Sustained release proppant and methods of making the same

Abstract

The application provides a slow-release proppant and a preparation method thereof, and belongs to the technical field of proppants. The slow-release proppant comprises: solidifiable proppant particles; anti-fouling particles, which are doped with the solidifiable proppant particles, and the anti-fouling particles comprise an anti-fouling protective layer and a skeleton structure and an anti-fouling agent which are mutually penetrated in the anti-fouling protective layer; and / or, anti-wax particles, which are doped with the solidifiable proppant particles, and the anti-wax particles comprise an anti-wax protective layer and a skeleton structure and an anti-wax agent which are mutually penetrated in the anti-wax protective layer. In the application, the anti-fouling agent and / or the anti-wax agent are penetrated in the skeleton structure to form a core, and the core is coated with a protective layer, so that the slow-release time of the anti-fouling agent or the anti-wax agent is effectively prolonged. After the proppant reaches a predetermined position, the anti-fouling agent or the anti-wax agent is dissolved under the scouring condition of formation fluid, plays a role in preventing fouling and waxing, reduces the risk of pore throat blockage between proppant particles in an artificial fracture, and avoids pipeline blockage.

Description

Technical Field

[0001] This invention belongs to the field of proppant technology, specifically relating to a sustained-release proppant and its preparation method. Background Technology

[0002] Most of my country's onshore oilfields have entered the middle and late stages of development. The water content of the produced fluid increases, and the produced fluid contains a large number of anions and cations. When the ion concentration is supersaturated, scale will form, which will eventually cause scale to block the pores inside the reservoir, reduce oil and gas production, cause problems such as scale buildup in well pipelines, oil pump jamming, annulus blockage between well tubing and sucker rod, and scale buildup in oil gathering and transportation pipelines, which seriously affect oilfield development and production.

[0003] Currently, scale inhibition methods in oilfields often employ chemical methods, where scale inhibitors are added separately into the well. However, it is difficult for the scale inhibitors in this method to reach the target location. Even if some scale inhibitors do reach the target location, they are quickly carried away by the produced fluid, thus losing their scale inhibition effect.

[0004] Secondly, the presence of wax in some crude oils and changes in temperature and pressure can cause wax deposition. Once wax deposition occurs, the pores of the proppant are easily blocked. Wax deposition in oil wells affects the flow cross-section of fluid lift, increases flow resistance, and further affects the normal operation of pumping equipment, leading to frequent well shutdowns.

[0005] Therefore, suitable scale inhibitors or wax inhibitors are crucial for oilfield development. However, current scale inhibitors are coated on the surface of proppant to form a slow-release layer. During the proppant's entry into the formation, the violent collision between the proppant and the fracturing pipe causes severe damage to the proppant coating layer. The slow-release effect is short, the scale inhibitor is prone to failure, and it cannot meet the purpose of long-term slow release. The consolidation strength is reduced, and the preparation process is complicated. Summary of the Invention

[0006] The present invention aims to solve at least one of the technical problems existing in the prior art by providing a sustained-release proppant and its preparation method.

[0007] In one aspect, the present invention provides a sustained-release proppant, comprising:

[0008] Consolidable proppant particles;

[0009] Anti-scaling particles, inter-doped with the solidifiable proppant particles, wherein the anti-scaling particles include an anti-scaling protective layer and an interpenetrating skeleton structure and anti-scaling agent located within the anti-scaling protective layer; and / or,

[0010] The anti-wax particles are mixed with the solidifiable support particles, and the anti-wax particles include an anti-wax protective layer and a skeleton structure and anti-wax agent that penetrate each other within the anti-wax protective layer.

[0011] Optionally, when the slow-release proppant comprises anti-fouling particles, the anti-fouling agent comprises one or more of sodium polyepoxysuccinate, sodium amino-tris-methylene phosphonate, potassium hydroxy-ethylidene diphosphonate.

[0012] Optionally, the anti-fouling protective layer comprises a water-soluble binder and cement.

[0013] Optionally, when the slow-release proppant comprises anti-wax particles, the anti-wax agent is formed by mixing methanol, nonylphenol polyoxyethylene ether, dodecyl trimethyl ammonium chloride, and sodium perfluoro nonene oxy benzene sulfonate.

[0014] Optionally, the anti-wax protective layer comprises an oil-soluble binder and cement.

[0015] Optionally, the skeleton structure is formed by a reaction of nickel-iron slag powder, fly ash, and cement.

[0016] Optionally, the content ratio of the settable proppant particles to the anti-fouling particles and / or anti-wax particles is (70-95):(5-30).

[0017] In another aspect of the present application, a method for preparing the slow-release proppant described above is provided, the method comprising:

[0018] forming settable proppant particles;

[0019] forming anti-fouling particles and / or anti-wax particles;

[0020] mixing the settable proppant particles with the anti-fouling particles and / or anti-wax particles uniformly to obtain the slow-release proppant.

[0021] Optionally, the anti-fouling particles are formed by the following method, comprising:

[0022] adding fly ash, cement, nickel-iron slag powder, and an anti-fouling agent into a mixer in a certain ratio, transferring the mixture to a granulator after mixing, and spraying the mixture with a water-soluble binder to obtain anti-fouling particle semi-finished products;

[0023] sealing and curing the anti-fouling particle semi-finished products, adding a water-soluble binder solution and cement to the surface of the particles, and drying the particles to obtain anti-fouling particles.

[0024] Optionally, the anti-wax particles are formed by the following method, comprising:

[0025] adding fly ash, cement, nickel-iron slag powder, and an anti-wax agent into a mixer in a certain ratio, transferring the mixture to a granulator after mixing, and spraying the mixture with an oil-soluble binder and water to obtain anti-wax particle semi-finished products;

[0026] The anti-waxing granule semi-product is sealed and maintained, and is transferred into a sand mixer, and then an oil-soluble binder solution and cement are added until the surface of the granule is dry, to obtain the anti-waxing granule.

[0027] The present application provides a slow-release proppant and a preparation method thereof, wherein the slow-release proppant comprises: solidifiable proppant particles; anti-fouling particles intermixed with the solidifiable proppant particles, and the anti-fouling particles comprise an anti-fouling protective layer and a skeleton structure and an anti-fouling agent interpenetrating in the anti-fouling protective layer; and / or anti-waxing particles intermixed with the solidifiable proppant particles, and the anti-waxing particles comprise an anti-waxing protective layer and a skeleton structure and an anti-waxing agent interpenetrating in the anti-waxing protective layer. The anti-fouling agent and / or the anti-waxing agent are interpenetrated in the skeleton structure to form the core of the anti-fouling particles and / or the anti-waxing particles, and the anti-fouling agent or the anti-waxing agent is effectively extended in slow-release time by coating a protective layer outside the core, so that the anti-fouling agent or the anti-waxing agent is not easily invalid, and the anti-fouling agent or the anti-waxing agent is dissolved under the scouring condition of the formation fluid after the proppant reaches the predetermined position, to prevent fouling and waxing, reduce the risk of pore throat blockage between the proppant particles in the artificial fracture, avoid pipeline blockage, ensure the normal work of the oil extraction equipment, reduce the frequency of well shut-in, and improve the mining efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The flowchart of the preparation method of the slow-release proppant of an embodiment of the present application is shown. DETAILED DESCRIPTION

[0029] In order for those skilled in the art to better understand the technical solutions of the present application, the present application is further described in detail below in combination with the drawings and specific embodiments. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the described embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the protection scope of the present application.

[0030] In one aspect of the present application, a slow-release proppant is provided, comprising: solidifiable proppant particles, anti-fouling particles and / or anti-waxing particles, wherein the anti-fouling particles are intermixed with the solidifiable proppant particles, and the anti-fouling particles comprise an anti-fouling protective layer and a skeleton structure and an anti-fouling agent interpenetrating in the anti-fouling protective layer; the anti-waxing particles are also intermixed with the solidifiable proppant particles, and the anti-waxing particles comprise an anti-waxing protective layer and a skeleton structure and an anti-waxing agent interpenetrating in the anti-waxing protective layer. That is, the slow-release proppant can comprise the solidifiable proppant particles and the anti-fouling particles intermixed with each other, can comprise the solidifiable proppant particles and the anti-waxing particles intermixed with each other, and can comprise the solidifiable proppant particles, the anti-fouling particles and the anti-waxing particles intermixed with each other.

[0031] In the present embodiment, in the slow-release proppant, the anti-scaling particles and / or the anti-wax particles are intermixed with the settable proppant particles as functional particles, and are bonded into blocks in the formation to form integral support after entering the formation, so as to avoid the slow-release particles from being broken by the formation closure pressure, effectively prolong the slow-release period, and ensure the flow conductivity of the fracture; secondly, in the anti-scaling particles or the anti-wax particles, the anti-scaling agent or the anti-wax agent is interpenetrated with the skeleton structure to form the core of the functional particles, and is located in the corresponding anti-scaling protection layer or the anti-wax protection layer, so that the density of the functional particles is approximately equal to the density of the settable proppant particles, the settable proppant particles and the functional particles are prevented from being stratified during the injection of the slow-release proppant into the formation, the effect of slow release of the anti-scaling agent or the anti-wax agent is achieved, the slow-release effective period is further prolonged, and the long-term slow-release purpose is met.

[0032] In some preferred embodiments, the content ratio of the settable proppant particles to the anti-scaling particles and / or the anti-wax particles is (70-95):(5-30).

[0033] It should be noted that, in the present embodiment, the settable proppant particles are formed by the aggregate, the silane coupling agent, the thermoplastic phenolic resin, the paraformaldehyde powder or the urotropine, the settable proppant particles play a supporting role on the fracture, prevent the anti-scaling agent or the anti-wax agent particles from being broken by the formation closure pressure, and cause the anti-scaling agent or the anti-wax agent to be quickly dissolved out. The settable proppant particles are bonded into blocks under the formation conditions after entering the fracture, form integral support, even if the particle strength is reduced with the release of the effective substances in the anti-scaling particles or the anti-wax particles, the functional particle parts in the proppant are not collapsed, the effective components of the functional particles are effectively ensured to be released for a long time, and the flow conductivity of the fracture is also ensured.

[0034] It should be further noted that the skeleton structure in the anti-wax particles or the anti-scaling particles is formed by the nickel-iron slag powder, the fly ash and the cement reaction. That is, the anti-wax agent and / or the anti-scaling agent is mixed with the fly ash, the cement and the nickel-iron slag powder according to a certain ratio, and is subjected to processes such as mixing, granulation and curing, so that the anti-wax agent and / or the anti-scaling agent is interpenetrated in the skeleton structure. Based on the skeleton structure, the basic strength of the slow-release proppant can be ensured, the anti-scaling agent or the anti-wax agent is prevented from being quickly dissolved out due to the breakage of the functional particles, the release speed is reduced, and the slow-release effective period is prolonged.

[0035] In some preferred embodiments, when the slow-release proppant includes the anti-scaling particles, the anti-scaling agent is intermixed with the skeleton structure to form the core of the anti-scaling particles, the anti-scaling protection layer is coated on the outer layer of the core, and the anti-scaling protection layer includes the water-soluble binder and the cement. Based on the anti-scaling protection layer, the initial strength of the anti-scaling particles is formed, the anti-scaling protection layer plays a supporting and protecting role on the core anti-scaling agent, so as to prevent the anti-scaling agent from being dissolved out when the proppant does not reach the predetermined position. In this way, after the proppant reaches the predetermined position, the anti-scaling agent is dissolved out under the scouring condition of the formation fluid, so as to prevent the scaling of the cations and anions in the produced liquid and the plugging of the pores.

[0036] As a further preferred aspect, the scale inhibitor includes one or more of sodium polyepoxysuccinate, sodium amino-tris-methylene phosphonate, and potassium hydroxy-ethylidene diphosphonate.

[0037] As a further preferred aspect, the water-soluble binder can be polyethylene glycol or the like.

[0038] As a further preferred aspect, the ratio of the nickel-iron slag powder, fly ash, cement, and scale inhibitor ranges from 50-150:100-300:300-500:50-150.

[0039] In the present embodiment, after the slow-release proppant with scale-preventing effect is pumped into the formation, the proppant particles can be consolidated under formation conditions to ensure effective support of the fracture. During oilfield production, when water contacts the scale-preventing particles, the water-soluble binder in the outer protective layer dissolves, exposing the inner core. The scale inhibitor dissolves upon contact with water and is produced along with the fluid, achieving the scale-preventing effect. In addition, the scale inhibitor is distributed throughout the entire skeleton structure particle, thus ensuring the effective period of the scale inhibitor. After the scale inhibitor dissolves, the skeleton structure formed based on other powder materials ensures that the powder does not fall off. In addition, the consolidation of the proppant particles ensures that the particles do not break, thus achieving the scale-preventing effect while ensuring the flow conductivity of the fracture.

[0040] In other preferred embodiments, when the slow-release proppant includes a scale-preventing particle, the scale-preventing agent and the skeleton structure are doped with each other to form the inner core of the scale-preventing particle. The scale-preventing protective layer is coated on the outer layer of the inner core, and the scale-preventing protective layer includes an oil-soluble binder and cement. The initial strength of the scale-preventing particle is based on the scale-preventing protective layer, which supports and protects the inner core of the scale-preventing agent to prevent the scale-preventing agent from dissolving before the proppant reaches the preset position. Thus, under the scouring conditions of the formation fluid, the scale-preventing agent dissolves when the proppant reaches the preset position, preventing the wax in the crude oil and the wax precipitation of the crude oil from blocking the pores and further reducing the flow resistance of the fluid.

[0041] As a further preferred aspect, the scale-preventing agent is formed by mixing methanol, nonylphenol polyoxyethylene ether, dodecyltrimethylammonium chloride, and sodium perfluoro-nonylene oxybenzenesulfonate.

[0042] As a further preferred aspect, the oil-soluble binder can be phenol-formaldehyde resin or the like.

[0043] As a further preferred aspect, the ratio of the nickel-iron slag powder, fly ash, cement, and scale inhibitor ranges from 1.5-2.5:1.5-2.5:5-7:0.5-0.9.

[0044] In the present embodiment, the slow-release proppant with the wax-proofing effect is introduced into the formation, and the proppant particles can be bonded under the formation conditions to ensure effective support of the fracture. During the oilfield production, when the oil contacts the wax-proofing particles, the oil-soluble bonding agent in the outer protective layer dissolves to expose the inner core, the wax-proofing agent contacts the oil, dissolves, and is then produced with the fluid, thereby achieving the effect of preventing wax deposition. In addition, the wax-proofing agent penetrates through the entire skeleton structure of the particle, thereby ensuring the effective period of the wax-proofing agent, and the skeleton formed by the other powder materials ensures that the powder does not fall off after the wax-proofing agent dissolves. In addition, the support of the settable proppant also ensures that the particle does not break, thereby achieving the effect of preventing wax deposition while ensuring the conductivity of the fracture.

[0045] In the present embodiment, the wax-proofing agent and / or the wax-proofing agent included in the proppant is not easily dissolved, thereby prolonging the effective period of preventing wax deposition, and the density of the wax-proofing particles and / or the wax-proofing particles is close to that of the settable proppant particles, thereby avoiding stratification during injection.

[0046] As shown in Figure 1 Another aspect of the present application provides a preparation method S100 of the slow-release proppant, which includes steps S110-S130.

[0047] S110, forming settable proppant particles.

[0048] Specifically, 2 kg of aggregate is heated to 220-180°C, and then poured into a sand mixer. When the temperature is reduced to 150-180°C, 1-5 g of a silane coupling agent is added, stirred for 10-15 s, and then 10-15 g of a thermoplastic phenolic resin with a softening point of 80-100°C is added. After stirring for 20-30 s, 10% of the amount of resin of polyformaldehyde powder is added, and stirring is continued until complete dispersion. The settable proppant particles are obtained after sieving.

[0049] S120, forming wax-proofing particles and / or wax-proofing particles.

[0050] In some preferred embodiments, the wax-proofing particles are formed by the following method: fly ash, cement, nickel-iron slag powder, and a wax-proofing agent are added to a mixing machine in a ratio of 50-150:100-300:300-500:50-150, uniformly mixed, and then transferred to a granulator. A polyethylene glycol solution is sprayed to prepare wax-proofing particle semi-finished products. Then, the products are sealed and cured for 24 h. After curing, the products are transferred to a sand mixer, polyethylene glycol solution is added, and then cement is added until the surface of the particles is dry, thereby obtaining the wax-proofing particles.

[0051] It should be noted that the fly ash can be fly ash with a particle size of not greater than 45 μm to ensure the fineness of the powder for granulation, thereby ensuring the yield and the smooth surface of the prepared particles, which meets the general requirements for proppant granulation.

[0052] The scale inhibitor comprises one or more of sodium polyepoxysuccinate, sodium amino-tris-methylene phosphonic acid, and potassium hydroxyethylidene diphosphonate.

[0053] In some preferred embodiments, the anti-wax particles are formed by the following method: fly ash, cement, nickel-iron slag powder, and anti-wax agent are added into a mixer in a ratio of 1.5-2.5:1.5-2.5:5-7:0.5-0.9, and after mixing, the mixture is transferred into a granulator, and an anti-wax agent solution with a weight ratio of 1:1 is sprayed to prepare anti-wax particle semi-products, which are then sealed and cured for 24 hours, and then transferred into a sand mixer, phenolic resin solution is added, and then cement is added until the surface is dry, to obtain the anti-wax particles.

[0054] The anti-wax agent is formed by the following process: methanol, nonylphenol polyoxyethylene ether, dodecyltrimethylammonium chloride, and sodium perfluoro-n-alkenylene oxybenzenesulfonate are mixed in a mass ratio of 40-50:10-20:5-10:0.1-0.5, and then filtered to obtain the anti-wax agent.

[0055] In this embodiment, the nickel-iron slag powder, fly ash, and cement can react to form a skeleton structure with certain strength, and the added scale inhibitor and / or anti-wax agent penetrates the entire skeleton structure, increasing the effective period of scale inhibition; at the same time, the density of the formed anti-wax particles and / or scale inhibitor particles is close to that of the settable proppant particles, avoiding stratification during injection, and ultimately ensuring the scale inhibition and anti-wax effects.

[0056] S130, mixing the settable proppant particles with the scale inhibitor particles and / or anti-wax particles uniformly to obtain the slow-release proppant.

[0057] In some preferred embodiments, the scale inhibitor particles and the settable proppant particles are mixed uniformly in a ratio of 5-15:75-95 to obtain the slow-release proppant with scale inhibition function.

[0058] For example, 10 g of scale inhibitor particles and 80 g of settable proppant particles are mixed uniformly to obtain the slow-release proppant with scale inhibition function.

[0059] In some preferred embodiments, the anti-wax particles and the settable proppant particles are mixed uniformly in a ratio of 5-15:75-95 to obtain the slow-release proppant with anti-wax function.

[0060] For example, 10 g of anti-wax particles and 80 g of settable proppant particles are mixed uniformly to obtain the slow-release proppant with anti-wax function.

[0061] In some other preferred embodiments, the anti-wax particles, the anti-scaling particles and the solidifiable proppant particles are mixed uniformly at a ratio of 5-15:5-15:70-90 to obtain the slow-release proppant with anti-wax and anti-scaling functions.

[0062] By way of example, 10 g of the anti-scaling particles, 10 g of the anti-wax particles and 80 g of the solidifiable proppant particles are mixed uniformly to obtain the multifunctional slow-release proppant with anti-scaling and anti-wax functions.

[0063] The preparation method of the present application is simple. By mixing the anti-scaling particles and / or the anti-wax particles with the solidifiable proppant particles, the slow-release proppant is formed. The slow-release proppant is bonded into a block under the formation conditions after entering the fractures, forming an integral support to play a supporting role on the fractures. Even if the anti-scaling agent in the anti-scaling particles or the anti-wax agent in the anti-wax particles is dissolved out, the strength of the proppant is reduced, but the effective support on the fractures can still be ensured, thereby ensuring the fracture conductivity. In addition, the slow-release proppant of the present application can also prolong the effective period of release of the anti-scaling agent or the anti-wax agent, thereby enhancing the anti-scaling or anti-wax effect.

[0064] The preparation method of the slow-release proppant will be further described below in combination with several specific embodiments:

[0065] Embodiment 1

[0066] The preparation method of the slow-release proppant in this example includes the following steps:

[0067] S1, preparing the anti-scaling particles:

[0068] 100 g of fly ash with a particle size of not more than 45 μm, 200 g of cement, 500 g of nickel slag powder, 70 g of sodium polyepoxysuccinate and 30 g of sodium hydroxyethylidene diphosphonate are added into a strong mixer, mixed uniformly and then transferred into a granulator. The granulator is started and 5% polyethylene glycol solution is sprayed into the granulator by using a atomizing device during the rotation. After the disc granulator rotates for 10 minutes, the anti-scaling particle semi-finished product is obtained by sealing and curing for 24 hours. After the curing is completed, the anti-scaling particle semi-finished product is transferred into a sand mixer, polyethylene glycol solution is added, then cement is added until the surface of the particles is dry, and then the anti-scaling particles are obtained by sieving to the specified size by using a screen.

[0069] S2, preparing the solidifiable proppant particles:

[0070] 2 kg of 425-850 μm aggregate is heated to 200℃, then poured into a sand mixer, 1 g of silane coupling agent is added when the temperature is reduced to 160℃, stirred for 10 s, then 15 g of thermoplastic phenolic resin with a softening point of 80-100℃ is added, stirred for 30 s, then 1.5 g of paraformaldehyde powder is added, and the solidifiable proppant particles are obtained by stirring until completely dispersed and then sieving.

[0071] S3, preparing the slow-release proppant:

[0072] 10g of the anti-fouling particles and 90g of the settable proppant particles (both particle size specifications are the same) are mixed uniformly in a mixing device to obtain the slow-release proppant.

[0073] Further, 20mL of the proppant is measured and placed into an artificial core mold, preheated and pressurized, and kept at a constant temperature of 80℃ and a constant pressure of 30MPa for 24h, after demolding, the artificial core is placed into a core holder, and the annular pressure is introduced, and distilled water is injected into the core at a constant flow rate from one end of the holder using a laminar pump, and after collecting the liquid, the anti-fouling performance is detected according to SY / T5673-2020, and the results are shown in Tables 1, 2 and 3.

[0074] As shown in Tables 1 to 3, the anti-fouling rate of the slow-release proppant prepared in Example 1 on calcium carbonate is 98%, the anti-fouling rate on calcium sulfate is 97%, the anti-fouling effective period is 27 months, the breakage rate is 6.89% under the condition of 42MPa, the turbidity of the proppant is 13.5NTU, and the core permeability is 5.2μm 2 ·cm.

[0075] Example 2

[0076] The preparation method of the slow-release proppant in this example includes the following steps:

[0077] S1, preparation of anti-fouling particles:

[0078] 100g of fly ash with a particle size not greater than 45μm, 200g of cement, 500g of nickel-iron slag powder, and 100g of polyepoxysuccinic acid sodium are added to a powerful mixer, mixed uniformly, and then transferred to a granulator, the granulator is started, and 5% polyethylene glycol solution is sprayed into the granulator during rotation using a atomizing device, after the disc granulator rotates for 10 minutes, the anti-fouling particle semi-finished product is taken out, sealed and cured for 24h, then transferred to a sand mixer, polyethylene glycol solution is added, then cement is added until the surface of the particles is dry, and then sieved to the predetermined specification using a screen to obtain the anti-fouling particles.

[0079] S2, preparation of settable proppant particles:

[0080] 2kg of 425-850μm quartz sand aggregate is heated to 200℃, then poured into a sand mixer, 1g of silane coupling agent is added when the temperature is reduced to 160℃, stirred for 10s, then 15g of thermoplastic phenolic resin with a softening point of 80-100℃ is added, stirred for 30s, then 1.5g of polyformaldehyde powder is added, and stirred until completely dispersed, and then sieved to obtain the settable proppant particles.

[0081] S3, preparation of slow-release proppant:

[0082] The 13g anti-fouling particles, 87g of the settable proppant particles (both particle size specifications are the same) are mixed in the mixing device to obtain the slow-release proppant.

[0083] Further, the anti-fouling performance detection of the slow-release proppant of this embodiment 2 is the same as that of embodiment 1.

[0084] As shown in Tables 1-3, the anti-fouling rate of the slow-release proppant prepared in this embodiment 2 is 97% for calcium carbonate, 96% for calcium sulfate, the anti-fouling effective period is 32 months, the breakage rate is 7.12% under the condition of 42MPa, the turbidity of the proppant is 12.8NTU, and the core permeability is 4.8μm 2 ·cm.

[0085] Table 1 Anti-fouling performance results of the slow-release proppant formed in embodiments 1-2

[0086]

[0087] Table 2 General performance of the slow-release proppant formed in embodiments 1-2

[0088]

[0089] Table 3 Core permeability of the slow-release proppant formed in embodiments 1-2

[0090]

[0091]

[0092] Embodiment 3

[0093] The preparation method of the slow-release proppant in this example includes the following steps:

[0094] S1, preparing anti-wax particles:

[0095] The fly ash, cement, nickel-iron slag powder and anti-wax agent with particle size not greater than 45μm are added into the mixing machine in a ratio of 1.5:2:6:0.5, mixed uniformly, transferred to the granulator, prepared into anti-wax particle semi-finished product by the method of spraying granulation with anti-wax agent and water in a weight ratio of 1:1, then sealed and cured for 24h, transferred to the sand mixer after the curing is completed, added with phenolic resin solution, then added with cement until the surface is dry, and the anti-wax particles are obtained.

[0096] The methanol, nonylphenol polyoxyethylene ether, dodecyltrimethylammonium chloride and sodium perfluoro-nonyleneoxybenzenesulfonate are mixed uniformly in a mass ratio of 40:15:10:0.3, filtered, and the liquid is the anti-wax agent.

[0097] S2, preparing settable proppant particles:

[0098] 2kg of 425-850μm aggregate was heated to 200℃, then poured into a sand mixer, 1g of silane coupling agent was added when the temperature was reduced to 160℃, stirred for 10s, then 15g of thermoplastic phenolic resin with a softening point of 80-100℃ was added, 1.5g of polyformaldehyde powder was added after stirring for 30s, and the mixture was stirred until completely dispersed, and then sieved to obtain the settable proppant particles.

[0099] S3, preparation of slow-release proppant

[0100] 10g of wax-proofing particles and 90g of settable proppant particles (both with the same particle size specification) were mixed in a mixing device to obtain the slow-release proppant.

[0101] Further, 20mL of the proppant was measured and placed into an artificial core mold, preheated, pressurized, and kept at a constant temperature of 80℃ and a constant pressure of 30MPa for 24h, after demolding, the artificial core was placed into a core holder, and the annular pressure was introduced, and distilled water was injected into the core at a constant flow rate from one end of the holder using a laminar flow pump, and the liquid was collected and subjected to wax-proofing performance detection according to SY / T 6300-2009, and the results are shown in Tables 4, 5, and 6.

[0102] As shown in Tables 4-6, the wax-proofing rate of the slow-release proppant prepared in Example 3 was 80%, the effective period was 28 months, the breakage rate was 6.78% under the condition of 42MPa, the turbidity of the proppant was 23.9NTU, and the core permeability was 4.8μm 2 ·cm.

[0103] Example 4

[0104] S1, preparation of wax-proofing particles:

[0105] Fly ash, cement, nickel-iron slag powder, and wax-proofing agent with a particle size of not more than 45μm were added to a mixing machine in a ratio of 2:2:6:0.6, mixed, transferred to a granulator, and the wax-proofing agent was sprayed and granulated using a solution with a weight ratio of 1:1 to prepare wax-proofing particle semi-finished products, then sealed and cured for 24h, transferred to a sand mixer after curing, added with a phenolic resin solution, and then added with cement until the surface was dry, to obtain the wax-proofing particles.

[0106] The mass ratio of methanol: nonylphenol polyoxyethylene ether: dodecyltrimethylammonium chloride: sodium perfluoro-nonyleneoxybenzenesulfonate was 45:15:8:0.4, and after mixing and filtering, the liquid was obtained as the wax-proofing agent.

[0107] S2, preparation of settable proppant particles:

[0108] 2kg of 425-850μm aggregate is heated to 200°C, then poured into a sand mixer, 1g of silane coupling agent is added when the temperature is reduced to 160°C, stirred for 10s, then 15g of thermoplastic phenolic resin with a softening point of 80-100°C is added, stirred for 30s, then 1.5g of polyformaldehyde powder is added, stirred until completely dispersed, and then sieved to obtain the settable proppant particles.

[0109] S3, preparing the slow-release proppant

[0110] 15g of wax-proofing particles and 85g of settable proppant particles (both with the same particle size) are mixed in a mixing device to obtain the slow-release proppant.

[0111] Further, the wax-proofing performance of the slow-release proppant of Example 4 is detected in the same way as in Example 3.

[0112] As shown in Tables 4-6, the wax-proofing rate of the slow-release proppant prepared in Example 4 is 83%, the effective period is 30 months, the breakage rate is 6.12% under the condition of 42MPa, the turbidity of the proppant is 32.5NTU, and the core permeability is 5.2μm2·cm. 2

[0113] Table 4 wax-proofing performance results of the slow-release proppant formed in Example 3-4

[0114]

[0115] Table 5 general performance of the slow-release proppant formed in Example 3-4

[0116]

[0117] Table 6 core permeability of the slow-release proppant formed in Example 3-4

[0118]

[0119] Example 5

[0120] The preparation method of the slow-release proppant in this example includes the following steps:

[0121] S1, preparing the wax-proofing particles, same as in Example 3.

[0122] S2, preparing the scale-proofing particles, same as in Example 1

[0123] S3, preparing the settable proppant particles, same as in Example 1:

[0124] S4, preparing the slow-release proppant:

[0125] ​10g of the anti-wax granules, 10g of the anti-fouling granules, and 80g of the solidifiable proppant granules (both granules have the same particle size specification) are added into a mixing device and mixed uniformly to obtain the core layer.

[0126] Further, the anti-fouling and anti-wax performance of the proppant is detected according to Embodiment 1 and Embodiment 3, respectively, and the results are shown in Tables 7, 8, and 9.

[0127] As shown in Tables 7 to 9, the anti-wax rate of the slow-release proppant prepared in this embodiment 5 is 82%, the anti-wax effective period is 25 months, the anti-fouling rate on calcium carbonate is 96%, the anti-fouling rate on calcium sulfate is 93%, the anti-fouling effective period is 26 months, the crushing rate under the condition of 42MPa is 7.93%, and the turbidity of the proppant is 33.4NTU.

[0128] Table 7 Anti-wax performance results of the slow-release proppant formed in Embodiment 5

[0129]

[0130] Table 8 Anti-fouling performance results of the slow-release proppant formed in Embodiment 5

[0131]

[0132] Table 9 Conventional performance of the slow-release proppant formed in Embodiment 5

[0133]

[0134] In summary, the slow-release proppant formed in each of the above embodiments has a high anti-fouling rate and anti-wax rate, can effectively prevent calcium ion from fouling, has a good anti-fouling and anti-wax effect, and has a long anti-fouling effective period and anti-wax effective period.

[0135] The present application provides a slow-release proppant and a preparation method thereof, which has the following beneficial effects:

[0136] Firstly, the anti-fouling agent and / or the anti-wax agent are added as raw materials into the skeleton structure to form anti-fouling granules and / or anti-wax granules, and then the anti-fouling granules and / or the anti-wax granules are mixed with the solidifiable proppant granules, which simultaneously plays the roles of supporting and anti-fouling, anti-wax, etc., easily carries the anti-fouling agent and the anti-wax agent to the target position, prolongs the slow-release effective period, and prevents the anti-fouling agent and the anti-wax agent from being ineffective, which can effectively prevent the cation and anion in the produced liquid from fouling, the crude oil from waxing, and the fluid flow resistance from being reduced;

[0137] Secondly, the solidifiable proppant granules are bonded to form effective support, which prevents the anti-fouling granules and / or the anti-wax granules from being crushed, not only guarantees the effective period, but also guarantees the flow conductivity;

[0138] Third, the coating material of the slow-release proppant is water-soluble, and the scale inhibitor can be released only when water is contacted, further increasing the effective period;

[0139] Fourth, the preparation process of the present application is simple, only the solidifiable proppant particles are mixed with the scale-preventing particles and / or the wax-preventing particles, and the slow-release proppant can be obtained, meeting the purpose of long-time slow release, without complex preparation process, and reducing the preparation cost.

[0140] It can be understood that the above embodiments are only exemplary embodiments for illustrating the principles of the present application, and the present application is not limited thereto. Various modifications and improvements can be made by those skilled in the art without departing from the spirit and essence of the present application, and these modifications and improvements are also considered as the protection scope of the present application.

Claims

1. A slow-release proppant characterized in that, include: Consolidable proppant particles are formed from aggregates, silane coupling agents, thermoplastic phenolic resins, paraformaldehyde powder, or hexamethylenetetramine. Anti-scaling particles, inter-doped with the solidifiable proppant particles, wherein the anti-scaling particles include an anti-scaling protective layer and an interpenetrating skeleton structure and anti-scaling agent located within the anti-scaling protective layer, the anti-scaling protective layer comprising a water-soluble binder and cement; and / or, The anti-wax particles are mixed with the solidifiable support particles, and the anti-wax particles include an anti-wax protective layer and an interpenetrating skeleton structure and anti-wax agent located within the anti-wax protective layer. The anti-wax protective layer includes an oil-soluble binder and cement. The skeleton structure is formed by the reaction of nickel-iron slag powder, fly ash and cement. When the slow-release proppant includes anti-scaling particles, the anti-scaling agent includes one or more of sodium polyoxysuccinate, sodium aminotrimethylphosphonate, and potassium hydroxyethylidene diphosphonate. When the sustained-release proppant includes anti-wax particles, the anti-wax agent is formed by mixing methanol, nonylphenol polyoxyethylene ether, dodecyltrimethylammonium chloride, and sodium perfluorononenoxybenzenesulfonate. The content ratio of the solidifiable proppant particles to the anti-scaling particles and / or anti-wax particles is (70-95):(5-30).

2. A method of making the slow release proppant of claim 1, characterized in that, The method includes: Formation of solidifiable proppant particles; Forms anti-scaling particles and / or anti-waxing particles; The solidifiable proppant particles are mixed evenly with anti-scaling particles and / or anti-wax particles to obtain a slow-release proppant.

3. The method of claim 2, wherein, The anti-scaling particles are formed using the following method: Fly ash, cement, nickel-iron slag powder, and scale inhibitor are added to a mixer according to a certain ratio, mixed evenly, and then transferred to a granulator. Water-soluble binder is used for spray granulation to obtain scale inhibitor granules. The anti-scaling granules are sealed and cured, then transferred to a sand mixer, where a water-soluble binder solution is added, and cement is added until the granule surface is dry to obtain anti-scaling granules.

4. The method of claim 2, wherein, The anti-wax particles are formed by the following method, including: Fly ash, cement, nickel-iron slag powder, and anti-wax agent are added to a mixer according to a certain ratio, mixed evenly, and then transferred to a granulator. The mixture is sprayed with an oil-soluble binder and water solution to obtain anti-wax granules semi-finished product. The semi-finished anti-wax granules are sealed and cured, then transferred to a sand mixer, where an oil-soluble binder solution is added, and cement is added until the surface of the granules is dry to obtain anti-wax granules.

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