art, the present application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A flexible particle for oil recovery, characterized in that: The invention comprises the following raw materials in parts by weight: 40-70 parts of TPEE, 10-20 parts of plasticizer, 5-15 parts of filler, 2-6 parts of dispersant; The plasticizer is prepared by mixing cycloalkane oil and bisphenol fluorene epoxy resin in a mass ratio of (10-15):

1.

2. The flexible particles for oil recovery according to claim 1, characterized in that: The filler is calcium carbonate and / or talcum powder, and the dispersant is Tween-80.

3. The method for preparing the flexible particles for oil recovery according to claim 1 or 2, characterized in that: The following steps are involved: (1) After preheating TPEE, plasticizer and filler are added in sequence, and mixed to obtain a mixed rubber; The mixed rubber is extruded and granulated to obtain preformed particles; (2) Add the preformed particles to the dispersant solution, stir to emulsify and disperse, filter, wash and dry after cooling, and obtain the flexible particles for oil recovery.

4. The method for preparing flexible particles for oil recovery according to claim 3, characterized in that: In step (1), the preheating temperature is 120-150° C. and the preheating time is 5-10 min.

5. The method for preparing flexible particles for oil recovery according to claim 3, characterized in that: In step (1), the mixing temperature is 130-160° C. and the mixing time is 10-20 min.

6. The method for preparing flexible particles for oil recovery according to claim 3, characterized in that: In step (1), the extrusion granulation temperature is 120-150°C.

7. The method for preparing flexible particles for oil recovery according to claim 3, characterized in that: In step (1), the particle size of the preformed particles is 1-10 mm.

8. The method for preparing flexible particles for oil recovery according to claim 3, characterized in that: In step (2), the dispersant solution is a mixture of dispersant and water, and its mass concentration is 2%-5%.

9. The method for preparing flexible particles for oil recovery according to claim 3, characterized in that: In step (2), the stirring speed is 800-1500 rpm and the stirring time is 10-20 min.

10. Use of the flexible particles for oil recovery according to claim 1 or 2 in oil field development.

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