A method and system for treating spent water-based drilling fluids

Abstract

The present application relates to the technical field of waste water-based drilling fluid processing, and particularly relates to a waste water-based drilling fluid processing method and system, the method comprising the following steps: filtering the waste water-based drilling fluid, and preheating the filtered waste water-based drilling fluid; heating and evaporating the preheated waste water-based drilling fluid, and simultaneously performing centrifugal separation to obtain thick liquid, recovered liquid and steam; the thick liquid is separated again by extrusion to obtain liquid phase and solid phase, the recovered liquid and steam are used for heat exchange with the filtered waste water-based drilling fluid to complete the preheating of the filtered waste water-based drilling fluid, and finally the heat-exchanged liquid is recovered for preparing drilling fluid; the system comprises a filtering device, a heat exchange assembly, a heating and separating device, an extrusion device and a collection tank. Through the processing method and system, the water containing beneficial additives can be recycled and the energy consumption is low.

Description

Technical Field

[0001] This invention relates to the field of waste water-based drilling fluid treatment technology, and in particular to a method and system for treating waste water-based drilling fluid. Background Technology

[0002] During drilling, water-based drilling fluid is processed through a vibrating screen and centrifuge, and then further reduced in volume using a spin dryer or filter press. However, drilling fluid treated with a spin dryer has a high solids content and cannot be used to prepare water-based drilling fluid, resulting in a large amount of waste drilling fluid remaining. On the other hand, using a filter press generally requires the addition of demulsifiers and flocculants, which not only wastes materials but also makes it difficult to prepare water-based drilling fluid again.

[0003] Existing technologies also propose treating waste drilling fluid through evaporation and crystallization. However, this method is energy-intensive and cannot retain beneficial additives such as viscosifiers in waste water-based drilling fluid, making it impossible to recycle these beneficial additives. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention proposes a method and system for treating waste water-based drilling fluid, which not only enables the recycling of water containing beneficial additives but also consumes little energy.

[0005] This invention is achieved by adopting the following technical solution:

[0006] A method for treating waste water-based drilling fluid includes the following steps:

[0007] Step S1. Coarsely filter the waste water-based drilling fluid and preheat the coarsely filtered waste water-based drilling fluid;

[0008] Step S2. The preheated waste water-based drilling fluid is heated and evaporated, and centrifuged to obtain thick liquid, recovered liquid and steam.

[0009] Step S3. The thick liquid is squeezed and separated again to obtain a liquid phase and a solid phase. The liquid phase is used to be introduced into the waste water-based drilling fluid in step S1. The recovered liquid and steam are used to exchange heat with the coarsely filtered waste water-based drilling fluid in step S1 to complete the preheating treatment of the coarsely filtered waste water-based drilling fluid. Finally, the liquid after heat exchange is recovered and used to prepare drilling fluid.

[0010] The preheating treatment in step S1 specifically refers to passing the coarsely filtered waste water-based drilling fluid through a first-stage heat exchange treatment, a second-stage heat exchange treatment, and a third-stage heat exchange treatment in sequence.

[0011] The use of recovered liquid and steam for heat exchange with the coarsely filtered waste water-based drilling fluid in step S1 specifically refers to: the steam and recovered liquid generated in step S2 exchange heat with the waste water-based drilling fluid in the secondary heat exchange treatment to generate secondary steam; the secondary steam exchanges heat with the waste water-based drilling fluid in the tertiary heat exchange treatment; the excess steam after heat exchange is connected to the atmosphere; the condensate after heat exchange exchanges heat with the waste water-based drilling fluid in the secondary heat exchange treatment and the waste water-based drilling fluid in the primary heat exchange treatment in sequence, and then recovers it.

[0012] In step S2, the heating temperature is 125±20℃, and the centrifugal speed is 750-1500r / min.

[0013] By adjusting the amount of waste water-based drilling fluid treated and the heating temperature, a dynamic balance is maintained.

[0014] A waste water-based drilling fluid treatment system includes a filtration device, a heat exchange assembly, a heating and separation device, a squeezing device, and a collection tank. The filtration device is used for coarse filtration of the waste water-based drilling fluid. The heat exchange assembly is used to exchange heat with the coarsely filtered waste water-based drilling fluid and then pass it into the heating and separation device. The heating and separation device is used to heat and evaporate the heat-exchanged waste water-based drilling fluid while simultaneously centrifuging it to obtain a viscous liquid, a recovered liquid, and steam. The squeezing device is used to further separate the viscous liquid to obtain a solid phase and a liquid phase for passing into the filtration device. The recovered liquid and steam are passed into the heat exchange assembly for heat exchange with the coarsely filtered waste water-based drilling fluid.

[0015] The heat exchange assembly includes a primary heat exchanger, a secondary heat exchanger, and a tertiary heat exchanger connected in sequence.

[0016] The primary, secondary, and tertiary heat exchangers are also equipped with insulation layers.

[0017] The hot fluid inlet of the secondary heat exchanger is connected to the recovery liquid outlet of the heating and separation equipment, the steam outlet of the heating and separation equipment, and the hot fluid outlet of the tertiary heat exchanger; the hot fluid inlet of the tertiary heat exchanger is connected to the steam outlet of the secondary heat exchanger; the hot fluid inlet of the primary heat exchanger is connected to the hot fluid outlet of the secondary heat exchanger, and the hot fluid outlet of the primary heat exchanger is connected to the collection box.

[0018] The filtration device is installed in the compartment of the collection box.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] 1. This method eliminates the need to add a breaker during the process, and the recovered fluid is readily available for re-preparation of drilling fluid.

[0021] This method employs a combination of partial evaporation and partial heating centrifugation for solid-liquid separation. This reduces the viscosity of the thickening agent, facilitating rapid separation of harmful solid and liquid phases. In application, its energy consumption is an order of magnitude lower than direct evaporation. More importantly, this method maximizes the retention of beneficial components in the recovered liquid, such as the thickening agent, for reuse. Furthermore, this method utilizes atmospheric pressure heating separation, making it more economically suitable for industrial applications.

[0022] 2. This invention employs multiple heat exchange processes, enabling waste heat utilization and resulting in low energy consumption during the treatment process. Furthermore, in this invention, the generated recovered liquid and steam are used for heat exchange with the waste water-based drilling fluid in the secondary heat exchange treatment, resulting in more thorough steam cooling and higher heat utilization efficiency. Additionally, the excess steam after heat exchange in the tertiary heat exchange treatment is connected to the atmosphere, preventing excessive pressure during the heat exchange process.

[0023] 3. Through this system, the heating separation equipment can evaporate part of the liquid phase and then condense it to keep the corresponding recovery liquid conveying pipeline clean and ensure process continuity.

[0024] 4. In this system, the primary heat exchanger, secondary heat exchanger and tertiary heat exchanger are also provided with an insulation layer, which can reduce heat loss.

[0025] 5. In this invention, the filtration device is installed in the partition of the collection box, which facilitates increasing the flow area and makes it less prone to clogging. Attached Figure Description

[0026] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments, wherein:

[0027] Figure 1 This is a schematic diagram of the structure of the present invention;

[0028] Marked in the image:

[0029] 1. Collection box; 2. Primary heat exchanger; 3. Secondary heat exchanger; 4. Tertiary heat exchanger; 5. Heating and separation equipment; 6. Extrusion device. Detailed Implementation

[0030] Example 1

[0031] As a basic embodiment of the present invention, the present invention includes a method for treating waste water-based drilling fluid, comprising the following steps:

[0032] Step S1. Coarsely filter the waste water-based drilling fluid and preheat the coarsely filtered waste water-based drilling fluid.

[0033] Step S2. The preheated waste water-based drilling fluid is heated and evaporated, and then centrifuged to obtain viscous liquid, recovered liquid and steam.

[0034] Step S3. The viscous liquid is further separated by extrusion to obtain a liquid phase and a solid phase. The liquid phase is used to introduce the waste water-based drilling fluid from step S1, and the solid phase can be used as an industrial raw material. The recovered liquid and steam are used to exchange heat with the coarsely filtered waste water-based drilling fluid from step S1 to preheat the coarsely filtered waste water-based drilling fluid. Finally, the liquid after heat exchange is recovered and used to prepare drilling fluid.

[0035] Example 2

[0036] In a preferred embodiment of the present invention, the present invention includes a method for treating waste water-based drilling fluid, comprising the following steps:

[0037] Step S1. Coarsely filter the waste water-based drilling fluid and preheat the coarsely filtered waste water-based drilling fluid.

[0038] Step S2. The preheated waste water-based drilling fluid is heated and evaporated, and then centrifuged to obtain viscous liquid, recovered liquid and steam.

[0039] Step S3. The viscous liquid is squeezed and separated again to obtain a liquid phase and a solid phase. The liquid phase is used to be introduced into the waste water-based drilling fluid in step S1.

[0040] The recovered liquid and steam are used to exchange heat with the coarsely filtered waste water-based drilling fluid in step S1, completing the preheating treatment of the coarsely filtered waste water-based drilling fluid. Finally, the liquid after heat exchange is recovered for the preparation of drilling fluid. Specifically, the coarsely filtered waste water-based drilling fluid is sequentially subjected to primary, secondary, and tertiary heat exchange treatments. The steam and recovered liquid generated in step S2 are used to exchange heat with the waste water-based drilling fluid in the tertiary heat exchange treatment. The condensed liquid after heat exchange is sequentially exchanged heat with the waste water-based drilling fluid in the secondary and primary heat exchange treatments, and then recovered. Excess steam in the tertiary heat exchange treatment can be discharged into the atmosphere to avoid pressure buildup and ensure production safety.

[0041] Example 3

[0042] In another preferred embodiment of the present invention, the present invention includes a method for treating waste water-based drilling fluid, comprising the following steps:

[0043] Step S1. Coarsely filter the waste water-based drilling fluid and preheat the coarsely filtered waste water-based drilling fluid.

[0044] Step S2. The preheated waste water-based drilling fluid is heated and evaporated, and then centrifuged to obtain viscous liquid, recovered liquid and steam.

[0045] Step S3. The viscous liquid is further separated by compression to obtain a liquid phase and a solid phase. The liquid phase is used to introduce the waste water-based drilling fluid from step S1. The recovered liquid and steam are used to exchange heat with the coarsely filtered waste water-based drilling fluid from step S1 to preheat the coarsely filtered waste water-based drilling fluid. Finally, the recovered liquid after heat exchange is recovered and used to prepare the drilling fluid.

[0046] Specifically, the preheating treatment in step S1 refers to subjecting the coarsely filtered waste water-based drilling fluid to primary, secondary, and tertiary heat exchange treatments. Specifically, the steam and recovered liquid generated in step S2 exchange heat with the waste water-based drilling fluid in the secondary heat exchange treatment, generating secondary steam. This secondary steam then exchanges heat with the waste water-based drilling fluid in the tertiary heat exchange treatment. Excess steam after heat exchange is released into the atmosphere. The condensate after heat exchange exchanges heat with the waste water-based drilling fluid in both the secondary and primary heat exchange treatments before being recycled.

[0047] Example 4

[0048] In another preferred embodiment of the present invention, the present invention includes a waste water-based drilling fluid treatment system, comprising a filtration device, a heat exchange assembly, a heating and separation device 5, a squeezing device 6, and a collection tank 1. The filtration device is used for coarse filtration of the waste water-based drilling fluid. The heat exchange assembly is used to exchange heat with the coarsely filtered waste water-based drilling fluid and then introduce it into the heating and separation device 5. The heating and separation device 5 is used to heat and evaporate the heat-exchanged waste water-based drilling fluid while simultaneously performing centrifugal separation to obtain a viscous liquid, a recovered liquid, and steam. The squeezing device 6 is used to further separate the viscous liquid to obtain a solid phase and a liquid phase for introduction into the filtration device. The recovered liquid and steam are introduced into the heat exchange assembly for heat exchange with the coarsely filtered waste water-based drilling fluid.

[0049] Example 5

[0050] As the preferred embodiment of the present invention, please refer to the appendix to the specification. Figure 1This invention includes a waste water-based drilling fluid treatment system, comprising a filtration device, a heat exchange assembly, a heating and separation device 5, a squeezing device 6, and a collection tank 1. The heat exchange assembly includes a primary heat exchanger 2, a secondary heat exchanger 3, and a tertiary heat exchanger 4 connected in sequence. Furthermore, the primary heat exchanger 2, secondary heat exchanger 3, and tertiary heat exchanger 4 are equipped with an insulation layer to reduce heat loss. The heating and separation device 5 is an atmospheric pressure heating and separation device, including a centrifugal separator and a heating source located outside the centrifugal separator. The filtration device is disposed in a partition of the collection tank 1.

[0051] Specifically, the outlet of the filtration device is connected to the cold fluid inlet of the first-stage heat exchanger 2 via a first pipe, and a pump is also installed on the first pipe. The cold fluid outlet of the first-stage heat exchanger 2 is connected to the cold fluid inlet of the second-stage heat exchanger 3 via a pipe, the cold fluid outlet of the second-stage heat exchanger 3 is connected to the cold fluid inlet of the third-stage heat exchanger 4 via a pipe, and the cold fluid outlet of the third-stage heat exchanger 4 is connected to the inlet of the heating and separation device 5 via a pipe.

[0052] The steam outlet and the recovered liquid outlet of the heating and separation device 5 are respectively connected to the hot fluid inlet of the secondary heat exchanger 3 via pipelines. The steam outlet of the secondary heat exchanger 3 is connected to the hot fluid inlet of the tertiary heat exchanger 4, and the hot fluid outlet of the tertiary heat exchanger 4 is also connected to the hot fluid inlet of the secondary heat exchanger 3. The hot fluid outlet of the secondary heat exchanger 3 is connected to the hot fluid inlet of the primary heat exchanger 2 via a pipeline, and the hot fluid outlet of the primary heat exchanger 2 is connected to the collection tank 1 via a pipeline.

[0053] The viscous liquid outlet of the heating separation device 5 is connected to the inlet of the extrusion device 6 via a pipe, and the liquid phase outlet of the extrusion device 6 is connected to the inlet of the filtration device via a pipe; the solid phase outlet of the extrusion device 6 is used to collect the solid phase and then send it out.

[0054] A method for treating waste water-based drilling fluid, based on the aforementioned treatment system, includes the following steps:

[0055] Step S1. The coarsely filtered waste water-based drilling fluid, hereinafter referred to as waste fluid, is pumped through a primary heat exchanger 2, a secondary heat exchanger 3, and a tertiary heat exchanger 4 before being transported to a heating and separation device 5.

[0056] Specifically, the waste liquid enters the filtration equipment through the inlet of the filtration equipment. After coarse filtration, the waste liquid is pumped from the outlet of the filtration equipment to the cold fluid inlet of the first-stage heat exchanger 2. After heat exchange, it flows from the cold fluid inlet of the first-stage heat exchanger 2 to the cold fluid inlet of the second-stage heat exchanger 3. After heat exchange again, it flows from the cold fluid outlet of the second-stage heat exchanger 3 to the cold fluid inlet of the third-stage heat exchanger 4. After heat exchange again, it enters the heating and separation equipment 5 through the inlet of the heating and separation equipment 5.

[0057] Step S2. The waste liquid introduced into the heating separation device 5 is heated and evaporated, while simultaneously centrifuged. During centrifugation, the rotation speed is generally controlled at 750-1500 r / min, and the heating temperature is controlled at 125±20℃. After processing by the heating separation device 5, high-temperature recovered liquid, steam, and high-temperature viscous liquid are obtained.

[0058] Step S3. The high-temperature viscous liquid enters the extrusion device 6 through the viscous liquid outlet of the heating separation device 5 and the inlet of the extrusion device 6. After extrusion, it is separated again to obtain a high-temperature liquid phase and a solid phase. The high-temperature liquid phase is used to enter the filtration device through the inlet of the filtration device, and the solid phase can be sent out after cooling as an industrial raw material.

[0059] The high-temperature recovered liquid and steam after centrifugal separation enter the secondary heat exchanger 3 through the steam outlet and recovered liquid outlet of the corresponding heating and separation device 5 and the hot fluid inlet of the secondary heat exchanger 3. There, they exchange heat with the waste liquid from the secondary heat exchange process, preheating the waste liquid. The steam, after heat exchange with the waste liquid in the secondary heat exchanger 3, enters the tertiary heat exchanger 4, where it exchanges heat with the waste liquid from the tertiary heat exchange process, preheating and maintaining the temperature of the waste liquid. The high-temperature water condensed after heat exchange in the tertiary heat exchanger 4 exchanges heat sequentially with the waste liquid in the secondary heat exchanger 3 and the waste liquid in the primary heat exchanger 2, successively obtaining the corresponding high-temperature recovered liquid and medium-low temperature recovered liquid. Finally, it flows into the collection tank 1 for reuse in the preparation of drilling fluid.

[0060] Among them, the small amount of steam generated in the third-stage heat exchanger 4 can be discharged to the outside through the steam outlet of the third-stage heat exchanger 4 to avoid pressure buildup and ensure production safety.

[0061] Furthermore, this embodiment maintains a dynamic balance by adjusting the waste water-based drilling fluid treatment volume and heating temperature. Specifically, during operation, a certain treatment volume and temperature are set. When the temperature rises, the heating power is reduced. For example, if the heating power is reduced to 60% of the rated power but the temperature continues to rise, the treatment volume is increased. When the temperature drops, the heating power is increased; when the heating power reaches 90% of the full load but the temperature continues to drop, the treatment volume is reduced.

[0062] In summary, any other corresponding modifications made by those skilled in the art after reading this invention document, without requiring creative mental effort, based on the technical solutions and concepts of this invention, are all within the scope of protection of this invention.

Claims

1. A method for treating waste water-based drilling fluid, characterized in that: Includes the following steps: Step S1. Coarsely filter the waste water-based drilling fluid and preheat the coarsely filtered waste water-based drilling fluid; Step S2. The preheated waste water-based drilling fluid is heated and evaporated, and centrifuged at the same time. That is, solid-liquid separation is carried out by combining partial evaporation and partial heating and centrifugation to obtain viscous liquid, recovered liquid and steam. The heating temperature is 125℃±20℃, and the centrifugation speed is 750r / min-1500r / min. Step S3. The thick liquid is squeezed and separated again to obtain a liquid phase and a solid phase. The liquid phase is used to be introduced into the waste water-based drilling fluid in step S1. The recovered liquid and steam are used to exchange heat with the coarsely filtered waste water-based drilling fluid in step S1 to complete the preheating treatment of the coarsely filtered waste water-based drilling fluid. Finally, the liquid after heat exchange is recovered and used to prepare drilling fluid.

2. The method for treating waste water-based drilling fluid according to claim 1, characterized in that: The preheating treatment in step S1 specifically refers to passing the coarsely filtered waste water-based drilling fluid through a first-stage heat exchange treatment, a second-stage heat exchange treatment, and a third-stage heat exchange treatment in sequence.

3. The method for treating waste water-based drilling fluid according to claim 2, characterized in that: The use of recovered liquid and steam for heat exchange with the coarsely filtered waste water-based drilling fluid in step S1 specifically refers to: the steam and recovered liquid generated in step S2 exchange heat with the waste water-based drilling fluid in the secondary heat exchange treatment to generate secondary steam; the secondary steam exchanges heat with the waste water-based drilling fluid in the tertiary heat exchange treatment; the excess steam after heat exchange is connected to the atmosphere; the condensate after heat exchange exchanges heat with the waste water-based drilling fluid in the secondary heat exchange treatment and the waste water-based drilling fluid in the primary heat exchange treatment in sequence, and then recovers it.

4. The method for treating waste water-based drilling fluid according to claim 1, characterized in that: By adjusting the amount of waste water-based drilling fluid treated and the heating temperature, a dynamic balance is maintained.

5. A waste water-based drilling fluid treatment system, characterized in that: The system includes a filtration device, a heat exchange assembly, a heating and separation device (5), a squeezing device (6), and a collection tank (1). The filtration device is used for coarse filtration of waste water-based drilling fluid. The heat exchange assembly is used to exchange heat with the coarsely filtered waste water-based drilling fluid and then pass it into the heating and separation device (5). The heating and separation device (5) is used to heat and evaporate the heat-exchanged waste water-based drilling fluid while centrifuging to obtain a thick liquid, a recovered liquid, and steam. The squeezing device (6) is used to further separate the thick liquid to obtain a solid phase and a liquid phase for passing into the filtration device. The recovered liquid and steam are passed into the heat exchange assembly to exchange heat with the coarsely filtered waste water-based drilling fluid. The heating temperature of the heating and separation device (5) is 125℃±20℃, and the centrifugal speed is 750r / min-1500r / min.

6. The waste water-based drilling fluid treatment system according to claim 5, characterized in that: The heat exchange assembly includes a primary heat exchanger (2), a secondary heat exchanger (3), and a tertiary heat exchanger (4) connected in sequence.

7. The waste water-based drilling fluid treatment system according to claim 6, characterized in that: The primary heat exchanger (2), secondary heat exchanger (3) and tertiary heat exchanger (4) are also provided with an insulation layer.

8. A waste water-based drilling fluid treatment system according to claim 6 or 7, characterized in that: The hot fluid inlet of the secondary heat exchanger (3) is connected to the recovery liquid outlet of the heating and separation device (5), the steam outlet of the heating and separation device (5), and the hot fluid outlet of the tertiary heat exchanger (4); the hot fluid inlet of the tertiary heat exchanger (4) is connected to the steam outlet of the secondary heat exchanger (3); the hot fluid inlet of the primary heat exchanger (2) is connected to the hot fluid outlet of the secondary heat exchanger (3), and the hot fluid outlet of the primary heat exchanger (2) is connected to the collection box (1).

9. A waste water-based drilling fluid treatment system according to claim 5, characterized in that: The filtration device is installed in the compartment of the collection box (1).

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