CN111018198A

CN111018198A - Descaling method for oil well produced water

Info

Publication number: CN111018198A
Application number: CN202010030684.5A
Authority: CN
Inventors: 冯定; 陈文康; 周兰; 张红
Original assignee: Yangtze University
Current assignee: Yangtze University
Priority date: 2020-01-13
Filing date: 2020-01-13
Publication date: 2020-04-17

Abstract

The invention relates to a descaling method for oil well produced water, belonging to the technical field of oil well produced water treatment equipment. The descaling method for the oil well produced water has compact structure and smart design; the yield of the existing descaling device is improved by arranging the filter disc and the filter cylinder in the filter tank; the precipitate is inhibited from being redissolved by adjusting the pH value and controlling the temperature, so that the descaling effect is improved; therefore, the problems of poor descaling effect and low descaling efficiency of the existing descaling device are solved, and the requirement of enterprises on the descaling of the produced water of the oil well is met.

Description

Descaling method for oil well produced water

Technical Field

The invention relates to a descaling method for oil well produced water, belonging to the technical field of oil well produced water treatment equipment.

Background

In oil field production systems, the oil well produced water produced from an oil well is divided into three types: sodium bisulfate type, calcium chloride type and mixed type. The produced water of the calcium chloride type oil well contains more Ca²⁺And Cl^-The oil well produced water of sodium bisulfate water type contains more Na⁺And HSO₄ ^-The mixed oil well produced water contains more Ca²⁺、Cl^-、Na⁺And HSO₄ ^-. In oil well productionDuring the delivery of effluent, Ca²⁺And HSO₄ ^-And a large amount of scaling substances such as acid salt, sulfur salt and the like are separated out, so that the conveying pipeline and surface equipment are often scaled and blocked.

In order to solve the problem that the produced water of the oil well blocks a conveying pipeline and ground equipment, people usually perform descaling treatment on the produced water of the oil well and then perform other treatments, wherein the existing descaling method is a descaling device and a descaling system disclosed as an authorized bulletin No. CN 103805228B; the invention patent with the publication number of CN209318373U discloses a cooling tower filler descaling device; the scale remover is added into the produced water of the oil well, so that the scale remover and ions which are easy to scale in the produced water of the oil well are subjected to chemical reaction to generate precipitates, and then the precipitates are separated to achieve the purpose of removing the scale. However, the chemical reaction of the scale remover and the ions in the produced water of the oil well to generate the precipitate is a reversible reaction, namely, after the scale remover and the ions in the produced water of the oil well react to generate the precipitate, the precipitate can also react reversely to be dissolved again. Therefore, the problem of poor descaling effect exists when the existing descaling equipment, namely the descaling mode, is adopted to treat the produced water of the oil well. In addition, the existing descaling equipment has the problem that the filter plates are not enough in arrangement, so that the working efficiency is low, and the requirement of enterprises on descaling the produced water of the oil well cannot be met.

Disclosure of Invention

The invention aims to: the structure is compact and the design is ingenious; the method solves the problems of poor descaling effect and low working efficiency of the existing method for descaling the oil well produced water.

The technical scheme of the invention is as follows:

a descaling method for oil well produced water is characterized in that: the descaling method for the oil well produced water comprises the following steps:

1. na in the produced water of the oil well is measured according to the national standard SY/T5523-2016 oil-gas field water analysis method⁺、HSO4^-、Ca²⁺And Cl^-The concentration of (c); if the produced water of the oil well detects Na⁺Concentration ratio of (C) Ca²⁺Is two orders of magnitude higher, andHSO4^-concentration ratio of ions Cl^-If the concentration of the sodium sulfate is two orders of magnitude higher, the produced water of the oil well is sodium bisulfate;

if the oil well produced water detects Ca²⁺Concentration ratio of (A) to (B) of (B)⁺Is two orders of magnitude higher, and Cl^-Concentration ratio of ions HSO4^-If the concentration of the water is two orders of magnitude higher, the produced water of the oil well is of a calcium chloride type;

if the oil well produced water detects Ca²⁺Concentration of (A) and Na⁺Has a concentration difference of less than two orders of magnitude and is Cl^-Concentration of ions and HSO4^-The concentration difference of the water is less than two orders of magnitude, and the produced water of the oil well is mixed;

2.1 if the produced water of the oil well is of a sodium bisulfate type, the descaling mode of the produced water of the sodium bisulfate type oil well is as follows:

(1) switching an inlet end of a chemical supply pump in the descaling device for the produced water of the oil well to be communicated with a barium chloride aqueous solution chemical supply system; the concentration of the aqueous barium chloride solution is C₂，C₂The concentration range of (A) is 208-312 g/L; setting the NaHSO in the oil well produced water measured in the step 1₄At a concentration of C₁(ii) a The flow rate of the liquid supply pump is V1, and the flow rate of the medicine supply pump is V₂(ii) a BaCl is known₂Has a relative molecular mass of 208 and a relative molecular mass of NaHSO4 of 120; BaCl₂The reaction equation with NaHSO4 is as follows:

(2) after the calculation of the processes is finished, communicating the inlet end of a liquid supply pump in the oil well produced water descaling device with external clean water, then opening a liquid inlet valve and an exhaust valve, starting the liquid supply pump to enable the liquid supply pump to input the clean water into the filter tank, and closing the exhaust valve when the filter tank is filled with the clean water and the clean water is discharged from an exhaust elbow; the exhaust function is to exhaust the air in the tank, detect whether the whole device is safe, and have the function of protecting the pump;

(3) after the gas in the filtering tank is discharged, the liquid feeding pump is driven inThe port end is communicated with the produced water of the oil well; opening a liquid outlet valve and an isolation valve of a descaling device for oil well produced water; then starting a liquid supply pump and a medicine supply pump; make the liquid supply pump at V₂The produced water of the oil well is input into the filter tank through the liquid inlet pipe; make the medicine supply pump at V₂Pumping the barium chloride aqueous solution into a filtering tank at the flow rate; then starting a pressure pump, after the pressure pump is started, filtering mixed liquid of water produced by an oil well in a filter tank and a barium chloride aqueous solution by a filter cylinder, then entering the pressure pump after passing through a filter disc, a water outlet branch pipe, a water outlet valve and a main collecting pipe, pressurizing by the pressure pump, and discharging the filtered mixed liquid through an isolation valve and a liquid outlet pipe; fully mixing the produced water with a barium chloride aqueous solution in the process that the produced water of the oil well enters the filtering tank; BaCl in aqueous barium chloride solution₂Reacting with NaHSO4 in the produced water of the oil well to generate sediment BaSO 4; after the precipitate is generated, one part of the precipitate sinks to the bottom of the filter tank under the action of gravity, and one part of the precipitate gradually moves upwards along with the mixed liquid, and the mixed liquid is attached to the surface of the filter tank after being filtered by the filter cylinder in the upward movement process of the mixed liquid; HSO4 in the produced water of such a well^-The water is precipitated in a BaSO4 form under the action of a barium chloride aqueous solution, so that the aim of descaling the produced water of the sodium bisulfate type oil well is fulfilled;

2.2 if the produced water of the oil well is of a calcium chloride type, the scale removal mode of the produced water of the calcium chloride type oil well is as follows:

(1) switching the inlet end of the chemical supply pump of the oil well produced water descaling device to NaHCO₃The solution medicament supply system is communicated; NaHCO 2₃The concentration of the solution agent is C₃；C₃The concentration range of (A) is 0.3-0.6 g/L; setting NaHCO in the oil well produced water measured in the step 1₃At a concentration of C₄(ii) a The flow rate of the liquid supply pump is V3, and the flow rate of the medicine supply pump is V₄(ii) a Known as CaCl₂Has a relative molecular mass of 111, NaHCO₃Has a relative molecular mass of 84; CaCl₂With NaHCO₃The reaction equation is as follows:

(2) after the calculation of the processes is finished, communicating the inlet end of a liquid supply pump of the descaling device for oil well produced water with external clean water, then opening a liquid inlet valve and an exhaust valve, starting the liquid supply pump to enable the liquid supply pump to input clean water into the interior of the filter tank, and closing the exhaust valve when the interior of the filter tank is filled with clean water and clean water is discharged from an exhaust elbow; the exhaust function is to exhaust the air in the tank, detect whether the whole device is safe, and have the function of protecting the pump;

(3) after the gas in the filter tank is discharged, communicating the inlet end of the liquid supply pump with the produced water of the oil well; opening the liquid outlet valve and the isolation valve; then starting a liquid supply pump and a medicine supply pump; enabling a liquid supply pump to input the oil well produced water into a filtering tank through a liquid inlet pipe at the flow rate of V3; make the medicine supply pump at V₄Flux of NaHCO₃Pumping the solution into a filtering tank; then starting a pressure pump, and after the pressure pump is started, extracting water and NaHCO from an oil well in a filter tank₃After being filtered by a filter cartridge, the mixed liquid of the solution enters a pressure pump after passing through a filter disc, a water outlet branch pipe, a liquid outlet valve and a main collecting pipe, is pressurized by the pressure pump, and is discharged outside through an isolation valve and the liquid outlet pipe; the produced water of the oil well is mixed with NaHCO in the process of entering the filtering tank₃Mixing the solution thoroughly, NaHCO₃CaCl in solution and oil well produced water₂Reaction to form precipitated CaCO₃(ii) a In the process, the NaOH solution is pumped into the filtering tank by an alkali supply pump; NaOH solution concentration of C₅，C₅The concentration range of (A) is 4-40 g/L; the NaOH solution is input into the filtering tank to achieve the purpose of adjusting the PH value in the filtering tank; then, the PH value of the mixed liquor at the bottom of the tank in the filter tank is kept by observing the reading of a PH test sensor and regulating the flow of an alkali supply pump; in addition, the descaling heater is required to be turned on simultaneously, so that the temperature of the mixed liquid in the filter tank is kept at 70 ℃; after the precipitate is generated, one part of the precipitate sinks to the bottom of the filter tank under the action of gravity, and one part of the precipitate gradually moves upwards along with the mixed liquid, and the mixed liquid is attached to the surface of the filter tank after being filtered by the filter cylinder in the upward movement process of the mixed liquid; ca in the produced water of such oil well²⁺Will be in NaHCO₃With the aid of CaCO₃The calcium chloride type oil well produced water is precipitated, so that the aim of descaling the calcium chloride type oil well produced water is fulfilled;

2.3 if the produced water of the oil well is mixed, two scale removal devices are required to be connected in series to remove Na respectively⁺、HSO4^-And Ca²⁺、Cl^-In the first descaling device, Na is removed first⁺、HSO4^-In a second descaling device to remove Ca again²⁺、Cl^-(ii) a The mixed oil well produced water descaling mode is as follows:

(1) in the first descaling device, the inlet end of a medicine supply pump is switched to be communicated with a barium chloride aqueous solution medicine supply system; the concentration of the aqueous barium chloride solution is C₂，C₂The concentration range of (A) is 208-312 g/L; the inlet end of the medicine supply pump in the second descaling device is switched to NaHCO₃The solution medicament supply system is communicated; NaHCO 2₃The concentration of the solution agent is C₃；C₃The concentration range of (A) is 0.3-0.6 g/L;

setting the concentration of NaHSO4 in the oil well produced water measured in the step 1 as C₁(ii) a The flow rate of the liquid supply pump in the first descaling device is V1, and the flow rate of the chemical supply pump is V₂(ii) a Setting NaHCO in the oil well produced water measured in the step 1₃At a concentration of C₄(ii) a The flow rate of the liquid supply pump in the second descaling device is set as V3, and the flow rate of the chemical supply pump is set as V₄(ii) a Known as CaCl₂Has a relative molecular mass of 111, NaHCO₃Has a relative molecular mass of 84; BaCl₂Has a relative molecular mass of 208 and a relative molecular mass of NaHSO4 of 120; BaCl₂Reaction equation with NaHSO4 and CaCl₂With NaHCO₃The reaction equation is as follows:

(2) after the calculation of the processes is finished, communicating the inlet end of the liquid supply pump with external clean water, then opening the liquid inlet valve and the exhaust valve, then starting the liquid supply pump, enabling the liquid supply pump to input the clean water into the filter tank, and closing the exhaust valve when the filter tank is filled with the clean water and the clean water is discharged from the exhaust elbow; the exhaust effect is the exhaust jar interior air, detects whether safe of whole device, and has the effect of protection pump.

(3) After the gas in the filter tanks of the first descaling device and the second descaling device is discharged, communicating the inlet end of the liquid supply pump of the first descaling device with the produced water of the oil well; the inlet end of the liquid supply pump of the second descaling device is communicated with the liquid outlet pipe of the first descaling device; then simultaneously opening a liquid outlet valve and an isolation valve in the first descaling device and the second descaling device; then starting a liquid supply pump and a chemical supply pump in the first descaling device and the second descaling device; a liquid supply pump in the first descaling device is enabled to be V₂The produced water of the oil well is input into the filter tank through the liquid inlet pipe; the chemical supply pump in the first descaling device is driven to be V₂Pumping the barium chloride aqueous solution into a filtering tank at the flow rate; then starting a pressurizing pump in the first descaling device; after the pressurizing pump is started, HSO4 in the first descaling device is completed^-The mixed liquid for descaling is conveyed into a second descaling device through a liquid outlet pipe; at the moment, a liquid supply pump in the second descaling device inputs the oil well produced water into a second descaling device filter tank through a liquid inlet pipe at the flow rate of V3; make the medicine supply pump at V₄Flux of NaHCO₃Pumping the solution into a filtering tank; then starting a pressure pump of the second descaling device, after the pressure pump is started, filtering mixed liquid in the filter tank by a filter cartridge, then entering the pressure pump after passing through a filter disc, a water outlet branch pipe, a liquid outlet valve and a main collecting pipe, pressurizing by the pressure pump, and then discharging the filtered mixed liquid out through an isolation valve and a liquid outlet pipe; in the process, the NaOH solution is pumped into the filtering tank by an alkali supply pump; NaOH solution concentration of C₅，C₅The concentration range of (A) is 4-40 g/L; the NaOH solution is input into the filtering tank to achieve the purpose of adjusting the PH value in the filtering tank; then, the PH value of the mixed liquor at the bottom of the tank in the filter tank is kept at 8 by observing the reading of a PH test sensor and adjusting the flow of an alkali supply pump; in addition, the descaling heater is required to be turned on simultaneously, so that the temperature of the mixed liquid in the filter tank is kept at 70 ℃; ca in the thus-mixed solution²⁺Will be in NaHCO₃With the aid of CaCO₃Shape ofThe scale is precipitated, thereby achieving the purpose of descaling the produced water of the mixed oil well.

The descaling device for the oil well produced water comprises a filter tank, a filter disc, a filter cartridge, a liquid supply pump, an alkali supply pump, a chemical supply pump, a booster pump and a main manifold; the bottom of the filter tank is connected with a liquid supply pump through a liquid inlet valve and a liquid inlet pipe; a plurality of filter discs are arranged in the filter tank at intervals in an up-down manner; the lower end surface of the filter disc is provided with a plurality of filter cartridges at regular intervals; one side of the filter disc is connected with a water outlet branch pipe; the water outlet branch pipe extends to the outer end of the filter tank and is communicated with the main collecting pipe through a water outlet valve; the lower end of the main collecting pipe is connected with a liquid outlet pipe through a pressurizing pump; the bottom of the filter tank is connected with an alkali supply pump through a pipeline, and is connected with a drug supply pump through a pipeline.

The filter disc is of a disc-shaped structure with a hollow inner part; the filter cartridge is composed of an inner framework, a filter fiber cartridge, an upper end cover and a lower end cover; the circumferential surface of the inner framework is provided with a filtering fiber cylinder by an upper end cover and a lower end cover which are connected by screw threads; the filter cartridge passes through upper end cover and filter disc threaded connection.

The bottom of the filter tank is provided with a descaling heater; the lower part of the filtering tank is provided with a temperature sensor and a PH test sensor.

The bottom of the filter tank is connected with a sewage pump through a pipeline; the outlet of the sewage pump is sequentially connected with an overflow layering box and a lifting pump; the outlet end of the lift pump is communicated with the liquid outlet pipe through a pipeline and a valve.

The overflow layering box consists of a layering box body, a partition plate and a water turning plate; a plurality of isolation plates are fixedly arranged in the layered box body at intervals; the layered box body is divided into a plurality of chambers by the partition boards; a distance is reserved between the upper end of the isolation plate and the edge of the layered box body; a water turning plate is arranged in the layered box body on one side of the isolation plate; the lower end of the water turning plate is spaced from the bottom plate of the layered box body by a certain distance; the upper end surface of the water turning plate is higher than the upper end of the isolation plate; the upper end of the right side of the layering box body is communicated with a sewage pump; the upper end of the left side of the layering box body is communicated with a lift pump; the partition board in the layered box body is gradually raised from left to right.

A purging main pipe is arranged in the filtering tank; a blowing branch pipe is arranged above the filter disc; a plurality of blowing nozzles are arranged on the blowing branch pipe; the purging branch pipes are communicated with the purging main pipe; the upper end of the blowing main pipe extends to the outer end of the filter tank and is communicated with the liquid outlet pipe through a flushing pipe and a valve; the liquid outlet pipes on two sides of the flushing pipe are respectively provided with an isolation valve.

The liquid outlet pipe of the outlet of the pressurizing pump is communicated with the bottom of the filter tank through a safety detection pipe and a valve; the water outlet branch pipe is provided with a differential pressure sensor; one probe of the differential pressure sensor is communicated with the corresponding water outlet branch pipe, and the other probe is communicated with the filter tank.

The upper end of the filter tank is provided with an exhaust elbow through an exhaust valve.

One side of the filter tank is provided with a gas storage tank; the gas storage tank is communicated with the main collecting pipe through a pipeline and a back flushing valve.

The invention has the advantages that:

the descaling method for the oil well produced water has compact structure and smart design; the yield of the existing descaling device is improved by arranging the filter disc and the filter cylinder in the filter tank; the precipitate is inhibited from being redissolved by adjusting the pH value and controlling the temperature, so that the descaling effect is improved; therefore, the problems of poor descaling effect and low descaling efficiency of the existing descaling device are solved, and the requirement of enterprises on the descaling of the produced water of the oil well is met.

Description of the drawings:

FIG. 1 is a schematic structural view of a descaling device according to the present invention;

FIG. 2 is a schematic view of the construction of a canister according to the present invention;

FIG. 3 is a schematic view of a cartridge construction of the present invention;

FIG. 4 is a schematic top view of the descaling device of the present invention;

FIG. 5 is a schematic view of the structure of FIG. 2 in the direction A-A;

fig. 6 is a side view schematically showing the construction of the canister of the present invention.

In the figure: 1. the device comprises a filter tank, 2, a filter disc, 3, a filter cartridge, 4, a liquid supply pump, 5, an alkali supply pump, 6, a medicine supply pump, 7, a pressure pump, 8, a liquid inlet valve, 9, a liquid inlet pipe, 10, a water outlet branch pipe, 11, a liquid outlet valve, 12, a main collecting pipe, 13, a liquid outlet pipe, 14, a descaling heater, 15, an inner framework, 16, a filter fiber cartridge, 17, an upper end cover, 18, a lower end cover, 19, an exhaust elbow, 20, an exhaust valve, 21, a gas storage tank, 22, a sewage pump, 23, an overflow layering box, 24, a lifting pump, 25, a layering box body, 26, an isolation plate, 27, a water turning plate, 28, a blowing branch pipe, 29, a blowing nozzle, 30, a blowing main pipe, 31, a flushing pipe, 32, an isolation valve, 33, a safety detection pipe, 34 and a differential pressure sensor.

Detailed Description

The descaling method of the oil well produced water comprises a filter tank 1, a filter disc 2, a filter cylinder 3, a liquid supply pump 4, an alkali supply pump 5, a chemical supply pump 6, a booster pump 7 and a main collecting pipe 12 (see the attached figure 1 of the specification).

The bottom of the filter tank 1 is connected with a liquid supply pump 4 through a liquid inlet valve 8 and a liquid inlet pipe 9; the liquid supply pump 4 is communicated with an external oil well produced water storage tank; when the liquid supply pump 4 works, the produced water of the oil well can be input into the filter tank 1 through the liquid inlet valve 8 and the liquid inlet pipe 9.

A plurality of filter discs 2 are arranged in the filter tank 1 at intervals in an up-down manner (see the attached figure 2 in the specification); the filter disc 2 is of a hollow disc-shaped structure; a certain gap is reserved between the periphery of the filter disc 2 and the inner wall of the filter tank 1 (see the attached figure 5 in the specification); after the produced water of the oil well enters the filter tank 1 from the bottom, the produced water can move upwards through the gap between the filter disc 2 and the filter tank 1 until the filter tank 1 is filled.

A plurality of filter cartridges 3 are arranged on the lower end surface of the filter disc 2 at regular intervals (see the attached figure 2 in the specification); the filter cartridge 3 is composed of an inner framework 15, a filter fiber cartridge 16, an upper end cover 17 and a lower end cover 18; the circumferential surface of the inner framework 15 is provided with a filtering fiber cylinder 16 through an upper end cover 17 and a lower end cover 18 which are connected by screw threads; the filter cartridge 3 is screwed with the filter disc 2 through the upper end cover 17 (refer to the attached figure 3 in the specification). During operation, the produced water of the oil well can pass through the filtering fiber cylinder 16 and then enter the inside of the filtering disc 2, and in the process, the filtering fiber cylinder 16 filters the produced water of the oil well and separates dirt from the outside of the filtering cylinder 3; the filtered oil well produced water is discharged through the water outlet branch pipe 10.

One side of the filter disc 2 is connected with a water outlet branch pipe 10 (see the description and the attached figure 2); the water outlet branch pipe 10 extends to the outer end of the filter tank 1 and is communicated with a main collecting pipe 12 through a water outlet valve 11; the lower end of the main collecting pipe 12 is connected with a liquid outlet pipe 13 through a pressurizing pump 7 (see the attached figure 1 in the specification). During working, the oil well produced water after being filtered enters a main collecting pipe 12 through a water outlet branch pipe 10, is finally pressurized by a pressurizing pump 7 and then is discharged outside through a liquid outlet pipe 13.

The bottom of the filter tank 1 is connected with an alkali supply pump 5 through a pipeline; a medicine supply pump 6 (see the attached figure 1 of the specification) is connected through a pipeline. When the alkali supply pump 5 works, the external alkali liquor can be conveyed into the filter tank 1 for adjusting the pH value in the filter tank 1.

The bottom of the filter tank 1 is provided with a descaling heater 14 (see the attached figure 1 in the specification); the descaling heater 14 can heat the liquid in the filter tank 1 when in operation. The descaling heater 14 is a market purchasing device, has the characteristics of large heating area, high heating speed, high heating efficiency and suitability for fast flowing liquid, can stabilize the liquid in the filter tank 1 to a certain specified temperature when the descaling heater 14 works, and further achieves the purpose of inhibiting the precipitation from being decomposed again by means of adjusting the temperature in the filter tank 1.

The lower part of the filter tank 1 is provided with a temperature sensor and a PH test sensor. The temperature sensor and the PH test sensor can respectively monitor the temperature and the PH value of the liquid in the filter tank 1; during operation people can adjust the temperature and the PH value of the liquid in the filtering tank 1 according to the monitoring values of the temperature and the PH value.

The bottom of the filter tank 1 is connected with a sewage pump 22 through a pipeline; the outlet of the sewage pump 22 is connected with an overflow layering box 23 and a lifting pump 24 in sequence; the outlet end of lift pump 24 is connected to outlet pipe 13 via a pipe and a valve (see fig. 1). When the sewage pump 22 works, the sediment at the bottom of the filter tank 1 can be pumped out along with the cleaning water, and after the sediment is layered by the overflow layering box 23, the processed oil well produced water is discharged outside through the lifting pump 24 and the liquid outlet pipe 13.

The overflow layering box 23 is composed of a layering box body 25, a partition plate 26 and a water turning plate 27 (see the description and the attached figure 1); a plurality of partition plates 26 are fixedly arranged in the layered box body 25 at intervals; the partition plate 26 divides the layered tank 25 into a plurality of chambers; a distance exists between the upper end of the isolation plate 26 and the edge opening of the layered box body 25; a water turning plate 27 is arranged in the layered box body 25 on one side of the isolation plate 26; the lower end of the water turning plate 27 is at a certain distance from the bottom plate of the layered box body 25; the upper end face position of the water turn-over plate 27 is higher than the upper end position of the partition plate 26.

The upper end of the right side of the layering box body 25 is communicated with the sewage pump 22; the upper end of the left side of the layering box body 25 is communicated with the lift pump 24; the partition plate 26 inside the layered casing 25 is raised stepwise from left to right. After the overflow layering box 23 is arranged in this way, after the oil well produced water with sediments enters the layering box body 25, the oil well produced water enters between the partition plate 26 and the water turning plate 27 from the lower part of the water turning plate 27 and finally overflows to the next cavity through the upper end of the partition plate 26; in the process, the sediment is easy to sink due to high density, so that the produced water of the oil well is gradually separated from the sediment, the produced water of the oil well is thoroughly separated from the sediment after passing through the plurality of water turning plates 27 and the isolation plates 26, and finally the separated produced water of the oil well is conveyed to the liquid outlet pipe 13 through a pipeline by the lifting pump 24 to be discharged.

After the descaling device works for a period of time and when the sediment at the bottom of the filter tank 1 needs to be cleaned, the sewage pump 22 and the lift pump 24 are directly started to convey the sediment at the bottom of the filter tank 1 and the mixed liquid to the layering box 25, and the sediment is separated under the action of the water turning plate 27 and the isolation plate 26, so that the mixed liquid is conveyed to the liquid outlet pipe 13 through the lift pump 24 to be discharged.

The interior of the filter tank 1 is provided with a purging header pipe 30 (see the description and the attached figure 2); a blowing branch pipe 28 is arranged above the filter disc 2; a plurality of purging nozzles 29 are arranged on the purging branch pipe 28; the purge branch 28 communicates with a purge manifold 30 (see FIG. 2).

The upper end of the purging main pipe 30 extends to the outer end of the filter tank 1 and then is communicated with the liquid outlet pipe 13 through a flushing pipe 31 and a valve (see the attached figure 1 in the specification); the liquid outlet pipes 13 on both sides of the flushing pipe 31 are respectively provided with an isolation valve 32 (refer to the attached figure 1 in the specification). The purpose of so positioning the purge manifold 30 and the purge branch 28 is to: after the descaling device works for a period of time, when a lot of sediments deposited on the upper surface of the filter disc 2 need to be cleaned, the liquid outlet pipe 13 can be communicated with an external cleaning water system, and a valve on the flushing pipe 31 is opened, so that cleaning water with certain pressure can enter the purging branch pipe 28 through the liquid outlet pipe 13, the flushing pipe 31 and the purging main pipe 30, and finally is sprayed out through the purging spray head 29 on the purging branch pipe 28, so that the purpose of cleaning the upper surface of the filter disc 2 is achieved.

The upper end of the filter tank 1 is provided with a vent elbow 19 through a vent valve 20 (see the attached figure 1 in the specification). In the earlier stage of the descaling device, the exhaust valve 20 can be opened, so that the gas in the filter tank 1 can be discharged outside through the exhaust elbow 19; after the gas is discharged out, the exhaust valve 20 is closed, and the descaling device can enter a normal working mode.

The liquid outlet pipe 13 at the outlet of the pressure pump 7 is communicated with the bottom of the filter tank 1 through a safety detection pipe 33 and a valve (see the attached figure 1 in the specification); a differential pressure sensor 34 is arranged on the water outlet branch pipe 10; one probe of the differential pressure sensor 34 is communicated with the corresponding water outlet branch pipe 10, and the other probe is communicated with the filter tank 1 (see the figure 6 in the specification). The differential pressure sensor 34 can detect the differential pressure between the outlet branch pipe 10 and the filter tank 1.

The safety detecting tube 33 and the differential pressure sensor 34 are thus provided for the purpose of: firstly, the pressure difference between the water outlet branch pipe 10 and the filter tank 1 can be monitored through the pressure difference sensor 34 during working, and whether the descaling device is in a normal operation state is judged by judging whether the pressure difference is in a qualified range. Then the liquid outlet valve 11 and the valves on the safety detection pipe 33 can be opened to close other valves, and then the booster pump 7 is started to enable the liquid in the filter tank 1 to circularly flow among the filter tank 1, the booster pump 7 and the safety detection pipe 33; therefore, people can monitor the descaling device to see whether the descaling device can normally operate or not; and whether the filter cartridge 3 needs to be cleaned or replaced can be judged by observing the value of the differential pressure sensor 34.

One side of the filter tank 1 is provided with a gas storage tank 21; the air reservoir 21 communicates with the main manifold 12 via a conduit and a blow-back valve 22 (see figure 1 of the specification). The purpose of providing the air tank 21 is: after the descaling device works for a period of time, when the working efficiency of the descaling device is reduced due to too much scale accumulated on the filter cartridge 3, the descaling device can be closed, the blowback valve 22, the liquid outlet valve 11 and the exhaust valve 20 are opened to close other valves, so that the gas in the gas storage tank 21 enters the interior of the filter disc 2 through the main collecting pipe 12 and the water outlet branch pipe 10 with certain pressure, finally passes through the filter cartridge 3 from the interior and is discharged outside. Thus, the purpose of cleaning the filter cartridge 3 through a back flushing mode can be achieved.

The descaling method for the oil well produced water comprises the following working processes:

1. na in the produced water of the oil well is measured according to the national standard SY/T5523-2016 oil-gas field water analysis method⁺、HSO4^-、Ca²⁺And Cl^-The concentration of (c); if the produced water of the oil well detects Na⁺Concentration ratio of (C) Ca²⁺Is two orders of magnitude higher, and HSO4^-Concentration ratio of ions Cl^-If the concentration of the sodium sulfate is two orders of magnitude higher, the produced water of the oil well is sodium bisulfate;

(1) the inlet end of the medicine supply pump 6 is switched to be communicated with a barium chloride aqueous solution medicine supply system; the concentration of the aqueous barium chloride solution is C₂，C₂In the concentration range ofIs 208 to 312 g/L; setting the NaHSO in the oil well produced water measured in the step 1₄At a concentration of C₁(ii) a The flow rate of the liquid supply pump 4 is V1, and the flow rate of the medicine supply pump 6 is V₂(ii) a BaCl is known₂Has a relative molecular mass of 208 and a relative molecular mass of NaHSO4 of 120; BaCl₂The reaction equation with NaHSO4 is as follows:

(2) after the above processes are calculated, the inlet end of the liquid supply pump 4 is communicated with external clean water, then the liquid inlet valve 8 and the exhaust valve 20 are opened, then the liquid supply pump 4 is started, so that the liquid supply pump 4 inputs clean water into the filter tank 1, and when the filter tank 1 is filled with clean water and clean water is blown out from the exhaust elbow 19, the exhaust valve 20 is closed; the exhaust effect is the exhaust jar interior air, detects whether safe of whole device, and has the effect of protection pump.

(3) After the gas in the filter tank 1 is discharged, the inlet end of the liquid supply pump 4 is communicated with the produced water of the oil well; opening the liquid outlet valve 11 and the isolation valve 32; then starting the liquid supply pump 4 and the medicine supply pump 6; the liquid supply pump 4 is set to V₂The produced water of the oil well is input into the filter tank 1 through the liquid inlet pipe 9; the medicine supply pump 6 is set at V₂Pumping the barium chloride aqueous solution into the filter tank 1 at the flow rate; then the pressure pump 7 is started, after the pressure pump 7 is started, mixed liquid of water produced by an oil well in the filter tank 1 and a barium chloride aqueous solution is filtered by the filter cylinder 3, enters the pressure pump 7 after passing through the filter disc 2, the water outlet branch pipe 10, the liquid outlet valve 11 and the main collecting pipe 12, is pressurized by the pressure pump 7, and is discharged through the isolation valve 32 and the liquid outlet pipe 13; fully mixing the produced water with a barium chloride aqueous solution in the process that the produced water of the oil well enters the filter tank 1; BaCl in aqueous barium chloride solution₂Reacting with NaHSO4 in the produced water of the oil well to generate sediment BaSO 4; after the precipitate is generated, one part of the precipitate sinks to the bottom of the filter tank 1 under the action of gravity, and the other part of the precipitate gradually moves upwards along with the mixed liquid, and the mixed liquid is attached to the surface of the filter tank after being filtered by the filter cylinder 3 in the upward movement process of the mixed liquid; HSO4 in the produced water of such a well^-The water is precipitated in a BaSO4 form under the action of a barium chloride aqueous solution, so that the aim of descaling the produced water of the sodium bisulfate type oil well is fulfilled;

(1) the inlet end of the medicine supply pump 6 is switched to be communicated with NaHCO₃The solution medicament supply system is communicated; NaHCO 2₃The concentration of the solution agent is C₃；C₃The concentration range of (A) is 0.3-0.6 g/L; setting NaHCO in the oil well produced water measured in the step 1₃At a concentration of C₄(ii) a The flow rate of the liquid feed pump 4 is V3, and the flow rate of the drug feed pump 6 is V₄(ii) a Known as CaCl₂Has a relative molecular mass of 111, NaHCO₃Has a relative molecular mass of 84; CaCl₂With NaHCO₃The reaction equation is as follows:

(3) After the gas in the filter tank 1 is discharged, the inlet end of the liquid supply pump 4 is communicated with the produced water of the oil well; opening the liquid outlet valve 11 and the isolation valve 32; then starting the liquid supply pump 4 and the medicine supply pump 6; the liquid supply pump 4 inputs the oil well produced water into the filter tank 1 through the liquid inlet pipe 9 at the flow rate of V3; the medicine supply pump 6 is set at V₄Flux of NaHCO₃Pumping the solution into a filter tank 1; then the pressure pump 7 is started, after the pressure pump 7 is started, water and NaHCO are produced from the oil well in the filter tank 1₃The mixed liquid of the solution is filtered by the filter cartridge 3, enters the pressure pump 7 after passing through the filter disc 2, the water outlet branch pipe 10, the liquid outlet valve 11 and the main collecting pipe 12, and is added by the pressure pump 7After the pressure is pressed, the mixed liquid after being filtered is discharged outside through an isolation valve 32 and a liquid outlet pipe 13; in the process that the produced water of the oil well enters the filter tank 1, the produced water of the oil well is mixed with NaHCO₃Mixing the solution thoroughly, NaHCO₃CaCl in solution and oil well produced water₂Reaction to form precipitated CaCO₃(ii) a In the process, NaOH solution is pumped into the filter tank 1 through an alkali supply pump 5; NaOH solution concentration of C₅，C₅The concentration range of (A) is 4-40 g/L; the NaOH solution is input into the filter tank 1 to achieve the purpose of adjusting the PH value in the filter tank 1; then, the PH value of the mixed liquor at the bottom of the tank in the filter tank 1 is kept at 8 by observing the reading of a PH test sensor and adjusting the flow of an alkali supply pump 5; besides, the descaling heater 14 is turned on simultaneously, so that the temperature of the mixed liquid in the filter tank 1 is kept at 70 ℃; after the precipitate is generated, one part of the precipitate sinks to the bottom of the filter tank 1 under the action of gravity, and the other part of the precipitate gradually moves upwards along with the mixed liquid, and the mixed liquid is attached to the surface of the filter tank after being filtered by the filter cylinder 3 in the upward movement process of the mixed liquid; ca in the produced water of such oil well²⁺Will be in NaHCO₃With the aid of CaCO₃The calcium chloride type oil well produced water is precipitated, so that the aim of descaling the calcium chloride type oil well produced water is fulfilled;

(1) in the first descaling device, the inlet end of a medicine supply pump 6 is switched to be communicated with a barium chloride aqueous solution medicine supply system; the concentration of the aqueous barium chloride solution is C₂，C₂The concentration range of (A) is 208-312 g/L; in the second descaling device, the inlet end of the drug supply pump 6 is switched to NaHCO₃The solution medicament supply system is communicated; NaHCO 2₃The concentration of the solution agent is C₃；C₃The concentration range of (A) is 0.3-0.6 g/L;

setting the concentration of NaHSO4 in the oil well produced water measured in step 1Is C₁(ii) a The flow rate of the liquid supply pump 4 in the first scale removing device is V1, and the flow rate of the chemical supply pump 6 is V₂(ii) a Setting NaHCO in the oil well produced water measured in the step 1₃At a concentration of C₄(ii) a Let the flow rate of the liquid feed pump 4 in the second scale removing device be V3 and the flow rate of the chemical feed pump 6 be V₄(ii) a Known as CaCl₂Has a relative molecular mass of 111, NaHCO₃Has a relative molecular mass of 84; BaCl₂Has a relative molecular mass of 208 and a relative molecular mass of NaHSO4 of 120; BaCl₂Reaction equation with NaHSO4 and CaCl₂With NaHCO₃The reaction equation is as follows:

(3) After the gas in the filter tanks 1 of the first descaling device and the second descaling device is discharged, the inlet end of a liquid feed pump 4 of the first descaling device is communicated with the produced water of the oil well; the inlet end of the liquid supply pump 4 of the second descaling device is communicated with the liquid outlet pipe 13 of the first descaling device; then simultaneously opening the liquid outlet valve 11 and the isolation valve 32 in the first descaling device and the second descaling device; then starting a liquid supply pump 4 and a chemical supply pump 6 in the first descaling device and the second descaling device; the liquid supply pump 4 in the first descaling device is set to V₂The produced water of the oil well is input into the filter tank 1 through the liquid inlet pipe 9; the chemical supply pump 6 in the first descaling device is set to be V₂Pumping the barium chloride aqueous solution into the filter tank 1 at the flow rate; then the booster pump 7 in the first descaling device is started; after the pressurizing pump 7 is started, HSO4 in the first descaling device is completed^-The mixed liquid for descaling is conveyed into a second descaling device through a liquid outlet pipe 13; at this time in the second descaling deviceThe liquid pump 4 inputs the produced water of the oil well into the filter tank 1 of the second descaling device through the liquid inlet pipe 9 at the flow rate of V3; the medicine supply pump 6 is set at V₄Flux of NaHCO₃Pumping the solution into a filter tank 1; then a pressure pump 7 of the second descaling device is started, after the pressure pump 7 is started, mixed liquid in the filter tank 1 is filtered by the filter cylinder 3, then enters the pressure pump 7 after passing through the filter disc 2, the water outlet branch pipe 10, the liquid outlet valve 11 and the main collecting pipe 12, is pressurized by the pressure pump 7, and then is discharged through the isolation valve 32 and the liquid outlet pipe 13; in the process, NaOH solution is pumped into the filter tank 1 through an alkali supply pump 5; NaOH solution concentration of C₅，C₅The concentration range of (A) is 4-40 g/L; the NaOH solution is input into the filter tank 1 to achieve the purpose of adjusting the PH value in the filter tank 1; then, the PH value of the mixed liquor at the bottom of the tank in the filter tank 1 is kept at 8 by observing the reading of a PH test sensor and adjusting the flow of an alkali supply pump 5; besides, the descaling heater 14 is turned on simultaneously, so that the temperature of the mixed liquid in the filter tank 1 is kept at 70 ℃; ca in the thus-mixed solution²⁺Will be in NaHCO₃With the aid of CaCO₃The scale is precipitated, thereby achieving the purpose of descaling the mixed oil well produced water.

In order to prove that the precipitate can be effectively inhibited from being redissolved and the advanced descaling effect can be improved by adjusting the pH value and controlling the temperature, the applicant respectively carries out the following tests on the oil well produced water in sodium bisulfate water type and calcium chloride water type.

The test procedure for the sodium bisulfate water type oil well produced water was as follows:

test materials: sodium bisulfate water type oil well produced water, Na thereof⁺And HSO4^-In an amount of

A barium chloride aqueous solution medicament with the concentration of 1mol/L, an astronomical temperature controller, a thermometer, a beaker, a measuring cup, a glass rod, a PH meter, an electronic balance and filter paper.

The test process with the variable as temperature is as follows:

1. measuring 1000ml of sodium bisulfate water type oil well produced water by using a beaker, adding 64ml of barium chloride aqueous solution medicament into the beaker, and uniformly stirring by using a glass rod; gradually generating precipitate in the stirring process; then placing the beaker in a temperature controller, adjusting the temperature controller to keep the temperature at 25 ℃, and taking out the beaker after 24 hours; and then filtering out the precipitate by using filter paper, standing for 2 hours, weighing the precipitate by using a balance, and recording the weighing result.

2. Repeating the test method in step 1 for 15 times, placing the beaker in a temperature controller, adjusting the temperature controller to maintain the temperature at 30 deg.C, 35 deg.C, 40 deg.C, 45 deg.C, 50 deg.C, 55 deg.C, 60 deg.C, 65 deg.C, 70 deg.C, 75 deg.C, 80 deg.C, 85 deg.C, 90 deg.C, 95 deg.C and 100 deg.C, and taking out the beaker after 24 hr; and then filtering out the precipitate by using filter paper, standing for 2 hours, weighing the precipitate by using a balance, and recording the weighing result.

And (3) test results: the results of the precipitate test are as follows:

as can be seen from the above test results, BaSO was observed in the range of 25 ℃ to 100 ℃ as the temperature increased₄The formation amount of precipitate and scale is continuously reduced, and at the temperature of 25 ℃, BaSO is added₄The generation amount of precipitated scale is 2012mg/L, and when the temperature is increased to 100 ℃, BaSO₄The amount of the generated precipitate and scale is reduced to 531mg/L, so that when the water type of the produced water of the oil well is sodium bisulfate, the normal temperature can ensure higher scale removal efficiency.

Secondly, the test process when the variable is the pH value is as follows:

1. measuring 1000ml of sodium bisulfate water type oil well produced water by using a beaker, adding 64ml of barium chloride aqueous solution medicament into the beaker, and uniformly stirring by using a glass rod; gradually generating precipitate in the stirring process; then gradually adding sodium hydroxide with the concentration of 0.1mol/L into the beaker, and continuously stirring the sodium hydroxide; in the process, a pH meter is used for measuring the pH value, and when the pH value in the beaker is 6, the addition of the sodium hydroxide is stopped and the stirring is stopped; standing for 2h, filtering out the precipitate by using filter paper, standing for 2h, weighing the precipitate by using a balance, and recording the weighing result.

2. The test method according to step 1 was repeated 6 times so that the pH in the beaker was 6.5, 7, 7.5, 8, 8.5 and 9 respectively to weigh the precipitate formed in the beaker and record the weighing result.

And (3) test results: the results of the precipitate test are as follows:

as can be seen from the above test results, BaSO was measured at a pH of 6₄The amount of scale formed by precipitation was 1996mg/L, and when the pH was 9, BaSO was added₄The amount of scale formation by precipitation was 2011mg/L, from which it was found that BaSO was produced depending on the pH₄The amount of precipitate and scale formation is less varied, so that the pH value is adjusted to BaSO₄The influence of the amount of the generated sediment and scale is small, so when the produced water of the oil well is in a sodium bisulfate type, the PH value is not adjusted.

The test procedure for calcium chloride water type oil well produced water was as follows:

test materials: calcium chloride water type oil well produced water, Ca thereof²⁺And Cl^-In an amount of

NaHCO3 solution with concentration of 0.37g/L, a space electric temperature controller, a thermometer, a beaker, a measuring cup, a glass rod, a PH meter, an electronic balance and filter paper.

The test process with the variable as temperature is as follows:

1. measuring 1000ml of calcium chloride water type oil well produced water by using a beaker, adding 157ml of NaHCO3 solution agent into the beaker, and uniformly stirring by using a glass rod; gradually generating precipitate in the stirring process; then placing the beaker in a temperature controller, adjusting the temperature controller to keep the temperature at 25 ℃, and taking out the beaker after 24 hours; and then filtering out the precipitate by using filter paper, standing for 2 hours, weighing the precipitate by using a balance, and recording the weighing result.

And (3) test results: the results of the precipitate test are as follows:

as can be seen from the above test results, CaCO was used in the range of 25 ℃ to 70 ℃₃The generation amount of the precipitated scale is increased from 526mg/L to 1678mg/L, and CaCO is added when the temperature is increased from 70 ℃ to 100 DEG C₃The formation amount of the deposited scale is increased to 1721mg/L from 1678mg/L only and CaCO is between 70 and 100 DEG C₃The amount of precipitated scale formation is already substantially unchanged with increasing temperature, so that a temperature of 70 ℃ ensures a higher descaling efficiency.

Secondly, the test process when the variable is the pH value is as follows:

as can be seen from the above test results, CaCO was used when the pH of the produced water was adjusted from 6 to 8₃The generation amount of the precipitated scale is increased from 658mg/L to 1565mg/L, and CaCO is added when the pH value of the produced water is adjusted from 8 to 10₃The amount of the precipitated scale formation is increased from 1565mg/L to 1603mg/L, so that CaCO can be obtained after the pH value is more than 8₃The amount of the precipitated scale formation does not substantially change with the increase of the pH value, so that a pH value of 8 ensures high scale removal efficiency.

To illustrate (typical case):

1. na of the produced water of a B well oil well can be measured according to the national standard SY/T5523-2016 oil-gas field water analysis method⁺At a concentration of

HSO4^-At a concentration of

Ca²⁺At a concentration of

Cl^-At a concentration of

At a concentration of NaHSO4 of

Due to Na⁺Concentration ratio of (C) Ca²⁺Is higher than two orders of magnitude, and HSO4^-Concentration ratio of ions Cl^-Is higher than two orders of magnitude, the produced water of the oil well is sodium bisulfate type. The scale removal mode of the produced water of a certain B well oil well is as follows:

(1) the inlet end of the medicine supply pump 6 is switched to be communicated with a barium chloride aqueous solution medicine supply system; concentration C of barium chloride aqueous solution₂Is 208 g/L; measured NaHSO in the produced water of an oil well₄At a concentration of

(ii) a The flow rate of the known feed pump 4 is 10⁵L/h，BaCl₂Has a relative molecular mass of 208 and a relative molecular mass of NaHSO4 of 120; the flow rate of the medicine supply pump 6 is set to be V₂L/h, BaCl is known₂The reaction equation with NaHSO4 is as follows:

(3) After the gas in the filter tank 1 is discharged, the inlet end of the liquid supply pump 4 is communicated with the produced water of the oil well; opening the liquid outlet valve 11 and the isolation valve 32; then starting the liquid supply pump 4 and the medicine supply pump 6; the liquid supply pump 4 is set at 10⁵The produced water of the oil well is input into the filter tank 1 through the liquid inlet pipe 9 at the flow rate of L/h; pumping barium chloride aqueous solution into the filter tank 1 by a drug supply pump 6 at the flow rate of 6394L/h; then the pressure pump 7 is started, after the pressure pump 7 is started, mixed liquid of water produced by an oil well in the filter tank 1 and a barium chloride aqueous solution is filtered by the filter cylinder 3, enters the pressure pump 7 after passing through the filter disc 2, the water outlet branch pipe 10, the liquid outlet valve 11 and the main collecting pipe 12, is pressurized by the pressure pump 7, and is discharged through the isolation valve 32 and the liquid outlet pipe 13; fully mixing the produced water with a barium chloride aqueous solution in the process that the produced water of the oil well enters the filter tank 1; BaCl in aqueous barium chloride solution₂Reacting with NaHSO4 in the produced water of the oil well to generate sediment BaSO 4; after the precipitate is generated, one part of the precipitate sinks to the bottom of the filter tank 1 under the action of gravity, and the other part of the precipitate gradually moves upwards along with the mixed liquid, and the mixed liquid is attached to the surface of the filter tank after being filtered by the filter cylinder 3 in the upward movement process of the mixed liquid; HSO4 in the produced water of such a well^-The water is precipitated in a BaSO4 form under the action of a barium chloride aqueous solution, so that the aim of descaling the produced water of the sodium bisulfate type oil well is fulfilled;

2. ca of the produced water of a certain A well oil well can be measured according to the national standard SY/T5523-2016 oil-gas field water analysis method²⁺At a concentration of

、Cl^-At a concentration of

、Na⁺At a concentration of

、HSO4^-At a concentration of

，CaCl₂At a concentration of

Due to Ca²⁺Concentration ratio of (A) to (B) of (B)⁺Is higher than two orders of magnitude and Cl^-Concentration ratio of ions HSO4^-The concentration of the water is higher than two orders of magnitude, and the produced water of the oil well is of a calcium chloride type. The scale removal mode of the produced water of a well A is as follows:

(1) the inlet end of the medicine supply pump 6 is switched to be communicated with NaHCO₃The solution medicament supply system is communicated; NaHCO 2₃The concentration of the solution agent is C₃0.37 g/L; measured NaHCO in the produced water of an oil well₃Concentration C₄Is composed of

(ii) a The flow rate of the known feed pump 4 is 10⁵L/h，CaCl₂Has a relative molecular mass of 111, NaHCO₃Has a relative molecular mass of 84; the flow rate of the medicine supply pump 6 is set to be V₄L/h；；CaCl₂With NaHCO₃The reaction equation is as follows:

(3) After the gas in the filter tank 1 is discharged, the inlet end of the liquid supply pump 4 is communicated with the produced water of the oil well; opening the liquid outlet valve 11 and the isolation valve 32; then starting the liquid supply pump 4 and the medicine supply pump 6; the liquid supply pump 4 is set at 10⁵The L/h flow rate inputs the produced water of the oil well into the filter tank 1 through the liquid inlet pipe 9(ii) a Make the medicine supply pump 6 and

flux of NaHCO₃Pumping the solution into a filter tank 1; then the pressure pump 7 is started, after the pressure pump 7 is started, water and NaHCO are produced from the oil well in the filter tank 1₃After being filtered by the filter cartridge 3, the mixed liquid of the solution enters the pressure pump 7 after passing through the filter disc 2, the water outlet branch pipe 10, the liquid outlet valve 11 and the main collecting pipe 12, is pressurized by the pressure pump 7, and is discharged outside through the isolation valve 32 and the liquid outlet pipe 13; in the process that the produced water of the oil well enters the filter tank 1, the produced water of the oil well is mixed with NaHCO₃Mixing the solution thoroughly, NaHCO₃CaCl in solution and oil well produced water₂Reaction to form precipitated CaCO₃(ii) a In the process, the concentration of NaOH solution passing through the alkali supply pump 5 is 40g/L, and the NaOH solution is pumped into the filter tank 1 through the alkali supply pump 5, so that the NaOH solution is input into the filter tank 1 to achieve the purpose of adjusting the PH value in the filter tank 1; then, the PH value of the mixed liquor at the bottom of the tank in the filter tank 1 is kept at 8 by observing the reading of a PH test sensor and adjusting the flow of an alkali supply pump 5; besides, the descaling heater 14 is turned on simultaneously, so that the temperature of the mixed liquid in the filter tank 1 is kept at 70 ℃; after the precipitate is generated, one part of the precipitate sinks to the bottom of the filter tank 1 under the action of gravity, and the other part of the precipitate gradually moves upwards along with the mixed liquid, and the mixed liquid is attached to the surface of the filter tank after being filtered by the filter cylinder 3 in the upward movement process of the mixed liquid; ca in the produced water of such oil well²⁺Will be in NaHCO₃With the aid of CaCO₃The calcium chloride type oil well produced water is precipitated, so that the aim of descaling the calcium chloride type oil well produced water is fulfilled;

3. ca of the produced water of a certain C well oil well can be measured according to the national standard SY/T5523-2016 oil-gas field water analysis method²⁺At a concentration of

、Cl^-At a concentration of

、Na⁺At a concentration of

、HSO4^-At a concentration of

，NaHSO₄Concentration of

，CaCl₂At a concentration of

Ca detected from the produced water of the oil well²⁺Concentration and Na⁺Concentration difference is less than two orders of magnitude, and Cl^-Concentration sum HSO4^-If the concentration difference is less than two orders of magnitude, the produced water of the oil well is mixed; the scale removal mode of the produced water of the oil well of a certain C well is as follows:

two scale removal devices connected in series are used for respectively removing Na⁺、HSO4^-And Ca²⁺、Cl^-In the first descaling device, Na is removed first⁺、HSO4^-In a second descaling device to remove Ca again²⁺、Cl^-(ii) a The mixed oil well produced water descaling mode is as follows:

(1) in the first descaling device, the inlet end of a medicine supply pump 6 is switched to be communicated with a barium chloride aqueous solution medicine supply system; the concentration of the barium chloride aqueous solution is 208 g/L; in the second descaling device, the inlet end of the drug supply pump 6 is switched to NaHCO₃The solution medicament supply system is communicated; NaHCO 2₃The concentration of the solution medicament is 0.37 g/L;

the concentration of NaHSO4 in the produced water of the well was measured to be

(ii) a The flow rate of the liquid supply pump 4 in the first descaling device is 10⁵L/h, the flow rate of the medicine supply pump 6 is 6394L/h; setting NaHCO in the oil well produced water measured in the step 1₃At a concentration of

(ii) a Setting a second dividerThe flow rate of the liquid feed pump 4 in the scale apparatus is 10⁵L/h, the flow rate of the medicine supply pump 6 is

(ii) a Known as CaCl₂Has a relative molecular mass of 111, NaHCO₃Has a relative molecular mass of 84; BaCl₂Has a relative molecular mass of 208 and a relative molecular mass of NaHSO4 of 120; BaCl₂Reaction equation with NaHSO4 and CaCl₂With NaHCO₃The reaction equation is as follows:

(3) After the gas in the filter tanks 1 of the first descaling device and the second descaling device is discharged, the inlet end of a liquid feed pump 4 of the first descaling device is communicated with the produced water of the oil well; the inlet end of the liquid supply pump 4 of the second descaling device is communicated with the liquid outlet pipe 13 of the first descaling device; then simultaneously opening the liquid outlet valve 11 and the isolation valve 32 in the first descaling device and the second descaling device; then starting a liquid supply pump 4 and a chemical supply pump 6 in the first descaling device and the second descaling device; the liquid supply pump 4 in the first descaling device is arranged at 10⁵The produced water of the oil well is input into the filter tank 1 through the liquid inlet pipe 9 at the flow rate of L/h; pumping barium chloride aqueous solution into the filter tank 1 at the flow rate of 6394L/h by a drug supply pump 6 in the first descaling device; then the booster pump 7 in the first descaling device is started; after the pressurizing pump 7 is started, HSO4 in the first descaling device is completed^-The mixed liquid for descaling is conveyed into a second descaling device through a liquid outlet pipe 13; at this time, the liquid feed pump 4 in the second descaling device is set at 10⁵The flow of L/h is used for producing the oil well through the liquid inlet pipe 9Water is input into the second descaling device filter tank 1; NaHCO is supplied at a flow rate determined by the supply pump 6₃Pumping the solution into a filter tank 1; then a pressure pump 7 of the second descaling device is started, after the pressure pump 7 is started, mixed liquid in the filter tank 1 is filtered by the filter cylinder 3, then enters the pressure pump 7 after passing through the filter disc 2, the water outlet branch pipe 10, the liquid outlet valve 11 and the main collecting pipe 12, is pressurized by the pressure pump 7, and then is discharged through the isolation valve 32 and the liquid outlet pipe 13; in the process, the concentration of NaOH solution passing through the alkali supply pump 5 is 40g/L, and the NaOH solution is pumped into the filter tank 1 through the alkali supply pump 5, so that the NaOH solution is input into the filter tank 1 to achieve the purpose of adjusting the PH value in the filter tank 1; then, the PH value of the mixed liquor at the bottom of the tank in the filter tank 1 is kept at 8 by observing the reading of a PH test sensor and adjusting the flow of an alkali supply pump 5; besides, the descaling heater 14 is turned on simultaneously, so that the temperature of the mixed liquid in the filter tank 1 is kept at 70 ℃; ca in the thus-mixed solution²⁺Will be in NaHCO₃With the aid of CaCO₃The scale is precipitated, thereby achieving the purpose of descaling the mixed oil well produced water.

The descaling method for the oil well produced water has compact structure and smart design; the yield of the existing descaling device is improved by arranging the filter disc 2 and the filter cylinder 3 in the filter tank 1; the precipitate is inhibited from being redissolved by adjusting the pH value and controlling the temperature, so that the descaling effect is improved; therefore, the problems of poor descaling effect and low descaling efficiency of the existing descaling device are solved, and the requirement of enterprises on the descaling of the produced water of the oil well is met.

Claims

1. A descaling method for oil well produced water is characterized in that: the descaling method for the oil well produced water comprises the following steps:

1. na in the produced water of the oil well is measured according to the national standard SY/T5523-2016 oil-gas field water analysis method⁺、HSO4^-、Ca²⁺And Cl^-The concentration of (c); if the produced water of the oil well detects Na⁺Concentration ratio of (C) Ca²⁺Is two orders of magnitude higher, and HSO4^-Concentration ratio of ions Cl^-Of (2) to (b)If the produced water is two orders of magnitude higher, the produced water of the oil well is sodium bisulfate;

(1) switching the inlet end of a chemical supply pump (6) in the descaling device for the produced water of the oil well to be communicated with a barium chloride aqueous solution chemical supply system; the concentration of the aqueous barium chloride solution is C₂，C₂The concentration range of (A) is 208-312 g/L; setting the NaHSO in the oil well produced water measured in the step 1₄At a concentration of C₁(ii) a The flow rate of the liquid supply pump (4) is V1, and the flow rate of the medicine supply pump (6) is V₂(ii) a BaCl is known₂Has a relative molecular mass of 208 and a relative molecular mass of NaHSO4 of 120; BaCl₂The reaction equation with NaHSO4 is as follows:

(2) after the calculation of the processes is finished, communicating the inlet end of a liquid supply pump (4) in the oil well produced water descaling device with external clean water, then opening a liquid inlet valve (8) and an exhaust valve (20), then starting the liquid supply pump (4) to enable the liquid supply pump (4) to input the clean water into the filter tank (1), and closing the exhaust valve (20) when the filter tank (1) is filled with the clean water and clean water is discharged from an exhaust elbow (19); the exhaust function is to exhaust the air in the tank, detect whether the whole device is safe, and have the function of protecting the pump;

(3) the gas in the filter tank (1) is dischargedThen, the inlet end of the liquid supply pump (4) is communicated with the produced water of the oil well; opening a liquid outlet valve (11) and an isolation valve (32) of a descaling device for oil well produced water; then starting a liquid supply pump (4) and a medicine supply pump (6); the liquid supply pump (4) is set to V₂The produced water of the oil well is input into the filter tank (1) through the liquid inlet pipe (9); the medicine supply pump (6) is set at V₂Pumping the barium chloride aqueous solution into the filter tank (1) at the flow rate; then a pressure pump (7) is started, after the pressure pump (7) is started, mixed liquid of water produced by an oil well in a filter tank (1) and a barium chloride aqueous solution is filtered by a filter cylinder (3), enters the pressure pump (7) after passing through a filter disc (2), a water outlet branch pipe (10), a liquid outlet valve (11) and a main collecting pipe (12), is pressurized by the pressure pump (7), and is discharged outside the mixed liquid after being filtered through an isolation valve (32) and a liquid outlet pipe (13); fully mixing the produced water with a barium chloride aqueous solution in the process that the produced water of the oil well enters the filter tank (1); BaCl in aqueous barium chloride solution₂Reacting with NaHSO4 in the produced water of the oil well to generate sediment BaSO 4; after the sediment is generated, one part of the sediment sinks to the bottom of the filter tank (1) under the action of gravity, one part of the sediment gradually moves upwards along with the mixed liquid, and the mixed liquid is attached to the surface of the filter tank after being filtered by the filter cylinder (3) in the upward movement process of the mixed liquid; HSO4 in the produced water of such a well^-The water is precipitated in a BaSO4 form under the action of a barium chloride aqueous solution, so that the aim of descaling the produced water of the sodium bisulfate type oil well is fulfilled;

(1) the inlet end of a chemical supply pump (6) of a scale removal device for oil well produced water is switched to NaHCO₃The solution medicament supply system is communicated; NaHCO 2₃The concentration of the solution agent is C₃；C₃The concentration range of (A) is 0.3-0.6 g/L; setting NaHCO in the oil well produced water measured in the step 1₃At a concentration of C₄(ii) a The flow rate of the liquid supply pump (4) is V3, and the flow rate of the medicine supply pump (6) is V₄(ii) a Known as CaCl₂Has a relative molecular mass of 111, NaHCO₃Has a relative molecular mass of84；CaCl₂With NaHCO₃The reaction equation is as follows:

(2) after the calculation of the processes is finished, communicating the inlet end of a liquid supply pump (4) of the scale removal device for the produced water of the oil well with external clean water, then opening a liquid inlet valve (8) and an exhaust valve (20), then starting the liquid supply pump (4) to enable the liquid supply pump (4) to input the clean water into the filter tank (1), and closing the exhaust valve (20) when the filter tank (1) is filled with the clean water and the clean water is discharged from an exhaust elbow (19); the exhaust function is to exhaust the air in the tank, detect whether the whole device is safe, and have the function of protecting the pump;

(3) after the gas in the filter tank (1) is discharged, communicating the inlet end of the liquid supply pump (4) with the produced water of the oil well; opening the liquid outlet valve (11) and the isolation valve (32); then starting a liquid supply pump (4) and a medicine supply pump (6); the liquid supply pump (4) inputs the oil well produced water into the filter tank (1) through the liquid inlet pipe (9) at the flow rate of V3; the medicine supply pump (6) is set at V₄Flux of NaHCO₃Pumping the solution into a filtering tank (1); then the pressure pump (7) is started, after the pressure pump (7) is started, the oil well in the filter tank (1) produces water and NaHCO₃After being filtered by the filter cartridge (3), the mixed liquid of the solution enters the pressure pump (7) after passing through the filter disc (2), the water outlet branch pipe (10), the liquid outlet valve (11) and the main collecting pipe (12), is pressurized by the pressure pump (7), and is discharged outside by the isolating valve (32) and the liquid outlet pipe (13); in the process that the produced water of the oil well enters the filter tank (1), the produced water is mixed with NaHCO₃Mixing the solution thoroughly, NaHCO₃CaCl in solution and oil well produced water₂Reaction to form precipitated CaCO₃(ii) a In the process, the NaOH solution is pumped into the filter tank (1) by an alkali supply pump (5); NaOH solution concentration of C₅，C₅The concentration range of (A) is 4-40 g/L; the NaOH solution is input into the filter tank (1) to achieve the purpose of adjusting the PH value in the filter tank (1);then, the PH value of the mixed liquor at the bottom of the tank in the filtering tank (1) is kept at 8 by observing the reading of a PH test sensor and adjusting the flow of an alkali supply pump (5); additionally, the descaling heater (14) is required to be turned on simultaneously so that the temperature of the mixed liquid in the filter tank (1) is kept at 70 ℃; after the sediment is generated, one part of the sediment sinks to the bottom of the filter tank 1 under the action of gravity, one part of the sediment gradually moves upwards along with the mixed liquid, and the mixed liquid is attached to the surface of the filter tank after being filtered by the filter cylinder (3) in the process of moving upwards; ca in the produced water of such oil well²⁺Will be in NaHCO₃With the aid of CaCO₃The calcium chloride type oil well produced water is precipitated, so that the aim of descaling the calcium chloride type oil well produced water is fulfilled;

(1) in the first descaling device, the inlet end of a drug supply pump (6) is switched to be communicated with a barium chloride aqueous solution drug supply system; the concentration of the aqueous barium chloride solution is C₂，C₂The concentration range of (A) is 208-312 g/L; in the second descaling device, the inlet end of the drug supply pump 6 is switched to NaHCO₃The solution medicament supply system is communicated; NaHCO 2₃The concentration of the solution agent is C₃；C₃The concentration range of (A) is 0.3-0.6 g/L;

setting the concentration of NaHSO4 in the oil well produced water measured in the step 1 as C₁(ii) a The flow rate of the liquid supply pump (4) in the first descaling device is V1, and the flow rate of the chemical supply pump (6) is V₂(ii) a Setting NaHCO in the oil well produced water measured in the step 1₃At a concentration of C₄(ii) a The flow rate of the liquid supply pump (4) in the second descaling device is set as V3, and the flow rate of the chemical supply pump (6) is set as V₄(ii) a Known as CaCl₂Has a relative molecular mass of 111, NaHCO₃Has a relative molecular mass of 84; BaCl₂Relative molecular mass of 208, NaHSO4The mass is 120; BaCl₂Reaction equation with NaHSO4 and CaCl₂With NaHCO₃The reaction equation is as follows:

(2) after the calculation of the processes is finished, communicating the inlet end of the liquid supply pump (4) with external clean water, then opening the liquid inlet valve (8) and the exhaust valve (20), then starting the liquid supply pump (4) to enable the liquid supply pump (4) to input the clean water into the filter tank (1), and closing the exhaust valve (20) when the filter tank (1) is filled with the clean water and the clean water is discharged from the exhaust elbow (19); the exhaust function is to exhaust the air in the tank, detect whether the whole device is safe, and have the function of protecting the pump;

(3) after the gas in the filter tanks (1) of the first descaling device and the second descaling device is discharged, the inlet end of a liquid supply pump (4) of the first descaling device is communicated with the produced water of the oil well; the inlet end of a liquid supply pump (4) of the second descaling device is communicated with a liquid outlet pipe (13) of the first descaling device; then simultaneously opening a liquid outlet valve (11) and an isolation valve (32) in the first descaling device and the second descaling device; then starting a liquid supply pump (4) and a chemical supply pump (6) in the first descaling device and the second descaling device; the liquid supply pump (4) in the first descaling device is set to be V₂The produced water of the oil well is input into the filter tank (1) through the liquid inlet pipe (9); the chemical supply pump (6) in the first descaling device is set to V₂Pumping the barium chloride aqueous solution into the filter tank (1) at the flow rate; then a booster pump (7) in the first descaling device is started; after the pressurizing pump (7) is started, HSO4 in the first descaling device is completed^-The mixed liquid after descaling is conveyed into a second descaling device through a liquid outlet pipe (13); at the moment, a liquid supply pump (4) in the second descaling device inputs the oil well produced water into a second descaling device filter tank (1) through a liquid inlet pipe (9) at the flow rate of V3; the medicine supply pump (6) is set at V₄Flux of NaHCO₃Pumping the solution into a filtering tank (1); then the pressure pump (7) of the second descaling device is started, and the pressure pump (7) is startedAfter the filter tank is moved, mixed liquid in the filter tank (1) is filtered by the filter cylinder (3), then enters the pressure pump (7) after passing through the filter disc (2), the water outlet branch pipe (10), the liquid outlet valve (11) and the main collecting pipe (12), is pressurized by the pressure pump (7), and then is discharged outside the filtered mixed liquid through the isolation valve (32) and the liquid outlet pipe (13); in the process, the NaOH solution is pumped into the filter tank (1) by an alkali supply pump (5); NaOH solution concentration of C₅，C₅The concentration range of (A) is 4-40 g/L; the NaOH solution is input into the filter tank (1) to achieve the purpose of adjusting the PH value in the filter tank (1); then, the PH value of the mixed liquor at the bottom of the tank in the filtering tank (1) is kept at 8 by observing the reading of a PH test sensor and adjusting the flow of an alkali supply pump (5); additionally, the descaling heater (14) is required to be turned on simultaneously so that the temperature of the mixed liquid in the filter tank (1) is kept at 70 ℃; ca in the thus-mixed solution²⁺Will be in NaHCO₃With the aid of CaCO₃The scale is precipitated, thereby achieving the purpose of descaling the mixed oil well produced water.

2. A method of descaling oil well produced water according to claim 1, wherein: the descaling device for the oil well produced water comprises a filter tank (1), a filter disc (2), a filter cartridge (3), a liquid supply pump (4), an alkali supply pump (5), a chemical supply pump (6), a booster pump (7) and a main collecting pipe (12); the bottom of the filter tank (1) is connected with a liquid supply pump (4) through a liquid inlet valve (8) and a liquid inlet pipe (9); a plurality of filter discs (2) are arranged in the filter tank (1) at intervals in an up-down manner; a plurality of filter cartridges (3) are arranged on the lower end surface of the filter disc (2) at regular intervals; one side of the filter disc (2) is connected with a water outlet branch pipe (10); the water outlet branch pipe (10) extends to the outer end of the filter tank (1) and is communicated with the main collecting pipe (12) through a water outlet valve (11); the lower end of the main collecting pipe (12) is connected with a liquid outlet pipe (13) through a pressurizing pump (7); the bottom of the filter tank (1) is connected with an alkali supply pump (5) through a pipeline, and is connected with a drug supply pump (6) through a pipeline.

3. A method of descaling oil well produced water according to claim 2, wherein: the filter disc (2) is of a disc-shaped structure with a hollow inner part; the filter cartridge (3) consists of an inner framework (15), a filter fiber cartridge (16), an upper end cover (17) and a lower end cover (18); the circumferential surface of the inner framework (15) is provided with an upper end cover (17) and a lower end cover (18) which are connected by screw threads, and a filtering fiber cylinder (16) is arranged on the circumferential surface; the filter cartridge (3) is in threaded connection with the filter disc (2) through an upper end cover (17).

4. A method of descaling oil well produced water according to claim 3, wherein: the bottom of the filter tank (1) is provided with a descaling heater (14); the lower part of the filter tank (1) is provided with a temperature sensor and a PH test sensor.

5. An oil well produced water descaling method according to claim 4, wherein: the bottom of the filter tank (1) is connected with a sewage pump (22) through a pipeline; an outlet of the sewage pump (22) is sequentially connected with an overflow layering box (23) and a lifting pump (24); the outlet end of the lift pump (24) is communicated with the liquid outlet pipe (13) through a pipeline and a valve.

6. An oil well produced water descaling method according to claim 5, wherein: the overflow layering box (23) is composed of a layering box body (25), a partition plate (26) and a water turning plate (27); a plurality of partition plates (26) are fixedly arranged in the layered box body (25) at intervals; the layered box body (25) is divided into a plurality of chambers by the partition plates (26); a distance is reserved between the upper end of the isolation plate (26) and the edge of the layered box body (25); a water turning plate (27) is arranged in the layered box body (25) at one side of the isolation plate (26); the lower end of the water turning plate (27) is at a certain distance from the bottom plate of the layered box body (25); the upper end surface of the water turning plate (27) is higher than the upper end of the isolation plate (26); the upper end of the right side of the layered box body (25) is communicated with a sewage pump (22); the upper end of the left side of the layering box body (25) is communicated with a lifting pump (24); the partition plate (26) in the layered box body (25) is gradually raised from left to right.

7. An oil well produced water descaling method according to claim 6, wherein: a purging main pipe (30) is arranged in the filtering tank (1); a purging branch pipe (28) is arranged above the filter disc (2); a plurality of purging nozzles (29) are arranged on the purging branch pipe (28); the purging branch pipe (28) is communicated with the purging main pipe (30); the upper end of the purging main pipe (30) extends to the outer end of the filter tank (1) and is communicated with the liquid outlet pipe (13) through a flushing pipe (31) and a valve; the liquid outlet pipes (13) at the two sides of the flushing pipe (31) are respectively provided with an isolation valve (32).

8. A method of descaling oil well produced water according to claim 7, wherein: the liquid outlet pipe (13) at the outlet of the pressure pump (7) is communicated with the bottom of the filter tank (1) through a safety detection pipe (33) and a valve; a differential pressure sensor (34) is arranged on the water outlet branch pipe (10); one probe of the differential pressure sensor (34) is communicated with the corresponding water outlet branch pipe (10), and the other probe is communicated with the filter tank (1).

9. A method of descaling oil well produced water according to claim 8, wherein: the upper end of the filter tank (1) is provided with an exhaust elbow (19) through an exhaust valve (20).

10. A method of descaling oil well produced water according to claim 9, wherein: one side of the filter tank (1) is provided with a gas storage tank (21); the air storage tank (21) is communicated with the main collecting pipe (12) through a pipeline and a blowback valve (22).