A system for disposal of drilling and reservoir modification waste fluids

Abstract

The application discloses a kind of drilling and reservoir reconstruction waste liquid processing system, it is related to waste liquid processing technical field, the oil removal system is carried out oil removal treatment to waste liquid;The micro-electrolysis oxidation system is carried out PH value adjustment and electrolytic oxidation to waste liquid after oil removal treatment;The pH adjustment system is carried out secondary PH value adjustment treatment to waste liquid after electrolytic oxidation;The ion removal system is carried out ion removal treatment to waste liquid after secondary PH value adjustment treatment;The coagulation and inclined plate sedimentation system is carried out coagulation and flocculation treatment to waste liquid after ion removal treatment and settles, carries out solid-liquid separation;Waste liquid after solid-liquid separation is carried out multistage filtration by the multistage filtration system and water quality neutralization system and then carries out third PH value adjustment treatment, so that it reaches discharge standard.The application improves waste liquid processing effect by multiple systems and reduces processing cost.

Description

Technical Field

[0001] This invention relates to the field of waste liquid treatment technology, and more specifically to a drilling and reservoir stimulation waste liquid treatment system. Background Technology

[0002] Globally, oil and gas exploration and production activities generate a large amount of drilling and reservoir stimulation waste fluids each year. If these waste fluids are not properly treated, they will directly threaten surface water and groundwater resources, thereby causing serious impacts on the ecological environment and human health.

[0003] Drilling and reservoir stimulation wastewater contains various harmful substances, including but not limited to heavy metals, organic matter, suspended solids, and hazardous chemicals. The diverse types of pollutants and variable water quality in this wastewater make its treatment complex. Although various technologies have been applied to wastewater treatment, such as physical, chemical, and biological methods, physical methods, while capable of separating oil and water, cannot effectively reduce viscosity or total hardness. Chemical methods have advantages in reducing viscosity and COD levels, but they are prone to secondary pollution, and some chemical treatment methods may only be effective against specific types of pollutants, limiting their application. Biological methods are effective in treating wastewater, but their operating conditions are demanding, making on-site application difficult.

[0004] Therefore, how to improve the treatment effect of waste liquid and reduce the treatment cost is a problem that needs to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention provides a drilling and reservoir stimulation wastewater treatment system, which consists of an oil removal system, a micro-electrolysis oxidation system, a pH adjustment system, an ion removal system, a coagulation and inclined plate sedimentation system, a multi-stage filtration system, and a water neutralization system. Simultaneously, an advanced algorithm is designed to predict the effluent viscosity of the wastewater based on different process parameters. By evaluating the impact of different process parameters on wastewater treatment, the system enhances process flexibility, improves treatment efficiency, reduces the amount of reagents used in the micro-electrolysis oxidation system, and thus lowers treatment costs.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A drilling and reservoir stimulation wastewater treatment system includes: an oil removal system, a micro-electrolysis oxidation system, a pH adjustment system, an ion removal system, a coagulation and inclined plate sedimentation system, a multi-stage filtration system, and a water neutralization system connected in sequence. The oil removal system removes oil from the wastewater. The micro-electrolysis oxidation system adjusts the pH of the oil-removed wastewater and performs electrolytic oxidation. The pH adjustment system performs secondary pH adjustment on the electrolytically oxidized wastewater. The ion removal system removes ions from the wastewater after the secondary pH adjustment. The coagulation and inclined plate sedimentation system performs coagulation and flocculation treatment and sedimentation on the ion-removed wastewater to achieve solid-liquid separation. The solid-liquid separated wastewater undergoes multi-stage filtration through the multi-stage filtration system and the water neutralization system, followed by a third pH adjustment treatment to meet discharge standards.

[0008] Preferably, the oil removal system consists of a coalescing oil separator, and the oil content in the waste liquid after treatment by the coalescing oil separator is 0-50 mg / L.

[0009] Preferably, in the micro-electrolysis oxidation system, the waste liquid after oil removal treatment enters the system from the bottom via overflow. The pH is adjusted by adding a pH adjuster, and electrolysis oxidation occurs through the micro-electrolysis material, while aeration promotes the oxidation reaction. The micro-electrolysis reaction time is 40–100 min; the pH of the waste liquid is adjusted to 3–4; the porosity of the micro-electrolysis material is 60–80%; 40–160 kg of micro-electrolysis material is added per cubic meter of waste liquid; the aeration rate to waste liquid ratio is 6:1–12:1; and the waste liquid viscosity is 1–8 mPa·s.

[0010] Preferably, the pH adjustment system is equipped with an alkaline solvent of 300-1000 mg / L to maintain the pH of the waste liquid at 8-9; the pH adjustment system is equipped with an aeration device, which is kept running while sodium hydroxide is added; the ratio of aeration volume to waste liquid is 6:1 to 12:1; and the aeration time is within 20-40 minutes.

[0011] Preferably, in the ion removal system, the waste liquid enters the ion removal system from the bottom via overflow, and the dosage of the ion removal agent is 1000–3500 mg / L; the ion removal agent is a composite agent composed of agent A, agent B, and auxiliary agents, including agent A (1–10% sodium sulfate, 1–5% aluminum sulfate, 1–5% potassium carbonate); agent B (20–50% sodium carbonate); and auxiliary agent (20–30% bentonite); the ion removal system is equipped with a stirring paddle, and the stirring motor rotates at 100–400 r / min; the residence time of the waste liquid in the ion removal system is 20–40 min.

[0012] Preferably, the coagulation and inclined plate sedimentation system includes a coagulation tank and an inclined plate sedimentation tank. The waste liquid, after ion removal treatment, overflows into the coagulation tank from the bottom. The coagulation tank is divided into two chambers, A and B. The waste liquid overflows into chamber A from the bottom. Chamber A is supplemented with 300–1000 mg / L of PAC and is equipped with a stirring paddle with a motor speed of 300–600 r / min. The residence time of the waste liquid in chamber A is 10–20 min. The waste liquid overflows into chamber B from the bottom. Chamber B is supplemented with 10–40 mg / L of PAM and is equipped with a stirring paddle with a motor speed of 100–240 r / min. The residence time of the waste liquid in chamber B is 10–20 min. The coagulated waste liquid overflows into the inclined plate sedimentation tank for sludge settling, with a residence time of 60–150 min.

[0013] Preferably, in the multi-stage filtration system, the waste liquid overflowing from the coagulation and inclined plate sedimentation system is pressurized by a pump and then enters the multi-stage filtration system. The multi-stage filtration system consists of anthracite, glass fiber, and polyester fiber from top to bottom. The residence time of the waste liquid in the multi-stage filtration system is 30 to 60 minutes.

[0014] Preferably, in the water neutralization system, the waste liquid after being treated by the multi-stage filtration system enters the water neutralization system by overflow. The water neutralization system is equipped with a stirring paddle, and the stirring motor rotates at a speed of 100-400 r / min. The pH adjuster is citric acid, and its dosage is 1000-2300 mg / L. The treated waste liquid exits the system by overflow or by pump pressurization.

[0015] Preferably, the micro-electrolysis oxidation system predicts the effluent viscosity of the waste liquid using a preset algorithm. Specifically, this includes establishing a training set using pH, micro-electrolysis material dosage, reaction time, aeration rate, and waste liquid viscosity as training samples; wherein pH, micro-electrolysis material dosage, reaction time, and aeration rate are inputs, and waste liquid viscosity is the output; and the usage of the input parameters of the micro-electrolysis oxidation system is adjusted based on the predicted effluent viscosity.

[0016] As can be seen from the above technical solution, compared with the prior art, the present invention discloses a drilling and reservoir stimulation wastewater treatment system. By optimizing the key reaction parameters of iron-carbon micro-electrolysis, including the dosage of micro-electrolysis materials, the pH of the reaction, the aeration rate, and the reaction duration, it ensures efficient treatment of drilling and reservoir stimulation wastewater while also optimizing the utilization efficiency of raw materials and avoiding problems such as effluent discoloration. The present invention is characterized by its economy and high efficiency, achieving dual optimization of cost-effectiveness and treatment efficiency. By adding ion control agents, the total hardness and high-valence ion content of the wastewater are effectively reduced. The treated wastewater can be reinjected or reused, reducing wastewater pollution to the environment, improving wastewater treatment efficiency, and reducing the difficulty of subsequent treatment. Through the accompanying advanced algorithm, the wastewater treatment effect can be predicted according to different process parameters. By predicting the impact of different process parameters on the wastewater treatment effect, the flexibility of the process is improved, the treatment efficiency is increased, the amount of reagents used is reduced, and thus the treatment cost is saved. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure provided by the present invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] This invention discloses a drilling and reservoir stimulation waste fluid treatment system, such as... Figure 1As shown, the system includes: an oil removal system, a micro-electrolysis oxidation system, a pH adjustment system, an ion removal system, a coagulation and inclined plate sedimentation system, a multi-stage filtration system, and a water neutralization system connected in sequence. The oil removal system removes oil from the waste liquid; the micro-electrolysis oxidation system adjusts the pH of the waste liquid after oil removal and performs electrolysis oxidation; the pH adjustment system performs secondary pH adjustment on the waste liquid after electrolysis oxidation; the ion removal system removes ions from the waste liquid after secondary pH adjustment; the coagulation and inclined plate sedimentation system performs coagulation and flocculation treatment and sedimentation on the waste liquid after ion removal, achieving solid-liquid separation; the solid-liquid separated waste liquid undergoes multi-stage filtration through the multi-stage filtration system and the water neutralization system, and then undergoes tertiary pH adjustment to meet discharge standards.

[0021] The system comprises the following components: Oil Removal System: First, wastewater enters the oil removal system, where oil is removed by a coalescing oil separator. Micro-electrolysis Oxidation System: Next, the wastewater enters the micro-electrolysis oxidation system, where it is treated using micro-electrolysis materials and pH adjustment. pH Adjustment System: Then, the wastewater enters the pH adjustment system, where the pH value is adjusted by adding alkali. Ion Removal System: The next step is the ion removal system, which removes ions from the wastewater by adding an ion controller. Coagulation Tank: The wastewater then enters the coagulation tank, where it is further treated by adding coagulants and flocculants. Inclined Plate Settling Tank: After coagulation and flocculation treatment, the wastewater enters the inclined plate settling tank. Larger flocs slide down the inclined plate surface to the bottom under gravity, achieving solid-liquid separation. The purified water is then discharged from the top. Multi-Stage Filtration System: The wastewater then enters the multi-stage filtration system, where it is further purified by multiple filters. Water neutralization system: Wastewater enters the water neutralization system, where pH adjusters are added to neutralize the pH value of the wastewater so that it meets discharge standards.

[0022] In one specific embodiment, the oil removal system consists of a coalescing oil separator, and the oil content in the waste liquid after treatment by the coalescing oil separator is 0-50 mg / L.

[0023] In one specific embodiment, in the micro-electrolysis oxidation system, the waste liquid after oil removal treatment enters the system from the bottom via overflow. The pH value is adjusted by adding a pH adjuster, and electrolysis oxidation is carried out through the micro-electrolysis material, while aeration is performed to promote the oxidation reaction. The micro-electrolysis reaction time is 40-100 min; the pH of the waste liquid is adjusted to 3-4; the porosity of the micro-electrolysis material is 60-80%; 40-160 kg of micro-electrolysis material is added per cubic meter of waste liquid; the aeration rate to waste liquid ratio is 6:1-12:1; and the viscosity of the waste liquid is 1-8 mPa·s.

[0024] In one specific embodiment, an alkaline solvent of 300–1000 mg / L is added to the pH adjustment system to maintain the pH of the waste liquid at 8–9; the pH adjustment system is equipped with an aeration device, which is kept running while sodium hydroxide is added; the ratio of aeration volume to waste liquid is 6:1–12:1; and the aeration time is within 20–40 minutes.

[0025] In one specific embodiment, the pH of the wastewater will rise to a certain extent after passing through the micro-electrolysis oxidation system. The pH is maintained at 8-9 by adding 300-1000 mg / L of sodium hydroxide. During the pH adjustment process, aeration promotes the growth of Fe... 2+ The oxidation effectively avoids the problem of effluent color reversal, improves pH adjustment efficiency, and continuous aeration can prevent the iron filings from accumulating and hardening due to the deposition of pollutants on the surface, thus maintaining the activity and reaction efficiency of the iron filings.

[0026] In one specific embodiment, in the ion removal system, the waste liquid enters the system from the bottom via overflow, and the dosage of the ion removal agent is 1000–3500 mg / L. The ion removal agent is a composite agent composed of agent A, agent B, and auxiliary agents, including agent A (1–10% sodium sulfate, 1–5% aluminum sulfate, 1–5% potassium carbonate), agent B (20–50% sodium carbonate), and auxiliary agent (20–30% bentonite). The ion removal system is equipped with a stirring paddle, and the stirring motor rotates at 100–400 r / min. The residence time of the waste liquid in the ion removal system is 20–40 min. The total hardness (calculated as calcium carbonate) of the wastewater after treatment by the ion removal system is less than 300 mg / L.

[0027] In one specific embodiment, the coagulation and inclined plate settling system includes a coagulation tank and an inclined plate settling tank. Wastewater treated by ion removal overflows into the coagulation tank from the bottom. The coagulation tank is divided into two chambers, A and B. Wastewater overflows into chamber A from the bottom. Chamber A is supplemented with 300–1000 mg / L of PAC and is equipped with a stirring paddle with a motor speed of 300–600 r / min. The residence time of the wastewater in chamber A is 10–20 min. Wastewater overflows into chamber B from the bottom. Chamber B is supplemented with 10–40 mg / L of PAM and is equipped with a stirring paddle with a motor speed of 100–240 r / min. The residence time of the wastewater in chamber B is 10–20 min. The coagulated wastewater overflows into the inclined plate settling tank for sludge settling, with a residence time of 60–150 min.

[0028] In one specific embodiment, in the multi-stage filtration system, the waste liquid overflowing from the coagulation and inclined plate sedimentation system is pressurized by a pump and then enters the multi-stage filtration system. The multi-stage filtration system consists of anthracite, glass fiber, and polyester fiber from top to bottom. The residence time of the waste liquid in the multi-stage filtration system is 30 to 60 minutes.

[0029] In one specific embodiment, in the water neutralization system, the waste liquid treated by the multi-stage filtration system enters the water neutralization system by overflow. The water neutralization system is equipped with an agitator, and the speed of the agitator motor is 100-400 r / min. The pH adjuster is citric acid, and its dosage is 1000-2300 mg / L. The treated waste liquid exits the system by overflow or pump pressurization. The treated wastewater can be reinjected or used to prepare drilling and fracturing fluids.

[0030] In one specific embodiment, the micro-electrolysis oxidation system predicts the effluent viscosity of the waste liquid using a preset algorithm. Specifically, this includes establishing a training set using pH, micro-electrolysis material dosage, reaction time, aeration rate, and waste liquid viscosity as training samples. Here, pH, micro-electrolysis material dosage, reaction time, and aeration rate are inputs, and waste liquid viscosity is the output. The usage of the input parameters of the micro-electrolysis oxidation system is adjusted based on the predicted effluent viscosity.

[0031] The preset algorithm can predict the effluent viscosity of wastewater based on different process parameters. By predicting the impact of different process parameters on the wastewater treatment effect, it can improve the flexibility of the process, increase treatment efficiency, reduce the amount of reagents used, and thus save treatment costs.

[0032] This algorithm transforms a low-dimensional nonlinear problem into a high-dimensional linear problem using a kernel function. By seeking the optimal regression hyperplane, the problem is transformed into a quadratic convex programming problem. Finally, the algorithm solves the low-dimensional nonlinear problem by finding the global optimal solution to the quadratic convex programming problem.

[0033] Furthermore, suppose the given training samples are a set T = {(x1,y1),(x2,y2),…,(x...} of m samples in an n+1 dimensional space. i ,y i ),…,(x m ,y m )},x i ∈R n It is the input vector, y i ∈R is the output value.

[0034] Furthermore, this algorithm is used to find a suitable regression function f(x).

[0035] Furthermore, the established regression function formula is as follows:

[0036] f(x)= ωg(x)+ b (1)

[0037] Furthermore, x is the input vector; g() is the mapping function; ω is the weight vector; and b is the threshold.

[0038] Furthermore, the regression prediction problem is transformed into an optimization problem of solving a quadratic programming problem, as shown in the formula:

[0039]

[0040] Furthermore, in the formula: ε is the insensitivity function; c is the penalty factor; ξ i and ξ i * These are slack variables.

[0041] Furthermore, by using kernel functions to map the above optimization problem to a higher-dimensional space, we obtain the dual problem of this problem, as shown in the formula:

[0042]

[0043] Furthermore, L is the objective function, α i β i Let α be the Lagrange multiplier for the i-th training sample. j β j K(x) is the Lagrange multiplier for the j-th training sample; i x j ) is the kernel function.

[0044] Furthermore, K() generally adopts a radial basis kernel function, the basic form of which is shown in equation (4):

[0045]

[0046] Furthermore, γ is the regularization parameter.

[0047] Furthermore, by solving this dual problem, the final regression function can be obtained, which is:

[0048]

[0049] Furthermore, n m It is the number of vectors, α i and b* represents the Lagrange multiplier; b* represents the threshold.

[0050] Based on the above algorithm, the viscosity of the effluent wastewater from this process can be predicted.

[0051] In Specific Embodiment 1, the drilling and reservoir stimulation waste fluid in this embodiment is taken from a certain joint station.

[0052] Step 1: After being pressurized by a pump, the wastewater enters the coalescing oil separator from the bottom. After being treated by the coalescing oil separator, the oil content in the wastewater is 9 mg / L.

[0053] Step 2: After passing through the oil removal system, the wastewater overflows from the coalescing oil remover and enters the micro-electrolysis oxidation system from the bottom. The micro-electrolysis reaction time is 60 minutes.

[0054] Furthermore, after treatment with a pH adjuster, the pH of the wastewater in the micro-electrolysis oxidation system is ensured to be 4; the porosity of the micro-electrolysis material is 66%; 120 kg of micro-electrolysis material is added to each cubic meter of wastewater; the aeration rate to wastewater ratio is (10:1); and the viscosity of the wastewater is 1.83 mPa·s.

[0055] Step 3: After passing through the micro-electrolysis oxidation system, the pH of the wastewater will rise to a certain extent. The pH of the wastewater will be maintained at around 8 by adding 600 mg / L of sodium hydroxide.

[0056] Furthermore, the pH adjustment system is equipped with an aeration device, which is kept running while sodium hydroxide is added; the aeration rate to wastewater ratio is 10:1; and the aeration time is 20 minutes.

[0057] Step four: After being treated by the pH adjustment system, the wastewater overflows from the bottom into the ion removal system, where an ion removal agent is added.

[0058] Furthermore, the dosage of the ion removal agent is 1342 mg / L; the ion removal agent is a compound agent, composed of agent A, agent B, and auxiliary agents, and consists of the following components by mass percentage:

[0059] Agent A: 10% sodium sulfate, 5% aluminum sulfate, 5% potassium carbonate; Agent B: 50% sodium carbonate; Additive: 30% bentonite; The ion removal system is equipped with a stirring paddle, and the stirring motor speed is 300 r / min; The total hardness (calculated as calcium carbonate) of the wastewater after treatment by the ion removal system is 180 mg / L; The residence time of the wastewater in the ion removal system is 20 min.

[0060] Step 5: After ion treatment, the wastewater overflows from the bottom into the coagulation tank.

[0061] Furthermore, the coagulation tank can be divided into two chambers, A and B. Wastewater overflows into chamber A from the bottom, where 1000 mg / L of PAC is added. Chamber A is equipped with a stirring paddle, and the stirring motor speed is 500 r / min. The residence time of wastewater in chamber A is 10 min. Wastewater overflows into chamber B from the bottom, where 10 mg / L of PAM is added. Chamber B is equipped with a stirring paddle, and the stirring motor speed is 100 r / min. The residence time of wastewater in chamber B is 15 min. The coagulated wastewater overflows into the inclined plate settling tank. The residence time of wastewater in the inclined plate settling tank is 90 min. The sludge at the bottom of the inclined plate settling tank is periodically transported for volume reduction treatment.

[0062] Step 6: The wastewater overflowing from the coagulation and inclined plate settling system is pressurized by a pump and then enters the multi-stage filtration system.

[0063] Furthermore, the multi-stage filtration system consists of three filter media: anthracite, glass fiber, and polyester fiber; the wastewater residence time in the multi-stage filtration system is 40 minutes.

[0064] Step 7, Water neutralization system: Wastewater treated by the multi-stage filtration system overflows into the water neutralization system.

[0065] Furthermore, the water neutralization system is equipped with an agitator, and the agitator motor rotates at 200 r / min; the pH adjuster is citric acid, and the dosage is 1600 mg / L; the treated wastewater is discharged from the system by overflow or pump pressurization, and the treated wastewater can be reinjected or used to prepare drilling and fracturing fluids.

[0066] Example 2

[0067] In this embodiment, the drilling and reservoir stimulation wastewater is taken from a joint station. Unlike Embodiment 1, in Embodiment 2, the wastewater is taken from different well sites and different systems. This embodiment provides a drilling and reservoir stimulation wastewater treatment system, including an oil removal system, a micro-electrolysis oxidation system, a pH adjustment system, an ion removal system, a coagulation and inclined plate sedimentation system, a multi-stage filtration system, and a water neutralization system.

[0068] Step 1: After being pressurized by a pump, the wastewater enters the coalescing oil separator from the bottom. After being treated by the coalescing oil separator, the oil content in the wastewater is 13 mg / L.

[0069] Step 2: After passing through the oil removal system, the wastewater overflows from the coalescing oil remover and enters the micro-electrolysis oxidation system from the bottom. The micro-electrolysis reaction time is 60 minutes.

[0070] Furthermore, after treatment with a pH adjuster, the pH of the wastewater in the micro-electrolysis oxidation system is ensured to be 4; the porosity of the micro-electrolysis material is 66%; 120 kg of micro-electrolysis material is added to each cubic meter of wastewater; the aeration rate to wastewater ratio is (10:1); and the viscosity of the wastewater is 2.67 mPa·s.

[0071] Step 3: After passing through the micro-electrolysis oxidation system, the pH of the wastewater will rise to a certain extent. The pH of the wastewater will be maintained at around 8 by adding 600 mg / L of sodium hydroxide.

[0072] Furthermore, the pH adjustment system is equipped with an aeration device, which is kept running while sodium hydroxide is added; the aeration rate to wastewater ratio is 10:1; and the aeration time is 20 minutes.

[0073] Step four: After being treated by the pH adjustment system, the wastewater overflows from the bottom into the ion removal system, where an ion removal agent is added.

[0074] Furthermore, the dosage of the ion removal agent is 3436 mg / L; the ion removal agent is a compound agent, composed of agent A, agent B, and auxiliary agents, and consists of the following components by mass percentage:

[0075] Agent A: Sodium sulfate 10%, aluminum sulfate 5%, potassium carbonate 5%;

[0076] Agent B: Sodium carbonate 50%;

[0077] Additives: 30% bentonite.

[0078] Furthermore, the ion removal system is equipped with a stirring paddle, and the stirring motor rotates at 300 r / min; the total hardness (calculated as calcium carbonate) of the wastewater after treatment by the ion removal system is 300 mg / L; the residence time of the wastewater in the ion removal system is 20 min.

[0079] Step 5: After ion treatment, the wastewater overflows from the bottom into the coagulation tank.

[0080] Furthermore, the coagulation tank can be divided into two chambers, A and B. Wastewater overflows into chamber A from the bottom. Chamber A contains 700 mg / L of PAC.

[0081] Furthermore, chamber A is equipped with a stirring paddle, and the stirring motor speed is 500 r / min; the wastewater residence time in chamber A is 10 min; the wastewater overflows into chamber B from the bottom, where 20 mg / L of PAM is added; chamber B is equipped with a stirring paddle, and the stirring motor speed is 100 r / min; the wastewater residence time in chamber B is 15 min; the coagulated wastewater overflows into the inclined plate sedimentation tank; the wastewater residence time in the inclined plate sedimentation tank is 90 min; the sludge at the bottom of the inclined plate sedimentation tank is periodically transported for volume reduction treatment.

[0082] Step 6: The wastewater overflowing from the coagulation and inclined plate settling system is pressurized by a pump and then enters the multi-stage filtration system.

[0083] Furthermore, the multi-stage filtration system consists of three filter media: anthracite, glass fiber, and polyester fiber; the wastewater residence time in the multi-stage filtration system is 40 minutes.

[0084] Step 7, Water neutralization system: Wastewater treated by the multi-stage filtration system overflows into the water neutralization system.

[0085] Furthermore, the water neutralization system is equipped with an agitator, and the agitator motor rotates at 200 r / min; the pH adjuster is citric acid, and the dosage is 1600 mg / L; the treated wastewater is discharged from the system by overflow or pump pressurization, and the treated wastewater can be reinjected or used to prepare drilling and fracturing fluids.

[0086] Table 1 Data Comparison Table

[0087]

[0088] As shown in Table 1, after treatment with this process, the COD removal rate of the wastewater in both embodiments exceeded 90%. The viscosity of the wastewater also decreased significantly, the total hardness was less than or equal to 300 mg / L, and the turbidity of the treated wastewater was less than 20 NTU. This indicates that the wastewater treatment in both embodiments achieved significant results.

[0089] Example 3

[0090] For the waste liquid in Example 2, the input vector of the model for the micro-electrolysis oxidation system is optimized according to the matching algorithm, namely pH, micro-electrolysis material dosage, reaction time, aeration rate, and the output is wastewater viscosity.

[0091] The first step is to input the data matrix X, which has a dimension of m×4, where m is the number of samples.

[0092] Furthermore, the input matrix is:

[0093]

[0094] The second step, the expression under the model's assumptions, is:

[0095]

[0096] in, Let ω be the objective function and ω be the weight vector.

[0097] The third step is to handle the upper and lower bound errors as follows:

[0098]

[0099] The fourth step is to optimize the solution of the dual problem, that is, to solve it according to equation (2) and equation (3), by adjusting ω, b, and ξ. i and ξ i * Differentiate and set it to zero:

[0100]

[0101] Furthermore, based on equation (10), the final regression function is obtained:

[0102]

[0103] Based on formulas (6) to (11), a corresponding prediction model was constructed. The model was then used to perform regression prediction using MATLAB software. When the micro-electrolysis reaction time was 60 min, the pH of the wastewater was 4, 120 kg of micro-electrolysis material was added to each cubic meter of wastewater, and the ratio of aeration to wastewater was 10:1, the predicted viscosity was 1.46 mPa·s, and the actual viscosity after treatment was 1.48 mPa·s. The relative error was only 1.35%, which proved that the model had high accuracy, improved the flexibility of the process, increased the treatment efficiency, reduced the amount of reagents used, and thus saved treatment costs.

[0104] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0105] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A drilling and reservoir stimulation waste fluid treatment system, characterized in that, include: The system comprises a sequentially connected oil removal system, a micro-electrolysis oxidation system, a pH adjustment system, an ion removal system, a coagulation and inclined plate sedimentation system, a multi-stage filtration system, and a water neutralization system. The oil removal system treats the waste liquid to remove oil; the micro-electrolysis oxidation system adjusts the pH of the oil-removed waste liquid and performs electrolytic oxidation; the pH adjustment system performs secondary pH adjustment on the electrolytically oxidized waste liquid; and the ion removal system removes ions from the waste liquid after the secondary pH adjustment. The coagulation and inclined plate sedimentation system performs coagulation and flocculation treatment and sedimentation on the waste liquid after ion removal treatment to achieve solid-liquid separation. The waste liquid after solid-liquid separation is then subjected to multi-stage filtration and water neutralization system for multi-stage filtration and pH adjustment three times to meet the discharge standards. In the micro-electrolysis oxidation system, the waste liquid after oil removal treatment enters the system from the bottom via overflow. The pH value is adjusted by adding a pH adjuster, and electrolysis oxidation occurs through micro-electrolysis materials, while aeration promotes the oxidation reaction. The micro-electrolysis reaction time is 40-100 min; the pH of the waste liquid is adjusted to 3-4; the porosity of the micro-electrolysis materials is 60-80%; 40-160 kg of micro-electrolysis materials are added per cubic meter of waste liquid; the aeration rate to waste liquid ratio is 6:1-12:1; and the waste liquid viscosity is 1-8 mPa·s. The micro-electrolysis oxidation system predicts the effluent viscosity of the waste liquid using a preset algorithm. Specifically, a training set is established using pH, micro-electrolysis material dosage, reaction time, aeration rate, and waste liquid viscosity as training samples. pH, micro-electrolysis material dosage, reaction time, and aeration rate are inputs, and waste liquid viscosity is the output. The usage of the input parameters of the micro-electrolysis oxidation system is adjusted based on the predicted effluent viscosity, specifically including: Suppose the given training samples are a set of m samples in an (n+1)-dimensional space. T ={( x 1, y 1),( x 2, y 2),…,( x i , y i ),…,( x m , y m )}, x i ∈R n It is the input vector. y i ∈R is the output value; This algorithm is used to find a suitable regression function. f ( x The regression function formula is as follows: (1) in, x It is the input vector; g ( ) is a mapping function; ω It is a weight vector; b It is a threshold; The regression prediction problem is transformed into an optimization problem of solving a quadratic programming problem, as shown in the formula: (2) in, ε Insensitive function; c As a penalty factor; ξ i and ξ i These are slack variables; By using kernel functions to map the above optimization problem to a higher-dimensional space, we obtain the dual problem of this problem, as shown in the formula: (3) in, L Let be the objective function. 、 For the first i A training sample Lagrange multiplier, 、 For the first j One training sample Lagrange multiplier; K(x i ，x j ) For kernel functions; K ( ) uses a radial basis kernel function, the basic form of which is shown in equation (4): (4) in, γ It is a regularization parameter; By solving this dual problem, the final regression function can be obtained, which is: (5) in, n m It is the number of vectors. and For Lagrange multipliers; b The threshold value is used.

2. The drilling and reservoir stimulation waste fluid treatment system according to claim 1, characterized in that, The oil removal system consists of a coalescing oil separator, and the oil content in the waste liquid after treatment by the coalescing oil separator is 0~50mg / L.

3. The drilling and reservoir stimulation waste fluid treatment system according to claim 1, characterized in that, The pH adjustment system is equipped with an alkaline solvent of 300-1000 mg / L to maintain the pH of the waste liquid at 8-9. The pH adjustment system is equipped with an aeration device, which is kept running while sodium hydroxide is added. The ratio of aeration volume to waste liquid is 6:1 to 12:

1. The aeration time is 20-40 min.

4. The drilling and reservoir stimulation waste fluid treatment system according to claim 1, characterized in that, In the ion removal system, the waste liquid enters the system from the bottom via overflow, and the dosage of the ion removal agent is 1000~3500 mg / L. The ion removal agent is a compound agent composed of agent A, agent B, and auxiliary agents, including agent A (10% sodium sulfate, 5% aluminum sulfate, and 5% potassium carbonate), agent B (50% sodium carbonate), and auxiliary agent (30% bentonite). The ion removal system is equipped with a stirring paddle, and the stirring motor rotates at 100~400 r / min. The residence time of the waste liquid in the ion removal system is 20~40 min.

5. The drilling and reservoir stimulation waste fluid treatment system according to claim 1, characterized in that, The coagulation and inclined plate settling system includes a coagulation tank and an inclined plate settling tank. Wastewater treated by ion removal overflows into the coagulation tank from the bottom. The coagulation tank is divided into two chambers, A and B. Wastewater overflows into chamber A from the bottom. Chamber A is supplemented with 300-1000 mg / L of PAC and is equipped with an agitator with a motor speed of 300-600 r / min. The residence time of the wastewater in chamber A is 10-20 min. Wastewater overflows into chamber B from the bottom. Chamber B is supplemented with 10-40 mg / L of PAM and is equipped with an agitator with a motor speed of 100-240 r / min. The residence time of the wastewater in chamber B is also 10-20 min. The coagulated wastewater then overflows into the inclined plate settling tank for sludge settling. The residence time of the wastewater in the inclined plate settling tank is 60-150 min.

6. The drilling and reservoir stimulation waste fluid treatment system according to claim 1, characterized in that, In the multi-stage filtration system, the waste liquid overflowing from the coagulation and inclined plate sedimentation system is pressurized by a pump and then enters the multi-stage filtration system. The multi-stage filtration system consists of anthracite, glass fiber, and polyester fiber from top to bottom. The residence time of the waste liquid in the multi-stage filtration system is 30 to 60 minutes.

7. The drilling and reservoir stimulation waste fluid treatment system according to claim 1, characterized in that, In the water neutralization system, the waste liquid after being treated by the multi-stage filtration system enters the water neutralization system by overflow. The water neutralization system is equipped with a stirring paddle, and the stirring motor rotates at a speed of 100~400 r / min. The pH adjuster is citric acid, and its dosage is 1000~2300 mg / L. The treated waste liquid exits the system by overflow or by pump pressurization.

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