Pretreatment agent as well as preparation method and application thereof

Abstract

The invention relates to a pretreating agent as well as a preparation method and application thereof. The pretreatment agent is prepared from the following raw material components: cationic polyacrylamide, poly dimethyl diallyl ammonium chloride, 1-hydroxyethylidene-1, 1-diphosphonic acid, xanthan gum, potassium chloride, chitosan, acetic acid and a solvent, wherein the content of the cationic polyacrylamide is 0.7%-0.9% in percentage by mass, the content of the poly dimethyl diallyl ammonium chloride is 1.5%-3.0% in percentage by mass, the content of the hydroxyethylidene diphosphate is 25.3%-39.4% in percentage by mass, the content of the xanthan gum is 0.08%-0.15% in percentage by mass, the content of the potassium chloride is 0.08%-0.15% in percentage by mass, the content of the chitosan is 0.04%-0.06% in percentage by mass, and the balance of water. The content of the acetic acid is 2.0%-3.0%. The pretreatment agent improves the oil removal effect of a heavy crude oil sewage physicochemical process, is used for a heavy crude oil sump oil dehydration process, and realizes three-phase separation of oil, water and mud.

Description

Technical Field

[0001] The present application relates to the technical field of heavy crude oil wastewater treatment, and in particular to a pretreatment agent and a preparation method and application thereof. Background Art

[0002] As oilfield exploitation enters the middle stage, the water content of the produced crude oil is as high as 60-85%, while that of heavy oil and extra heavy oil can reach more than 95%. After oil-water separation, a large amount of oily wastewater and dirty oil containing a large amount of wastewater are produced. Both the oil and water phases contain a high content of nano-micron colloidal particles, the main components of which are petroleum, suspended mud and sand particles, organic matter, and various oilfield chemical additives added in the early stage (such as water plugging and profile control agents, viscosity reducers, plugging removers, sand inhibitors, wax removal agents, etc.). After separation, whether it is sewage or dirty oil, the state is extremely stable. The difficulty of water purification and dirty oil dehydration is relatively high, and it is difficult to achieve the purpose of water purification and dirty oil dehydration with existing technology.

[0003] At present, the oil-water separation agents for heavy crude oil wastewater are pretreatment agents or reverse pretreatment agents used in the field of conventional crude oil wastewater, and the effect is not ideal. The oil-water separation is not complete, and mud and oil are mixed. The density of the waste oil is further increased, and the mud-water separation is not complete. Secondary separation is required by "polymerization" and "polymer bridging mechanism". Summary of the invention

[0004] The present application provides a pretreatment agent and a preparation method and application thereof, so as to solve the technical problem that the existing heavy crude oil separation agent has a poor separation effect.

[0005] In a first aspect, the present application provides a pretreatment agent, wherein the raw material components of the pretreatment agent include:

[0006] Cationic polyacrylamide, polydimethyldiallylammonium chloride, hydroxyethylene diphosphoric acid, xanthan gum, potassium chloride, chitosan, acetic acid and solvent; wherein, by mass fraction,

[0007] The content of the cationic polyacrylamide is 0.7% to 0.9%, the content of the polydimethyldiallylammonium chloride is 1.5% to 3.0%, the content of the hydroxyethylene diphosphoric acid is 25.3% to 39.4%, the content of the xanthan gum is 0.08% to 0.15%, the content of the potassium chloride is 0.08% to 0.15%, the content of the chitosan is 0.04% to 0.06%, and the content of the acetic acid is 2.0% to 3.0%.

[0008] Optionally, the content of the cationic polyacrylamide is 0.8% to 0.9%, the content of the polydimethyldiallylammonium chloride is 1.7% to 2.5%, the content of the hydroxyethylene diphosphoric acid is 28.9% to 35.1%, the content of the xanthan gum is 0.09% to 0.13%, the content of the potassium chloride is 0.09% to 0.13%, the content of the chitosan is 0.04% to 0.05%, and the content of the acetic acid is 2.0% to 2.5%.

[0009] Optionally, the content of the cationic polyacrylamide is 0.9%, the content of the polydimethyldiallylammonium chloride is 2.4%, the content of the hydroxyethylene diphosphoric acid is 29.6%, the content of the xanthan gum is 0.09%, the content of the potassium chloride is 0.09%, the content of the chitosan is 0.04%, and the content of the acetic acid is 2.0%.

[0010] Optionally, the solvent is water.

[0011] In a second aspect, the present application provides the use of the pretreatment agent described in any one of the first aspects in separating heavy crude oil wastewater.

[0012] In a third aspect, the present application provides a method for preparing a pretreatment agent, for preparing the pretreatment agent according to any one of the first aspects of claim 1, the method comprising:

[0013] Prepare a mixed solution of xanthan gum and potassium chloride;

[0014] preparing a mixed solution of chitosan and acetic acid;

[0015] The hydroxyethylene diphosphoric acid, the mixed solution of chitosan and acetic acid, the mixed solution of xanthan gum and potassium chloride, polydimethyldiallylammonium chloride, cationic polyacrylamide and solvent are stirred and mixed to obtain a pretreatment agent.

[0016] Optionally, in the mixed solution of xanthan gum and potassium chloride, the weight content of the xanthan gum is 0.8% to 1.0%, and the weight content of the potassium chloride is 0.7% to 1.1%.

[0017] Optionally, in the mixed solution of xanthan gum and potassium chloride, the weight content of xanthan gum is 0.8%, and the weight content of potassium chloride is 0.8%.

[0018] Optionally, in the mixed solution of chitosan and acetic acid, the weight ratio of the chitosan to the acetic acid is 1:(63-79).

[0019] Optionally, in the mixed solution of chitosan and acetic acid, the weight ratio of the chitosan to the acetic acid is 1:63.

[0020] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0021] The pretreatment agent provided in the embodiment of the present application is an oil, mud, and water three-phase pretreatment agent (separation agent) with the purpose of efficient oil removal and mud removal of heavy crude oil wastewater. In order not to increase the difficulty of oil-water separation, that is, not to increase the specific gravity of heavy crude oil wastewater, and at the same time reduce the specific gravity of heavy crude oil wastewater after removing some mechanical impurities, the quaternary ammonium root of organic matter in the medium is selected as the demulsification core, and the high molecular weight carbon chain of medium and low molecular weight is used as the operation connection framework. The pretreatment agent not only accelerates the separation of oil and water phases, but also can make the emulsified state of water-in-oil (O / W) or oil-in-water (W / O) or the complex emulsification system of oil and water layers interlaced rapidly demulsify, and the oil droplets and water droplets are condensed respectively, and quickly separated, which is conducive to the floating recovery of the waste oil. The mechanical impurities in the oil-water two-phase and the suspended inorganic matter such as mud and sand form large and solid flocs, sink quickly, and show a three-layer separation mode of upper waste oil, middle wastewater and lower bottom mud from a macroscopic point of view. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0023] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0024] Figure 1 A schematic diagram of a process for preparing a pretreatment agent provided in an embodiment of the present application;

[0025] Figure 2 A schematic diagram of a production process of a heavy crude oil wastewater pretreatment agent provided in an embodiment of the present application;

[0026] Figure 3 A process flow chart of a sewage treatment system and a gathering and dehydration system for applying a heavy crude oil sewage pretreatment agent provided in an embodiment of the present application;

[0027] Figure 4 A heavy crude oil wastewater pretreatment agent is provided in an embodiment of the present application to expand the heavy crude oil wastewater dehydration process flow chart. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0029] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0030] In the present application, in the absence of any contrary description, the directional words used, such as "upper" and "lower", are specifically the directions of the drawings in the accompanying drawings. In addition, in the description of the present specification, the terms "including", "comprising", etc. refer to "including but not limited to". In this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of the associated objects, indicating that there may be three relationships, for example, A and / or B, which can represent: A exists alone, A and B exist at the same time, and B exists alone. Wherein A, B can be singular or plural. In this article, "at least one" refers to one or more, and "plural" refers to two or more. "At least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of singular or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, a~b (i.e. a and b), a~c, b~c, or a~b~c, where a, b, c can be single or plural, respectively.

[0031] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0032] In a first aspect, the present application provides a pretreatment agent, wherein the raw material components of the pretreatment agent include:

[0033] Cationic polyacrylamide, polydimethyldiallylammonium chloride, hydroxyethylene diphosphoric acid, xanthan gum, potassium chloride, chitosan, acetic acid and solvent; wherein, by mass fraction,

[0034] The content of the cationic polyacrylamide is 0.7% to 0.9%, the content of the polydimethyldiallylammonium chloride is 1.5% to 3.0%, the content of the hydroxyethylene diphosphoric acid is 25.3% to 39.4%, the content of the xanthan gum is 0.08% to 0.15%, the content of the potassium chloride is 0.08% to 0.15%, the content of the chitosan is 0.04% to 0.06%, and the content of the acetic acid is 2.0% to 3.0%.

[0035] In the embodiments of the present application, in view of the reality that the density of dirty oil and water in heavy crude oil wastewater is close, the oil-water mixture is seriously emulsified, the oil and water are difficult to separate, and the mechanical impurities / suspended solids are too high. At the same time, the current process technology cannot achieve the simultaneous separation of oil, mud and water. The dirty oil contains too many impurities, which makes the density further close to water, and the oil and water phases are more difficult to separate. Therefore, an efficient and special heavy crude oil wastewater pretreatment agent is developed to improve the oil removal effect of the physicochemical process of heavy crude oil wastewater, and it can be used in the dehydration process of heavy crude oil-type dirty oil, and the three-phase separation of oil, water and mud is achieved.

[0036] Among the above raw material components, cationic polyacrylamide is a cationic medium molecular weight polymer, which plays a role of polymer bridging in the dehydration process of heavy-based waste oil; the positive effect of controlling the content of cationic polyacrylamide to 0.7% to 0.9% is: ensuring the polymer content required for the separation of the three-phase interface of oil, mud and water, forming an appropriate number of bridging polymers, and providing a suitable separation carrier for the three-phase separation. If the content of the cationic polyacrylamide is too high, it will cause the water phase to form too many surfactants to a certain extent, which is not easy to treat the subsequent water quality; if the content of the cationic polyacrylamide is too low, it will cause the oil and mud phases to be incompletely separated from the water to a certain extent, affecting the separation effect. Specifically, the content of the cationic polyacrylamide can be 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, etc.

[0037] Polydimethyldiallyl ammonium chloride has demulsification and coagulant effects; the content of polydimethyldiallyl ammonium chloride is controlled so that the oil and mud in the water phase are fully separated, and at the same time, extremely small particles are formed to provide a basis for the next step of polymer bridging separation. If the content of the polydimethyldiallyl ammonium chloride is too high, a transitional emulsification effect will be formed to a certain extent, inhibiting the polymer bridging separation effect.; If the content of the polydimethyldiallyl ammonium chloride is too low, it will affect the degree of separation of oil and mud in the water phase to a certain extent. Specifically, the content of the polydimethyldiallyl ammonium chloride can be 1.5%, 1.8%, 2.1%, 2.4%, 2.8%, 3.0%, etc.

[0038] As a stabilizer in the heavy crude oil wastewater pretreatment agent system, hydroxyethylene diphosphoric acid has both demulsification function and polymerization efficiency; the content of hydroxyethylene diphosphoric acid is controlled to ensure that the mud phase is smoothly separated from the water phase and the oil phase, and to avoid mud mixing with oil and water. If the content of hydroxyethylene diphosphoric acid is too high, it will be difficult to form a joint reaction with the polymer to a certain extent, and the reaction of the polymer will be delayed, resulting in the expansion of the polymer in the water body; if the content of hydroxyethylene diphosphoric acid is too low, the demulsification and separation effect of the three phases of oil, mud and water will be reduced to a certain extent. In particular, the degree of secondary separation of the mud phase in the oil phase is weakened. Specifically, the content of hydroxyethylene diphosphoric acid can be 25.3%, 27%, 29%, 31%, 33%, 35%, 37%, 39.4%, etc.

[0039] The role of xanthan gum: to ensure the stability and adaptability of the preparation during use, especially in harsh environments such as strong alkali and concentrated salt; to control the content of xanthan gum, and to use it in combination with organic polymers in normal environments, and to serve as the main connecting bridge between organic polymers and separated impurities to form small particle agglomerates in strong alkali or concentrated salt environments. If the content of xanthan gum is too high, it will affect the effective dissolution amount of other components of the preparation to a certain extent, and make the preparation too viscous; if the content of xanthan gum is too low, it will affect the use effect and separation efficiency of the preparation in strong alkali or concentrated salt environments to a certain extent. Specifically, the content of xanthan gum can be 0.08%, 0.10%, 0.12%, 0.14%, 0.15%, etc.

[0040] The role of potassium chloride: accelerate the dissolution rate of xanthan gum in water; control the content of potassium chloride and use it in conjunction with xanthan gum to form the best dissolution ratio and dissolution rate of xanthan gum. If the content of potassium chloride is too high, it will cause ineffective investment of potassium chloride to a certain extent, resulting in waste; if the content of potassium chloride is too low, it will reduce the dissolution rate of xanthan gum to a certain extent, and cause the xanthan gum to be unable to dissolve completely. Specifically, the content of potassium chloride can be 0.08%, 0.10%, 0.12%, 0.14%, 0.15%, etc.

[0041] The role of chitosan: It plays a flocculating role in oil-water separation and mud-water separation, aggregates with oil and mud to form fine particles, and forms oil and mud through organic polymer bridges. It has a significant flocculating effect on sewage with a high degree of emulsification. Control the content of chitosan to ensure that the oil droplets and mud residue have enough condensation cores to make the three phases fully separated. If the content of chitosan is too high, the mud phase will be dispersed to a certain extent, and the water phase will be turbid at the same time. If the content of chitosan is too low, it will be difficult to completely eliminate the emulsified state of oil and mud to a certain extent, and the oil and mud phases will still remain in the water. Specifically, the content of hydroxyethylene diphosphoric acid can be 0.04, 0.045, 0.05, 0.055, 0.06, etc.

[0042] The role of acetic acid: dissolve chitosan and serve as a supplement to hydroxyethylidene diphosphoric acid; control the content of acetic acid to ensure the full dissolution of chitosan and increase the dissolution rate of the acetic acid-chitosan mixture in the overall preparation. If the content of acetic acid is too high, it will cause a waste of acetic acid to a certain extent; if the content of acetic acid is too low, it will cause insufficient dissolution of chitosan to a certain extent, slowing down the dissolution rate of the acetic acid-chitosan mixture in the overall preparation. Specifically, the content of acetic acid can be 2.0%, 2.3%, 2.5%, 2.8%, 3.0%, etc.

[0043] Function of solvent: As the core solvent of this preparation, it is easy to use and all components can be fully dissolved.

[0044] In some embodiments, the content of the cationic polyacrylamide is 0.8% to 0.9%, the content of the polydimethyldiallylammonium chloride is 1.7% to 2.5%, the content of the hydroxyethylene diphosphoric acid is 28.9% to 35.1%, the content of the xanthan gum is 0.09% to 0.13%, the content of the potassium chloride is 0.09% to 0.13%, the content of the chitosan is 0.04% to 0.05%, and the content of the acetic acid is 2.0% to 2.5%.

[0045] Preferably, the content of the cationic polyacrylamide may be 0.8% to 0.9%, the content of the polydimethyldiallylammonium chloride may be 1.7% to 2.5%, the content of the hydroxyethylene diphosphoric acid may be 28.9% to 35.1%, the content of the xanthan gum may be 0.09% to 0.13%, the content of the potassium chloride may be 0.09% to 0.13%, the content of the chitosan may be 0.04% to 0.05%, and the content of the acetic acid may be 2.0% to 2.5%.

[0046] In some embodiments, the content of the cationic polyacrylamide is 0.9%, the content of the polydimethyldiallylammonium chloride is 2.4%, the content of the hydroxyethylene diphosphoric acid is 29.6%, the content of the xanthan gum is 0.09%, the content of the potassium chloride is 0.09%, the content of the chitosan is 0.04%, and the content of the acetic acid is 2.0%.

[0047] More preferably, the content of the cationic polyacrylamide can be 0.9%, the content of the polydimethyldiallylammonium chloride can be 2.4%, the content of the hydroxyethylene diphosphoric acid can be 29.6%, the content of the xanthan gum can be 0.09%, the content of the potassium chloride can be 0.09%, the content of the chitosan can be 0.04%, and the content of the acetic acid can be 2.0%.

[0048] In some embodiments, the solvent is water.

[0049] In the embodiments of the present application, water is used as the solvent, which has the following positive effects: the solvent is economical, practical, widely used, and each component can be dissolved under the necessary conditions. Preferably, pure water or deionized water is used.

[0050] This pretreatment agent is a comprehensive agent for dehydration of heavy crude oil wastewater and treatment of initial oil production wastewater, integrating demulsification, coagulation and flocculation. After a certain amount is added to the heavy oil wastewater, its linear straight chain and branched chain rapidly extend within different degrees, quickly neutralize the negative charge on the surface of the colloidal particles and emulsified oil in the wastewater, compress the double electric layer of the micelle and adsorb on the surface of the colloid. With the destruction of the double electric layer, the repulsive potential of the emulsified oil micelle disappears, the micelles collide with each other, agglomerate and gradually separate from the water, thereby achieving the purpose of efficient dehydration of heavy crude oil wastewater and initial purification of water quality.

[0051] The pretreatment agent is light yellow or slightly brown, a liquid viscous preparation, with a pH value of 5.5-6.5 and a density of 1.17-1.25 mg / cm 3 It has a certain acidic irritation. The finished product is not recommended to be stored for more than 15 days. It is recommended to use diluted drugs below 50% concentration within 24 hours.

[0052] The pretreatment agent has at least the following advantages: it is used in special wastewater deoiling processes such as coal tar, refinery wastewater, and coking wastewater; it can be expanded to be used in conventional wastewater deoiling processes such as domestic sewage and light crude oil wastewater for deoiling and degreasing; it can be expanded to be used in heavy crude oil waste oil dehydration and conventional waste oil dehydration as well as coal tar waste oil dehydration processes; it is not limited by process conditions and can be used as a deoiling chemical agent in processes such as vertical flow deoiling tanks, central reaction cylinder deoiling tanks, horizontal flow oil separators, and inclined plate oil separators; it is not limited by the material of equipment and facilities and can be used in processes of various materials such as steel structures, concrete structures, oleophilic and hydrophobic bases, and hydrophilic and oleophobic bases as a supporting agent; the specific gravity of the separated waste oil is reduced, which is conducive to flotation separation; the three-phase separation of oil, mud, and water can be achieved; the petroleum content of the separated wastewater can be lower than 100 mg / L; the separated The mechanical impurities in the waste oil can be less than 3%; it can be directly used in the heavy oil wastewater deoiling process, eliminating the heating stage and reducing the operating cost; it can be expanded to be applied to the waste oil sludge separation process with a relatively high water content (water content > 76%), and the three-phase separation of oil, sludge and water can be achieved simultaneously, and the effluent can be regarded as pretreated; the pretreatment agent has complex ingredients, but stabilizes the main ingredients in a complex form without affecting their effects, and is easy to produce and has a stable preparation; the pretreatment agent operates in a slightly acidic environment to accelerate the reaction time, and the organic polymer acid has low corrosion to the equipment, which is conducive to industrial application; the core components of the pretreatment agent can be adjusted according to the results of simulation tests to facilitate the dehydration effect of various types and grades of heavy crude oil waste oil; the core components of the pretreatment agent are based on the relevant safety technical instructions, and there are no components that are difficult to biodegrade, and they can all be biodegraded, and are green composite preparations.

[0053] In a second aspect, the present application provides the use of the pretreatment agent described in any one of the first aspects in separating heavy crude oil wastewater.

[0054] The application of the above-mentioned pretreatment agent in separating heavy crude oil wastewater can be applied to special wastewater oil removal processes such as coal tar, refining wastewater, and coking wastewater; it can be expanded to conventional wastewater oil removal processes such as domestic sewage and light crude oil wastewater for oil and grease removal.

[0055] Specifically, see Figure 3 The process flow chart of the sewage treatment system and the gathering and dehydration system for the application of the heavy crude oil sewage pretreatment agent is shown. Working process: Add an appropriate proportion of heavy crude oil sewage pretreatment agent to the sewage treatment / gathering and separation system heavy crude oil / heavy oil sewage, enter the separation device, and separate the oil, mud and water. The petroleum content in the water does not exceed 120mg / L, and the water content in the heavy crude oil / heavy oil is less than 5%. If the standard is not met, adjust the proportion of each component, conduct simulation experiments, establish the regression coefficient, control the concentration of the dosing, and finally meet the requirements.

[0056] See also Figure 4The heavy crude oil wastewater pretreatment agent shown in the figure expands the heavy crude oil wastewater dehydration process flow chart. Working process: According to the waste oil and wastewater conditions, when the liquid phase temperature is above 63°C (the optimal critical temperature for dehydration of heavy crude oil-based waste oil) (the process environment does not reach 63°C, additional heating equipment is required), add a new heavy crude oil wastewater pretreatment agent to the heavy crude oil wastewater and water mixture, with a dosage concentration of 20-80mg / L, and react in the oil-water separation device (it is recommended to use an inclined plate structure) / centrifugal separation device (it is recommended to use a three-phase centrifugal separator) for 25-40 minutes (i.e.: water residence time), and reactions such as demulsification, electrical neutralization, and flocculation occur, and then dissolved in compressed air (25-40L / min, air pressure 0.5-0.8MPa) accelerates oil-water separation (centrifugal separation device does not need to add additional compressed air, and the centrifugal frequency is greater than 400r / min). The oil and water are initially separated by the oil-water separation device, and more than 95% of the heavy crude oil is removed from the sewage, while the petroleum in the sewage does not exceed 120mg / L, and the sedimentation of the oily sludge (mainly containing mechanical impurities) is more than 80%. If the dehydration effect does not meet the relevant requirements, a simulation test is carried out to establish the regression coefficient, and the optimal component ratio in the agent and the optimal agent dosage ratio are adjusted before use.

[0057] Heavy crude oil wastewater and dirty oil are complex in nature, extremely stable, and have certain cross-influences. Experiments and field operations have shown that when heavy crude oil dirty oil is mixed with conventional crude oil by more than 2.5%, the dehydration effect of conventional crude oil is also unstable. The liquid production ratio of heavy oil wastewater to conventional crude oil wastewater is basically 2:1. Mixing at this ratio will cause the problem that conventional crude oil wastewater will also become heavy oil wastewater. At the same time, for the heavy crude oil wastewater oil removal process and heavy crude oil wastewater dehydration process, it is difficult to achieve effective dehydration by simple chemical or physical methods, and a combination of the two must be adopted for dehydration treatment.

[0058] The technical solutions for the heavy crude oil wastewater oil removal process (heavy crude oil waste oil dehydration process) all utilize the high temperature waste heat environment of the heavy oil gas injection thermal recovery process, without the need for secondary heating, and add a new heavy crude oil wastewater pretreatment agent into the stirring or centrifugal device to achieve efficient oil removal from heavy crude oil wastewater (heavy crude oil waste oil dehydration).

[0059] According to the situation of dirty oil and sewage, when the liquid phase temperature is above 63℃ (critical temperature for deoiling heavy crude oil sewage and dehydrating heavy crude oil sewage) (if the process environment does not reach 63℃, additional heating equipment is required), add a new type of heavy crude oil sewage pretreatment agent to the heavy crude oil oil-water mixture, with a dosing concentration of 20-80mg / L (according to the simulation test results, the optimal dosing concentration can exceed this range), and react in the oil-water separation device (it is recommended to use an inclined plate structure) / centrifugal separation device (it is recommended to use a three-phase centrifugal separator) for 25-40 minutes (i.e., water residence time) to cause demulsification-electrical neutralization-flocculation Wait for reaction, then dissolve in compressed air (25-40L / min, air pressure 0.5-0.8MPa) to accelerate oil-water separation (centrifugal separation device does not need additional compressed air, centrifugal frequency is greater than 400r / min), the oil and water are initially separated by the oil-water separation device, more than 95% of heavy crude oil wastewater is removed, and the oil content in the wastewater does not exceed 120mg / L, and the sedimentation of dirty oil sludge (mainly containing mechanical impurities) is more than 80%. If the dehydration effect does not meet the relevant requirements, a simulation test is carried out to establish the regression coefficient, and the optimal component ratio in the agent and the optimal agent dosage ratio are adjusted before use.

[0060] Drug preparation equipment: dissolving tank / reactor (with stirring device), gravity / pressure / water pump dosing equipment, heating and temperature control equipment, etc. Drug use equipment: drug dispensing / dosing device, oil-water separation (with stirring and gas adding device) / three-phase centrifugal separation device, connecting pipeline, water volume control valve, gas volume control valve, etc.

[0061] In a third aspect, the present application provides a method for preparing a pretreatment agent, see Figure 1 , used to prepare the pretreatment agent according to any one of the first aspects of claim 1, the method comprising:

[0062] S1. preparing a mixed solution of xanthan gum and potassium chloride;

[0063] Add tap water or purified water or deionized water to the dissolving device, turn on the stirring device, and add xanthan gum. Xanthan gum has extremely strong hydrophilicity, so avoid adding it directly, which will cause the outer layer to absorb water and swell into a floc, thereby preventing water from entering the inner layer. Before preparation, mix potassium chloride powder and xanthan gum powder evenly, and slowly add it to the stirring water. The prepared xanthan gum and potassium chloride solution should be set aside for use.

[0064] S2, preparing a mixed solution of chitosan and acetic acid;

[0065] Add 2% acetic acid solution into the dissolving device, add chitosan according to the proportion, stir evenly to form chitosan acetic acid solution, the pH value of the acetic acid solution is below 6.5, and the prepared chitosan acetic acid solution is placed for use.

[0066] S3, stirring and mixing hydroxyethylene diphosphoric acid, a mixed solution of chitosan and acetic acid, a mixed solution of xanthan gum and potassium chloride, polydimethyldiallylammonium chloride, cationic polyacrylamide and a solvent to obtain a pretreatment agent.

[0067] Start the pure water dosing device, after adding pure water, control the water temperature at 25-30℃, add hydroxyethylene diphosphoric acid, turn on the stirring device (anti-corrosion treated, non-blade type, to reduce stirring shear force), control the frequency to 110-150r / min, stop adding (dosing time does not exceed 5min), control the stirring time to 8-12min, and measure the pH value to 2.5-4.0.

[0068] Start the chitosan acetic acid mixed solution adding device, control the stirring frequency to 110-150r / min, stop adding (addition time does not exceed 5min), control the stirring time to 8-10min, and measure the pH value to 3.0-4.5.

[0069] Turn on the xanthan gum and potassium chloride mixed solution adding device, stirring frequency 110-150r / min, stop adding (addition time does not exceed 5min), control stirring time 8-10min, measure pH value 3.0-4.5.

[0070] Start the polydimethyldiallyl ammonium chloride dosing equipment (the stirring device continues to run), raise the temperature to 32-38°C, add polydimethyldiallyl ammonium chloride, stop adding (the adding time does not exceed 10 minutes), adjust the stirring frequency to 170-220r / min, and control the stirring time to 15-20min.

[0071] Keep the water temperature at 32-38℃ (not to exceed the critical temperature of 40℃ for the decomposition of cationic polyacrylamide in water phase), turn on the cationic polyacrylamide dosing device, and add the cationic polyacrylamide slowly and evenly according to the vortex. The dosing time should not be less than 15min. After stopping the dosing, adjust the stirring frequency to 190-230r / min, and control the stirring time to 25-30min. After the agent forms a homogeneous viscous colloid (latex), it can be barreled. Specifically, this pretreatment agent is used as a pretreatment agent for heavy crude oil wastewater. Please refer to Figure 2 The schematic diagram of the production process of heavy crude oil wastewater pretreatment agent shown in the figure, process pressure: standard atmospheric pressure; equipment: dissolution tank / reactor (stainless steel material or lined with ceramic or polytetrafluoroethylene corrosion-resistant coating); conveying device: powder solid conveying device and corrosion-resistant liquid conveying device; reagent solvent: tap water or purified water or deionized water.

[0072] In some embodiments, in the mixed solution of xanthan gum and potassium chloride, the weight content of xanthan gum is 0.8% to 1.1%, and the weight content of potassium chloride is 0.7% to 1.1%.

[0073] In some embodiments, in the mixed solution of xanthan gum and potassium chloride, the weight content of xanthan gum is 0.8%, and the weight content of potassium chloride is 0.8%.

[0074] The function of the mixed solution of xanthan gum and potassium chloride is to separate particle drag and suspend agents, stabilize various particulate matter separated from the water body, avoid mixing of oil and mud phases, and reduce the difficulty of separation.

[0075] Control the weight content of xanthan gum. In the state of conventional heavy oil wastewater, it will work synchronously with cationic polyacrylamide to play a superimposed amplification role; in strong alkali or high-salt wastewater, it will play a role in linking cationic polyacrylamide and restoring the polymer bridging effect. If the weight content of the xanthan gum is too high, to a certain extent, there will be xanthan gum residue in the water phase of the strong alkali or concentrated salt environment, which will change the surface tension of the water phase, resulting in the thickening of the water phase and increasing the difficulty of subsequent treatment; if the weight content of the xanthan gum is too low, to a certain extent, the oil droplets and mud residues formed by the incomplete reaction of cationic polyacrylamide in the water phase of the strong alkali or concentrated salt environment cannot be secondary coalesced, resulting in incomplete separation of the three phases of oil, mud and water. Control the weight content of potassium chloride to fully dissolve the xanthan gum and ensure that the xanthan gum has the necessary dissolution rate for industrial use. Specifically, in the mixed solution of xanthan gum and potassium chloride, the weight content of xanthan gum can be 0.8%, 0.9%, 1.0%, 1.1%, etc., and the weight content of potassium chloride can be 0.7%, 0.8%, 0.9%, 1.0%, etc.

[0076] Preferably, in the mixed solution of xanthan gum and potassium chloride, the weight content of the xanthan gum is 0.8%, and the weight content of the potassium chloride is 0.8%.

[0077] In some embodiments, in the mixed solution of chitosan and acetic acid, the weight ratio of the chitosan to the acetic acid is 1:(63-79).

[0078] In some embodiments, in the mixed solution of chitosan and acetic acid, the weight ratio of the chitosan to the acetic acid is 1:63.

[0079] The role of the mixed solution of chitosan and acetic acid: the separation process provides sufficient electrolytes, and the natural polymers with moderate molecular weight are used to aggregate pollutants to achieve mud-water separation.

[0080] The weight ratio of chitosan to acetic acid is controlled so that chitosan can be fully dissolved in advance, so that the preparation can be accelerated during the production process of this preparation, and chitosan can be guaranteed to have sufficient coagulation ability. If the weight ratio of chitosan to acetic acid is too high, chitosan will remain in the aqueous phase to a certain extent, increasing the difficulty of water treatment and causing waste of chitosan; if the weight ratio of chitosan to acetic acid is too low, the coagulation ability of chitosan will be insufficient to a certain extent, and oil and mud will still remain in the aqueous phase. Specifically, the weight ratio of chitosan to acetic acid can be 1:63, 1:65, 1:67, 1:69, 1:73:1:77, 1:79, etc. Preferably, the weight ratio of chitosan to acetic acid can be 1:63.

[0081] The preparation method of the pretreatment agent is implemented based on the above-mentioned pretreatment agent. The specific steps of the raw material components of the pretreatment agent can refer to the above-mentioned embodiments. Since the preparation method of the pretreatment agent adopts part or all of the technical solutions of the above-mentioned embodiments, it at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be repeated here one by one.

[0082] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are usually measured according to national standards. If there is no corresponding national standard, then the conditions recommended by the manufacturer are followed.

[0083] The main component ratio of heavy crude oil wastewater pretreatment agent is used as the first process of wastewater treatment, and a heavy crude oil wastewater pretreatment process and a heavy crude oil wastewater dehydration device are established, which can treat 9300m3 of heavy crude oil wastewater per day. 3 , daily treatment of heavy crude oil and waste water mixture 240m 3 . It consists of a regulating oil removal tank (effective volume 5000m 3 ), 1 waste oil recovery tank (effective volume 250m 3 ), 1 three-phase centrifugal separator (processing capacity 10m 3 / h) 1, 2 groups of dispensing and dosing devices (12h rotation operation), first carry out the compatibility test of the reagents, calculate the regression coefficient, determine the proportion of the reagent components and the best dosing concentration, dilute the prepared heavy crude oil wastewater pretreatment agent at a ratio of 25%, add it at a concentration of 45mg / L, and the reaction time (retention time in water) is 15min. For specific process parameters, please refer to Table 1-Table 2.

[0084] Table 1 Raw material components of pretreatment agent (wt%), the rest is water

[0085]

[0086]

[0087] Table 2 Configuration of xanthan gum and potassium chloride mixed solution, configuration of chitosan and acetic acid mixed solution

[0088]

[0089] Independent experiments were conducted on steam injection thermal recovery heavy oil wastewater, SAGD high temperature separation water, and steam injection boiler tail water using the pretreatment agents of Examples 1-3. The results are shown in Table 3.

[0090] Table 3 Experimental results of pretreatment agent on steam injection thermal recovery heavy oil wastewater, SAGD high temperature separation water and steam injection boiler tail water

[0091] Serial number Heavy crude oil wastewater Water content of dirty oil Mechanical impurities content Dewatering of petroleum wastewater Example 1 Steam injection thermal recovery of heavy oil wastewater ≤2％ ≤2％ ≤15mg / L Example 2 SAGD high temperature separation water ≤5％ ≤8％ ≤25mg / L Example 3 High-salinity tail water from steam injection boiler ≤3％ ≤5％ ≤5mg / L

[0092] As shown in Table 3, the pretreatment agent can be used to separate heavy crude oil wastewater to achieve three-phase separation of oil, mud and water. It has good control over the water content of the waste oil, the content of mechanical impurities, and the petroleum indicators of the dehydrated wastewater.

[0093] The demulsifier (pre-dehydrating agent) used in the joint station of Shuguang Oil Production Plant of Liaohe Oilfield Branch was compared. The raw material components of the demulsifier (pre-dehydrating agent) include dimethylamine and epichlorohydrin. The same dose of the demulsifier and this preparation were added to the heavy oil removal liquid of the gathering and transportation system, and the comparative test was carried out. The water content of the oil phase, the mechanical impurity content of the oil phase, and the petroleum content of the water phase were tested respectively. Please refer to Table 4.

[0094] Table 4 Comparative test results of Example 3 and Comparative Example 1

[0095]

[0096]

[0097] It can be seen from Table 4 that the pretreatment agent is used to separate heavy crude oil wastewater, and the effect of oil, mud and water three-phase separation is better than that of comparative example 1.

[0098] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A pretreatment agent, characterized in that The raw material components of the pretreatment agent include: Cationic polyacrylamide, polydimethyldiallylammonium chloride, hydroxyethylene diphosphoric acid, xanthan gum, potassium chloride, chitosan, acetic acid and solvent; wherein, by mass fraction, The content of the cationic polyacrylamide is 0.7% to 0.9%, the content of the polydimethyldiallylammonium chloride is 1.5% to 3.0%, the content of the hydroxyethylene diphosphoric acid is 25.3% to 39.4%, the content of the xanthan gum is 0.08% to 0.15%, the content of the potassium chloride is 0.08% to 0.15%, the content of the chitosan is 0.04% to 0.06%, and the content of the acetic acid is 2.0% to 3.0%.

2. The pretreatment agent according to claim 1, characterized in that The content of the cationic polyacrylamide is 0.8% to 0.9%, the content of the polydimethyldiallylammonium chloride is 1.7% to 2.5%, the content of the hydroxyethylene diphosphoric acid is 28.9% to 35.1%, the content of the xanthan gum is 0.09% to 0.13%, the content of the potassium chloride is 0.09% to 0.13%, the content of the chitosan is 0.04% to 0.05%, and the content of the acetic acid is 2.0% to 2.5%.

3. The pretreatment agent according to claim 2, characterized in that The content of the cationic polyacrylamide is 0.9%, the content of the polydimethyldiallylammonium chloride is 2.4%, the content of the hydroxyethylene diphosphoric acid is 29.6%, the content of the xanthan gum is 0.09%, the content of the potassium chloride is 0.09%, the content of the chitosan is 0.04%, and the content of the acetic acid is 2.0%.

4. The pretreatment agent according to any one of claims 1 to 3, characterized in that The solvent is water.

5. Use of the pretreatment agent according to any one of claims 1 to 4 in separating heavy crude oil wastewater.

6. A method for preparing a pretreatment agent, characterized in that: For preparing the pretreatment agent according to any one of claims 1 to 4, the method comprises: Prepare a mixed solution of xanthan gum and potassium chloride; preparing a mixed solution of chitosan and acetic acid; The hydroxyethylene diphosphoric acid, the mixed solution of chitosan and acetic acid, the mixed solution of xanthan gum and potassium chloride, polydimethyldiallylammonium chloride, cationic polyacrylamide and solvent are stirred and mixed to obtain a pretreatment agent.

7. The method according to claim 6, characterized in that In the mixed solution of xanthan gum and potassium chloride, the weight content of the xanthan gum is 0.8% to 1.0%, and the weight content of the potassium chloride is 0.7% to 1.1%.

8. The method according to claim 7, characterized in that In the mixed solution of xanthan gum and potassium chloride, the weight content of xanthan gum is 0.8%, and the weight content of potassium chloride is 0.8%.

9. The method according to claim 6, characterized in that In the mixed solution of chitosan and acetic acid, the weight ratio of the chitosan to the acetic acid is 1:(63-79).

10. The method according to claim 9, characterized in that In the mixed solution of chitosan and acetic acid, the weight ratio of the chitosan to the acetic acid is 1:63.

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