CN117566946A - An electrocatalytic treatment method and treatment system for oilfield drilling wastewater - Google Patents

Abstract

The invention provides an electrocatalytic treatment method and treatment system for oilfield drilling wastewater. The electrocatalytic treatment method for oilfield drilling wastewater includes the following steps: (1) coagulation treatment; (2) electrocatalytic oxidation treatment: electrocatalytic oxidation treatment is performed on the wastewater after coagulation treatment; (3) solid-liquid separation treatment: The wastewater treated by electrocatalytic oxidation is separated after standing. This treatment method can achieve gel breaking and destabilization of drilling wastewater in a short period of time, effectively remove suspended solids SS and oil in the wastewater, and reduce the median particle size of the particles; the pH change range is small. In addition, it also has good removal effect on COD and ammonia nitrogen. By adjusting the process parameters and the number of plates, the quality of the effluent can be further improved; and the treatment energy consumption can be effectively controlled; it is a method to achieve efficient reinjection of drilling wastewater.

Description

An electrocatalytic treatment method and treatment system for oilfield drilling wastewater

Technical field

The invention belongs to the technical field of oil and gas field wastewater treatment, and specifically relates to an electrocatalytic treatment method and treatment system for oilfield drilling wastewater.

Background technique

With the development of the economy, the demand for petroleum energy is increasing day by day. Therefore, effective treatment of wastewater generated during oil and gas exploration and production has become the key to green production and sustainable development of the petroleum and petrochemical industry. During the drilling and workover operations in oil and gas fields, drilling wastewater containing a large amount of oil, organic polymers, heavy metals, colloids and other pollutants will be produced. This wastewater has complex components, is highly polluting, and is difficult to degrade. Drilling wastewater mainly consists of waste drilling fluid, drilling cuttings, well washing water and water for flushing equipment. At present, oilfield wastewater treatment processes are mainly divided into three methods: reinjection, resource reuse and standard discharge treatment. Considering the water consumption and secondary pollution problems of discharge treatment, from the perspective of cost and environmental protection , the reuse or reinjection of drilling wastewater are the future development trends of the oilfield industry.

The reuse or reinjection of drilling wastewater mainly involves the removal of suspended components in the water. Theoretically, methods for removing suspended components mainly include chemical methods and physical methods. The most commonly used chemical method is the coagulation precipitation method, that is, by adding aluminum salts and iron salts (usually inorganic polymer salts are used, including polyaluminum chloride, polyferric sulfate, etc.) through compression of the electric double layer, adsorption bridging, etc. The reaction process causes the pollutants in the water to destabilize, condense and settle. Colloidal pollutants in water usually have negative charges. The colloidal particles repel each other to form a stable mixed solution. Adding an electrolyte with opposite charges (i.e., coagulant) can change the colloidal particles in sewage to electrical neutrality. , and condense into large particles to settle under the action of molecular gravity, achieving solid-liquid separation. Physical laws include methods such as precipitation, screening, flotation, and centrifugation. As an emerging industrial treatment method, ceramic membrane filtration is a physical screening (retention) method. The principle is to use ceramic membrane filtration pores to intercept suspended solids to achieve solid-liquid separation.

However, there are many challenges in practical application of these methods that are difficult to completely solve. For example, the chemical flocculant added in the chemical flocculation method does not completely enter the floc layer. Usually the volume of floc accounts for 15-50% of the entire liquid. It is necessary to use a high-mesh filter cloth for solid-liquid separation to meet the standards for reinjection of water. However, Such treatment has the problem of filter hole clogging, and it is difficult to remove fine clay suspended particles, oil, heavy metal ions and soluble treatment agents in drilling wastewater. In ceramic membrane filtration, although it is usually achieved by pressure difference, continuous backwashing is required during use to prevent clogging, and depending on the reinjection water quality requirements, multiple filtrations may be required to meet the standards. At the same time, the concentrated water with high suspended solids (about 20-25%) is still in a stable emulsion state, and a better treatment solution has not yet been found.

Therefore, facing the needs of oil and gas field development and the current situation of suspended solids removal methods, it is a top priority for scientific and technological workers to seek better suspended solids removal solutions.

CN211813593U discloses an electrolysis air flotation device for oily wastewater, which is used for oily water treatment in petrochemical industry and machinery manufacturing. The electrolytic air flotation method uses electrolysis to generate tiny bubbles required for air flotation, adhering to the suspended substances and colloidal particles in the sewage to float up until they reach the liquid surface and are scraped off. The microbubbles produced by electrolytic air flotation are smaller than those produced by dissolved air flotation and aeration air flotation. The air flotation treatment efficiency is high, the operating conditions are easy to control, and it is safe and reliable. It includes an air flotation cylinder and an electrolysis system; a centrifugal agitator is provided above the interior of the air flotation cylinder, and the centrifugal agitator is connected to a reducer installed on the top of the air flotation cylinder; a slag collecting device is provided on the upper side of the centrifugal mixer; the electrolysis system includes an anode Electrode plate, cathode electrode plate, high-frequency DC power supply, the anode electrode plate and the cathode electrode plate are respectively installed on the upper inner wall of the air floatation cylinder body, the high-frequency DC power supply is arranged on the outside of the air floatation cylinder body, and the high-frequency DC power supply is electrically connected to the anode electrode plate and the cathode electrode plate. Cathode electrode plate; a water distribution device is provided at the lower part of the air flotation cylinder, and a water inlet pipe is provided below the outside of the air flotation cylinder, and the water distribution device is connected to the water inlet pipe. The electrolysis air flotation device uses graphite electrode plates to form electrode components.

However, this technical solution: 1. Treat oily wastewater mainly from production activities in petrochemical and machinery manufacturing processes, such as machine cleaning, processing and chemical reaction processes. The chemicals usually contained in these wastewater are lubricating oil, metal particles, cleaning 2. Graphite is used as the anode plate and cathode plate. As the active plate of electrolysis, it basically has no electrocatalytic activity, which is not conducive to the generation of hydroxyl radicals and indirect oxidation. It has a poor mineralization effect on organic particles. Poor, it is not conducive to the destabilization of colloids and the demulsification of oily wastewater; 3. The cost of graphite cathode plates is relatively high, and stainless steel plates can be replaced in industrial applications. In the treatment of oily wastewater, a higher potential can achieve effective catalytic reaction, and too high a potential will also lead to an increase in energy consumption; 4. This technical solution removes suspended solids through microbubble flotation, but has little effect on the removal of COD and ammonia nitrogen. Not ideal.

CN111825251A discloses a drilling wastewater treatment device and method. The drilling wastewater treatment device includes: an electroflocculation reaction tank, an electrooxidation reaction tank and an inclined plate settling tank that are connected in sequence. The combined electrocoagulation-electrooxidation process is used to remove pollutants such as hardness ions, suspended solids, organic matter, and sulfate-reducing bacteria. This technical solution utilizes the reaction mechanism of chlorine radicals present in drilling wastewater and electro-oxidation, and has a certain bactericidal effect without adding additional chemicals. The main step is to use a lifting device to lift the drilling wastewater to the electroflocculation reaction. The drilling wastewater passes through the electrolysis reaction zone, reacts with the iron ions electrolyzed by the electrode plates, and flushes the electrode plates at the same time; the drilling wastewater then enters the flocculation and sedimentation zone, and the flocs aggregate and precipitate; the drilling wastewater undergoes electroflocculation After treatment in the reaction tank, it enters the electro-oxidation reaction tank for electro-oxidation treatment. The dosing pump adds hydrochloric acid to adjust the pH value in the tank. The aeration pipeline at the bottom of the tank performs pure oxygen aeration; the drilling after electro-oxidation treatment The wastewater enters the inclined plate settling tank to complete the settlement and separation of flocs.

This technical solution: 1. The treatment target is shale gas drilling wastewater; shale gas extraction usually relies on hydraulic fracturing technology, which uses a large amount of water and chemical additives, which will affect the composition of the wastewater. In contrast, drilling activities in traditional oil fields do not rely on hydraulic fracturing, so the composition of their wastewater is different from that of shale gas drilling wastewater; 2. This technical solution requires the establishment of multiple electrochemical reaction cells, through the addition of additional catalytic Particles, pure oxygen aeration for graded treatment, setting up an automatic pump and adding hydrochloric acid to adjust the pH, the process is complex, it occupies a large area, and the operating cost is high; 3. The ruthenium-titanium alloy used in the electrocatalytic anode plate, the oxygen evolution potential of the electrode Low, it is an active electrode with weak indirect oxidation ability. The electrode often undergoes direct oxidation, and the oxidation and decomposition of organic matter is not ideal. The SS after treatment is greater than 50mg/L, and the COD is greater than 300mg/L, which is far from reaching Criteria for re-injection.

CN110510710 A discloses an integrated electrocoagulation and electrocatalytic oxidation wastewater treatment device, which is used to treat wastewater with high salt content, high COD, high suspended solids, and excessive heavy metal ions produced in industries such as printing and dyeing, papermaking, chemicals, and pesticides. The core part of the device is a reaction tank, which is divided into two parts: the electroflocculation reaction chamber and the electrocatalytic reaction chamber. The wastewater first enters the electroflocculation reaction chamber through the water inlet pipe on the side wall, where the electrode group helps remove suspended solids. There is a slag collection chamber on one side of the reaction chamber, with a slag scraper and slag discharge pipe above it to remove sludge. There is a mud discharge pipe at the bottom of the electrocoagulation reaction chamber for settling and discharging sediment. The wastewater then flows into the electrocatalytic reaction chamber, where the water flow is guided through a rectifying plate, and an electrocatalytic oxidation electrode group is installed in the middle to further degrade pollutants. There is also a settling tank at the bottom of the electrocatalytic reaction chamber for collecting and discharging sediment. Finally, the treated water passes through the water outlet water collecting cavity separated by the second partition, and then is discharged from the water outlet pipe on the side wall.

This technical solution: 1. The treatment targets are relatively simple wastewater such as printing and dyeing, papermaking, chemical industry and pesticide wastewater; 2. The electrocatalytic anode plate uses ruthenium-titanium alloy material, which has a low oxygen evolution potential, making the electrode It shows high activity, but its ability in indirect oxidation is relatively weak, causing the electrode to mainly perform direct oxidation, which means that the oxidative decomposition effect of organic matter is not satisfactory, especially when dealing with some complex materials. organic matter, it may not be as efficient as expected.

Contents of the invention

In order to solve the above problems, the present invention provides an efficient and low-cost electrocatalytic treatment method and treatment system for oilfield drilling wastewater. This method can achieve gel breaking and destabilization of drilling wastewater in a short period of time, and can effectively treat SS and oil. The removal rate is high and the median particle size is reduced; the pH change range is small.

In order to achieve the above objectives, the present invention provides an electrocatalytic treatment method for oilfield drilling wastewater, which includes the following steps:

(1) Coagulation treatment;

(2) Electrocatalytic oxidation treatment: electrocatalytic oxidation treatment is performed on the wastewater after coagulation treatment;

(3) Solid-liquid separation treatment: The wastewater after electrocatalytic oxidation treatment is allowed to stand and then separated.

According to the specific embodiment of the present invention, preferably, in step (1), the coagulation treatment includes the following steps: adding flocculant to the waste water tank, mixing, and filtering through a plate and frame filter press.

According to a specific embodiment of the present invention, preferably, in step (1), the flocculant used in the coagulation treatment includes polyaluminum iron silicate PSAF and polyaluminum chloride PAC.

According to a specific embodiment of the present invention, preferably, in step (1), the mass ratio of the polyferric aluminum silicate and polyaluminum chloride is 10-40:1.

According to the specific embodiment of the present invention, preferably, in step (1), the coagulation treatment time is 1-2 h.

According to the specific embodiment of the present invention, preferably, in step (1), the amount of flocculant added in the coagulation treatment is 1-3kg/m ³ .

According to the specific embodiment of the present invention, preferably, in step (2), the current density of the electrocatalytic oxidation treatment is 10-20mA/cm ² , the voltage is 7-10V, and the electrocatalytic oxidation treatment time is 10-50 minutes.

According to a specific embodiment of the present invention, preferably, in step (2), the pH during the electrocatalytic oxidation treatment is 6-8.

According to a specific embodiment of the present invention, preferably, in step (2), the electrocatalytic anode plate in the electrocatalytic oxidation treatment is selected from lead dioxide plates or tin antimony plates, and the electrocatalytic cathode plate is selected from Stainless steel plate.

According to a specific embodiment of the present invention, preferably, in step (2), the distance between the anode and cathode plates in the electrocatalytic oxidation treatment is 0.5-3cm.

According to the specific embodiment of the present invention, preferably, the number of electrode plates is 67×2 pieces.

According to the specific embodiment of the present invention, preferably, in step (3), the wastewater treated by electrocatalytic oxidation is left to stand and then reinjected after meeting the standards. The reinjection standard is SY/T 5329-2022.

According to the specific embodiment of the present invention, preferably, the standing time is 10-60 minutes.

According to a specific embodiment of the present invention, preferably, the oilfield drilling wastewater treated by the electrocatalytic treatment method for oilfield drilling wastewater meets the reinjection disposal requirements SY/T 5329-2022.

According to the specific embodiment of the present invention, the above-mentioned treatment method includes the following specific steps, as shown in Figure 1:

(1) Pretreatment of oilfield drilling wastewater by coagulation and plate and frame filter press;

(2) Treat the pretreated drilling wastewater in the electrocatalytic reaction device tank, and energize it for a certain period of time under the action of a constant current;

(3) Leave to settle for a few minutes or simply filter and drain the supernatant to meet the requirements for efficient reinjection.

The present invention also provides an oilfield drilling wastewater electrocatalytic treatment system used in the above oilfield drilling wastewater electrocatalytic treatment method, which includes a coagulation treatment module, an electrocatalytic oxidation module, and a solid-liquid separation module; the coagulation treatment module is provided with a wastewater The electrocatalytic oxidation module is equipped with an electrocatalytic reaction device; the solid-liquid separation module is equipped with a sedimentation tank.

The treatment method of the present invention can achieve the gel breaking and destabilizing effect of drilling wastewater in a short time. The treatment method can achieve the gel breaking and destabilizing effect of drilling wastewater in a short time, and effectively remove the suspended solids SS and SS in the waste water. Oils reduce the median particle size of particles; the pH change range is small. In addition, the present invention also has good removal effects on COD and ammonia nitrogen. By adjusting the process parameters and the number of plates, the quality of the effluent can be further improved; and the treatment energy consumption can be effectively controlled; it is a method to achieve efficient reinjection of drilling wastewater.

The invention has the following beneficial effects:

1. The treatment method of the present invention has a small floc production, accounting for 5-10% of the treated water, and the subsequent treatment energy consumption is low.

2. The treatment method of the present invention is simple. The wastewater after coagulation treatment is treated by electrocatalytic oxidation, and finally through natural sedimentation or simple filtration, the effluent can meet the reinjection standard.

3. In the present invention, the optimal process parameters can be obtained by adjusting the residence time, current density, and electrode plate spacing.

4. The present invention has low energy consumption, with power consumption at 4.5-5 degrees/m ³ , which greatly reduces the construction cost of environmental protection and the operating cost of sewage treatment. It has broad application prospects and is suitable for promotion and application.

5. The organic matter mineralization efficiency of the present invention is high, the electrode plates are not easy to scale and are easy to clean, the electrocatalytic electrode plates are stable in effect, do not need to be replaced frequently, and the labor maintenance cost is low.

6. The present invention can fully solve the problem of poor treatment effect on heavy metals and fine suspended particles in the process of drilling wastewater treatment by plate and frame filter press.

7. The present invention treats drilling wastewater through pressure filtration combined with electrocatalytic oxidation. As a new treatment method for drilling wastewater, it makes full use of the advantages of different treatment technologies and integrates the advantages of physical and chemical separation and advanced oxidation technology to effectively deal with drilling. The complexity of wastewater improves treatment efficiency, reduces pollutant emissions, reduces treatment costs, and reduces the impact on the environment; it shows unique advantages in the field of drilling wastewater reinjection and represents an emerging treatment technology. It has potential application prospects for further processing difficult-to-degrade fracturing flowback fluid.

Description of the drawings

Figure 1 is a flow chart of the processing method;

Figure 2 is a structural diagram of an electrocatalytic small-scale treatment device, in which 1-DC power supply, 2-electrocatalytic reactor, 3-cathode electrode plate, 4-connected water inlet pipe, 5-anode electrode plate, 6 water outlet pipe;

Figure 3 is a graph of changes in SS and pH over time;

Figure 4 is a graph showing changes in COD and ammonia nitrogen over time;

Figure 5 is a structural diagram of the flocculation filter press module device, where 1-waste tank, 2-water inlet pump, 3-water inlet valve, 4-thrust plate, 5-filter plate and filter cloth, 6-load-bearing wall, 7- Cross beam, 8-pressure plate, 9-hydraulic station;

Figure 6 is a structural diagram of the electrocatalytic pilot treatment device, where 1-control panel, 2-distribution box, 3-wires, 4-water inlet pipe, 5-anode plate, 6-cathode plate, 7-outlet pipe , 8-reaction tank;

Figure 7 is a structural diagram of the sedimentation tank device of the solid-liquid separation module, where 1-water inlet, 2-water inlet area, 3-sludge area, 4-sedimentation area, 5-water outlet area, 6-water outlet;

Figure 8 is a graph showing changes in SS and pH over time;

Figure 9 is a graph showing changes in COD and ammonia nitrogen over time.

Detailed ways

In order to have a clearer understanding of the technical features, purposes and beneficial effects of the present invention, the technical solutions of the present invention are described in detail below, but this should not be understood as limiting the implementable scope of the present invention.

Example 1

This embodiment provides an electrocatalytic small-scale treatment method for oilfield drilling wastewater, which includes the following steps:

Drilling wastewater is concentrated in the wastewater pool and added with PSAF and PAC for gel breaking and flocculation. The flocculant dosage is 3kg/m ³ , the feed ratio of PSAF and PAC is 15:1, and the flocculation time is 2h. The treated waste liquid is transported to the plate and frame. The filter press performs filtration treatment (the device structure is shown in Figure 5), and the waste residue after the filtration is solidified. The filtrate is taken into a beaker and pumped into the electrocatalytic reactor by a peristaltic pump, as shown in Figure 2. The anode plate of the catalytic reactor uses Ti/PbO ₂ plates, the number is 4 pieces, the cathode plate uses stainless steel plates, the number is 5 pieces, the distance between the plates is 5mm, the DC power supply is used in parallel, and the plates are arranged from left to right . During the continuous flow reaction process, three groups of reactors 1, 2, and 3 are set up with the same water input, the current density is set to 25mA/cm ² , 20mA/cm ² , and 5mA/cm ² respectively, the cell voltage is 4.5-5.5V, and the residence time is 30 minutes.

Reactor 1: Pressure filter inlet water: pH7.7; COD 2500mg/L; ammonia nitrogen 41mg/L; oil 21.2mg/L; SS2000mg/L; electrocatalytic effluent: pH6.5; COD 380mg/L; ammonia nitrogen 2.1mg //L; oil 0.8mg/L; SS 65mg/L, let the water stand for 30 minutes, SS drops to 30mg/L, and SS index cannot meet the reinjection standard;

Reactor 2: Pressure filter inlet water: pH7.7; COD 2500mg/L; ammonia nitrogen 41mg/L; oil 21.2mg/L; SS2000mg/L; electrocatalytic effluent: pH7.3; COD 303mg/L; ammonia nitrogen 1.7mg /L; oil 0.36mg/L; SS 29.7mg/L. When the outlet water is left standing for 30 minutes, SS drops to 8.740mg/L (reaching the reinjection standard SY/T 5329-2022). During the treatment process, SS and pH change with time. The changes are shown in Figure 3, and the changes in COD and ammonia nitrogen content over time are shown in Figure 4.

Reactor 3: Pressure filter inlet water: pH7.7; COD 2500mg/L; ammonia nitrogen 41mg/L; oil 21.2mg/L; SS2000mg/L; electrocatalytic effluent: pH8.0; COD 450mg/L; ammonia nitrogen 3.5mg //L; oil 2.5mg/L; SS 118mg/L. If the water is left to stand for 30 minutes, the SS drops to 78mg/L, and the SS index cannot meet the reinjection standard.

Example 2

This embodiment provides an electrocatalytic pilot treatment method for oilfield drilling wastewater, which includes the following steps:

Drilling wastewater is concentrated in the wastewater pool and added with PSAF and PAC for gel breaking and flocculation. The flocculant dosage is 2kg/m ³ , the PSAF and PAC feed ratio is 15:1, and the flocculation time is 2h. The treated waste liquid is transported to the plate and frame press. The filter performs filter press processing (the device structure is shown in Figure 5), the waste residue after the filter press is solidified, and the filtrate is directly pumped into the electrocatalytic pilot treatment device, as shown in Figure 6, the anode plate (lead dioxide electrode ) quantity is 33 pieces, the number of cathode plates (stainless steel) is 34 pieces, the distance between cathode and anode plates is 2cm, a DC power supply is used in parallel, and the plates are arranged from left to right. During the continuous flow reaction, the current density was set to 20mA/cm ² , the voltage was between 7-10V, and the residence time was 50min.

Press filter inlet water: pH 6.5; COD 2000mg/L; ammonia nitrogen 35mg/L; oil 20.2mg/L; SS 1800mg/L; electrocatalytic effluent: pH 5.9; COD 180mg/L; ammonia nitrogen 1.2mg/L; oil 3.6 mg/L; SS 65mg/L. The effluent is discharged into the sedimentation tank (the structure is shown in Figure 7) and naturally settles for 60 minutes, and the SS drops to 7.866mg/L; the median particle size reaches 1.257μm, fully meeting the standards for reinjection and utilization of drilling wastewater (SY/T 5329-2022) .

During the treatment process, the changes of SS and PH with time are shown in Figure 8, and the changes of COD and ammonia nitrogen content with time are shown in Figure 9. After the drilling wastewater undergoes electrocatalytic oxidation reaction, the concentration of metal ions in the electrocatalytic inlet and outlet water is shown in Table 1. , the XRF elemental analysis of the suspended solids generated by the electrocatalytic oxidation reaction of drilling wastewater is shown in Table 2.

Table 1 Metal ion concentration in the inlet and outlet water of the electrocatalytic system

Metal ion Inlet water concentration mg/L Effluent concentration mg/L Fe 0.81 0.03 Al 0.142 0.774 Ca 0.03 0 Pb 0 0

As can be seen from Table 1, metal ions in drilling wastewater are effectively removed, with the removal rate of iron ions as high as 96%; the concentration of hardness ions such as calcium ions is reduced to below the detection limit, and the concentration of lead ions is also below the detection limit; explanation The lead element of the catalytic electrode appears in the form of precipitation. Although the concentration of aluminum ions increased slightly, it was still at a low level. This slight increase may be due to the aluminum-containing flocs being dissolved in water after mineralization by hydroxyl radicals. Small changes in aluminum ion concentration will not have any negative impact on the drilling wastewater reinjection process.

Table 2 Elemental analysis of suspended matter generated by electrocatalysis

The results show that there are many metal elements in the suspended solids, and the metal element with the highest content is Al, accounting for 17.26% of the total element, which is mainly introduced by the addition of flocculants PSAF and PAC.

Claims (10)

1. An electrocatalytic treatment method for oilfield drilling wastewater, which includes the following steps: (1) Coagulation treatment; (2) Electrocatalytic oxidation treatment: electrocatalytic oxidation treatment is performed on the wastewater after coagulation treatment; (3) Solid-liquid separation treatment: The wastewater after electrocatalytic oxidation treatment is allowed to stand and then separated. 2. The electrocatalytic treatment method of oilfield drilling wastewater according to claim 1, wherein in step (1), the flocculant used in the coagulation treatment includes polyferric aluminum silicate and polyaluminum chloride; Preferably, the mass ratio of the polyaluminum iron silicate and polyaluminum chloride is 10-40:1. 3. The electrocatalytic treatment method of oilfield drilling wastewater according to claim 1, wherein in step (1), the coagulation treatment time is 1-2 hours. 4. The electrocatalytic treatment method of oilfield drilling wastewater according to claim 1, wherein in step (1), the amount of flocculant added in the coagulation treatment is 1-3kg/m ³ . 5. The method for electrocatalytic treatment of oilfield drilling wastewater according to claim 1, wherein in step (2), the current density of the electrocatalytic oxidation treatment is 10-20mA/cm ² and the voltage is 7-10V. Oxidation treatment time is 10-50min; Preferably, the pH during the electrocatalytic oxidation treatment is 6-8. 6. The method for electrocatalytic treatment of oilfield drilling wastewater according to claim 1, wherein in step (2), the electrocatalytic anode plate in the electrocatalytic oxidation treatment is selected from a lead dioxide plate or a tin-antimony plate. , the electrocatalytic cathode plate is selected from stainless steel plates. 7. The electrocatalytic treatment method of oilfield drilling wastewater according to claim 1, wherein in step (2), the distance between the anode and cathode plates in the electrocatalytic oxidation treatment is 0.5-3cm; Preferably, the number of electrode plates is 67×2 pieces. 8. The electrocatalytic treatment method of oilfield drilling wastewater according to claim 1, wherein in step (3), the wastewater after electrocatalytic oxidation treatment is allowed to stand and then reinjected after reaching the standard; Preferably, the resting time is 10-60 minutes. 9. The oilfield drilling wastewater electrocatalytic treatment method according to claim 1, wherein the oilfield drilling wastewater treated by the oilfield drilling wastewater electrocatalytic treatment method meets the reinjection disposal requirements SY/T 5329-2022. 10. The oilfield drilling wastewater electrocatalytic treatment system used in the oilfield drilling wastewater electrocatalytic treatment method according to any one of claims 1 to 9, which includes a coagulation treatment module, an electrocatalytic oxidation module, and a solid-liquid separation module; The coagulation treatment module is equipped with a waste pool and a plate and frame filter press device; The electrocatalytic oxidation module is provided with an electrocatalytic reaction device; The solid-liquid separation module is provided with a sedimentation tank.