Method for green utilization of water-based rock debris through low-temperature sintering and low-temperature sintering equipment

Abstract

According to the low-temperature sintering method for green utilization of the water-based rock debris and the low-temperature sintering equipment, the adopted low-temperature sintering equipment has pressurization and temperature control functions, pressurization can be conducted under the closed condition, pressurization can also be conducted under the open condition, and external conditions can be provided for the sintering process; the method is specifically divided into two processes: in the first process, low-temperature sintering is carried out by applying certain pressure and temperature in a closed environment (closing a pressure release valve); in the second process, an instant sintering aid is used in an auxiliary mode in an open environment (a pressure release valve is opened), the sintering aid effect is provided for the sintering process by means of volatility and cohesiveness of the instant sintering aid, and the instant sintering aid completely or partially leaves the product in a short time to play a role in promoting densification. Under the combined action of the two processes, the material can be densified at the temperature of 200 DEG C, so that the fracturing material with the relative density larger than 0.90 and the breakage rate smaller than 10% can be obtained at the temperature of 200 DEG C or below, and the fracturing material can be used for hydraulic fracturing of oil and gas exploitation.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental protection and resource recycling, and in particular relates to a method for green utilization of water-based rock cuttings by low-temperature sintering and low-temperature sintering equipment. Background Art

[0002] Water-based rock cuttings are a type of solid waste generated during oil exploration and development, with the main components being shale, bentonite, lubricants, chlorides, etc. If water-based rock cuttings are not treated or treated improperly, they can easily cause environmental pollution and harm human health. In recent years, with the increasing attention paid to environmental issues, solid wastes are required to be reduced, environmentally friendly, and recycled.

[0003] Investigations have shown that my country does not yet have the ability to process water-based rock cuttings in an efficient, large-scale, and industrialized manner. At present, existing technologies usually use landfill, incineration, brick making and other methods to process water-based rock cuttings. The method of calcining bricks is to use high temperatures (greater than 1000°C) to calcine water-based rock cuttings to make bricks, which results in excessively high sintering temperatures and high production costs. More importantly, high-temperature calcining bricks has problems such as excessively high calcining temperatures, high energy consumption, and environmental unfriendliness, which do not meet the requirements of low carbon and environmental protection. The existing technology also has a method of sintering water-based rock cuttings to prepare ceramsite proppants, but this method still has the problem of excessively high sintering temperatures (greater than 900°C), and inevitably has problems such as high energy consumption and environmental unfriendliness.

[0004] Therefore, it is urgent to develop pollution-free, low-energy, low-carbon and environmentally friendly methods to achieve the green recycling of water-based cuttings. Summary of the invention

[0005] In view of the technical bottleneck existing in the current field of recycling of water-based rock cuttings, namely the problem of too high processing temperature, the present invention provides a method for green utilization of water-based rock cuttings by low-temperature sintering and a low-temperature sintering device.

[0006] The present invention is achieved through the following technical solutions:

[0007] A method for low-temperature sintering and green utilization of water-based rock cuttings, the method is implemented by low-temperature sintering equipment; the low-temperature sintering equipment comprises: a heat preservation device, an upper press, a pressure shaft, a sintering chamber, a sintering tank and a sintering tank pressure shaft;

[0008] The heat preservation device is used to provide heat to the sintering chamber and control the temperature in the sintering chamber; the sintering tank is arranged in the sintering chamber;

[0009] A sintering tank pressure shaft is arranged on the bottom surface of the pressure shaft, and the sintering tank pressure shaft is adapted to the sintering tank; a gas channel is opened inside the pressure shaft, the gas channel inlet is located on the bottom surface of the pressure shaft, and the gas channel outlet is a pressure relief port and is located on the upper side of the pressure shaft; the upper press is used to apply downward pressure on the top of the pressure shaft;

[0010] The method specifically comprises:

[0011] Mixing water-based rock cuttings and an instant sintering aid to obtain a mixture; the instant sintering aid is one or more of water, siloxane, silicic acid, silicic acid derivatives, ammonia water, urea and alkali;

[0012] The mixture is placed in a sintering tank, the pressure shaft is extended into the sintering chamber, the pressure relief port is closed, a closed environment is formed in the sintering chamber, a downward pressure of 100MPa to 500MPa is applied by the upper press, and the temperature of the sintering chamber is controlled at 100℃ to 200℃ by the heat preservation device to carry out a low-temperature sintering reaction;

[0013] After the low-temperature sintering reaction is completed, the upper press stops applying pressure and opens the pressure relief port. When the pressure in the sintering chamber drops to atmospheric pressure, the pressure shaft of the sintering tank contacts the mixture in the sintering tank. The upper press applies a downward pressure of 100MPa to 500MPa and performs a densification reaction at a temperature of 100℃ to 200℃ to obtain a fracturing material.

[0014] Preferably, the water-based rock cuttings are a mixture of type A water-based rock cuttings containing Al2O3 and type B water-based rock cuttings containing SiO2.

[0015] Further, the type A water-based rock cuttings are calculated as Al2O3, the type B water-based rock cuttings are calculated as SiO2, and the molar ratio of the type A water-based rock cuttings to the type B water-based rock cuttings is less than or equal to 0.5.

[0016] Preferably, the instantaneous sintering aid accounts for 1% to 4% of the mass of the water-based rock cuttings.

[0017] Preferably, the low-temperature sintering reaction time is 1 to 4 hours.

[0018] Preferably, a plurality of sintering tanks and sintering tank pressure axes are provided, and the sintering tank pressure axes correspond to the sintering tanks one by one.

[0019] Preferably, the low temperature sintering equipment further comprises: an upper pressing plate, a lower pressing plate, an upper pad, a lower pad and a lead screw;

[0020] The sintering chamber is arranged on the top of the lower pad, the lower pad is arranged on the top of the lower pressing plate, the upper pad is arranged on the top of the pressure shaft, the upper pressing plate is arranged on the top of the upper pad, and the upper pressing plate and the lower pressing plate are connected by a lead screw;

[0021] The upper pad is connected to the top of the upper pressing plate, the upper press applies downward pressure on the top of the upper pressing plate, and the lower press applies upward pressure on the bottom of the lower pressing plate.

[0022] A low-temperature sintering device, comprising: a heat preservation device, an upper press, a pressure shaft, a sintering chamber, a sintering tank and a sintering tank pressure shaft;

[0023] The heat preservation device is used to provide heat to the sintering chamber and control the temperature in the sintering chamber; the sintering tank is arranged in the sintering chamber;

[0024] A sintering tank pressure shaft is arranged on the bottom surface of the pressure shaft, and the sintering tank pressure shaft is adapted to the sintering tank; a gas channel is opened inside the pressure shaft, the gas channel inlet is located on the bottom surface of the pressure shaft, and the gas channel outlet is a pressure relief port and is located on the upper side of the pressure shaft; the upper press is used to apply downward pressure on the top of the pressure shaft.

[0025] Preferably, a plurality of sintering tanks and sintering tank pressure axes are provided, and the sintering tank pressure axes correspond to the sintering tanks one by one.

[0026] Preferably, it also includes: an upper pressing plate, a lower pressing plate, an upper pad, a lower pad and a lead screw;

[0027] The sintering chamber is arranged on the top of the lower pad, the lower pad is arranged on the top of the lower pressing plate, the upper pad is arranged on the top of the pressure shaft, the upper pressing plate is arranged on the top of the upper pad, and the upper pressing plate and the lower pressing plate are connected by a lead screw;

[0028] The upper pad is connected to the top of the upper pressing plate, the upper press applies downward pressure on the top of the upper pressing plate, and the lower press applies upward pressure on the bottom of the lower pressing plate.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The present invention provides a method for low-temperature sintering and green utilization of water-based rock cuttings. The low-temperature sintering equipment used has pressurization and temperature control functions, and can be pressurized under closed conditions or under open conditions, and can provide external conditions for the sintering process. It is specifically divided into two processes: the first process is to perform low-temperature sintering under a closed environment (close the pressure relief valve) by applying a certain pressure and temperature; the second process is to use an instantaneous sintering agent in an open environment (open the pressure relief valve), and use the volatility and adhesiveness of the instantaneous sintering agent to provide a sintering effect for the sintering process. It is important that the instantaneous sintering agent completely or partially leaves the product in a short time, which plays a role in promoting densification. The two processes work together to make the material densified at 200°C, so that a fracturing material with a relative density greater than 0.90 and a crushing rate less than 10% can be obtained below 200°C, which can be used for hydraulic fracturing in oil and gas production. The present invention does not require a high-temperature process, effectively reduces the processing temperature of water-based rock cuttings (below 200°C), and obtains a key engineering material for hydraulic fracturing-fracturing material. The entire synthesis process of the present invention is pollution-free, low-energy, low-carbon and environmentally friendly, thereby realizing low-temperature green recycling of solid waste - water-based rock cuttings, which is conducive to promotion in the field of environmental protection and resource recycling technology and has broad application prospects.

[0031] Furthermore, the present invention uses type A water-based rock cuttings and type B water-based rock cuttings as raw materials to prepare fracturing materials of mullite phase with high mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a schematic diagram of a low temperature sintering device used in Example 1 of the present invention;

[0033] Figure 2 Schematic diagram of a horizontal cross section of a sintering chamber and a sintering tank in a low-temperature sintering device used in Example 1 of the present invention;

[0034] Figure 3 It is a schematic diagram of a horizontal cross-section of a sintering chamber, a sintering tank, and a gas channel in a low-temperature sintering device used in Example 1 of the present invention;

[0035] Figure 4 is a schematic diagram of a longitudinal cross-section of a pressure axis in a low-temperature sintering device used in Example 1 of the present invention;

[0036] Figure 5 is a SEM image of the fracturing material obtained in Example 3 of the present invention;

[0037] Figure 6 This is the XRD diagram of the fracturing material obtained in Example 3 of the present invention, and mullite is a mullite phase.

[0038] Among them, 1-1-1 upper press, 1-2-lower press, 2-heat preservation device, 3-pressure shaft, 4-pressure relief port, 5-sintering chamber, 6-upper pressing plate, 7-lower pressing plate, 8-screw, 9-1-upper pad, 9-2-lower pad, 10-sintering tank, 11-gas channel, 12-sintering tank pressure shaft, 13-longitudinal projection of gas channel inlet. DETAILED DESCRIPTION

[0039] In order to further understand the present invention, the present invention is described below in conjunction with embodiments. These descriptions are only to further explain the features and advantages of the present invention and are not intended to limit the claims of the present invention.

[0040] The method for low-temperature sintering and green utilization of water-based rock cuttings of the present invention uses water-based rock cuttings as raw materials, adopts self-made low-temperature sintering equipment, and assists with instantaneous sintering aids. Through the sintering process, a mullite phase with high mechanical properties is generated, and ceramsite grains are densified. A fracturing material with a relative density greater than 0.90 and a crushing rate less than 10% is obtained below 200°C, and the fracturing material can be used for hydraulic fracturing in oil and gas production.

[0041] The self-made low-temperature sintering equipment of the present invention has pressurization and temperature control functions, and can provide external conditions for the sintering process, including pressure and temperature. The present invention uses an auxiliary instant sintering aid, including water, siloxane, silicic acid, silicic acid derivatives, ammonia, urea, and alkali. The instant sintering aid is used to provide a sintering effect for the sintering process by utilizing the volatility and adhesiveness of the instant sintering aid. It is important that the instant sintering aid completely or partially leaves the product in a short time, plays a role in promoting densification, and finally obtains a dense fracturing material. The entire synthesis process is pollution-free, low-carbon, and environmentally friendly, thereby realizing the green recycling of solid waste-water-based rock cuttings.

[0042] The water-based rock cuttings are divided into two types, A and B. Type A contains Al2O3, and type B contains SiO2. The particle sizes of the water-based rock cuttings of types A and B can be reduced to below 10 μm after grinding.

[0043] The low temperature sintering equipment can provide external conditions for the sintering process, including pressure and temperature, and the pressure and temperature can be controlled and adjusted. The low temperature sintering equipment structure includes a press, a heat preservation device 2, a pressure shaft 3, a sintering chamber 5, an upper pressing plate 6, a lower pressing plate 7, a lead screw 8, an upper pad 9-1, a lower pad 9-2, a sintering tank 10, and a sintering tank pressure shaft 12.

[0044] The insulation device 2 is a heating system surrounding the sintering chamber 5, including but not limited to an electric heating system and a hydrothermal system. It transfers heat to the sintering chamber 5 by heat transfer and can maintain a constant temperature for more than or equal to 2 hours, with a temperature range of 100°C to 200°C. The temperature of the insulation device 2 can be read by a temperature display device, including but not limited to a thermometer, a sensor, and a digital display.

[0045] There is a press machine above the upper pressing plate 6 and below the lower pressing plate 7, which are the upper pressing machine 1-1 and the lower pressing machine 1-2 respectively, and the upper pressing machine 1-1 and the lower pressing machine 1-2 are correspondingly distributed on the surface of the upper pressing plate and the lower pressing plate, which can provide longitudinal (Y-axis) pressure to the pressure shaft 3, and then transmit the pressure to the sintering chamber 5 through the pressure shaft 3, and can maintain a constant pressure for a time greater than or equal to 2 hours, and the pressure range is 100MPa to 500MPa.

[0046] The pressure shaft 3 is a cylindrical component located below the upper pressure plate 6. Its function is to transmit the longitudinal pressure provided by the press to the sintering tank pressure shaft 12. The sintering tank pressure shaft 12 then transmits the pressure to the water-based rock chips in the corresponding sintering tank of the sintering chamber 5. There is a gas channel 11 inside the pressure shaft 3. The inlet of the gas channel 11 is located on the bottom surface of the pressure shaft 3. The outlet of the gas channel 11 is a pressure relief port 4 and is located on the upper side of the pressure shaft 3. The gas channel 11 and the pressure relief port 4 are used to connect and seal the internal pressure of the sintering chamber 5 with the external pressure.

[0047] The pressure relief port 4 is a small hole located on the pressure shaft 3 that can be opened and closed. The opening and closing of the small hole are achieved by nuts and threads or buckles. When the pressure relief port 4 is opened, the internal pressure of the sintering chamber 5 is the same as the external pressure. When the pressure relief port 4 is closed, the internal pressure of the sintering chamber 5 is greater than the external pressure.

[0048] The sintering chamber 5 refers to a component used to realize and complete the sintering process. The sintering chamber 5 completes the sintering process through the pressure and temperature of external conditions and water-based rock chips. A sintering tank is integrated inside the sintering chamber, and the sintering tank is used to hold the water-based rock chips.

[0049] The upper pressure plate 6 is a horizontal structural member, located above the upper pad 9 - 1 , and is longitudinally displaced by the lead screw 8 .

[0050] The lower pressure plate 7 is a horizontal structural member, located below another lower pad 9 - 2 , and is longitudinally displaced by a lead screw 8 .

[0051] The upper pressing plate 6 and the lower pressing plate 7 are connected by a screw rod 8, and the screw rod 8 is used for the upper pressing plate 6 and the lower pressing plate 7 to complete longitudinal displacement.

[0052] The upper pad 9 - 1 is located between the pressure shaft 3 and the upper pressing plate 6 , and is used to fix and protect the pressure shaft 3 . The lower pad 9 - 2 is located between the lower pressing plate 7 and the sintering chamber 5 .

[0053] The sintering tank is a cylindrical hollow structure integrated inside the sintering chamber 5, which is used to hold water-based rock chips and is a space for sintering the water-based rock chips. The horizontal section diameter ranges from 100 μm to 800 μm.

[0054] The gas channel 11 is a single, hollow space integrated inside the pressure shaft 3, whose longitudinal projection cannot fall into the sintering groove and cannot overlap with the sintering groove in any way, and whose diameter or width is less than 100 μm.

[0055] The sintering tank pressure shaft 12 is a cylindrical structure corresponding to the position of the sintering tank. The sintering tank pressure shaft is below the pressure shaft and its function is to transmit the pressure of the pressure shaft 3 to the water-based rock chips in the sintering tank. Its horizontal section diameter ranges from 100μm to 800μm, and the horizontal section diameter is equal to the horizontal section diameter of the sintering tank.

[0056] The sintering process refers to a production process for obtaining a densified fracturing proppant through the low-temperature sintering equipment and the instantaneous sintering aid.

[0057] The mullite phase refers to a phase composition having a whole or part of a mullite structure obtained by low-temperature sintering of water-based rock chips. The condition for sintering to obtain the phase composition of the mullite structure is that the molar ratio of Al2O3 contained in type A to SiO2 contained in type B is less than or equal to 0.5.

[0058] The instantaneous sintering aid refers to a substance that utilizes its volatility and adhesiveness to provide a sintering aid effect for the sintering process. The instantaneous sintering aid completely or partially leaves the product in a short period of time and achieves a densification effect through the sintering process, including one or more of water, siloxane, silicic acid, silicic acid derivatives, ammonia water, urea and alkali.

[0059] Densification refers to the process of aggregating powder particles by sintering to reduce the pores of the powder particles, thereby achieving the purpose of agglomeration. It is usually evaluated by relative density. When the relative density is greater than 0.90, the densification effect is completed.

[0060] The crushing rate refers to the mass percentage of the fracturing material that is crushed under a certain pressure.

[0061] Specifically, the pressure refers to the pressure applied during the sintering process, which is divided into two processes: the first process is the pre-pressurization and reaction process, applying a constant pressure of 100MPa to 500MPa, closing the pressure relief port, maintaining the pressure for more than 2h, and then opening the pressure relief port to release the pressure to the same as the atmospheric pressure; immediately proceeding to the second process, in order to promote the densification process, applying a constant pressure of 100MPa to 500MPa, keeping the pressure relief port open, and maintaining the pressure for more than or equal to 1h, and then stopping the press to remove the pressure; the temperature refers to the pressure applied during the sintering process. The temperature is increased at a rate of 10°C / min to 100°C-200°C, and the temperature is maintained for more than 2 hours; the constant pressure range applied by the press is 100MPa-500Mpa; the constant temperature range provided by the heat preservation device is 100°C-200°C, and the heating rate is 10°C / min; the press can provide longitudinal pressure to the pressure shaft, the sintering tank pressure shaft is below the pressure shaft, and the pressure application is divided into two processes. In the first process, the pressure of the sintering tank pressure shaft is spontaneously generated by the instantaneous sintering aid without contacting the water-based rock chips in the sintering tank In the second process, the pressure spontaneously generated by the instantaneous sintering aid is released through the pressure relief port, and the sintering tank pressure shaft needs to contact the water-based rock chips in the sintering tank; the sintering chamber is integrated with a sintering tank, which is used to hold water-based rock chips, and the sintering tank pressure shaft then transmits the pressure to the water-based rock chips in the corresponding sintering tank of the sintering chamber; the pressure relief port is a small hole located on the pressure shaft that can be opened and closed. When the pressure relief port is opened, the pressure inside the sintering chamber is the same as the outside pressure, and when the pressure relief port is closed, the pressure inside the sintering chamber is greater than the outside pressure. The pressure relief port is closed only in the first pressure application process, and the remaining pressure relief ports are Open state; the heat preservation device is a heating system surrounding the sintering chamber, which transfers heat to the sintering chamber by heat transfer; after maintaining the pressure and temperature for a certain period of time, the pressure is removed and the temperature is naturally lowered to obtain a dense fracturing material with a mullite phase; the instantaneous sintering aid can evaporate rapidly at 90°C to 120°C, or can generate a bonding material at 90°C to 120°C, or can evaporate rapidly at 90°C to 120°C and generate a bonding material; the instantaneous sintering aid, calculated by the mass fraction of the water-based rock cuttings, has an amount of 1% to 4%.

[0062] The present invention provides a method for low-temperature sintering greenly utilizing water-based rock cuttings, comprising the following steps:

[0063] (1) Adjust the upper pressing plate 6, the lower pressing plate 7 and the thread position to keep the low-temperature sintering equipment on a horizontal plane;

[0064] (2) fully mixing a certain amount of type A water-based rock chips and type B water-based rock chips and an instantaneous sintering aid that satisfies the mass ratio according to the ratio of generating mullite phase to obtain a mixture, and then evenly placing the mixture in each sintering tank;

[0065] (3) Close the pressure relief port 4, start the press machine 1, and apply pressure in the longitudinal direction according to the predetermined pressure, and at the same time, turn on the heat preservation device to reach the predetermined temperature, and maintain the pressure and temperature for a certain period of time;

[0066] (4) Adjust the pressure axis to face upward longitudinally so that the pressure axis of the sintering tank does not touch the sintering tank, open the pressure relief port, and wait until the pressure in the sintering chamber is completely released, that is, the pressure is the same as the atmospheric pressure outside the sintering chamber;

[0067] (5) Keep the pressure relief port open, apply pressure in the longitudinal direction according to a predetermined pressure so that the pressure axis of the sintering tank contacts the sintering tank, and maintain the pressure and temperature for a certain period of time;

[0068] (6) Stop the press, remove the pressure and allow the temperature to drop naturally, then take out the sintered product from the sintering tank.

[0069] Example

[0070] The present invention further explains and illustrates the method of low temperature sintering green utilization of water-based rock chips and the beneficial effects brought by the present invention by providing multiple embodiments. Table 1 shows the type A water-based rock chips (containing Al2O3) and type B water-based rock chips (containing SiO2) used in the embodiments.

[0071] Table 1 Composition of type A water-based cuttings and type B water-based cuttings

[0072]

[0073]

[0074] Examples 1 to 4 control a single variable: the instantaneous sintering aid uses water, which plays a volatilizing role in the sintering process. When the temperature is greater than 100°C, water can be effectively volatilized. The pressure of the first process is 500MPa, the temperature is 180°C, and the pressure of the second process is 500MPa, which remain unchanged; what is changed is: the amount of water is 1%, 2%, 3%, and 4% calculated as the mass fraction of water-based rock cuttings; the effects of changing the amount of instantaneous sintering aid on the performance of fracturing materials are illustrated by the examples.

[0075] Example 1

[0076] The sintering process is completed by using low temperature sintering equipment. The schematic diagram of low temperature sintering equipment is as follows: Figures 1 to 4As shown; adjust the upper pressing plate, the lower pressing plate and the thread position, and keep the low-temperature sintering equipment in a horizontal plane; weigh 15kg of type A water-based rock chips and 1kg of type B water-based rock chips, add 1% water to them after fully mixing, the mass of water is 0.16kg, and then fully mix to obtain a mixture, and then the mixture is evenly placed in each sintering tank; close the pressure relief port, start the press, apply a pressure of 500MPa in the longitudinal direction, and at the same time turn on the insulation device to increase the temperature to 180℃ at 10℃ / min, and maintain the pressure and temperature for 3h; adjust the pressure axis to face upward in the longitudinal direction so that the pressure axis of the sintering tank does not contact the sintering tank, open the pressure relief port, wait until the pressure in the sintering chamber is released, that is, the same as the atmospheric pressure outside the sintering chamber, and maintain the temperature at 180℃; keep the pressure relief port open, apply a pressure of 500MPa in the longitudinal direction so that the pressure axis of the sintering tank contacts the sintering tank, and maintain the pressure and temperature for 2h, then stop the press, remove the pressure, stop insulation, and take out the sintered product from the sintering tank after natural cooling.

[0077] Example 2

[0078] The difference between this embodiment and embodiment 1 is that the amount of water used is 2%, i.e. 0.32 kg. The performance results of the obtained samples are shown in Table 2.

[0079] Example 3

[0080] The difference between this embodiment and embodiment 1 is that the amount of water used is 3%, i.e. 0.48 kg. The performance results of the obtained samples are shown in Table 2.

[0081] Example 4

[0082] The difference between this embodiment and embodiment 1 is that the amount of water used is 4%, i.e. 0.64 kg. The performance results of the obtained samples are shown in Table 2.

[0083] Table 2 Performance results of samples of Examples 1 to 4

[0084] Example Relative density Crushing rate (%) 1 0.86 14 2 0.92 8 3 0.96 4 4 0.96 4

[0085] From Examples 1 to 4, it can be seen that increasing the amount of water can increase the relative density of the fracturing material, indicating that its compactness is improved. The increased compactness reduces the crushing rate and effectively improves the surface mechanical properties. In particular, the relative density of the fracturing material obtained in Example 3 reaches 0.96, and the crushing rate is reduced to 4%. This is because under the action of the instantaneous sintering agent, the mullite phase ( Figure 5 and Figure 6 ), after further sintering and removal of the transient sintering aid, a densified fracturing material ( Figure 6 ).from Figure 5It can be seen that the grain size of the sample obtained in Example 3 is about 1 μm, with a dense microstructure and fewer pores, which is consistent with the result of high relative density and helps to reduce the breakage rate. Figure 6 It can be seen that the sample obtained in Example 3 is a mullite phase, and the diffraction peak is sharp, indicating a high degree of crystallization, which helps to improve the mechanical properties of the sample. When the amount of water reaches 4%, the result is the same as that of 3%, so there is no need to increase the amount of water blindly. From the results, it can be seen that when the first process pressure is maintained at 500MPa, the temperature is 180°C, and the second process pressure is 500MPa, when the instantaneous sintering aid is water, its optimal amount is 3% (Example 3).

[0086] Examples 3, 5 to 7 control a single variable: water is used as the instantaneous burning aid, and its dosage is 3%. The first process pressure is 500 MPa, and the second process pressure is 500 MPa, which remain unchanged; what is changed is: the temperature is 160°C, 170°C, 180°C, and 190°C. The effects of changing the temperature on the performance of the fracturing material are explained through the examples.

[0087] Example 5

[0088] The difference between this embodiment and embodiment 3 is that the temperature is 160° C. The performance results of the obtained samples are shown in Table 3.

[0089] Example 6

[0090] The difference between this embodiment and embodiment 3 is that the temperature is 170° C. The performance results of the obtained samples are shown in Table 3.

[0091] Example 7

[0092] The difference between this embodiment and embodiment 3 is that the temperature is 190° C. The performance results of the obtained samples are shown in Table 3.

[0093] Table 3 Performance results of samples of Examples 3, 5 to 7

[0094] Example Relative density Crushing rate (%) 3 0.96 4 5 0.90 10 6 0.92 8 7 0.96 4

[0095] From Examples 3, 5 to 7, it can be seen that increasing the temperature can increase the relative density of the fracturing material, indicating that its compactness is improved. The increased compactness reduces the crushing rate, indicating that the mechanical properties are effectively improved; when the temperature reaches 190°C, the results are the same as those obtained at 180°C, so there is no need to increase the temperature blindly. From the results, it can be seen that the optimal temperature is 180°C when the water dosage is maintained at 3%, the first process pressure is 500MPa, and the second process pressure is 500MPa.

[0096] Examples 3, 8 to 10 control a single variable: water is used as the instantaneous burning aid, and its dosage is 3%. The first process pressure is 500 MPa, the temperature is 180°C, and the second process pressure is 500 MPa, which remain unchanged; what is changed is: the first process pressure holding time is 1h, 2h, 3h, and 4h. The examples illustrate the effect of changing the first process pressure holding time on the performance of the fracturing material.

[0097] Example 8

[0098] The difference between this embodiment and embodiment 3 is that the pressure holding time of the first process is 1 hour. The performance results of the obtained samples are shown in Table 4.

[0099] Example 9

[0100] The difference between this embodiment and embodiment 3 is that the pressure holding time of the first process is 2 hours. The performance results of the obtained samples are shown in Table 4.

[0101] Example 10

[0102] The difference between this embodiment and embodiment 3 is that the pressure holding time of the first process is 4 hours. The performance results of the obtained samples are shown in Table 4.

[0103] Table 4 Performance results of samples of Examples 3, 8 to 10

[0104] Example Relative density Crushing rate (%) 3 0.96 4 8 0.93 7 9 0.95 5 10 0.96 4

[0105] From Examples 3, 8 to 10, it can be seen that extending the first process pressure holding time can increase the relative density of the ceramsite proppant, indicating that its compactness has been improved. The increased compactness reduces the crushing rate, indicating that the mechanical properties have been effectively improved. This is because the first process pressure holding is to generate the mullite phase. Under the action of pressure, temperature and instantaneous sintering agent, extending the time is conducive to the generation of the mullite phase; when the first process pressure holding time is extended to 4h, the result is the same as that obtained by 3h, so there is no need to blindly extend the second process pressure holding time. From the results, it can be seen that it is better to extend the first process pressure holding time to 3h when the water dosage is 3%, the temperature is 110℃, the first process pressure is 500MPa, and the second process pressure is 500MPa.

[0106] Examples 11 to 13 control a single variable: the amount of instantaneous sintering agent is 3%, the pressure of the first process is 500 MPa, the temperature is 180°C, and the pressure of the second process is 500 MPa, which remain unchanged; what is changed is that the instantaneous sintering agent uses siloxane, which are KH570, A171, and silicone oil (polydimethylsiloxane). Siloxane plays a role of volatilization and bonding during the sintering process. When the temperature is greater than 80°C, the siloxane can combine with the surface of the mixed powder B and undergo a condensation reaction. The generated H2O can be effectively volatilized. At the same time, the condensation product remains on the surface of the mixed powder B and plays a bonding role. The two effects jointly promote the densification of ceramsite grains. The examples illustrate the effect of changing the type of instantaneous sintering agent on the performance of fracturing materials.

[0107] Embodiment 11

[0108] The difference between this embodiment and embodiment 3 is that the instantaneous sintering agent is KH570. The performance results of the obtained samples are shown in Table 5.

[0109] Example 12

[0110] The difference between this embodiment and embodiment 3 is that the instantaneous sintering aid is A171. The performance results of the obtained samples are shown in Table 5.

[0111] Embodiment 13

[0112] The difference between this embodiment and embodiment 3 is that the instantaneous sintering aid is silicone oil. The performance results of the obtained samples are shown in Table 5.

[0113] Table 5 Performance results of samples of Examples 11 to 13

[0114] Example Relative density Crushing rate (%) 11 0.98 2 12 0.96 4 13 0.97 3

[0115] It can be seen from Examples 11 to 13 that when the instantaneous sintering aids are all siloxanes, the relative density and crushing rate of the fracturing material are different due to the different molecular structures of different types of siloxanes; because the KH570 molecule has a long chain and unsaturated bonds, the long chain can avoid the influence of the steric hindrance effect on the densification, and the unsaturated bonds are helpful for the polycondensation reaction. The two work together to promote densification, thereby increasing the relative density and reducing the crushing rate; the A171 molecule has no long chain and no unsaturated bonds, which reduces the degree of densification relative to KH570, thereby reducing the relative density and increasing the crushing rate. Silicone oil molecules have long chains but no unsaturated bonds, resulting in the relative density and crushing rate of the fracturing material being in the middle. It can be seen that when the external conditions are the same and the instantaneous sintering aid is an organic matter, the sample performance is mainly affected by whether the instantaneous sintering aid molecules have long chains and unsaturated bonds.

[0116] Examples 14 to 15 control a single variable: the amount of instantaneous sintering aid is 3%, the pressure of the first process is 500 MPa, the temperature is 110°C, and the pressure of the second process is 500 MPa, which remain unchanged; what is changed is that the instantaneous sintering aids are silicic acid and hexyl orthosilicate, respectively; by hydrolysis, silicic acid obtains SiO2 and H2O, and during the sintering process, SiO2 is distributed around the grains (i.e., at the grain boundaries) to fill the gaps, and the generated H2O can be effectively volatilized at a temperature greater than 100°C, and the two effects jointly promote densification; the examples illustrate the effect of changing the type of instantaneous sintering aid on the performance of the fracturing material.

[0117] Example 13

[0118] The difference between this embodiment and embodiment 3 is that the instantaneous sintering aid is silicic acid. The performance results of the obtained samples are shown in Table 6.

[0119] Embodiment 14

[0120] The difference between this embodiment and embodiment 3 is that the instantaneous sintering aid is hexyl orthosilicate. The performance results of the obtained samples are shown in Table 6.

[0121] Table 6 Performance results of samples of Examples 14 to 15

[0122] Example Relative density Crushing rate (%) 14 0.98 2 15 0.99 1

[0123] It can be seen from Examples 14 to 15 that when the instantaneous sintering aid is silicic acid or hexyl orthosilicate, the hydrolysis product SiO2 occupies the position of the pores at the grain boundaries, fills the gaps, and promotes densification, thereby obtaining a fracturing material with a relative density of up to 0.99 and a crushing rate of only 1%.

[0124] Examples 16 to 18 control a single variable: the amount of instantaneous sintering agent is 3%, the pressure of the first process is 500 MPa, the temperature is 110°C, and the pressure of the second process is 500 MPa, which remain unchanged; what is changed is: the instantaneous sintering agent uses ammonia water, urea, and alkali (NaOH is used as an example); the volatilization effect of ammonia water and urea is used to promote densification; the alkali and SiO2 grains can generate an adhesive, and the generated H2O can be effectively volatilized at a temperature greater than 100°C, and the two effects jointly promote grain densification; the examples illustrate the effect of changing the type of instantaneous sintering agent on the performance of the fracturing material.

[0125] Example 16

[0126] The difference between this embodiment and embodiment 3 is that the instantaneous sintering agent is ammonia water. The performance results of the obtained samples are shown in Table 7.

[0127] Embodiment 17

[0128] The difference between this embodiment and embodiment 3 is that the instantaneous burning aid is urea. The performance results of the obtained samples are shown in Table 7.

[0129] Embodiment 18

[0130] The difference between this embodiment and embodiment 3 is that the instantaneous sintering agent is NaOH. The performance results of the obtained samples are shown in Table 7.

[0131] Table 7 Performance results of samples of Examples 16 to 18

[0132] Example Relative density Crushing rate (%) 16 0.97 3 17 0.97 3 18 0.98 2

[0133] It can be seen from Examples 16 to 18 that when the instantaneous sintering aid is ammonia water or urea, the generated NH3 and H2O can be effectively volatilized at a temperature greater than 100°C, thereby promoting grain densification. When the instantaneous sintering aid is NaOH, Na2SiO3 and H2O can be generated around the SiO2 grains. Na2SiO3 is a binder, and H2O can be effectively volatilized at a temperature greater than 100°C. These two effects jointly promote grain densification.

[0134] By comparing the results of the above embodiments, it can be seen that the method for low-temperature sintering and green utilization of water-based rock cuttings provided by the present invention can obtain fracturing materials with a relative density greater than 0.90 and a crushing rate less than 10% below 200°C, which can be used for hydraulic fracturing in oil and gas production. Users can choose a suitable instantaneous sintering aid according to actual needs, such as site, equipment, process, cost, product performance, quality standards and other factors. The present invention greatly reduces the sintering temperature (below 200°C). The entire synthesis process of the present invention is pollution-free, low-energy, low-carbon, and environmentally friendly, thereby realizing low-temperature green recycling of solid waste - water-based rock cuttings, which is conducive to promotion in the field of environmental protection and resource recycling technology and has broad application prospects.

Claims

1. A method for low temperature sintering green utilization of water-based rock cuttings, characterized in that: The method is implemented by using low-temperature sintering equipment; the low-temperature sintering equipment comprises: a heat preservation device (2), an upper press (1-1), a pressure shaft (3), a sintering chamber (5), a sintering tank (10) and a sintering tank pressure shaft (12); The heat preservation device (2) is used to supply heat to the sintering chamber (5) and control the temperature in the sintering chamber (5); the sintering tank (10) is arranged in the sintering chamber (5); A sintering tank pressure shaft (12) is arranged on the bottom surface of the pressure shaft (3), and the sintering tank pressure shaft (12) is adapted to the sintering tank (10); a gas channel (11) is opened inside the pressure shaft (3), the inlet of the gas channel (11) is located on the bottom surface of the pressure shaft (3), and the outlet of the gas channel (11) is a pressure relief port (4) and is located on the side surface of the upper end of the pressure shaft (3); the upper press (1-1) is used to apply downward pressure on the top of the pressure shaft (3); The method specifically comprises: Mixing water-based rock cuttings and an instant sintering aid to obtain a mixture; the instant sintering aid is one or more of water, siloxane, silicic acid, silicic acid derivatives, ammonia water, urea and alkali; The mixture is placed in a sintering tank (10), the pressure shaft (3) is extended into the sintering chamber (5), the pressure relief port (4) is closed, a closed environment is formed in the sintering chamber (5), a downward pressure of 100MPa to 500MPa is applied by an upper press (1-1), and the temperature of the sintering chamber (5) is controlled at 100°C to 200°C by a heat preservation device to perform a low-temperature sintering reaction; After the low-temperature sintering reaction is completed, the upper press (1-1) stops applying pressure and opens the pressure relief port. When the pressure in the sintering chamber (5) drops to atmospheric pressure, the sintering tank pressure shaft (12) contacts the mixture in the sintering tank (10). The upper press (1-1) applies a downward pressure of 100MPa to 500MPa and performs a densification reaction at a temperature of 100°C to 200°C to obtain a fracturing material.

2. The method for low temperature sintering green utilizing water-based rock cuttings according to claim 1, characterized in that: The water-based rock cuttings are a mixture of type A water-based rock cuttings containing Al2O3 and type B water-based rock cuttings containing SiO2.

3. The method for low temperature sintering green utilizing water-based rock cuttings according to claim 2, characterized in that: Type A water-based rock cuttings are calculated as Al2O3, and type B water-based rock cuttings are calculated as SiO2. The molar ratio of type A water-based rock cuttings to type B water-based rock cuttings is less than or equal to 0.

5.

4. The method for low temperature sintering green utilizing water-based rock cuttings according to claim 1, characterized in that: The instantaneous sintering aid accounts for 1% to 4% of the mass of the water-based rock cuttings.

5. The method for low temperature sintering green utilizing water-based rock cuttings according to claim 1, characterized in that: The low-temperature sintering reaction time is 1 to 4 hours.

6. The method for low temperature sintering green utilizing water-based rock cuttings according to claim 1, characterized in that: A plurality of sintering tanks (10) and sintering tank pressure shafts (12) are provided, and the sintering tank pressure shafts (12) correspond one to one with the sintering tanks (10).

7. The method for low temperature sintering green utilizing water-based rock cuttings according to claim 1, characterized in that: The low-temperature sintering equipment further comprises: an upper pressing plate (6), a lower pressing plate (7), an upper pad (9-1), a lower pad (9-2) and a lead screw (8); The sintering chamber (5) is arranged on the top of the lower pad (9-2), the lower pad (9-2) is arranged on the top of the lower pressing plate (7), the upper pad (9-1) is arranged on the top of the pressure shaft (3), the upper pressing plate (6) is arranged on the top of the upper pad (9-1), and the upper pressing plate (6) and the lower pressing plate (7) are connected by a lead screw (8); The upper pad (9-1) is connected to the upper pressing plate (6) and is connected to the top of the upper pad (9-1), the upper press (1-1) applies downward pressure to the top of the upper pressing plate (6), and the lower press (1-2) applies upward pressure to the bottom of the lower pressing plate (7).

8. A low temperature sintering device, characterized in that: include: A heat preservation device (2), an upper press (1-1), a pressure shaft (3), a sintering chamber (5), a sintering tank (10) and a sintering tank pressure shaft (12); The heat preservation device (2) is used to supply heat to the sintering chamber (5) and control the temperature in the sintering chamber (5); the sintering tank (10) is arranged in the sintering chamber (5); A sintering tank pressure shaft (12) is arranged on the bottom surface of the pressure shaft (3), and the sintering tank pressure shaft (12) is adapted to the sintering tank (10); a gas channel (11) is opened inside the pressure shaft (3), the inlet of the gas channel (11) is located on the bottom surface of the pressure shaft (3), and the outlet of the gas channel (11) is a pressure relief port (4) and is located on the upper side of the pressure shaft (3); the upper press (1-1) is used to apply downward pressure on the top of the pressure shaft (3).

9. The low temperature sintering equipment according to claim 8, characterized in that: A plurality of sintering tanks (10) and sintering tank pressure shafts (12) are provided, and the sintering tank pressure shafts (12) correspond one to one with the sintering tanks (10).

10. The low temperature sintering equipment according to claim 8, characterized in that: Also includes: An upper pressing plate (6), a lower pressing plate (7), an upper pad (9-1), a lower pad (9-2) and a lead screw (8); The sintering chamber (5) is arranged on the top of the lower pad (9-2), the lower pad (9-2) is arranged on the top of the lower pressing plate (7), the upper pad (9-1) is arranged on the top of the pressure shaft (3), the upper pressing plate (6) is arranged on the top of the upper pad (9-1), and the upper pressing plate (6) and the lower pressing plate (7) are connected by a lead screw (8); The upper pad (9-1) is connected to the upper pressing plate (6) and is connected to the top of the upper pad (9-1), the upper press (1-1) applies downward pressure to the top of the upper pressing plate (6), and the lower press (1-2) applies upward pressure to the bottom of the lower pressing plate (7).

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